PART !: NEUTRON SPECTRUM PARAMETER iEASURE^ENTS · Relative gold-copper, lutetium-copper, or indium-manganese, lutetium-manganese activity ratios were determined in the perturbed

1-2

PART !: NEUTRON SPECTRUM PARAMETER iEASURE^ENTS

by

P.M. French

Chalk River Nuclear Laboratories

Chalk River, Ontario

November 1972

AECL-4260

URANIUM BOOSTER ROD EXPERIMENTS IN ZED-2

PART I: NEUTRON SPECTRUM PARAMETER MEASUREMENTS

bv

P.M. French

Chalk River Nuclear Laboratories


November, 1972

AECL-4260

URANIUM BOOSTER ROD EXPERIMENTS IN ZED-2

PART I ; NEUTRON SPECTRUM PARAMETER MEASUREMENTS

by

P .M. F r e n c h

A B S T R A C T

Neutron spectrum parameter measurements were performed inthe ZED-2 critical facility with four types of 235U boosters.One type was nominally 20% enriched diJi:>U, 4.74 g " DU/cmlength; the other three were 93% enriched with 235U loadingsof 2.21 g/cm, 3.49 g/cm, and 4.88 g/cm. The boosters werelocated interstitially, parallel tc reference fuel assembliesIn some experiments, three boosters were inserted in threesymmetric configurations that varied the flux couplingbetween boosters. Measurements were also made with oneor three booster assemblies perpendicular to the referencefuel assemblies.

Relative gold-copper, lutetium-copper, or indium-manganese,lutetium-manganese activity ratios were determined in theperturbed regions of the core and interpreted in terms ofthe Westcott spectral parameters r and T n or r/Tn/To.

The results indicate that spectral perturbations are largenear the boosters, but do not extend much more than two orthree slowing down lengths from the booster sites.

Manuscript prepared June 1972

Chalk River Nuclear LaboratoriesChalk River, Ontario

November 1972

AECL-4260

Expériences effectuées, dans le ZED-2tavec des barres de surréactivité en uranium

Première Partie: Mesure des paramètres de spectres de neutrons

par

P.M. Trench

Résumé

Des mesures de paramètres de spectres de neutronsont été effectuées dans l'ensemble critique ZED-2 avec quatretypes de barres de surréactivité en 235u. L'un de ces typesétait constitué par 235u enrichi a 20%: 4.74 g 235U/cm; lestrois autres étaient enrichis à 93% avec des charges de 235JJde 2.21 g/cm, 3.49 g/cm, et 4.88 g/cm. Les barres desurréactivité étaient placées parallèlement aux ensemblescombustibles de référence. Dans quelques expériences, troisbarres de surréactivité ont été insérées dans trois configura-tions symétriques qui faisaient varier le couplage du fluxentre les barres de surréactivité. Des mesures ont étéégalement faites avec une ou trois barres de surréactivitéplacées perpendiculairement aux ensembles de combustible deréférence.

On a déterminé les rapports relatifs d'activitéor-cuivre, lutëtium-cuivre ou indium-manganèse, lutétium-manganèse dans les régions perturbées du coeur et on les ainterprétés en fonction des paramètres spectraux de Westcottr et T ou r / T /T .n n o

Les résultats montrent que las perturbations spectralessont importantes près des barres de surréactivité mais nes'étendent pas a plus de deux ou trois longueurs de ralentissementdes emplacements des barres de surréactivité.

L'Energie Atomique du Canada, LimitéeLaboratoires Nucléaires de Chalk River


Novembre 1972 AECL-4260

- 1 -

INDEX

Page

LIST OF FIGURES i t i

LIST OF TABLES v

1. INTRODUCTION 1

2. FUEL AND REFERENCE LATTICE CONFIGURATIONS 3

2.1 Reference Lattices 3

2.2 Booster Rods and Suspension Systems 5

3. EXPERIMENTS 16

3.1 General Discussion of Method 16

3.2 Activation Measurements 183.2.1 Spectral Parameter Measurements 183.2.2 Determination of Activities 21

3.3 Experimental Configurations 223.3.1 61-element Booster Measurements 223.3.2 Measurements with Interacting

Boosters 253.3.3 Reference Lattice Measurements 27

4. RESULTS AND DISCUSSION 29

4.1 61-element Booster Results 294.1.1 Boosters Parallel to Reference

Fuel Assemblies 294.1.2 Booster Perpendicular to Reference

Fuel Assemblies 414.2 Interacting Booster Results 45

4.2.1 Boosters Paral lel to ReferenceFuel Assemblies 45

4.2.2 Boosters Perpendicular to ReferenceFuel Assemblies 47

4.3 Detector Normalization Experiment 51

-11- 1

IPage

SUMMARY AND CONCLUSIONS 53 '

ACKNOWLEDGMENTS 55

REFERENCES 56

APPENDIX A 57

Properties of Neutron Detector Foils

APPENDIX B 58

Macroscopic Neutron Spectrum Results :61-element Boosters Parallel to ReferenceFuel Assemblies

APPENDIX C 63

Spectral Perturbation Factor Results :61-element Boosters Parallel to ReferenceFuel Assemblies

APPENDIX D 65

Neutron Spectrum Results : 33-element and17-element Interacting Boosters Parallelto Reference Fuel Assemblies

APPENDIX E 73

Comparison of Neutron Spectrum DetectionMethods.

-iii-

LIST OF FIGURES

Page

1. 28-element Natural UO2 Cluster 3

2. 52 Rod square Reference Lattices andCo-ordinate Labelling 4

3. 55 Rod Hexagonal Reference Lattice andCo-ordinate Labelling 4

4. 61-element High Enrichment Booster Cluster 6

5. High Enrichment Booster Fuel Elements 7

6. High Enrichment Booster Suspension System 9

7. 61-element LOW Enrichment Booster Cluster 10

8. Low Enrichment Booster Fuel Element 11

9. 61-element Low Enrichment Booster - HorizontalSuspension in ZED-2 13



12. Typical Lattice Arrangement with Detectors - 1928.58 cm square (D2O) Lattice and 61-elementLow Enrichment Booster

13. Spectrum Detectors on Aluminum Framework in 20Moderator

14. Lattice Configurations with Three Interacting 26Boosters Parallel to Reference Fuel Assemblies

15. 3, 17-element Boosters - Horizontal Configuration28in ZED-2

16. r/T /T SE of Lattice Center : Case 28-10 30n o

-iv-

Page

17. r/T /T SE of Lattice Center : Case 28-20 30

n o18. r/T /T SE of Lattice Center : Case 28-30 31

n o19. r/T M SE of Lattice Center : Case 27-10 34

n o20. r/T /T SE of Lattice Center : Case 27-20 34

n o21. Spectral Perturbation Factors SE of Lattice 39

Center : Case 28-20

22. Spectral Perturbation Factors SE of Lattice 39Center : Case 28-30

23. Spectral Perturbation Factors SE of Lattice 40Center : Case 27-20

24. Axial r/Tn/TQ : Case 28-40 44

25. Axial r/T /T : Case 28-57 47n o

LIST OF TABLES

1. Spectrum Measurement Experiments 23

2. Measured Neutron Spectrum Parameters in a 31Lattice Cell - Case 28-10 : 28.58 cm (D2O)Reference Lattice

3• Measured Neutron Spectrum Parameters in a 3 2

Perturbed Lattice Cell - Case 28-20:28.58 cm (D2O) Reference Lattice; 61-element20% 235u BoSster at K0

4. Measured Neutron Spectrum Parameters in 33a Lattice Cell - Case 28-30 : 28.58 cm (D2O)Reference Lattice; 61-element 93% 2 3 5UBooster at KO

5. Measured Neutron Spectrum Parameters in a 35Lattice Cell - Case 27-10 : 27.94 cm (Air)Reference Lattice

6. Measured Neutron Spectrum Parameters in a 36Perturbed Lattice Cell - Case 27-20: 27.94cm (Air) Reference Lattice; 61-element 20%235u Booster at K0

7. Measured Neutron Spectrum Parameters - 37Comparison of Square Lattice VerticalBooster Results

8. Measured Neutron Spectrum Parameters in 42Lattice - Case 28-40 : 28.58 cm (D20)Reference Lattice; 61-element 20% 2 3 5UBooster Perpendicular Along K at 80 cmElevation

9. Measured Neutron Spectrum Parameters at 43Booster Rod - Case 28-40 : 28.58 cm (D2O)Reference Lattice; 61-element 20% 235uBooster Perpendicular Along K at 80 cmElevation

-VI-

10. Axial Spectral Perturbations, S(r,z) - 44Case 28-40 : 28.58 cm (D2O) ReferenceLattice; 61-element 20% 2 3 5U BoosterPerpendicular Along K at 80 cm Elevation

11. Measured Neutron Spectrum Parameters - 46Comparison of Hexagonal Lattice Results

12. Measured Neutron Spectrum Parameters in 48Lattice - Case 28-57 : 28.58 cm (D2O)Reference Lattice? 3, 17-element Inter-action Boosters Perpendicular

13. Measured Neutron Spectrum Parameters at 49Booster Rod - Case 28-57 : 28.58 cm (D2O)Reference Lattice; 3, 17-element Inter-action Boosters Perpendicular

14. Axial Spectral Perturbations, S (r,z) - 49Case 28-57 : 28.58 cm (D2O) ReferenceLattice,- 3, 17-element Interaction BoostersPerpendicular

APPENDIX A

A-l Detector Parameters 57

APPENDIX B

B-l Macroscopic Measured Neutron Spectrum 58to Parameters - Square Lattice VerticalB-5 Booster Results

APPE17DIX C

C-l Detailed Spectral Perturbation Factors, 63to S(r), SE of Lattice Center - 61-elementC-3 Booster Results

-vii-

APPENDIX D

D-ltoD-8

Measured Neutron Spectrum ParametersHexagonal Lattice Results

65

APPENDIX E

E-l

E-2

Comparison of various Spectral Para- 73meter Measurement Methods

r/T /T Values - In/Mn Converted to 74Au/8u.8ase 28-10 : 28.58 cm (D20)Reference Lattice

- 1 -

1. INTRODUCTION

In an operating power reactor, the production of

the neutron poison i 3 5Xe, and its removal through decay

and absorption, are balanced at some equilibrium level

determined by the neutron flux. When the reactor is

shut down, however, the removal of 135Xe through neutron

absorption ceases immediately while production from

decay of the precursor fission product chain 135Te and1351 decreases more slowly with the half-lives of these

isotopes. Therefore, the 135xe concentration increases

rapidly to a maximum in about 10 hours, then decays slowly

to the equilibrium level about 30 or 40 hours after shut-

down. Similar effects occur with reductions to lower

reactor power.

As the fraction of nuclear to total power generated

by a utility increases, if. becomes more important that a

substantial number of power stations have good load fol-

lowing characteristics. Localized, enriched 239pu or 235u

"booster" fuel assemblies are one method currently proposed,

or in use in CANDU type power reactors, to provide suf-

ficient excess reactivity for start-up following a short

shutdown, or for some measure of load following capability.

Boosters, however, are heavy thermal neutron absorbers and

strong fast neutron sources, and introduce large flux

perturbations in the core. Also, it is now clear that

irradiated fuel element sheaths, of current design, will

not tolerate significant increases in local power over

normal levels, even if maximum allowed fuel rating is not

exceeded. If enriched, localized driver fuel assemblies,

or boosters, are to be used in future reactors, therefore,

it is important that reactor design calculations predict

- 2 -

flux perturbations with a high degree of accuracy.

A number of experimental booster studies have been

conducted at Chalk River to provide a standard set of

results for comparison with calculation. Recently, Roshd '

investigated single boosters of three different 2 3 5U

loading. The results indicated that neither reactivity

or flux perturbation effects were proportional to 2 3 5U

loading due to booster self shielding effects.

This report is the first of a series describing

experiments performed in ZED-2 to investigate other uranium

booster effects. Recent interest in relatively low enrich-

ment boosters has prompted a series of detailed reactivity and

flux perturbation experiments to compare a 20% 2 3 5U enriched

61-element booster assembly with a similar 93% enriched

assembly investigated by Roshd. In addition, multiple booster

interaction effects have been studied, with up to three

boosters in the cores; two sets of boosters were used, with

different 23SU loadings.

The experiments described here investigate neutron

spectrum effects in the boosted cores. The results are

interpreted in terms of the Westcott epithermal index, r,

a measure of the opithermal neutron fraction, and the

effective temperature, T , of the thermal neutron Fixwellian

distribution. Future reports will deal with measurements

of reactivity and flux perturbations, and conversion ratio

measurements with the lower enrichment booster.

- 3 -

2.

2.1

FUEL AND REFERENCE LATTICE CONFIGURATIONS

Reference Lattices

All reference lattices consisted of 28-element

natural U0 2 fuel assemblies shown in Figure 1 and were

either air or D2O cooled. Three lattice configurations

were used.

(1) 28.58 cm (11.25") square pitch, D20

cooled, 52 rod, open centre.

(2) 27.94 cm (11.00") square pitch, air-

cooled, 52 rod, open centre.

(3) 30.00 cm hexagonal pitch, D2O cooled

55 rod, closed centre.

U02 FUEL

DIAMETER 1.42 cmDENSITY 10.45 g/cc

Zr-2 SHEATH

I.D. 1.43cmO.D. 1.52cm

AL PRESSURE TUBE

I.D. 10.19 cmO.D. 10.78 cm

AL CALANDRIATUBE

I.D. 12.46cm.O.D. 12.74 cm

AIR ANNULUS

DEMOUNTABLE ELEMENTS NUMBERED I TO 6

Fig. 1 28-element natural UO2 cluster

W

o o o oo o o o o o

o o o o o o o oo o o o o o o oo o o o o o o oo o o o o o o oo o o o o oo o o o

o

N

M

L

K

J

H

6

1. 28 58 CM, D 2 0 COOLED

2. 2794 CM, AIR COOLED

CALANDRIA RADIUS = 168 CMGRAPHITE REFLECTOR

OUTER RADIUS ~ 228 CM

Fig. 2 52 rod square reference lattices

and co-ordinate labelling

B 6 4 2 O 2 4 6 8

I 1 1 1 1 1 1 1 1-W E

o o oo o o o o o

o o o o o o o

o o o o o o o oo o o o o o o


o o o o o o

o o o

N

M

L

- - K

- - J

H

6

30 CM PITCHD 2 0 COOLANT

CALANDRIA RADIUS » 168 CMGRAPHITE REFLECTOR

OUTER RADIUS ~ 228 CM

Fig. 3 55 rod hexagonal reference lattice

and co-ordinate labelling

- 5 -

The 30.00 cm hexagonal lattice fuel-to-moderator volume

ratio approximated that of the 28.58 cm square lattice.

Figures 2 and 3 show the reference lattice configurations

and their respective co-ordinate labelling.

The 28-element fuel assemblies are described in detail

in References 2 and 3. Each rod was composed of 5, 28-

element bundles (49.67 cm in length) stacked inside a

housing assembly consisting of an Al pressure tube sur-

rounded by an Al calandria tube. One bundle was available

for activation measurements inside the fuel. The end plates

of this handle were in two sections that could be easily

split, thus facilitating rapid removal of the six elements

that contained the detector foils (see Fig. 1).

The moderator purity and temperature varied during

the experimental program, and are recorded in the tables

of results.

2.2 Booster Rods and Suspension Systems

The 93.16% 235U enriched (high enrichment) booster

was composed of 61 fuel pencils arranged in five rings

as shown in Figure 4, Each pencil measured 216.2 cm

long (208.87 cm effective fuel length) and contained

a core of U-Al alloy (22.5 wt% U*a , 0.386 cm in diameter

bonded to an Al sheath (see Fig. 5). The booster

loading was 4.88g 235U/cm length. The clusters were

assembled with two drilled end plates and four spacer

plates so that individual elements could be withdrawn

axially.

(a) The U-Al alloy content ratio was nominally 22.5 wt%but activation measurements interpreted by A. Okazakiyielded 23.1 + .2 wt%.

(4)

- 6 -

SUPPORT TUBEO.D. 11.43 cmI.D. 11.10 cm

"LOW CONCENTRATION"ELEMENT

(22.5 w t% U - A L C O R E )4.427 «


Fig. 4 61-element high enrichment booster cluster

Eight elements were demountable and each was con-

structed so that activation detectors could be placed in

a gap inside the fuel, or around the sheath, as shown in

Figure 5.

The cluster was suspended in the reactor in an 11.43

cm O.D, support tube (0.165 cm wall), 231.1 cm long. The

U-AI CORE ALUMINIUM SHEATH

/ / / / / / / . / . . / _ / • •

'/r/L" "\

- 8 -

top flange of this tube was bolted to the top of a second

Al tube 166 cm long and the lower end was extended with a

tube section 10.63 cm long. This booster assembly was sus-

pended from an Al suspension bar bolted to the top of two

Al clamps, which were in turn firmly attached to the two

central lattice beams (see Figure 6). The bottom of the

assembly was 0.3 cm from the floor of the reactor vessel

to avoid any reactivity increase should the booster fall to

the floor. A safety bracket was welded to the top of the

booster assembly and was fitted around the two support clamps.

This arrangement ensured that the booster would not tip

over into the reactor if the suspension system were to

fail, but allowed the assembly to hang "plumb" in the core*

Slots in the support tube allowed the booster to be

"cooled" by reactor D2O moderator.

Further details of this booster are given in Reference

1.

The low enrichment booster consisted of 61 fuel pencils

arranged in five rings as shown in Figure 7. Each pencil

measured 188.28 cm in length (179.83 cm of fuel) and con-

sisted of a core of U-Al alloy (24.5 wt% lTa , density =

3.38 + 0.05 g/cm3) 0.775 cm in diameter sheathed in Zircalloy*5*

(0.963 cm O.D.; 0.076 cm wall) as shown in Figure 8. The

uranium was 19.91% 2 3 5u enriched and the 61-element 2 3 5U

loading was 4.74 g/cm length. The pencils were assembled

in a cluster with two drilled end plates and three spacer

plates.

(a) The U-Al alloy concentration was nominally 24.7 wt%but activation measurements yielded 24.5 +_ 0.05 wt%.

- 9 -

SUSPENSION BAR

SAFETY BRACKET

ALUMINUM CLAMP

ZED-2 SUPPORT BEAM

61 ELEMENT BOOSTERASSEMBLY

EXTENSION RING

CALANDRIA FLOOR

Fig. 6 High enrichment booster suspension system

- 10 -

SUPPORT TUBE

OD: 11.43 CMID! 11.10 CM

= 0.0

\

CMR2 = I •270 CM

oooo


Fig. 7 61-element low enrichment booster cluster

Eight elements were demountable and could be withdrawn

axially. These elements consisted of U-Al alloy pellets

15.24 cm and 3.50 cm in length stacked inside the Zircaloy

ZR-2 END FITTING

(WELDED)U-AL PELLET COREOD: 0.775 cm

t0.963 0

1

D635|

-O953- 2.220 cm 179.83 cm

188.28 cm

ZR-2 SHEATH0 0 : 0.963 cmID! 0.811 cm

-2.540cm-

0,470

' 0.953 O.63§1.905 cm

NORMAL BOOSTER FUEL ELEMENT

REMOVABLEZR-2 END FITTING

SEAL

DETECTORS LOCATED INGAPS BETWEEN PELLETS

U-AL PELLETCORE

SLOTD>DYIOUNTABLE BOOSTER FUEL ELEMENT

Fig. 8 Low enrichment booster fuel elements

- 12 -

sheaths described above. The end fittings were removable

for access to the fuel. As shown in Figure 8, each demount-

able element had grooves machined in the sheath (0.520 cm

wide; 0.043 cm deep) to accommodate strip activation detectors,

49.45 cm from the base of each element (60.00 cm from the

floor of the ZED-2 reactor, when the booster was suspended

in the core).

The booster cluster was suspended in the reactor in

an 11.43 cm O.D. Al support tube (0.165 cm wall), 231.1

cm long. The vertical suspension system was similar to

that of the high enrichment booster. The horizontal

suspension consisted on two Al clamps around the support

tube, connected to 1.27 cm O.D., 0.089 cm wall Al tubes

with Al universal joints, as shown in Figure 9. The

suspension systems were secured to the beams supporting the

fuel assemblies.

The 33-element boosters are shown in Figure 10. The

pencils were identical, geometrically, to the high enrich-

ment pencils, but two U-Al alloys were used: a high con-

centration of nominal 37.7 wt% U and a low concentration

of nominal 22.5 wt% U. The pencils were arranged in four

rings to form the clusters; the inner and third rings were

high concentration elements. The booster loading was 3.49g235U/cm length. The clusters were housed in 8.89 cm O.D.

(0.165 cm wall) Al support tubes and suspended in a similar

manner to the 61-element boosters.

Six elements were demountable so that activation measure-

ments could be made in the fuel pencils. They were the same

as the BLW (boiling light water) demountable elements

of Figure 5.

- 13 -

167.6 cm

II

u

AL SUPPORT TUBEOD ". I ! . 4 3 cmI D : 11.10 cm

CENTER OF FUELAT LATTICE CENTER

\

\

\AL CLAMP BOOSTER CLUSTER

SUSPENSION BARCLAMPED TOBEAM

REACTORSUSPENSIONBEAM

AL GIMBAL aCHAIN SUSPENSION

AL TUBE

186.0 cm

AL UNIVERSALJOINT

. AL END PLATE

8 0 0 cm FROMFUOOR OFREACTOR VESSEL

Fig. 9 61-element low enrichment booster -horizontal suspension in ZED-2

= 0.0 CM

SUPPORT TUBE

OO: 8.89 CMI D: 8. 56 CM

HIGH CONC. (37.7 wt „ U-AI)

LOW CONC. (22.5 \ % U-AI)

DEMOUNTABLE ELEMENT NUMBERED I TO 6

Fig. 10 33-element high enrichment

booster cluster

SUPPORT TUBE

OD. 8.89 CMID. 8.56 CM

HIGH CONC. (37.7 wt. % U-AL)

LO W CONC. (22.5 w t. % U -AL)


Fig. 11 17-element high enrichment

booster cluster

- 15 -

The 17-element boosters wers obtained by removing the

outer ring of 16 low concentration elements from the 33-

element boosters as shown in Figure 11; the resulting 235u

loading was 2.21 g/cm length. Four elements were demount-

able. The suspension systems and support tubes were identical

to the 33-element boosters and the horizontal suspensions

were similar to that for the low enrichment 61-element booster.

- 16 -

3. EXPERIMENTS

3.1 General Discussion of Method

Spectral effects were interpreted using the Westcott

formalism . The parameter r, a measure of the epithermal

neutron density, and Tn, the effective neutron temperature

of a Maxwellian distribution of neutrons, were determined

using the method described in detail by Bigham et al.

Thin foils of Au-Al, Lu-Al and Cu were irradiated together

in "packages" in the booster cells, at various locations

in the core, and at a thermal reference location (thermal

pit) in the D20 moderator, outside the reactor core. At the

reference site, the neutron spectrum was essentially a

Maxwellian distribution with the temperature assumed equal

to the physical moderator temperature.

The relative foil activity ratios are related to the

neutron spectral parameters by the following expressions:

RAu = {AAu/ACu]x a n d RLu =

(ALu

c u th C u th

where x refers to the measurement position in the lattice

cell, th to the thermal reference locations, and where A,

the foil activity is given in Westcott notation by:

and Gr are the thermal and resonance foil self shielding

tors respectively. 9(Tn) denotes the tem

dence of the Westcott g value for Au and Lu.

factors respectively. 9(Tn) denotes the temperature depen-

- 17 -

At the reference location, r/T /T was determinedn o

from a Cd ratio measurement with thin In-Al foils,

g values were taken from Westcott.*6' Values of the

self shielding factors were determined by S.L. Mehta

(Appendix A ) : Gt was calculated using Hanna's method

and GrSQ was determined from the Cd ratio measurement

method described by Walker et al. , using thin

deposited Au foils as standards. The spectral parameters

were obtained from the data using existing Chalk River

codes, modified for Au instead of In, by S.L. Mehta.

The high radiation fields near the booster assemblies

several hours after irradiation necessitated the use of

Au and Cu detectors; the half-lives of In and Mn, the

standard spectral detectors, were considered too short for

accurate statistics during the counting of the activated

detectors, due to the long waiting period before counting.

Unfortunately, this meant that Westcott spectral parameters

determined with Au detectors in the vicinity of 2 3 8U rich

fuels would be significantly lower than those measured

with In. The Au activation at its major resonance (4.91 eV)

would not be representative of the spectra due to the

presence of the large 2 3 8u resonance at 6.68 eV. Never-

theless, it was felt that the Au/Cu activation ratios

could be usefully compared with cell codes such as HAMMER

where the spectrum is represented by a sufficiently large

number of energy groups.

In addition to using Au-Al, Lu-Al and Cu detectors, Au

and Cu strips were used for booster fuel pin sheath measure-

ments, and spectral detector method normalization measurements

were made with Lu-Mn-Al and In-Al alloy material.

- 18 -

3.2 Activation Measurements

3.2.1 Spectral Parameter Measurements

Activation measurements were made using packages of

nominal 1% Au-Al alloy (0.025 cm thick), nominal 10%

Lu-Al alloy (0.013 cm thick), and 0.013 cm thick Cu foils.

Both 1.43 cm and 0.775 cm diameter detectors were employed.

Other normalization measurements were made with 1.43 cm

diameter packages of nominal 1% In-Al alloy (0.013 cm thick)

and 0.025 cm thick nominal 10% Lu - 5% Mn-Al alloy foils.

All foil packages were wrapped in 0.003 cm thick Al and

irradiated between fuel pellets in the 28-element UO2

reference assembly split bundle elements, between fuel

pellets in the 61-element low enrichment booster elements,

on booster pressure tube and reference assembly calandria

tube surfaces, and at moderator sites, and at the reference

location in Al thimbles. 0.5 cm wide, 0.001 cm thick Au

and 0.013 cm thick Cu strips were wrapped together around

the demountable booster elements in the slots machined in

the sheaths, to measure the r/T /T spectral indices at

the sheath surfaces. Difficulty in accurately positioning

foils within the high enriched booster elements precluded

measurements of spectral parameters or fluxes in these

fuel element cores.

Figure 12 shows representative foil locations in a

typical ZED-2 lattice. In some experiments measurements

were also made at various moderator sites near the centre

of the core (Looster site); detector packages were secured

to a light Al framework extending from the booster and from -

a nearest neighbor reference fuel assembly (Figure 13).

- 19 -

O 28 -ELEMENT FUEL ROD

© 61 - ELEMENT BOOSTER

- FOILS IN THIMBLES

0 FOILS ON CALANDRIA TUBE

Q * t FOILS ON AL FRAMEWORK

X FOILS AT THERMAL REFERENCE

6W 4W 2W 0 2E 4|E 6E

o o o oo o o o o o

o o o o o o o oo - o o 0 * 0 0 0 0o o o 6 o oo o o o o o o o

o o o o o o_o o o o

NORTH

12 Typical lattice arrangement with detectors -28.58 cm square (D-O) lattice and 61-element lowenrichment booster

.LATTICE CENTERKO

AL FRAMEWORK

DETECTORPACKAGE

CELL CORNERJ2E

JKIEREFERENCE

ASSEMBLY

CELL CORNERJ 2 E

UNPERTURBED REFERENCE LATTICE PERTURBED BOOSTER LATTICE

Fig. 13 Spectrum detectors on Aluminum framework in moderator

- 21 -

In each experiment with boosters parallel to reference

fuel assemblies, all detectors were at approximately

the same elevation in the core, near the axial flux

maximum.

At the thermal reference location (Figure 12), r/T /Tno

was measured with pairs of 1.13 cm diameter, 0.013 cm

thick nominal 1% In-Al alloy foils, each foil in a box of

Cd or Al (0.076 cm thick walls). The Cd boxes were

positioned at least 20 cm above or below other detector

materials, to avoid flux perturbation effects. Corrections

for different axial flux values at the Cd and Al box

locations were made using a set of Cu foil axial flux

detectors in a nearby thimble.

3.2.2 Determination of Activities

The y-xay activities of the irradiated foils were

determined using a pair of 5.08 cm diameter (2.54 cm thick)

Nal (Tl) scintillation detector systems in ~ 4ir geometry.

An automatically restacking sample changer inserted "lucite"

sample trays, each containing an active foil, in sequence

in a small gap (< 2 cm) between the faces of two scintil-

lators. :

The output from each detector was digitalized on paper

tape and computer analyzed to correct each foil for decay,

counter dead-time losses, background, and isotopic content.

Since the alloyed foils used were not uniform, the relative

isotopic content of each detector was determined from

relative activities after irradiation on a rotating wheel

in the NRU thermal column.

- 22 -

The 12.75 h 61*Cu activity, 6.71 day 177Lu isomeric

activity, 2.70 day 198Au activity and the 54 minute 116In

isomeric activity were determined by counting with an

effective bias level of ~ 50 keV. The 2.58 h 56Mn activity

was determined at a bias level of - 500 keV to exclude all

Lu activities in the Lu-Mn-Al composite foils.

The In foils were counted begining ~ one hour after

irradiation. The Mn component of the Lu-Mn-Al composite

foils was counted ~ three hours after irradiation; the

Lu component was counted two or three days after the

irradiation to ensure that both the short lived Lu isomer

activities and the Mn activity had fully decayed. The Cu

and Au foils were counted one or two days following the

irradiation. Reactor power, irradiation time, and length

of time waited before specific foil counting were optimized

to reduce counter deadtime losses associated with high

count rate, but without sacrificing statistical accuracy.

In each case, sufficient counts were accumulated to ensure

a fractional standard error of less than 0.5%.

3 . 3 Experimental Configurations

list of all experimental reactor configurations is

outlined in Table 1 and case numbers are assigned for

reference in the tables of results. Critical moderator

levels, and moderator temperature and D2O purity are also

listed.

3,3.1 61-Element Booster Measurements

The D2O cooled 61-element boosters were located inter-

stitially, parallel to the reference fuel, at the center

TABLE 1

SPECTRUM MEASUREMENT EXPERIMENTS (a)

CaseNo.

27-10

27-20

28-10

28-20

28-30

28-40

28-57

30-10

30-24

30-32

30-42

30-44

30-50E

30-52D

30-65

Detec-torNorm.

EXPERIMENTAL CONFIGURATION (b)

27.94 cm square (AIR) reference lattice

61-element 20% Z 3 5U booster at K0 (in lattice 27-10)

28.58 cm square (D2O) reference lattice

61-element 20% 2 3 SU booster at K0 (in lattice 28-10)

61-element 93% 2 3 5U booster at K0 (in lattice 28-10)

61-element 20% 2 3 5U booster horizontal at 80.0 cm along K

3, 17-element 93% 2 3 5U boosters horizontal: 2 at 30.5 cmalong J and L and 1 at 80.0 cm along K

30.00 cm Hex (D2O) reference lattice

3, 33-element 93% 2 3 5U boosters at KL0, JK1E, JK1W (TIGHT)

3, 33-element 93% 2 3 5U boosters at LM0, JK2E, JK2W (MED)

3, 33-element 93% 2 3 5U boosters at MHO, IJ3E, U 3 W (LOOSE 1)

3, 33-element 93% 2 3 5U boosters at MN0, IJ4E, IJ4W (LOOSE 2)

Lattice 30-10 with central 19 rods voided

Lattice 30-50E with 3, 33-element 93% 2 3 ̂ boosters (MED)

3, 17-element 93% 2 3 5U boosters at LM0, JK2E, JK2W

61-element 93% 2 3 5U booster at K0 (in lattice 28-10)

ModeratorCriticalHeight

(cm)

211.692

183.858

234.163

194.148

195.940

192.632

191.160

231.321

159.032

170.425

184.218

188.215

216.360

166.050

186.429

203.974

Temp.

(°C)

21.96

21.71

21.01

20.95

21.24

21.40

21.46

21.46

21.16

21.48

21.58

20.09

21.46

21.35

21.37

20.95

Purity

(atom % D2O)

99.544

99.544

99.560

99.554

99.468

99.537

99.470

99.536

99.536

99.536

99.536

99.462

99.535

99.535

99.459

99.341

toto

(a) Simultaneous irradiation with fine structure detectors.

(b) All boosters D2O cooled.

- 24 -

of the open center square lattices. The low enrichment

booster was also located perpendicular to the fuel at

an elevation of 80.0 cm along the reactor east-west

diameter (K direction) in the 28.58 cm, D20 cooled lattice

'Figure 9) .

In most of these experiments, both r and T were deter-

mined at the following representative locations throughout

the core:

1. Inside booster fuel elements (Figure 7)

between fuel pellets (low enrichment

booster only).

2. Inside reference fuel elements (Figure 1)

between fuel pellets at rod site JK1E.

3. At the surface of booster fuel elements

(Figures 4 and 7).

4. At the booster pressure tube surface.

5. At the calandria tube surface of selected

reference fuel assemblies.

6. At various moderator locations in the

central cells of the core, on thin Al

frame works (Figure 13).

7. At various moderator "cell edge" and

"cell corner" locations.

The thermal reference position was located at the reactor

calandria wall on the east-west reactor diameter, at least

- 68 cm from the reactor core.

In the perpendicular booster case, measurements were

also made along the length of the booster, and axial spectral

measurements were made at neighboring reference fuel and

moderator cell edge locations.

A spectral detector comparison experiment was done with

- 25 -

the high enrichment booster vertical at lattice site KO

in the 28.58 cm pitch, D2O cooled lattice. Measurements

were also made in the reference fuel elements, on the

sheath of reference fuel elements and booster elements,

on booster pressure tube and reference calandria tube

surfaces, and at various thimble locations near the

booster.

3.3.2 Measurements with Interacting Boosters

The booster interaction experiments consisted of measure-

ments with three, 33-element, D2O cooled, high enrichment

boosters inserted interstitially (equidistant from three

neighboring fuel assemblies) in a 30.00 cm hexagonal D2O

cooled reference lattice. Three booster separation con-

figurations were studied, representing different degrees

of booster coupling. The booster spacing associated with

"tight" interactions was d, the reference lattice pitch

(30.00 cm); the " medium " interaction separation distance

was 2d; the separation associated with "loose" interaction

was 4d. The boosters were situated symmetrically about the

reactor center, as shown in Figure 14.

The boosters were inadvertently mispositioned in the

loose configuration (two were at lattice sites IJ3E and

IJ3W instead of IJ4E and IJ4W). This asymmetric configu-

ration did not affect detailed measurements near the

booster cell at lattice site MN0, but macroscopic effects

in the core were remeasured with the boosters symmetric.

Lattice void effects with and without three 33-element

D2O cooled boosters at the medium, 2d separation, were

investigated by voiding the central 19 reference fuel

assemblies of the hexagonal reference lattice.

BOOSTER SEPARATION

30 CM 6 0 CM120 CM

O O Oo o o o o o

o o o o o o oo oo o o#6#o o o

o o o o o o o oo o o o o o oo o o o o o

o o o


o o c*o o*o o o o o o o o o o I

O 28-ELEMENT, U0 2 (DgO COOLED) REFERENCE ASSEMBLY

• 33-ELEMENT INTERACTION BOOSTER ROD

Fig. 14 Lattice configurations with three interacting boostersparallel to reference fuel assemblies

- 27 -

Measurements were made with three, 17-element, DZO

cooled, high enrichment boosters at the medium (2d)

separation configuration in the hexagonal lattice. Measure-

ments were also made with these three boosters perpendicular

to the fuel assemblies in the 28.58 cm square, D20 cooled

reference lattice, as shown in Figure 15. Reactor safety

considerations precluded the use of the more reactive 33-

element boosters. Two boosters were positioned east-west

in the core, along lattice co-ordinates J and L, and were

suspended 30.5 cm from the floor of the reactor calandria.

The booster along the east-west diameter at lattice

co-ordinate K was suspended 80.0 cm from the calandria

floor. The resulting configuration was equilateral with

booster separation equal to twice the lattice pitch (2d =

57.15 cm); the boosters were symmetric about the north-

south diametral plane. For safety considerations, all

boosters were suspended below the expected position of

maximum axial importance.

The spectral parameter r/T /T was measured at most of ther novarious core locations described in Section 3.3.1; however,

detailed booster cell moderator measurements (on the Al

framework) were not done. The thermal reference position

was located at the south reactor calandria wall, ~ 64 cm

from the reactor core.

3.3.3 Reference Lattice Measurements

Spectral parameter measurements were made at represen-

tative locations in the three reference lattices to provide

a set of reference results without the booster perturbations.

Measurements were also made in the 30.00 cm pitch, hexagonal

D20 cooled reference lattice with the central 19 assemblies

voided.

- 28 -

RADIAL POSITION

J K L

I I II I II I I

28.58 CM

O

u

2 8 - ELEMENT FUEL

H,

(~ I9O CM)

80.0 CM

30.5

15.0

0 CM

BOOSTER

Fig. 15 3, 17-element boosters - horizontalconfiguration in ZED-2

- 29 -

4. RESULTS AND DISCUSSION

The Westcott spectral parameters r^T /T , r, and Tno n

were determined from detector activities as discussed in

Section 3.1. The specific activity ratios, relative

to the thermal reference location arid the derived spectral

parameters are listed in the detailed tables of results

in this section and in the appendices. In most cases,

the errors shown were determined by assuming a + 0.5%

error in the determination of detector activities.

The alphameric labelling of detector locations in the

core is based on the co-ordinate system shown in Figures

2 and 3.

4.1 61-Element Booster Results

4.1.1 Boosters Parallel to Reference Fuel Assemblies

Detailed spectral results in the central cells of the

lattices from measurements on the Al frameworks, on booster

and reference assembly pressure tube and calandria tube

surfaces, and in thimbles are listed in Tables 2 to 6.

The results in a direction south-east from the lattice

centers are shown in Figures 16 to 20. Also shown are booster

fuel pin sheath surface averages and reference fuel average

values. Macroscopic spectral results are tabulated in

Appendix B. Booster fuel pin mean, sheath surface mean,

reference fuel pin mean, and spectral results at represen-

/ative lattice sites are listed in Table 7 to facilitate

direct comparison between the experimental configurations.

With the exception of Case 28-10, measurements in the

28-element reference fuel pins were made with Au detectors.

- 30 -

I I I II I I J I LLUI I

LATTICE SITEJ2E

\

I I ' '28 30 32 54

J L.0 2 4 6 B 5 12 1 4 1 6 I B 20 22 24 26

CORE RADIUS (cm)36 38 40

li 1 ' '

OETECTORS:• 0.775cm DIAMETER AU-AL.LU-AL, 8 CU• 1.422cm DIAMETER AU-AL.LU-AL, 8 CUX 0.5 cm All B CU STRIPS (SHEATH)

-ROD JKIE-

J L.

SE

LATTICE SITEJ 2 E '

10 12 14 16 IS 20 22 24 26 28 30 32 34 36 38 40

CORE RADIUS (cm)

Fig. 17 r/T /T SE of lattice center? Case 28-20

- 31 -

0.13-

0.12 -

Oil -

' S

0.10-

Q09 -

Q08-

\

\

\

Q0S-—BOOSTER-

DETECTORS:

X OS cm AU a CU STRIPS• 0.775 cm DIAMETER AU-AL a CU• 1.422 cm DIAMETER AU-ALB CU

-ROD JKIE •

LATTICE SITEJ2E

IS 18 20 22 24 26 28 30 32 34 36 38 40

CORE RADIUS (cm I

Fig. 18 r/T /T SE of lattice center:n o Case 28-30

TABLE 2

MEASURED NEUTBOH SPECTRUM PARAMETEBS IN A LATTICE CELL

CASE 28-10: 28.SB cm (DjO)Reference Lattice

Detectorla|Location

Mod.

Cal. S.Fuel (°>

Cal. S.Mod.

Hod.Cal. E.Hod.

Cal. s.Hod.

Thermal Pit

MeasurementPosition

(cm)

0.0216.B4

13.8416.0017.5619.0521.3722.8624.4226.5833.5340.489.996.37

10.5214.476.37

10.5714.29

Position MeasuredFrom

Lattice centerLattice Center

Lattice CenterCenter of Rod JKIE

Center of Rod JKIE

irection

HHSE

EH

S

In/Mn lb|

Act. Ratio

1.359 + .0141.410 7 .0141.526 + .0151.705 7 .0171.B75 7 .0191.922 7 .0191.940 7 .0191.855 7 .0191.728 7 .0171.519 7 .0151.3B4 7 .0141.356 + .0141.403 7 ,0141.532 7 .0011.436 7 .0141.427 7 .0141.536 " .0151.424 7 .0141.419 7 .014

l.Eoo

(c)

0.022 + .0010.025 7 .0010.032 7 .0010.043 7 .0010.053 7 .0010.056 7 .0010.058 7 .0010.052 7 .0010.044 7 .0010,031 7 ,0010.023 7 .0010.021 7 .0010.024 7 .0010.032 7 .0010.026 " .0010.026 7 .0010.032 7 .0010.026 + .0010.025 + .0010.1B4 X lO-3

LU/Mn lblAct. Ratio

1.046 + .0101.053 7 .0111.078 7 .0111.180 7 .0121.273 7 .0131.264 7 .0131.2B0 7 .0131.250 7 .0131.189 7 .0121.083 7 .0111.029 7 ,0101.029 7 .0101.023 7 .0101.090 7 .0111.047 7 .0101.045 7 .0101.092 7 .0111.027 7 .0101.038 7 .010

l.ffoo

r

0.0210.0240.0310.0390.0470.0500.0510.0460.0400.0300.0230.0210.0240,0310,0260.0250.0310.0250.025

Tn

32 + 334 + 341 + 371 7 4

101 7 599 + 5

105 7 593 + 574 7 443 7 328 7 328 T 326 + 345 7 332 7 332 + 3«5 7 427 7 330 +" 321701

Method

(d)

(a)

(b)

Mod,, Cal. s.y and Fuel refer to detoctor locations in the moderator, on a calandria tube surface, and in thafuel pins, respectively.In/Mn or LU/Mn ratloB are ratios at the measurement position, relative to the same ratio at the thannal pitlocation. The r^Tn/To value reported at the thermal pit W B B determined from a Cd ratio method wLth In foils.

D2O 21.01OC.(dl 1.422 cm diameter Lu-Mn-Al and Xr.-Al foil packages,(e) Measurement positions quoted for fuel are distances meaBurttd from the lattice center, SE to the appropriate

fuel ring radii.

- 32 -

MEASURED NEUTBON SPECTRUM PARAMETERS IM A PERTURBED LATTICE CELL

CASE 28-20. 28.58 cm (D2O) Reference Lattice61-element 20% 2' SU Booster at K0

DetectorLocation

Booster

Booster

BoasterMod.Cal. s .Puol(e)

Cal. S.Mod.

BoosterMod.

Cal. S.Mod.

Cal. s.Mod

Thermal

F

S

P

P

la)

(e)

(e)

T.

T.

P i t

MeasurementPosition

(cm)

0.001.272.463.853.854.914.914.910.001.272.463.S53.354.914.914.915.729.78

13. e416.0017.5619.0521.3722.8624.4226.5833.5340.475.729.97

14.326.37

10.3714.296.37

10.5714.29

Position MeasuredProm

Lattice Center

Lattice Center

Center of rod JK1E

Center of rod JK1E

quivalehi)lrection

SE

E

N

S

Au/Cu(e)Act. Ratio

2.8392.8662.7402.6032.6202.4212.4462.4601.7901.7781.7311.6561.6S71.6391.5911.6012.2601.9431.8831.9391.9461.9161.8641.7741.6851.6041.4261.3832.2211.B701.7111.7921.6871.6861.6041.4961.454

1

+77I+7777+++777+7+7++77++777++TT77777

.038

.038

.036

.034

.035

.032

.032

.033

.018

.018

.017

.017

.017

.016

.016

.016

.030

.026

.025

.019

.019

.019

.019

.018

.017

.021

.019

.018

.029

.025

.023

.024

.022

.022

.021

.020

.019000

r/T"

0.1240,1260,1170.1070,1080,0940,0960.0970.1040.1030,0960.0860,0900.0840.0780.0790.0830.0620.0580.0610.0620.0600.0560.0500.0440.0390.0280.0250.0810.0570.0460.0520.0450.0450.0390.0320.0300.950

7*oW1

+ .003+ .0037 .0037 .002+• .002+ .002+• .0027 .0027 .0027 .002+ .002+ .002+ .0027 .002+ .002+ .002+" .0027 .002+ .002+ .001+ .001+ .001+ .001+ .001+ .001+ .001+ .001+ .001+• .0027 .002T .001+" .002+ .001+ .001+ .001+ .001+ .001ic 10-3

LU/CU "='Act. Ratio

1.260 + .0171.280 + .0171.259 + .0171.240 + .0161.248 +" .0171.220 + .0161.200 + .0161.204 + .016

""

1.158 + .0151.104 7 .0151.143 7 .0151.228 7 .0121.272 + .0131.312 7 .0131.304 7 .0131.264 7 .0131.217 + .0121.124 7 .0151.059 7 .0141.069 7 .0141.152 + .0151.101 T .0151.087 T .0141.135 7 .0151.077 7 .0141.092 7 .0141.117 7 .0151.067 7 .0141.054 + ,014

i.ffoo

I

0.1080.1080.1020.0950.0950.0850.0870.087

0.0770.0590.0540.0550.0550.0520.0490.0450.0400.0370.0270.0240.0750.0540.0450.0490.0430.0430.0370.0310.029

(OC,

115 + 11124 + 12112 " 10102 7 9106 7 10

92 + 885 7 e87 7 B

68 + 749 + 560 + 667 + 5

101 + 5112 + 5109 + 595 + 581 + 45J + 535 + 438 + 46 6 + 747 T 543 T 558 + 540 + 544 + 552 + 537 + 434 + 4

20795

Method

If)

(9)

If)

(h)

IC)

(b)

Ic)

Idl

le!

If)

Booster F., Booster S., Booster P.T., Hod., Cal. s., and Fuel refer to detector locations in thebooster fuel pins, on booster fuel pin sheaths, on the booster pressure tube, in the moderator, ona reference assembly calandria surface, and in the reference assembly fuel pins, respectively.

Reported spectrum parameters in direction B and SE from the lattice center were obtained in partfrom measurements in equivalent directions N and NE.

Au/Cu or Lu/Cu ratios are ratios at the measurement position, relative to the same ratio at thethermal pit location. The r»Tn7T3 value reported at the thermal pit was determined from a Cdratio method with In foils.

To = T D 2 0 = 20.95OC,

Measurement positions reported are distances measured from the lattice center, SE to theappropriate booster or fuel ring radii.

0.775 cm diameter Au-Al, Lu-Al, and cu foil packages.

0.5 cm wide Au and Cu strips wrapped around sheath.

1.422 cm diameter Au-Al, Lu-Al and Cu foil packages.

- 33 -

MEASURED NEUTRON SPECTRUM PARAHETER5 IN A PERTURBED LATTICE CELLCASE 2B-301 28.5B cm (D20) Deference Lottie

Gl-element 931 l l su Booster at ]

Detectorlal

Location

Booster s!0'

Booster P.T.Hod.Cal. S.Fuel(e)

Cal. s.Hod.

Booster P.T.

Hod.

Cal. s.

Mod.

cal. S.Hod.

Thermal Pit

HaaaurementPosition(cm)

0.001.152.223.313.314.434,435.729.7813. B416.0017.5619.0519.0519. OS21.3721.3721.3722.8624.4226.5633.5340.475.725.7Z5.729.97

14.326.376.376.3710.3714.2914.2914.296.37

10.5714.29


Lattice Center

Lattice Center

Center of rod JK1E

Center of rod JK1E

quivaleMDirection

SE

£

N

S

In/Mn or'01

Au/cuAct. Ratio

1.713 + .01B1.7B1 + .0181.723 + .0171.690 X .0171.679 X .0171.591 T .0161.607 + .0162.071 X .0271.7B3 + .0241.753 7 .0231.8B6 X .0191.911 + .0191.686 + .0191.902 + .0192.269 + .0231.835 + .0181.B22 + .0182.181 - .0221.739 + .0171.655 + :0171.538 + .0201.375 + .0181.338 + .0182.060 + .0272.106 + ,0212.058 + .0211.767 + .0231.611 + .0211.698 ~ .0221.739 + .0171.797 + .0181.599 + .0211.613 + .0211.645 + .0161.647 X .0171.552 + .0211.435 T .0191.405 + .019

i.ffoo

0.1050,1030.0950.0910.0890.0780.0800.0710.0510.0490.0500.0600.0580.0590.0790.0550.0540.0730.0480.0430.0350.0250.0220.0700.0730.0650.0500.0400.0460.0480.0490.0 J90.0400.0420.0400.0360.0290.0270.127

+++

XX7XX77777777777777+777777777777777X

(HI

.002

.002

.002

.002

.002

.002

.002

.002

.002

.002

.001

.001

.001

.001

.002

.001

.001

.001

.001

.001

.001

.001

.001

.002

.001

.001

.002

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.00110-3

Lu/Hn orLu/Cu

(c)

Act. Ratio

1.2801.300

1.2931.289

1.1321.131

1.1401.133

1.070

1

+7~+_7

+7

+

+

.013

.013

.013

.013

.011

.011

.011

.on

.011

000

00

00

00

00

0

r

.052

.068

.047

.064

.069

.061

.045

.046

.038

Tn

- 34 -

0046

0.046 "

O044-

OETECTORS:0.775 cm DIAMETER AU-AL.LU-AL 8 CU

1.422 cm DIAMETER AU-AL.LU-ALBCU

-ROD JKIE-

(r,/Tn/Tol- = 0.04S

J L16 IB 20 22 24 26 28 30 32 34 36 38

CORE RADIUS (cm)

BOOSTER

lr./Tn/TolF =0.108

(r./Tn/To)s =0.093

DETECTORS:

• 0.775 cm DIAMETER AU-AL, LU-AL, a CU• 1.422 cm DIAMETER AU-AL, LU-AL, a CUX 0.5 cm AU 8 CU STRIPS (SHEATH)

ROD JKIE

(r,/Tn/To)F = 0.057

LATTICE SITEJ 2 E 1

SE

10 12 16 18 20 22

CORE RADIUS (cm)24 ?6 26 30 32 34 36 38

- 35 -

MEASURED NEUTRON SPECTRUM PARAMETERS IH A LATTICE CELL

CASE 27-10: 27.94 cm (AIR) Reference Lattice

Detector(°'Location

Hod.

Cal. s,Fuel Id)

Cal. S.Mod.

Cal. s.Hod.

Cal. s.Hod.

ThermalPit

MeasurementPosition

(cm)

0.016.44

13.3915.5517.1118.5920.9222.4123.9626.1333.0839.476.37

10.5213.926.37

10.5713.9?


Lattice Center

Center of rod JK1E

Center of rod JK1E

irection

SE

N

S

AU/Cu lb>Act. Ratio

1.407 + .0141.429 + .0141.569 + .0161.656 + .0171.724 • .0171.724 + .0171.717 + .0171.708 + .0171.663 + .0171.553 + .0161.436 + .0141.405 + .0141.579 + .0161.4B4 + .0151.463 + .0151.579 + .0161.477 + .0151.452 + .015

1.000

0.027 + .0010.028 + .0010.037 + .0010,043 * .0010.047 + .0010.047 + .0010.047 + .0010.046 + .0010.043 + .0020.036 + .001U.029 7 .0010.027 + .0010.038 + ,0010.036 + .0010.030 + .0010.038 + .0010.031 + .0010.030 + .0010.135 X 10-3

Lu/Cu lb)Act. Ratio

1.060 -I1.062 41.146 31.218 i1.291 i1.30G 51.297 51.268 i1.213 H1.141 11.060 '1.062 "1.141 "1.0781.065 '1.1401.0751.068

1.

.011' .011' .011' .012" .029" .013' .013" .013' .021" .011' .011" .011F .011F .011F .011F .011F .011[ .011100

r

0.0260.0270.0350.0390.0420.0410.0410.0410.0390.0340.0280.0260.0350.0310.0290.0350.0300.029

°C

36 + 337 + 36 1 + 482 + 4

104 + 5Ilia + 5106 + 597 + 58 1 + 460 + 437 • 337 + 360 + 442 + 338 + 359 + 441 + 339 + 3

21.96

Method

(e)

(f)

(e)

(a)

(b)

(c)

(d)

(e)

(fl

Mod.f Cal. s., and Fuel refer to detector locations in the moderator, an a Calandria tube surface, andin the fuel pins respectively.

Au/Cu or Lu/Cu ratios are ratios at the measurement position, relative to the same ratio at the thermalpit location. The rVTn/To value reported at the thermal pit was determined from a Cd ratio methodwith In foils.

'D2O21.96

Measurement distances quoted for fuel are distances, measured from the lattice center, SE to theappropriate fuel ring radii.

0.775 cm diameter Au-Al, Lu-Al and Cu foil packages.

1.422 cm diameter Au-Al. Lu-Al and Cu foil packages.

- 36 -

TABLE 6

MEASURED NEUTRON SPECTRUM PARAMETERS IN A PERTURBED LATTICE CELL0: 27.94 cm (AIR) Reference Lattice

61-element 20* ) J SU Booster at KO

Location

Booster F . ( e J

Booster S. ' eJ

booster P.T.Mod,Cal. S.Fuel (e)

Mod.

Booster P.T.Mod.

c a l . S.Mod.

cal. s.Mod.

Thermal P i t

Posi t ionIcm)

0.001.272.463.853.B54.914.914.910.001.272.463.B53.854.914.914.915.729.33

13.3915.5517.1118.5920.9222.4123.9633.0839.475.729.97

13.976.37

10.3713.976.37

10.5713.97

From

Latt ice Center

Lat t ice center

Center of rod JK1E

Center of rod JK1E

(b)

Direction

SE

E

N

S

cl

Act. Ratio

2.909 +2.864 *2.754 +2.606 +2.646 +2.465 +2,464 +2.471 •1.B36 +1.816 ?1.760 +1.713 +1.713 +1.646 "1.632 •1.651 +2.283 +1.960 +1.915 +1.971 +1.979 +1.946 t1.891 T1.B30 +1.735 +1.452 +1.409 +2.265 +1.885 +1.727 +1.848 T1.742 +1.729 +1.679 +1.510 +1.471 *

.029

.029

.028

.026

.026

.025

.025

.025

.018• 01B.018.017.017.016.016.017. 0 2 3. 0 2 0.019.020. 0 2 0.020.019. 0 1 8.017. 0 1 5.014. 0 2 3. 0 1 9. 0 1 7. 0 1 8.017.017.017. 0 1 5. 0 1 5

1.000

r Tn

0.1290.1260.1180.1070.1100.0970.0970.09B0.1100.1080.1010,0940.0940.0850.083O.0B60.0S40.0630.0600.0640.0640.0620.0580.0540.04f0.03J0.0270.0840.05S0.0470.0550.0480.0480.0440.0330.0310.104

* .002+ .002+ .002+ .002* .002+ .002• .002T .002+ .002+ .002~ .003+ .002+ .002T .002+ ,002+ .002+ .002+ .001+ ,001• .001+ .001T .001+ .001+ .001+ .001+ .001+ .001T .002+ .001+ .001+ .001+ .001+ .001+ .001+ .001+ .001X 10-3

(c)Lu/Cu •"'Act. Ratio

1.281 + .0171.279 + .0171.269 5 .0171.240 + .0161.264 T .0171.201 i1.222 5

" .016" .016

1.198 T .016

1.777 i .0161.116 + .0151.186 "1.224 i1.261 i1.271 '1.269 "1.246 :1.201 "1.063 "1.069 "1.166 51.0941.0771.170 51.093 "1.084 "1.163 51.080 "

.016" .012" .013F .013F .013" .012F .012F .014F .014F .015F .014• .014" .015F .014F .014" .015F .014

1.070 T .014l.ffoo

r

0.1110.1080.1020.0950.0960.08B0.087O.0B8

0.0780.0600,0550.0b70.0570.0550.0520.0480.0440.0290.0260.0770.0560.0460.0510.0460.0460.0410.0320.030

*

127124 H118 H104 1113 '•

87 :

94 '86 '

1211

" 10' 9

10' a

7 6 + 753 + 67 3 + 6Ub +" 599 ^ 3

102 T S100 + •»

92 " • i7 8 + 43 7 + 439 + if.72 " : -t4 6 + 541 T 570 4 ft46 i- Q43 + 566 +" i4239

2 1 "

" 5' 4"71

Method

(g)

(h)

. . .*

(g)

(i)

(g)

(d)(ej

(hi

(i)

Booster P., Booster S., Booster P.T., Hod., Cal.S. and Fuel refer to detector locationsin the booster fuel pins, on booster fuel pin sheaths, on the booster pressure tube,in the moderator,on a reference assembly calandria surface, and in the referenceassembly fuel pins, respectively.

Reported spectrum parameters in directions E and SE from the lattice center were obtainedin part from measurements in equivalent directions N and NE.

Au/Cu of Lu/Cu ratios are ratios at the measurement position, relative to the same ratioat the thermal pit location. The r/Tn/To value reported at the thermal pit was determinedfrom a Cd ratio method with In foils.T ° " TD 2O * " - ' I " * -Measurement positions reported on distances measured from the lattice center, SE to theappropriate booster or Fuel ring radii.The paraithe pin.

eters at this position are estimates based on the parameters measured insideThe strips on the sheath were loose during irradiatiun.

0.775 cm diameter Au-Al, Lu-Al and Cu foil packages.0.5 cm wide Au and Cu strips wrapped around sheath.1.422 cm diameter Au-Al, Lu-Al and Cu foil packages.

- 37 -

TABLE 7

MEASURED NEUTRON SPECTRUM PARAMETERS

COHPAHISQH OF SQUARE LATTICE VERTICAL BOOSTER RESULTS

Experiment andMeasurement

CORE LOCATION

BoaBter Fue lPin Mean a t

KO

Booster Sheatqlurface Mean

a t KO

ReferenceFuel pin Meanat JK1E

Booster Preo-•urs Tube Sur-|face Mean at

Ref. Calandria|Surface Mean

at JK1E

K1WPerturbed Celi)

Edge

J2WUnperturbedCell Corner

:ase 28-1Q

B.5B cm (D-1. r^V^3! Tn(°C>

CaaB 2B-20

iO) Ref. Lattice

IB.58 cm ID2O) Kef. l a t t i ceA 61-element 201 • "UBooster a t KO

1. r/T^IS2. r3 . Tn(OC)

1 28-30

0.107 + .0020.094

101 + 6

1.58 cm (D2O) Ref. Lattice61-element 93% I ! i U

1 Booster at K0

1. srpr;

7.94 em (Mr) Bef. Lattice1. r/T_/To2. r3. T (°CI

27.94 cm (AirJ He£. Latticei 61-element 20% " ! 0iBooster a t K0

^7%

Tn(°C>

0.10B i .00.O95

105 • 6

0.048 -*- .00.043

B4 + 5

0.054 ± .00.049

92 + 5

0.052 * .001

O.045 + .0010.040

91 + 5

0.057 + .0010.052

89 + 5

0.082 + .010.07S ~

67 + 7

0.071 + .002

0.0S4 + .0020.078 ~

74 4 7

0.U32 + .0010.D31 ~

44 + 3

0.0260.025

35

0.024 +0.023 "

34 T

0.044 "56 + 5

0.037 + .010.035

60 + 4

0.051 + .0010.047 ~

69 + 6

0.029 + .00.02B ~

3B + 3

0.048 + .0010.046 "

46 + 5

0.024 ~32 +

0.022 + .001

0.0270.026 '

0.02B + .0010.027

39 + 4

(a) Detectors UBed were Au( Lu and Cu except Case 26-10 (In, Lu and Hn) t

(b) cd r a t i o measurement with In-Al f o i l s .

- 38 -

The nearness of the major Au resonance (4.91 eV) to a

large 2 3 8U resonance (6.68 eV) significantly depressed

the Au activation, and thus (r/Tn/TQ) Au values in the

reference fuel are low relative to a similar measurement

with In. The unperturbed, air cooled reference lattice

(Case 27-10; Au detectors) shows considerable spectral

flattening in the fuel when compared with the D2O cooled

lattice (Case 28-10; In detectors). Thus the measurements

indicate a higher fuel average in the D2O lattice but in

fact the reverse was correct; results at other core locations

show that the spectrum was harder in the air cooled core.

This effect is discussed more fully in Section 4.3.

Spectral perturbation effects were represented more

clearly by defining a "spectral perturbation factor",(12)S(r,z) similar to the flux perturbation factor :

. _ _j_ ii yj i. ,*. / xi w j Perturbed lattice

f(r /T /T ) / (r/T /T ) R,zl Unperturbed latticeL n o r, z / n o J r

where r,z refers to a core location with co-ordinates

(r,z) and R,Z is a core location removed from the spectral

perturbation (lattice site J2E).

Spectral perturbation factors S(r) are tabulated in

Appendix C and shown in Figures 21 to 23. The axial depen-

dence was not considered since r/T /T values were constantn o

over the central part of the core where the measurementswere made. The reference lattice Case 28-10 (r/T /T ) T

n o Invalues were converted to (r/T /T ). as discussed in Section

n o Au

4.3, to ensure a consistent set of S(r) values in the

28.58 cm, D20 cooled lattices. The results indicate that

spectral perturbations introduced by the boosters do not

- 39 -

SE

- R O D J K I E -

_j I i

X SURFACE OF BOOSTER FUEL PIN SHEATH

• BOOSTER FUEL

LATTICE SITE

J 2 E '

O 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 31 36 38 40CORE RADIUS (cm)

Fig. 21 Spectral perturbation factors SE of latticecenter: Case 28-20

O 2 4 6 8 io 12 14 16 IB SO 22 2 4 2 6 2B M M 3 4 36 38 4 0

CORE RADIUS (cm)


- 40 -

X SURFACE OF BOOSTER FUEL PIN SHEATH

• BOOSTER FUEL

L _ l U] I ' ' II II I 1 I I 1 II I 1 110 12 14 IS 18 20 22 24 26 28 30 32 34 36 380 2 4


extend much more than one lattice pitch (~ two or three

slowing down lengths) from the booster site; the spectral

perturbation factor curves decrease smoothly toward 1.0

at lattice site J2E.

Examination of the results indicate that as expected,

the spectrum with the low enrichment booster in the 27.94 cm,

air cooled lattice was everywhere slightly harder than the

spectrum with the same booster in the D2O cooled lattice.

The spectral perturbation factors, however, were identical

within experimental error.

- 41 -

In the 28.58 cm, D20 cooled lattices, r/f~7T~ valuesn o

in the central cells immediately surrounding the 20%

enriched booster were higher than corresponding values

with the 93% enriched booster. Since the235U loading was

the same in each booster (within 3%) the additional spectral

hardening with the low enrichment booster was likely due to

thermal and resonance absorption, and fast fission effects

in 2 3 8U. Within the 20% enriched booster, however, ther/T /T~ values inferred from the Au activations have beenn odepressed due to the presence of the 2 3 8U. Thus, at the

booster fuel pin sheaths, the results are the same in both

boosters.

4.1.2 Booster Perpendicular to Reference Fuel Assemblies

Macroscopic spectral effects in the 28.58 cm, D20

cooled lattice with the low enrichment booster perpendicular

to the reference fuel assemblies (Case 28-40) are listed

in Table 8 and axial effects are shown in Figure 24.

Results along the length of the booster, on the pressure

tube surface, are shown in Table 9.

Axial spectral perturbations, represented by S(r,z)

values at radial locations JK1E and JKO, are shown in

Table 10. The unperturbed normalization locations were

at 175 cm and 165 cm at radial locations JKlE and JKO

respectively.

- 42 -

TABLE 8

MEASURED NEUTRON SPECTRUM PARAMETERS IN LATTICE

CASE 28-40: 28.58 cm (DyO) Reference Lattice

61-element 20% 235U Booster Perpendicularalong K at 80 cm elevation.

JK1E

IJ3E

JK3W

JK7W

JKO

JK4W

I4E

LOLMOMNO

Core Location

Location

Calandria Surface (West)

Calandria Surface (NW)

Calandria Surface (E)

Calandria Surface (E)

Thermal Pit

Elevation

(cm)

1751S513511595755535

1157511575

11575165145125105856545

1157511575757575

(a) The reported activity ratios areposition relative

Au/CuAct.

1.5471.5361.5511.5451.6571.7651.5951.5181.5301.5281.5311.7951.5111.6481.4141.4231.4301.4571.6401.5481.4421.4521.6651.3801.3691.4181.4341.436

1

ratiosto the same ratio at 1

location. The r/Tn/To value atdetermined by a Cd ratio method

(b) 0.775 cm diameter

the reftwith In

Ratio

+ .015+ .015+ .015+ .015+ .017+ .018+ .016+ .015+ .015+ .015+ .015+ .018+ .015+ .016+ .014+ .014+ .014+ .015+ .016+ .016+ .014+ .015+ .017+ .014+ .014+ .014+ .014+ .014ffoo

r/T /Tn o

0.036 +0.035 +0.036 +0.036 +0.043 +0.050 +0.039 +0.034 +0.035 +0.035 +0.035 +0.052 +0.034 +0.043 +0.027 +0.028 +0.028 +0.030 +0.042 +0.036 +0.029 +0.030 +0.044 +0.025 +0.024 +0.028 +0.029 +0.029 +0.256 x

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001• 00110" 3

Method

(b)

at the measurementthe thermal pitTence position wasfoils.

Au-Al and Cu foil packages.

- 43 -

TABLE 9

MEASURED NEUTRON SPECTRUM PARAMETERS AT BOOSTER ROD

CASE 28-40: 28.58 cm (D2O) Reference Lattice

61-element 20% 2 3 5U Booster Perpendicularalong K at 80 cm elevation.

Distance From Centerof Perpendicular

Booster(cm)

5.0

20.0

35.0

50.0

65.0

80.0 , •

95.0

Direction

East

Au/CuAct.

2.158

2.176

2.130

2.142

2.153

2.093

1.669

(h)

Ratio

+ .022

+ .022

+ .021

+ .021

+ .022

+ .021

+ .017

0.077

0.078

0.072

0.076

0.076

0.072

0.044

+

+

+

+

+

+

+

.001

.001

.001

.001

.001

.001

.001

(a) Booster perpendicular along K direction at 85.0 cm elevation.Detectors located on top of booster pressure tube at 90.7 cmelevation.

(b) The reported activity ratios are ratios at the measurementposition, relative to the same ratio at the thermal pit location.The r/T /T_ value at the reference position was determined by aCd ratio method with In foils. The detectors were 0.775 cmdiameter Au-Al and Cu foil packages.

_ 44 -

0.050

0,046-

0.046-

0.044-

0.042-

0.040-

0.038-

0.036-

0.034

O032

0.030

0.028

0.775 cm DIAMETER AU-AL a CU DETECTORS

JKIE CALANDRIA SURHCE(WEST SIDE)

THIMBLE JKO

20 60 80 100 120

ELEVATION IN CORE (em)

140 160 ISO

TABLE 10

AXIAL SPECTRAL PERTURBATIONS. S ( r . z )

CASE 28-40: 28 .58 cm |D 20)Reference L a t t i c e61-e lement 20% JJI1U Boosterperpendicular along R a t 80 cm e l e v a t i o n

Core Location

JK1E CalandriaSurface (west)

Elevation(cm)

175

155

135

115

95

75

55

35

S(r,z)+ 5*

1.00

1.00

1.00

1.00

1.19

1.39

1.08

1.00

Core Location

JKO

Elevation(cm)

165

145

125

105

85

65

45

S(r,z)+ 5*

1.00

1.00

1.00

1.07

1.50

1.29

1.00

- 45 -

4.2 Interacting Booster Results

4.2.1 Boosters Parallel to Reference Fuel Assemblies

Detailed spectral results in the hexagonal 30.00 cm,

D2O cooled cores with and without three, 33-element inter-

acting boosters parallel to the reference assemblies are

tabulated in Appendix D. To facilitate direct comparison

between the experiments, results in the booster and reference

fuel bundles, and at representation lattice sites are shown

in Table 11.

In a few cases, r/T /T values at the booster fuel pinno c

sheath surfaces, determined with Au and Cu strips, did not

seem consistent with Au-Al and Cu foil measurements. Com-

parison of results between experiments suggested that the

thermal reference Au-Cu strip activity determination was in

error in Cases 30-24, 30-32, and 30-65 and the results have

been modified. Inconsistencies were not resolved in Case

30-52D and no adjustments were made. Larger errors have

been assigned to the strip r/Tn/TQ values in these cases to

reflect this uncertainty.

Here again, spectral perturbations did not extend much

more than one lattice pitch from the booster sites. The

central reference fuel assembly was essentially unperturbed

for all configurations except the tightest booster spacing

(booster pitch = 30.00 cm). In this case, the close

coupling between the boosters resulted in a very large

fuel average (r/Tn/TQ)Au value (0.076).

MEASURED NEUTRON SPECTRUM PARAMETERS

COMPARISON OF HEXAGONAL LATTICE RESULTS

Case

EXPERIMENT

30-10

30.00 cm (DjO) Ref. Lattice

Case 30-24

30.00 cm (D_o) Ref. Lattice

s 3,' JK1E

Case

33-element Boasters (KL0,JKlw)

30-32

30.00 cm (D;,O} Ref. Lattice

& 3, 33-element Boosters (LMO,JK3E, JK2W)

Case 30-42 ( c )

30.OCS 3,IJ3E

Case

30.00with

Case

30.00with* 3,JK2B,

Case

30.00' 3,JK2E,

cm (Djo) Ref. Lattice33-element Boosters (HN0,

30-50E

cm (D20) Ref. LatticeCentral 19 rods voided

30-52D

cm (D2O) Ref. LatticeCentral 19 Rods voided33-eleoent Boosters (LMO,JK2H)

30-65

cm

- 47 -

4.2.2 Boosters Perpendicular to Reference Fuel Assemblies

Spectral results in the square 28.58 cm, D20 cooled

lattice with three, 17-element boosters perpendicular to

the reference fuel assemblies (Case 28.57) are listed in

Table 12 and axial effects are shown in Figure 25. Results

along the length of the central booster, on the pressure

tube, are shown in Table 13.

Axial spectral perturbations represented by S(r,z)

values at radial locations JKlE and JKO, are shown in

Table 14. The unperturbed, normalization locations were

at 135 cm and 165 cm at radial locations JKlE and JKO

respectively.

0.044 -

0O42 -

0.040 "

0.088 -

0036"

0O34-

0032-

0030"

0026-

0O26-

0.775 cm DIAMETER AU-AL 8 CU DETECTORS

JKlE CALANDRIA SURFACE(EAST SIDE)

THIMBLE JKO

oJ L

2 BOOSTERS'.ALONG J AND LDIRECTIONS

_ J L20 60 80 KM 120

ELEVATION IN CORE (cm)140

Fig. 25 Axial r/T /T : Case 28-57no

- 48 -

12

MEASURED NEUTRON SPECTRUM PARAMETERS IN LATTICE

CASE 28-57: 28.58 cm (DjO) Reference Lattice

3, 17-element Interaction BoostersPerpendicular (a).

Core Location

Location

JK1E Fuel: Outer Ring (W)Middle Ring (W)Inner Ring (W)Inner Ring (E)Middle Ring (E)Outer Ring (E)

Fuel Average

jKlf Caiandna Surface (East)

H U E Calandria Surface (E)IJ1E Calandria Surface (N)JK3W Calandria Surface (E)JK5W Calandria Surface (E)JK7W Calandria Surface (E)JKO

H6EI4EMOUNONONOOThermal Pit

Elevation(cm)

48.1

13b11595806545258080808080165145125105857565554535656565656565

Au/C„ (b)

Act. Ratio

1.6071.6851.7151.7291.6861.623

1.650

1.5091.5121.5791.6391.5621.5681.5541.5051.5141.6591.5821.6041.4061.4161.4141.4171.5021.5161.4651.4381.4701.5071.1141.3631.3671.4061.3621.406

1

+ .016+ .017+ .017+ .017+ .017+ .016

+ .010

+ .015+ .015+ .016+ .0167 .016+ .016+ .016+ .015+ .015+ .017+ .016+ .016+ .014+ .014+ .014+ .014+ .015+ .015+ .015+ .014+ .0157 .015+ .0117 .014+ .014+ .014+ .014+ .014.000

r/T /T

0.0400.0450.0470.0480.0450.0410.043

0.0330.0330.0380.0420.0370.0370.0360.0330.0340.0430.0380.0390.0270.0270.0270.0270.0330.0340.0300.0290,0310.0330.0080.0240.0240.0270.0240.0270.156

+1+1+

71+

l+l

++1+

+77771+

+

77777777777777771+

7+X

o

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.001

.ooi

.001

.001

.001

.001

.001

.001

.00110"J

Method

!O

Id)

(a) 2 boosters along J and L at 30.5 cm elevation and 1 boosteralong K direction at 80.0 cm elevation.

(b) The reported activity ratios are ratios at the measurementpositions, relative to the same ratio at the thermal pitlocation. The r/Tn/To value at the reference position wasdetermined by a Cd ratio method with In foils.

(c) 1.422 cm diameter Au-Al and Cu foil packages.

(d) 0.775 cm diameter Au-Al and Cu foil packages.

- 49 -

TABLE 13

MEASURED NEUTRON SPECTRUM PARAMETERS AT BOOSTER ROD

CASE 28-57: 28.58 cm

- 50 -

TABLE 14

AXIAL SPECTRAL PERTURBATIONS, S(r,z)

CASE 28-57: 28.58 cm (D2O)Reference Lattice

3, 17-element Interaction Boosters perpendicular(a)

Core Location

JK1E CalandriaSurface (East)

Elevation

135

1159S

8065

45

25

S(r,z)

+ 5»

1.00

1.00

1.15

1.27

1.12

1.12

1.09

Core Location

JK0

Elevation

165

145

125

105

8575

65

55

4535

S(r,z)+ 5*

1.00

1.00

1.00

1.00

1.22

1.26

1.11

1.07

1.15

1.22

(a) 2 boosters along J and L at 30.5 cm elevation and 1 booster alongK direction at 80.0 cm elevation.

- 51 -

4.3 Detector Normalization Experiment

The spectral results of the experiment in the 28.58 cm

D20 cooled square lattice, with the high enrichment booster

parallel to the fuel assemblies at lattice site KO, are

shown in Table £-1 in Appendix E. The 1.422 cm diameter

In-Al, Lu-Mn-Al foil package results are compared with the

results from 1.422 and 0.775 cm diameter Au-Al, I»u-Al and

Cu and Au-Al, Cu detector packages at various cell and

lattice sites near the center of the core.

At each location, the Au~Cu strips r/T1 /T results

were consistently about 10% higher than the corresponding

Au-Al foil package results. There is some uncertainty in

the determination of the resonance self shielding factor,

G , and since the resonance self shielding for pure Au

is high, it was concluded that the Gr value (0.483) was

in error. Thus the Au-Cu strip results were normalized

to agree with the Au-Al foil package results by adjusting

G and these normalized values are shown in the table.

The adjusted G for Au strips (0.524) was used in all

determinations of r/Tn/TQ in this report.

The results also show clearly the depression of the

Au detector r and r/T /T parameters, relative to In,n o r

in the vicinity of Z 3 8U. The effect is quite localized,

however. Large discrepancies occur within a 28-element

natural UO2 fuel bundle but at the UO2 assembly calandria

tube surface, no difference between methods could be

detected, within error.

- 52 -

At the booster fuel pin sheath surface, booster

pressure tube surface, and lattice sites KlE or K1W near

the booster, (r/Tn/TQ ) A u was higher than (r/Tn/TQ)In

The spectrum at the booster was very "hard" and the

higher measured spectrum with Au was presumably due to the

higher Au resonance energy (4.91 eV) compared with In (1.44 eV)

At moderator locations removed from the booster, spectral

parameters measured with Au or In were the same, within

experimental error. The neutron temperature, T , determined

by both methods agree within the large errors quoted.

The data from Table E-l was used to convert the r/T /Tn o

values determined with In (Table 2) to a set of values

corresponding to a Au measurement, for the 28.58 cm D2O

cooled reference lattice experiment (Case 28-10). These

adjusted values (Table E-2) were used to generate a con-

sistent set of spectral perturbation factors S(r) discussed

in Section 4.1.

- 53 -

5. SUMMARY AND CONCLUSIONS

Measurements were made in ZED-2 with four types of235U boosters. One type was nominally 20% enriched Z35u

(4.74 g 235U/cm length); the other three were 93%

enriched 2 3 5U with 235U loadings of 2.21, 3.49 and 4.88

g/cm length. The boosters were located interstitially,

parallel to reference fuel assemblies; in some experiments,

three boosters were inserted in three symmetric config-

urations that varied the flux coupling between boosters.

Experiments were also done with one or three booster

assemblies perpendicular to the reference assemblies.

Three reference lattice configurations were used.

Relative gold-copper, lutetiuro-copper or indium-

manganese, lutetium-manganese activity ratios were experimen-

tally determined in the regions surrounding the booster

assemblies. In some cases, detailed fine structure measure-

ments were made in the booster and neighboring reference

fuel assembly cells. These activity ratios were interpreted

in terms of Westcott spectrum parameters r and T or r/T /T .

The results show that spectral perturbation effects

did not extend much beyond one lattice pitch (two or three

lattice slowing down lengths) from a booster site, for all

configurations of one or three boosters studied. However,

the boosters were strong fast neutron sources and heavy

thermal' neutron sinks. In the immediate vicinity of the

boosters, and in neighboring reference fuel assemblies,

the spectrum was quite hard. The fuel pin average r/Tn/TQ

values of reference fuel assemblies nearest the boosters

were typically ~ 30% higher than when unperturbed. In one

case with three tightly spaced boosters around one reference

fuel assembly, the fuel average r/Tn/TQ was 80% higher.

- 54 -

The spectral perturbation introduced by the 20% enriched

booster was somewhat larger than theb of the 93% enriched

assembly (equivalent 2 3 5u content) due to additional

absorption and fast fission effects in the 2 3 8U.

These spectral parameter results, based on gold

activations, are depressed in the immediate vicinity of

fuels containing appreciable 238U since the major gold

resonance energy is close to a large Z 3 8U resonance.

Moreover, the results are not directly applicable to

power reactors due to differences in reactor configuration,

booster design, and operating conditions. Nevertheless,

the results can provide useful information for development

work with multi-group codes used to describe boosted cores.

- 55 -

ACKNOWLEDGEMENTS

The author wishes to thank the many people associatedwith the experiments and with the production of the report,in particular to P.D,J. Ferrigan, E. Pleau, and D. Robertswho helped perform the experiments, D.A. Kettner who countedthe detectors, Mrs. A. Bruin who prepared the diagrams andgraphs, and helped with the analysis and typing of tables,Mrs. G.D. Clark and Mrs. N.G. Hulbert who typed the text andtables, G. Stratford and S.L. Mehta who assisted with the analysisA.A. Pasanen and M.H.M. Roshd who suggested the experimentalprogram, A. Okazaki and R.E. Kay who gave advice during theanalysis, and E. Critoph who gave advice on the experimentalprogram and criticised the manuscript.

- 56 -

REFERENCES *

1. M.H.M. Roshd, "Gentilly BLW Booster Rod Experimentsin the ZED-2 Reactor", AECL-3258 (1969).

2. K.J. Serdula and R.E. Green, "Lattice Measurementswith 28-element Natural UO2 Fuel Assemblies - Part II :Relative Total Neutron Densities and Hyperfine ActivityDistributions in a Lattice Cell", AECL-2772 (1967).

3. R.E. Green and C.B. Bigham, "Lattice Parameter Measure-ments in ZED-2", Proc. IAEA Symp. Experimental andCritical Experiments^ Amsterdam (1963), II, 457-477(1964).

4. A. Okazaki, private communication (1971).

5. P. Purvis and W.R. Leach, Private Communication (1970)

6. C.H. Westcott, "Effective Cross Section Values for Well-moderated Thermal Reactor Spectra", AECL-1101 (1964).

7. C.B. Bigham et al., "Experimental Effective Fission CrossSections and Neutron Spectra in a Uranium Fuel Rod -Part II : CANDU-type Uranium Oxide Clusters", AECL-1350(1961).

8. S.L. Mehta, private communication (1970).

9. G.C. Hanna, "The Neutron Flux Perturbation Due to anAbsorbing Foil: A Comparison of Theories and Experi-ment", Nuc. Sci. Eng. JL5_, 325 (1963).

10. w.H. Walker et al., "Measurement of Radioactive CaptureResonance Integrals in a Thermal Reactor Spectrum, andthe Thermal Cross Section of Pu240", Can. J. Phys. 38, 57(1960) .

11. J.E. Suich and H.C. Honeck, "The HAMMER System - Hetero-geneous Analysis by Multigroup Methods of Exponentialsand Reactors", USAEC Report DP-1064 (1967).

12. R.E. Kay and R.E. Green, "CANDU Booster Rod Experimentin ZED-2", AECL-2525 (1965).

* AECL-XXX: Published report by Atomic Energy of Canada Ltd,

TABLE A-l

DETECTOR PARAMETERS(a)

FoilType

Cu

Cu

Cu Strip

Au

Au Strip

1% Au-Al

10% Lu-Al

5% Mn-10%Lu-Al

1% In-Al

Diameter(cm)

0.775

1.422

0.5 cmwide

1.422

0.5 cmwide

0.775 &1.422

0.775 &1.422

1.422

1.422

Foil Thicknessmg/cm2

(cm)

114(0.013)

114(0.013-)

114(0.013)

24.6(0.0013)

24.6(0.0013)

69(0.025)

39(0.013)

72(0.025)

35.5(0.013)

ActivityDetected

Cu6*

Cu61*

Cu61t

A u 1 9 8

Au 1 9 B

Au 1 9 8

Lu 1 7 7

Mn 5 6

Lu 1 7 7

In1I6ra

Westcott Parameters

g

1.000

1.000

1.000

1.006

1.006

1.006

(b)

1.000(b)

1.023

So

17.50

17.50

17.50

(b)

0.735(b)

18.80

Self Shielding Factors

Gt

0.997

0.992

0.993

0.979

0.979

0.999

0.995

0.9870.987

0.997

Gr

0.483(d)

0.483(d)

0.969

0.992(c)

0.960( .0.991KC>

0.952

Gr So

0.613

0.613

0.613

8.45

8.45

16.96

17.90

(a) Determined by S.L. Mehta.

(b) Parameters vary with neutron energy.

(c) Calculated for values of 0.143 eV resonance only.

(d) Preliminary value; detector normalizations yielded 0.524 which was used in allcalculations in this report.

K•3(D•1rt

srOMla

srt-no

s?ft

8rt

8o

to

ui

- 58 -

APPENDIX B

Macroscopic Neutron Spectrum Results :

61-element Boosters Parallel to Reference Fuel Assemblies

TABLE B- l

MACROSCOPIC MEASURED NEUTRON SPECTRUM PARAMETERS

CASE 2 8 - 1 0 : 2 8 . 5 8 cm (D20) Reference L a t t i c e

Core Location

K1W

J2W

LOI4E

KL2W

KL2H

H6E

Thermal Pit-KL12W

In/Mn

(a)

Act. Ratio

1.423 +

1.390 +

1.380 +

1.369 +

1.440 +

1.416 +

1.132 +

.014

.014

.014

.014

.014

.014

.011

1.000

0

00

0

00

0

0

n

.026

.024

.023

.022

.026

.025

.008

.184

°+

+

+

+

++

+

X

(b)

.001

.001

.001

.001

.001

.001

.001

ID"3

Lu/MnAct.

1.056

1.051

1.049

1.040

1.069

1.059

1.022

1

(a)

Ratio

+ .

+ .

+ .

+ .

+ ,

+ .

+ .

.000

011

011010

010

011

011

010

r

0.025

0.023

0.022

0.022

0.026

0.024

0.008

T

(°c

35

34

3331

39

36

26

:)

++

++

+

+

+

3

3

33

3

3

3

21.01

Method

(c)

(a) The reported activity ratios are ratios at the measurementposition, relative to the same ratio at the thermal pitlocation. The r/T /T value reported at the thermal pitwas determined from a Cd ratio method with In foils.

(b) To = T D 2 1 > 0 1

(c) 1.422 cia d iameter Lu-Mn-Al and In-Al f o i l package .

59 -

TABLE B-2

MACROSCOPIC MEASURED NEUTRON SPECTRUM PARAMETERS

CASE 28-20: 28.58 cm (DjO) Reference Lattice

61-element 20* 235U Booster at KO

Core Location

K1WJ2W

L0

I4EKL6W

JK3W (W)Cal. Surface

H6E

Thermal Pit-KL12W

Au/Cu or (a)

In/MnAct. Ratio

1.

1.

1.

1.

1.

1.

1.

1.

1.

1.1.

1.

1.

1.

1.1.

1.

688 +

370 +

404 +

378 +

435 +

445 +

462 +

406 +

424 +

428 +

224 +

523 +

558 +

524 +

544 +

244 +

128 +

.022

.018

.019

.018

.019

.019

.019

.019

.014

.014

.012

.020

.021

.014

.015

.012

.015

1.000

W

0.

0.

0.

0.

0.0.

0.

0.

0.0.

0.

0.

0.0.

0.

0.

0

0

045

024

026

025028

029030

027

028026

031

034

036034

033

034

009

950

o

i -"o1

+ .001

+ .001

+ .001

+ .001

+ .001

+ .001

+ .001

+ .001

+ .001

+ .002

+ .001

+ .001

+ .001

+ .001

+ .002

+ .001

x 10~3

Lu/Cu or (a>

Lu/MnAct. Ratio

1.085 +

1.048 +

1.063 +

1.044 +

1.061 +

1.053 +

1.072 +

1.046 +

1.059 +

1.046 +

1.109 +

1.122 +

1.131 +

1.085 +

1.032 +

.014

.014

.014

.014

.014

.014

.014

.014

.011

.001

.015

.015

.011

.011

.014

1.000

0

0

0

0

00

00

00

0

0

00

0

r

.043

.024

.026

.024

.028

.028

.029

.029

.027

.025

.033

.034

.022

.032

.009

Tn

- 60 -

TABLE B-3

MACROSCOPIC MEASURED NEUTROH SPECTRUM PARAMETERS

CASE 28-30: 28.58 cm (D2O)Reference Lattice61-element 93% 2 S 5u Booster at K0

Core Location

K1W

J2W

I4E

K4W

JK2W

H6E

Thermal Pit- KL12W

Au/Cu or (a)In/Mn

Act. Ratio

1.626 +

1.332 +

1.329 +

1.351 +

1.383 +

1.416 i

1.429 +

1.435 +

. 1.100 +

.022

.011*.

.018

.014

.014

.014

.014

.014

.015

1.000

r

0

0

0

0

0

0

0

0

0

0

.041

.022

.022

.023

.023

.027

.028

.026

.007

.127

+

+

+

+

+

+

+

+

+

X

(b)

.001

.001

.001

.001

.001

.001

.001

.001

.001

ID"3

Lu/Cu or (a)Lu/Mn

Act. Ratio

1.047 + .010

1.052 + .011

1.063

Documents

PART !: NEUTRON SPECTRUM PARAMETER iEASURE^ENTS · Relative gold-copper, lutetium-copper, or indium-manganese, lutetium-manganese activity ratios were determined in the perturbed