45 10. HENRIE, J.O. Properties of Nuclear Shielding ...978-94-009-5632-2/1.pdf · 10. HENRIE, J.O. Properties of Nuclear Shielding Concrete. Journal of the American Concrete Institute

45

10. HENRIE, J.O. Properties of Nuclear Shielding Concrete. Journal of the American Concrete Institute. July 1959.

11. ITO, N. and YANAGAWA, A. Method for Manufacturing High Boron Concrete for Radiation Protection. Japanese Patent No. 43-11793, May 1983.

12. BS 4975 : 1973, Specification for Prestressed Concrete Pressure Vessels for Nuclear Reactors, British Standards Institution.

13. GREGORY, A.R. CEGB Proof of Evidence on Decommissioning. Sizewell 'B' Power Station Public Enquiry. November 1982.

14. NUREG, CR 0130. Technology, Safety and Costs for Decommissioning of a Reference Pressurised Water Reactor. U.S. Nuclear Regulatory Commission. June 1978.

11. ACKNOWLEDGEMENTS

On behalf of Taylor Woodrow Construction Limited, the authors gratefully acknowledge the financial and technical support afforded to them during the study by the Commission of the European Communities, the Nuclear Installations Inspectorate, the Central Electricity Generating Board, the National Nuclear Corporation Limited and the Department of the Environment. Thanks is also given to the Central Electricity Generating Board for its permission to reproduce figures nos. 1, 2, 3, 4 and 8.

The authors also acknowledge the help given to them by their colleagues in carrying out the work and preparing the report.

12. TABLES AND FIGURES

Table 1

Table 2

Figure 1 2 3 4 5

6

7

8

9

Results of ultimate load analysis of structures having planes of weakness. Comparison of activity levels in PWR for 10 year and 100 year decay times.

Site plan - typical magnox station. Section through typical magnox station. Site plan - typical AGR station. Section through typical AGR station. Section through Hartlepool/Heysham I multicavity reactor vessel. Section through Heysham II/Torness single cavity reactor vessel. Assumed activated zone of a typical AGR prestressed concrete pressure vessel. Variation of average permissible access times inside vessel (with core intact) and dose equivalent rate, with time after shutdown. View on outside face of a typical PCRV liner.

46

10 Section through typical PCRV showing main internal structures and items.

11 Proposed arrangement of planes of weakness in the activated zone of a prestressed concrete pressure vessel.

12 Planes of hollow tubes. 13 Crack inducer slots. 14 Preformed cavities. 15 Alternative liner anchor detail (a). 16 Alternative liner anchor detail (b). 17 Possible detail to facilitate removal of penetration end

attached to main liner. 18 Grouped and debondedpenetrations. 19 Planes of weakness analysis - structure type 1. 20 Planes of weakness analysis - structure type 2. 21 Finite element grid for assessment of structural effects of

planes of weakness. 22 Planes of weakness analysis - location of stress profile

control points. 23 to 25 Typical comparison of D.R. and F.E.

Analyses of structure Type 1. 26 Stress profiles for structures type 1 and 2, Load Case 1,

Profile 6, Vertical. 27 Stress profiles for structures type 1 and 2, Load Case 1,


Profile 2, Radial. 29 Stress profiles for structures type 1 and 2, Load Case 1,


Profile 2, Hoop. 31 Stress profiles for structures type 1 and 2, Load Case 1,







Profile 7, Hoop. 38 In-situ construction formation of planes of weakness within

a normal sized pour. 39 Outline proposal for grouted liner. 40 Proposed detail of junction between grouted main liner and

gas duct. 41 Outline scheme for removal of standpipe region to give

access for removal of reactor core and internals. 42 Site plan - typical PWR station. 43 Major structures of typical PWR station. 44 Reactor building outline of typical PWR station. 45 Reactor building structures of typical PWR station. 46 Nuclear steam supply system of typical PWR. 47 Section through reactor pressure vessel of typical PWR.

47

48 Section through loop pipe penetration of typical PWR pressure vessel.

49 Section through detector slot of typical PWR pressure vessel.

50 Plan showing detector slots of typical PWR pressure vessel.

51 Plan on I.S.I. gallery of typical PWR. 52 Plan on fuelling pool of typical PWR. 53 Section showing possible location for water tanks in PWR

primary shield wall. 54 Plan showing possible location for water tanks in PWR

primary shield wall.

48

TABLE 1

STRUCTURE

Type 1 (No planes of weakness)

Type 2, with all reinforcement outside planes of weakness zone

RESULTS OF ULTIMATE LOAD ANALYSES OF STRUCTURES HAVING PLANES OF WEAKNESS

VESSEL PRESSURE LOAD AT ULTIMATE LOAD FACTOR (p.s.i)

1632 2.534

1624 2.521

Type 2, with haunch 1631 2.533 reinforcement increased by 20%

FAILURE CRITERIA

Longitudinal crack width

Lo ng it ud ina1 crack width

Longitudinal crack width

TABLE 2

COMPONENT

Activated Plant:

reactor internals reactor pressure vessel biological shield

Contaminated Plant:

- in containment:

steam generators primary coolant circuit

COMPARISON OF ACTIVITY LEVELS IN PWR FOR 10 YEAR AND 100 YEAR DECAY TIMES

(Extracted from Ref. 11)

10 YEAR DECAY

MATERIAL MASS TOTAL MEAN (t) ACTIVITY SPECIFIC

(Ci) ACTIVITY (Ci t-1)

stainless steel 210 840000 4000

mild steel 400 1700 4.3 concrete and 600 80 0.13

reinforcement

stainless steel 1250 700 0.56

stainless steel 520 37 0.07

- in other buildings:

auxiliary building steel 145 36 0.25 fuel building steel 12 3 0.25 radwaste building steel 80 25 0.31

Contaminated Structures:

- in containment concrete 1900~ 0.2** 0.0001 - in containment mild steel 670~ 0.6** 0.0009 - in other

buildings concrete 5700~ 0.8** 0.00014 - in other

buildings steel 1100 1.4** 0.0013

Notes:

49

100 YEAR DECAY

TOTAL MEAN ACTI- SPECIFIC VITY ACTIVITY (Ci) (Ci C 1)

110000 520

40 0.1 4 0.01

100 0.08

5 0.009

- -- -- -

0.03** 0.000016 0.08** 0.00012

- -- -

1 * These data refer to the maximum values of the estimated quantity of contaminated concrete surfaces. The minimum quantity may be a factor 50 less.

2 ** These data refer to the maximum values of the estimated activity levels. The minimum levels may be a factor 300 less.

3 No credit is taken in this data for any decontamination operations which may precede decommissioning.

50

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Standpipe Zone

REACTOR CORE

Vertical Presfressin -""""----'

Tendons

Prestressed Concrete Boiler Closure

Boiler ~I-++--~

IHIt---+-----lJ-l--fi;l--~Cor e Sh ield rng

Circulator ~"-+E--~

Wire Wound Hoop Prestressing Tendons

Fig.5. SECTION THROUGH HARTLEPOOLjHEYSHAM 1 MULTICAVITY REACTOR VESSEL

Gas Dcrne

Cere ~ .. l.-Ili.-w-.

Stcndpipe Zale

REACTOR CORE

Fig 6 SECTION THROUGH HEYSHAM HI TORNESS SINGLE CAVITY REACTOR VESSEL

55

56

r---_________ L..., - ~

.................................. .... ...................................................................................... ~\y::::::::::::::::::::::::::::::::::::::::::::::::::::::: ~~

Activated zone ---+ : :w..---up to 1m. thick

..;.:.; I I

.. ,:-1 I .. : .. ....., .......................................................................................................................... .... ................................................................................................................ .... .. .... .......................................... ........ .............. .......................... ...................... .... ..

_ ~~------------._r-~~~~ 1 -4-

Fig 7. ASSUMED ACTIVATED ZONE OF A TYPICAL AG.R. PRESTRESSED CONCRETE PRESSURE VESSEL

---, s::. > ~

E -II -a "--C II -a > :J tr II

II en 0

" a E E a

(!)

1000 Permissible average acces s times

ToP of core

100

Note: Average access times are based on a mean

10 individual exposure of 5 m Sv y.l man - 1 and

a 40 hour wee k.

Gamma dose equivalent 0.1 rate. side of core.

Total 108m Ag

0.01 94 Nb

Contributions from principal isotopes.

0 20 40 60 80 100 120 140 160 180

Time after shutdown (years)

Fig 8. VARIATION OF AVERAGE PERMISSIBLE ACCESS TIMES INSIDE VESSEL (WITH CORE INTACT) AND DOSE EQUIVALENT RATE. WITH TIME

AFTER SHUTDOWN.

57

40 30 20

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58

Circulator netration

I11rtfmtftt+Hm!J-~Rolied angle

Fig9. VIEW ON OUTSIDE FACE OF A TYPICAL PCRV LINER

Sections

rr Boiler-Feed rnd Refu f>e,etrat'ns

Vessel Liner

Man Atxess Penetration

....

r :'1 'I ~ ; I .~

~ . 'T '.' .,

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Fig.10, SECTION THROUGH TYPICAL PCRV SHOWING MAIN INTERNAL STRUCTURES AND ITEMS

59

60

1 ,.....

U

r-- ~

mr ,IT

rHt-III

'I' III

1m; Minimum pathway , , 14 through concrete ,

/1 ~:r1 ( i) -i I I I I I I ~-, • r--~ I ,

V -, I ,

I- , I ~_J

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a Typical end cap block '--

... - - r _ ~ L- -41-. -4-L.. - L-

Fig 11. PROPOSED ARRANGEMENT OF PLANES OF WEAKNESS IN THE ACTIVATED ZONE

OF A PRESTRESSED CONCRETE PRESSURE VESSEL

- ~. -'·4 · .. , .":

Hollow tubes or cooling 'Mlter ---&..:.-: ....

pi pes arranged to form plane of weakness

Fig.12. PLANES OF HOLLOW TUBES

Preformed Slot----......

Stress concentration under - _ -/

tension causes cracking

Rg.13. CRACK INDUCER SLOTS

Preformed hole for insertion of explosive charges or pressure bursters

... ... " . .. .. .. :. "II:"· : : ...

•

.' . " . .. -..,.." . ·:~:~6' .· :

Fig.14. PREFORMED CAVITIES

61

62

Liner

Shouldered nut which can ao~off

., .

•

Liner Anchor

•

Fig.15. ALTERNATIVE LINER ANCHOR DETAIL (a)

Liner

. S'

Drill bit locatcr

•

• • •

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Fig.16. ALTERNATIVE LINER ANCHOR DETAIL (b)

1000

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68

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FIG. 25

DISTANCE 1M)

LORD CRSE 2 PRESTRESS + PROOF PRESSURE

PROFILE 7

HOOP STRESS

PLANES OF WEAKNESS ANALYSIS TYPICAL COMPARISON OF D.R. AND F.E. ANALYSES OF STRUCTURE TYPE 1

~ MIff'" Of m'El

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LOAD CASE 2 PRESTRESS + PROOF PRESSURE

PROFILE 2 RADIAL STRESS

FIG. 24 PLANES OF WEAlOOlSS ANALYSIS

+ + D. R. AXISTMMETRIC

__ f.E. AXISTMMETRIC

TYPICAL COMPARISON OF D.R. AND F.E. ANALYSES OF STRUCTURE TYPE 1

67

64

Penetrat ions cast in amulusnot fully bonded to rest of structure

.... --- --- .... ,- ~ ..... ", " /' ,

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................... ...,/

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Fig.18. GROUPED AND DEBONDED PENETRATIONS

Fig.19. PLANES OF WEAKNESS ANALYSIS

STRUCTURE TYPE 1

Fig. 21. FINITE ELEMENT GRID FOR

ASSESSMENT OF STRUCTURAL EFFECTS OF PLANES OF WEAKNESS

Fig.20. PLANES OF WEAKNESS ANALYSIS

STRUCTURE TYPE. 2

.L 1 PrO"le~

1 ] Pro~

I 1 I T

I

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I

1 I

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PLANES OF WEAKNESS ANALYSIS LOCATION OF STRESS PROFILE

CON TROL POINTS

65

70

co

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FIG. 27

DISTRNCE IMI

LOAD CASE 1 PRESTRESS ONLY

PROFILE 7 VERTICRL STRESS

PLANES OF WEAKNESS ANALYSIS TYPICAL COMPARISON OF STRESS PROFILES FOR STRUCTURES TYPE 1 AND 2

r-- IOn .. or ""El

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FIG. 26

DISTRNCE IHI


PROFILE 6 VERTICRL STRESS


69

+

+ + STRUCTURE 1

__ STRUCTURE 2

0.0

r-- IOn .. '" """

66

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FIG. 23

LOAD CASE 2 PRESTRESS • PROOF PRESSURE

PROFILE II VERTICAL STRESS

PLANES OF WEA.KN]5S ANALYSIS

+ + D.R. AXISTMMETRIC

__ F.E. RXISYMMETRIC

TYPICAL COMPARISON OF D.R. AND F.E. ANALYSES OF STRUCTURE TYPE 1

~

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o

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1 o

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+

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FIG. 28

o ISTRNCE IHI

LOAD CASE I PRESTRESS ONLY

PROFILE 2

RADIAL STRESS

~ co,,", IF """

PLANES OF WEAKN:HSS ANALYSIS TYPICAL COMPARISON OF STRESS PROFILES FOR STRUCTURES TYPE 1 AND 2

71

72

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<>

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TI' OF 'ES'" --1

FIG. 29

OISTRNCE IHI


PROFILE 7 RRDIRL STRESS

PLANES OF WEAKNESS ANALYSIS TYPICAL COMPARISON OF STRESS PROFILES FOR STRUCTURES TYPE 1 :AND 2

r--- IOn .. or mSEl

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co

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co o co

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__ STRUCTURE 2

7 Iq.o 12,0 10,0 B.O 6.0 q.o 2.0 0.0

fD"Of""" ~

FIG. 30

DISTRNCE IMI

LOAD CASE I PRESTRESS ONLY

PROFILE 2 HOOP STRESS

~"""Df""'l.

PLANm OF WEAKNESS ANALYSIS TYPICAL COMPARISON OF STRESS PROFILES FOR STRUCTURES TYPE 1 AND 2

73

74

co

2 co

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co .,;

co

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FIG. 31

+ + + + +

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DISTRNCE 1"1

LORD CRSE I PRESTRESS ONLY

PROFILE 7

HOOP STRESS


+ + STRUCTURE I

-- STRUCTURE 2

2.0 0.0

~ .rl1llO OF """

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.,

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.,

.;

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<>

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IOI'Of""fL~

FIG. 32

OJ STRNCE IMI

LOAO CASE 2 PRESTRESS + PROOF PRESSURE

PROFILE 6

VERTICRL STRESS


75

+ + STRUCTURE 1

-- STRUCTURE 2

2.0 0.0

r-- 10"l1li Of JUSlL

76

C>

.,;

C>

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C>

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N

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FIG. 33

DISTRNCE (HI

LOAO CASE 2 PRESTRESS • PROOF PRESSURE

PROFILE 7 VERTICAL STRESS


r--- IOn .. or ,mEl

'" ...

'" on

'" '"

'" c '" ,

'" '" , o

=f o

<? o

of '" 'i '" ; '" .... o

+

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EDKorntsEL --I OISTANCE tN) r-- CO'IE ,., nSSEl

FIG. 34




77

+ + STIlUCTURE 1

-- STRUCTURE 2

78

<> eft

<>

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<> .,;

<>

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<> nO

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<>

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<> ., <> m

+

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FIG. 35

DIsrANCf IMI



PLANES OF ~S ANALYSIS TYPICAL COMPARISON OF STRE:)S PROFILES FOR STRUCTURE5 TYPE 1 AND 2

+ + STRUCrURE I

__ STRUCrURE 2

., ..

.,

...

., '" ., N

., o ., 7

'" N , ., ~ ., of ., u? ., <f ., ~ , ., m , ., '" , ., .,

+ +

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EO" Of "'>EL --1 DISTANCE {M} ~ '''''' Of ""a


PROFILE 2

HOOP STRESS

FIG. 36 PLANES OF WEAKNESS ANALYSIS

+ + STRUCTURE I

__ STRUCTURE 2

TYPICAL COMPARISON OF STRESS PROFILES FOR STRUCTURES TYPE 1 AND 2

79

80

c

~ .. '" c .; c .... .. <D .. .; .. ,;. .. '" .. .. .. .. c

, .. '" c

'" , .. ~ , .. "' , .. <D , C

.... , c

1 .. ~ .. o

+

+ + +

+ + STRUCTURE 1

__ STRUCTURE 2

'30.0 le.O 26.0 2~.0 21.0 20.0 le.o 16.0 I~.O 12.0 10.n e.o 6.0 ~.O 2.U 0.0

TIP '" "55EL --1

FIG. 37

·0 [STANCE IMI


PROFILE 7

HOOP STRESS


I-- "'TT'III OF ,mEL

81

Shuttered face

\ Planes of Weakness

Formers

Previous Pour Previous Pour

tinuous In-situ Ccn:rete '--'---

Fig.38. IN-SITU CONSTRUCTION FORMATION OF PLANES OF WEAKNESS WITHIN

A NORMAL SIZED POUR

82

Fig.39. OUTLINE PROPOSAL FOR GROUTED LINER

II' • .: 'II •

••

...•. · ~ ,'.'

I

.~.:: . ....

. " .. • III ' ~ • ~ .... ..

83

...---Grout

........--Main Liner

.'

.' ----Seal Welds L :.

.. '.

. . . .. ',., I' ...... :: • ..... / '::: ... :.::::::::'.:::'

. •.. p' .P"If""'I('~~~ . ' .".

"--------- Gas Duct or other penetration

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AND GAS DUCT

84

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85

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89

90

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Fig 48 SECTION THROUGH LOOP PIPE PENETRATION OF TYPICAL PWR PRESSURE VESSEL

91

92

, Cover plate ------------, , Reactor cavity seal ring ----------,

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98

APPENDIX A

SUPPLEMENTARY INFORMATION

This appendix contains additional infonnation and discussion relating to a number of ideas mentioned but not fully described in the main report.

(a) Provision of preformed holes for the placement of explosive charges.

The use of explosives for the controlled demolition of concrete biological shields and pressure vessels is being investigated by !WC under Project 3 of the CEC programme on nuclear plant decommissioning. n"is work has shown that small explosive charges placed in holes formed at right angles to the inside face of a massive concrete structure can be used to strip off concrete layers from the face. Each concrete layer stripping operation is carried out using predetermined charge spacing and depth of burial designed to give optimum results with respect to safety, volume of material excava.ted and econ011lY. The layer by layer stripping operation is continued until the required thickness of concrete has been cratered off, or excavated. The indications are that a one metre thlckness could be fa.irly satisfactorily removed in a series of four layer stripping operations. If a mat of reinforcement is present close to the face of the concrete, the effect of the fit'st layer round of firings will be to blow the cover off and, depending on the reinforcement detail, break up some concrete behind the reinforcement. The reinforcement mat so exposed can be cropped or cut away to release any debris held behind it. Once the reinforcement mat has been removed the stripping process proceeds as normal.

No tests have been carried out to assess the effect of a liner bonded to the concrete by studs. It may be that, if the liner is cut through into discrete plates consistent with the expected pattern of explosive cratering, the concrete can be blown off in discrete pieces with the liner still attached to it. n"is would, however, have to be investigated by a programme of testine.

The layout of boreholes required to strip a given thickness, say one metre, of concrete could be predetermined at the design stage. This being so it would be possible to form holes in the concrete during construction of the vessel subject to the maintenance of adequate shielding. n"is would permit the placement of charges during decommissioning without having to bore or cut holes first. Boring or cutting such holes would produce a cert~ln amount of activated waste Which would have to be suitably disposed of. It would also be a time consuming process, increasing radiation doses received by decommissioning workers. A preferable approach would be to use shaped charges Which are faster and produce negligible active waste.

There are, however, two main problems with preformed holes:-

(1) Shine paths for radiation. (2) Integrity of the liner.

99

The concentration of holes will be such that shine paths for radiation could be a problem, forming 'hot spots' of activation outside of the designated activated zone. If unacceptable, this could be overcome if the holes were plugged with a material with good neutron Rhielding properties. Assuming that the concrete is cast up against the liner, the hole filler would have to be a solid object, such as graphite or lead, fixed in position before concrete placing, suitably debonded from the concrete. The size of the holes would be limited by the ability of the liner to span the hole, and whether the material in the hole could support the liner. In carrying out the ultimate load analysis for the Hartlepool/Heysham I vessels, crack width was limited to 32mm for this reason. It is not thought likely that the density of holes would cause major problems due to stress concentrations but this would have to be checked following design of a suitable layout of charges.

(b) Provision of preformed holes for the placement of a chemical demolition agent.

The use of a non-explosive chemical demolition agent to split up concrete overcomes problems due to noise, vibration, dust, flying debris, etc. associated with the use of explosives. If mixed with water and poured into cylindrical holes formed in the concrete, "BRISTAR" expands, generating eracks in the surrounding concrete. Thls product has been successfully used for breaking up rock and massive unreinforced concrete structures. For reinforced concrete, a close hole spacing of about 200mm to 300mm is requlred, hole diameters being 40mm to 5Omm. Provision of preformed holes subject to provisos mentioned in item (a) above ~ould aid the use of such an agent, but the number of holes would be such that stress concentrations could become quite significant.

(c) Provision of preformed cavities for the insertion of mechanical burster.

There are two types of hydraulic burster, namely wedge type and piston type, anrl both split the concrete by expanding outwards against the circumference of a suitable hole into which they have been placed. The spacing of holes, their posi tion, depth and angle govern the success of bursting. Generally speaking, the hole for the insertion of the burster should be less than 500mm from a free face. Alternatively, a number of bursters can be used simultaneously, in holes about 600mm apart in a line about 600mm from the free face. Hole diameter depends on the type of burster being used. Provided a free working face could first be established, hydraulic bursters could provide a controlled means of splitting up activated concrete for removal. The provision of preformed holes, subject again to the provisos mentioned in item (a) above would save the time consuning and expensive job of cutting or boring holes.

100

(d) Improvement in the neutron shielding properties of concrete to reduce the volume of activated concrete and surface dose rates.

Activation of the concrete in a PCRV is caused by production of radioactive isotopes due to capture of neutrons by the nucleii of certain elements present in the concrete. Before capture, fast neutrons must be slowed down to thermal levels. Hydrogen is very effective at slowing down neutrons over a wide range of energies. By increasing the amount of hydrogen in concrete, the neutron attenuating properties of the concrete can be improved and two methods of increasing the proportion of hydrogen in hardened concrete are:

(1) Increasing the amount of free and chemically bound water in the hardened cement paste.

(2) Using hydrous aggregates.

Method (1) could involve increasing the fineness of the cement and increasing the cement and water content of the mix combined with stringent curing procedures during construction. Migration of free water through concrete is very slow, even under PCRV operating temperatures. Naturally occurring aggregates with a high hydrogen content include limonite, geophite and serpentine.

The adoption of any of these measures would have to be preceded by trials to establish the effects on workability, heat of hydration during construction, creep and shrinkage properties and long term strength and durability of the resulting concrete.

Boron is very effective in capturing thermal neutrons and does not produce gamma-emitting isotopes. The addition of boron to concrete will reduce dose rates received by decommissioning workers from harmful gamma radiation. Some of the more readily available boron containing additives are soluble in water and have a deleterious effect on the concrete setting process. As a result, borated concretes used in practice in reactor construction in the U. S.A. and Japan have typically had boron contents of less than 1% by weight. However, Japanese researchers have succeeded in producing concrete mixes wi th a boron content of up to 6.4% using non-soluble boron frits. The presence of these appears to retard slightly the early gain of strength, but 28 day strengths similar to or even greater than comparable mixes without boron are achieved, and all of the trial mixes reported had 28 day strengths of greater than the 40 N/mm2 commonly specified for PCRVs. Incorporation of boron in the PCRV concrete may also affect reactor operating characteristics.

(e) Use of an alternative material to mild steel for the liner.

Discussions with liner design engineers have revealed that alternative materials to steel for liners have been investigated in the past. One of the important properties required by material used on heavy civil engineering construction sites is durability against damage from both normal site operations and misuse of equipment such as dropped scaffold tubes, reinforcing rods and the like. Recent tests on high density polyethylene sheet have shown that this material can be easily penetrated by dropped objects and, although easily repaired, the integrity of

101

the liner would depend on all such damage being identified before the liner is built in or covered up. Plastic materials used in industry for containment liners have good chemical resistance and elasticity properties but are not able to withstand the high temperatures normally found in a reactor. The long term effect of radiation on some plastics, with resulting embrittlement, is also a problem to be taken into account.

Stainless steet is used in nuclear installations as an impermeable containment membrane but this material is normally used where corrosive conditions prevail and Where ease of decontamination is required. Compared with mild steel, stainless steel is considerably more expensive and exhibits a higher level of harmful radioactive isotopes, such as nickel, when subjected to radiation. All enquiries to date have failed to identify a better material than mild steel for the liner.

Documents

45 10. HENRIE, J.O. Properties of Nuclear Shielding ...978-94-009-5632-2/1.pdf · 10. HENRIE, J.O. Properties of Nuclear Shielding Concrete. Journal of the American Concrete Institute