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Title:
Author(s):
Intended for:
11-05868
MCNP6 Delayed Neutron Emission Validation withExperimental Measurements
Madison Sellers, Tim GoorleyLos Alamos National Laboratory
Emily Corcoran, Davbid Kelley, RMC
MCNP6 D l d NMCNP6 Delayed Neutron Emission Validation with
Experimental Measurements
Presented by: Madison Sellers
Supervisors: Dr. Tim Goorley, LANL
Dr. Emily Corcoran, RMCDr. David Kelly, RMC
LA-UR 11-05868
October 11 2011
OverviewOverview
• Introduction, Background & Theory, g y
• Experimentationp
• MCNP6 Model
• Results & Discussion
• Conclusions
2
The Delayed Neutron Counting System
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
The Delayed Neutron Counting System
C d i • Constructed in 2010
• Validated for 235U analysis, aqueous samples
• Current experiments include 233U samples
• Expanding analysis to include 239Pu analysis and mixtures of two or more fi il i t fissile isotopes
• Winter 2011/2012 will be updated with new hardware to increase sensitivity and efficiencyy
3
Delayed Neutron Generation
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
Delayed Neutron Generation
• Many delayed neutron precursors
Group t1/2 [s] λ [s-1] βi = νi/νd [%]
1 55 6 0 014267 0 0328 ± 0 0042 Fissile Isotope1 55.6 0.014267 0.0328 ± 0.0042
2 24.5 0.028292 0.1539 ± 0.0068
3 16.3 0.042524 0.091 ± 0.009 γ
β
ss e sotopePrompt n
Delayed n
4 5.21 0.133042 0.197 ± 0.023
5 2.37 0.292467 0.3308 ± 0.0066
6 1.04 0.666488 0.0906 ± 0.0046
β-
γDelayed neutron Precursor
7 0.424 1.634781 0.0812 ± 0.0016
8 0.198 3.554600 0.0229 ± 0.0095
4
Delayed Neutron Generation
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
Delayed Neutron Generation
• Eight (or 6) groups, denoted by t1/2 and production ratio
109
1010
Group t1/2 [s] λ [s-1] βi = νi/νd [%]
1 55 6 0 014267 0 0328 ± 0 0042
ns /
(cps
)
106
107
1081 55.6 0.014267 0.0328 ± 0.0042
2 24.5 0.028292 0.1539 ± 0.0068
3 16.3 0.042524 0.091 ± 0.009
Neu
tro103
104
105 Group 1Group 2Group 3Group 4Group 5Group 6Group 7
4 5.21 0.133042 0.197 ± 0.023
5 2.37 0.292467 0.3308 ± 0.0066
6 1.04 0.666488 0.0906 ± 0.0046
Time / (s)0 10 20 30 40 50 60
101
102p
Total DN Production7 0.424 1.634781 0.0812 ± 0.0016
8 0.198 3.554600 0.0229 ± 0.0095
5
Delayed Neutron Generation
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
Delayed Neutron Generation
• Production ratios dictated by fission fragment yields
109
1010
Group t1/2 [s] λ [s-1] βi = νi/νd [%]
1 55 6 0 014267 0 0328 ± 0 0042
ns /
(cps
)
106
107
1081 55.6 0.014267 0.0328 ± 0.0042
2 24.5 0.028292 0.1539 ± 0.0068
3 16.3 0.042524 0.091 ± 0.009
Neu
tro103
104
105 Group 1Group 2Group 3Group 4Group 5Group 6Group 7
4 5.21 0.133042 0.197 ± 0.023
5 2.37 0.292467 0.3308 ± 0.0066
6 1.04 0.666488 0.0906 ± 0.0046
Time / (s)0 10 20 30 40 50 60
101
102p
Total DN Production7 0.424 1.634781 0.0812 ± 0.0016
8 0.198 3.554600 0.0229 ± 0.0095
6
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
%)
10
235U233U
βi = νi/νd [%]
0.0328 ± 0.0042Yie
ld /
(%
6
8 233U239Pu
0.0328 0.0042
0.1539 ± 0.0068
0.091 ± 0.009
0 197 ± 0 023Prod
uct Y
40.197 ± 0.023
0.3308 ± 0.0066
0.0906 ± 0.0046
0 0812 ± 0 0016
Fiss
ion
2
0.0812 ± 0.0016
0.0229 ± 0.009580 100 120 140 160
0
7
Fission Product Mass /(amu)
Each fissile isotope has a i t d l d t
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
Uranium - 235Plutonium - 239Uranium - 233
signature delayed neutron count rate curve
ate
(cps
)Co
unt R
a
k
i
tttij
j
jfjAjj
idiirri eeeM
mNtS
1))()(1()(
*
0 10 20 30 40 50 60
8
Time (s)
*Li X, Henkelmann R, Baumgartner F (2004) Nucl Instrum Methods Phys Res B 215:246–251
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
Each fissile isotope has a
Uranium - 235
Each fissile isotope has a signature delayed neutron
count rate curve
cps)
Uranium - 233Plutonium -239
unt R
ate
/ (c
k
i
tttij
j
jfjAjj
idiirri eeeM
mNtS
1
))()(1()(
Cou
Time / (s)
0 20 40 60 80 100
9
The Delayed Neutron Counting SystemIntroduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
Diverter
Neutron Counter
Automatic Loader
Sample DisposalThe sample is irradiated in the SLOWPOKE-2 reactor
10
Sample Preparation
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
Sample Preparation
2.25 ‘’
0.67‘’
11
7
The Delayed Neutron Counting
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
Neutron Counting System Procedure
Diverter
Neutron Counter
Automatic Loader
Sample DisposalThe sample is irradiated in the SLOWPOKE-2 reactor
12
The SLOWPOKE-2 Reactor
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
The SLOWPOKE 2 Reactor
20 kW research reactor enriched to 19.89%
13
Delayed Neutron Counting Arrangement
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
Delayed Neutron Counting Arrangement
3He Detector
Sample Tubing
Paraffin
14
The Delayed Neutron Counting SystemIntroduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
Diverter
Neutron Counter
Automatic Loader
Sample DisposalThe sample is irradiated in the SLOWPOKE-2 reactor
15
Hardware & Software Control
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
Hardware & Software Control
16
The Fissile Analysis Program
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
The Fissile Analysis Program• Imports count excel file:
SLOWPOKE Test Data
11/04/2011 11:47:49 AM
Standard? YES
Sample # Cycle Time Counts Total Counts
1 A 1 015625 1863 793061 A 1.015625 1863 79306
1.546875 1821
2.0625 1759
• Corrects for background, dead time, normalizes to counts per second
2.59375 1691
17
• Outputs fissile (U-235) content in μg
Fissile Analysis Program Output
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
Fissile Analysis Program Output
10000
12000
6.92 g 235U2 13 g 235U
ate
(cps
)
8000
2.13 g ULeast Squares Fit to Theory
Coun
t Ra
4000
6000
8
1
))()(1()(i
tttij
j
fjAjjj
idiirri eeeMN
mtS
2000
18Time (s)
0 10 20 30 40 50 600
MCNP6 Geometry
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
MCNP6 Geometry
MCNP6 Plotter
19Visual Editor
MCNP6 Input Deck Summary
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
MCNP6 Input Deck Summary
• tme = 0 -60e8 sh
• Sample is exposed to defined neutron flux• DN activity builds
• tme = 60e8 180e8 sh
• F8 tallies record delayed neutron activity
20Visual Editor
MS8
Slide 20
MS8 Describe the INPUT DECKMadison, 10/11/2011
3He Detectors & System Efficiency
Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
He Detectors & System Efficiency
• F8 tallies (pulses) in active zone f d t tof detector
• User-defined delayed neutron energies and temporal behaviour g pusing 8-group model
8
))()(1()( tttfjAj idiirriN
tS
• Experimental Efficiency: 34 ± 5%
1
))()(1()(i
tttij
j
fjjjj
idiirri eeeM
mtS
• MCNP6 Efficiency: 37%
21
Detector Wall Effects –Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
Experimental Measurementsnn
el
E = 0 573 MeV
ETotal = 0.764 MeVaγ background
ts P
er C
han EP = 0.573 MeV
EH 3 = 0.191 MeV
tive
Coun
t EH-3 0.191 MeV
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Relat
En r D p iti n in 3H D t t r (M V)
22
Energy Deposition in 3He Detector (MeV)
Detector Wall EffectsIntroduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
10
Results have
1
nts
Recombination Effects
Results have been scaled
elat
ive
Cou
n
0.1
Re
Experimental WaveformMCNP6 with GEBPhoton Peak at 54 ngPh P k 534
0.010 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Photon Peak at 534 ng
23
Energy (MeV)
S(α,β) for Paraffin & Aqueous Solution Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
( ) q
1.00E-03
1.20E-03
8.00E-04
1.00E 03
nse
(s-1
) Without Thermal Tables
With Thermal Tables
4.00E-04
6.00E-04
ctor
Res
pon
2.00E-04
Det
ec
0.00E+006.00E+09 8.00E+09 1.00E+10 1.20E+10
Time (sh)
2424
Molecular binding and crystalline effects are important at low neutron energies
Neutron Flux Estimate in SLOWPOKE-2Introduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
1E+12
1E+10
1E+11
m-2
s-1)
1E+9
1E+10
Flux
(cm
1E+81E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 1E-2 1E-1 1E+0 1E+1
• 69 Group Energy Spectrum from K. Khattab, I. Sulieman, (2010, Syrian MNSR)
Neutron Energy (MeV)
25
9 p gy p b, , ( , y )
• Magnitude of flux determined experimentally in DNC irradiation site
Neutron Flux & DN BehaviorIntroduction Experimental MCNP6 Model of DNC System Results & Discussion Conclusions
7,000
5,000
6,00069 Group Energy Spectrum
Thermal Neutrons Only
3,000
4,000
ntR
ate
(s-1)
y
1,000
2,000Cou
n
00 10 20 30 40 50 60
C Ti ( )
26
Count Time (s)
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
Each fissile isotope has a
Uranium - 235
Each fissile isotope has a signature delayed neutron
count rate curve
cps)
Uranium - 233Plutonium -239
unt R
ate
/ (c
k
i
tttij
j
jfjAjj
idiirri eeeM
mNtS
1
))()(1()(
Cou
Time / (s)
0 20 40 60 80 100
27
Temporal DN Behavior
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
Temporal DN Behavior
0.50
e (s
-1)
U233 MCNP
U235 MCNP
Cou
nt
Rat
e
PU239 MCNP
Rel
ativ
e
0.050 10 20 30 40 50 60
28
0 10 20 30 40 50 60
Count Time (s)
Experimental Measurements & MCNP6
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
p
0.9
1
0.7
0.8
e (s
-1)
U235 Experimental
U233 Experimental
U233 MCNP
0.5
0.6
Cou
nt
Rat
e
U235 MCNP
0.2
0.3
0.4
Rel
ativ
e
0
0.1
0 10 20 30 40 50 60
29
3 4 5
Count Time (s)
Irradiation DurationIntroduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
0 9
1
0.7
0.8
0.9
5s Irradiation60s IrradiationMCNP6 5s
0.5
0.6
nt
Rat
e (s
-1) MCNP6 5s
MCNP6 60s Irradiation20s Irradiation20s MCNP6
0.3
0.4
elat
ive
Cou
n
0
0.1
0.2Re
30
00 10 20 30 40 50 60
Time Following Irradiation (s)
CINDER vs. ACE Model
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
CINDER vs. ACE Model
MCNP6 Initial Release Notes:
PHYS:N EMAX EMCNF IUNR DNB unused* FISNU COILF CUTN
DNB =delayed neutron control-1001 Analog delayed neutrons from ACE tables (if available, otherwise from CINDER tables))-101 Analog delayed neutrons from CINDER only–1 Analog delayed neutrons from ACE tables only0 No delayed neutrons produced1 15 biased number of neutrons produced per fission1-15 biased number of neutrons produced per fission.101-115 Biased number of delayed neutrons from CINDER tables1001-1015 Biased number of delayed neutrons from ACE tables, otherwise from CINDER tables
31
CINDER vs. ACE Model
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
CINDER vs. ACE Model
MCNP6 Initial Release Notes:
PHYS:N EMAX EMCNF IUNR DNB unused* FISNU COILF CUTN
ACE CINDER JEFF [*]
-1001 -101
ACE CINDER JEFF [*]
Prompt n 11992 11990
Delayed n 60 96
Weight Prompt n 1.52e-5 1.52e-5 1.58e-5
Weight Delayed n 7.61e-8 1.22e-7 1.06e-7
32
Un-normalized Comparisons – 235U (±1σ)Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
4,000
3,000
3,500
)
Experimental Measurement
MCNP6 Cinder
ACE DN Production Ratios
2,000
2,500
oun
t R
ate
(s-1)
1,000
1,500
Co
0
500
5 15 25 35 45 55 65
33
5 15 25 35 45 55 65Elapsed Time Since Irradiation(s)
Future Work
Introduction Background & Theory Experimental Results & Discussion Conclusions & Future Work
Future Work
i d i i d d li• Continued DNC experimentation and MCNP6 modeling
• Longer Count Times• Plutonium-239 & Uranium-233Plutonium 239 & Uranium 233• Mixtures of multiple fissile isotopes
• Delayed Gamma Emission from Special Nuclear Materials
• System to be built at RMC late 2011/2012• To be modeled in MCNP
• Work to be presented and submitted to ANS Conference in 2012
34
Thank you
35
Un-normalized Comparisons – 235UIntroduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
8,000
6,000
7,000
)
ExperimentalCINDER MCNP6ACE
4,000
5,000
oun
t R
ate
(s-1)
2,000
3,000
Co
0
1,000
36
0 10 20 30 40 50 60Count Time (s)
2.5x109
Supplemental Informationps
)
1 5 109
2.0x109Uranium - 235Plutonium - 239Uranium - 233
Coun
t Rat
e (c
p
1.0x109
1.5x109
Each fissile isotope has a signature delayed
neutron count rate curveC
500.0x106
neutron count rate curve
Time (s)
0 10 20 30 40 50 600.0
Time (s)
k
tttij
jfjAjj
idiirri eeeM
mNtS ))()(1()(
n
jtStS )()( BackgroundtStC )()(
Isotope j Count Rate: n isotopes: Total Count Rate:
37
i
jj
j M 1j 1
ε = system efficiency vj = delayed n production NA = Avogadro’s number σf = fission cross section ϕ neutron flux mj mass of isotope Mj Molar Mass of isotope βi production ratio for group iλi lifetime of group i tirr irradiation time td decay time t count time
238U Fission Contributions
Supplemental Information
U Fission Contributions
U d i/ h l i • Used epi/thermal ratio from Andrews thesis
• Account for flux, delayed ccou t o u , de ayedneutron production, isotopic composition of U samples
• Determined that for natural U < 0.001% of DN recorded are from the fission of 238U
38
238U Fission Contributions
Supplemental Information
U Fission Contributions1600
• Samples contain identical amounts of 235U 1200
1400
• DU sample has ~1.35x the ratio of 238U to 235U
• Appears to have no effect on 600
800
1000
Cou
nt
Rat
e
DU
Nat U
• Appears to have no effect on the magnitude of the count rate curve
200
400
600
00 10 20 30 40 50 60
Time / (s)
39
Fission Fragment Yield & Delayed Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
Neutron PrecursorsFissile Isotope
Prompt n
/ (%
)
8
10
235U233U239Pu
γ
β-
D l d
Prompt n
Delayed n
Prod
uct Y
ield
/
4
6
Pu
γDelayed neutron Precursor
Fiss
ion
P2
4
β-
87Br (t1/2 = 55 s)
87Kr
Fission Product Mass /(amu)
80 100 120 140 1600
β-
88Kr + delayed
40
87Kr (ground state)
delayed neutron
System Reproducibility – Natural Uranium
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
Syste ep oduc b ty Natu a U a u
8Ideal: Slope = 1 0 Y-Intercept = 0 0
t / (
g)
6
7 Set ISet IISet III Set IV Set V
SetSlope
(2σ uncertainty)
Y-Intercept (μg)
(2σ uncertainty)
I 0.98 ± 0.01 0.08 ± 0.04
Ideal: Slope = 1.0 Y Intercept = 0.0
Syst
em O
utpu
t
4
5Set VSet VISet VII Set IIX
I 0.98 ± 0.01 0.08 ± 0.04
II 0.96 ± 0.08 0.1 ± 0.4
III 1.00 ± 0.02 -0.02 ± 0.06
IV 1.0 ± 0.1 0.04 ± 0.06
DN
C S
2
3 V 0.98 ± 0.01 0.08 ± 0.04
VI 0.96 ± 0.08 0.1 ± 0.3
VII 1.00 ± 0.02 0.0 ± 0.1
Actual 235U Mass / (g)
1 2 3 4 5 6 7 81 IIX 0.99 ± 0.01 0.04 ± 0.06
41
System V lid i
SampleActual 235U
Mass (μg)
DNC System 235U
Determination (μg)Relative Error
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
Validation –Depleted U i
1 5.52 ± 0.06 5.3 ± 0.2 -3.45%
2 5.56 ± 0.06 5.3 ± 0.2 -5.35%
3 5.50 ± 0.06 5.3 ± 0.2 -3.01%
Uranium 4 5.56 ± 0.06 5.3 ± 0.2 -4.32%
5 5.53 ± 0.06 5.3 ± 0.2 -4.78%
6 5.62 ± 0.06 5.4 ± 0.2 -4.45%
7 5.59 ± 0.06 5.4 ± 0.2 -4.24%
8 5.53 ± 0.06 5.3 ± 0.2 -4.47%Relative Error
-3.6%
Actual 235U mass
(μg)
Total Solution
Mass (g)
Experimental
Mass (g)
Relative Error
(%)
1.54 ± 0.04 0.290 ± 0.003 1.5 ± 0.1 -3.2
1.54 ± 0.04 0.379 ± 0.003 1.5 ± 0.1 -3.2
1.54 ± 0.04 0.568 ± 0.003 1.5 ± 0.1 -2.6
1.55 ± 0.04 0.660± 0.003 1.6 ± 0.1 -0.6
Error independent of solution nitric
acid solution volume
42
1.53 ± 0.04 0.819 ± 0.003 1.5 ± 0.1 -3.9
1.46 ± 0.04 0.738 ± 0.003 1.5 ± 0.1 -1.4
1.59 ± 0.04 0.943 ± 0.003 1.5 ± 0.1 -3.8
Determining 235U Content
Introduction Background & Theory Experimental Results & Discussion Conclusions & Recommendations
ete g U Co te t10
Ideal DNC System OutputDU 5 4 ppm 235U
ut /
( g) 1
DU 5.4 ppm UDU 0.054 ppm 235UNat U 0.073 ppm 235UNat U 7.3 ppm 235U (calibration)
stem
Out
pu
0.1
DN
C Sy
s
0.01
0 001 0 01 0 1 1 100.001
43Actual 235U Content / (g)
0.001 0.01 0.1 1 10