Author(s): Madison Sellers, Tim Goorley Los Alamos ... · Emily Corcoran, Davbid Kelley, RMC. MCNP6...

Post on 27-Jul-2020

2 views 0 download

Transcript of Author(s): Madison Sellers, Tim Goorley Los Alamos ... · Emily Corcoran, Davbid Kelley, RMC. MCNP6...

Form 836 (7/06)

LA-UR- Approved for public release; distribution is unlimited.

Los Alamos National Laboratory, an affirmative action/equal opportunity employer, is operated by the Los Alamos National Security, LLC for the National Nuclear Security Administration of the U.S. Department of Energy under contract DE-AC52-06NA25396. By acceptance of this article, the publisher recognizes that the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or to allow others to do so, for U.S. Government purposes. Los Alamos National Laboratory requests that the publisher identify this article as work performed under the auspices of the U.S. Department of Energy. Los Alamos National Laboratory strongly supports academic freedom and a researcher’s right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness.

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