nuclear data evaluation challenges€¦ · evaluation methodology challenges 22 p(nd) 2 -2: 2 nd...

1 P(ND)2-2: 2nd International Workshop on Perspectives on Nuclear Data for

the Next Decade, 14-17 October 2014, Bruyères-le-Châtel, FRANCE

Roberto Capote, IAEA Nuclear Data Section

e-mail: [email protected]

Web: http://www-nds.iaea.org

Nuclear data evaluation challenges

Roberto Capote

IAEA Nuclear Data Section, Vienna, Austria

mailto:[email protected]

http://www-nds.iaea.org/








Thanks to: Organizers for the invitation

IAEA projects’ participants

Collaborators

o A. Trkov (IAEA)

o D.L. Smith (ANL, USA)

o D. Neudecker (LANL, USA)

o E. Soukhovitskii (JIENR, Belarus)

o J.M. Quesada (Univ. Sevilla, Spain)

o S. Chiba (Tokyo Inst. Technology, Japan) OM

P

P

FN

S










Introduction

235U(nth,f) PFNS non-model evaluation

PFNS model evaluation challenges

Reaction modelling challenges

Evaluation methodology challenges

Challenges in use of integral data

Lessons learned on EXFOR compilation

Summary

OUTLOOK










IAEA contributions:

Neutron standards project

Actinide PFNS Coordinated Research Project

Technical work for actinide evaluations

e.g. OMP developments, 238U evaluation

Collaboration with BNL on 56Fe evaluation










PFNS evaluation

challenges










235U(nth,f) PFNS GANDR evaluation

Kornilov et al. (IRMM) data taken as reference

All data converted to 252Cf/235U or

235U/Mxw(1.32MeV) ratios

Upper energy cut-off 10 MeV

252Cf/235U or 235U/Mxw(1.32MeV) ratios integrated

over the overlapping interval for each experiment

Measured data normalised to match integrals over the

overlapping regions (data taken as shape data)

GANDR (GLSQ fit) with almost uninformative prior

Model independent evaluation (Neutron STD)










PF

NS

2

35U

(n,f

) /

Maxw

(T=

1.3

2 M

eV)

non-model evaluation for STD (GANDR)

Eaver(GANDR)= 2.000(9)

Eaver(B/VII.1) = 2.03











0.8% uncertainty

GANDR evaluation: uncertainty analysis

Non-model fit

)()( Y










Challenges of PFNS model evaluation (I)

KALMAN (GLSQ) fit

Uncertainty increased

at 2 MeV

from 0.2% to ~2%!

Outgoing neutron energy [MeV]

M. Rising, P. Talou, T. Kawano, A.K. Prinja et al., NSE 175 (2013) 81

Model too rigid !!

Too few parameters

model fit

)()( Y










25

2C

f(sf

)/2

35U

(n,f

)

Energy [MeV]


new expers

unlikely










0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 150.9

1.2

1.5

1.8

2.1

2.4

2.7

3.0

Kobayashi 92

Mannhart

Kobayashi 80

Zolotarev

TRS 273 (Mannhart)

ENDF/B-VII.1

Trkov et al. CW2014

SP

A c

ross

-se

ctio

n R

AT

IO 2

52C

f(sf

)/2

35U

(nth,f

)

Effective energy E50% (MeV)

PFNS validation using dosimetry data

new expers.

needed !!










0.01 0.1 1 10

2.37

2.38

2.39

2.40

2.41

2.42

2.43

2.44

2.45

2.46

1st E

res

(0.27 eV)

p~0.3%

-1.0%

-1.6%

Gwin 84, set 1

Gwin 84, set 2

Gwin 84, set 3

Reed 72

Simon 73 (unc supressed)

Gwin 84, average, 3 sets

Divadeenam 82

(EVAL micr. = 2.4225)

Axton 86

(EVAL micr. = 2.4261)

ENDF-B/VII.1 (2.4208)

JEFF-3.2 (2.4199)

JENDL-4.0 (2.4205)

p

235

U(nth

,f)]

E[eV]

p

252

Cf(sf)] = 3.760

t=

p+

del

t

252

Cf(sf)]=3.7676

del

252

Cf(sf)]=0.008

thermal

point

+1.0%

235U nubar fluctuations

new expers.

needed !!










Reaction modelling

challenges










Reaction modelling challenges: (n,inl)

R. C., M. Sin, A. Trkov, M. W. Herman, D. Bernard, G. Noguere, A. Daskalakis, and Y. Danon.

NEMEA-7 proceedings, NEA SG-40 (2014) “Evaluation of neutron induced reactions on 238U nucleus”










0.1 1

500

1000

1500

2000

2500

3000 dir-CN interference

elastic

1st level (44.9)

2nd

level (148)

no interference

elastic

1st level (44.9)

2nd

level (148)

cro

ss s

ection

s [

mb

]

energy [MeV]

new physics: DIR-CN interference

Engelbrecht-Weidenmuller

transformation [1]

[1] C.A. Engelbrecht, H.A. Weidenmuller, “Hauser--Feshbach theory and Ericson fluctuations

in the presence of direct reactions”, Phys.Rev. C8 (1974) 859-862

(n,n1)

(n,el)

See Kawano talk

R. C., A. Trkov, M. Sin, M. Herman, A. Daskalakis, Y. Danon, Nucl. Data Sheets 118 (2014) 26-31

“Physics of Neutron Interactions with 238U: New Developments and Challenges”










Kerveno et al, PRC87(2013) 024609 Bacquias/Kerveno et al (prelim., unpublished)

238U(n,n’ )

235U(n,n’ ) 5/2+-7/2 – (gsb)

3- - 2+ (gsb)

129.3 keV

Reaction modelling challenges: (n,n’)

Better structure models => CC OMP

See Kerveno talk










Rigid rotor with soft-rotor (vibr.) corrections

U-238 (similar for 232Th)

Yu.V.Porodzinkij and E. Soukhovitdkii, Phys. At. Nuclei 59 (1996) 228-237

0.0 44.9 149.6

314.2 538.6

1166.9

(+8.4%)

822.8

(+6.0%)

~J(J+1)

rigid

non-axial

octupole

OMP with multiple band coupling gsb










Rigid rotor with soft-rotor corrections

Odd nuclei: multiple-band coupling

7/2-, gsb 5/2+ 1/2+

13.

5/2+

7/2- - 21/2-

1/2 + - 13/2 + 5/2 + - 11/2 +

5/2 + - 7/2 +

235U; 4 coupled bands, 21 coupled levels

DOMP = 238U, different coupling scheme

isomer

(similar for 239Pu, 233U)










Evaluation

methodology

challenges










Unified Monte Carlo

1) MC modeling (EMPIRE, TALYS, CCONE, CoH,…) {σi}

2) For each random set {σi} we calculate L(yE,VE | σi)

L(yE,VE | σi) = exp{-(½)[(f (σi)–yE)T •( VE)-1 • (f (σi)–yE)]}

OUTPUT: 1)

2) Stochastic set {σi} (e.g. to be used in TMC)

jijiN

i

i

N

iii

w

w

),cov(,

)(

)(

1

exp

1

exp

)(exp

iw

jiji

),cov(,

UMC-B

Evaluation Methodology Challenges










Alternatives to GLSQ evaluation: MC methods: No covariance generation needed UMC-B : Solution is obtained as a linear combination of model results However: The solution may not be reproducible by model calculations (additional information is derived from experimental data allowing to overcome potential model defects)

Evaluation Methodology Challenges

See e.g. Koning talk

Go beyond model calculations !










Challenges in using

integral data











Cross-correlations among “reactions”: Elastic vs Inelastic (CS&DA) vs PFNS in fast assemblies -bar vs PFNS in thermal solutions Cross-correlations among isotopes: Big Ten, Flattop-25, Jemima fast critical assemblies 235U (, PFNS, fission, capture) vs 238U (capture, elastic and inelastic) Thermal solutions 235U, 233U, 239Pu (, PFNS, fission, capture) vs 16O & H (elastic)










Lessons learned on

EXFOR compilation










Check EXFOR

PFNS @ En=500 keV, ANL experiment Measured: PFNS ratios 252Cf/233,235U; 252Cf/239,240Pu from 0.6-7 MeV

Fully determines the PFNS average energy <E>

Authors never provided the data, only the <E> shift (model dep.) !!

Excellent experiment !

… but not compiled










PFNS evaluation challenges:

New methodology and PFNS models, uncertainty analysis

Reaction modelling challenges:

Use better structure in reaction calculations (e.g. CC OMPs)

Evaluation methodology challenges

Going beyond model calculations (e.g. UMC-B+TMC)


Cross-isotope and cross-”reaction” correlations

EXFOR compilation challenges

Authors should provide measured (model indep.) quantities

(e.g. capture yields not RP, PFNS ratio not the <E> shift)

SUMMARY





nuclear data evaluation challenges€¦ · evaluation methodology challenges 22 p(nd) 2 -2: 2 nd...

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