NUDUNA: “Nuclear Data Uncertainty Analysis”

Oliver Buss, Axel Hoefer, Jens-Christian NeuberAREVA GmbH, PEPA-G (Offenbach, Germany)

Meeting on uncertainty propagations in the nuclear fuel cycle Uppsala University, April 24-25, 2013

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ContentMotivation Nuclear data uncertainty impact and criticality safety

Methods for estimating the impact of Nuclear Data Uncertainty

Monte-Carlo approach to the propagation of Nuclear Data uncertainty

NUDUNA framework Present issues with available uncertainty information Results for keff and depletion

Summary & Outlook

Motivation

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MotivationCriticality safety evaluations for (re-) processing, storage, transport and final disposal of nuclear fuel Small Margins additional to the Regulatory Safety Margin Regulatory Safety Margin: keff<0.95, 0.98 or even keff<1.00

Analyses rely on transport codesDifferent types of analytical uncertainties:1. Geometrical and material data uncertainties 2. Burn-up uncertainties 3. Systematic uncertainties in the transport algorithms (Calc. Bias) 4. Nuclear data uncertainties

Status of nuclear data uncertainty estimation: USA, France: Demand for estimates of nuclear data uncertainties Otherwise nuclear data uncertainties considered to be covered by the safety margin

(which includes errors not accounted for)

We aim to provide a proper estimate for nuclear data uncertainties Ensure bounding estimates in safety margins Reduce conservatism in safety margins

►

Methods for estimating Nuclear Data Uncertainty

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Using Evaluations in Transport Codes

Data Evaluations

Transport Code Library

1. Doppler Broadening (Temperature Effect)

2. Resonance+BG summation

3. Resonance Self-Shielding

4. Data compression / Discretization (Group-wise cross sections)

5. Formatting

Experimental DataModelling, Fitting, Expert Judgement

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Approaches to the estimation ofNuclear Data Uncertainty impact

Generate random nuclear

data library

Perform analysis with random input

data

Store transport

result

1. Perturbation theory

Approximation, Fast!!

2. Monte Carlo

► Retrieve statistics for observable based on distribution of input parameters

All orders included! Flexible Tool!

ji

jiji

CovAAACov,

),()(

SensitivitiesNuclear DataCovariances

draw randomwith

111

)(2

11

2

i

iAN

iANN

NACovN

i

N

i

All rights are reserved, see liability notice.NUDUNA - Meeting on uncertainty propagations in the nuclear fuel cycle, Uppsala, 24/04/2013 - Oliver Buss - AREVA NP GmbH Proprietary © AREVA - p.9

Available Codes for Nuclear Data Uncertainty Estimation

Monte Carlo Approach(All Orders) 1. Order Perturbation

Measured Data TMC (NRG)

Evaluations NUDUNA (AREVA NP)KIWI (LLNL)

Grouped DataXSUSA (GRS) TSUNAMI (ORNL)

TSURFER (ORNL)RIB (CEA)

App

roxi

mat

ions

Very Flexible, CPU intense

FAST!!

Approximations

Long History, Not flexibleVery good Documentation

SCALE Cov based, FAST

Monte-Carlo approach to Nuclear Data Uncertainty Estimation

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NUDUNA:Program Flow

Job card creation

Random library data bench (XML based)

Idealized HEU Shell Exp from LA4208. 2 7 5.0306E-05 1 -2 imp:n=13 2 4.8154E-02 2 -3 imp:n=14 7 5.0306E-05 3 -4 imp:n=15 3 4.8154E-02 4 -5 imp:n=16 7 5.0306E-05 5 -6 imp:n=17 4 4.8152E-02 6 -7 imp:n=18 7 5.0306E-05 7 -8 imp:n=19 5 4.8154E-02 8 -9 imp:n=110 6 4.7780E-02 9 -10 imp:n=111 0 10 imp:n=0

Idealized HEU Shell Exp from LA4208. 2 7 5.0306E-05 1 -2 imp:n=13 2 4.8154E-02 2 -3 imp:n=14 7 5.0306E-05 3 -4 imp:n=15 3 4.8154E-02 4 -5 imp:n=16 7 5.0306E-05 5 -6 imp:n=17 4 4.8152E-02 6 -7 imp:n=18 7 5.0306E-05 7 -8 imp:n=19 5 4.8154E-02 8 -9 imp:n=110 6 4.7780E-02 9 -10 imp:n=111 0 10 imp:n=0

Idealized HEU Shell Exp from LA4208. 2 7 5.0306E-05 1 -2 imp:n=13 2 4.8154E-02 2 -3 imp:n=14 7 5.0306E-05 3 -4 imp:n=15 3 4.8154E-02 4 -5 imp:n=16 7 5.0306E-05 5 -6 imp:n=17 4 4.8152E-02 6 -7 imp:n=18 7 5.0306E-05 7 -8 imp:n=19 5 4.8154E-02 8 -9 imp:n=110 6 4.7780E-02 9 -10 imp:n=111 0 10 imp:n=0

Idealized HEU Shell Exp from LA4208. 2 7 5.0306E-05 1 -2 imp:n=13 2 4.8154E-02 2 -3 imp:n=14 7 5.0306E-05 3 -4 imp:n=15 3 4.8154E-02 4 -5 imp:n=16 7 5.0306E-05 5 -6 imp:n=17 4 4.8152E-02 6 -7 imp:n=18 7 5.0306E-05 7 -8 imp:n=19 5 4.8154E-02 8 -9 imp:n=110 6 4.7780E-02 9 -10 imp:n=111 0 10 imp:n=0

Automated job card multiplication

Automated Output Analysis: Upper/Lower 95/95, Histograms

Generation of random libraries

Parallel execution of jobs: Linux or Windows Cluster

All rights are reserved, see liability notice.NUDUNA - Meeting on uncertainty propagations in the nuclear fuel cycle, Uppsala, 24/04/2013 - Oliver Buss - AREVA NP GmbH Proprietary © AREVA - p.12

NUDUNA: Random input library creation

NUDUNA Scope: Provide libraries for SCALE

and MCNP transport suites Need to generate AMPX and

ACE formatted input files Present Project: Support

ARCADIANUDUNA makes use of: randomLib by AREVA PEPA „NJOY 99“ tool by Los Alamos

National Lab (LANL) SMILER/PUFF IV tool by

Oakridge National Lab (ORNL)

randomLib►Reads information encoded in ENDF6 tapes►Varies information randomly according to covariance matrices►Writes random information to ENDF6 tape

NJOY 99►Resonance + background treatment►Doppler broadening►S(α,β) treatment►Resonance self-shielding►ACE tape generation or multi group treatment

SMILER (PUFF IV)►Converts multigroup format to AMPX

MCNP SCALE

ENDF6 tape

AMPX tapeACE tape

GENDF tape

ARCADIA

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NUDUNA: Creating random ENDF6 tapes

delayedprompttot mmm

File 1: Multiplicities►Restoration of sum rules

►Normal or log-normal model

File 2: Resonances►Respect positivity bounds for widths►Assume constant phases of amplitudes►Dimension ≤ 10.000 ►Normal or log-normal model

File 4: Angular Distributions►Check for angular distribution > 0►Normal or log-normal model

File 3: Cross sections► Define common energy grid acc. to

file 33 information► Average data on grid► Random draws for average data → scaling factors for energy ranges

► Rescale original data ► Restore ENDF6 sum rules

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Problems with current ENDF6 encodings of Data Uncertainties

Missing LTY=0 Entries for Files 1&3 Arbitraryness in restoring sum rules

File 1 phasesCovariances of total and prompt neutron multiplicities must be consistent!Arbitraryness of Distribution ModelsWhy not distribution model in ENDF6? Especially problematic for forward-peaked angular

distributions (File 4)Incomplete Information in File 35 Need for uncertainty of underlying parameters and not of the

sum itself

Results

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Results IGodiva (HEU-MET-FAST-001)

Evaluation Transport Suite

Average keff

Standard Deviaton due to

Nuclear Data Uncertainty

[pcm]

JENDL 4.0SCALE 6238 Groups

0.99891 955

JENDL 4.0 MCNP 5 0.99937 953

ENDF 7.1βSCALE 6238 Groups

0.99900 1016

ENDF 7.1β MCNP 5 0.99920 1018

►Tsunami (SCALE 6): 930 pcm (ENDF/B VII)

Evaluation Transport Suite

Average keff

Standard Deviaton due to

Nuclear Data Uncertainty

[pcm]

JENDL 4.0SCALE 6238 Groups

0.99891 955

JENDL 4.0 MCNP 5 0.99937 953

All rights are reserved, see liability notice.NUDUNA - Meeting on uncertainty propagations in the nuclear fuel cycle, Uppsala, 24/04/2013 - Oliver Buss - AREVA NP GmbH Proprietary © AREVA - p.17

Results II: Adding the benchmark loop

Generate random nuclear data library

Perform Transport calculation for

application case

Apply order statistics to the database of result+bias

→ Upper confidence limit

Evaluate representative Experiments

Store transport result

Extract calc. bias

for application case

All rights are reserved, see liability notice.NUDUNA - Meeting on uncertainty propagations in the nuclear fuel cycle, Uppsala, 24/04/2013 - Oliver Buss - AREVA NP GmbH Proprietary © AREVA - p.18

Results II:Adding the benchmark loop

►Simple Pin-Cell Model: UO2 with 5% enrichment water reflected►Bias estimation based on LCT51 experiments►ck≈0.9 for all experiments

Upper 95%/95%

19.51,...,2.51

)()(181

LCTLCTi

calceffbenchb ikikk

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Results III:Depletion calculations for BUC

►OECD Phase 1b Benchmark, Sample A (3.2 wt.-% enrichment, thermal pin-cell)

►Impact of U238 XS uncertainty based on TALYS

►TRITON / SCALE 6.0

Generate random nuclear

data library

Perform Depletion analysis

Store Isotopic Composition

Sample A

0.0%

0.2%

0.4%

0.6%

0.8%

1.0%

1.2%

1.4%

1.6%

Mo-

95

Tc-9

9

Ru-

101

Rh-

103

Ag-

109

Cs-

133

Nd-

143

Nd-

145

Sm-1

47

Sm-1

49

Sm-1

50

Sm-1

51

Sm-1

52

Eu-

153

Gd-

155

O-1

6

U-2

34

U-2

35

U-2

36

U-2

38

Pu-

238

Pu-

239

Pu-

240

Pu-

241

Pu-

242

Pu-

243

Am-2

41

Am-2

43

Isotope

Rel

. Err

or o

f Num

ber D

ensi

ty

NUDUNA by AREVA

TMC by NRG (Rochman et al.)

Succesful Benchmarks with TMC (NRG)

All rights are reserved, see liability notice.NUDUNA - Meeting on uncertainty propagations in the nuclear fuel cycle, Uppsala, 24/04/2013 - Oliver Buss - AREVA NP GmbH Proprietary © AREVA - p.20

Burnup-Credit with Gd-Fuel

Problem: No experiments for validating Burn-Up of Gd fuel at low burn-up!!!How to estimate uncertainty of number densities? NUDUNA !!!

Variation of 155Gd cross sections according toENDF 7.1β

Assumption: XS uncertainty dominates BU-Algorithm uncertainty

Results:

►155Gd XS uncertainties do not induce seizable relative errors on other number densities

►Expected relative uncertainty of 155Gd number density :

ca. 10%

13 GWd/MTU

0% void

All rights are reserved, see liability notice.NUDUNA - Meeting on uncertainty propagations in the nuclear fuel cycle, Uppsala, 24/04/2013 - Oliver Buss - AREVA NP GmbH Proprietary © AREVA - p.21

SummaryNUDUNA provides nuclear data uncertainty impact estimatesSupport for continuous and group-wise XS librariesNUDUNA improves on the perturbation theory methodologyFlexibility of MC ⇨ easy to embed in hierarchical schemes for uncertainty estimationSuccesful benchmarks for keff and depletion Consistent results for MCNP and SCALE NUDUNA compatible to TSUNAMI (ORNL) Succesful TMC (NRG) vs. NUDUNA benchmarks for OECD Phase-1b

depletion problem

Problems with ENDF6 standard and present evaluations Strong support by Nuclear Data Community needed

End of presentationNUDUNA –“Nuclear Data Uncertainty Analysis in Criticality Safety”Oliver Buss, Axel Hoefer, Jens-Christian NeuberAREVA NP GmbH, PEPA-G (Offenbach, Germany)

Workshop FDN & PEPA08/03/2012