Status and needs of activation data for fusion

Robin Forrest1 and Jura Kopecky2

1 Euratom/UKAEA Fusion AssociationCulham Science Centre, UK

2 JUKO Research, Alkmaar, The Netherlands

This work, supported by the European Communities under the contract of Association between EURATOM/UKAEA, was carried out within the framework of EFDA

OutlineOutlineIntroduction - activation dataEAF data libraries, used in JEFF and FENDLEAF-2007

Suitable for ITER, IFMIF Contents

Validation and testing EXFOR Integral data SACS

Which nuclides and reactions are important?Importance diagramsUncertainty dataDecay dataNeedsQuestions

IntroductionIntroduction

Fusion technology requires good nuclear data for activation calculations

Addressed in Europe by EAF and for ITER by FENDLWhat about needs for IFMIF?Focus is on cross sections, but also need decay dataUncertainty data also needed, what form should these

be, are covariances required?‘Issues’ to do with formats for E > 20 MeVCan subsets of important nuclei and reactions be

defined?How are data validated and tested?Are new data libraries required or should existing ones

be extended and improved?

EAF data librariesEAF data librariesLong history of EAF libraries (> 20 years)Becoming larger and more comprehensivePart of an activation ‘package’ (EASY)EAF-2003 is the recommended FENDL/A-2.1 and JEFF-

3.1/A special purpose filesSince then:

EAF-2005 (60 MeV)EAF-2005.1 (60 MeV, d-induced)EAF-2007 (60 MeV, d-induced, p-induced)

EAF contains (simple) uncertainty data for all n-induced reactions

Decay data (consistent with cross sections)DocumentationValidation reports

EAF-2007EAF-2007

Distributed beginning 2007Builds on EAF-2005.1Details:

65,565 n-induced reactions (10-5 eV - 60 MeV) Isotopes with T½ > 6 hours as targets

66,864 d-induced reactions67,925 p-induced reactionsDecay data for 2,231 nuclidesUncertainty data for all n-induced reactionsPart of EASY-2007

Documentation available on web site (http://fusion.org.uk/easy2007/)

Cross section data > 20 MeV and d- and p- induced data suitable for IFMIF

Validating and testing EAF librariesValidating and testing EAF libraries

Consider only the n-induced data in EAF-2007Huge number (65,565) of reactionsAll methods of testing are built into SAFEPAQ-IICompare with EXFOR (~1,700 reactions)Compare to integral data (~ 450 reactions)Only a small fraction of library can be compared to exp.Statistical Analysis of Cross Sections (SACS) method

Look at all reactions for each reaction typeUses various statistics in scatter plotsTrend lines, identify outliersUsed to test reactions with no experimental data

Integral measurementsIntegral measurements

Existing methods of comparison of activation measurements

with calculations proceed as follows:Measure amount of activity by detector, assign it to particular

daughter nuclidesCalculate with an inventory code the predicted activity using

the correct materials, irradiation history and neutron spectrumAt a time where a radionuclide dominates calculate C/E for the

activityPresent C/E for a range of radionuclides

This can only be done once a data library exists to provide input to the code

EASY methodEASY methodAs before measure amount of activity by detector, run

inventory code and calculate (C/E)activity

Use the FISPACT pathways method to determine the

pathways that are responsible for the production of each

radionuclideIf one pathway is responsible (can be extended) then find

the value of the library cross section averaged in the neutron spectrum (C)

Find E = C / (C/E)activity this is the measured value of the effective cross section

E is input into SAFEPAQ-II in the same way as other experimental data

During the development of the next data library the preliminary data can be adjusted using the integral data

8989Y(n,2n)Y(n,2n)8888Y – integral (EAF-2005)Y – integral (EAF-2005)Integral C/E for Y-89(n,2n)Y-88

C/E

Neutron Spectrum

C/E = 0.8621

C/E = 1.1112

C/E = 1.0259

C/E = 1.1378

C/E = 1.4887

1.10

0.91

0.80

1.00

1.20

1.40

1.60

fns_7hour fns_5min fng_Y tud_Y rez_DF

New data

Ignore?

Y-89(n,2n)Y-88

Final

Cro

ss s

ection (

b)

Energy (eV)

0.0E+00

3.0E-01

6.0E-01

9.0E-01

1.2E+00

1.5E+00

1.0E+07 2.0E+07 3.0E+07 4.0E+07 5.0E+07 6.0E+07

SystmPAT79RI 99KGU00LAS75KYU79MOH84ANL87BRC81LAS75KOS81FEI89FEI89SAV98BRC02RI 99LAS75AUB76JAE93LAS77AEP89

8989Y(n,2n)Y(n,2n)8888Y – differentialY – differential

Region probed by rez_DF

Remains validated

Integral C/E for W-182(n,p)Ta-182C

/E

Neutron Spectrum

C/E = 1.0621

C/E = 0.8521

C/E = 1.0667

C/E = 1.2081 C/E = 1.2009

C/E = 0.1542

C/E = 1.3182

1.20

0.83

0.00

0.50

1.00

1.50

sneg_1 sneg_1 fzk_ss316

fng_tung.asc sneg_2 fzk_2 rez_DF

182182W(n,p)W(n,p)182182Ta - integralTa - integral (EAF-2007 prelim) (EAF-2007 prelim)

Ignore?

New data

W-182(n,p)Ta-182

Final

Cro

ss s

ectio

n (b

)

Energy (eV)

0.0E+00

5.0E-03

1.0E-02

1.5E-02

2.0E-02

2.5E-02

0.0E+00 1.0E+07 2.0E+07 3.0E+07 4.0E+07 5.0E+07 6.0E+07

SystmSys20RI 03RI 03KOS93JUL75 gJUL75 nLRL59LNZ97NAG92 nRI 03RI 03 n

182182W(n,p)W(n,p)182182Ta - differential Ta - differential (EAF-2007 prelim) (EAF-2007 prelim)

Remains validated (as sum)

Region probed by fzk_ss316 & rez_DF

Testing large activation libraries – EAF-2007Testing large activation libraries – EAF-2007

65,565 reactions

448 reactions with integral data

1,715 reactions with differential or integral data

How to test?

Statistical analysis of cross sections (SACS)Statistical analysis of cross sections (SACS)

Systematics show that measured cross sections at particular energies have a good correlation with parameters such as A or s = (N - Z) / A

Work on maximum cross sections by Manokhin for (n,2n) shows similar trend

Such data easily extracted from EAF-2007 or one of the data sources and displayed as scatter plot against A, Z or s

Trend lines can be added and reactions discrepant from the trend identified

Ti-50(n,2n)Ti-49

Final

Cro

ss s

ectio

n (b

)

Energy (eV)

0.0E+00

2.0E-01

4.0E-01

6.0E-01

8.0E-01

1.0E+00

1.0E+07 2.0E+07 3.0E+07 4.0E+07 5.0E+07 6.0E+07

Definition of statisticsDefinition of statistics

max

Emax

½

EAF-2005.1 – EAF-2005.1 – maxmax((ss) for (n,p)) for (n,p)(n,p) for Final

Max

cro

ss s

ectio

n (b

)

Asymmetry (s)

1E-03

1E+01

1E-02

1E-01

1E+00

0.00 0.05 0.10 0.15 0.20 0.25

Trend line

Discrepant reactions

(n,p) for FinalNO A<20

Max

cro

ss s

ectio

n (b

)

Asymmetry (s)

1E-03

1E+01

1E-02

1E-01

1E+00

0.00 0.05 0.10 0.15 0.20 0.25

EAF-2007 – EAF-2007 – maxmax((ss) for (n,p)) for (n,p)

Improvement

(n,p) for FinalScore = 0 Score > 0

Wid

th a

t ha

lf-m

ax X

S (

eV)

Asymmetry (s)

0E+00

1E+07

2E+07

3E+07

4E+07

5E+07

0.00 0.05 0.10 0.15 0.20 0.25

EAF-2007 – EAF-2007 – ½½((ss) for (n,p)) for (n,p)

Backed by exp

10 MeV

30 MeV

(n,a) for Final

Wid

th a

t ha

lf-m

ax X

S (

eV)

Asymmetry (s)

0E+00

1E+07

2E+07

3E+07

0.00 0.05 0.10 0.15 0.20 0.25

EAF-2007 – EAF-2007 – ½½((ss) for (n,) for (n,))

Trend

Outlier

(n,2n) for FinalNot important Important

Max

cro

ss s

ectio

n (b

)

Asymmetry (s)

1E-02

1E+01

1E-01

1E+00

0.00 0.05 0.10 0.15 0.20 0.25

EAF-2007 – EAF-2007 – maxmax((ss) for (n,2n) new options) for (n,2n) new options

Can display reactions that are ‘important’ (based on EAF-2003 analysis)

(n,g) for FinalEven Z Odd Z

Cro

ss s

ectio

n: 3

0.0

keV

(b)

aU

1E-05

1E+01

1E-04

1E-03

1E-02

1E-01

1E+00

0 25 50 75 100 125 150 175 200

EAF-2007 – EAF-2007 – 330keV0keV((aUaU) for (n,) for (n,))

Odd and Even Z targets New systematic?

Importance diagramsImportance diagrams

A neutron spectrum needed for activation calculationsFISPACT output files contain a large amount of dataHow to summarize – ideally as a picture?Importance diagrams give a picture of the dominant nuclides

for all neutron energies and all decay timesThey are largely independent of the neutron fluxSet of activation calculations for mono-energetic neutronsIdentify dominant nuclides for a quantity e.g. activityFind regions in (decay time, energy) space where a nuclide

contributes more than 50%Now able to cover energy < 60 MeV

Dose rate importance diagram for CuDose rate importance diagram for Cu

Zn-65 contributes > 50%

E > 20 MeV new. New dominant nuclides?

Heat output importance diagram for CrHeat output importance diagram for Cr

52V produced by 50Cr(n,)51Cr()51V(n,)52V

52V produced by 52Cr(n,p)52V and 53Cr(n,d)52V

Importance diagramsImportance diagrams

Diagrams for all elements (EAF-2003) in ‘Activation Handbook’ (544 pages)

Analysis shows:754 of the 1,917 nuclides describes activation properties of all

elements < 20 MeV1,314 of the 12,617 reactions needed for all dominant nuclidesAllows focus on important nuclides and reactions

Currently updating with EAF-2007 dataEnergy now includes 20 – 55 MeVSearch for new dominant nuclidesIdentification of important reactionsThis allows a focus on the most relevant nuclides and

reactions hence the most significant improvement in data

Importance diagrams for EAF-2007Importance diagrams for EAF-2007New primary nuclides are seen for E > 20 MeV

For V: 48V, 44Sc and 40K So far data for H – Xe analysed

15 new primary nuclides109 new secondary nuclidesSome swapping of primary ↔ secondary

New primary nuclides 7Be, 11C, 48Ca, 50Cr, 66Ga, 72As, 76Br, 82mRb, 86Y, 108Cd, 114Cd,

109Sn, 124Sn, 124I and 124Xe‘Exotic’ reactions seen for E > 20 MeV

54Fe(n,d)49V in pathways → 39Ar, 42Ar and 44Sc18% of 39Ar formed has 54Fe(n,d)49V as first step

For Fe irradiationEAF-2003, 3 reactions on 54FeEAF-2007, 10 reactions on 54Fe

Uncertainty in EAFUncertainty in EAF

Only for n-induced data2 – 4 variance values per reactionNo covariance dataAlso use T½

Can be used by FISPACT → uncertainty on activity etcPlans to extend this in future (using calculated uncertainties

from TALYS by varying parameters)Are covariances needed?Large extension to FISPACT so covariances could be usedNo data for d- and p-induced librariesAt present no JEFF/A or FENDL/A data

Decay dataDecay data

Decay data for all nuclides produced in reactions/decays needed for activation calculations

Ongoing work in evaluation of fusion relevant nuclidesResults → JEFF and EAFCarried out by Serco (Alan Nichols)Currently 21 nuclides are being evaluated:45mSc, 70Ga, 71Ge, 75Ge, 75mGe, 79Se, 90Y, 90mY, 90Nb, 90mNb,

98Tc, 113Cd, 113mCd, 121Sn, 121mSn, 166Dy, 170Tm, 176mYb, 184Re, 189mOs, 190Pt

Results will be included in EAF-2009

Format issuesFormat issues

EAF-2003 converted to ENDF format = JEFF-3.1/AThis can also be done for EAF-2007 but

What about data E > 20 MeV?At present ~ 50 ‘non-standard’ MTCould lump to total cross sectionSeveral ways of converting EAF → ENDFWhat about uncertainty data?

Development needs (activation)Development needs (activation)

Include uncertainties for d- and p-induced librariesImprove uncertainties (more groups) for n-induced libraryMore differential data especially ~ 20 MeV for nMore integral measurements > 20 MeV for nBetter model calculations for important reactions

QuestionsQuestions

Do we need a FENDL/A-3 library?EAF-2007 available, should this be recommended for a new

FENDL activation library?Should d- and p-induced data be included?Should uncertainty data be included?Should FENDL ‘add value’ by improving a subset of

reactions or uncertainty data?New measurements?Formats?What about validation?Time scale?