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Status and needs of activation data for fusion

Status and needs of activation data for fusion. Robin Forrest 1 and Jura Kopecky 2 1 Euratom/UKAEA Fusion Association Culham Science Centre, UK 2 JUKO Research, Alkmaar, The Netherlands.

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Status and needs of activation data for fusion

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  1. 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

  2. Outline • Introduction - activation data • EAF data libraries, used in JEFF and FENDL • EAF-2007 • Suitable for ITER, IFMIF • Contents • Validation and testing • EXFOR • Integral data • SACS • Which nuclides and reactions are important? • Importance diagrams • Uncertainty data • Decay data • Needs • Questions

  3. Introduction • Fusion technology requires good nuclear data for activation calculations • Addressed in Europe by EAF and for ITER by FENDL • What about needs for IFMIF? • Focus is on cross sections, but also need decay data • Uncertainty data also needed, what form should these be, are covariances required? • ‘Issues’ to do with formats for E > 20 MeV • Can 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?

  4. EAF data libraries • Long history of EAF libraries (> 20 years) • Becoming larger and more comprehensive • Part of an activation ‘package’ (EASY) • EAF-2003 is the recommended FENDL/A-2.1 and JEFF-3.1/A special purpose files • Since 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) • Documentation • Validation reports

  5. EAF-2007 • Distributed beginning 2007 • Builds on EAF-2005.1 • Details: • 65,565 n-induced reactions (10-5 eV - 60 MeV) • Isotopes with T½ > 6 hours as targets • 66,864 d-induced reactions • 67,925 p-induced reactions • Decay data for 2,231 nuclides • Uncertainty data for all n-induced reactions • Part 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

  6. Validating and testing EAF libraries • Consider only the n-induced data in EAF-2007 • Huge number (65,565) of reactions • All methods of testing are built into SAFEPAQ-II • Compare 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 type • Uses various statistics in scatter plots • Trend lines, identify outliers • Used to test reactions with no experimental data

  7. Integral measurements • Existing methods of comparison of activation measurements with calculations proceed as follows: • Measure amount of activity by g detector, assign it to particular daughter nuclides • Calculate with an inventory code the predicted activity using the correct materials, irradiation history and neutron spectrum • At a time where a radionuclide dominates calculate C/E for the activity • Present C/E for a range of radionuclides • This can only be done once a data library exists to provide input to the code

  8. EASY method • As before measure amount of activity by g 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 radionuclide • If one pathway is responsible (can be extended) then find the value of the library cross section averaged in the neutron spectrum (sC) • Find sE = sC/ (C/E)activity this is the measured value of the effective cross section • sE 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

  9. 89Y(n,2n)88Y – integral (EAF-2005) Ignore? New data

  10. 89Y(n,2n)88Y – differential Region probed by rez_DF Remains validated

  11. 182W(n,p)182Ta - integral (EAF-2007 prelim) New data Ignore?

  12. 182W(n,p)182Ta - differential (EAF-2007 prelim) Region probed by fzk_ss316 & rez_DF Remains validated (as sum)

  13. Testing large activation libraries – EAF-2007 65,565 reactions 1,715 reactions with differential or integral data 448 reactions with integral data How to test?

  14. 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

  15. Definition of statistics smax D½ Emax

  16. EAF-2005.1 – smax(s) for (n,p) Trend line Discrepant reactions

  17. EAF-2007 – smax(s) for (n,p) Improvement

  18. EAF-2007 – D½(s) for (n,p) 30 MeV 10 MeV Backed by exp

  19. EAF-2007 – D½(s) for (n,a) Outlier Trend

  20. EAF-2007 – smax(s) for (n,2n) new options Can display reactions that are ‘important’ (based on EAF-2003 analysis)

  21. EAF-2007 – s30keV(aU) for (n,g) Odd and Even Z targets New systematic?

  22. Importance diagrams • A neutron spectrum needed for activation calculations • FISPACT output files contain a large amount of data • How to summarize – ideally as a picture? • Importancediagrams give a picture of the dominant nuclides for all neutron energies and all decay times • They are largely independent of the neutron flux • Set of activation calculations for mono-energetic neutrons • Identify dominant nuclides for a quantity e.g. activity • Find regions in (decay time, energy) space where a nuclide contributes more than 50% • Now able to cover energy < 60 MeV

  23. Dose rate importance diagram for Cu E > 20 MeV new. New dominant nuclides? Zn-65 contributes > 50%

  24. Heat output importance diagram for Cr 52V produced by 52Cr(n,p)52V and53Cr(n,d)52V 52V produced by 50Cr(n,g)51Cr(b+)51V(n,g)52V

  25. Importance 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 MeV • 1,314 of the 12,617 reactions needed for all dominant nuclides • Allows focus on important nuclides and reactions • Currently updating with EAF-2007 data • Energy now includes 20 – 55 MeV • Search for new dominant nuclides • Identification of important reactions • This allows a focus on the most relevant nuclides and reactions hence the most significant improvement in data

  26. Importance diagrams for EAF-2007 • New primary nuclides are seen for E > 20 MeV • For V: 48V, 44Sc and 40K • So far data for H – Xe analysed • 15 new primary nuclides • 109 new secondary nuclides • Some 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,da)49V in pathways →39Ar, 42Ar and 44Sc • 18% of 39Ar formed has 54Fe(n,da)49V as first step • For Fe irradiation • EAF-2003, 3 reactions on 54Fe • EAF-2007, 10 reactions on 54Fe

  27. Uncertainty in EAF • Only for n-induced data • 2 – 4 variance values per reaction • No covariance data • Also use DT½ • Can be used by FISPACT → uncertainty on activity etc • Plans to extend this in future (using calculated uncertainties from TALYS by varying parameters) • Are covariances needed? • Large extension to FISPACT so covariances could be used • No data for d- and p-induced libraries • At present no JEFF/A or FENDL/A data

  28. Decay data • Decay data for all nuclides produced in reactions/decays needed for activation calculations • Ongoing work in evaluation of fusion relevant nuclides • Results → JEFF and EAF • Carried 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

  29. Format issues • EAF-2003 converted to ENDF format = JEFF-3.1/A • This can also be done for EAF-2007 but • What about data E > 20 MeV? • At present ~ 50 ‘non-standard’ MT • Could lump to total cross section • Several ways of converting EAF → ENDF • What about uncertainty data?

  30. Development needs (activation) • Include uncertainties for d- and p-induced libraries • Improve uncertainties (more groups) for n-induced library • More differential data especially ~ 20 MeV for n • More integral measurements > 20 MeV for n • Better model calculations for important reactions

  31. Questions • 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?

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