The Need for Nuclear Data

Transcription

1 The Need for Nuclear Data RA Forrest Nuclear Data Section Department of Nuclear Sciences and Applications

2 Themes Nuclear Data underpin all of Nuclear Science and Technology Nuclear Physics Nuclear Data Nuclear Data include static and reaction properties of nuclides Collaborative Effort (Data Centres) Historical Perspective Freely available, but not cost-free to produce R. A. Forrest, NPL, 30 Oct

3 Nuclear Data Nuclear Data involves production and distribution of fundamental data It is not Research, measurement of nuclear properties is (usually) nuclear physics Exception measurements done to resolve data discrepancies Activities: compilation, evaluation, processing, formats, interactive tools R. A. Forrest, NPL, 30 Oct

4 Applications Current reactors Advanced reactors (Gen IV) Fusion Accelerators (ADS) Medical Analytical techniques Basic science (Astrophysics) [Weapons] R. A. Forrest, NPL, 30 Oct

5 Static Nuclide Properties Spin, parity Energy g transition Half-life Mass, decay mode R. A. Forrest, NPL, 30 Oct

6 Static Nuclide Properties ENSDF DDEP LiveChart Nuclear Data Sheets Decay data files (JEFF, ENDF/B) AME NUBASE R. A. Forrest, NPL, 30 Oct

7 Experimental Reaction Data Compilation of journal papers EXFOR International Network of Nuclear Reaction Data Centres EXFOR R. A. Forrest, NPL, 30 Oct

8 EXFOR Details of 20,528 experiments (12,499,461 data points) Searching and visualisation Renormalisation Monitor reactions changed Automatic or manual Ensures that EXFOR data remains relevant for users R. A. Forrest, NPL, 30 Oct

9 Manual Renormalisation Original Corrected R. A. Forrest, NPL, 30 Oct

10 Data for 27 Al(n,p) * = Corrected R. A. Forrest, NPL, 30 Oct

11 Physical cross sections Cross section is a continuous curve, produced by a model code e.g. EMPIRE and TALYS Result determined by choice of parameters (RIPL) Evaluation = Code + Experimental data Complete = All reactions + Uncertainty Collections of evaluations = Library e.g. JEFF, JENDL, ENDF/B R. A. Forrest, NPL, 30 Oct

12 Data for 27 Al(n,p) Uncertainty estimate R. A. Forrest, NPL, 30 Oct

13 Data Libraries Traditional evaluated libraries are not complete New approach (since 2008) are the TENDL libraries (TALYS + Expertise) For TENDL-2013 Incident particles = {n,p,d,t,h,a,g} 2630 Targets, Energy MeV Complete, including covariances Also includes random libraries R. A. Forrest, NPL, 30 Oct

14 Multiple Libraries The various evaluated libraries are different versions of the truth Need to do better! WPEC Subgroup 40 (CIELO) uses international collaboration best evaluation for 1 H, 16 O, 56 Fe, 235,238 U, 239 Pu If successful then need to consider more targets, perhaps as a Network (similar to NRDC) coordinated by IAEA R. A. Forrest, NPL, 30 Oct

15 Needs Nuclear data cycle Measurements EXFOR Applications Model codes Benchmarking DATA LIBRARIES RIPL Processing Evaluations Formatted file R. A. Forrest, NPL, 30 Oct

16 Reaction Data - UK Compilation (EXFOR) Model codes (TALYS) Evaluations (JEFF) Theoretical parameters (RIPL) Processing Benchmarking Measurements R. A. Forrest, NPL, 30 Oct

17 Static Data - UK Structure evaluation (ENSDF) Decay data (DDEP/JEFF) Fission yields (JEFF) Decay heat measurements R. A. Forrest, NPL, 30 Oct

18 Non-technical aspects - UK Fast reactor programme shut (1994) Plutonium is [Asset / Waste] choice = B Waste disposal (repository) Fuel cycle (reprocessing) Energy strategy (long-term energy mix) Civil / Military split (c.f. US) R. A. Forrest, NPL, 30 Oct

19 IAEA NDS Networks (NRDC, NSDD) EXFOR EMPIRE development Evaluations (ENDF/B, JEFF) Standards RIPL Dosimetry (IRDFF) FENDL IBANDL Medical Web tools (LiveChart, ZVView) CRPs R. A. Forrest, NPL, 30 Oct

20 www-nds.iaea.org R. A. Forrest, NPL, 30 Oct

21 Reaction connections Data mining the EXFOR database using network theory J.A. Hirdt, D.A. Brown 87,925 nodes 276,852 edges Importance of standards Photonuclear data R. A. Forrest, NPL, 30 Oct

22 Covariance Connections Correlations Uncertainty as a sum of squares is only true if quantities are uncorrelated Need covariance matrix to propagate uncertainty data correctly If quantities represented by n values then covariance data requires ~n 2 ENDF formatting only allows a subset of covariances to be represented R. A. Forrest, NPL, 30 Oct

23 Covariance The form of covariance depends on how it was produced, it is not measurable, so long as it is mathematically correct then many versions of a covariance matrix are possible Not [Right/Wrong] But [Useful/not Useful] Experimental Theoretical Covariance Useful covariance must be based on ALL available data R. A. Forrest, NPL, 30 Oct

24 Structures and Formats To enable data to be efficiently used they must be stored in an agreed format The ENDF-6 format has been used for decades BUT nearing the end of its life and through WPEC Subgroup 38 a new structure is proposed, implemented in XML format (GND) Many advantages, but modernisation costs R. A. Forrest, NPL, 30 Oct

25 Structures and Formats ENDF-6 formats include details of the product nuclide leads to inconsistency e.g. Q-values incorrect Use a separate product database with links ENSDF and EXFOR in XML (or outputs in XML) will allow better interconnection of data and better answers Practically will need to run ENDF-6 and XML in parallel for several years R. A. Forrest, NPL, 30 Oct

26 Validation Comparison of library data with experiment, typically for a well defined object integral data Results in well defined neutron spectra What can be done when no experiments? R. A. Forrest, NPL, 30 Oct

27 Automatic Validation Thanks: Arjan Koning R. A. Forrest, NPL, 30 Oct

28 Point 1 Unique Nuclide list CIELO evaluations UNIFICATION Renormalized experimental data Cross section Standards R. A. Forrest, NPL, 30 Oct

29 Point 2 Range of Applications RIPL parameter library COMPLETENESS GND format stores more data TENDL - complete libraries R. A. Forrest, NPL, 30 Oct

30 Point 3 Relative measurements Correlation Covariance CONNECTIONS All data in XML Networks collaboration R. A. Forrest, NPL, 30 Oct

31 Point 4 High quality measurements High quality Model codes CORRECTNESS Validation Benchmarking Appropriate processing Application libraries R. A. Forrest, NPL, 30 Oct

32 Nuclear data needs Unification Correctness Resources = Funding + People Completeness Connections R. A. Forrest, NPL, 30 Oct

33 Data Centres Collaboration is carried out in Networks such as NRDC and NSDD For NRDC the Core Centres are: US National Nuclear Data Center OECD NEA Data Bank IAEA Nuclear Data Section Russian Nuclear Data Center Work is much appreciated (Reviews), BUT continued funding essential R. A. Forrest, NPL, 30 Oct

34 Conclusions In UK - little Nuclear data work Internationally - Exciting time Networks and Data Centres working well UK needs better coordination (UKNSF?) Need to be in the club (NEA, IAEA) Collaborate (WPEC SGs, IAEA CRPs) R. A. Forrest, NPL, 30 Oct

35 Thank you! R. A. Forrest, NPL, 30 Oct