Assessment of Actinide Decay Data Evaluations: Need for New Measurements Mark A. Kellett

1. Assessment of Actinide Decay Data Evaluations:Need for New MeasurementsMark A. Kellett

2. contents • IAEA CRP “Updated Decay Data Library for Actinides” • Recommendations for new measurements • Published evaluated decay scheme data • Evaluator comments available • Conclusion

3. updated decay data library for actinides • Following an earlier study (1986), the IAEA launched a new Coordinated Research Project (CRP) in 2005, entitled “Updated Decay Data Library for Actinides” • Aim to provide recommended decay data • But also to highlight shortcomings in the available datasets • Evaluations to be undertaken using the DDEP methodology • This includes detailed evaluator comments • Final IAEA report is in press – but data and comments available through the DDEP website: • http://www.nucleide.org/DDEP_WG/DDEPdata.htm

4. Summary article of recommendations Applied Radiation and Isotopes, 70, 1919 (2012) [2012KE05]

5. Radionuclides considered in IAEA CRP

6. Radionuclides – half-life measurements Blue = more data required, Blue = very poor data exist

7. Radionuclides – gamma/X-ray spectrometry Green = gamma, Violet = X-rays

8. Radionuclides – beta spectrometry Blue = more data required

9. Radionuclides – alpha measurements Red = more data required, Yellow= special case

10. Radionuclides – some more details (1) • 252Cf: two sets of data, but one w/o uncertainties • 242Pu: weak transitions to high excited states • 240Pu: weak transitions to 3 states ~960 keV • 237Np: inconsistent with γ-ray data • 238U: only two sets, but one from 2000 (also your new data!) • 236U: only one dataset • 234U: results from one group only • 233U/229Th: 7.6 eV level may α-decay • 231Pa: to support decay scheme

11. Radionuclides – some more details (2) • 228Th: to develop and support decay scheme • 226Ra: two sets of inconsistent data • 224Ra: inconsistent with γ-ray data • 222Rn: early measurements only • 220Rn: from γ-ray data, need to confirm • 218Rn: from γ-ray data, need to confirm • 219At: no data exists • 218At: two very old datasets (1948, 1958) • 217At: minor inconsistencies

12. Radionuclides – some more details (3) • 215At: weak transitions missing • 218Po: scheme based on 1952 β- data • 216Po: from γ-ray data, need to confirm • 214Po: indirect and inadequate data • 210Po: from γ-ray data (pre-1957), to confirm • 212Bi: low intensity transitions required • 211Bi: current datasets discrepant

13. Radionuclides – evaluations (1) • All evaluations, comments and data (in ENSDF and ENDF formats) are available through the dedicated IAEA webpage: • http://www-nds.iaea.org/act_ddl/ • with the IAEA report currently in press. • Alternatively, access to the evaluations, ENSDF files and the evaluators’ comments are also available through the DDEP website: • http://www.nucleide.org/DDEP_WG/DDEPdata.htm

14. Radionuclides – evaluations (2)

15. Radionuclides – detailed comments Detailed comments from evaluators

16. Conclusion • Although the newly available actinide decay data evaluations represent the most comprehensive assessments of current experimental data, individual evaluations only reflect the nature of the measurements on which they are based. Hopefully, the recommendations will help focus experimental resources in the right direction. Your help is needed

17. Thank you for your attention