1. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Radiotoxicity and spent fuel

2. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics 235 U 236 U 237 U 237 Np 238 U 237 U 237 Np 237 Np case (n,γ) β (n,2n) Tovesson & Hill, PRC 75 034610 (2007) β

3. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Motivations  Transmutation and incineration of long-lived nuclear wastes : Np, Am, Cm, (Pu ?)  Higher concentration of minor actinides in reactor cores  Need of accurate cross section of actinides

4. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Uranium cycle 238 U + n  239 U  239 Np  239 Pu (fissile) β-β- β-β- 232 Th + n  233 Th  233 Pa  233 U (fissile) β-β- β-β- Thorium cycle 234 U 230 Th 231 Th 232 Th 233 Th 234 Th 231 Pa 232 Pa 233 Pa 234 Pa 235 Pa 232 U 233 U 235 U 236 U 237 U 238 U Neutron Capture  decay  Lower production of minor actinides  Thermal breeder possible, with low fissile inventory

5. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics of fissile nucleus only (capture/fission) We start with 1 fission : -number of destroyed fissile nuclei: 1+ a ( fission+capture) -neutrons needed for next fission: 1+a (fission+capture) -neutrons needed to restore the fissile nucleus (breeding): 1+a -neutrons released by fission: -available additional neutrons: Neutron balance for breeding

6. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Neutron balance for breeding

7. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Concentration of fissile in fuel

8. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Time of flight principle Velocity :

9. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Motivations for fission cross section measurements Need of accurate fission cross sections for actinides - candidates to incineration : 237 Np - involved in the 232 Th/ 233 U : 232 Th, 233 U, 234 U Broad neutron energy spectrum (ADS) up to spallation domain

10. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Detection layout

11. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Détection of the 2 fission fragments High level of rejection for alphas and high energy reactions (>10 MeV) : spallation Fission detection : coincidence method Severe constraint : detectors and target backings very thin

12. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics  f for 234 U

13. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics  f for 237 Np around 40 eV

14. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics  f for 237 Np above threshold

15. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics  f for 209 Bi

16. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics  f for nat Pb

17. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics 234 U 230 Th 231 Th 232 Th 233 Th 234 Th 231 Pa 232 Pa 233 Pa 234 Pa 235 Pa 232 U 233 U 235 U 236 U 237 U 238 U Neutron Capture  decay Future :  f of 231 Pa

18. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Future :  f of 231 Pa

19. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Angular distribution : combination of spins Basically : J combines incident spins and orbital momentum K projection along fission axis If K << J forward peaking If K ~ J sideward peaking (even-even target nucleus) The angular distribution may vary quickly with the energy according to (J,K) of the vibrational resonances

20. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Poor knowledge above 10 MeV 232 Th 237 Np nTOF well suited for describing the quick variations with energy

21. L. Tassan-Got – IPN Orsay Nuclear data and reactor physics Spallation domain ? Tutin et al., NIM A457 (2001) 646 Need to confirm the high anisotropy of 232 Th at high energy