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Common Nuclear Data Problems for Fission Cycling in r-process and Nuclear Energy

Common Nuclear Data Problems for Fission Cycling in r-process and Nuclear Energy. S. Chiba JAEA. Fission (cycling) in r-process nucleosynthesis. Discovery of Ｔｈ and Ｕ in metal poor stars For realistic calculation of r-process nucleosynthesis Is there a termination point? Where is that?

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Common Nuclear Data Problems for Fission Cycling in r-process and Nuclear Energy

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  1. Common Nuclear Data Problems for Fission Cycling in r-process and Nuclear Energy S. Chiba JAEA

  2. Fission (cycling) in r-process nucleosynthesis • Discovery of Ｔｈ and Ｕ in metal poor stars • For realistic calculation of r-process nucleosynthesis • Is there a termination point?Where is that? • Possibility of SHE generation and discovery of its relics in meteorites • Impacts on universality (56≦Z≦75) • Impacts on nucleo-cosmochronometers • Th/Eu, U/Th, Th/Os,....

  3. 238U S=250 208Pb Supply to medium-weight region by fission, which is less sensitive to the physical conditions of r-process sites 132Sn Continuous flow from the bottom

  4. Regions where fissions take place in terms of KTUY05

  5. Competing processes in calculation of fission cycling • Spontaneous fission • Neutron-induced reactions • Neutron-capture and inverse reaction • Neutron-induced fission  FFMD • β-decay • β-delayed fission  FFMD • β-delayed neutron emission • ν-induced reactions • (ν,e-xn) reaction • (ν,f)  FFMD

  6. Burn-up of Actinides in Nuclear Reactors 242Cm 243Cm 244Cm 245Cm 242mAm 10.1h 6h (0.16) 152y 241Am 242Am 243Am 244Am 163d 30y 18.1y 4.96h 16h (0.84) 14.9y 238Pu 239Pu 240Pu 241Pu 242Pu 243Pu 87.8y 2.12d 2.36d 注）赤字は主要MA核種 　　　（いずれも非核分裂性核種） 236Np 237Np 238Np 239Np 注）青字は核分裂性核種 （核分裂断面積が捕獲断面積の3倍以上） 6.75d 23.5m 2.25h 236U 237U 注）青→は、数日以内の 　　短期的崩変 234U 235U 238U 239U 出典）　オーム社「原子力ハンドブック」および 　　　　　高速炉用ORIGEN2断面積ライブラリ（JENDL3.3）

  7. Critical mass of 235U with various moderators 曲線上の数値は[減速材原子（分子）数]/[235U原子数]を表す

  8. Dynamical network calculationTerasawa et al.,ApJ 562, 470(2001)originally from Prof. Meyer ?? • Reaction rates • Thielamann , Caughlan-Fowler, Maleney-Fowler, Fowler-Hoyle, Rauscher, Mohr, Wagoner, Kajino-Boyd, Orito-Kajino-Mathews, Kajino-Fukugita,Ohsaki, NACRE96 • Nuclear mass • Hilf-Groote-Takahashi (modified) KTUY05 (Prog. Theor. Phys. 305（2005 ）113) • β-decay rates • Klapdor GT-2 with KTUY05 mass, including 1n emission(2007) • ν-induced spallation rate (A(ν,e- xn)A') (x=0, 8) • Langanke (5 ≦ Z ≦100) with dumping • no fission mode ⇒β-delayed fission, spontanious fission(KTUY05) • α-decay (KTUY05 mass) • Data on expanding matter of SNeII : numerically read ⇒ exponential model

  9. Exponential model for expanding nuclear matter c.f. General-relativistic hydro-dynamical simulation by Terasawa, Kajino, Sumiyoshi et al. (ApJ 562, 470(2001))（dots） lower 2 lines : T9 upper 2 lines : density Exponential model Ye=Yp=0.427

  10. Entropy-dependence of r-process abundance

  11. β-delayed fission：Bf-dependence

  12. (KTUY-3MeV（left）、MS96（right）)

  13. FFMD (Konan model):248Cm, 236U

  14. β-delayed fission：FFMD-dependence

  15. Jπ-dependence of CN decay β-decay, ν-反応 TS-1 TS-2 Jπ En Tn Tγ target Ex Bn Bfi Bfo PES Compound deformation (elongation)

  16. Jπ-dependence of compound formation c.s. s波 p波 d波

  17. Decay width Optical model Target Compound Brink-Axel Hill-Wheeler Transition state

  18. Fission Probability • Very strong Jπ-dependence • No-experimental evidence • How can we verify it？ • Various projectile？(d, 3He, 18O)

  19. Level density on the saddle • How to verify it？

  20. Nuclear Structure Effects：SRM-CC • 238U + n • Coupling scheme : G.S. band (0+ - 2+ - 4+ - 6+ - 8+)+4 side bands • Soft Roator Model prediction of coupling strengths • OMP : E.S. Soukhovitsij, S. Chiba et al., J. Phys. G. 30, 905-920(2004). (coupled-levels)

  21. Effects of low-lying levels on reaction c.s. G.S. Band

  22. Bn of Sn isotopes and HF, DSD c.s.

  23. U同位体のBn

  24. State-dependence of DSD c.s.

  25. Resonances

  26. Effects of resonances on MACS

  27. Summary • There are many ambiguities in calculation of β-delayed fission rates, neutron-induced fission rates necessary for fission cycling • Fission barriers, level density (especially at the saddle), their Jπ-dependence, FFMD, deformation parameters and GDR parameters • Neutron binding energies affect the relative magnitude of DSD and HF cross sections • DSD c.s. is sensitive to the presence and energies of the p-states • Nuclear structure (low-lying levels) is important for reaction c.s. calculation

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