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? – 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,.... 238U S=250 208Pb 132Sn Regions where fissions take place in terms of KTUY05 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 Burn-up of Actinides in Nuclear Reactors 242Cm 243Cm 244Cm 245Cm 242mAm 10.1h 6h 152y (0.16) 241Am 242Am 243Am 244Am 163d 30y 18.1y 14.9y 238Pu 87.8y 236Np 237Np 2.25h 234U 235U 236U 2.12d 238Np 6.75d 237U 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） 239Pu 240Pu 242Pu 4.96h 243Pu 2.36d 239Np 23.5m 238U 241Pu 16h (0.84) 239U 注）赤字は主要MA核種 （いずれも非核分裂性核種） 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） 注）青→は、数日以内の 短期的崩変 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 Dynamical network calculation Terasawa 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, KajinoFukugita,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 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 T 9(t ) 8.4 exp(t / 7m s) 0.7 3.33105 T 9(t )3 (t ) S Ye=Yp=0.427 Entropy-dependence of rprocess abundance β-delayed fission：Bf-dependence (KTUY-3MeV（left）、MS96（right）) FFMD (Konan model):248Cm, 236U β-delayed fission：FFMD-dependence π J -dependence of CN decay β-decay, ν-反応 TS-1 T fJi Jπ En T J fo T J f Tγ T J fi Bn Bfi Bfo PES Compound T J fo T fiJ T foJ Ex target Tn TS-2 deformation (elongation) Jπ-dependence of compound formation c.s. s波 p波 d波 Decay width Tx Bx T f Tn T U En Bn Tn J En ( ) T ( E ) Target Optical model T OM n J d 0 U T J c ( ) TBA (U )J d 0 Compound Brink-Axel U T fiJ TSi ( , J , )THW ( E fi U )d 0 Transition state Hill-Wheeler Fission Probability • Very strong Jπdependence • No-experimental evidence • How can we verify it？ – Various projectile？(d, 3He, 18O) Level density on the saddle • How to verify it？ 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) Effects of low-lying levels on reaction c.s. G.S. Band Bn of Sn isotopes and HF, DSD c.s. U同位体のBn State-dependence of DSD c.s. Resonances Effects of resonances on MACS Summary • There are many ambiguities in calculation of βdelayed 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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