Measurement of the Neutron Fission and Capture Cross Sections for ²³³U in the Energy Region 0.4 to 2000 eV

Abstract

The neutron capture cross section and f i s s i o n cross section far 2 3 3 ~ have been measured simultaneously in the neutron energy range from 0.4 t o 1000 eV. The data a r e presented i n graphical, tabular, and i n t e g r a l farm. Cornpaxisons w i t h previously published data, using similar and different methods, are given, *Work sponsored by the U, 5. Atomic Energy Commission under contracts w i t h Oa& Ri'dge National Labosatoq ( W-"/o? -eng-26) and Rensselaer Polytechnic Ins.titute [.AT( 30-3) -328 1, *Dep&rtment of' Nuclear Engineering and Science, Rensselaer Polytechnic I n s t i k t e . +Presen.t address: Los AIwos S c i e n t i f i c Laboratory.NOTICE This rlnrtfimertt rmtoin(i infmnntim atid was p r p p d primarily far internal use ot Laboratory. Ir i s subjec? tc revision or corre not tqxesent a final report. preliminary noturn Oak Ridge lrlotionul end therefare does DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government.

Review and Assessment of Neutron Cross Section and Nubar Covariances for Advanced Reactor Systems

“…6 240 Pu(n, el) 2.7 242 Pu(n, el) 2.8 242 Cm(n, el) 2.9 244 Cm(n, el) 2.10 235 U(n, el) 2.11 233 U(n, el) 2.12 239 Pu(n, el) 2.13 241 Pu(n, el) 2.14 243 Cm(n, el) 2.15 245 Cm(n,el) 2. 16 237 Np(n, el) 2.17 241 Am(n, el) 2.18 243 Am(n, el) 2.19 242m Am(n, el) Chapter 3: Fission Cross Sections 3.1 232 Th(n, f) 3.2 238 U(n, f) 3.3 236 U(n, f) 3. 4 234 U(n, f) 3.5 238 Pu(n, f) 3.6 240 Pu(n, f) 3.7 242 Pu(n, f) 3.8 242 Cm(n, f) 3.9 244 Cm(n, f) 3.10 235 U(n, f) 3.11 233 U(n, f) 3.12 239 Pu(n, f) 3.13 241 Pu(n, f) 3.14 243 Cm(n, f) 3.15 245 Cm(n, f) 3.16 237 Np(n, f) 3.17 241 Am(n, f) 3.18 243 Am(n, f) 3.19 242m Am(n, f) Chapter 4: Inelastic Scattering 4.1 232 Th(n, n' 4.2 238 U(n, n') 4.…”

“…6 240 Pu(n, n') 4.7 242 Pu(n, n') 4.8 242 Cm(n, n') 4.9 244 Cm(n, n') 4.10 235 U(n, n') 4.11 233 U(n, n') 4.12 239 Pu(n, n') 4.13 241 Pu(n, n') 4.14 243 Cm(n, n') 4.15 245 Cm(n, n') 4. 16 237 Np(n, n') 4.17 241 Am(n, n') 4.18 243 Am(n, n') 4.19 242m Am(n, n') Chapter 5: Capture Cross Sections 5.1 232 Th(n, gamma) 5. 2 238 U(n, gamma) 5.…”

“…Notwithstanding the years of experimental and theoretical efforts, the evaluated capture, (n,2n), neutron inelastic and inelastic scattering cross sections of most thoroughly investigated nuclides like 232 Th, 235 U, 238 U or 239 Pu in major data libraries differ a lot. Since these cross sections are obtained (or might be obtained) via Hauser-Feshbach model calculations, the part of the differences might be attributed to the unjustified simplifications in modeling excited nucleus (either composite, compound or residual) energy spectra or neutron-nucleus interactions.…”

“…Major source of discrepancies in case of inelastic scattering on 232 Th or 238 U targets are the coupling strengths of the deformed optical potential [6,7]. Experimental data on inelastic neutron scattering are analyzed in a Hauser-Feshbach-Moldauer approach using a coupled channel estimates of the direct inelastic scattering.…”

“…For the direct excitation of the 238 , a soft-deformable rotator model was used [6,7]. Quadrupole, octupole, hexadecapole and gamma-deformation parameters were defined by consistent analysis of excited rotational-vibrational band structures and excitation cross section of the relevant excited levels of 232 Th or 238 U. Structures evident in measured neutron emission 1 2 spectra for En ~1 -6 MeV are correlated with excitation of levels of K =0 -and K =0 2 + , 0 2 + , 2 2 + bands.…”