Cross Sections for239Pu(n,f) and241Pu(n,f) in the RangeEn= 0.01 eV to 200 MeV

Tôvesson, F.; Hill, T. S.

doi:10.13182/nse09-41

“…[48]). (vi) Our computed 241 Pu neutron-induced fission cross section lies between the two measurements by Tovesson et al [49] and Szabo et al [50]. The high-precision data from Tovesson et al [49], although resulting from a well-tested technique, are 20%-30% lower than the standard evaluations and need to be confirmed.…”

Section: Fission Cross Sections Calculated Over a Suite Of Pu Isotsupporting

confidence: 54%

“…Readers may refer to Appendix C to visualize the sensitivity to choice of barrier height parameters in the case of a fissile nuclide. [49] and Shcherbakov et al [51]. The 237 Np( 3 He,df ) 238 Pu * fission probability measurement from Back et al [52], transposed in terms of fission cross section, is the unique experimental data support for the ( 237 Pu + n) system.…”

Section: Fission Cross Sections Calculated Over a Suite Of Pu Isotmentioning

confidence: 99%

R-matrix analysis and prediction of low-energy neutron-induced fission cross sections for a range of Pu isotopes

Bouland

¹

,

Lynn

²

,

Talou

³

2013

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Neutron-induced fission cross sections for the plutonium isotopes from 236 to 244 are computed for neutrons of a few keV up to 5.5 MeV incident energy, using the Hauser-Feshbach statistical theory of nuclear reactions, modified to treat the fission decay channel in the R-matrix formalism. The fluctuations of the fission decay widths owing to the presence of intermediate structures in the second well and to the coupling of class I and class II states are simulated by Monte Carlo sampling of the underlying model parameter distributions. The accuracy of this approach is tested relative to the results of well-known analytical formulations for the average fission cross sections. Special attention is paid to the choice and consistency of the model input parameters, in part obtained from microscopic nuclear structure calculations. The predictive capabilities offered by our method are tested against the neutron-induced fission of the very short-lived 243 Pu (τ 1/2 = 4.95 h) for which no measurement exist. Our calculations, consistent over all the Pu isotope series, demonstrate that 243 Pu is fissile, in contrast to what is reported in the standard ENDF/B-VII.1 and JEFF-3.1.2 evaluated libraries. No recommendations are made in the JENDL-4.0 data library for this isotope.

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“…Use of these isotopes will require careful experimental conditions to reduce the background effects from the decay of the target material. Recently, the 241 Pu cross section has been measured directly using neutron time-of-flight [28]. Uncertainties of less than 1% are reported for the 10 -20 MeV neutron range.…”

Section: Discussionmentioning

confidence: 99%

Surrogate measurement of thePu238(n,f) cross section

Ressler

¹

,

Burke

²

,

Escher

³

et al. 2011

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The neutron induced fission cross-section of 238 Pu was determined using the Surrogate Ratio Method (SRM). The (n, f ) cross section over an equivalent neutron energy range of 5 -20 MeV was deduced from inelastic α-induced fission reactions on 239 Pu, with 235 U(α, α f ) and 236 U(α, α f ) used as references. These reference reactions reflect 234 U(n, f ) and 235 U(n, f ) yields, respectively. The deduced 238 Pu(n, f ) cross section agrees well with standard data libraries up to ∼10 MeV, although larger values are seen at higher energy. The difference at higher energy is less than 20%.

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“…Use of these isotopes will require careful experimental conditions to reduce the background effects from the decay of the target material. Recently, the 241 Pu cross section has been measured directly using neutron time-of-flight [28]. Uncertainties of less than 1% are reported for the 10 -20 ,x) surrogate reactions, where x is a deuteron, triton, or alpha particle [29].…”

Section: Discussionmentioning

confidence: 99%

Surrogate measurement of the 238Pu(n,f) cross section

Ressler¹,

Burke²,

Escher³

et al. 2010

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The neutron induced fission cross-section of 238 Pu was determined using the Surrogate Ratio Method (SRM). The (n, f ) cross section over an equivalent neutron energy range of 5 -20 MeV was deduced from inelastic α-induced fission reactions on 239 Pu, with 235 U(α, α f ) and 236 U(α, α f ) used as references. These reference reactions reflect 234 U(n, f ) and 235 U(n, f ) yields, respectively. The deduced 238 Pu(n, f ) cross section agrees well with standard data libraries up to ∼10 MeV, although larger values are seen at higher energy. The difference at higher energy is less than 20%.

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Cross Sections for²³⁹Pu(n,f) and²⁴¹Pu(n,f) in the RangeE_n= 0.01 eV to 200 MeV

Cited by 46 publications

References 16 publications

R-matrix analysis and prediction of low-energy neutron-induced fission cross sections for a range of Pu isotopes

R-matrix analysis and prediction of low-energy neutron-induced fission cross sections for a range of Pu isotopes

Surrogate measurement of thePu238(n,f) cross section

Surrogate measurement of the 238Pu(n,f) cross section

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