Double-Differential Measurements of Cm-248
Double-Differential Prompt Neutron Spectra Measurements in 248cm Spontaneous Fission. Calculation and Evaluation of Prompt Neutron Spectra in Fission of Neptunium, Americium and Curium Isotopes
Tech Area / Field
- FIR-NOT/Nuclear and Other Technical Data/Fission Reactors
3 Approved without Funding
Khlopin Radium Institute, Russia, St Petersburg
Project summaryThe development of radioactive waste transmutation technologies involves the high-accuracy nuclear data needs. One of the two most promising concepts of plutonium and minor actinide destruction - the fast-neutron actinide burner reactor (ABR) application - entails the necessity of precision neutron data in minor actinide fission, because the own neutron flux of ABR is mainly generated by fission of neptunium, americium and curium isotopes. Newer evaluation of prompt neutron spectrum (FNS) could also result in accuracy growth of reactor dose calculations and in the expensive stock reduction of the nuclear reactor defense.
Experimental information on PNS of minor actinide fission is very limited (besides that in 252Cf SF and 235U TF), because of the objective problems of continues high-accuracy measurements in a wide energy range. It is obviously that the achievement of the accuracy required (1% of the average neutron energy uncertainties) even in fission of high priority isotopes by the experimental methods and further evaluation will take great efforts of a large number of the research groups. The development of phenomenological method of PNS calculation based on newer integral and differential data as well as on revised theoretical approach seems to be more expedient approach for the improvement of minor actinide data. The goal of the Project proposed is the comprehensive study of neutron emission by means of double-differential PNS measurements versus fragment masses and total kinetic energies (TKE) in 248Cm fission. Being based on the neutron data be obtained as well as on that are measured in 252Cf spontaneous and 235U thermal neutron induced fission, the substantial revising of PNS model calculation parameters in the framework of Mauser Feshbach statistical approach will be done. Additional de-excitation channel of nonstatistical neutron emission will be included to the calculation. The newer evaluation of PNS in spontaneous fission of 244Cm, 246Cm, 248Cm and neutron induced fission of 237Np, 239Pu, 241Am, 242MAm, 243Cm and 245Cm will be performed with use of the revised model calculations as a criteria of experimental data reliability.
High-precision neutron spectrometer for study both spontaneous and induced fission will be used for double-differential PNS measurements. It includes a fission chamber and an array of stilbene, 6LiJ(Eu) and NE-213 neutron detectors. Special fragment detection methods (copyright certificates on the fragment detectors invention), various types of neutron detectors application, original features of data treatment and corrections have allowed to carry out the high-accurate measurements of double-differential PNS in 252Cf SF. The results of the measurements have been included to the 252Cf SF PNS standard evaluation. The spectrometer has also been used at PNS measurements in SF of 248Cm and 246Cm.
Modified version of "SCOFIN" code will be employed to perform a statistical PNS calculation. The code has been powerfully used for neutron data calculation in 252Cf SF. The code consistently considers a fragment spin, level density dependence on excitation energy and competition of neutron and gamma-quanta emission.
Japan Atomic Energy Research Institute has been developing a concept of a transmutation system of minor actinide based on the Actinide Burner Reactor (ABR) application. The scientific cooperation with JAERI will yield an in substantial progress in basic research for supporting the development of ABR.
Collaboration with the leading experts from Los Alamos National Laboratory (USA) and Physicalish-Technische Bundesanstalt (Germany) would result in comprehensive revision of existing methods of PNS calculations. In particular, the development of nonstatistical neutron emission approach is the essentially new point in calculations.
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