Yuanzineng kexue jishu (May 2022)
Macroscopic Validation of Nuclear Data in Leadbased Reactor Based on VENUS-Ⅱ Facility
Abstract
Lead-based fast reactor (LFR) is one of the advanced reactor concepts elected in the generation Ⅳ forum of international nuclear energy. Lead-based materials, including lead and leadbismuth, are used as coolant in the reactor core. The LFR core has the strong abilities of nuclear fuel proliferation and spent fuel transmutation, which is due to the fact that the neutron spectrum is very hard. The reactor core with the high inherent safety runs at atmospheric pressure, which can reduce the probability of coolant accident loss accident. Leadbased fast reactor is of vital importance to promote the sustainable development of nuclear energy in China. At present, the large uncertainties in the nuclear cross section data still exist in the neutronics simulations in the leadbased reactor. VENUSⅡ leadbased zeropower reactor, in which the neutron flux spectrum is close to that in the lead-based reactor, can be used to carry out the macroscopic validations of nuclear data of the materials in the lead-based reactor. In this paper, the reactor reactivity of VENUS-Ⅱ lead-based zero-power reactor in the supercritical state was measured by the period method, and the effective multiproliferation factor keff was obtained as 1001 14±0000 07. Meanwhile, the leadbased reactor model was accurately built by the MCNP code, and keff of the supcritical reactor in the experiment was calculated by MCNP with four worldwide cross section libraries (ENDF/BⅦ.0, ENDF/BⅦ.1, CENDL-3.1 and JENDL-4.0). The results show that the keff values calculated by the four cross section libraries are in good agreement with the experimentally measured one, and the maximum relative deviation is less than 1%. And the calculated result with ENDF/BⅦ.1 shows a better agreement with the experiment one and the relative and absolute deviations are respectively 025% and 251 pcm. For the interlibrary comparison, a single ENDF/B-Ⅶ.1 element was substituted with other libraries and the small changes in the keff value were calculated by MCNP code. It is found that the lead element causes the largest change in the keff, and the lead nuclear data in CENDL-3.1 and JENDL-4.0 respectively causes the keff change value of 219 pcm and 166 pcm. By comparing the fission rates in the fuel rods, it is concluded that keff values positively correlated with fission rates in the fuel rods. The fission rate results of ENDF/BⅦ.1 and other libraries show the largest difference in the fifth ring fuel rods of the reactor. The neutron spectrum curves calculated by the four libraries are almost consistent, and the shape of the neutron spectra is mainly determined by the nuclear fuel material and the matrix material. In this work, the nuclear data of some materials in the leadbased reactor have been primarily validated, which can provide the important reference for the subsequent neutronics experiments on VENUSⅡ leadbased reactor.
