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 leadbismuth, 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. Leadbased 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 leadbased reactor. VENUSⅡ leadbased zeropower 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 supercritical state was measured by the period method, and the effective multiproliferation factor keff was obtained as 1001 14±0000 07. Meanwhile, the leadbased reactor model was accurately built by the MCNP code, and keff of the supcritical reactor in the experiment was calculated by MCNP with four worldwide cross section libraries (ENDF/BⅦ.0, ENDF/BⅦ.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/BⅦ.1 shows a better agreement with the experiment one and the relative and absolute deviations are respectively 025% and 251 pcm. For the interlibrary 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/BⅦ.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 leadbased reactor have been primarily validated, which can provide the important reference for the subsequent neutronics experiments on VENUSⅡ leadbased reactor.

Key words: VENUS-Ⅱ, period method, effective multiplication factor, Monte Carlo simulation, nuclear data

摘要： 为提高铅基堆中子学模拟的可靠性，基于启明星Ⅱ号铅基零功率反应堆，开展铅基堆相关核数据的入堆宏观基准检验研究。采用周期法测量堆芯反应性，进而获得有效增殖因数keff为1001 14±0000 07。采用MCNP程序对铅基堆进行精细化建模，结合不同数据库内的中子评价核数据，计算实验燃料棒装载下的铅基堆芯的keff。比较结果可知，4种截面库计算的铅基堆keff模拟结果与实验结果吻合较好，最大相对偏差小于1%，其中，ENDF/BⅦ.1库的模拟结果与实验结果吻合最好，相对偏差和绝对偏差分别为025%和251 pcm。通过计算关键材料元素核数据引起keff的变化量，可知铅元素核数据引起的堆芯keff结果的波动量最大，在CENDL31和JENDL40中的铅元素引起keff的波动值分别为219 pcm和166 pcm。

关键词: 启明星Ⅱ号, 周期法, 有效增殖因数, MCNP模拟, 核数据