核电厂压力容器材料在49-2反应堆的辐照技术研究

Irradiation Technology for NPP Reactor Pressure Vessel Material in 49-2 SPR

应用MCNP程序对堆芯建模,计算得出辐照孔道内距堆心底部高25 cm处的中子能谱,结合多箔活化法测量结果,通过SANDII程序解谱得出该位置的快中子注量率;通过相对快中子注量率测量,获得孔道内轴向快中子注量率分布,从而确定辐照时长和辐照方案,使样品辐照达到快中子（E≥1 Me V）注量6×1019cm-2的技术指标。为完成辐照样品解体,应用ORIGEN2程序计算,获得待解体样品源项;使用MCNP程序对解体时的操作环境进行建模,计算得出不同屏蔽层厚度的γ剂量率数据;与实测结果进行对比,计算结果与实测结果符合较好,证明屏蔽设计有效。本次辐照考验完全满足技术指标。。

By setting up a model for the reactor core, calculation of the fast neutron energy spectrum of the position 25 cm above the bottom of the irradiation tube can be realized. Combining the results of the calculation and the multiple foil activation method measurement, the fast neutron fluence rate can be obtained by unfolding the spectrum with SANDII code. Adopting the relatively fast neutron fluence rate measurement, the distribution of the axial fast neutron fluence rate can be obtained, and, the hour-length and the scheme of the irradiation can be defined. The technique target fast neutron （E≥1 MeV） flux received by the sample reaches about 6× 10^19 cm^-2. For accomplishing the sample disassembly, firstly we obtained the radioactive source term of the sample by calculating with ORIGEN2 code. Then, according to the operating environment, a model was set up by MCNP code, and the gamma dose rate data in different Shielding layer thickness was obtained by calculating with the code. The comparison between the calculation result and the measurement result indicated that the shielding design was effective. This irradiation experiment completely satisfied the technique target.