| Popis: |
A conventional two-step approach of a transport calculation and a nodal diffusion calculation, such as CASMO/SIMULATE, APOLLO/SMART, was used in the light water reactor core design for decades. A new PWR core nuclear design software package named TORCH V20 was developed by Nuclear Power Institute of China (NPIC), and many advanced methodologies were implemented in TORCH V20 to enhance accuracy and performance. Based on the twostep calculation scheme, TORCH V20 mainly contains lattice physics code for assembly homogenization, link calculation code for fewgroup constant parameterization and core simulation code for fewgroup core calculation. The onestep direct heterogeneous calculation code KYLIN V20 based on finegroup structure was employed. KYLIN V20 was used to generate the homogenized parameters, including homogenized crosssection, diffusion coefficients, discontinuity factors and so on. Considering the fact that a certain state required by the reactor core calculation may be different from the ones provided by KYLIN V2.0, a process was required to provide a table between those neutronics few-group constants and state parameters based on the discrete points provided by lattice calculations. The code named PACFAC was used to provide the table for the core simulation code CORCA3D. The neutron diffusion equation would be calculated for core fuel management in CORCA3D. The calculation modules of each code were already verified against various benchmark problems, whereas the work presented in this paper focuses on the verification and validation (V&V) of linked code system TORCH V20 for the core design of pressurized water reactors (PWRs). The measured values of reactor startup physics test and nuclear power plant operation from six PWR NPPs (Daya Bay NPP, Ling’ao NPP, Fangjiashan NPP, Qinshan NPP, Hainan Changjiang NPP, Fuqing NPP) were utilized to do the comparison and analysis for V&V. Part of the reactor startup physics tests and a total of 85 cycles of 14 NPP units were simulated by TORCH V2.0. However, the content of the reactor startup physics tests varies in different cycles. Compared parameters of reactor startup physics test contain critical boron concentration, control rod integral value, boron differential value and isothermal temperature coefficient. Compared parameters of nuclear power plant operation contain critical boron concentration, assemblywise power distribution, hot spot factor and nuclear enthalpy rise factor. With the exception of very few results of critical boron concentration for some deep operation cycles, all the results of compared parameters are in good accordance with the measured values, which are agreed with the industrial acceptance criteria. The results show that the software TORCH V20 has reliable calculation ability and is applicable to the PWR nuclear power engineering design which is based on square fuel assembly. In the future, the uncertainty analysis of TORCH V20 would be carried out for the comprehensive verification and validation. |
