Dimensional analysis core group

The core thermal-hydraulic calculations are based on the single channel analysis model. On the other hand, the three-dimensional core power distribution is obtained by COREBN for the calculation mesh described in Fig. 2.20 [9]. In the core thermal-hydraulic calculations, the neutron flux calculation mesh of the COREBN is assumed to compose a fuel channel group. The fuel channels in this fuel channel group are assumed to be identical. 

In the Monte Carlo sampling Step 1, the calculations have to be carried out with many groups of input data samples to obtain the statistical distribution of MCST. In order to reduce the required computing time and to ensure accuracy, a subchannel procedure, which is applied in a conservative manner, is adopted for this study. The subchannel analysis for the hot assembly in the core is performed for each group of samples. The hot channel and the hot spot are assumed to be in the hot assembly. Therefore, this closed hot assembly not only has the maximum assembly power, but also has the worst thermal condition in the core. Some results of the three-dimensional core design are used to determine the nominal power distributiOTi and other parameters in the hot assembly. 

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