Application of fractional scaling methodology (FSM) to loss of coolant accidents (LOCA) Part 3. Process level scaling for peak clad TEMPERATURE

Full text of publication follows: Fractional Scaling Methodology (FSM) is demonstrated at the process level for fuel rod heat up in a nuclear reactor core when the primary system is undergoing a large break loss of coolant accident (LBLOCA.). A large number of test facilities were considered. These facilities vary in size from 1/1700 to 1/21 of a full size PWR. The data for LBLOCA from five integral facilities, namely, PBF, semi-scale, LOBI, THTF and LOFT were analyzed, indicating that peak clad temperature (PCT) occurred in the blowdown phase and was mainly a function of linear heating rate. Similarly, the data for reflood phase from eight integral test facilities, namely, semi-scale, FLECHT, FLECHT-SEASET, FLECHT-SKEWED, PKL, LOFT, CCTF, and SCTF were analyzed indicating that the maximum core heat up occurred in the reflood phase and was mainly function of reflood rate. This approach shows that even with large variations in size and shape, the data can be collapsed and the clad temperature can be predicted by a simple expression of one process variable. The spread in data is indication of other process variables. FSM, when applied on the system, component and process levels, serves to synthesize the wealth of worldwide results from analyses and experiments into compact form for efficient storage, transfer and retrieval of information. This is demonstrated on the process level here. As any general scaling method, FSM can also verify the Phenomena Identification and Ranking Table (PIRT). FSM readily identifies differences in component processes and the effects of scale distortion. (authors)