Validation of the HOTCHAN code for analyzing the EBR-II driver following loss of flow without scram

A series of experiments involving unprotected (no scram) loss-of-primary flow (LOF) down to natural convection was successfully conducted in February 1985 on the Experimental Breeder Reactor-II (EBR-II). The predicted and measured behavior of a special instrumented assembly, the XX09 fueled INSAT, is compared for the most severe test in the group to demonstrate the validation of the thermal-hydraulic code HOTCHAN. The particular test of interest in this paper was initiated at full power by tripping the primary and secondary pumps. These tests were part of the Shutdown Heat Removal Tests (SHRT) being conducted in EBR-II. The reactor and balance of plant are extensively instrumented and measurements were recorded by a data acquisition system. The reactor and plant response confirm predictions that the driver fuel cladding can survive temperatures above the eutectic threshold for the transient following a station blackout without scramming the reactor. The incore data provide an additional basis for validation of the recently developed HOTCHAN code for analyzing the thermal-hydraulic behavior of specific fuel subassemblies. In this paper the analytical model for HOTCHAN will be described as well as its relationship to the NATDEMO code. The predicted behavior of the hottest driver subassembly is also discussed and comparedmore » with XX09 results.« less