Recently in the WWR-K water-water research reactor the former HEU fuel, enriched to 36% in Uranium- 235, was changed to LEU one, enriched to 19.7%, with substantial change of the core configuration. In view of reactor conversion, a new Safety Analysis Report (SAR) was developed for the WWR-K reactor. Substantiation of reactor safe operation under both normal operation and emergency conditions was done under thermal-hydraulic approach. In the analysis developed prior to physical start up it was assumed that a main circulation pump (MCP) provides the coolant flow rate in the core equal to 350 m 3 /h (a certified value for the pump CB-321). However, in course of the reactor physical start up it was found that it is only 250 m 3 /h. The reason was a decision of the reactor staff to reduce the primary pump power consumption, prolonging its life time.Therefor the thermal hydraulic analysis was revised, and the SAR was renewed. Safety analysis implies also consideration of some potential initiating events capable to develop into an accident. So, several typical initiating events are subject to thermal-hydraulic analysis to substantiate observance of nuclear and radiation safety in emergency situations. It is shown that, owing to proper operation of safety systems, the initiating events under consideration don’t result into accidents, if two primary pumps provide not more than 585 m 3 /h.

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This work is licensed under a Creative Commons Attribution 4.0 International License.