Loss-of-pumping accident in the K-reactor and the sensitivity of ECS delivery rate

An analysis of a loss-of-pumping accident (LOPA) in the Savannah River K-reactor has been performed using RELAP5. ECS was assumed to enter the system from only two systems in this case. No boiling occurred in the core during this calculation. Additional calculations were also performed in which the ECS delivery rate was reduced to various predetermined values. The results of those calculations indicated that the system could be adequately cooled with an additional 50% reduction in ECS delivery. A fuel temperature excursion occurred when the ECS delivery rate was reduced to 10% of the baseline calculation. A calculation was also performed with the assumption that the operator failed to activate the ECS. That simulation resulted in fuel melting at approximately 940s (15.7 min). And finally, a comparison of the baseline results obtained using RELAP5 and the results of a comparable calculation using the TRAC code was performed. The results indicate good agreement between the codes. 5 refs., 15 figs., 3 tabs