RELAP5 Analysis of Integral Test of the Loss-of-RHR Event During the Mid-Loop Operation
NURETH-14 - 2011 September 25-30

Presented at:
2011 September 25-30
Toronto, Canada
Session Title:
O4-1 BEPU (Best Estimate code Plus Uncertainty) method, CSAU, Statistical Methods

Minoru Yamada (Institute of Nuclear Safety System, Inc.)
Hiroichi Nagumo (MHI Nuclear Engineering Company, Limited)
Ikuo Kinoshita (Institute of Nuclear Safety System, Inc.)


We are developing a statistical safety evaluation method using the RELAP5/MOD3.2 code for

the loss-of-RHR (Residual Heat Removal) event during the mid-loop operation. To confirm

the code prediction performance for gravity injection which is a one of the mitigation

measures for this event, the Bethsy 6.9a test was analyzed using RELAP5/MOD3.2. In the

analytical results, water mass flow rate into the pressurizer in the early period of the transient

event was overpredicted. But water mass flow rate into the pressurizer was able to be

decreased by artificially giving the circulation flow between core and the core bypass region.

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