Abstract
The code assessment typically comprises basic tests cases, separate effects test, and integral effects tests. On the other hand, the thermal hydraulic system codes like RELAP5/MOD3.3 are primarily intended for simulation of transients and accidents in light water reactors. The plant measured data come mostly from startup tests and operational events. Also, for operational events the measured plant data may not be sufficient to explain all details of the event. The purpose of this study was therefore besides code assessment to demonstrate that simulations can be very beneficial for deep understanding of the plant response and further corrective measures. The abnormal event with reactor trip and safety injection signal actuation was simulated with the latest RELAP5/MOD3.3 Patch 05 best-estimate thermal hydraulic computer code. The measured and simulated data agree well considering the major plant system responses and operator actions. This suggests that the RELAP5 code simulation is good representative of the plant response and can complement not available information from plant measured data. In such a way, an event can be better understood.
Highlights
The integral effects facilities are scaled down and contain atypicalities; plant measured data are very important for code assessment
The influence of steam flow on the steam generator pressures is shown in Figures 11(c) and 11(d) and on the cold leg temperatures shown in Figures 12(a) and 12(b)
The abnormal event with loss of external load, followed by safety injection actuation and reactor trip has been simulated with the latest RELAP5/MOD3.3 Patch 05 best-estimate thermal hydraulic computer code
Summary
The integral effects facilities are scaled down and contain atypicalities; plant measured data are very important for code assessment. The plant measured data come mostly from startup tests and operational events. Several such tests and events have been analyzed in the past [1–. When an operational event occurred, not all plant data may be measured, which are important for interpretation of the events and physical understanding. For some measured parameters part of history may be missing. In such a case well-simulated transient progression can help in reconstructing the plant response. The purpose of this study was twofold: on one hand to assess the latest version of RELAP5/MOD3.3 Patch 05 and on the other hand to better understand the plant response to the event with the reactor trip and safety injection signal actuation.
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