Sensitivity Evaluation of AP1000 Nuclear Power Plant Best Estimation Model

Abstract

The best estimation process of AP1000 Nuclear Power Plant (NPP) requires proper selections of parameters and models so as to obtain the most accurate results compared with the actual design parameters. Therefore, it is necessary to identify and evaluate the influences of these parameters and modeling approaches quantitatively and qualitatively. Based on the best estimate thermalhydraulic system code RELAP5/MOD3.2, sensitivity analysis has been performed on core partition methods, parameters, and model selections in AP1000 Nuclear Power Plant, like the core channel number, pressurizer node number, feedwater temperature, and so forth. The results show that core channel number, core channel node number, and the pressurizer node number have apparent influences on the coolant temperature variation and pressure drop through the reactor. The feedwater temperature is a sensitive factor to the Steam Generator (SG) outlet temperature and the Steam Generator outlet pressure. In addition, the cross-flow model nearly has no effects on the coolant temperature variation and pressure drop in the reactor, in both the steady state and the loss of power transient. Furthermore, some fittest parameters with which the most accurate results could be obtained have been put forward for the nuclear system simulation.

Preliminary Assessment of Engineered Safety Features Against Station Blackout in Selected PWR Models

“…The other PWR model, a two-loop AP1000, is developed by the Westinghouse of USA, which classifies the auxiliary feedwater system as a non-safety related system due to the design of passive engineered safety features. The feedwater is supplied from the start-up feedwater system using only motor-driven feedwater pump powered by the emergency AC diesel generator and feedwater tank for 14 hours core cooling capacity [14]. The OPR-1000 of Korea is two-loop PWR, which also uses the typical turbine and motor-driven auxiliary feedwater pumps taking feedwater for storage tank and condensate storage tank as backup supply.…”

“…Other remaining selected PWR models such as CNP-1000, ACP-1000, and ACPR-1000 do not have passive engineered features for core cooling after shutdown. The AP-1000 otherwise is claimed by the US vendor as an advanced PWR design with passive safety, in which the passive residual heat removal system (PRHR) is installed as part of the passive core cooling system (PXS) [14]. The PRHRS is equipped with the PRHRS heat exchanger (PRHRS-HX), which is submerged in the in-containment refueling water storage tank (IRWST) and directly connected into the reactor vessel through an inlet line from one of primary system hot leg and an outlet line to the steam generator cold leg plenum as shown in Figure 4.…”

Uncertainty and sensitivity analysis of a PWR LOCA sequence using parametric and non-parametric methods

“…Moreover, the phenomena related to the sequence were identified through the LBLOCA PIRT, see [38,39]. Afterwards, and by means of the literature sensitivity analyses see [10,[40][41][42] the parameters and phenomena with a significant relevance were also selected. Finally, 25 uncertain parameters complete the set employed in the analyses.…”