Probabilistic safety assessment of reactor unit 3 in the Paluel Nuclear Power Centre

A Probabilistic Safety Assessment (PSA) was conducted over a period of four years dating from 1986, on the French Nuclear Power Centre (NPC) of PALUEL. This NPC comprises four PWR power plants each with an output of 1300 MWe, commissioned between 1983 and 1987. Reactor unit No. 3 was chosen for this study. This NPC is the first in a 1300 MWe standardized series following on the 900 MWe standardized series represented by some forty reactors commissioned over the period 1976-1989. The purpose of a Probabilistic Safety Assessment on a nuclear reactor is to identify all the possible accident scenarios that might damage the reactor and to evaluate their frequency. These accident scenarios, or accident sequences, are identified by engineers using appropriate methods; they are generally a series of system failures and/or human operator errors, as is often the case in real-life accidents. The accidents concerned are those which might seriously damage the nuclear reactor - in particular the reactor core - and entail the release of radioactive products to the environment if the accident is not kept under control. In order to assess the probability of occurrence of these scenarios, their frequency is calculated by means of methods based on the theory of probabilities. Elementary data, such as the frequency of events initiating the accident, the frequency of equipment breakdowns, their time of repair or the frequency of human errors are deduced as much as possible from the analysis of feedback from experience on other nuclear plants. This document is a summary of the overall report on the Probabilistic Safety Assessment on a 1300 MWe PWR Power Plant (EPS-1300). Like the later report, it presents the results and knowledge gained from this study as of May 31, 1990. Additional analyses concerning a loss of coolant accident during shutdown of the reactor for maintenance outages are currently under way, and their conclusions will be incorporated in an updated version of the study if necessary. In any case, the study will be revised at a later data to reflect the progress in experience of PWR plants in service and new knowledge gained from operating studies