Preliminary Analysis of an Aged RPV Subjected to Station Blackout

Abstract

Today, 46% of operating Nuclear Power Plants (NPP) have a lifetime between 31 and 40 years, while 19% have been in operation for more than 40 years. Long Term Operation (LTO) is an urgent requirement for all of the nuclear industry. The aim of this study is to assess the performance of a reactor pressure vessel (RPV) subjected to a station blackout (SBO) event. Alterations suffered by the material properties and creep at elevated temperatures are considered. In this study, coupling between MELCOR and Finite Element Method (FEM) codes is carried out. In the Finite Element (FE) model, the combined effects of ageing and creep are implemented through degraded material properties and a viscoplastic model. The reliability of the model is validated by comparing the FOREVER/C1 experimental results. The results show that the RPV lower head bends downwards with a maximum radial expansion of about 260 mm and RPV thermomechanical properties are reduced by more than 50% at high temperatures. The effects of ageing, creep and long heat-up strongly affect the resistance of the RPV system until the point of compromising it in the absence of/delayed emergency intervention. Aged RPV at end-of-life may collapse earlier, and in less time, with the same accidental conditions.

A Comparative Assessment of Conventional and Artificial Neural Networks Methods for Electricity Outage Forecasting

“…The results demonstrated a good agreement between the theoretical and experimental results. Such a predictive model will help in the application of operational management programs [26]. Watson et al presented a weather ensemble impact outage model that is able to predict the potential impacts of thunderstorms, such as the location of storm impacts and the total damage by an event using weather variables, WRF (Weather Research and Forecasting Model) simulation and NOAA (National Oceanic and Atmospheric Administration) analysis data sets.…”