Method and related computerised aids for the diagnosis and the prognosis of the plant status during an emergency on a PWR by the french protection and nuclear safety institute

IPSN (Institut de Protection et de Surete Nucleaire) in conjunction with EDF developed an approach intended to monitor the current status of a PWR during an accident and to project the progression of key phenomenological events. Intended for the off-site emergency teams, this methodology is implemented with dedicated manual and computerized tools. The diagnosis is based on the analysis of plant specific data. The information transmitted from the plant is organised in such way that the expert team assesses rapidly the status of the different safety barriers and functions. Specific tools are used to quantify certain parameters such as break size or activity within the containment. The prognosis is based on the assessment of the safety systems availability and on extrapolations to forecast the evolution of the accident (time to core uncover and core degradation, fission product release prognosis...). The use of the crisis tools allows the expert team to estimate strategy effectiveness and to structure the dialogue with the EDF analogous teams during emergency drills. Both method and software have been used for the last two years and are continuously improved