Boiling water reactor plant shutdown

IE Information Notice 84-81, Inadvertent reduction in primary coolant inventory in boiling water reactors during shutdown and startup. (Multiple Plants). 

This report examines the severe accident sequences and radionuclide source terms at the Sizewell pressurised water reactor with a piestressed concrete containment, the Konvoi pressurized water reactor with a steel primary contaimnent, the European Pressurised water Reactor (EPR) and a boiling water reactor with a Mark 2 containment. The report concludes that the key accident sequences for European plant designs are transient events and small loss-of-coolant accidents, loss of cooling during shutdown, and containment bypass sequences. The most important chemical and transport phenomena are found to be revaporisation of volatile radionuclides from the reactor coolant system, iodine chemistry, and release paths through the plant. Additional research is recommended on release of fission products from the fuel, release of fission products from the reactor coolant system, ehemistry of iodine, and transport of radionuclide through plants. 

Plant operating experience has shown that pressurized water reactors and boiling water reactors are susceptible to a variety of abnormal events during shutdown conditions. 

The overall goals of the planned update of the section on low power and shutdown Level 1 PSA in (FAK 2005a) are to provide more precise terms and definitions with particular reference to the different phases of low power and shutdown states in German nuclear power plants (with Boiling Water Reactor (BWR) or Pressurized Water Reactor (PWR)) as well as an adaptation and clarification of the examples for the analyses provided in the document. 

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