Publications Details
A review of the technical issues of air ingression during severe reactor accidents
Severe reactor accident scenarios involving air ingression into the reactor coolant system are described. Evidence from modem reactor accident analyses and from the accident at Three Mile Island show residual fuel will be present in the core region when air ingression is possible. This residual fuel can interact with the air. Exploratory calculations with the MELCOR code of station blackout accidents during shutdown conditions and during operations are used to examine clad oxidation by air and ruthenium release from fuel in air. Extensive ruthenium release is predicted when air ingression rates exceed about 10 moles/s. Past studies of air interactions with irradiated reactor fuel are reviewed. Effects air ingression may have on fission product release, transport, deposition and revaporization are discussed. Perhaps the most important effects of air ingression are expected to be enhanced release of ruthenium from the fuel and the formation of copious amounts of aerosol from uranium oxide vapors. Revaporization of iodine and tellurium retained in the reactor coolant system might be expected.