JRC develops new reactor safety code
The Institute for Systems, Informatics and Safety of the European Commission's Joint Research Centre, in conjunction with the relevant national laboratories, have developed a new reactor safety code for calculating fuel/coolant interactions in case of severe accidents. Accidents such as these, where the fuel elements might be degraded and melted, are very unlikely but have to be guarded against because of the potential risk of a release of radioactivity. The code has already been tested on the JRC's test facility FARO (Fuel melting and release oven) where a series of high pressure melt quenching tests, using up to 150kg of molten corium, were successfully concluded. Important results were obtained on fuel coolant interactions in severe accident scenarios for Light Water Reactors (LWR). Of particular importance was the fact that all the tests showed considerable melt break-up and quenching in water. The tests also showed that the mean debris size ranged from 3.5 to 5 mm, showing that the debris bed could therefore be cooled by water. In addition, the early thermal load to debris collecting structures was found to be mild and steam explosions did not occur.