The Late Phase Source Term Phenomena (Shared Cost Action) project started on 1 February 2000, with a duration of 36 months. Its aim was to quantify fission product and core materials released from molten corium. This work was concerned with examining the kinetics of release of the key fission products, lanthanides and actinides (as simulants), and to allow the importance of other phenomena, such as sparging, slag formation, two-phase systems). A series of experiments was also conducted to aid with understanding the chemistry of species released during the late phase of an accident, with particular emphasis on ruthenium behaviour. Tests aimed at examining the behaviour of a solidified core immersed in a water pool were also carried out. The results from these experiments were used to test and develop generic code models for the relevant phenomena. The models and experimental results were also used in plant calculations for Eastern, Western and advanced reactor designs. The results of the programme aid in the development of severe accident management strategies and provide data on fission-product behaviour in the late phase of an accident. The main achievements of the project are the provision of data on metallic and oxidic melts, the behaviour of ruthenium species formed under late-phase conditions and the behaviour of immersed corium melts, the testing and development of models for late-phase phenomena, and plant assessments for Eastern European and new reactor designs.
(1) : AEA Technology, Winfrith, UK
(2) : LSK, St Petersburg, Russian Republic
(3) : RUB/NES, Bochum, Germany
(4) : Framatome ANP, Erlangen, Germany
(5) : IPSN, CE Cadarache, France
(6) : NRI Rez, Prague, Czech Republic