Objective 1. OBJECTIVES In the late phase of a severe water reactor accident, fission products deposited earlier on primary circuit surfaces may experience increasing temperatures by heal transfer from the surrounding gas or radiating corium or by their own decay heat. For some accident scenarios, a large fraction of the volatile species is predicted to deposit in the reactor coolant system early in the sequence. This fraction has the potential for release later in the sequence, perhaps at a time when the containment has failed and offers little attenuation to the source term. The extent to which the deposition results in permanent retention / removal from consideration is, therefore, a key issue. Safety assessments have highlighted the potential importance of revaporisation and addressing the uncertainties associated with revaporisation phenomena is now an internationally-recognised priority. The Phebus-FP experiments provide a unique opportunity to acquire realistic irradiated samples with which to study revaporisation by detailed analyses of samples generated from the Phebus FP programme together with supporting separate - effects studies and model developments. The project objective is to investigate the importance of revaporisation for the reactor source term, with the following experimental programme: A) - recover circuit portions from a number of l'hebus Fl' tests - characterise the initial state of the deposits - revaporise the deposits - measure the kinetics of the revaporisation - characterise the secondary deposits and the final state of the original deposits and hence characterise the physics and chemistry of the re-emission B) This will be supported by: - separate-effects tests to quantify the revaporisation phenomena and provide data from simple cases (both inactive and active simulated samples) to interpret the releases from the more complex l'hebus FP samples. - development of models, as well as pre-test calculations, which will, together with the separate effects data, facilitate interpretation and quantification as well as the transposition of data to the reactor case. With this additional information the timing and nature of the reactor source tern- release in an accident can be assessed. Programme(s) EAEC-NFS 2 - Specific research and training programme in the field of nuclear safety and safeguards, 1994-1998 Topic(s) 020301 - In-vessel fission product behaviour Call for proposal Data not available Funding Scheme CSC - Cost-sharing contracts Coordinator United Kingdom Atomic Energy Authority (UKAEA) EU contribution No data Address Winfrith Technology Centre DT2 8DH Dorchester United Kingdom See on map Total cost No data Participants (2) Sort alphabetically Sort by EU Contribution Expand all Collapse all COMMISSION OF THE EUROPEAN COMMUNITIES Germany EU contribution No data Address Hermann-von-Helmholtz Platz 1 76125 KARLSRUHE See on map Total cost No data N/A Finland EU contribution No data Address See on map Total cost No data