A few years ago, a number of people, including IRSN staff were involved in Phenomena Identification and Ranking Tables (PIRTs) procedures organised by USNRC, see e.g. . They have appreciated the interest of such a method as an efficient way both for identifying the important pending issues in the field of reactor safety and for selecting the future research programmes on a reliable basis. This is especially important for an optimal use of the resources when the overall severe accident research budget is declining. According to such an experience, IRSN established contacts in Europe and overseas, with a view to prepare a methodology similar to that of a PIRT’s procedure on topics related to severe accidents, especially regarding In-vessel degradation, fission product release, transport processes and behaviour in the containment. At the same time, CEA was looking for an extension of the European group EUROCORE activities , devoted to core corium recovery after vessel, failure of which the methods were rather comparable to the PIRT’s ones. Besides, both via national initiatives and CEE programmes , Europe is today a central platform for ongoing severe accident research and expertise in terms of code developments, separate effects and integral experimental programmes.
Given this common interest for severe accident issues, the existence of comparable methodologies in complementary fields of expertise and the European context, IRSN and CEA jointly decided to submit a concerted action project for the 5th European Frame-Work Programme (FP5). A preliminary version of the proposal was circulated among several organisations - utilities, research centres, safety authority supports and the EC Joint Research Centres in order to collect suggestions and to build a finalised project. This one involves nineteen organisations from ten countries, several utilities from Europe (EDF, TVO, VEIKEI), vendor (Framatome ANP), regulatory bodies and their supports (IRSN, HSE, GRS, US-NRC, CSN,) and research centres (CEA, FZK, RIT, JRC, PSI, IKE, CIEMAT, UPM, AEAT). The project was approved and funded by the 5th FP as a two-year long concerted action under the name EURSAFE.The EURSAFE project is organised in five work packages (WP). The first one, WP1, is the co-ordination activities which are performed jointly by IRSN and CEA. The second package WP2 is the PIRTs itself. We will consider this point in details later on in this paper. WP3 is called -PIRT’s implications. It will take place after completion of the PIRT’s procedure. Its objective is to identify the needs in terms of future severe accident R&D programmes in the fields of code developments, separate effect experiments and integral tests, using as inputs the PIRT’s conclusions regarding important pending issues. The fourth work package WP4 should be a proposal of an optimised arrangement of European laboratories -a network of excellence- to perform these R&D programmes taking advantage of complementary competencies in both experimental and analytical areas, including operational experimental facilities, analytical tool and manpower. Finally, the fifth work package addresses the problem of finding a possible unified data conservation system for both existing and future severe accident experimental data which would ease the exchange of information and contributes to optimise the use of the resources. EURSAFE PIRT’s work includes three different activities. The first one is to identify severe accident phenomena. The second and third ones are the Safety oriented and Phenomena oriented ranking procedures. First, experts are requested to select from the list of phenomena those they consider as important from a reactor safety point of view. Then, for each of the selected items, they have to provide an estimate of the level of available knowledge. At the end, the phenomena having both a large impact on reactor safety and a rather low level of understanding are highlighted and will be potential candidates for additional R&D efforts. The PIRT’s work was followed by PIRT’s implications (WP3) work package. Its objectives were to define future R&D needs in terms of objectives and priorities, then to identify the required R&D tasks in terms of experimental programmes and codes and, finally, to review the European facilities and codes which could be used for these tasks, taking into account the existing and planned national programmes.