Community Research and Development Information Service - CORDIS


There is a tendency to conceive advanced Pressurised Water Reactors (PWRs) as having a larger and deeper pressure vessel to mitigate core thermal response during anticipated accidents or abnormal events. This is, however, resisted by present Design Basis Accident (DBA) assumptions which would prescribe a reduction in the Primary Cooling System (PCS) volume. The latter would minimise mass and energy release and thus pressure and temperature build-up in the containment, following a severe Loss of Coolant Accident (LOCA) caused by a complete severance within the primary and secondary system pipework. The relaxation of the current DBA assumptions, which on the basis of the acquired experience and probabilistic risk assessment studies have been shown to be too conservative, could have a significant impact on the conceptual development of advanced PWRs. Specifically, the volumes of both the primary and secondary cooling systems could be optimised without close linkage to containment performance, providing enhanced safety margins with respect to primary thermal excursions. This is partially confirmed by LOCA experiments conducted in the LOBI Test Facility.

Additional information

Authors: ADDABBO C, JRC Ispra (IT)
Bibliographic Reference: Paper presented: IAEA TCM on Progress in Development and Design Aspects of Advanced Water-Cooled Reactors, Roma (IT), Sept. 9-12, 1991
Availability: Available from (1) as Paper EN 36404 ORA
Record Number: 199111455 / Last updated on: 1994-12-02
Original language: en
Available languages: en