ABSTRACT
The paper deals with the problem of probabilistic safety asaeeaement method (a brief presentation of the method, application at Shutdovn Cooling System at PHWR -CANDU 600 MW NPP) and PSA type knowledge utilisation for advisory systems for operational support.
The first part of the paper presents the PSA method, which is an important improvement of the earlier methods (the Canadian method of safety matrix -SUM – and the American method of probabilistic risk evaluation -PRA) and it is the first part of a vast PSA project, which will be realised in Romania under the direct supervision of the IAEA specialists.
The example in the paper refers to the TOP-EVENT, the Shutdovn Cooling System does not perform his function of the at removing from the core, after the reactor shutdown, in the normal operation mode, with full and pressurised primary circuit, (the heat removal presumes that in none of the core canals does not occur the boiling).
For this Shutdown Cooling System fault tree generation after defining the TOP-EVENT, we described the system, then its interface systems (which are 14), the fault tree (and the hypotheses used in its generation)
After the fault tree generation to the last allowen (by the available data) resolution level, we implemented the tree on the computer (using the PSA – PACK programmes), 804we reduced it to the minimal cut-sets (formed by the base events), permitting to obtain the first qualitative results). The tree will be developed in the future to the last possible resolution level»in order to make opportune a quantitative analyse.
Concerning the specific plant PSA type knowledge using in the Advisory Systems for Operational Support, we present some aspects of current status of these systems.
