Severe accident risk reduction by containment leakage testing during operation

It was decided in Belgium in 1986 to reduce the frequency of the type A leakage tests of the containment and to perform annual low pressure leakage tests during reactor operation. These tests require special care if a good sensitivity and thus a high probability of detecting pre-existing openings is to be achieved. The experience so far has been very satisfactory. The literature shows that probability of pre-existing openings is relatively high. Containment leakage tests performed during reactor operation can significantly increase the probability of detecting pre-existing openings, and therefore reduce the risk of severe accidents. (orig.)