Assessment of the consequences of aircraft crashes on a PWR power plant (as applied to Sizewell B)

The study analyses the probability of severe core damage and an uncontrolled release of radioactivity in the event of a postulated crash of a military combat aircraft on the central buildings of the proposed Sizewell-B pressurized water reactor. The study identifies a number of regional damage states which would arise as the result of such a crash. The probabilities of damage states are estimated on the basis of building geometries and resistance to impacts and the distribution of aircraft crash energies and angles in the vicinity of the site. For each regional damage state the surviving equipment is compared with the minimum requirements for reactor core control and from this comparison, probabilities of core damage are estimated using simple functional event trees. It is concluded that it is unreasonably pessimistic to assume that an aircraft crash onto Sizewell-B would lead inevitably to a core meltdown or uncontrolled release of radioactivity. (U.K.)