8.1 The Sizewell design

The UK s most recent reactor construction project was Sizewell B, a twin-unit pressurised-water reactor (PWR) based on Westinghouse s standard nuclear unit power plant system (Snupps). Sizewell B was ordered in 1987 and construction was completed in 1995, but when the reactor was ordered several other reactors based on the Snupps design were already in operation in the USA. The design dates back more than 20 years and is very unlikely to be employed again, especially as new designs offer better efficiency (and hence economics) and generally produce much less spent fuel and other radioactive waste over their lifetime. No other designs have been licensed in the UK and so far the licensing agency, the Nuclear Safety Directorate (part of the Health and Safety Executive) says that it has not been asked to begin formal examination of any designs.

If the decision was taken to go ahead with a new reactor or series of reactors in the UK, there are several designs that are clear front runners. The industry is at pains to point out that these are evolutionary designs, based on familiar designs that have been in operation for up to 30 years in several countries. But while they are based on the same fundamental principles as existing pressurised-water reactors, boiling-water reactors, CANDUs and high-temperature reactors, the designs have been re-examined from the ground up. The aim is to increase safety and efficiency by simplifying the designs, while retaining all the necessary safety systems and ensuring...