Forsmark 1 and 2 precautions

[Forsmark, SKI, 5 February; Nordpool, 7 February] Inspections have identified reduced elasticity in the rubber seal between the 'wet' and 'dry' wells at Forsmark 1. Management decided to shut the unit down to investigate further on 2 February. As a precaution, the identical Forsmark 2 was also shut down on 3 February. The wet well contains cool water, into which steam from the core cooling system can be piped during reactor overpressure situations, providing an additional means of heat removal from the reactor system. The seal is relatively large (40-50 m long) and sited between fixed components of the overall reactor building, making it difficult to replace. The well system could operate satisfactorily with minor leaks, although major ones would have a certain effect on performance. Neither Forsmark nor the Swedish Nuclear Power Inspectorate (SKI) reported that the seal would not function correctly, but Forsmark management have decided to replace the seal at unit 1. Carrying out this "big job" would mean the unit would restart in one month at the earliest. Inspections proved unit 2's seal was satisfactory and the reactor will restart on 10 February.