The federal minister for the environment, nature protection and reactor safety, Jürgen Trittin, has prevented Hesse state regulators from issuing a licence to backfit the sump opening of Biblis A with a grid box to enlarge the area available.
Trittin said that the Hesse Ministry for Environmental Rural and Consumer Affairs (Hmulv) had not informed his ministry that, without reinforcement work, the sump would not have withstood the weight of the reactor coolant water during rupture of a primary circuit pipe. Hmulv had asserted that the design basis for the 1225MWe PWR assumed a small leak in coolant piping, and not a larger break. It was therefore not necessary to determine whether the sump filter would withstand a so-called 2-F break. Operators RWE announced it would now reinforce the concrete cover for the sump strainer and expects the plant to be restarted in the autumn.
During a maintenance outage in April, Biblis A was ordered to be shut indefinitely after the discovery that the prime opening cross-section of the sump strainer was too small. Operators RWE filed an application to upgrade the strainer but Trittin raised concerns about how the strainer would perform during a loss of coolant accident, claiming that the safety examination carried out by Hmulv was not sufficient (see NEI August 2003, p6).