The investigation into the exact cause of the liquid leak at the Doel nuclear reactor will take weeks, or even months, Federal Agency for Nuclear Control (FANC) chief Frank Hardeman told the Belgian Chamber’s sub-commission on nuclear safety on Wednesday. Since the fault is located in a place that is difficult to reach, the reactor first has to be fully emptied. The defective conduit then has to be sent to a laboratory.
The reactor’s operator, Electrabel, detected the leak in the nuclear part of Unit 1 of the Doel reactor at about 06.00 a.m on the 23rd of April last. Operations at the reactor were stopped immediately, but Electrabel was not able to locate the leak right away. The reactor therefore had to be cooled so that the system could be thoroughly examined.
Using an endoscope, Electrabel was finally able to locate the leak on the 26th of April. The fault was in the soldering of a conduit in one of the reactor’s primary cooling systems, which pump additional water when there is an emergency.
According to the FANC, the water (some 6,000 litres) that escaped from the conduit was collected without it reaching the outside, and no workers were harmed. The FANC ranked the situation caused by the leak at Doel 1 in the lowest category of the international radiation hazard scale. However, Hardeman admitted that the situation was “exceptional” and “abnormal”.
Doel 2 also functions with this type of conduit, but the cause of the problem at Doel 1 will need to be ascertained before the possibility of a similar problem developing there can be assessed. That could take “weeks, even months, more” since the reactor must first be completely emptied. Once all fuel has been withdrawn from it, it will then be possible to take out the faulty part and send it to a laboratory.
Hardeman said he intended to have the investigation cover much more than faulty soldering. The FANC has already asked for an inspection of the identical circuits of Doel 1 and Doel 2.
Doel 1, in activity since 1975 and the oldest nuclear reactor in Belgium, will remain inactive at least until early October, even if only for the purposes of major maintenance that should have started in May but has now been brought forward.
The extra time will be used to resolve any other problems identified in the primary circuit. The FANC will determine when the reactor can be restarted.
Under current plans, the reactor is to remain in operation until 2025.