Go-ahead for Tricastin fix

Thursday, 23 October 2008

Electricité de France (EdF) has been given permission to go ahead with a new plan to dislodge two fuel assemblies that became stuck during the refuelling of the Tricastin 2 reactor. The assemblies have been stuck since 8 September.

 

The reactor core remains under several metres of water during refuelling, when fuel assemblies are lifted out using a hoist. This is one of the reactors at South Texas Project in the USA (Image: STP)

The five-metre-long nuclear fuel assemblies were being handled remotely within the pressurized water reactor during a regular refuelling operation when they became stuck against some of the reactor's upper internal structures, themselves about four metres high. The assemblies have stayed in their stuck position ever since, cooled by the normal systems that maintain safety during the refuelling operation.

 

The Nuclear Safety Authority (Autorité De Sûreté Nucléaire, ASN) granted EdF permission for a procedure to dislodge the assemblies yesterday by way of a letter. The safety regulator did so after attending a demonstration of the method conducted at an Areva maintenance training facility at Chalon-sur-Saone. ASN said it was particularly interested to ensure the fuel assemblies could not fall back into the reactor core, and was convinced the technique EdF is planning is satisfactory.

 

An earlier plan to dislodge the assemblies had to be cancelled when an error was found in the safety case, Platts reported. Verification checks on an Areva-designed tool being installed to free the assemblies revealed a discrepancy between the item's actual dimensions and those described to regulators in the operation's safety case. This meant the safety case had to be revised, resubmitted and checked again, causing a delay.

 

EdF may now go ahead with the procedure when ready. France employs nuclear energy to produce nearly 80% of electricity, and EdF has extra nuclear capacity to make up for any temporary shortfall in generation. However, the company would be keen to complete the refuelling operation and bring the 915 MWe nuclear power reactor back into operation quickly.