22 Oct (NucNet): British Energy (BE) has shut down two reactor units and delayed the restart of another two after a planned inspection at Hartlepool-A1 in northern England revealed a problem related to a wire winding.
BE said the 595-megawatt Hartlepool-A1 gas-cooled reactor, which is currently undergoing a statutory outage, had been scheduled for restart early next month.
The company added that because this issue might have implications for sister gas-cooled units at Hartlepool and the Heysham A plant, also in northern England, it has taken “a conservative decision” to take two of these units (Hartlepool-A2 and Heysham-A1) out of service for assessment and inspection.
A fourth unit, Heysham-A2, is undergoing a refuelling outage but BE confirmed its return to service will also be delayed.
BE said the design of these boiler closure units is unique to Hartlepool and Heysham A nuclear power plants, which each have two units.
The company said it is assessing return to service dates for the units. “In determining these dates, British Energy will consider the potential to integrate any additional inspection work arising from our assessment within planned outages over the balance of the year,” a statement said.
In fiscal year 2006-2007, unplanned outages at BE’s Hunterston B and Hinkley Point B nuclear power plants resulted in 9.4 terawatt hours (TWh) of losses and were the main reason for a reduction in the company’s nuclear output for that period.
In 2006, BE found boiler tube cracking during a planned outage at Hunterston-B1 and a subsequent inspection at Hinkley Point-B1 indicated boiler tube cracking “at the high end of the range previously experienced”. All four Hunterston B and Hinkley Point B units were shut down throughout the rest of the year.
There are eight boiler closure units (BCUs) in each of the affected BE reactor units. The BCU is a steel and concrete structure forming part of the reactor pressure boundary. Each BCU is pre-stressed with nine layers of wire windings that are wound around its periphery.
