BE puts back restart date for two AGRs

Monday, 13 October 2008

British Energy (BE) announced that although boiling closure unit (BCU) repairs at its Hartlepool and Heysham 1 nuclear power plants are "progressing well", two of the units will not return to service until early 2009.
 

The Heysham 1 plant (Image: BE)

The BCUs which have been causing problems are unique to the Hartlepool and the Heysham 1 sites. Advanced Gas-cooled Reactors (AGRs) have their eight boilers (steam generators) fitted inside the reactor's reinforced concrete containment structure. Wire windings in the BCUs form part of the pressure boundary. A broken wire winding was discovered on a BCU at Hartlepool unit 1 during a planned inspection in September 2007, and BE decided to take its sister units at Hartlepool and Heysham 1 out of service for inspection and assessment.
 

In a statement, BE said: "Good progress has been made across all four reactors on the engineering work required to return the BCUs to service. This includes installation of thermal shielding, cooling water systems, enhanced instrumentation systems and secondary restraint components."
 

The BCUs cannot be replaced, so BE is placing circumferential bands around the BCUs to 'lock in and enhance the existing pre-stress'. Regulatory approval to begin installation of circumferential bands was received on 21 August. However, BE reported that installation of the circumferential bands on the lead reactor (Heysham 1 unit 1) has taken longer than originally planned.
 

"We continue to target the return to service of all four reactors in the third quarter of this financial year 2008/09, however, the time required to install the circumferential bands means that is now likely that two reactors will not return to service until early 2009," BE said. All four reactors had previously been expected to resume operation by the end of 2008.
 

The company added, "As a result of the extent of work involved - nearly two million man hours to date - and the additional man hours involved in the installation of the modifications, we now expect that the costs in this financial year of commissioning and installing the engineering modifications will be marginally higher than the previous disclosed estimate of £115 million ($200 million)."
 

BE added that whilst the four reactors at Hartlepool and Heysham 1 have been offline due to the BCU issue, it has taken the opportunity to carry out work originally scheduled for future outages. This work has included the replacement of some 3 kilometres of cast iron cooling water pipe work at both plants.
 

The extended outages have not helped BE's generation figures at all. The company announced last week that its total output for the six months ended 28 September 2008 was 22.7 terawatt-hours (TWh), comprising 19.2 TWh from its nuclear power plants and 3.5 TWh from the 1960 MWe Eggborough coal-fired power plant. This compares to total output of 30.7 TWh during the same period in 2007, of which 27.8 TWh came from BE's nuclear plants and 2.9 TWh came from its coal plant.