Hunterston B Nuclear Power Station - History

History

The construction of Hunterston B was undertaken by a consortium known as The Nuclear Power Group (TNPG). The two advanced gas-cooled reactors (AGR) were supplied by TNPG and the turbines by C. A. Parsons & Co. Hunterston B started generating electricity on 6 February 1976.

On 3 December 1977 The Times reported that seawater had entered the reactor through a modification of the secondary cooling system. The secondary cooling system uses fresh water to cool various items including the bearings of the gas circulators, which circulate the carbon dioxide (CO₂) coolant through the reactor to the boilers. A small leak of CO₂ through a seal had developed, and a bypass pipe was installed to remove the water contaminated with CO₂ to the seawater cooling ponds. When maintenance work was carried out on the reactor and the pressure in the gas cooling system was reduced, sea water was able to flow back up this bypass pipe and into the reactor. The residual heat of the reactor was such that the seawater evaporated rapidly, leaving deposits of salt in the reactor around the gas circuit. It was estimated at the time that the reactor could be out of operation for a year, that the repairs could cost £14 million, and that electricity tariffs would have to rise by between 1 and 2 per cent. Extensive modelling work was performed in the Nuclear Power Company's (NPC) Whetstone, Leicestershire, fluid flow laboratories to determine where the salt would have been deposited, and the salt was successfully removed by technicians using vacuum cleaners and the plant returned to operation.

In 2006 there was concern that the graphite moderator core in each of the twin AGRs at Hunterston B might have developed structural problems in the form of cracking of the bricks (as at similar AGRs) but this has not been confirmed.

Its net electrical output was 1,215 MW. In 2007 the reactors were restricted to operating at a reduced level of around 70% of full output (around 850 MWe net). Subsequent work during maintenance shutdowns have resulted in Reactor 3 operating at around 82% (540Mwe net) in early 2011, and Reactor 4 at around 73% (480 MWe net). In total this equates to around 1020MWe gross output from the generators. Internal load of 90MWe brings net output to approximately 930MWe. Hunterston B is capable of supplying the electricity needs of over 1 million homes.

Hunterston B was originally planned to operate until 2011. In 2007 planned operation was extended by 5 years to 2016. In December 2012 EDF said it could (technically and economically) operate until 2023.