Hunterston B Nuclear Power Plant is a nuclear power station in North Ayrshire, Scotland. It is located about 9 km south of Largs and about 4 km north-west of West Kilbride. It is operated by EDF Energy. It currently generates up to 1000 MW and is due to operate until 2016.

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

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 75% (460Mwe net) in early 2011, and Reactor 4 at around 71% (430 MWe net). In total this equates to around 980MWe gross (output from the generators based on 90MW internal load) and is capable of supplying the electricity needs of over 1 million homes.

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.

Hunterston B Nuclear Power Plant is currently scheduled to be decommissioned in 2016.

The graphite moderator core in each of the twin advanced gas-cooled reactors (AGR) at Hunterston B has recently developed structural problems in the form of cracking of the bricks.
Hunterston B nuclear power plant
Official name Hunterston B
Country Scotland
Locale North Ayrshire
Construction began 1968
Commission date 1976
Owner(s) EDF Energy
Operator(s) EDF Energy

Reactor information
Reactors operational 2 x 1,500MWth (but see note)
Reactor type(s) AGR
Reactor supplier(s) TNPG

Power station information
Primary fuel Nuclear

Power generation information
Installed capacity 1,320MWe