Opened in 1967, it had two
Magnox reactors producing 424megawatts (MWe) in total – enough electricity on a typical day to serve an urban area twice the size of
Bristol. Reactor 1 went critical on 18 September 1967 and first generated electricity on 9 November 1967. Reactor 2 started generating electricity in April 1968. The construction was undertaken by a
consortium known as The Nuclear Power Group ('TNPG'). The reactors were supplied by TNPG and the turbines by
AEI and
C. A. Parsons & Co. Oldbury was the first nuclear power station in the UK to use
prestressed concrete pressure vessels, earlier Magnox reactors having used steel pressure vessels more suited to smaller reactors. The design net power output of the station was 626
MWe, but due to steel corrosion problems from the hot
carbon dioxide coolant within the reactor,
operating temperature had to be reduced soon after operation started causing a large drop in power output. Initially, the power output was set at 424MWe, dropping to 400MWe by 1973. Then as remedial measures were adopted, power was progressively increased to 434MWe by 1983 with a gas outlet temperature of , compared to the design temperature, which was maintained as the normal operational output. The station had two 216MW turbo-alternator generators giving a gross electrical capability of 439.5MW and a net capability of 416MW. The steam conditions at the turbine stop valves was 43.0bar at . The generating capacity, electricity output, load factor and
thermal efficiency were as shown in the table. In 1976/77, Oldbury was presented with the Hinton Cup, the
CEGB's
"good house keeping trophy". The award was commissioned by
Sir Christopher Hinton, the first chairman of the CEGB. In 1992, Reactor one set a world record for the longest continuous period of power generation from a commercial nuclear reactor, of 713days 21hours and 32minutes.
Hinkley Point A Nuclear Power Station held the previous world record of 700days and 7hours, set in 1988. From 2005 until 2012, the power station was protected by armed officers from the
Civil Nuclear Constabulary. ==Closure and decommissioning==