The foundations are provided by isolated bases and strip footings with a designed maximum bearing pressure of 3 tons per square foot. The turbine house is a steel-framed, aluminium clad building 380 feet (120 m) long, 160 feet (49 m) wide and 90 feet (27 m) high, with a reinforced concrete basement 26 feet (7.9 m) deep. Both reactors were housed in a single building to achieve savings in building costs. The composite steel and reinforced concrete cap above each reactor is 12 feet (3.7 m) thick. The biological shields are 100 feet (30 m) high and vary between 10 and 14 feet (3.0 and 4.3 m) thick. The foundations for the reactors and associated boilers are provided by a reinforced concrete raft 8 feet (2.4 m) thick, founded on the sand with a designed net bearing pressure of 3.5 tons per square foot. The reactors and turbines were both supplied by English Electric. The steam produced by the boilers was fed to two turbo-generators each rated at 325 MW, but which operated at a reduced capacity of 250 MW from 1969. These supplied heat to eight boiler units, four associated with each reactor. The main plant consisted of two 1,010 MW (thermal) Magnox reactors, which were natural uranium, carbon dioxide gas cooled, graphite moderated units.
SATISFACTORY LAYOUT PLANNER FULL
At full load, 70 MWe were used in providing works power from the gross electrical output of 490 MWe. The total generating capacity was reduced to 490 MW in 1969, and then 420 MWe in 1973, to arrest the rate of oxidation of internal reactor-core components. In 1967 a second turbo-alternator was commissioned with a rating of 275 MW.
The power station originally had a single 324.75 MW turbo-alternator, and a gross generating capability of 327.7 MW.
The designed net electrical output of the station was 652 MWe. The station was officially opened on 7 April 1967 by the Lord Lieutenant of Suffolk, the Earl of Stradbroke. Unit 1 was commissioned on 21 March 1966, and Unit 2 on 15 September. During its 40-year operational lifetime, it had produced 110 TWh (400 PJ) of electricity, which would have been sufficient to meet the domestic needs of England and Wales for six months. The main construction contract was awarded to British Nuclear Design and Construction Ltd ('BNDC'), a consortium of English Electric, Babcock & Wilcox and Taylor Woodrow Construction, The initial budget was £56 million, but due to inflation this figure rose to £65 million.
The main contract was placed in November 1960 and construction work on Sizewell A began on 1 April 1961. The Midlands Project Group of the Central Electricity Generating Board (CEGB) planned and managed the project. A new branch line off the Leiston branch has been proposed for rail terminals for the construction of Sizewell C power station to the north of the existing B power station. The line is now only rarely used for transportation of spent fuels from Sizewell B since the completion of decommissioning of Sizewell A in 2006. The line was extended and used for the delivery of construction materials for Sizewell B power station in the 1980s. This is connected to the East Suffolk line via a south-facing junction to the north of Saxmundham station. Nuclear fuel was handled by a crane loading facility at the end of the 5-mile (8.0 km) Leiston/Sizewell branch railway. Sidings were installed at the railhead primarily to transport irradiated elements to the United Kingdom Atomic Energy Authority plant at Sellafield, Cumbria. The site is reached by road, with the nearest railhead about one mile inland at Sizewell Halt.