Sidings were installed at the railhead primarily to transport irradiated elements to the United Kingdom Atomic Energy Authority plant at Sellafield, Cumbria.

[3] In March 1958 East Suffolk County Council selected the Sizewell site from shortlist to be earmarked for a nuclear power station,[4] and in September the Central Electricity Generating Board announced it would apply for consent to build one there.

[6] They received two objections (from the headmaster of Sizewell Hall girls school who feared pupils would be subject to "annoying remarks" from workmen,[7] and from Ipswich Natural History Society).

[12] 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.

[14] 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.

[15] The main plant consisted of two 1,010 MW (thermal) Magnox reactors,[15] which were natural uranium, carbon dioxide gas cooled, graphite moderated units.

[16] 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.

[18] On 7 January 2007, a contractor working on the decommissioning of the station noticed water leaking on to the floor of the laundry where he was washing his clothes.

It is estimated that up to 40,000 imperial gallons (180,000 L; 48,000 US gal) of radioactive water had leaked from a 15-foot (4.6 m) split in a pipe, with some spilling into the North Sea.

According to the HM Nuclear Installation Inspectorate's report of the incident, without the chance intervention of the contractor, the pond could have drained before the next scheduled plant inspection.

[24] However, a government official is cited stating that "it probably will be extended", while EDF intends to take a final decision on the estimated investment of £500-£700 million in 2024.

So that orders could be given to UK manufacturers, and to avoid project risk in dealing with what were at the time newly designed very large turbo-alternator sets, Sizewell B uses two full-speed, 3,000 RPM (50 Hz), nominal 660 MW turbo-alternator sets similar to those used at the AGR power stations Hinkley Point B, Heysham 1, Hartlepool and Torness, and at some fossil-fuel power stations elsewhere, but adapted to cope with the wetter steam conditions produced by the PWR steam supply system.

[27] The major components were supplied by:[28] A distinctive white hemisphere envelopes the outer shell of the twin-walled containment building that protects the pressurised water reactor and its steam generators.

[35] Before construction commenced, the design of Sizewell B was subjected to a detailed safety review by the NII, and a lengthy public inquiry.

The chairman of the inquiry, Sir Frank Layfield, reported in early 1987 that, subject to a satisfactory safety case, there were no substantive reasons why the project should not proceed.

The Nuclear Installations Inspectorate accepted the Pre-Construction Safety Case and issued a licence to proceed with construction in August 1987.

[39] On 17 March 2010, Sizewell B was taken offline for an extended period because of high moisture levels in the containment building due to a pressuriser electrical heater fault, requiring difficult repairs.

Numerous emergency services were called to the scene and the fire was brought under control by 3:30 the following day when the charcoal adsorber was flooded.

In 2013, a new remote Emergency Response Centre was inaugurated near the power station, following recommendations made after the Fukushima Daiichi nuclear disaster.

[47] Since the sale of British Energy to Électricité de France (EDF) in February 2009, plans for a further twin-unit reactor to be built at Sizewell have looked increasingly likely.

[48] On 18 October 2010, the British government announced that Sizewell was one of the eight sites which it considered suitable for future nuclear power stations.

It also called for lessons to be drawn from Hinkley Point C as well as the UK's offshore wind programme to ensure a timely procurement schedule.

CGN is owned by the Chinese government and has been blacklisted by the US Department of Commerce for attempting to acquire advanced US nuclear technology and material for diversion to military use.

The plant will largely replicate Hinkley Point C design to reuse experience, lower cost and ensure high levels of safety.

[63] In March 2022, it was announced that the UK government and EDF would each take a 20% stake in the project, with infrastructure investors and pension funds expected to take up the remaining 60%.