6 SIZEWELL A & B NUCLEAR POWER STATIONS, LEISTON

6.1 The Premises

Sizewell A and Sizewell B Nuclear Power Stations are licensed under the Nuclear Installations Act 1965 and are required to conform to the Radiation Emergency Preparedness and Public Information Regulations 2001.Sizewell A ceased generating electricity in late 2006 and is currently undergoing defuelling and de-commissioning.Sizewell B generates electricity for supply to the ‘National Grid’ using one water-cooled nuclear reactor of the ‘PWR’ design. The station was commissioned in 1995 and currently has a 35-year operational lifetime

6.2 The Substances

The primary risk arises from radioactive fuel rods used on site for power generation.Other hazardous substances held on site and used for the routine operations include:

• Hydrocarbon fuels and lubricating oils for the operation of steam raising boilers, gas turbines and generators for on-site power and thermal heat generation;• Bulk chemicals including concentrated acids and alkalis, and also gaseous / liquid hydrogen stocks;• Small quantities of specialist chemicals and gases;• Significant quantities of carbon dioxide gas (on the A station only) used as the primary reactor coolant medium. Large stocks of non-radioactive carbon dioxide are stored on site.

6.3 The Risks

The main risk to the public relates to harmful exposure to radioactive substances carried in a gaseous discharge plume, which has been released from the site. This release of gaseous and particulate radioactive substances is likely to be a result of a breach in the primary cooling system of the affected nuclear reactor and may be associated with leaks from the nuclear fuel located in the reactor.

A radioactive substance of particular concern is Iodine-131, which may be discharged as a gas in the plume. This substance can be readily absorbed by the human body and concentrates in the thyroid, resulting in radiation doses to the exposed individual.

Such an event is likely to result in the need to consider urgent countermeasures to protect the public outside the site security fence from a radiological hazard.

In relation to the other hazardous substances, risks may arise from fire, resulting in an atmospheric release of non-radioactive substances from the stations, or chemical spillage, which may contaminate the marine environment or potable water supplies.

Sizewell A & B Power StationsHealth Premises within a 2 mile radius

Sizewell A & B Power StationsHealth Premises within a 2 mile radius (close

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