The Dungeness nuclear power stations are a pair of non-operational nuclear power stations located on the Dungeness headland in the south of Kent, England.

Dungeness A is a legacy Magnox power station consisting of two 250 MWe reactors which were connected to the National Grid in 1965 and reached its end of life in 2006.

Dungeness B is an advanced gas-cooled reactor (AGR) power station consisting of two 520 MWe reactors, which began operation in 1983 and 1985. They were the first in a series of AGR reactors to be constructed across the UK. In March 2009, unexpected problems discovered during a maintenance shutdown on unit B21 resulted in the reactor remaining offline for nearly 18 months. In 2015, the plant received upgrades and was given a second ten-year life extension to 2028. In September 2018, as both units were shut down for a scheduled maintenance outage, EDF encountered "significant and ongoing technical challenges" which ultimately led to the announcement of its closure on 7 June 2021.

Quick Facts Country, Location ...

Dungeness A Nuclear Power Station
Dungeness A
Country	England
Location	Kent, South East England
Coordinates	50.9132°N 0.9641°E / 50.9132; 0.9641
Status	Decommissioning in progress
Commission date	1965
Decommission date	2006
Owner(s)	Nuclear Decommissioning Authority
Operator(s)	Magnox Ltd
Nuclear power station
Reactor type	Magnox
Reactor supplier	The Nuclear Power Group
Thermal power station
Primary fuel	Nuclear
Cooling source	Sea water
Power generation
Units operational	4 × 142.5 MW
Units decommissioned	2 × 219 MWe net
Nameplate capacity	500 MWe
Annual net output	See graph in text
External links
Website	www.magnoxsites.co.uk/site/dungeness-a/
Commons	Related media on Commons
[edit on Wikidata] grid reference TR0832016959

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Dungeness A is a legacy Magnox power station that was connected to the National Grid in 1965 and has reached the end of its life. It possessed two nuclear reactors producing 219 MW of electricity each, with a total capacity of 438 MW.^[1] The construction was undertaken by a consortium known as the Nuclear Power Group ('TNPG').^[2] The reactors were supplied by TNPG and the turbines by C. A. Parsons & Co.^[1] There were originally four × 142.5 MW turbo-alternators, these were later down-rated to 106 MW machines.^[3] Steam pressure and temperature at the turbine stop valves was 535 psi (36.9 bar) and 391 °C (736 °F).^[3]

Electricity output

Electricity output from Dungeness A power station over the period 1966-84 was as follows.^[3]

Dungeness A annual electricity output GWh.

Graphs are unavailable due to technical issues. There is more info on Phabricator and on MediaWiki.org.

Nuclear fuel for Dungeness power stations can be delivered and removed via a crane loading facility at the end of the 9-mile (14 km) Appledore-Lydd-Dungeness branch railway. This is connected to the Ashford to Hastings line via an east-facing junction located to the west of Appledore station. The close proximity of the Appledore-Lydd-Dungeness branch to the nuclear power stations allow for a more direct route to and from major fuel fabrication sites all whilst minimising the use of road convoys thus lowering traffic impact on nearby communities.^[4]

Dungeness B is an advanced gas-cooled reactor (AGR) power station consisting of two 1,496 MWt reactors, which began operation in 1983 and 1985 respectively. Dungeness B was the first commercial scale AGR power station to be constructed. Its design was based on the much smaller Windscale AGR prototype, the WAGR. The £89 million contract was awarded in August 1965 to Atomic Power Construction ('APC'),^[10] a consortium backed by Crompton Parkinson, Fairey Engineering, International Combustion and Richardsons Westgarth.^[2] The completion date was set as 1970.

During construction, many problems were encountered in scaling up the WAGR design. Problems with the construction of the pressure vessel liner had distorted it, so that the boilers, which were to fit in an annular space between the reactor and the pressure vessel, could not be installed, and the liner had to be partially dismantled and rebuilt. This work cost about £200,000, but there was a huge cost of financing an extra 18 unproductive months for a power station costing around £100 million, of which 60% was already complete.^[11] Serious problems were also discovered with the design of the boilers, which had to withstand the pounding of hot carbon dioxide (CO₂), pressurised to 600 pounds per square inch (4,100 kPa) and pumped around the reactor coolant circuit by massive gas circulators. As a consequence, the casings, hangers and tube supports all had to be redesigned. The cost of the modifications, and financing during the delays, caused severe financial pressures for the consortium and its backers, and in 1969 APC collapsed into administration.

The CEGB took over project management, imposed light penalties in order not to cripple Fairey and International Combustion, and appointed British Nuclear Design and Construction (BNDC) as main contractor. In 1971, problems with corrosion of mild steel components in the first generation Magnox reactors gave the designers cause for concern. The Dungeness B restraint couplings - mechanical linkages that held the graphite core in place whilst allowing it to expand and contract in response to temperature changes - were made of mild steel and could be subject to the same corrosion. It was decided to replace them with components made from a new material.^[12] In 1972, problems were found with the galvanised wire that was used to attach thermocouples to stainless steel boiler tubes. During heat treatment of the tubes at temperatures up to 1,050 °C (1,920 °F), the galvanising zinc diffused into the tubes and made them brittle. The cost had by then risen to £170 million.^[13] By 1975, the CEGB was reporting that the power station would not be completed until 1977 and that its cost had risen to £280 million.^[14] By 1979, the cost had risen further to £410 million.^[15]

Reactor 1 first generated power on 3 April 1983, 13 years behind schedule and at a cost of £685 million, four times the initial estimate in inflation-adjusted terms.^[16] The original construction consortium had collapsed.^[17]

As with the "A" station, the turbines were built by C.A. Parsons & Company^[1] and the station has two 660 MWe turbo-alternator sets, producing a maximum output of 1,320 MWe,^[8] though net output is 1,090 MWe after the effects of house load, and downrating the reactor output due to corrosion and vibration concerns.^[18]

In 2005, the station's closure date was extended from 2008 by ten years, which would allow it to continue operating until 2018, 35 years after first power generation.^[19]

In March 2009, serious problems were found when Unit 21 was shut down for maintenance, and the reactor remained out of action for almost 18 months.^[20][21] On 24 November 2009, a small fire in the boiler annexe of Unit 22 caused the second reactor to be shut down as well. Subsequently, Unit 22 has been intermittently shut down for up to several months at a time. Unit 21 was restarted in August 2010.^[22][23][24] Unplanned shutdowns continued into 2011,^[25][26] with 21 down for repairs from November 2011 to March 2012.^[27]

In 2015, the plant was given another ten-year life extension, allowing an upgrade to control room computer systems and improved flood defences, taking the accounting closure date to 2028.^[28]

On 15 April 2009, Dungeness was included in a list of 11 potential sites for new nuclear power stations, at the request of EDF Energy, which owns and operates Dungeness B.^[40] The government did not include Dungeness C in its draft National Policy Statement published on 9 November 2009, citing environmental reasons and concerns about coastal erosion and associated flood risk.^[41] The site was ruled out by Secretary of State for Energy and Climate Change Chris Huhne in October 2010, with the former government's list of eleven potential sites reduced to eight.^[42] Despite these environmental concerns, local Conservative MP Damian Collins, supported by some residents, lobbied Parliament to reconsider that position.^[43][44]

From 1961 to 1984, Dungeness power station also housed the mercury arc valves of the static inverter plant converting AC into DC for transmission on HVDC Cross-Channel, the high-voltage direct current power cable carrying electric power across the English Channel to France. In 1983, a more powerful new inverter at Sellindge replaced this facility.

Both stations were originally built, owned, and operated by the CEGB. Following privatisation of the electricity supply industry and the later part-privatisation of the nuclear power generating industry they are now owned by two different bodies: the original Magnox station Dungeness A by the non-departmental government body the NDA and newer AGR Dungeness B by EDF Energy.

The stations are built on a large area of open shingle, measuring 12 by 6 kilometres (7.5 by 3.7 mi), which has been deposited by the sea and built up over thousands of years. The entire area is moving slowly north and east as the sea moves the shingle from one side of the headland to the other. It is surrounded by a nature reserve Site of Special Scientific Interest (SSSI). A fleet of lorries is used to continuously maintain shingle sea defences for the plant as coastal erosion would otherwise move shingle away at an estimated rate of 6 metres (20 ft) per year. Around 30,000 cubic metres (39,000 cu yd) of shingle are moved each year. It seems that deposition on the north shore of the headland does not keep pace with erosion, although the power stations are about 1 kilometre (0.62 mi) to the west of that shore. In all, 90,000 cubic metres (120,000 cu yd) are moved each year along parts of the coast between Pett Level and Hythe. This is necessary for the safety of the entire area including the power stations. During operation, around 100 million litres (22×10^⁶ imp gal) of cooling water was extracted and returned to the sea each hour, after being heated by 12 °C (22 °F).

The headland and the coastline between Pett Level and Hythe are volatile. In recorded history Walland Marsh to the west of the power stations has been flooded.^[45] In the space of sixty years severe inundation occurred, temporarily bringing the sea inland to Appledore and the original mouth of the River Rother from north of the headland at Romney to the south at Rye Harbour. The site is a few metres above Mean Sea Level and would be isolated in the event of flooding of the magnitude that submerged large areas of East Anglia and the Netherlands in 1953. It has been conjectured^[who?] that the Great Storm of 1987 did not bring the sea to the stations because there was a low tide at the time. Climate change could cause more frequent and powerful storms, and associated waves and surges are possible though not probable, and might increase the instability of the headland.^[45]

• Nuclear power in the United Kingdom
• Energy policy of the United Kingdom
• Energy use and conservation in the United Kingdom