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Sellafield (formerly known as Windscale)
is a nuclear processing and former electricity generating site, close to the village of Seascale on the coast of the Irish Sea in Cumbria, England. The site is served by Sellafield railway station.
Sellafield was previously owned and operated by British Nuclear Fuels plc (BNFL), but is now operated by Sellafield Ltd and, since 1 April 2005, has been owned by the Nuclear Decommissioning Authority.
In 2008 the Nuclear Decommissioning Authority contracted the management of Sellafield Ltd to Nuclear Management Partners, a consortium of US company URS, British company AMEC, and AREVA of France. The initial contract is for five years, with extension options to 17 years.[1]
Facilities at the site include the THORP nuclear fuel reprocessing plant and the Magnox nuclear fuel reprocessing plant. It is also the site of the remains of Calder Hall, the world's first commercial nuclear power station, now being decommissioned, as well as some other older nuclear facilities.[2]
In 1981 the name of the site was changed back from Windscale to Sellafield, possibly in an attempt by the United Kingdom Atomic Energy Authority to disassociate the site from recent press reports about its safety.
The Windscale Piles
Calder Hall nuclear power station
Windscale Advanced Gas Cooled Reactor (WAGR)
Magnox reprocessing plant
Thermal Oxide Reprocessing Plant
2005 Thorp plant leak
Highly Active Liquor Evaporation and Storage (HALES)
Windscale Vitrification Plant (WVP)
Sellafield MOX Plant
Radioactive waste stores
Fellside Power Station
© More in the WIKIPEDIA !
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Memory of Sellafield leak rekindled
Radioactive discharges into Irish Sea in 1970s still monitored; reassurances in Japan similar
By WILLIAM HOLLINGWORTH
LONDON — The release of radioactive materials into the Pacific from the stricken Fukushima No. 1 nuclear plant is being closely monitored by scientists still observing the consequences of a similar incident in Britain more than 36 years ago.
The mid-1970s saw a sharp increase in radioactive matter enter the Irish Sea following problems at the Sellafield nuclear reprocessing facility in northwest England.
Although the releases were authorized, they resulted in a rise of radioactive cesium-137 and iodine-131 in the Irish Sea and the after-effects are still being monitored in the area today.
Scientists claim inquiries have concluded there is no evidence the discharges have adversely affected the health of the local population, but critics of the nuclear industry have cast doubt on these assertions.
Experts in Britain are now turning their attention to the stricken Fukushima plant, which has, until early April, been leaking highly radioactive materials into the sea due to a crack in the structure. In addition, a large volume of low-level waste was deliberately dumped into the ocean to assist the cleanup process.
Bill Camplin, group manager for radiological and chemical risk at the Center for Environment, Fisheries and Aquaculture Science (Cefas), in Lowestoft, said the two incidents are "not grossly dissimilar" in terms of the concentrations reported in the water.
Although Sellafield has been releasing waste into the sea since 1952, the potency of the discharges shot up in the mid-1970s.
Spent fuel rods stored in cooling ponds started to corrode, leading to a significant spike in the radioactive waste flushed out to sea.
As Camplin explained in an interview, at its peak in 1975, Sellafield pumped out 5,000 terabecquerels of cesium-137. By contrast, current discharges are now around 10 terabecquerels per year.
The contamination resulted in seafood caught within 10 km of Sellafield containing "several thousand" becquerels per kilogram of cesium-137. The corresponding seawater concentration around Sellafield was 100 becquerels per liter of cesium-137.
The figures for Fukushima bear some similarities, with water concentrations at about 50 becquerels per liter for cesium-137, and 100 becquerels per liter for iodine-131 in an area 10 km from the release point, according to data supplied to Camplin via the International Atomic Energy Agency in the earlier stages of the crisis. However, the IAEA notes decreasing trends following the plugging of the leak at Fukushima.
Camplin and his team at Cefas agree with the Japanese government's advice not to consume seafood caught close to the Fukushima plant.
In Britain, the authorities would generally intervene when the concentration of cesium-137 reached 1,000 becquerels per kg of seafood and Camplin noted some of the measurements in shellfish caught off Fukushima have been much less than that threshold.
In the 1970s, the British authorities did not impose any restrictions on the consumption of seafood in the Irish Sea despite similar levels.
But, as John Hunt, a consultant to Cefas, explained, "The maximum dose to regular shellfish consumers around Sellafield peaked at 2 millisieverts per year during the mid-1970s. That is more than the current annual dose recommended by the International Commission on Radiological Protection of 1 millisievert, but back then the annual maximum dose was 5 millisieverts. And we are not aware of any health implications as a result of that."
After the spike in radiation, bosses at Sellafield worked hard to bring down the levels.
However, the effects are still present in the sea, particularly in relation to cesium-137, which takes a lot longer to decay than iodine and tends to find its way into the seabed and onto beaches.
Camplin said that if the Japanese authorities haven't done so already, they should be warning people not to spend much time on the beaches near to the plant, as there could be quite high levels of radiation there.
But the good news is the iodine-131 should start to dissipate from the ocean quite rapidly.
Camplin and Hunt both appeared to be satisfied with how the Japanese authorities are coping, but would like to see more marine data and are currently liaising with colleagues in Japan.
Camplin said, "I'm not saying that it hasn't been done, but I would like to see more continuous monitoring. It needs to take into account different radionuclides, marine material and cover a greater area.
"Various institutes are talking about having a collaborative research program into Fukushima. I will expect work to move on to how the ecosystem is reacting to these radioactive inputs."
A millisievert is a measure of the dose of radiation a person can receive. The becquerel is a unit that measures radioactivity and 1 terabecquerel equals 1 trillion becquerels.
source : Japan Times, April 23, 2011 .
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Japan’s seas may not be long-term threat
By Simeon Bennett /April 22, 2011
RADIATION from fish and lobsters near Sellafield suggest radioactive material dumped into the sea from Japan’s Fukushima Dai-Ichi plant isn’t a long-term health threat, scientists said.
The Sellafield nuclear waste plant in Cumbria has discharged about 44 times more Cesium-137, one of the most harmful radioactive materials to humans, into the Irish Sea since 1952 than what has leaked from the Japanese plant this month, based on data from both sites. Still, average radiation doses by seafood consumers near Sellafield over 15 years have been half the recommended limit, studies show.
The research suggests bans on Japanese seafood are unnecessary, said Richard Wakeford, professor of epidemiology at the University of Manchester’s Dalton Nuclear Institute.
The US and EU have curbed imports from Japan, and some hotels have stopped serving seafood from the country because of radiation fears.
"It is not a long-term problem, and that’s what you learn from Sellafield," Mr Wakeford said. "I don’t think there’s any need for this knee-jerk reaction, which is hitting someone when they’re down."
Some 4,700 terabecquerel of radiation leaked from the plant into the sea between April 1-6, Junichi Matsumoto, general manager at plant operator Tokyo Electric Power Co, said.
That is 31,333 times more than what the utility said it dumped into the sea from April 5. The leak included 940 terabecquerel of Cesium-137, which takes 30 years to decay by half and can cause cancer if ingested.
Between 1952 and 2009, Sellafield legally discharged about 41,353 terabecquerel of Cesium-137, based on data from Britain’s Environment Agency and the Journal of Radiological Protection.
The biggest discharge in a single year was 5,200 terabecquerel in 1975.
The highest radiation doses were found in the 1970s among consumers of fish and shellfish in Cumbria.
The average dose in that group was as much as three millisieverts a year, according to a study published in 2000, triple the annual limit of one millisievert for man-made exposures set by the International Commission on Radiological Protection. The group’s average dose between 1995-2009 was 0.5 millisievert, data showed.
"Although it was fairly high levels being discharged, that initial discharge has stopped," said Tony Irwin, a nuclear technology lecturer at the Australian National University, who helped review practices at Russian reactors after the world’s worst nuclear disaster at Chernobyl in 1986.
People are exposed to an average of 2.4 millisieverts a year from the earth’s crust and cosmic rays, the World Nuclear Association in London states. Exposure of 100 millisieverts a year is the lowest level at which any increase in cancer is evident.
A becquerel is a measure of radioactivity and a terabecquerel is one trillion becquerel. A millisievert is a measure of the dose of radiation received by a person.
Japan plans to measure the radiation exposure of 150,000 residents near the Fukushima plant, the Yomiuri newspaper reported, citing Welfare Minister Ritsuo Hosokawa.
Contamination of the land within 100 kilometres of the plant is likely to have a greater long-term effect on human health than radiation in seawaters, said Peter Burns, former chairman of the United Nations Scientific Committee on the Effects of Atomic Radiation.
"The only significant pathway at this stage is the contamination that’s on the ground, and people getting external radiation from living in the contaminated area," Mr Burns said.
source : www.examiner.ie/ireland
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