The site of Sellafield is the principal complex of the nuclear die British. Initially named “ Windscale ”, it was renamed Sellafield following a serious accident in one of its nuclear plants. Located on the coast of the Irish Sea in the county of Cumbrie at the North-West of the England, it includes/understands today 400 buildings distributed out of 10 km ² and employs approximately 10000 people. This site shelters several factories:
- a first factory of reprocessing open of 1951 to 1964, the unit B204
- an engine of the type graphite broken gas in 1957 and his/her twin brother, the piles Windscale
- an engine of reprocessing of fuel of the engines Magnox, the unit B205
- one second factory of reprocessing of fuels and storage of highly radioactive waste, open in 1985, implied in the accident of 2005, the unit B570 Thorp .
- the open factory Sellafield Mox (SMP) Seedling in 1997 to produce Combustible MOX,
- the four engines Magnox of Calder Hall which are definitively stopped in 2003,
- of other military vocation factories.
Origin
The first two factories on the site were built in 1940 to manufacture explosives, before the site is not selected like nuclear production site in 1947. The site was selected to provide the British raw material of the weapons nuclear, the Plutonium. It starts with the construction of B204 in 1947, then B205 in 1964. With the passing of years, other factories will come to be added to it, like the Windscale piles for the production of military plutonium of use in 1952, a power station of 200 MW in 1956, surfaces of storage for the Nuclear waste which accumulate, etc
Notable units
The name of the units of Sellafield are officially named according to the concatenation of the letter B and a number.
SIXEP - Site Effluent Ion-Exchange Seedling
SETP - Effluent Segregated Treatment Seedling
WAGR - Windscale Advanced Gas-cooled Reactor
The Windscale piles
The experimentation of the first fuel loading in the Windscale piles took place in July 1950, this loading reprocessed by B204 as from July 1952 to separate plutonium from it from uranium.Contrary to the first American engines of Hanford moderated with the Graphite and cooled by water, the Windscale piles are made of a metal uranium heart moderated with the graphite and cooled by air. Each engine contains practically 2000 tons of graphite.
A fire in 1957 involves their closing.
Calder Hall
Calder Hall is oldest Nuclear plant of production of electricity in the world. It is equipped with 4 engines Magnox each one having a production capacity of 50 MW.See also: Nuclear plant of Calder Hall/Sellafield
B6 unit - Pile 1 Chimneys
B16 unit - Pile 2 Chimneys
B29 unit - fuel storage lays
B30 unit - swimming pool
Large swimming pool open of storage of fuel Magnox irradiated and known for its bad condition. It makes approximately 20 Mr. broad, 150 Mr. length and 6 Mr. of depth. Birds come to be posed on its surface, carrying with have a little its radioactivity. It was used of 1960 to 1986. A wall of containment is envisaged in order to limit the consequences of a rupture of the basin in the event of earthquake. It must be emptied of its waste and dismantled in the years to come.It is impossible to determine with precision the quantities of stored matters, the algae developing in water make very difficult the visual monitoring of the basin and the British authorities could not provide precise accounting to the inspectors of Euratom. The European commission consequently continued Great Britain before the European Court of justice. There would be approximately 1,3 tons of plutonium, including 400 kg in the form of mud at the bottom.
It would also contain waste coming from the Japanese nuclear plant Tokai Walled.
This unit is the greatest concern of the British Autorité of nuclear dismantling in Great Britain, because of sound very important radiation level. Radiations are so important by place which it is not possible for a person to remain there more than two minutes, from where the difficulty of its dismantling or its control. The basin is not even tight, time fissuring the concrete and the cold the contractor, making it possible radioactive water to escape. What is worth to him the nickname of Dirty thirty , " salt trente" in English.
B243 unit
B277 unit - fuel seedling manufacture
B355 unit
Unit B570 - Thorp
Thorp, for Thermal Oxide Reprocessing Seedling, is a factory of nuclear reprocessing of irradiated fuel. Built between 1978 and 1994, it was operational in August 1997.It is conceived to reprocess British but so foreign fuels. The selected process is not the same one as for B205,
B572 unit
B701 unit
Nuclear accidents
The complex of Windscale/Sellafield was place of several nuclear accidents, in particular in 1957 and in April 2005. He is regarded as the site more Radioactif of Western Europe.
Accident of 1957
The accident occurs in one of the engines graphite gas with natural uranium of the site. At the time of an operation of maintenance of graphite, a fire occurs and lasts several days, during which fission products, primarily 740 téra-becquerels (740 thousand billion becquerels) of iodine 131, are rejected outside. The radioactive cloud traverses then England, carried by the winds, then touches the continent without the population not being informed. The accident of Windscale is classified on level 5 on the international scales of the nuclear events (INNATE). See List of the nuclear accidents of civil exploitation of the years 1950.After this accident, Windscale is débaptisé and becomes Sellafield.
Accident of 2005
The April 19th 2005, 83.000 Liter S of radioactive matter were discovered in a part in Reinforced concrete (conceived in order to collect the escapes) with the reprocessing plant of Thorp following an escape in a drain. Being given the quantity of 200 kg plutonium presents, there was a high risk of release of a Accident of criticality.The investigation showed that probably made 9 months that the escape had started: an inconsistency between the quantity and the weight of matter entering and outgoing of the system of treatment having been noted for the first time in August 2004, but was not transmitted to the suitable manager. Thereafter, the increase in the Temperature and the discovery of radioactive Liquide in the Puisard indicated also a problem, but that was ignored. Épanchement was formally detected only after another To that the which suggested that matter missed, leading the operators at the end of a few days to send a Caméra Robot ized on the defective drain in order to measure the Volume liquid in the sump.
Factory THORP was closed until July 2007 when one of the tanks was given in service, with recommendations of the authority of safety. A ratio of 28 pages was published and put on line, concluding the investigation required by the British authority of safety (HSE/ND). The responsible managers were sanctioned. An internal audit was made by the company BNFL which pled guilty at the time of its lawsuit and has to pay three imposed fines on October 16th, 2006 by the royal court of Carlisle, for non-observance of three authorizations respectively relating to the “Sûreté, the mechanisms, apparatuses and circuits”, the “effective instructions” and the “escapes and losses of radioactive materials or radioactive waste” (either on the whole 500.000 £ of fines more approximately 68.000 £ of procedures).
Quelques 19 ton S of Uranium and 160 Kilogram S of Plutonium (on 200 kg according to the IRSN) dissolved in nitric Acid were pumped sump in a tank out of the closed factory from now on of Thorp. The radiation levels in the tank prevents very entered of human and the repair of the escape by a robot would be too difficult. The persons in charge plan a diversion in order to avoid the tank to continue the exploitation. According to the owner level of criticality could not have been reached during time when the solution was presents to the bottom of the building sheltering the tanks.
According to the French experts of IRSN, it seems that a " excess of confiance" in the design of the factory and that a culture of insufficient safety are at the origin of these défaillances." They classified this accident with the “ level 3 ” of the scale INNATE. French side, following this experience feedback and to two " losses of étanchéité" occurred in 1997 in ex-factory UP2-400 and in 2001 in its factory UP2-800, AREVA has to update in its factory of La Hague (factories UP3 and UP2-800) its procedures of safety. As private individuals of the periodic visual monitorings will be made to avoid the risk of the escapes of radioactive material pulverulent, or liquid and likely to crystallize or evaporate because of a strong ventilation, a wall or a hot substrate or a rather vast surface of spreading out so that the solution can evaporate; these types of escapes not being necessarily detected by the systems located in bottom of léchefritte or sump. In October 2007, the INRS specified that means of video monitoring and measuring devices neutronics were added to the existing device.
Sources
- the fire of 1957 and one documentary video which explains the role of the factory and the circumstances of the accident, dissident-media.org.
- Windscale: The escape of 1973, the site more the pollutant of Europe, dissident-media.org.
References
See too
See also: Nuclear plant of Calder Hall/Sellafield, List of the nuclear reactors
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