History
In 1959, 15 municipal electric companies established the 'Association of Experimental Reactor GmbH' (AVR Ltd) to demonstrate the feasibility and viability of a gas-cooled, graphite-moderated high temperature reactor. In 1961,Fuels tested
From 1974 to 1978, mainly carbide BISO fuel was in the core. From 1983 to 1988, oxide fuel withHigher temperatures
During its initial years (1967-1973) the AVR was nominally operated with cooling gas outlet temperatures of . In February 1974, the cooling gas outlet temperature was raised to 950 °C. These final high temperatures were aDesign
The core held about 100,000 fuel element pebbles. Each contained about 1g of U-235. On average each would take 6 to 8 months to pass through the core. Helium flowed up through the core of pebbles.Contamination, internal and external
AVR's helium outlet temperature was 950 °C, but fuel temperature instabilities occurred during operation with localised exceedingly high temperatures. As a consequence the whole reactor vessel became heavily contaminated by Cs-137 and Sr-90. Concerning beta-contamination AVR is the highest contaminated nuclear installation worldwide as AVR management confirmed 2001. Thus in 2008, the reactor vessel was filled with light concrete to fixate the radioactive fine particule dust. In 2012, the reactor vessel of 2100 metric tons was to be transported about 200 meters by air-cushion sled and seven cranes to an intermediate storage site. During a severe water accident in 1978, Sr-90 leaked, and in 1999 soil and groundwater contamination below the reactor was discovered, as confirmed by the German government in February 2010.R. MoormanDecommissioning
Fuel removal out of AVR was difficult and lasted four years. During this time it became obvious that the AVR bottom reflector was broken; about 200 fuel pebbles remain wedged in its crack. Currently no dismantling method for the AVR vessel exists. It is planned to develop some procedure during the next 60 years and to start with vessel dismantling at the end of the 21st century. After the AVR vessel is moved into intermediate storage, the reactor buildings will be dismantled, and soil and groundwater will be decontaminated. Costs from 1988 to present are €700 million. The total AVR decommissioning costs are expected to be in the order of €1.5 to 2.5 billion, all public funds, i.e. to exceed its construction costs by far.Independent expert review report, 2014
From 2011 to 2014, outside experts examined the historical operations and operational hazards and in April 2014, published a report on the AVR operation. The report listed hidden or downplayed events and accidents and described serious concealed problems and wrongdoings. For example, in 1978 operators bypassed reactor shutdown controls to delay an emergency shutdown during an accident for six days. In 2014 the JRC and AVR publicly admitted to failures and issued a regret about its failures and scientific misconduct with respect to the AVR.Forschungszentrum JülicSee also
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