Trisha Shetty

AVR reactor

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Country  Germany
Capacity factor  50.0%
Opened  19 May 1969
Construction began  1961
Units decommissioned  1 x 15 MW
Average generation  65.7 GWh
Closed  31 December 1988
Decommission date  31 December 1988
AVR reactor httpsuploadwikimediaorgwikipediacommonsthu
Similar  Rheinsberg Nuclear Power Pl, Greifswald Nuclear Power Pl, Philippsburg Nuclear Power Pl, Stendal Nuclear Power Pl, SNR‑300

The AVR reactor (German: Arbeitsgemeinschaft Versuchsreaktor) was a prototype pebble bed reactor. It was located immediately adjacent to Jülich Research Centre in West Germany. Construction began in 1960, first grid connection was in 1967 and operation ceased in 1988. It was 15MWe, 46 MWt, and was used to develop and test a wide variety of fuels and machinery over its lifetime.

Contents

The AVR was based on the concept of a "Daniels pile" by Farrington Daniels, the inventor of pebble bed reactors. Rudolf Schulten is commonly recognized as the intellectual father of the reactor.

A consortium of 15 community electric companies owned and operated the plant. Over the life of the reactor there were many mishaps and accidents, causing some critics to call it a "shipwreck." During 2011-2014, outside experts examined the historical operations and operational dangers. Their final report in 2014 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.

The decommissioning of the AVR has been exceptionally difficult, time-consuming and expensive. Since the original operators were overwhelmed by the effort, government agencies have taken over dismantling and disposal. In 2003 they officially took ownership of the reactor and its nuclear waste. Since 2009 the temporary storage of 152 casks of spent fuel has been a controversy. The approval expired in 2013, because safety and stress tests could not be sufficiently proven; a permanent solution has not been reached. Due to the extremely high disposal expenses, since 2012 plans have been considered to export the casks to the United States. In 2014 a massive concrete wall to protect against terrorist plane crashes is to be built. On July 2, 2014 the Federal Environment ministry issued an evacuation order for the temporary storage.

AVR was the basis of the technology licensed to China to build HTR-10.

History

In 1959 the 'Association of Experimental Reactor GmbH' (AVR Ltd) was established by 15 municipal electric companies. Its purpose was to demonstrate the feasibility and viability of a gas-cooled, graphite-moderated high temperature reactor. BBC and Krupp began building the AVR in 1961. The planning and construction, led by Rudolf Schulten, was performed on almost purely industrial basis until 1964. Financial assistance was provided by the federal government, supported by Leo Brandt. In 1964 Schulten became Director of the Jülich Research Centre and it started to devote more attention to the pebble bed reactor. In 1966, AVR first achieved criticality, and it was connected to the national power grid in 1967. Information on construction costs vary between 85 and 125 million Deutsche marks ($2.5 - $3.7bn in 2014). The AVR GmbH remained formally independent until 2003, but was de facto dependant on JRC as of around 1970. JRC paid high operating grants to the AVR GmbH in order to ensure continued operation, since the electricity generated only covered a small part of the operating costs. In the mid-1970s revenue per year was about 3 million DM, against operating and fuel disposal costs of 11 million DM. JRC also supported the AVR through procurement and the disposal of fuel; JRC was and is owner of AVR fuel. In addition, the AVR operation was scientifically monitored by JRC.

In the first years the AVR was nominally operated with cooling gas outlet temperatures of 650 °C - 850 °C. In February 1974 the cooling gas outlet temperature was raised to 950 °C. These final high temperatures reached a world record for nuclear facilities, but werely later exceeded by the US test reactor UHTREX. Such high temperatures were supposed to demonstrate the suitability of the AVR for coal gasification, and thus contribute to longer-term plans for coal in Nordrhein Westfalen.

Contamination

Its Helium outlet temperature was 950 °C, but fuel temperature instabilities occurred during operation with locally far too 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. Some contamination was also found in soil/groundwater under the reactor, as the German government confirmed in February, 2010. Thus the reactor vessel was filled in 2008 with light concrete in order to fix the radioactive dust and in 2012 the reactor vessel of 2100 metric tons will be transported about 200 meters by air-cushion sled and seven cranes to an intermediate storage.

Proposed dismantling

There exists currently no dismantling method for the AVR vessel, but it is planned to develop some procedure during the next 60 years and to start with vessel dismantling at the end of the century. In the meantime, after transport of the AVR vessel into the intermediate storage, the reactor buildings will be dismantled and soil and groundwater will be decontaminated. Fuel removal out of AVR was difficult and lasted 4 years. During this procedure it became obvious that the AVR bottom reflector was broken; in its crack about 200 fuel pebbles remain captured. AVR dismantling costs will exceed its construction costs by far.

Report

In April 2014 a report of independent experts on the AVR operation was published. This report lists hidden or downplayed events and accidents and discusses an illegal manipulation of the reactor safety system during an accident. As a consequence of the report Juelich Research Center regretted failures and scientific misbehavior with respect to the AVR.

References

AVR reactor Wikipedia


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