Nuclear decommissioning

Example of decommissioning work underway.

The reactor pressure vessel being transported away from the site, which will be buried. Images courtesy of the NRC.

The decommissioning of nuclear power plants is sometimes referred to as nuclear decommissioning, to mark the difference between 'conventional' decommissioning and dismantling projects. The main difference to the dismantling of a 'conventional' facility is the possible presence of radioactive or fissile material in a nuclear facility, that requires special precautions.

Generally speaking, nuclear plants were designed for a life of about 30 years. Newer plants are designed for a 40 to 60 year operating life.

Decommissioning involves many administrative and technical actions. It includes all clean-up of radioactivity and progressive demolition of the plant. Once a facility is decommissioned, there should no longer be any danger of a radioactive accident or to any persons visiting it. After a facility has been taken out of service it allows its release from regulatory control and relieves the licensee of his responsibility for its nuclear safety.

[edit] Decommissioning options

The International Atomic Energy Agency has defined three options for decommissioning, the definitions of which have been internationally adopted:

• Immediate Dismantling (or Early Site Release/Decon in the US): This option allows for the facility to be removed from regulatory control relatively soon after shutdown or termination of regulated activities. Usually, the final dismantling or decontamination activities begin within a few months or years, depending on the facility. Following removal from regulatory control, the site is then available for re-use.
• Safe Enclosure (or Safestor(e)): This option postpones the final removal of controls for a longer period, usually in the order of 40 to 60 years. The facility is placed into a safe storage configuration until the eventual dismantling and decontamination activities occur.
• Entombment: This option entails placing the facility into a condition that will allow the remaining on-site radioactive material to remain on-site without the requirement of ever removing it totally. This option usually involves reducing the size of the area where the radioactive material is located and then encasing the facility in a long-lived structure such as concrete, that will last for a period of time to ensure the remaining radioactivity is no longer of concern.

[edit] Experience

See also: List of nuclear reactors

A wide range of nuclear facilities has been decommissioned so far. This includes nuclear power plants (NPPs), research reactors, isotope production plants, particle accelerators, uranium mines etc. However, the number of decommissioned power plants is fairly small. There are companies specialized in nuclear decommissioning; the practice of decommissioning has turned into a profitable business. Decommissionning is very expensive; the current estimate by the United Kingdom's Nuclear Decommissioning Authority is that it will cost at least £70 billion to decommission the existing United Kingdom nuclear sites; this takes no account of what will happen in the future. Also, due to the latent radioactivity in the reactor core, the decommissioning of a reactor is a slow process which has to take place in stages; the plans of the Nuclear Decommissioning Authority for decommissioning reactors have an average 50 year time frame. The long time frame makes reliable cost estimates extremely difficult. Excessive cost overruns are not uncommon even for projects done in a much shorter time.

[edit] Legal aspects

The decommission of a nuclear reactor can only take place after the appropriate licence has been granted pursuant to the relevant legislation. As part of the licensing procedure various documents, reports and expert opinions have to be written and delivered to the competent authority, e.g. safety report, technical documents, environmental impact study (EIS).

In the European Union these documents are the basis for the environmental impact assessment (EIA) according to Council Directive 85/337/EEC. A precondition for granting such a licence is an opinion by the European Commission according to Article 37 of the Euratom Treaty. Article 37 obliges every Member State of the European Union to communicate certain data relating to the release of radioactive substances to the Commission. This information must reveal whether and if so what radiological impacts decommissioning – planned disposal and accidental release – will have on the environment, i.e. water, soil or airspace, of the EU Member States ^[1]. On the basis of these general data, the Commission must be in a position to assess the exposure of reference groups of the population in the nearest neighbouring states.

[edit] Cost of decommissioning

In USA many utilities estimates now average $325 million per reactor all-up (1998 $).

In France, decommissioning of Brennilis Nuclear Power Plant, a fairly small 70 MW power plant, already cost 480 millions euros (20x the estimate costs) and is still pending after 20 years. Despite the huge investments in securing the dismantlement, radioactive elements such as Plutonium, Cesium-137 and Cobalt-60 leaked out into the surrounding lake.^{[2] [3]}

In the UK, decommissioning of Windscale Advanced Cooled Reactor (WAGR), a 32 MW power plant, cost 117 millions euros.

In Germany, decommissioning of Niederaichbach nuclear power plant, a 100MW power plant, cost about 90 millions euros.

[edit] (Lack of) Decommissioning Funds

In Europe there is considerable concern on the funds necessary to finance final decommissioning. In many countries either the funds do not appear sufficient to pay the financial decommissioning, and in other countries the (substantial) funds are being used (too) freely for activities other then decommissioning, putting the funds at risk, and distorting competition with parties who do not have nuclear decommissioning funds available.^[4]

Currently (2008) the European Commission is looking into this issue.

[edit] See also

• Nuclear Decommissioning Authority
• Ship-Submarine recycling program
• Nuclear entombment
• Marcoule French nuclear site

[edit] References

[edit] External links

• decommissioning.info is a portal with information on nuclear decommissioning
• US Nuclear Regulatory Commission
• European website on decommissioning of nuclear installations
• Decommissioning Fund Methodologies for Nuclear Installations in the EU, rapport by the German Wuppertal Institute, commissioned by the European Commission. May 2007.