Local councils and emergency services have blocked a bid to halve the area of a nuclear emergency planning zone surrounding the Atomic Weapons Establishment (AWE) Aldermaston, despite a recommendation to scale down the zone by the government agency responsible for nuclear safety.
Despite proposals from AWE and the Office for Nuclear Regulation (ONR) to reduce the radius of the detailed emergency planning zone (DEPZ) around the Aldermaston nuclear weapon factory, the AWE Off-site Emergency Planning Group, which represents the emergency services and councils that would have to respond to any incident at AWE, agreed that the zone should not change because of concerns about the implications of the Fukushima crisis for nuclear emergency planning.
The decision has not been publicly announced by AWE, the Office for Nuclear Regulation, or West Berkshire Council, which is responsible for preparing an off-site emergency plan for AWE sites. Nuclear Information Service has obtained key documents giving the background to the decision following requests made under the Freedom of Information Act.
The detailed emergency planning zone defines the area around AWE sites where members of the public would be required to take shelter to protect themselves from the impact of a radiation emergency. The REPPIR emergency planning regulations, which outline the legal requirements for nuclear emergency planning, require the zone to cover the area within which a member of the public could expect to receive a radiation dose of 5mSv if an accidental release occurred.
During a regular three-yearly review of REPPIR arrangements, technical specialists based at AWE had calculated that the zone should be revised downwards from the 3km radius which was originally set in 2002 to a new radius of 2.125 km from the centre of the AWE Aldermaston site. After assessing AWE's submission, ONR agreed that the size of the zone should be reduced.
However, after a meeting with ONR and AWE on 18 July 2013, key members of the AWE Off-site Emergency Planning Group – West Berkshire, Basingstoke and Deane, and Hampshire County Councils with Thames Valley Police and the Royal Berkshire Fire and Rescue Service – decided to reject a recommendation to cut the size of the zone. The group expressed concerns that “some communities would be split by the proposed zone”, which “could lead to confusion”, and that “the full outcomes of the Fukushima incident have not been fully concluded”.
The group did not feel “that there is any immediate benefit” in reducing the size of the DEPZ but requested that the matter should be kept under review for the future.
ONR has written back to say that it accepts the “pragmatic approach” taken by the Group in balancing the benefits and issues that would arise from a reduction in the Detailed Emergency Planning Zone.
A study undertaken in 2012 by consulting engineers Large & Associates on behalf of Nuclear Information Service was highly critical of the process used to calculate the DEPZ radii for AWE sites in previous years.
In its latest REPPIR hazard identification and risk evaluation study, AWE has taken a new approach to calculating the size of the Aldermaston DEPZ, based on a 'reference accident' that assimes a seismic initiating event would result in a radiological release from two facilities simultaneously.
Despite the revised approach taken by AWE, a number of criticisms of the process were made by ONR in its assessment report. The regulator stated that the report included “a paucity of information on more important details” and that “it was not possible to trace the dose estimates back to vulnerable inventories based on the information presented”. It was “somewhat unclear” which nuclear inventories were considered to be invulnerable to release and the reasons for this.
ONR assessed AWE's risk evaluation as 'below standard' in three out of nine criteria used to judge the report, with only one criterion assessed as being better than “adequate”.
A summary version of the risk evaluation report has been published on the AWE website, although a detailed classified version, which is 300 pages long, has not been released.
ONR did not assess the hazard identification and risk evaluation report prepared by AWE for the AWE Burghfield site. Although the regulator has the power to request a site operator to provide further information to support its assessments, ONR instead took the view that there had been no change of circumstances at Burghfield. ONR has asked AWE to take a reference accident approach to dose calculations for Burghfield when documentation is prepared in the next three-year REPPIR review cycle.
If you would like to receive copies of the documents obtained under the Freedom of Information Act which are referred to in this article please email Nuclear Information Service.