Office for Nuclear Regulation

Third quarter 2009 statement of nuclear incidents at nuclear installations

A statement on incidents at nuclear installations in Britain which meet Ministerial reporting criteria is reported to the Secretary of State for the Department of Energy and Climate Change and the Secretary of State for Scotland and is published every quarter by the Health and Safety Executive.

For the period 1 July 2009 to 30 September 2009 there was one incident at a civil licensed nuclear installation that is confirmed as meeting the reporting criteria. However there is also one other event that may be reportable. An update on this event will be provided in the next report.

The events meeting the criteria in the Quarter 1 July to 30 September 2009 was:

Sellafield Ltd

Sellafield Ltd (SL) reported the detection of contamination on B212, a plant that stores radioactive liquors arising from reprocessing activities on the site. The amount of radioactivity is in excess of column 4 schedule 8 of the Ionising Radiation Regulations 1999 which means that the incident meets the reporting criteria.

There was no personal radiation exposure or contamination although one person received contamination to his clothing.

NII is investigating the incident but access problems and high radiation fields have hampered this. As a result, NII has not yet reached any firm conclusions as to the source of the contamination and the likely time that the contamination has existed. However, the initial indications are that the contamination is linked to the plants ventilation system.

NII will continue its investigation to determine the cause of the contamination and to decide whether enforcement action is warranted.

There were two incidents that we said in the last report may meet the reporting criteria during the previous quarter 1 April to 30 June 2009. An update on these is below.

Sellafield Ltd

Contamination identified on and around redundant ductwork from B209 to the ventilation fans at the base of B230 stack in the B229 compound. Further information leads to the judgement that this event does meet the Ministerial reporting criteria.

The extent of activity released as a result of this incident is still being determined by the licensee. Physical constraints in the area of the leak have meant that excavation of the contaminated material has had to be carefully planned and a significant amount of preparatory work undertaken, which has only recently been completed. This has led to a delay in the licensee completing its final assessment of the activity involved. However, Sellafield Ltd had done a preliminary assessment from surface contamination levels, which has given an initial estimate of alpha activity of approximately 1.5 MBq of fixed and loose contamination (which is 150% of the notification quantities specified in Column 4, Schedule 8 of the IRRs, thus satisfying the criteria for Ministerial reporting.)

Improved access has now enabled further samples to be taken and once analysed, these will be added to the existing assessment. Both NII and EA will be provided with the complete spillage assessment when it is available. The details of the final contamination assessment will then be used to inform any future regulatory enforcement decision.

Sellafield Ltd had confirmed the B209 duct work as the source of the contamination. The licensee is carrying out optioneering studies to look at engineering improvements to prevent a similar leak occurring in the future. NII is satisfied that the arrangements that the licensee has put in place in the interim will prevent any immediate reoccurrence.

Sellafield Ltd

Contaminated Wound Event during PCM Decommissioning Operations: 28/5/2009.

The dose levels were below those specified in IRRs 1999, and therefore, this event does not require to be reported to the Minister. However, it is my judgement that it may be of interest.

During decommissioning operations in B277, an operator working in an air-fed suit was using an angle grinder to size reduce equipment that was heavily contaminated with plutonium, and he received a wound on his thumb from the angle grinder. It is not clear how this happened. However, the operator was wearing the expected personal protective equipment for doing such work.

Sellafield Limited took prompt medical action to deal with the plutonium in the wound. This included excising the wound. The medical action was very effective and as a result, the dose to the operator was within limits specified in the Ionising Radiations Regulations 1999.

When the incident occurred, Sellafield Ltd was in the process of taking steps to respond to an Improvement Notice that was issued following a previous wounding incident from a different cause in the same plant.

There is a relatively high risk of what would be seemingly minor injuries occurring during the carrying out size reduction operations. But as they involve Plutonium, the consequences to the affected operator can be serious. Sellafield Limited uses similar methods for the decommissioning of plutonium contaminated plant to other UK licensees and, foreign nuclear plant operators. Size reduction is carried out to fit waste into a 200 litre drum, and this is the core process for decommissioning redundant plutonium facilities. The incident of 28 May 2009 reinforced our concern that the need to produce a standard waste form was overriding the consideration of safety of the operators.

Sellafield Ltd has responded positively, and we are working with Sellafield Ltd on the issue of the balance between waste form and operational safety. We have considered the HSE's Enforcement Management Model and concluded that Sellafield Limited is taking appropriate steps as a result of the previous Improvement Notice and that there would be no benefit from taking further regulatory actions.

Single copies of statements are available free from the Health and Safety Executive, Nuclear Directorate, Division 4, Building 4.N2, Redgrave Court, Merton Road, Bootle, L20 7HS,