A statement on incidents at nuclear installations in Britain and during the transport of radioactive material, which meet Ministerial Reporting Criteria (MRC), is provided to the Secretary of State for the Department of Energy and Climate Change and the Secretary of State for Scotland, and is published each quarter by the Office for Nuclear Regulation.
For the period, 01 October 2014 to 31 December 2014, there were no incidents which met the MRC. The statement also includes an incident relating to the previous quarter (01 July 2014 to 31 October 2014). This has been included, as a result of further investigation, which produced updated information.
(Ministerial Reporting Criterion - Abnormal occurrences leading to a release or suspected release or spread of radioactivity, on or off site, which requires special action or special investigation by the operator)
In July 2013 the licensee dispatched eight redundant pond heat exchangers to Siempelkamp in Germany (via Winfrith) for disposal. In September 2014 Siempelkamp began cutting up the heat exchangers for smelting; as they did so, approximately 500 litres of very lightly contaminated water (left over from flushing the heat exchangers) was released, contaminating Siempelkamp personnel (though not to the extent that any limits were breached or even approached). The water was contained within a designated area. Sizewell A was made aware of the event on 25 September 2014. The incident was a non-compliance with the Carriage of Dangerous Goods regulations and also with licence condition 34, dealing with leakage and escape of radioactive waste.
The licensee's investigation has concluded that the root cause of the event was that the passage of crucial information was reliant on verbal communication, and that in particular the requirement that the heat exchangers be free from water was communicated using ambiguous wording, leading the project team to believe that simple draining of the heat exchangers would be adequate (draining was understood to allow for the possibility of some water retention). Following its investigation, the licensee has identified and committed to a number of actions relating to improving communications, including enhancements to staff training and briefing.
The conclusions of ONR's preliminary investigation concur with those of the licensee's investigation, and ONR is content with the licensee's response. ONR's investigation also concluded that changes already made to the licensee's arrangements (for reasons unrelated to this event) should serve to reduce further the likelihood of a recurrence.
With regard to the breach of the Carriage of Dangerous Good Regulations, ONR has applied its enforcement management model and has concluded that a verbal warning is appropriate.