Two Sellafield workers have been officially cautioned by the Office for Nuclear Regulation (ONR) for carrying out unauthorised work in the highly sensitive facility that contains the site’s High Level Waste Storage Tanks (HASTS). The cautioning of individuals by the ONR is unprecedented, with regulatory action historically taken against the company (Sellafield Ltd) itself rather than individual workers.
Reported on its website on 1st May 2014, ONR’s investigation found that, in attempting to remedy a fault on one of the suite of highly radioactive HASTS, two workers had removed a contaminated and malfunctioning resistance thermometer from a pocket on one of the HASTS in December last year. The incident, contrary to the Health & Safety at Work Act 1974, was caused ‘solely by the acts and omissions of the individuals, in full knowledge of what was required by the company to safely control and carry out the work. This was a direct violation of established, well-known and obvious risk control measures and arrangements for working with ionising radiation implemented by the employer’.
This unauthorised action by the workers had not only exposed them the elevated levels of radiation – though within proscribed dose limits – but had also resulted in the spread of radioactive contamination into another area of the HAST complex which was ‘not specifically designed, maintained or used to prevent the spread of contamination’ and had therefore posed a serious health risk to the two individuals and to other workers.
The formal caution is used by ONR as an administrative tool where a criminal prosecution could have been brought but where specific circumstances weigh against it. In signing the formal caution, the two workers accept that if they are found guilty of any other health and safety related offence over the next five years, this caution may be referred to in any subsequent legal proceedings.
In its previous life as the Nuclear Installations Inspectorate (NII), the ONR has routinely raised concerns about the robustness of the steel tanks that hold the highly radioactive and thermally hot liquid wastes produced by Sellafield’s reprocessing operations. The tanks, which have suffered a number of ‘loss of coolant’ events over the years, require round the clock cooling through a system of internal cooling coils and external cooling jackets – a system that has suffered corrosion problems and degraded over the years. Should reprocessing operations have to continue beyond the currently scheduled closure dates for the THORP and Magnox reprocessing plant (2018 and ~2020 respectively) ONR would require new HASTS to be fitted in Sellafield’s Highly Active Liquor Evaporation and Storage (HALES) facility at an estimated cost of £500M.