A statement on incidents at nuclear installations in Great Britain and during the transport of radioactive material, which meet Ministerial Reporting Criteria (MRC), is provided to the Secretary of State for Business, Energy and Industrial Strategy and the Secretary of State for Scotland and Wales, and is published each quarter by the Office for Nuclear Regulation.
For the period, 01 January 2017 to 31 March 2017, there were two incidents which met the MRC.
Ministerial Reporting Criterion - Confirmed exposure to radiation of individuals which exceed or are expected to exceed, the dose limits specified in Schedule 4 to the Ionising radiation Regulations (IRRs) 1999.
The Magnox reprocessing plant takes Magnox-type fuels from a storage and preparation plant on another part of the Sellafield licensed site, and passes them through a series of chemical and mechanical processes, separating out the resulting material into a number of nuclear waste and product streams. As part of normal daily shift routines, a senior member of the plant staff takes samples to confirm that the plant’s processes are within expected parameters (for product quality, nuclear materials accountancy and safety purposes). Such sample taking is a routine daily activity.
On 8 January 2017 the individual person who undertook one of these samples, upon leaving and using the radiation monitors, found themselves to be contaminated. The licensee’s initial response was in accordance with its formal arrangements, and the contamination was removed using standard procedures, namely a series of local chemical washes, swabbing and monitoring of the area. No other means of removal was required on this occasion.
The licensee has completed an internal investigation into the event, and has put additional control measures in place to minimise the probability of re-occurrence, including a pre-job brief and separate observation and supervision of the sampling task by a second operator. The licensee has confirmed that the dose estimate exceeded the Ionising Radiation Regulations 1999 annual limit of 500 mSv for an external skin exposure.
ONR commenced a formal investigation into this event. Preliminary enquiries within that investigation established that the breaches were not as serious as first envisaged, and that no additional learning would be achieved by the completion of that investigation. Therefore, the formal investigation was ceased in accordance with ONR processes.
Ministerial Reporting Criterion - Confirmed exposure to radiation of individuals which exceed or are expected to exceed, the dose limits specified in Schedule 4 to the Ionising Radiation Regulations (IRRs) 1999)
Routine glovebox work on Finishing Line 6 (FL6) was taking place to empty the Rotary Vacuum Filter (RVF) glovebox sump in response to a level alarm. The operator’s first action used the normal plant methods; no equipment is removed from the sump to do this. As the alarm persisted, the operator proceeded to remove and clean the probe, a task the operator has performed before. When the probe was replaced, a cable became entangled, which prevented the probe assembly (a bracket) seating correctly. When removing this cable the operator felt a sharp pain in his left hand and immediately called Health Physics. It transpired he had received a wound with the potential for an internal radiation exposure.
No additional protection was being worn as this particular task had been assessed by Sellafield Ltd (SL) as not requiring additional protection (i.e. cut resistant gloves, as the probe should not have had any sharp edges). The individual was de-contaminated and has been given the appropriate support and aftercare. The plant was made safe and procedures amended to prevent re-occurrence of a similar nature.
This incident was followed up promptly by an ONR inspector, who was satisfied that the actions taken by Sellafield Ltd had been adequate.
An immediate Management Investigation (MI) was convened by Sellafield Ltd and they advised that the individual may have received 1 to 3 times the annual whole body exposure limit set by the Ionising Radiation Regulations 1999. Subsequently the individual provided additional biological samples which confirmed that the IRR99 limit had been exceeded.
ONR has taken the decision to undertake a formal investigation and this is currently ongoing.
INES Level 2 - "Incident" - denotes more serious degradations of the safety systems or with some, though not severe, consequences for people or the environment.