Collection

Sellafield Ltd incident reports and notices

Sellafield Ltd is committed to keeping the public informed about operations on the Sellafield site.

Below you will find details of operational issues and events.

Sellafield Ltd incident report – silo liquid imbalance – 12 November 2019

Routine liquor level monitoring on the Sellafield site has indicated there has been a recent leak from the Magnox Swarf Storage Silo, a legacy storage facility which is a priority for decommissioning.

In the 1970s there was a confirmed leak at the same plant and recent data suggests that this has reoccurred. This was always a known risk that we have prepared for. The regulators have been notified.

The building is partly sited underground, the area of the leak is also below ground and therefore there is no health risk to the workforce.

Movement of radioactive material through the ground takes many years and there is also no health risk to the local community.

At Sellafield, we have a well-developed programme to monitor the underground environment. There has been no change to conditions presently detected as a result of this leak. A well-established management plan is being followed to continue to monitor the current situation.

Contamination created as a result of the leak will be dealt with in line with the current ground remediation plan for the area surrounding the Magnox Swarf Storage Silo, once it is fully decommissioned.

The vital mission of removing waste from the Magnox Swarf Storage Silo remains the key hazard and risk reduction priority and this is scheduled to start in 2020. This event underlines how important the job is to get the waste out and to decommission the building.

Sellafield Ltd rated this event as an INES (International Nuclear and Radiological Event Scale) Level 2 (significant contamination within the facility into an area not expected by design). This has now been confirmed by the United Kingdom INES National Officer. There is no health risk to the workforce or the community as a result of any leak.

Sellafield Ltd incident report – sump tank levels – 19 October 2019

Sellafield Ltd has detected that the liquid levels in a concrete sump tank in the legacy ponds area of the Sellafield site have recently fallen.

The loss in levels was recorded following recent maintenance work on the tank.

An engineering team are assessing the tank and investigating the root cause of the liquid reduction.

As a precaution we have increased the local monitoring and detection systems around the tank.

There is no risk to the general public or the workforce. The relevant regulators have been notified.

Sellafield Ltd rated this event as an INES (International Nuclear and Radiological Event Scale) Level 1 (minor problems with safety components with significant defence in depth remaining). This has now been confirmed by the United Kingdom INES National Officer. There is no health risk to the workforce or the community as a result of this leak.

Sellafield Ltd incident report - failure of cooling water supply - 10 October 2019

A temporary failure occurred with one of the Sellafield site’s cooling towers that supplies cooling to the Thorp reprocessing plant.

A sluice gate in the cooling tower had been closed in preparation for a cell to be drained and isolated to then allow routine cleaning work to be carried out.

The cell was configured and drained in accordance with site instructions, however one of the sluice gates to the cell wasn’t fully sealed and continued to drain through a basin, resulting in the supply to Thorp cooling towers being stopped.

An alternative supply of cooling water was used before the Thorp cooling water system returned to normal. There were no other safety or environmental consequence as a result of this event,

The Environment Agency was notified and ongoing investigations are taking place.

Sellafield Ltd incident report - misconsignment of samples - 10 October 2019

During the successful demolition of the First Generation Reprocessing Plant Stack, some samples were taken of its concrete support. These samples were sent to a laboratory for analysis using standard techniques in the civil engineering industry.

This analysis helped to inform the demolition process for the chimney and to better understand the long-term performance of concrete of this age.

These were sent from the Sellafield site in error, using our arrangements for materials that are not subject to radiological classification.

We have conducted extensive research and analysis, which confirms that these posed no radiological risk to the public, the workforce or the environment.

Following the discovery, as an immediate step, Sellafield Ltd issued a communication to its workforce involved in releasing materials from site to reinforce procedures and expectations and placed a temporary embargo on this.

The company informed its relevant partner agencies and regulators of this incident, and is investigating the circumstances that led to this occurrence to ensure any lessons are learned.

Sellafield Ltd incident report - operations outside scope – 2 October 2019

A safety case produced for the continued safe storage of nuclear material in a storage facility on site was implemented outside Sellafield Ltd arrangements.

The chosen method of implementation was through a safety summary document in order to close the existing gap in safety case scope in a timely manner.

While undertaking an engineering inspection of the area to inform the development of the safety case in readiness for the next phase of operations relating to the material, the workforce were unaware of certain restrictions imposed and carried out an action – the removal of a dummy shield plug – that was outside of the scope of the safety case.

There was no safety consequence as a result of this action. Following the subsequent investigation this event was reclassified as an INES level 1 (anomaly) – shortfalls in the implementation of safety case changes and repetition of similar shortfalls relating to safety case compliance and oversight.

Sellafield Ltd incident report - sampling measurements exceeded – 1 October 2019

During routine sampling of a Thorp cooling tower on the Sellafield site, measurements of suspended particles were higher than expected.

Re-analysis and investigation confirmed a minor threshold exceedance due to ongoing operations at the time.

There were no radiological consequences and no harm to the workforce or the public as a result of this event.

Sellafield Ltd incident report - sewage treatment overflow – 26 September 2019

Daily suspended particle results in the water discharged from the Sewage Treatment Works were elevated on three occasions during August and September 2019.

During a routine plant check in November one of the settlement tanks was found to be discharging with water and particles that had been partially treated.

The levels have now returned to normal. These are known issues that are being dealt with through an improvement programme. The Environmental Agency has been informed.

There has been no measurable environmental impact as a result of these discharges.

Sellafield Ltd incident report - building evacuation at Sellafield – 4 September 2019

Monitoring equipment in a maintenance facility at Sellafield registered elevated levels of in-air activity.

As a precaution, and in-line with well-rehearsed procedures, personnel were evacuated from the building.

Operations in the facility were paused while analysis was carried out to ascertain the root cause.

Following analysis, 2 localised areas with increased levels of surface contamination were found within controlled areas. These were subsequently decontaminated to permitted levels.

During the event, slightly elevated stack discharge levels were detected, before the building ventilation was stopped. These were well below numerical permit levels.

There was no risk to site personnel or members of the public. A management investigation is underway to understand root and contributory causes.

Sellafield Ltd incident report - personnel contamination event – 1 August 2019

A person was treated for contamination to the hand after removing a weed from a duct adjacent to a walkway within a radiation controlled area on the Sellafield site.

A skin dose assessment confirmed that no significant radiation dose was received by the individual.

The surface around the location has been confirmed to be clean at natural background levels.

Sellafield Ltd incident report - demonstration of functional performance of packages - INES 1 - 9 July 2019

Following a review of the welding specifications used to seal the outer layer of a number of multi-layered cans storing special nuclear material, we identified a potential uncertainty regarding their integrity in a loss of cooling fault scenario.

As a result we have reviewed our procedures and introduced enhanced arrangements to both respond to this and for completion of the remaining package production programme.

The sealed cans are stored in a building which is automated and not normally accessed by workers. The cans and the store have numerous monitoring devices and controls to prevent any radiological consequence from the store in the unlikely event of a can weld failure.

In addition, a programme of work has been agreed with ONR, and is due to complete in 2019.

There are no safety consequences as a result of this issue. The issue carries an International Nuclear Event Scale 1 rating.

Sellafield Ltd incident report - discharge pipeline damage - 26 July 2019

A team leader at Sellafield Ltd discovered a leak from a short section of a lagoon discharge pipeline which runs under a concrete plinth.

The discharge pipeline is used to carry low level liquid effluent such as cooling water and rain water to the sea.

A team, with support from the site emergency services, generated a temporary diversion from the damaged section of pipe as an immediate response to the event and then put in place a temporary repair of the damaged pipe in order to return to normal operations. A more robust temporary pipe was then put in place to enable the final replacement to be procured and implemented.

Sellafield Ltd carried out an investigation and findings found that the pipeline had prematurely failed due to internal and external corrosion.

Reassurance monitoring found no contamination to the ground beneath the discharge line.

Sellafield Ltd incident report – flask non compliance – 7 May 2019

An empty transport flask, that was returning to Dounreay site in Scotland from Sellafield, was found to contain a small amount of metallic debris.

The flask is specifically designed to safely transport spent fuel and therefore there was no risk to the environment or the public from this transport.

We are investigating the cause of this misconsignment.

The relevant regulators have been informed.

Sellafield Ltd incident report – nitrogen oxides release – 19 February 2019

A Sellafield Ltd employee’s nitrogen oxides (NOx) monitor went into alarm in the Thermal Denitration plant as a result of a small NOx release from an ‘off gas line’ flange external to the building.

There has recently been maintenance work carried out during an outage in the plant, and there was no evidence to indicate that the flange that was found to be leaking had been reviewed during the outage.

The plant had operated on a number of occasions without any NOx being detected.

Operators are trained on the hazards of NOx and required actions if a leak is detected. Following the alarm the operator in the plant left the area and reported the issue to the operations team.

There was no safety or environmental consequence as a result of this condition.

Sellafield incident report – Container lid not welded correctly – 7 February 2019

During the process of cleaning an active waste container with water in the Waste Vitrification Plant (WVP), it was discovered that the container lid had not been welded as required.

Immediate actions following initial investigation findings included assessment of any potential consequences within WVP and downstream facilities, while operations were temporarily suspended.

A management investigation was also undertaken focusing on the robustness, usability and adherence of relevant procedures, training and supervision.

Relevant key learning will be applied to the rest of the Sellafield site.

There were no radiological consequences and no harm to the workforce or the public as a result of this event.

Sellafield incident report - Domestic water leak – 5 February 2019

The main domestic water supply pipe on site was found to be leaking.

Repairs have been carried out to the pipe and the leak has stopped.

Prior to the repair, silt fencing was installed to mitigate any silt run off. There was no sediment release observed.

The Environment Agency has been informed.

There were no safety implications and minimal environmental impact.

Sellafield incident report - Transport misconsignment – 18 January 2019

A spent fuel transport flask, which was consigned as empty and returned to Dounreay site in Scotland from Sellafield following the discharge of its contents at Sellafield, was found to contain a small amount of metallic debris.

The flask is specifically designed to safely transport spent fuel and therefore there was no risk to the environment or the public from this transport.

We are investigating the cause of this misconsignment. The relevant regulators have been informed.

Sellafield incident report – Nitric acid spillage – 18 January 2019

In January 2019 some nitric acid was found to be leaking from instrument pipework into a purposely designed bund on the Sellafield site.

The facility housing the bund (secondary containment) was evacuated while the Sellafield Fire and Rescue team isolated and contained the leak.

As a precautionary measure three people who were in the vicinity were taken to the site medical centre for reassurance checks but were later discharged and returned to work.

There were no injuries to personnel and no environmental consequences.

Sellafield incident report - Mixed metal consignment – 14 January 2019

A contractor that provides a metal recycling service for low level radioactive metals from the Sellafield site, received a mixed metal waste consignment from the site.

The metals waste contained rain water which was not disclosed to the waste recycling contractor and did not fall within its normal operating parameters.

There were no safety or environmental consequences.

Sellafield incident report – Asbestos discovery - 10 January 2019

During the breaking up of a concrete floor at our Lillyhall stores a contractor uncovered chrysotile asbestos (white asbestos) during the work activities.

The worker immediately withdrew from the area and a specialist contractor was called in to safely remove and dispose of the material.

A thorough investigation into the matter is underway.

Sellafield incident report - Discharge permit issue – 31 December 2018

Sellafield Ltd informed the Environment Agency after permitted discharge levels were exceeded at one of our plants.

Analysis of cumulative discharges at the Enhanced Actinide Removal Plant confirmed discharges of nickel during December 2018 had exceeded permitted levels.

Nickel is used as an additive to assist processing in the plant.

Sellafield Ltd has carried out a management investigation and will take action to address the findings. There were no safety implications and minimal environmental impact.

Sellafield incident report - Loss of cooling water/discharge to factor sewer - 13 November 2018

A loss of cooling water in the Thorp plant resulted in damage to a heat exchanger and a discharge into a sump.

Some of the cooling water was discharged via the factory sewer following an environmental assessment and a Discharge Approval. During this discharge, it was recognised that the environmental assessment and Discharge Approval did not include all dosing chemicals in the liquor, and the discharge was ceased. Another environmental assessment and Discharge Approval were produced before discharge of the remaining liquor.

The decision was taken to discharge the initial liquor owing to concerns about the sump level rising over electrical items.

There were no radiological or personal safety consequences.

Sellafield Incident report - Pressure washer leak – 23 October 2018

During an assessment of a controlled area within the Sellafield site, we identified a slow leak from an industrial pressure washer, resulting in contamination both within and outside the bund underneath the pressure washer. As a result, a small quantity of material entered the controlled area surface water drainage system. The quantity lost is not environmentally significant.

The surface water drains feed into a lagoon, and we have detected no increase in activity discharged from the lagoon.

We have carried out a detailed spillage assessment and concluded that there were no safety consequences, and the radiological release was well within regulatory limits.

We treat any unexpected discharge very seriously and we are investigating how this event occurred.

Sellafield Incident report – Ductwork defect – 12 October 2018 - updated May 2019

Sellafield Ltd has been carrying out improvement work on the ventilation systems associated with 2 ageing facilities on the Sellafield site.

As part of the improvement work, defects were discovered in locations relating to the ventilation ductwork outside the buildings in October 2018.

The first defect was discovered during a standard safety assessment of a steel ventilation duct wall connected to a material handling facility at Sellafield. Also, during maintenance work on a duct running from on-site laboratories, further defects were discovered.

The ducts provide extract ventilation from the buildings, and there was no measured loss of activity from the defects. The potential radiological impact on members of the public and the environment has been assessed as very low.

The Environment Agency served an enforcement notice which required Sellafield Ltd to repair the defects and improve maintenance.

In addition, Sellafield Ltd agreed with the Environment Agency that a wider inspection and repair programme for ventilation systems in other areas across the site and an independent review of Sellafield Ltd’s ventilation asset management arrangements would be undertaken. This wider programme will take around 2 years to complete.

As part of an extensive condition review across the site, minor defects have been discovered during the inspection of the external ventilation ductwork in 2 of the site’s decontamination facilities (February 2019) and the Active Handling Facility (April 2019).

The former ductwork carried the extract from the decontamination tanks, which have not been used for routine operations for over 2 years.

The initial event that prompted a wider review of the site’s ventilation systems carries an International Nuclear Event Scale Level 1 rating (an anomaly).

Sellafield Incident report – Power loss resulting from cable strike – 7 September 2018

During construction works for a new steam generation plant at the Sellafield site, an underground electricity cable was struck, leading to a temporary dip in power to parts of the site.

Those plants impacted by the dip applied their loss of power procedures to maintain the safety and security of the site.

No one was injured as a result of the cable strike and there were no environmental consequences.

Sellafield Ltd has carried out a thorough investigation, has been liaising with the Office for Nuclear Regulation, and is in the process of implementing the findings.

Sellafield incident report - Breach of written management system – 6 September 2018

During cleaning operations of the Sellafield Ion Exchange Effluent Plant (SIXEP) cooling tower system, the dilute cleaning chemicals are held in the cooling tower basin until they are suitable to be released to the environment.

This position is maintained by closing a valve which isolates the basin from the drain line and prevents inadvertent release of the basin contents. On a recent occasion, the required valve configuration - while following a quality plan - was not applied.

There was potential, under this configuration, for water from the basin containing the diluted cleaning chemicals to be discharged to the Calder Interceptor Sewer.

The Environment Agency has been made aware of this event and will be considering whether there is any non compliance with the Environmental Permit for the site.

Sellafield Ltd is carrying out an investigation and will take action to address the findings. There were no safety consequences.

Sellafield incident report - Misrouting of waste metal – 9 July 2018

We closely monitor and audit activities on the Sellafield site.

It was identified due to the diligence of this auditing process that some metallic waste which potentially contained asbestos had been sent to a facility not permitted to handle asbestos.

All of the waste concerned has undergone thorough radiological checks and does not contain any nuclear material.

We are working with the operator of this facility to understand what, if any, consequences arose as a result of the handling of this waste.

This investigation is ongoing and all of the relevant regulatory authorities have been informed.

Sellafield incident report - Cement grout washings overflow – 26 June 2018

While transferring cement grout washing liquid to a settling tank on the Sellafield site, a small amount of liquid was leaking out of the drainage area and into the exterior surface water drain.

The drain discharges to the River Calder, via a storm water outfall. The effluent that entered the drain was not radioactive.

Sellafield Ltd is carrying out an investigation and will take action to address the findings.

There were no safety or environmental consequences.

Sellafield incident report - Undisclosed items in mixed metal consignment – 22 June 2018

A contractor that provides a metal recycling service for low level radioactive metals from the Sellafield site, received a mixed metal waste consignment from the site that included a number of used, crushed metal containers that included residues.

The metals waste containing residues were not disclosed to the waste recycling contractor and did not meet its Waste Acceptance Criteria.

Sellafield Ltd has carried out an investigation resulting in actions to address the findings.

There were no safety or environmental consequences.

Sellafield incident report - Monitoring samples – 29 May 2018

Sellafield Ltd takes environmental monitoring samples from the Separation Area Ventilation stack sampler at Sellafield on a quarterly basis for analysis.

One sample is sent to Sellafield Ltd’s laboratories for analysis, while the other is sent to the Environment Agency.

The samples were taken but not issued to the regulator within the required timescales.

This is a breach of the regulator’s permit requirements. Sellafield Ltd is carrying out an investigation and will take action to address the findings.

There were no safety or environmental consequences as a result of this breach.

Sellafield incident report - Soil sampling process – 4 May 2018

During routine sampling and testing of small amounts of soil on the Sellafield site to ensure its suitability for reuse, the relevant project backfilled the excavated area prior to receiving confirmation that it was suitable for backfill.

The soil in the area where the sampling took place is considered low risk and there are no safety or environmental consequences.

An investigation has been carried out, and we are considering any actions required to address the findings.

Sellafield incident report – Ventilation system maintenance anomaly – 11 April 18

During routine maintenance work on the ventilation system of one of Sellafield Ltd’s intermediate level waste stores, an extract damper (valve) was left open resulting in air from the store bypassing the High Efficiency Particulate Air filters.

Once it was identified, the damper was returned to its correct position. The air leaving the store is continuously monitored and there were no safety impactions during that time.

Sellafield Ltd is carrying out an investigation, and will take action to address the findings.

Sellafield incident report – Water leak – 1 March 2018

Due to freezing temperatures at the beginning of March, there was a water leak from a water pipe on an elevated pipebridge on the Sellafield site.

As a result, water ran into nearby pipe trenches below ground level.

The volume of water resulted in a discharge through a number of non-routine routes, including a leakage to ground. The water carried very low concentrations of radioactive contamination.

The water was removed and safely disposed of via our robust processes. A management investigation has been carried out to understand the root cause and identify learning from the event.

There were no safety implications for the workforce or the general public.

The event carries a Nuclear International Event Scale Level 1 rating (an anomaly) based on ‘minor problems with safety components with significant defence in depth remaining.’

Sellafield incident report - Waste spillage – 6 February 2018

During routine sampling work in a product finishing line facility at Sellafield, a small number of contaminated waste items fell through the end of an unsealed bag causing the waste to fall to the floor.

The operator handling the samples was wearing the correct personal protective equipment, and the individual suffered no ill effects. Also, the contamination was contained within the immediate work area.

The material was immediately made safe and the area subsequently cleared of any contamination.

An investigation has been carried out, and we are considering any actions required to address the findings.

The event carries an International Nuclear Event Scale Level 1 rating (an anomaly) based on ‘minor problems with safety components with significant defence in depth remaining.’

Sellafield incident report - Powder spillage - 15 January 2018

During routine sampling work in a Sellafield drum filling area, a bottle containing uranium trioxide powder accidentally fell to the floor causing approximately 100-150g to spill out.

The operator handling the samples was wearing the correct personal protective equipment and the correct safety procedures were followed.

There was no personal contamination or ingestion by the operator and the contamination was contained in the immediate work area. An investigation has been carried out, and we are now considering the actions required to address the findings.

The event has been rated 0 (anomaly) on the International Nuclear Events Scale.

Level 1 represents the lowest severity, known as ‘anomaly’, rising to Level 7: ‘major incident’.

Sellafield incident report - Personnel contamination event - 28 November 2017

An employee was contaminated during operations in one of our analytical laboratories at Sellafield.

This was identified following routine internal dosimetry monitoring tests which are carried out on our nuclear workers.

An assessment confirmed that the radiation dose received was significantly less than the annual limit allowed for an individual.

The employee suffered no ill effects and did not require any time off work.

Sellafield incident report - Chemical event - 20 October 2017

A chemicals inventory check in our Analytical Services building identified potentially hazardous chemicals requiring safe disposal.

In line with industry best practice, we requested the assistance of the Army’s Explosive Ordnance Disposal (EOD) team to assist with these disposals. The appropriate disposal methodology was controlled detonation by the army’s Explosives Ordnance Disposal team (EOD).

Following the safe disposal of hazardous chemicals, Sellafield Ltd established an investigation to understand the causes and gain learning from the event.

The findings from this investigation can be viewed here: Chemicals Disposal Investigation Report

The safe, secure stewardship of the Sellafield site is our overriding priority and underpins every decision we make, from clean-up and waste management operations to the safety of our people, care for our environment and the security of nuclear materials.

The event carries an International Nuclear Event Scale Level 1 rating (an anomaly).

Sellafield incident report - Powder spillage - 14 June 2017

While carrying out analysis work in a Sellafield site laboratory, a worker spilled approximately 1kg of depleted uranium trioxide powder while moving a container.

The material is not harmful unless ingested or inhaled.

The correct safety procedures were followed and the immediate area was evacuated before returning to normal service on the same day.

Health checks confirmed the worker suffered no ill effects.

An internal investigation is being carried out.

The event carries an International Nuclear Event Scale Level 1 rating (an anomaly).

Sellafield is regulated by the Office for Nuclear Regulation and the Environment Agency.

Some of these reports are graded using the International Nuclear and Radiological Event Scale (INES).

See details of incidents at Sellafield before 1 August 2017

Published 10 June 2017
Last updated 10 December 2019 + show all updates
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  15. Updated 21 June 2018

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