Sellafield Ltd incident reports and notices
Source: gov.uk (2025-12-10)

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 – Crane collision – 18 June 2025

While undertaking a statutory inspection of the 15-tonne crane in the Fuel Handling Plant on the Sellafield site, scaffold erected on the crane for the purpose of the inspection collided with a ventilation duct.

The maintainers driving the crane immediately halted operations. The crane was then electrically isolated. Lifting operations were suspended and a group was set up to manage its recovery.

Upon inspection, it was found that damage to the ventilation duct was minimal. However, the collision resulted in a lightweight retractable walkway (part of the crane) moving slightly from its 2 runners.

There was no potential for injury to personnel and no potential for radiological or environmental consequences as a result of this event. Crane activities have now resumed.

Sellafield Ltd rated the event as an INES (International Nuclear and Radiological Event Scale) Level 1 – Anomaly, due to the procedural inadequacies with significant defence in depth remaining.

Sellafield Ltd incident report – Dislodged can – 28 May 2025

During routine swabbing operations in one of the Special Nuclear Materials facilities on the Sellafield site, a can weighing 5.5kg was knocked from its position on the can channel access platform to the floor, a drop of 700mm. The dislodged can was recovered from the floor without any radiological consequences.

A Management Investigation (MI) was established, and the regulator informed.

There have been no nuclear, radiological, safeguards, environment or security consequences as a result of this event.

Sellafield Ltd rated the event as an INES (International Nuclear and Radiological Event Scale) Level 1 – Anomaly, minor problems with safety components with significant defence in depth remaining.

Sellafield Ltd incident report - Crane re-roping - 17 April 2025

During maintenance by a specialist crane contractor to replace the crane steel wire ropes on the 80 tonne crane used to move intermediate level waste flasks in the Encapsulated Product Store 1, the crane rope lowered off the crane in an uncontrolled manner on to the scaffold platform approximately 18 metres below.

Removal of the rope was an essential preparatory step to enable access to and replacement of the crane’s brake system.

The uncontrolled lowering of the crane rope did not cause physical injury to those workers involved in its removal.

Following the incident, a safety stand down and site wide briefings took place, and a revised method was used to maintain the crane. An internal investigation was carried out to understand the root cause and contributory causes. The regulator has been informed.

Sellafield Ltd incident report – Lead flooring sheet – 8 April 2025

During operation of the Skip Handler Machine in the First Generation Magnox Storage Pond (FGMSP), it was observed that the flexible lead sheets used for radiological shielding were in a degraded condition resulting in a visible covering of lead oxide.

The Skip Handling Machine is used to recover the waste skips from the pond.

The area where the lead sheeting was discovered has a low footfall, is in a controlled radiological area and there are additional controls in place to prevent individuals coming into contact with the lead sheets.

Following the discovery, access to the Skip Handling Machine was prevented, an investigation was initiated and the regulator informed. There were no safety, personnel or environmental consequences.

Sellafield Ltd is working with its regulator to review its arrangements with respect to the Control of Lead at Work Regulations, including routine visual inspections, to ensure statutory compliance is achieved across the site.

Sellafield Ltd incident report - Loss of power – 25 January 2025

The Sellafield site lost power to a section of the site as a result of Storm Eowyn.

Several building emergencies were declared resulting in multiple facilities enacting their standard evacuation protocols.

The power outage also affected several IT and communications systems.

Power was reinstated and all faults were restored.

We are currently in the process of conducting a review of our electrical resilience and have identified a number of actions and prioritised improvements.

There have been no safety or environmental consequences and the regulator has been informed.

Sellafield Ltd rated the event as an INES (International Nuclear and Radiological Event Scale) Level 1 – Anomaly, minor problems with safety components with significant defence in depth remaining.

Sellafield Incident Report – Drain valve alignment – 13 January 2025

During routine housekeeping checks in a waste storage facility on the Sellafield site, an operator witnessed a drain valve that was open when it should have been closed. Closer inspection revealed that although the padlock on the valve was still in the locked position, the padlock was damaged and the valve was able to move freely.

This prompted a further inspection in the area which identified other drain valves that were able to be opened or closed, even when padlocked, due to the screws attached to the drain valve working themselves loose over time.

In response to this event, all operations teams were briefed on the importance of the correct procedures being used for plant configuration, and a management investigation undertaken to understand the root cause and any contributory causes.

These causes are being addressed and include engineered modifications to prevent future occurrences.

There were no radiological or environmental consequences as a result of this event.

Sellafield Ltd rated the event as an INES (International Nuclear and Radiological Event Scale) Level 1 – Anomaly, minor problems with safety components with significant defence in depth remaining.

Sellafield Ltd incident report - Flask events – 20 November/12 December 2024

Over the course of a month there have been 2 separate and isolated incidents involving contaminated flasks.

On both occasions flasks of medium active waste were being exported via the site road network from the High Level Waste Plant (HLWP) to the Miscellaneous Beta Gamma Waste Store (MBGWS). The flask radiological surveys carried out in HLWP prior to dispatch recorded readings below action levels.

When health physics monitors carried out the initial incoming radiological survey of the flasks at the MBGWS, the instrument readings showed some contamination on the base of the flasks and their transport trollies.

There have been no safety, personnel, or environmental consequences.

An investigation is underway, and the regulator (ONR) has been informed.

Sellafield Ltd incident report - Flatrol collision – 02 November 2024

As part of routine operations on the Sellafield site, flatrol railway wagons carrying flasks of spent nuclear fuel are transported via the Sellafield site railway system into the Fuel Handling Plant.

During a shunting operation to move a flask into the Fuel Handling Plant, there was a collision between two flatrols.

Both flatrols sustained minor damage, neither flatrol was de-railed, no one was injured and there were no radiological or environmental impacts as a result of this incident.

We take all site incidents seriously. An internal investigation was carried out, alongside working with our regulator, to review our planning, control and monitoring of all our rail activities to ensure preventative and protective health and safety measures were in place. This resulted in a review and update of relevant policies and procedures to prevent this from happening again in future.

Sellafield Ltd Incident Report – Holes in ductwork – 18 July 2024

As part of an inspection of external ventilation ductwork in Analytical Services on the Sellafield site, areas of delamination and a small hole were identified.

The area was subsequently surveyed and it was confirmed that there were no radiological consequences.

A repair was then carried out, additional defence measures put in place including enhanced monitoring systems in the area, and an improvement schedule produced that included further repairs.

There has been no harm to individuals and plant operations were unaffected.

We are working with the Environment Agency regarding on-going improvements.

Sellafield Ltd incident report - Failure to follow procedures – 12 June 2024

Sellafield Ltd has a facility that transfers waste product from a treatment plant into a drum for onward encapsulation and storage.

During a reverse pumping activity, it was identified that work was carried out in a way that did not meet the required standards set, within the existing risk assessment protocols.

This failure to correctly follow existing controls identified through assessment of risk could potentially have resulted in a spread of contamination to the individuals involved and the work area.

There was no harm to individuals and plant operations were unaffected. The regulator has been informed.

Sellafield Ltd rated the event as an INES (International Nuclear and Radiological Event Scale) Level 1 – Anomaly, safety layers and barrier depth to consequence identified.

Sellafield Ltd incident report - Nickel discharges – 16 May 2024

The Enhanced Actinide Removal Plant (EARP) purpose is to remove activity from medium active and low active liquid waste streams across the Sellafield site prior to discharge to sea.

The permit limit for nickel discharges to sea from EARP is assessed monthly. Results for the sampling in March 2024 indicated that nickel concentration had exceeded the permit limit, and further analysis confirmed the results.

On discovery of the results, all further EARP discharges were put on hold and investigations initiated.

A non-radiological impact assessment was then undertaken that demonstrated the environmental impact of the nickel discharge was insignificant.

All operations have resumed, and the regulator informed.

Sellafield Ltd incident report - Nickel Nitrate containment – 15 April 2024

An inspection of a chemical preparation area in one of our effluent facilities on the Sellafield site found traces of nickel nitrate outside of its primary containment cabinet.

Nickel nitrate is a non radioactive compound used in a range of chemical processes including the treatment of effluents.

Following the inspection, enhanced monitoring and cleaning of the affected area was carried out.

As with all site incidents, we are taking this extremely seriously. A formal investigation was completed to understand the root cause and to prevent this from happening again in future.

We have worked closely with our regulator to bring about the required Control of Substances Hazardous to Health (COSHH) improvements to address two Improvement Notices, and in October 2024 we met the requirements of the first Improvement Notice by completing an assessment of the risks associated with the use of nickel nitrate.

The second Improvement Notice was closed out in September 2025 following work to implement suitable control measures to reduce the risks to workers from exposure to nickel nitrate.

Sellafield Ltd incident report - Building evacuation – 25 February 2024

A recent trip on a Sellafield substation resulted in a number of buildings within the Low Active Effluent Management Group (LAEMG) area losing power.

As a direct result of the trip, affected buildings in the area were subsequently shut down and building emergencies declared. A roll call took place across the affected building with all personnel accounted for.

After confirming the extent of the power loss, steps were then taken to monitor plants until the power was restored. Once power was restored, monitoring of the affected plants confirmed that there were no issues.

There was no risk to the public, workforce or the environment.

Sellafield Ltd incident report - Pipework inspection - 25 January 2024

During routine checks, pipework inspection was carried out by Sellafield Ltd personnel in a support plant room adjacent to a Qualifying Nuclear Material (QNM) store.

The Sellafield Ltd inspection took place with all relevant personnel present; however, no support plant room entry notifications were made to the International Atomic Energy Authority (IAEA) as per regulatory protocol.

As per agreed arrangements, an electronic seal on the QNM support plant room door was detached, and the door opened using a key controlled by the Shift Team Manager (STM).

On completion of the pipework inspection the plant room was exited, the door locked, the seal was reconnected, and the key returned to the STM. A record of the entry was made in the shift log.

Following an IAEA inspection, it was observed that the door was locked but the seal wasn’t reconnected correctly, resulting in the inspector reconnecting the seal.

IAEA has confirmed that no entry was made to the Qualifying Nuclear Material (QNM) store.

Sellafield Ltd subsequently carried out an investigation resulting in a number of outcomes including a review of operator instructions, updated briefings on entry arrangements and visual operator aids.

There were no safety consequences as a result of this event and the regulator has completed follow-up inquiries.

Sellafield Ltd incident report - Classified workers – 02 January 2024

A routine review of the workforce classified persons status was undertaken across the site, with the results identifying a number of employees that should be transferred from a monitored worker to a classified person status, as a result of their normal work activities.

Classified Person designation is used for employees who meet the requirements within the Ionising Radiations Regulations and carry out activities with defined levels of risk when working with Ionising Radiation.

A programme has been put in place to convert identified monitored workers into classified persons where required.

Meanwhile, a management investigation is in progress.

There are no impacts to the workforce, public, or the environment and the regulator has been informed.

Sellafield Ltd incident report - Contamination of classified area – 28 November 2023

During routine monitoring, low levels of radiological contamination was found on the shoes of 2 people working in a contamination controlled area of the Thermal Oxide Reprocessing Plant on the Sellafield site.

Additional reassurance monitoring by our health physics team identified further contamination in the surrounding controlled area.

Access to the area was restricted and immediately decontaminated. A management investigation is underway into the cause of the contamination.

Sellafield Ltd rated the event as an INES (International Nuclear and Radiological Event Scale) Level 1 – Anomaly. Shortfall in work practices including minor problems identified with safety components with significant defence in depth remaining.

There are no impacts to the public or the environment.

Sellafield Ltd incident report - Loss of Power - 22 October 2023

A recent failure of a power cable between 2 substations resulted in a site wide power dip.

Following the power dip and in line with company procedures, a number of facilities on the Sellafield site initiated building evacuations and emergency arrangements, to manage recovery from the power dip.

Following the restoration of power, we were able to return the lost substation back to normal operations.

This cable system is recognised as a degraded asset and as part of our site wide infrastructure resilience programme, is currently undergoing repair and upgrades.

There was no risk to the public, workforce or the environment and the regulator has been informed.

Sellafield Ltd incident report – Sewage Treatment Works suspended solids – 16 October 2023

Following routine effluent sampling, an elevated ‘suspended solids’ result has been measured in the Sellafield site, Sewage Treatment Plant.

The resulting measurement is above the permitted limit.

There had been no increasing trends from the plant or abnormalities leading up to the elevated result.

To facilitate further investigations and to understand the cause of the elevated levels, additional samples have been taken from the site outlet pipe and from within the Sewage Treatment Plant settlement tanks.

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

Sellafield Ltd incident report – Small fire – 05 October 2023

Whilst carrying out laser cutting size reduction operations within a Skip Size Reduction Facility on the Sellafield site, the team involved in remotely operating the laser observed a minor fire emanating from the laser cutter’s conveyor mechanism.

As a result, the building fire evacuation protocols were initiated and followed.

Sellafield Ltd Fire and Rescue attended the scene and extinguished the minor fire, and there was no significant damage to plant equipment.

The laser cutting process is remotely operated in a closed module and whilst in operation is observed continually via remote CCTV, ensuring no personnel are in the immediate area during cutting operations.

There were no nuclear or environmental safety consequence as a result of this incident. An investigation has been initiated and the regulators have been informed.

Sellafield Ltd incident report – Breach of operating rules – 29 September 2023

The Plutonium Fuels Storage Facility has a number of operating rules associated with the safe storage of Magnox Reprocessing product containers.

One of the rules state that within 2 months of a container being placed into a purpose built facility, 2 analytical sampling procedures are required.

In December 2022 Sellafield Analytical Services stated that they would not be able to support ongoing analytical procedures.

To remain compliant with the operating rule, the decision was made to switch to a different analysis provider.

However, in January 2023, the new provider identified an issue that prevented the transfer of samples to their facility for analysis.

This had the potential to impact the completion of the product container programme, therefore a decision was made to continue with container operations alongside a revised inspection regime.

The revised inspections of the cans resulted in no issues but did result in a breach of the original operating rule in relation to the specific inspection methodology.

There were no safety consequences as a result of the breach and the regulators have been informed.

Sellafield Ltd incident report - Routine Alarm Maintenance – 31 August 2023

Staff were preparing to carry out routine maintenance on a Criticality Incident Detection (CID) System power supply unit in a building within the Sellafield site’s chemical separation area.

The main safety function of the CID System is to warn individuals of the need to evacuate the area, in the quickest possible time, in order to mitigate any impacts on individuals.

Building occupants were informed via the facility’s tannoy system that the work was being carried out and that the background ‘clicks’ that provide reassurance and demonstrate that the system is working effectively, would be switched off. Occupants were also told not to respond in the event of the alarm sounding.

While the power supply was being worked on and the background ‘clicks’ were silent, the CID system alarm sounded unexpectedly.

All of the building occupants followed the correct procedures by not evacuating.

However, several people outside of the building who would not have been aware of the ‘do not respond’ instruction were observed to continue to approach the facility while the alarm was sounding and a small number within an adjoining facility did not follow the correct procedures and evacuate the area, in line with our emergency arrangements.

The alarm sounded for approximately 1 to 1.5 minutes before staff successfully resolved the cause of the unexpected alarm and reinstalled the CID alarm system.

Given the way in which some individuals responded, this has been classed as an inadequate response to an unexpected criticality alarm.

There was no risk to the public, workforce or the environment and the regulator has been informed.

Sellafield Ltd rated the event as an INES (International Nuclear and Radiological Event Scale) Level 1 – Anomaly. shortfalls in the Prompt Evacuation Zone arrangements and inadequate response to a criticality alarm following the maintenance activity.

Sellafield Ltd incident report – Oil fuel leak – 11 July 2023

During a routine inspection of the off-site Combined Heat and Power Plant boiler park, an operator noticed fuel oil seeping out from under the boiler park roller shutter door.

Upon further inspection it was found that the fuel oil was coming from a leaking vent port on a fuel oil system pressure safety valve. The normal function of the valve is to protect the fuel pumps from damage.

Engineers quickly stemmed the leak and confined the spill to the immediate area using spill kits.

It was estimated that the volume of fuel oil lost from the vent port was approximately 800 litres.

There were no safety consequences as a result of this incident and the regulators have been informed.

Sellafield Ltd incident report – Dropped load – 28 June 2023

Items of equipment used for remote maintenance activities are routinely transferred from buildings on the Sellafield site to specialist maintenance facilities using a purpose-built transport flask. The flask contains internal lifting equipment, including a grab that connects via a lifting pintle to the item of equipment being moved.

Under normal operations the flask is placed above the item requiring maintenance, the grab is lowered, connects with the pintle and lifts the item up into the flask. The flask is then closed and transferred to the maintenance facility.

Once inside the facility, the flask is placed on top of a shielded cave, opened and the item is lowered into the cave. When the item is ready to be moved to a separate maintenance cave within the building, the operation is reversed.

While attempting to lift a pump back into the flask, the grab within the flask and lifting pintle attached to the pump separated, causing the pump to drop back onto the cave floor. The pump weighed 1.4 tonne is 2 metres long and dropped a distance of around 8 meters.

Containment of the cave remained intact and radiological monitoring has confirmed no elevated contamination levels either outside the cave or through the cave ventilation extraction systems.

Initial assessments show that the cell posting gate and equipment frame experienced some damage.

There were no safety or environmental consequence as a result of this incident. A management investigation has been initiated and the regulators have been informed.

Sellafield Ltd incident report – Building Evacuation – 16 May 2023

Cumbria Fire and Rescue attended the Sellafield site in response to a suspected fire at the Site Ion Exchange Effluent Plant (SIXEP). The building was temporarily evacuated as a precaution.

Initial investigations suggest a plastic bucket began to smoulder after being placed in close proximity to a high-pressure steam valve.

No personnel were injured and there were no radiological consequences.

A full investigation into the cause is underway and the regulator has been informed.

Sellafield Ltd incident report – Spark inside junction box – 5 May 2023

While carrying out the removal of a broken part (a Microsen Unit) from a crane on the Sellafield site, there was a spark inside the junction box of the broken part due to an individual pulling on a cable.

It is reported that the cable at the time was understood to be dead. An initial investigation indicated that there may have been the presence of other electrical supplies in the vicinity.

There was no harm to the individual and an investigation is underway to understand the cause.

Sellafield Ltd incident report – Activity alarm sounded – 13 April 2023

Following the removal of a robotic arm from the pond area of the First Generation Magnox Storage Pond for maintenance, a health physics monitor and commissioning engineer performed non-contact dose readings of the surrounding area to gain an understanding of radiation levels.

Although not requested as part of the reading the workers also swabbed the robotic arm, resulting in disturbed particulate activity on the arm and causing a portable activity in air monitor to go into alarm.

The workers were wearing the prescribed personal protective equipment and respiratory protective equipment. For reassurance, additional dosimetry assessments have been undertaken.

There were no safety or environmental consequence as a result of this incident. A management investigation has been initiated and the regulators have been informed.

Sellafield Ltd incident report – Extract fan bellows failure – 30 March 2023

During routine operations exporting waste drums from a cell in the Sellafield site’s Waste Packaging and Export Plant, the cell extract fan failed.

The failure was picked up when instruments designed to monitor cell depression went into low alarm.

Upon investigation, it was discovered that the extract fan bellows had torn, resulting in the fan tripping.

The fan equipment is part of the cell ventilation system, and its main function is to minimise the spread of any airborne activity to operating areas within the building.

The cell ventilation system includes a set of primary and secondary high efficiency particulate air filters installed between the cell and the damaged extract fan bellows.

There are also installed activity monitors between the filters, and on the discharge stack, none of which detected migration of activity.

In order to safely manage the issue, and in line with our emergency arrangements, a building emergency was declared.

The fan was repaired and restarted within a few hours. There were no nuclear or environmental safety consequences and the regulators have been informed.

Sellafield Ltd incident report – Offsite disposal – 20 March 2023

Four redundant shielded windows from a nuclear building on the Sellafield site were sent to an offsite waste processing facility for disposal.

When the windows were unloaded they were monitored by the local health physics monitor as part of routine arrangements, and surface contamination was detected on the wooden trailer bed.

The contamination was greater than the permitted transport level.

Additional reassurance monitoring confirmed that there was no contamination externally to the vehicle, on the ground, or at any of the locations the windows had been stored.

There were no safety consequences as a result of this incident.

Sellafield Ltd incident report – Power dip – January 2023

On the 01 January a power loss was experienced on the Sellafield site due to a fault on an on-site grid transformer.

As the recovery from the loss was ongoing, an additional power dip was experienced as a transformer feeding one side of a substation tripped causing a loss of electrical supply to the east side of the Sellafield site and a power dip elsewhere.

Power was restored to most areas within 15 minutes. Normal power was restored to all areas within 2 hours.

A second power dip occurred on the 21 January where an on-site grid transformer went offline due to a failed cable sealing end. The transformer was isolated to make it safe.

The power dip led to a loss of power in several areas, which was quickly reinstated. There was some further work to reinstate heating and hot water.

A management and electrical technical investigation is being undertaken for both incidents, which are not related to each other.

There was no risk to the public, workforce or the environment from these incidents and our regulators are being kept fully informed.

Sellafield Ltd rated the power loss on 01 January as an INES (International Nuclear and Radiological Event Scale) level 1 anomaly (minor problems with safety components with significant defence in depth remaining).

Sellafield Ltd incident report – Leak of water – 18 January 2023

A water leak from the air handling unit was identified in Encapsulated Product Store 3 at the Sellafield site.

An inspection determined that the air handling unit cooling coil had frozen and split causing a leak. The air handling unit room flooded on the non-active side of the plant and spread to the active side.

A building emergency was briefly declared, and a recovery plan was put in place. The building remained operational due to the recovery efforts, with no damage to plant or equipment.

An investigation was initiated, and the regulator informed. There were no environmental or safety consequence as a result of the event.

Sellafield Ltd incident report - Chemical spill – 10 November 2022

A very low concentration caustic tank overflowed into a secondary containment bund at the effluent plant services building at Sellafield.

The plant provides chemicals to other plants in Low Active Effluent Management Group for routine operations.

As a precautionary measure part of the building was evacuated while Sellafield Fire and Rescue, with the support of Cumbria Fire and Rescue, responded to the incident.

The caustic was safely contained, retrieved and disposed of via the appropriate route.

No personnel were injured and there were no radiological consequences as a result of this incident.

The site continued to operate as normal.

Sellafield Ltd incident report - Water leak – 8 November 2022

A leak from a tower cooling water pipe caused a flood within a compressor room on the ground floor of the Thorp facility that raised a series of alarms.

On investigation, the leak was found in one of the process air compressors. The compressor was immediately switched off and cooling water isolated, stopping the leak. There was no loss of process air, with the standby compressor coming on-line.

Bunds were set up within the compressor room to contain the water that contains low levels of biocides used for legionella control.

An Incident Control Centre was set up and a building emergency declared. Sellafield Fire and Rescue was in attendance.

The water was recovered and collected into intermediate bulking containers just outside of the facility where it was held until the appropriate authorised discharge route was confirmed.

There was no nuclear safety, environmental, conventional, or radiological consequences, and operations continued as normal.

Sellafield Ltd incident report – inadequate fire detection system – 3 November 2022

Following an engineering review in early November 2022, the First Generation Magnox Storage Pond (FGMSP) fire detection system was deemed to be inadequate.

All operations were paused, all non-essential personnel were restricted from entering the facility and enhanced surveillance was carried out while maintenance and repair of the system took place.

Sellafield Ltd worked through a recovery plan, in consultation with the regulator, to bring the facility back into operation in a phased approach.

This work included fixing the current fire detection system faults, the subsequent installation of a wireless system while enhancing mitigation measures in the facility such as fire risk assessments and enhanced access controls.

An investigation to understand the root cause of the event is ongoing in collaboration with the NDA to identify local and wider learning regards fire protection.

Sellafield Ltd incident report – Building emergency – 18 October 2022

A building emergency was briefly declared in SEMAS (Salt Evaporation and Medium Active Storage) due to a temporary loss of ventilation in the separation area ventilation system during a fan changeover.

The alarm was sounded and building emergency declared. Ventilation was quickly restored, and there were no nuclear safety or radiological consequences.

Sellafield Ltd incident report – Flatrol contamination – 30 September 2022 and 5 October 2022

As part of normal site operations, transport flasks are routinely sent to EDF power stations around the UK.

A flask which was received at Heysham B power station was identified as having contamination on the flatrol used to transport the flask.

Subsequently a flask arriving at Hinkley Point B was also identified as having contamination on the transport flatrol. Elevated readings were also recorded on the base of one of the flask feet. No other areas of the flasks were found to be over the expected levels.

Sellafield Ltd initially paused the transport of flasks off site while detailed radiological surveys of the flask processing route at Sellafield Ltd were carried out.

An investigation has been completed, and we’ve introduced some updates to our arrangements including additional monitoring and rail transporter foot plate bags replaced on each journey.

There was no risk to the general public or the environment from these incidents and our regulators are being kept fully informed.

Sellafield Ltd incident report - Contamination of redundant flask lid – 22 July 2022

During reassurance monitoring of a redundant transport flask lid at an off-site metals recycling facility, 2 small areas of contamination were detected.

The flask lid has been returned to the Sellafield site and will be processed via the appropriate waste route.

Additional monitoring has taken place and an investigation is underway to determine the cause of the contamination.

There was no risk to the public, the workforce, or the environment.

The regulators have been informed.

Sellafield Ltd incident report – Contamination of redundant pipework – 23 June 2022

During a routine radiological survey of redundant pipework associated with the Product Finishing and Storage Plant at Sellafield, contamination was detected on a section of pipe and on the ground below.

The pipework is a historic condensate drain line that runs external to the building in a controlled section of the Sellafield site with low occupancy.

The pipework has been wrapped in a protective covering while we carry out an investigation into the cause of the contamination.

No personnel were harmed and there were no impacts on the operations of the Sellafield site.

The regulator has been informed.

Sellafield Ltd incident report – Reportable dose - 25 May 2022

A Sellafield Ltd employee has received a radiation dose which takes them above the annual whole body dose limit set for workers.

The intake was identified as part of our routine dose assessment programme.

Following an investigation and further dose assessments, we have rated this event as an INES (International Nuclear and Radiological Event Scale) Level 2 (Exposure of a worker in excess of the statutory annual dose limits.

We have continued to keep the individual and our regulators informed throughout our investigations.

Sellafield Ltd incident report – Core drilling incident – 19 March 2022

Specialist contractors were carrying out core drilling as part of an electrical distribution system upgrade project on the Sellafield site.

As they were carrying out the work and when the drill they were using was withdrawn from the work surface, a buried conduit with several copper cores was exposed.

The drilling machine was a class 1 portable device with inbuilt safety features that ensures all external metal parts are earthed through the supply cable. This would have directed any potential fault current straight to earth and away from the operator and ensured operation of the fuse protecting the circuit.

There was no harm to the contractor and plant operations were unaffected.

The regulator has been informed.

Sellafield Ltd incident report - Elevated reading on filter change - 02 December 2021

Sellafield Ltd encountered higher than normal levels of radiation during a routine change of the primary filters linked to the liquid effluent sea discharge system at Sellafield, suggesting solid particles were present.

There has been no activation of the installed radiation monitor on the discharge line downstream and the secondary filters have not been outside usual parameters.

Liquid effluents are treated and monitored through a range of facilities across the Sellafield site, and discharges to the environment are controlled in accordance with our environmental permits.

The route to sea discharge is via a break pressure tank. Flows are filtered through 2 filter units (primary and secondary) and radiation levels monitored as part of the discharge arrangements through the sea pipeline.

As a consequence of the elevated radiation readings, site discharges via this route were temporarily paused in December 2021 while the source of potential solid particles was investigated.

This investigation continues and samples of solid particles have been submitted for technical analysis.

Discharges have been resumed and in the interim we have introduced additional controls and monitoring enabling us to maintain nuclear safety and minimise the potential for any environmental impact.

A formal investigation has been convened and regulators and key stakeholders continue to be kept up to date with the progress of this work.

Sellafield Ltd incident report - Small fire in building – 22 October 2021

A small fire in a building associated with the Magnox Reprocessing Plant at Sellafield was quickly extinguished by the Sellafield Fire and Rescue Service.

The building occupants were alerted to the fire - which was associated with plastic scaffolding boards within the area - via the building fire alarm and they evacuated the facility in line with emergency instructions.

Once the fire was extinguished the fire crew confirmed that there was no further risk, and a facility team then carried out a controlled shutdown of equipment in the building.

The follow-up investigation identified a number of operational improvements. These have now been implemented and recovery work carried out including repairs to electrical cables.

There were no injuries and no nuclear, radiological or environmental safety issues. Sellafield Ltd have liaised with the Office for Nuclear Regulation regarding the event.

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)

Sellafield Ltd incident report - Individual fall – 12 October 2021

While carrying out repair work on an internal pipeline in the Magnox reprocessing facility at Sellafield, a site worker injured his back falling from a scaffolding ladder.

Two workers had successfully completed the repair work, with the first individual descending the ladder before the second person slipped during descent causing him to fall backwards and strike his back against a concrete pillar.

The injured person was assessed by occupational health on the Sellafield site and then transferred to the local hospital for further treatment.

The findings from our follow-up investigation include reviewing our relevant risk assessments and training pack.

Our regulator has been regularly updated about the incident.

Sellafield Ltd incident report - Telephone system impact – 21 September 2021

A new telephone system used at Sellafield experienced operating difficulties resulting in an intermittent impact to the system.

Impacts across the Sellafield site were not uniform, however the pager system and computer-based communications remained unaffected. In the Magnox Reprocessing Facility both the telephone system and analogue telephone land lines were lost, and precautionary measures were put in place.

An inquiry was carried out and the work to upgrade the telephone system has been completed.

There was no safety consequence and no requirement to use emergency arrangements.

Sellafield Ltd Incident Report – Holes in ductwork – 09 August 2021

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

As part of the improvement work, small holes were identified in ductwork outside the facility.

An assessment concluded that activity may have been released local to the duct. This is essentially historic in nature and was uncovered in a long-running programme of inspection and repair.

We have put in place some additional defence measures including enhanced monitoring systems in the area, and produced an improvement schedule that includes further repairs and additional containment provision.

There has been no harm to people and plant operations are unaffected.

Our regulators have been regularly updated on the duct and are fully aware of the current situation.

Sellafield Incident Report - Asbestos skip – 21 May 2021

An asbestos waste skip was delivered to the Sellafield site following processing off site. Unknown to site operators, the skip contained remnants of solid waste from a previous demolition project and a volume of aqueous waste. Whilst handling the skip the waste was released.

The subsequent investigation found that an estimated 3m3 of aqueous waste containing asbestos fibres entered the surface water drainage system where it was discharged via the factory sewer outfall.

To prevent reoccurrence, a tag system will be implemented to confirm that the skips are empty at the contractor’s off-site location prior to dispatch to the Sellafield site.

There was no safety impact and the Environment Agency has been informed.

Sellafield Ltd incident report - Potential gap in emergency arrangements - 28 April 2021

During inspection of the criticality detection system in the Magnox Reprocessing plant at Sellafield, a number of detectors were identified as not fit for purpose.

A review of the system was immediately initiated and a programme of work completed to address the issue which included repositioning a number of detectors.

There was no risk to our workforce or the community, and we have engaged with our regulators.

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).

Sellafield Ltd incident report – Chlorine levels – 18 January and 15 March 2021

On two occasions when water discharged from Sellafield’s Water Treatment Plant was spot sampled, the reported levels of chlorine were above the 0.30 milligrams per litre permitted limit.

In January 2021, the spot sample was 0.35 milligrams per litre and in March 2021 the spot sample was 0.50 milligrams per litre.

The follow up investigation has resulted in actions including an upgrade to equipment, instructions update and the required training.

There was no environmental impact as a result of these levels, and the Environment Agency has been informed.

Sellafield Incident Report – Consignments containing liquid – 9 March 2021

During processing of 2 consignments of redundant air filters at an offsite waste treatment facility, rainwater with trace activity levels was found in one of the sealed disposal bags used to pack the filters.

When the filters were repacked, approximately 80 litres of water was found in the disposal bag. Following investigation, it was discovered that the bag had been stored outside a waste handling compound at Sellafield prior to transport which resulted in rainwater building up within the bag. The water was subsequently safely disposed.

To prevent a reoccurrence, a secondary protection measure for the bags has been implemented and local procedures amended to reflect this change.

There was no safety or environmental impact and the regulator has been informed.

Sellafield Ltd incident report - Consignment of waste metals – 11 February 2021

A consignment of waste metals was despatched in an ISO freight container from the Sellafield site to an off-site metals recycling facility as part of a routine transfer.

Following receipt at the recycling facility, 2 banks of sealed, non-spill lead acid batteries were discovered among the waste metals. The batteries remained intact and undamaged.

The batteries were not declared on the inventory of the consignment and they are outside the standard waste acceptance criteria of the receiving facility.

There was no radiological or environmental impact and an investigation is being carried out to capture learning.

The regulator has been informed.

Sellafield Ltd incident report – Leak– 22 December 2020

A leak was identified on an inactive Sodium Hydroxide line, via a valve, during a transfer between the effluent plants services building and the Enhanced Actinide Removal Plant at the Sellafield site.

The leak, that was directed into a stainless-steel drip tray, overflowed and left the building and on discovery the transfer and the leak were stopped.

Two drains exterior to the building which discharge to a lagoon were subsequently sealed.

Also, a chemical binder was applied to the area to soak up the leak, and as a precautionary measure the lagoon pumps were stopped and additional samples taken. All samples returned within the normal range.

Sodium Hydroxide is a non radioactive chemical that is used to condition the effluent stream during this process.

There was no risk to our workforce or the community. We have engaged with our regulators.

Sellafield Ltd incident report - Construction waste misconsignment – 18 December 2020

A consignment of tarmac waste from the Sellafield site was inadvertently sent to an off-site location.

The consignment had not gone through our normal waste classification process.

We retrieved the waste at the earliest opportunity and work is ongoing to classify and dispose of it correctly.

Sellafield Ltd determined that there was no environmental impact and the Environment Agency has been informed. An investigation is underway.

Sellafield Ltd incident report – leak to ground – 9 September 2020

During a routine transfer of material between two adjacent tanks in the Thermal Denitration Plant on the Sellafield site, a quantity of uranyl nitrate liquor breached pipe work via a small perforation in the line.

The leak, that occurred within a controlled area of the site, was stopped within 20 minutes of it being discovered.

Sellafield Ltd has since replaced around 18 metres of pipework, and renewed the lagging and trace heating along approximately 120 metres of the pipe line.

There is no risk to our workforce or the community. We have engaged with our regulators.

Sellafield Ltd rated this event as an INES (International Nuclear and Radiological Event Scale) Level 1 (unauthorised release and degraded asset condition). This has now been confirmed by the United Kingdom INES National Officer.

Sellafield Ltd incident report - Chemical Incident – 11 August 2020

During a routine inspection of chemical substances stored on the Sellafield site, a small amount of chemicals were identified as requiring specialist disposal.

The organic peroxide, a chemical used routinely in industry, was in safe storage as part of our programme to identify and dispose of historic chemicals on site. During a routine investigation we noted that the chemical had changed state.

As a precautionary measure, a controlled evacuation of the Magnox Reprocessing Plant was carried out in order to investigate the chemical and devise the appropriate course of action. The plant was non-operational at the time.

In line with established procedures, support was requested from the Explosive Ordnance Disposal (EOD) team who safely disposed of the organic peroxide chemical package at the site.

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

Sellafield Ltd incident report - Sewage Treatment Works suspended solids - 22 July 2020

Daily results of suspended solids in the effluent discharged from the Sewage Treatment Works have been elevated during reduced occupancy on the Sellafield site due to COVID-19 since March 2020. The levels have now returned to normal.

The reduced occupancy has exacerbated known issues that are being dealt with through an improvement programme. The Environment Agency has been informed. There has been no measurable environmental impact as a result of these discharges.

Sellafield Ltd incident report - incorrect disposal of septic tank waste - 03 July 2020

It has been identified that the contents of a Sellafield Ltd septic tank, just outside the Sellafield site boundary, were collected and disposed through the foul sewer network on the main Sellafield site.

The installation permit does not allow for this waste generated outside of the site boundary to be brought on to site for disposal.

With immediate effect future waste will be disposed of at a suitable offsite facility.

There was no environmental impact and the Environment Agency has been informed.

Sellafield Ltd incident report - water level exceeded capacity - 18 June 2020

Water tank levels at an off-site water treatment plant exceeded capacity and a quantity of clean, raw water flowed down the engineered overflow line and discharged to controlled waters.

There was no environmental impact as a result of the overflow. The Environment Agency has been informed.

Sellafield Ltd incident report – leak to ground – 16 June 2020

An operator carrying out routine checks found that one of two auto samplers used to sample water collected in a lagoon at the Sellafield site was leaking liquid to ground.

The lagoon stores surface water from the Separation Area and processes water from other facilities prior to controlled release via the discharge pipeline to sea.

Reassurance monitoring has been carried out and there are no safety or environmental consequences as a result of this condition.

The auto samplers have been taken off line while work is being carried out to add a bunded area round the samplers to ensure there isn’t a recurrence of the incident.

A management investigation is underway.

Sellafield Ltd incident report - refrigerant loss – 11 June 2020

As part of routine maintenance of the Site Ion Exchange Effluent Plant chillers on the Sellafield site, that are used for cooling pond water, it was discovered that there had been a leak of refrigerant gas since the previous scheduled maintenance.

Repairs to the system were carried out in December 2019 following a similar incident.

The chillers have been taken off line and degassed while investigation work is carried to investigate why the leaked has recurred.

There was no risk to the public or workforce, and no radiological impact.

The regulator has been informed.

Sellafield Ltd incident report – electrical event – 24 April 2020

As reported on the Sellafield Ltd website on 24 April, during work to move an 11 Kilovolt (kV) Ring Main Unit (RMU) on the Sellafield site, an employee sustained injuries due to an arc flash.

The site emergency services attended and the individual was transferred to hospital with burns to the upper body. This is a specified injury under RIDDOR.

As a result of the arc flash some areas of the site experienced a power dip – all supplies were restored the same day of the event.

A number of the individual’s shift team were stood down on the day to ensure their health and welfare, and all non-emergency HV switching on site was suspended while an initial investigation was carried out.

There were no nuclear, security, radiological or environmental consequences, and a management investigation is underway to understand root causes.

Sellafield Ltd incident report - refrigerant loss – 18 December 2019

During maintenance of the Site Ion Exchange Effluent Plant chillers, used for cooling pond water, it was noticed that there had been a release of refrigerant gas over several months.

The leak has subsequently been repaired.

There was no risk to the public, the workforce or the environment, and the regulator has been informed.

Sellafield Ltd incident report – water level overflow - 18 November 2019

Water tank levels at an off-site water treatment plant exceeded capacity and a quantity of clean, raw water flowed down the engineered overflow line and discharged to controlled waters.

Investigation indicated that the water overflowed for around 90 minutes resulting in the discharge of approximately 100 m3 of water.

There was no environmental impact as a result of the overflow, but a permit breach is recorded as the discharged volume exceeded the permitted daily discharge limit of 60 m3 per day for the point of discharge.

The environment agency has been informed.

Sellafield Ltd incident report - sewage discharge - 17 November 2019

During routine plant checks, an operator reported that domestic raw sewage within a settlement tank was overflowing and discharging via the sewage treatment works outlet.

This is a release of suspended solids, which were being carried over the weir of the tank and discharged via the final effluent discharge channel.

Timely response and recovery has resulted in no adverse environmental impact. The regulator has been informed.

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 – implementation of operator instruction - 2 September 2019

A review was carried out following the transfer of filters from one area of a Sellafield building to another area of the same building.

This found an operator instruction had not been fully carried out during the transfer and that correct personal protective equipment had not been worn by some operators associated with the activity.

The task was carried out without incident, and there was no impact to the people, plant or the environment as a consequence.

Following the subsequent management investigation, the event was classified as an INES level 1 – (anomaly).

Sellafield Ltd incident report - personnel contamination event – 01 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 - 09 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 – 07 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 – 07 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 – 05 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 – 07 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 – 06 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 – 09 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 – 04 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 – 01 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 – 06 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 (https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/678296/Chemicals_disposal_investigation_report.pdf)

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 (http://www.onr.org.uk/sellafield-dfw.htm) and the Environment Agency (https://www.gov.uk/government/organisations/environment-agency).

Some of these reports are graded using the International Nuclear and Radiological Event Scale (INES). (https://www.iaea.org/topics/emergency-preparedness-and-response-epr/international-nuclear-radiological-event-scale-ines)

See details of incidents at Sellafield before 1 August 2017 (http://webarchive.nationalarchives.gov.uk/20170712122957tf_/http://www.sellafieldsites.com/press-office/incident-reports/)