The UK Environment Agency (EA) has written to the Drigg Low Level Waste Repository (LLWR) in Cumbria with concerns about a delay in securing waste at the site, the BBC has reported. Nuclear Waste Services (NWS), which operates Drigg, said the delays did not impact the surrounding area and that they had taken the time to ensure the right solutions were created for the safe disposal of nuclear waste.

The letter, written by the EA in January, and obtained by the BBC through a Freedom of Information request, sets new conditions that LLWR must meet. LLWR had failed to make sufficient progress on operations to secure the radioactive waste through a process known as capping and so had breached the terms of its environmental permit.

NWS Chief Operating Officer Martin Walkingshaw explained: "Placing the engineered cap over the legacy radioactive waste disposal facilities at the UK’s LLWR is a first of its kind activity for the UK." He confirmed that NWS and EA were consulting on progress.

"Capping is a key part of the disposal, and we are currently implementing the required design by procuring, importing and emplacing thousands of tonnes of capping materials in line with our planning conditions and stringent quality requirements," he said.

EA also told LLWR it had failed to meet a deadline for a previously imposed improvement condition, regarding a request for a written plan to protect waste in certain areas, including capping one of them. While the plan was delivered, there were delays in implementing it. While 2028 had been agreed as an initial date for completion, discussions are now under way to extend the deadline as LLWR believes more time is needed.

NWS said the delays were caused by issues with the design of the engineered cap. "Throughout the design phase a number of assumptions were tested, as is common practice. Not all of these assumptions held true, and one in particular, caused a significant change in design."

The LLWR was established in 1959 and is the only disposal site that is licensed by Office of Nuclear Regulation (ONR) in the UK. The site accepts low-level radioactive waste from all over the country and disposes of it in a way that protects people and the environment. The waste is disposed of in engineered concrete vaults and where possible the waste is treated, containerised and grouted before placement in the vault. ONR says more than £100m ($123.5m) has been invested in the infrastructure of the site over the past decade to maintain the facility.

In January 2022, as part of the Nuclear Decommissioning Authority’s (NDA’s) plans to bring together the UK’s leading nuclear waste management capabilities into a single organisation, LLWR along with Radioactive Waste Management (responsible for deep geological disposal) and the NDA group’s Integrated Waste Management Programme, came together to form NWS.

ONR’s last inspection of LLWR is dated August 2023 and was given a “green” rating. ONR undertook the inspection to examine LLWR’s physical arrangements for controlling exposure to ionising radiations from the site to members of the public. The LLWR nuclear licensed site was selected for inspection for the following reasons:

  • The last inspection of LLWR was undertaken in January 2015;
  • LLWR is one of four licensed sites which has a radiation dose rate to the most exposed member of the public above the ONR Safety Assessment Principle Target 3 Basic Safety Objective of 0.020 mSv;
  • From 2020 to 2022 there had been an upward increase in radiation dose rate to the most exposed member of the public.

The inspection was conducted through “discussions with key licensee personnel, the sampling of licensee documentation and a site perimeter fence walk-down”. The conclusion of the inspection was that “LLWR had taken adequate steps to reduce doses to the public from the site waste operations”.

The inspection concluded that the number and location of the thermoluminescent dosimeters (TLSs) that monitor radiation dose in relation to properties outside the site perimeter fence were adequate. “The number of waste containers being received by the site has reduced by one order of magnitude, reducing the number of on-site transportation doses from the site. LLWR have placed adequate mobile concrete shielding between the Vault 8 and the site perimeter fence to reduce doses to members of the public off-site.” LLWR implementation of regulation arrangements were judged to be “adequate to reduce doses to the public from the site waste operations in the areas inspected”.

Image: The Drigg Low Level Waste Repository in Cumbria