LLWR’s application to vary its Environmental Permit to allow continued disposal of radioactive waste at the repository was submitted in October 2013. The application was supported by an Environmental Safety Case (ESC) submitted in May 2011.

In its ‘Guidance on Requirements for Authorisation’, the Environment Agency defines an Environmental Safety Case as “a set of claims concerning the environmental safety of disposals of solid radioactive waste, substantiated by a structured collection of arguments and evidence.”

The objective of LLWR’s ESC is to demonstrate to the Environment Agency and other stakeholders that it is safe to continue to dispose of low level waste at the Repository.

The extended operational lifetime of the facility, the continued disposal of waste into future vaults and the subsequent closure and capping of the LLWR, were dependent upon the approval of the ESC by the Agency.

This rigorous document considered environmental safety now and up to thousands of years in the future.

Over 80 technical experts were involved in its production, and it took 85 man years of work to develop. It comprise 2,000 pages and is made up of 17 reports and a non-technical summary. A further 100 underpinning reports make up a further 10,000 pages.

Geology, hydrogeology, waste characterisation, waste processing, engineering of the waste vaults, potential radiological impacts, coastal erosion and engagement with stakeholders are among issues examined in detail in the ESC.

The ESC submitted in 2002 had not fully met the Environment Agency’s requirements, so when it issued the LLWR with an authorisation (now called a permit) in 2006, it only allowed disposal of low level waste in Vault 8 stacked up to the equivalent of four ISO containers.

The subsequently constructed Vault 9, although designed and built to meet disposal criteria, was authorised for storage only. A revised or new permit was required for LLWR to be allowed to dispose of waste in Vault 9 and future vaults.

The Agency completed a detailed review of the 2011 Safety Case and consulted on the application from November 2013 to February 2014.

During the review, LLWR responded to 72 Issue Resolution Forms – formal questions – from the Agency.

A further consultation on the draft decision and a draft environmental permit, in which the Agency proposed to grant the permit, took place from May to July 2015.

On 1st November 2015, the revised permit became effective, achieving a key objective of the NDA when awarding the new contract for managing LLWR in 2008.

The 2011 ESC demonstrated that it was safe to continue to dispose of LLW at the repository now and into the future.

Yet that’s not the end of the story. The ESC is on ongoing project. LLWR’s Environmental Permit requires us to submit an updated ESC to the Environment Agency by 3/5/2021. The organisation’s ESC team of six, supported by several contractors, has already started work on planning the next ESC.

The ESC influences many areas of the company. LLWR has a site Environmental Clearance Certificate that reflects ESC requirements and ensures that the Repository is managed in a way that is consistent with the assumptions and results of the ESC.

Waste Acceptance Criteria also reflect the ESC to ensure that we only accept waste for disposal that is consistent with the assumptions in the ESC. It also influences the Repository Development Programme as any future site work will have to be consistent with assumptions in the ESC.

 2011 ESC Non-technical Summary

2011 ESC Level 1 Main Report

2011 ESC Level 2 Reports

 Peer Review

Research and Development



 Near Field



Site Evolution



Previous Assessments

Asessment Process

Assessment Approach


Assessment of an Extended Disposal Area

Waste Acceptance

Environment Agency Review Documentation

Annual Review Documentation

Permit Application Documentation

Further ESC Documentation