What is it?

All facilities and activities in the UK that use, process, handle or store sufficient quantities of radiological material are required to have a site licence to operate. One of the conditions of which is that the Licence Holder (the licensee) has adequate arrangements in place for the production and assessment of nuclear safety cases.


A nuclear safety case is the totality of the documentation that presents the arguments and evidence to justify that a facility or activity can be operated safely. It is required to be maintained live throughout the full lifecycle of the plant or facility, from concept design, through construction, commissioning, operation and, ultimately, decommissioning.


The safety case can range from a single document justifying a relatively simple activity or modification to thousands of documents presenting all of the safety assessment, supporting analysis and evidence justifying the safe operation of a nuclear reactor.


The output of the safety case defines the safe operating envelope of plant or activity, identifying the limits and conditions that must be maintained to ensure nuclear safety.

Why is it important?

There is a requirement for all Nuclear Licence Sites and other facilities that pose a risk of release of radiation to the public or workers to possess and maintain a valid safety case.


The primary purpose of the safety case is to enable the licensee to satisfy themselves that they fully understand the potential risks associated with their facilities and operations and have implemented suitable and sufficient safety measures to prevent, protect against and mitigate faults to ensure that the risks are adequately managed. This is achieved by demonstrating that the risk of a radiological release has been reduced to a level which is as low as reasonably practicable (ALARP).


The safety case is also the vehicle by which the licensee can demonstrate to the Regulator that they are adequately managing the safety of their facilities and processes, in accordance with their own arrangements and the requirements of their site licence.

What do we do?

CRA have a team of nuclear safety case specialists who are experienced in the provision of safety and assurance services to clients across the UK civil and defence nuclear sectors, as well as internationally.

Our experts utilise both deterministic and probabilistic techniques to produce high quality, proportionate and fit for purpose safety assessments to meet our clients specific requirements. Our capability spans the full project / plant lifecycle, from concept design and development to decommissioning and waste management, including:

Hazard Identification and Assessment – including Hazard Identification studies, Hazard and Operability (HAZOP) Studies, Failure Modes and Effects Analysis (FMEA) etc.

Safety case authoring, verification and independent assessment – production of safety case documentation and provision of support to all stages of the review and approval process.

Development of safety management arrangements, including safety case process and guidance documentation.

Development and delivery of training.

Fault Studies and nuclear physics support to existing generation and new build facilities.

Optioneering and ALARP workshops – facilitation and expert involvement in options development, assessment and selection.

Fault and Engineering Schedule development, including the use of databases and other electronic tools.

Risk informed decision making utilising the Probabilistic Safety Assessment.

Provision of expert support to regulatory bodies.

Periodic Safety Reviews – specification and delivery of periodic safety reviews for civil and defence clients.

Radwaste and decommissioning – waste characterisation, defuelling studies, decommissioning safety cases etc.

Safety support to fusion facilities.


Our safety case specialists are also able to work closely with our Probabilistic Safety Assessment and Human Factors teams to provide a fully integrated service that we believe is unique within the UK nuclear sector.

Our capability statements describe each of our Safety Case services.

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