Operational Risk Management (Dynamic ALARP)

Introduction

It is a legal responsibility for the licensee to maintain the overall safety risk presented to workers, the public and the environment, arising from any potential nuclear fault and accident, to be As Low As Reasonably Practicable (ALARP). The requirement to be ALARP is implicit within the nuclear site licence, and the licensee is obliged to demonstrate how this is achieved aligned to Office for Nuclear Regulation (ONR) guidance (NS-TAST-GD-005).

Demonstration of ALARP is the responsibility of the licensee design authority (NS-TAST-GD-079).

Historically, the overall status of nuclear safety risk has been determined to be tolerable and ALARP as a result of combined evidence presented in the deterministic and probabilistic safety assessments. The overall ALARP position has also been provided by the periodic safety review (NS-TAST-GD-050). An acceptably maintained risk status is required at each Nuclear Power Plant (NPP), and possibly across a fleet of NPP, requiring a consistent approach to the management of nuclear safety. This is a continuous activity, hence the term dynamic ALARP.

Dynamic ALARP in Practice

The application of dynamic ALARP requires the prioritisation and management of work and resources to mitigate the overall risk, and to ensure that all reasonable measures are implemented and timescales are commensurate with the nuclear safety risk.

Licensees will develop and implement their own management systems, arrangements and processes to enable the management of work, with many processes combining to determine work prioritisation and delivery. The management systems necessary to support dynamic ALARP include, but are not limited to, the following management system processes.

• Design Safety Assurance.
• Management of Engineering.
• Risk Management.
• Management of Work.
• Asset Management.
• Business and Investment Planning.

The overall ALARP risk status of the NPP is continually influenced by changes to the operating environment which may include physical changes to plant, changes to process, or changes to guidance and standards. The way the company responds to operating environment changes via allocation of their finite resource, determines how well the ALARP risk status is managed.

The dynamic ALARP claim is therefore that continuous, or dynamic, management and prioritisation of work maintains the overall nuclear safety risk to be ALARP.

A simplified dynamic risk ALARP process is shown in Figure 1.

Additional Information & Guidance

• ONR, NS-TAST-GD-005, Guidance on the Demonstration of ALARP (As Low As Reasonably Practicable), December 2019.
• ONR, NS-TAST-GD-079, Licensee Design Authority Capability, April 2019.
• ONR, NS-TAST-GD-050, Periodic Review of Safety (PSR), July 2017.