Box Encapsulation Plant (BEP), Sellafield

RPS is providing a variety of safety support for the upgrade and fit-out of the Sellafield Box Encapsulation Plant (BEP) building. Once complete the building will be used to safely process and store nuclear waste retrieved from various legacy ponds and silos around the Sellafield site.

The project comprises the engineering design to meet the new required purpose, construction and installation activities, followed by inactive and active commissioning. RPS is working as part of a consortium to deliver the project, including Jacobs, Balfour Beatty and Wood Group.

Key details

Project name
Box Encapsulation Plant (BEP)

Sellafield Limited

Cumbria, UK

Services provided

  • Radiological assessments
  • Shielding assessments
  • Human Factors assessments
  • Fire assessments
  • Construction safety support


The legacy ponds and silos on the Sellafield site collectively present the highest risk to workers and the public in Northern Europe. The Sellafield mission is to reduce the hazard from these facilities as soon as possible. The BEP is crucial to this process; allowing processing of the waste and its subsequent safe storage.

The challenge is to deliver the modified BEP to meet the tight timeframes driven by the retrievals operations. The design of the facility must be robust, fault tolerant and simple to allow throughput to be maximised, thereby enabling high hazard risk reduction.

The design and operation of the BEP must meet all Nuclear Site License Conditions and demonstrate compliance to the Office of Nuclear Regulation (ONR) to receive the relevant permission to start active commissioning.

BEP - project image.png


To meet the challenges, we have provided a variety of services and integrated our personnel into the BEP project team. These include:

  • HAZOPs to evaluate process and mechanical systems for deviations that may result in hazards or operability issues.
  • Radiological safety assessments to evaluate the risks from processing nuclear material and to specify safety systems required.
  • An electronic Interactive Safety Case (eISC) that allows for the claims, arguments and evidence to be easily identified, tracked and interrogated.
  • Hazards of Construction Studies (HAZCON) to ensure that the hazards from construction activities are recognised.
  • Conventional fire assessments to ensure the building complies with Approved Document B.

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