E23 Additional nitrogen supply


Historically, a single bulk nitrogen tank supplied the centrifuge enrichment plant on the Capenhurst site with its requirements for gaseous and liquid nitrogen.

It was identified as being the only permanent gaseous supply available to the plant and therefore presented a potential single point of failure. The original system was installed circa 1997 and was coming to the end of its operational life.

A specialist supplier was identified to provide a new system incorporating two tanks and associated equipment in an on-line and stand-by system configuration. Tenet was tasked with providing design capability that conformed to the latest British standards and Client equivalent documentation.

Services Provided

Tenet’s design team were responsible for producing comprehensive General Arrangement drawings, panel layouts, Single Line Diagrams, wiring diagrams, cable routing drawings, drawing schedule and termination schedule.

  • Temporary lighting and small power distribution to facilitate installation works;
  • Final mains power installation to supply the new nitrogen supply system;
  • Permanent and emergency lighting of the external enclosure;
  • Lightning protection and earthing arrangements

Development of a scheme design for interfacing to the Ethiopian National Grid.

  • Selection and position of the luminaires;
  • Position of the lighting circuit switches;
  • Cable containment routes;
  • New lighting control panel;
  • Sub-main power distribution to new lighting control panel;
  • Emergency lighting to illuminate escape route from building and around concrete pads.

A schematic was also produced containing information on the lighting circuits, cable sizes and cable types to be used. The selection process was driven by the output of the lighting design carried out using the Dialux software package. Cable calculations were completed on Amtech, with independent


checking and verification. All drawings were produced on the most appropriate AutoCAD programme to ensure compatibility with the client’s requirements.

In addition to the design drawings a document was produced in the form of an Operations & Maintenance (O&M) manual, which contained the following information:

  • Method of installation;
  • Materials list for construction;
  • Distribution board schedule;
  • Luminaire data sheets;
  • Cable calculations.


The client required the work to be carried out on a fixed price basis and aligned to agreed delivery milestones.

The Tenet design team had to quickly appraise themselves with the contents of the tender specification and scope of work documents and engage in early dialogue with key stakeholders.  Tenet’s familiarity of the Capenhurst site and in-depth knowledge of implementing UUK procedures and standards enabled this to be conducted quickly and efficiently.

Since the project scope encompassed design of both temporary and permanent lighting and power distribution installations, it was important to have a clear and comprehensive understanding of the location and environment in which the new nitrogen system was to be installed. This required conducting extensive site survey activities and working with the client to ensure that the plan and elevation drawings of the plot were as accurate as possible. Tenet was able to accurately identify the location of key existing equipment, power supplies, cable runs and containment methodology, which prevented the need for any further rework to the design impacting cost or schedule.

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Due to our previous experience of working on the Capenhurst site and adhering to UUK standards, the Tenet design team were able to quickly understand project requirements and produce deliverables needed to form a comprehensive design package.

This was developed to a level where the design could be handed over to a third party to procure necessary equipment and carry out installation works without any prior knowledge of the project. This provided the client with the flexibility to place the next phase of the project on hold indefinitely until such time that suitable funds were made available to progress.

Due to our ability to deliver high quality design services to cost and to schedule, Tenet were subsequently awarded a direct engineering design framework agreement. With this contract in place, we are able to support client in managing the EC&I design elements of further asset care, plant life extension, process improvement and building infrastructure modification projects. This was promoted by positive customer feedback from the Capenhurst project management community.

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