Silo Emptying Plant (SEP) main machine build completed ahead of schedule

24 February, 2014

Nuclear Engineering Services (NES) was pleased to welcome Chris Halliwell, Head of Programme for MSSS and Alan Haile, Head of Project for MSSS Retrievals, together with other Sellafield Ltd colleagues to the Wolverhampton facility on completion of the main machine build (MMB) milestone for SEP 1. This completes the build of both SEP 1 and SEP 2 mobile caves. NES has been working on the design and build phase of this project since 2011 and has overcome significant challenges to deliver the project.

Designed for use at Sellafield Ltd site, the mobile caves will be used to retrieve Intermediate Level Waste (ILW) from 22 vertical silos containing Magnox swarf and miscellaneous beta gamma wastes (MBGW). Weighing approximately 400 tonnes each, and assembled from over 13,500 parts each, the caves operate on a rail system and remove wastes via a hydraulic grab and tooling system through an import/export tunnel sited on the top of the waste silos.

Learning from experience gained from the completion of SEP 2, the first machine to be built as part of the Sellafield Ltd and NDA contract, included:

Parallel purchasing of critical and long lead items in the supply chain together with early engagement of the supply chain during design reviews, particularly on large subcontract orders.

NES introduced an improved on-site document control system (drawings, installation and termination sheets) to ensure control of drawing issue on both the cabling and pipe work systems and employed a more rigorous tracking of outstanding document operations.

Patrol inspectors were used during the build phase leading to improved quality assurance. Waste caused during terminations was captured by a bagging system to alleviate foreign material being introduced.

Increased visual management such as outstanding items, health and safety awareness and quality management contributed to improve quality issues.

The teams from Sellafield Ltd and NES have worked together to address the challenges of accelerated and compressed design, procurement and assembly phases, with frequent and consistent communication lines for project reporting. NES adopted a flexible working regime that included working around the clock, where necessary, to ensure that quality and programme standards were maintained at all times. The strategy driving this was to ensure areas of the build were not left for long periods of time awaiting issue resolution or clarifications, mitigating potential schedule delay.

Mike Hawe, NES Managing Director, comments:

“We are delighted to announce completion of this significant milestone for what is undoubtedly one of the most complex decommissioning programmes in the world. NES has consistently demonstrated the skills and capability to deliver to unique and complex requirements.”

Chris Halliwell, Head of Programme for MSSS, comments:

“Decommissioning the Magnox Swarf Storage Silo is a key priority for Sellafield Ltd and we’re investing a substantial budget in the complex technology to retrieve nuclear waste from this legacy store. We’re under pressure to both accelerate the waste retrievals programme to reduce the risk and hazard posed by the historic waste and to provide value for money for the UK taxpayers. We are reliant on specialist suppliers such as NES to meet these objectives and we’ve worked closely with them to achieve this latest milestone. This is a significant achievement, however there’s much work to be done before we’re actually retrieving nuclear waste from the silos – my eyes are firmly focused on getting the waste out sooner rather than later to meet the Nuclear Decommissioning Authority’s (NDA) requirements.”

Work will now move to preparation for test and commissioning, maintenance demonstrations and integration of off-board equipment.