Case Study // Bradwell Power Station – Nuclear

History

Following defuelling in the summer of 2005 and the Nuclear Power Station’s shutdown in March 2002, the demolition and bulk asbestos removal project came to an end, bringing down the curtain after 40 years of Bradwell’s operation.

The station generated nearly 60 TWh of electricity during its operational life and on a typical day would supply enough electricity to meet the needs of three towns the size of Chelmsford, Colchester and Southend combined. The Turbine Hall which was constructed back in the 60’s spanned the same diameter as 3 standard size football pitches, with operational life now a thing of the past the Power Station now acts as a pilot project for a series of 10 further power stations to be demolished by Magnox Ltd.

Scope

The Project consisted of a number of structures, each with their own construction method and unique challenges. These included the Main and Auxiliary Turbine Halls, a Steam Annexe, a Battery Building, Convertor Building, Main Control Block, Water Treatment Plant and associated support buildings. Constructed in the late 1950’s, the site was essentially bounded to the east by two Magnox nuclear reactors, to the north by the River Blackwater estuary, to the west by farmland and to the south occupied offices and workshops.

Deplant

As areas of buildings were released, de-planting of the former plant installations commenced with Erith employing hand, hydraulic, mechanical and hot working techniques to dismantle the structures, to maximise re-cycling returns and ensure Erith provided best value to our client.

Overhead gantry cranes were recommissioned and proved vital in maintaining safety and programme during this phase. Erith removed a number of plant items, including 130te stator units, 45te steam beds and 62te condenser units.

Demolition

The demolition of the structures was carried out to an Erith designed sequence of de-construction using high reach and conventional excavators, safely working hand in hand with hot working techniques. The buildings varied widely in their own specific construction methods and presented differing considerations for the site team. Each structure had its own SSoW (Safe System of Working) written which would explicitly detail the method of demolition and plant required.

This would be assessed by up to 14 Magnox staff and then the work commenced. Erith completed the structural demolition of the site two months ahead of our baseline programme, with the client instructing further demolition works during this phase.

Innovation

The Bradwell site has become the first in the UK to use a ‘freeze dredging’ process, developed in conjunction with FriGeo of Sweden, to remove sludge from the site’s used fuel storage pool.

The process works by freezing small amounts of waste whilst the equipment is submerged in the pond water. The frozen mass is then thawed to separate out the sludge and debris. The process of thawing and dewatering reduces the moisture content of the contaminated materials, thereby minimising waste volumes. The system allows the team operating the machinery to work remotely from the pool area, with the help of cameras and hoists, resulting in a much lower radiological hazard working environment.

Project Goals

  • 125,000 man hours without a loss time accident
  • Project completed 2 months ahead of programme
  • 96% of demolition arisings recycled in-house

“It was one of the most enjoyable projects I have worked on. Contractors Erith, who carried out the work, are a good contractor to work with and I am so pleased to have delivered such a significant project successfully, and with a wonderful team to make it happen.”

Graham Cotton – Magnox Project Manager