Babcock completes Dungeness overhaul

London - Babcock has completed an overhaul of the reactor gas circulators as part of a major outage at EDF Energy’s Dungeness B power station, which was brought back on line in early June.

The ouiage programme is planned every three years at each of the reactors at Dungeness B. Babcock worked with EDF Energy personnel and alongside contractors such as Doosan which undertook similar programmes to overhaul the boilers.

According to Babcosk, over 100 of its personnel were on site to undertake the project, which involved the maintenance of rotating plant including gearboxes, clutch assemblies, motors and cartridge units on the gas circulators, for which Babcock is the original equipment manufacturer.

The Babcock site team fully stripped two of the circulators down to their component parts (using dedicated lifting equipment), and inspected the equipment for wear. The main motors and pony motors driving the circulators were removed and sent off-site for specialist maintenance.

All affected gaskets and sealing arrangements were replaced in a leak mitigation project to minimise oil leaks. Two other gas circulators were visually inspected and tested to confirm that they were working satisfactorily.

A further partial stripdown of another gas circulator involving a full penetration tube strip down to replace the running seal was also undertaken before the start of the main outage by a Babcock team mobilised in advance. This allowed the other reactor to be brought up to full power at the end of March 2012.

Babcock is also the fuel route contractor for Dungeness B power station, based on the company’s extensive knowledge of fuel route design. In this role, Babcock maintains a full-time team of some 40 people year-round on site. They working alongside EDF Energy staff to optimise the fuel handling within the station to maximise power generation, by maintaining and modifying key items of equipment, such as the fuel handling machine.

Babcock’s delivery of this project, included the procurement of new equipment such as a cantilever lifting beam and the development of a trolley to remove the shield block, rather than bringing a mobile crane to site. This, it said, saved several days on the critical path of the outage, as well as reducing direct costs.

“The close working relationship between Babcock and EDF Energy has been key to successfully completing all planned works on this outage to quality and ahead of schedule,” said Sue Shaw, Babcock business manager.

(Picture caption: the new gas circulator pony motor lifting beam in action. The counterbalanced beam was designed and manufactured by Babcock to allow the pony motor to be lifted out safely for refurbishment, in a restricted space).