Babcock project gets Oldbury nuclear reactors back online
28 Jan 2010
London – For the first time in several years, both of Oldbury’s reactors are fully operational and generating 400MW of electricity each day. The Oldbury site, which is operated by Magnox North on behalf of the Nuclear Decommissioning Authority (NDA), began working with the regulators several years ago to demonstrate the structural integrity of the graphite in the longest operating irradiated graphite core in the world.
With the support of the NDA, Oldbury sought permission to operate the station for a further two years, consequently a considerable programme of work needed to be undertaken. A condition of extended generation was the need to install an additional system, to complement the existing reactor safety systems, that would provide an extra alert should there be any concerns about the integrity of the fuel cans inside the reactor cores.
Babcock Nuclear Division, part of Babcock International Group, was asked to design and manufacture a fuel integrity monitoring system (FIMS), which was installed by Magnox North and is now in the final stages of commissioning. The system taps into the cooling CO2 flow that is already diverted by one of the existing safety systems, the Burst Can Detection System, which uses it to continually monitor the integrity of the fuel.
“The timing of FIMS has been crucial and it is unusual for a major system such as this to be installed in under a year,” said Adrian Mitchell, generation optimisation programme manager at Oldbury. In addition, he noted, “the seismic qualification of the new system is stringent and has naturally had to be supported by extensive documentation.”
The company had previously provided a similar system for Hinkley Point and was confident that it could be developed to meet Oldbury’s specific requirements, added Piers Wood, Babcock’s FIMS programme manager at Oldbury. The equipment, he said, taps into Oldbury’s existing reactor safety system, the Burst Can Detection system, by taking a sample of the CO2 reactor gas that is monitored to ensure fuel integrity.
“Essentially, we divert some of this gas, bulk it together and pass it over a radiation detector, which is set to check for some very specific isotopes,” said Wood. “If we find these isotopes an alarm sounds. However, the complication is that we collect it from three different channels and the alarm sounds if two of them have the telltale radiation signature.
“Therefore, for the system to work accurately, all the pipe work leading to the FIMS monitoring cabinets has to be exactly the same length. Naturally, in reality, the distance between the sampling points and the measuring points varies, so we had to design pipe runs that made the distances identical. The monitoring is constant, so essentially, FIMS looks for change.”
The FIMS contract was worth £2 million to Babcock. The company began work on FIMS in April 2008 and the majority of the equipment was delivered in January 2009 in accordance with an accelerated programme. Installation of the equipment was completed by March 2009.
