Sellafield Ltd has reported today that the site’s HLW waste Evaporator ‘B’ has had to be taken out of service because of yet another failure of one its internal cooling coils. Under normal circumstances, the process of evaporating the liquid HLW produced by Sellafield’s THORP and Magnox reprocessing plant would be transferred to the site’s two other Evaporators A and C.
Neither Evaporator A or C however are currently available for use – leaving the Sellafield site with no way of processing (condensing) any HLW prior to its transfer to the Vitrification Plant for conversion to a solid glass form. By way of lucky coincidence for Sellafield, both reprocessing plant are also currently out of action – THORP having closed in July (for an engineering overhaul of its own newer Evaporator C) and Magnox being closed down, somewhat suspiciously, ‘for routine engineering not long before the Evaporator B failure’.
In a rehash of a similar episode earlier this year, raised levels of radioactivity were detected some days ago within the 50-year old Evaporator B and, following its automatic shut down, a small corrosion hole was discovered in the top inner cooling coil of the Evaporator. Commenting to the media today, Sellafield Ltd has said that it is planned to isolate the failed coil to enable the Evaporator to be returned to service. Having already lost two of its original four cooling coils through corrosion, the loss of the third coil reported today means that once returned to service Evaporator B must operate on just one coil – a quarter of its original coil complement – the final back-up being the external cooling jacket which covers the base and sides of the Evaporator.
Whilst acknowledging today that further cooling coil failures are expected because of the age of the evaporators and the harsh internal environment to which they are subjected (hot nitric acid), Sellafield Ltd has said that the site’s current loss of all 3 working evaporators ‘will have no impact on operations’. This short term and heavily spun appraisal obscures however the real problems associated with today’s failure which puts future reprocessing schedules, already years behind schedule, in jeopardy in the mid term. When operating, both reprocessing plant will be wholly dependent on the ability of the three Evaporators A, B & C over the next five years to deal with the HLW produced during reprocessing operations, as well as wastes from the Vitrification plant. A new facility Evaporator D, now costing in excess of £200M, is not expected to come on line until at least 2014.
Having now lost three of its original four cooling coils, Sellafield will be concerned that Evaporator B will suffer the same fate as its sister facility Evaporator A which, also down to one cooling coil, has been sidelined for many months and is reserved for emergency use only. Despite this, it is understood that Evaporator A, is now expected to be pressed into service again at some point before the end of 2009 when Magnox reprocessing is scheduled to restart. Once back in operation, both Evaporators A & B are likely to limp along at a reduced rate until Spring next year when THORP’s Evaporator C is returned to service and in a position to assist in the site’s vital evaporation requirements.
Once Evaporator C returns to service next year, THORP reprocessing is expected to re-start – and then to complete all its contracts by around 2016/17. The Magnox plant is scheduled to complete its work by 2016. The bringing on line of Evaporator D in 2014, and the reliable operation of A, B & C in the interim, is crucial to these completion dates being met.
For further detail see CORE Press Releases of 18th May and 3rd June 2009 on www.corecumbria.co.uk