Annual Report for 2010/11 and Forward Programme - Sellafield Ltd

SSEM/2011/4730 June 20116. Aims and Objectives6.1 Introducing the requirement for large area beach monitoringThe 2008 Summary Report (Hemming, 2008) provides details on some of the backgroundand drivers that led to the introduction of a regulatory requirement for large area beachmonitoring at Sellafield. The report also sets out how the early programme for beachmonitoring developed.In brief, the detection, recovery and analysis of a particle containing 90 Sr, during routinemonitoring of the strandline on Sellafield beach in 2003, triggered a review of beachmonitoring operations. This review and subsequent trial of a vehicle mounted system in late2006 / early 2007 resulted in an evolving programme that has seen the development anddeployment of state-of-the-art detection equipment across a wide extent of the beaches onthe coast of West Cumbria.During the early programme, it was not known whether radioactive particles were present insignificant numbers and over what geographical range. Based on early modelling work, thefirst trials took place in areas where the highest chance of encounter had been predicted, tothe immediate north of the Sellafield site. As material was detected and recovered from thislocation; so the programme started to include beach areas that are more distant from theSellafield site. This has resulted in monitoring being carried out on sections of all the mainstretches of accessible beach along the West Cumbrian coast; and has included beaches onthe north Solway.Consistent with the aim of understanding the geographic range and distribution of particlenumbers, the specified area to be monitored increased as the programme developed. TheSellafield trial covered an area of 9.2 ha, followed by a 26 ha trial at Braystones (usingvehicle-mounted and hand-held equipment). The success of the trials led to the inclusion ofa specification in the Compilation of Environment Agency Requirements (CEAR) requiring “aminimum beach area of 15 ha …by 31 July 2007, with a minimum area of 100 ha to besurveyed by 31 March 2008”. In fact, the total area monitored during 2007/08 was in excessof 150 ha, against a revised specified area of 146.7 ha.Success in achieving what may be described as arbitrary target areas, effectively led to abeach monitoring programme of 250 ha per year. Year-on-year, the total area coverageactually achieved has exceeded the target, with last year’s coverage area totalling c.319 ha.These totals are corrected to take account of the overlap that is built into the vehiclemonitoring swathes to ensure that contiguous coverage is achieved. The specified area formonitoring has essentially evolved based on operational performance, as determined by therequired detection capability of the equipment; the natural constraints presented by work in abeach environment (beach accessibility, beach substrate, tidal window, available daylightetc); and the priority given to public protection and assurance. SL considers that 250 ha peryear represents the working capacity of the current system (Softrak running Synergy at1m/s), allowing for minimum down-time periods for vehicle maintenance and buffer time.6.2 Beach monitoring programme reviewThe early specification for Sellafield beach monitoring was heavily influenced by the workbeing done at Dounreay, where fragments of fuel are being detected in the environment. Asthe Sellafield programme has evolved it has become evident that the situation at Sellafield issufficiently different to that at Dounreay; and presents a number of unique challenges,including the types and relative distribution of contaminated material. As a consequence the© Nuclear Decommissioning Authority 2011. 84