Radioactivity in Food and the Environment, 2014
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RIFE - 20 Radioactivity in Food and the Environment, 2014 2015 5. Defence establishments This section considers the results of monitoring by the Environment Agency, FSA and SEPA undertaken routinely Key points near nine defence-related establishments in the UK. In • Total doses for the representative person addition, the MoD makes arrangements for monitoring at were similar to or less than 1 per cent of the other defence sites where contamination may occur. The dose limit at all those sites assessed except operator at the Atomic Weapons Establishment (AWE) at Barrow where the effects of historical in Berkshire carries out environmental monitoring to discharges from Sellafield were apparent determine the effects from low level gaseous discharges • Discharges, environmental concentrations at its sites. Monitoring at nuclear submarine berths is and dose rates in 2014 were broadly similar to also conducted by the MoD (DSTL Radiological Protection those in 2013 at all establishments Services, 2013). Barrow, Cumbria The medium-term trends in doses, discharges and • Total dose for the representative person was environmental concentrations at Aldermaston, Devonport, 6 per cent of the dose limit but dominated by Faslane and Coulport, and Rosyth have been considered effects from Sellafield in a summary report (Environment Agency, FSA, NIEA and SEPA, 2010b). 0.5 per cent of the dose limit. The representative person 5.1 Aldermaston, Berkshire was an infant consuming local cows’ milk at high-rates. AWE at Source specific assessments for high-rate consumers of Site Aldermaston locally grown foods, for sewage workers and for anglers, provides and give exposures that were also less than 0.005 mSv in maintains the 2014 (Table 5.1). Estimates of activity concentrations R. Thames fundamental in fish have been based on shellfish samples from the Pangbourne R dingea components of the aquatic monitoring programme for dose determination, UK’s nuclear and for anglers the assessment has conservatively included Burghfield R. Kennett deterrent (Trident). consumption of fish at a low rate of 1 kg per year. The site and facilities at AldermastonAldermaston Aldermaston remain Gaseous discharges and terrestrial in Government monitoring ownership under a Government Owned Contractor Operator (GOCO) Gaseous radioactive waste is discharged via stacks on the arrangement. The day-to-day operations and the site. Discharges in 2014 were generally similar to those maintenance of Britain’s nuclear stockpile are managed, on reported in 2013. Samples of milk, terrestrial foodstuffs, behalf of the MoD, by AWE plc. The site is regulated by grass and soil were taken from locations close to the site the Environment Agency to discharge low concentrations (Figure 3.4). Activity concentrations in milk and foodstuffs of radioactive waste to the environment. The most recent (Table 5.2(a)) were generally below the limits of detection, discharge permit was issued in 2012. as in 2013. The tritium concentrations in milk, foodstuffs, grass and soil are reported as less than values in 2014. A habits survey has been conducted to determine the Tritium is considered in the dose assessment and is of consumption and occupancy rates by members of the very low significance. In soil samples, where comparisons public in the vicinity of the site (Ly et al., 2012). Data for can be drawn at the same location, concentrations of consumption, handling and occupancy rates are provided caesium-137 were similar to values in 2013. Levels of in Appendix 1 (Table X2.2). uranium isotopes also remained similar to 2013. Natural background or weapon test fallout would have made a significant contribution to the levels detected. Doses to the public In 2014, the total dose from all pathways and sources of radiation was less than 0.005 mSv (Table 5.1), or less than 5. Defence establishments 153 Liquid waste discharges and aquatic 0.055 mSv (Table 5.1), which was less than 6 per cent of monitoring the dose limit. The representative person was an adult living on a local houseboat. Virtually all of this dose was Discharges of radioactive liquid effluent are made under due to the effects of Sellafield discharges. A similar dose permit to the sewage works at Silchester (Figure 3.4), was found in 2013 (0.076 mSv). The decrease observed and to the Aldermaston stream. Discharges of alpha was due to a decrease in dose rates underlying the and other beta radionuclides to Silchester in 2014 were houseboat. Source specific assessments for a vegetable similar to those reported in 2013; discharges of tritium to consumer and a person living on a local houseboat were Aldermaston Stream were very low and similar to those in also carried out. The doses in 2014 were both less than 6 previous years. There are two factors behind the longer- per cent of the dose limit. As for total dose, the Sellafield term decline in discharges of tritium from Aldermaston source dominated the effects at the houseboat. No (Figure 5.1): the closure and decommissioning of the assessment of seafood consumption was undertaken in original tritium facility (the replacement facility uses 2014 because of the absence of relevant monitoring data. sophisticated abatement technology that results in the However the dose from seafood consumption is less discharge of significantly less tritium into the environment), important than that from external exposure on a and the historical contamination of groundwater. The houseboat (EA, FSA, NIEA, NRW and SEPA, 2014). historical contamination has been reduced in recent years by radioactive decay and dilution by natural Dose rates in intertidal areas near Barrow were slightly processes. Environmental monitoring of the River Thames enhanced above those expected due to natural (Pangbourne and Mapledurham) has continued to assess background (Table 5.3(b)). This enhancement was due to the effect of historical discharges. the far-field effects of historical discharges from Sellafield as evidenced by the results of sediment analysis from the Activity concentrations for freshwater, fish, crayfish and local area (Table 5.3(a)). No effects of discharges from sediment samples, and measurements of dose rates, Barrow were apparent in the concentrations of radioactivity are given in Tables 5.2(a) and (b). The concentrations in vegetables and grass. All such results are reported as of artificial radioactivity detected in the Thames less than values (Table 5.3(a)). catchment were very low and similar to those for 2013. Concentrations of tritium in samples are reported as less than values. Activity concentrations of artificial 5.3 Derby, Derbyshire radionuclides in River Kennet shellfish were at very low levels and similar to those reported in 2013. Analyses of Rolls-Royce Marine radiocaesium and uranium activity levels in River Kennet Power Operations sediments were broadly consistent with previous years. Limited (RRMPOL), a Gross alpha and beta activities in freshwater samples subsidiary of were below the WHO screening levels for drinking water, R. Derwent Nottingham Rolls-Royce plc, and this pathway of exposure has been shown to be carries out design, insignificant (Environment Agency, 2002a). development, Derby testing and Site manufacture of 5.2 Barrow, Cumbria nuclear-powered submarine fuel at its At Barrow, BAE two adjacent sites Site Systems Marine in Derby. Small Limited (BAESM) discharges of liquid effluent are made via the builds, tests and Megaloughton Lane Sewage Treatment Works to the River commissions new Derwent and very low concentrations of alpha activity are nuclear powered present in releases to atmosphere. Other wastes are submarines. disposed of by transfer to other sites, including the LLWR Barrow-in-Furness Discharges may be near Drigg. A revised permit became effective on Barrow made under permit 1st November 2013, reducing the gaseous discharge limit but there were for uranium. The variation has removed a limit for aerial none in 2014. The emissions associated with “legacy” waste from the Nuclear FSA’s terrestrial Fuel Production Plant (NFPP) permit. The limits for “normal monitoring is limited fuel production” are retained and in the varied permit no to vegetable and grass sampling and the Environment distinction will be drawn between “normal” and “legacy” Agency monitors dose rates and analyses sediment samples emissions. There have been no aerial emissions reported from local intertidal areas. The latter is directed primarily at from NFPP under the legacy limit for a number of years. the far-field effects of Sellafield discharges. A habits survey was undertaken in 2012 (Garrod et al., 2013b). The total A habits survey was undertaken at Derby in 2009 (Elliott dose from all pathways and sources of radiation was et al., 2010). 154 5. Defence establishments 0.2 3H 241Pu 0.08 241 Pu GBq y Pu GBq -1 0.1 H TBq y 0.04 -1 3 0 0 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 Figure 5.1. Trends in liquid discharges of tritium and plutonium-241 from Aldermaston, Berkshire 1990-2014 (including discharges to River Thames at Pangbourne, Silchester sewer and Aldermaston Stream) Doses to the public 5.4 Devonport, Devon In 2014, the total dose from all pathways and sources of Devonport consists radiation was less than 0.005 mSv (Table 5.1), which is Tamar Site of two parts: the Estuary less than 0.5 per cent of the dose limit. Source specific Naval Base and assessments for consumption of vegetables, fish and Devonport Royal drinking river water at high-rates, and for a local resident Devonport Dockyard, which are exposed to external and inhalation pathways from gaseous Plymouth owned and discharges, give exposures that were also less than operated by the 0.005 mSv in 2014 (Table 5.1). MoD and by Babcock Results of the routine monitoring programme at Derby International Group are given in Table 5.3(a). Analysis of uranium activity in plc, respectively.