RSRL Integrated Waste Strategy - Issue 5- Oct 2012.pdf

NOT PROTECTIVELY MARKED6.2.2 Radioactive Gaseous Discharges256. Harwell was authorised under the Radioactive Substances Act 1993 (RSA) for thedischarging of waste gases, mists and dusts to atmosphere; on 6 April 2010, thisauthorisation automatically became an environmental permit under EPR2010. Gaseouswastes are sampled at the point of discharge and the results analysed and reported on afour weekly basis to EA. The site keeps discharges to a minimum through the use of BPMand there has been a decrease in the activity discharged each year. Sources of radioactivegaseous discharges include:• tritium from the Material Testing Reactors (MTRs)• tritium, radon, alpha and beta from the Solid Waste Complex• radon, alpha and beta from the Radiochemical Building257. Gaseous wastes are controlled by ventilated containment incorporating HEPA (HighEfficiency Particulate in Air) filters which remove particulates and are subsequently disposedof as LLW. There is no abatement of tritium, krypton or radon before discharge toatmosphere, as this is not practicable. No change is planned to the treatment of radioactivegaseous discharges prior to achieving the site end state and there will be no futuredischarges once the site end state is achieved.258. Radioactive gaseous discharges were covered in the BPEO review of wastes on theHarwell site carried out for EA in 2006. They were also included in the site waste BPEOstudy during which the current strategy of physical separation/filtration was identified as thesole practicable option. Radioactive gaseous discharges are controlled on a facility byfacility basis and there are authorised limits for each building. Thus there are nodependencies between facilities although there is a total site discharge limit for each nuclideor group of nuclides.259. Key stakeholders include EA, ONR, local residents and critical groups for radiationexposure. EA is consulted on environmental issues and ONR is consulted on safety issueswith respect to the discharges of radioactive gases. An annual report is made to the LocalStakeholder Group and includes data on past discharges and future predicted discharges.260. There is an assumption that the discharge permits will be sufficient to meet operationalrequirements during decommissioning and that best practicable means will be applied tominimise the levels of radioactivity discharged. Constraints relating to radioactive gaseousdischarges impact mainly on the treatment of tritium sources in the Solid Waste Complex.Historic records indicate that the current strategy of releasing tritium to the atmospherecould cause annual discharge limits to be exceeded. Work is in progress to revisit theinventory and to determine if the permitted limit needs increasing.261. For the MTRs an assessment of the discharges during decommissioning will be needed.There is a risk that the tritium levels may exceed authorised limits.262. Research and technology developments include the assessment of radioactivedischarges to atmosphere during the decommissioning of the MTRs. This will be carried outduring the front end engineering phase. Interfaces with other waste streams include tritiumsources in the ILW stream from which the tritium needs to be released before packagingand conditioning into 500-litre drums. The HEPA filters used to filter particulates from air aredisposed of as LLW.263. Plans to achieve the commitments and milestones contained within the NationalRadioactive Discharge Strategy involve the minimisation of discharges through applicationof best practicable means. At times it may be BPEO to increase the radioactive dischargesRSRL IWS (Issue 5 – October 2012)75