Annual report on radioactive discharges from Winfrith and monitoring the environment 1994

This annual report, the tenth of its type, aims to provide full information on our discharges and environmental monitoring. The report is mainly graphical, comparing past and current levels with authorised limits, derived limits or the recommended limits of the International Commission on Radiological Protection (ICRP). All the data are presented at the end of the report in tabular form. All graphs now start at 1972, earlier data may be found in previous reports. Discharges from Winfrith are subject to Authorisations issued jointly by Her Majesty's Inspectorate of Pollution (HMIP) and the Ministry of Agriculture, Fisheries and Food (MAFF). These Authorisations, one for discharges to the sea and one for discharges to the atmosphere, require that Winfrith establish a need to discharge; that we apply Best Practicable Means (BPM) to reduce our discharges; that our discharges shall not exceed set Authorised Limits; and that schedules of Environmental Monitoring are established. We are subject to regular inspection and we are required to undertake monitoring programmes stipulated by the Authorising bodies. Full records are maintained and sent to them. The numerical values of the Authorised Limits are based on past performance, future requirements and the application of BPM. Discharges at the limits must not result in doses to the most potentially exposed part of the local population - the Critical Group -exceeding 0.5 mSv per year. The limit recommended by the International Commission on Radiological Protection (ICRP) for dose to a member of the general public is 1.0 mSv per year. In September 1990 operations of Winfrith's Steam Generating Heavy Water Reactor (SGHWR) ceased. The pattern of discharges and Critical Group doses therefore changes from that date. (UK)