Annual report on radioactive discharges from Winfrith and monitoring the environment 1989

The numerical values of the authorised limits are based on past performance, future requirements and the application of BPM. As a 'back-stop', 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 of the International Commission on Radiological Protection (ICRP) for dose to a member of the general public is 1.0 mSv per year. During 1989 some small changes took place in our discharge patterns, our environmental monitoring and in the assessment of critical group doses. These changes are discussed in the introductions to the two parts of this report where the relevant Authorisations are also discussed. This report, the fifth of our annual series, has as its aim the provision, to the general public, of full information on discharges from the SGHWR reactor and other smaller sources at Winfrith and the associated environmental monitoring programmes. Some improvements in presentation have been made. The data, mainly provided graphically in the main text, are still compared with authorised limits or derived levels, but numerical values are now given. The graphs refer to specifically authorised radio-nuclides e.g. tritium, rather than to gross activity. Previous reports were restricted to monitoring at the site boundary and to off-site monitoring. Some data are now given in the report for on-site monitoring. (author)