Radiological protection report 2016

In the radiological protection report 2016, the Swiss Federal Nuclear Safety Inspectorate (ENSI) provides an overview of the radiological protection in its area of supervision. Part A of the report deals with protecting the staff of nuclear power plants from the dangers of ionising radiation. It also includes a list of the personal doses accumulated by the staff, broken down using various parameters. Applying the optimisation imperative, it has been proved possible to significantly reduce the annual collective doses in Switzerland's nuclear power plants since they came on stream thanks to major efforts by the operators. In 2016, a total of 6,153 people measured accumulated 2,877 person-mSv. The collective doses have reached a low level corresponding to the radiological condition of the plants and the scope of the work required to be performed in controlled zones (e.g. non-destructive materials testing). ENSI will continue to follow the trend for collective doses and assess the reasons for local variances as well as for measures initiated. The individual doses for people employed in ENSI's area of supervision in 2016 showed a maximum figure of 10 mSv and a mean value of 0.5 mSv which was significantly below the dose limit of 20 mSv for occupational radiation exposure. The discharge of radioactive substances with the exhaust air and waste water from nuclear power plants are dealt with in Part B of the report. In 2016, nuclear power plant operators again met the admissible release limits set by the authorities, in some cases by a considerable margin. The emissions of Swiss nuclear power plants led to a dose of less than 0.01 mSv per year in the direct neighbourhood. A comparison with the average annual radiation dose for the Swiss population of 5.5 mSv shows that the relevant contribution from nuclear power plants lies in the area of one percent of this figure. Effluents from Swiss nuclear power plants were also below the target of 1 GBq per year set by ENSI on the basis of international recommendations. ENSI uses inspections and comparative measurements to ensure that the necessary calibrated radiological protection measurement equipment is available and that it is used for its intended purpose in order to determine correct values. For this purpose, it operates a test centre accredited to ISO 17025. The network operated by ENSI for automatically monitoring the dose rate in the vicinity of nuclear power plants measures dose rates in the vicinity of nuclear power stations all year round and 24 hours a day. The 10-minute, hourly and daily mean rates measured can be viewed on ENSI's web site in real time. This monitoring network serves to secure evidence for the authorities and in dealings with the public. No local increases in dose rates that could be attributed to discharges from nuclear power plants were detected in the reporting year. Sporadic, locally high measurements are due to fluctuations in natural background radiation, e.g. after rainfall. The programme JRODOS (Java-based Realtime Online DecisiOn Support system) has been used since the beginning of 2016 to model atmospheric spread and calculate the dose, should an event occur. JRODOS allows the direct use of 3D weather forecast data from the COSMO-1 model routinely used by MeteoSwiss with a grid size of 1 km. The COSMO-1 model supplies forecasts stretching up to 24 hours into the future with high spatial and temporal resolution. In order to reflect the small scale structure of the Swiss countryside and that of southern Germany, JRODOS uses the very high resolution elevation model from the Swiss Federal Office of Topography. This means that together with the aerial radiometric equipment, there are invaluable, precise instruments available at all times for making current assessments (diagnoses) as well as forecasts of the radiological situation. In the reporting year, all thresholds contained in the Federal Ordinance on radiation protection were met. There were no events in the nuclear facilities leading to inadmissible exposure of staff or the population to radiation. ENSI concludes that Swiss nuclear facilities continue to provide good radiological protection in which the optimisation principle is systematically applied