Fig. 1. Variations of collective doses of Ignalina NPP and outside workers in 1999 to 2009 normalized to one unit
The annual collective dose of Ignalina NPP workers was 963.9 man mSv, of outside workers – 69.5 man mSv. It should be noted that in 2009 the total collective dose of Ignalina NPP and outside workers was approximately 3 times lower than in 2008.
The decrease trend of Ignalina NPP outside workers collective doses is being monitored since 1998. The key reason having determined such occupational exposure change was the reduced scope of works of the planned outage of the 2nd unit due to the planned unit decommissioning at the end of 2009. Therefore the collective dose received during outage reached as low as 25% of the total annual collective worker dose, though in the previous year this indicator reached approximately 60-70%. These changes are best reflected in exposure of outside workers which reduced approximately 15 times compared to 2008.
The risk of internal exposure (radionuclide activity in the body) of workers is increasing during maintenance works. Therefore internal exposures are annually monitored. In 2009 the dose exceeding the minimum detectable activity was reported by Ignalina NPP for 188 workers out of 1910 monitored ones. The highest internal exposure dose (0.28 mSv) was reported for a worker of Ignalina NPP Reactor Department representing 1.4% of permissible annual dose limit. The results of internal exposure monitoring of Ignalina NPP and outside workers are presented in Fig. 2.
