The Evaluation of Doses for 2004
In Dukovany NPP in 2004 in total 1,953 employees were monitored using dosimeters (of this number 592 employees were the skeleton personnel of Dukovany NPP and 1,361 supplier employees), the cumulative collective effective dose was 673.79 mSv (including all doses exceeding 0.05 mSv) and an average personal effective dose 0.50 mSv, the highest yearly individual effective dose was 5.37 mSv (detected with an employee of a supplier organization).
In Temelín NPP in 2004 in total 1,758 employees were monitored using dosimeters (of this number 499 employees were the skeleton personnel of Temelín NPP and 1,259 supplier employees), the cumulative collective effective dose was 468.34 mSv (including all doses exceeding 0.05 mSv) and an average personal effective dose 0.35 mSv. The highest yearly individual effective dose was 8.93 mSv (detected with an employee of a supplier organization).
In the uranium-mining industry, a total of 344 employees were monitored at the underground workplaces of GEAM Dolní Rožínka. The cumulative collective effective dose was 3.1 Sv; the average individual effective dose was 8.99 mSv. The highest individual effective dose in 2004 was 27.73 mSv (underground); a total of 550 employees in the uranium-mining industry were monitored with a cumulative collective dose of 3.9 Sv.
With other industrial applications, about 2,300 employees were monitored whose average individual effective dose, depending on their profession, ranged from 1 to 2 mSv; professions with higher doses are crack detection (1.2 mSv) and logging work (4.5mSv).
At medical workplaces with ionizing radiation sources, doses were evaluated for almost 12,000 employees. Of this number, nearly 50% had a yearly individual effective dose below recording level, the remaining employees showed an average yearly individual effective dose of 1.1 mSv; with certain professions the average yearly individual effective dose is higher as usual, e.g. with doctors – cardiologists ranged about 3.5 mSv.
Personnel of specialized professions, such as service and inspections at the sources, personnel of approximately 960, achieved an average yearly individual effective dose of about 0.5 mSv.
The collective effective dose in 2004 was estimated at 13.5 Sv. The average yearly individual effective dose per single monitored employee was estimated at 0.62 mSv.
In 2004 three cases of single-shot exposure of personal dosimeters with doses exceeding 20 mSv were examined (for the relevant inspection period). Two cases of exposure of finger dosimeters with doses exceeding 150 mSv were investigated. Dosimetric services reported four cases when holders reported impersonal exposure of the dosimeters due to improper handling. This concerned in particular the personnel of companies involved in crack detection.
Within the evaluation of yearly doses in 2003 (the Central Registry processes annual data only in the second quarter of the following year) 36 cases were detected in which the values of personal doses exceeded 20 mSv. Of this number 16 cases were personnel in the uranium mining industry, where inspection and control of personal doses is assured continuously and these doses are thus not re-examined. Eighteen cases in the health service field were re-examined; found data were reduced to attenuation with a protective apron. One case of the total number involves the field of crack detection – 23 mSv. In general, crack detection ranks among the activities where personnel exposure is relatively high (an average dose is about 1.5 mSv); all the same, optimization procedures and subsequent technical measures must assure that individual doses of the personnel do not permanently move at the level of stipulated limits. This positive trend occurred in 2002, continued in 2003 and is confirmed by the results from the Central Registry for 2004.
Another group of employees with doses higher than the reported averages are doctors – cardiologists. In October 2004, the SÚJB organized a seminar on the subject of “Radiation protection during intervention examinations”, which was aimed to show the doctors the possibility of optimization when performing their activities and to present international recommendations in this field. Positive response to this action indicated possibilities of further cooperation between the Office and the Expert Medical Corporations.
In relation to personnel exposure management at the workplaces with higher exposure from the natural sources, the inspection activities continued for the second year at the workplaces where the NORM materials or TENORM (Technologically Enhanced Normally Occurring Radioactive Materials) are managed, which are stipulated by the Decree No. 307/2002 Coll. The legislation related to workplaces with increased risk of natural exposure is based on, besides the experiences in natural radioactivity on the territory of the Czech Republic, the studies and recommendations published within the EU. The inspection activities at such workplaces are also used to specify the information on the use of materials with increased content of natural radionuclides, on their origin and method of processing, and on the rate of potential exposure of personnel. The commencement of the inspection activities related to the establishment of entities with permits to perform services of personal dosimetry at determined workplaces.