1. Svitek Jaroslav, Bohunice NPP, Slovak Republic
Contamination control at the exit from radiation controlled area and NPP site at Bohunice NPP
Svitek Jaroslav, Bohunice NPP, Slovak Republic

2. Introduction Bohunice NPP-list of reactor units Name Unit Operation V1
PWR, Unit1, VVER-230
1978
PWR, Unit2, VVER-230
1980 V2
PWR, Unit3, VVER-213
1984
PWR, Unit4, VVER-213
1985

3. Contamination monitors at RCA boundary
The first measuring point
Surface contamination of clothes
Old fashioned monitors RZB-04-04, RUSSI-1
The second monitoring point
Perssonel – new monitors APM-3A
Small obhjects – new monitors CPO
May 2001 – new monitors were put in operation

4. RUSSI-01, RZB-04-04 monitors 15 pcs detectors
   Each detector contains 2pcs GM tubes type SBT 10
   1071 cm2 total monitoring area
   Measuring time – 5 seconds
   Alarm level set – 3 Bq/ cm2
   Entry/exit barriers
   Calibration source - 90Sr

5. APM-3A monitor - 1 Two steps monitor
   Alpha, beta and gamma-ray sensitive
   20 pcs LFP-800 detectors for monitoring of
hands, bodies and feet
   2 pcs LFP-330 detectors for monitoring of heads
   4 pcs LFP- 800 detectors for monitoring of small
objects ( items monitor )
   Feet, hands and body photosenzors
   Over 2x16000 cm2 of active monitoring area
for total coverage of the body
   3200 cm2 of active monitoring area in items
monitor

6. APM-3A monitor - 2 Entry/exit barriers Low P-10 gas consumption
Reader for ID-cards
Alarm set point – 45Bq/cm2
Calibration source - 137Cs

7. CPO monitor Two large area scintillation detectors (1225 cm2 each)
Lead shielding (25 mm)
Entry/exit barriers
Audible warning.
Calibration source - 60Co
Alarm level set 90 Bq

8. Activity monitor at NPP site - PM7 monitor
Walk through mode 
Lead shielding
RDA of PM7 monitor - (9.2 – 10.4) kBq
6 pcs plastic scintillation detectors
Calibration source Cs
In operation since January 1998

9. Experience with installation
PM 7
Measuring algorithm of PM7 had been accommodated
APM-3A
Problems with the control of the P10 gas flow
Large number of shoe soles contamination
Corrective actions
More frequent washing of the hot change rooms
Deco foils at the entrance to the hot change rooms

10. No of personnel contamin.
The number of contamination
Year
No of personnel contamin.
No of object contamin.
Other
Radio –
therapy
1998 37 6 5
1999 19 10 3
2000 22 7 2
2001 4
after the modern.

12. Analysis of the events revealed:
Analysis of the events revealed:
 More than 70% events of personnel contamination was
caused by insufficient characteristics of old equipment
RZB and RUSSI-1at the exit from RCA
 Less than 30% of personnel contamination was caused by
human error - by violation of RP rules at the exit from RCA
 Up to 60% of events was caused by the contractors workers
 Up to 80% of all events was found at JE V-1 which was
caused by a large extend of reconstruction works during the
reconstruction and the higher contamination of the primary
circuit
 All contamination events represent only negligible risk
on the human health

13. Conclusion The first event of contamination at the personal site gates
The first event of contamination at the personal site gates
was found after the installation of monitors PM 7
The main cause of the taking out of the contamination
from the RCA was the insufficient monitoring equipment
at the RCA boundary
The problem was eliminated by replacing old monitors
through new ones