RRFM 2009 Transactions - European Nuclear Society

1x10 5 0
Specific activity [Bq/liter]
8x10 4
6x10 4
4x10 4
2x10 4
Operation in 2007-2008
: Cs-138
: Tc-101
: Ba-139
: Xe-135
: PCS
1500
1200
900
600
300
PCS radiation [cps]
0
1-1 5-1 9-1 1-1 5-1 9-1
Date [m-d]
Fig 3. Variations of the delayed neutron measurements of the PCS radiation monitor and the
activity concentrations of selected nuclides.
In the real operation period of HANARO, a very small fuel defect which resulted in a much
smaller signal than that required to trigger the fuel failure detection system (FFDS) could be
detected by this method. So far, the gamma-ray spectroscopy for the reactor coolant takes lots
of time, and the procedure is fairly complicated. Thus, it is very hard to apply this method to the
reactor protection system. However, this method would be very useful as an auxiliary measure
for the analysis of a small defect on the fuel.
5. Conclusion
The radionuclides in the primary coolant of HANARO were investigated by gamma-ray
spectroscopy, and this analysis was applied to the detection of the fuel defect. The proper
nuclides and gamma-ray peaks for the object were determined. During the real operation
period of HANARO, a very small fuel defect which resulted in a much smaller signal than that
required to trigger the fuel failure detection system could be confirmed. Therefore, it is
confirmed that this method is very useful as one of the auxiliary measures for the fuel defect
detection in research reactors.
6. References
1. S. K. Ayazuddin, T. Hayat, A. A. Qureshi and H. A. Khan, “Fuel-failure detection system for
Pakistan Research Reactor-1” Ann. Nucl. Energy, 24 (1997) 1213.
2. Myong-Seop Kim, Byung-Chul Lee, Sang-Jun Park and Byung-Jin Jun, “Sensitivity of fuel
failure detection by the delayed neutron measurement in the primary cooling circuit of
HANARO, Ann. Nucl. Energy, 33 (2006) 1134.
3. K. Debertin and R. G. Helmer, Gamma- and X-ray spectrometry with semiconductor
detectors, North-Holland, 1988.
4. G. F. Knoll, Radiation Detection and Measurement, John Wiley & Sons, 2000.
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