RADIATION MONITORING AND ITS METHODS (OPTIONS) Russian patent published in 1998 - IPC

FIELD: nuclear engineering; mechanical engineering, medicine, and other industries where radioactive materials are used. SUBSTANCE: integral number of γ-quantums is measured in equal preset time intervals and measurement data are used to determine threshold level; integral number of γ-quantums recorded during last time interval is compared with threshold level. Novelty is that two threshold levels, upper and lower ones, are determined. Integral number of γ-quantums recorded during last interval, when it exceeds upper threshold level, points to presence of radionuclides. Their absence is recognized by the number of γ-quantums below the lower threshold level. If mentioned number of γ-quantums is between upper and lower threshold levels, this value is additionally recorded during time interval next to last one. Further on, according to first option, number of γ-quantums recorded during additional measurements is compared with lower threshold level and if result obtained is higher than lower threshold level, it indicates that radionuclides are present. According to second option, half-sum of two last records is compared with lower threshold level and radionuclides are recognized by mentioned value exceeding lower threshold level. Radiation monitor has series-connected detector 1, amplifier 2, lower-level discriminator 3, processing unit 4, and alarm indicator 16. Novelty is that processing unit is provided, in addition, with clock generator 6, reading register 7, second comparison circuit 11, AND gates 12, 14, OR gate 15, and D flip-flop 13. EFFECT: reduced probability of false alarm at practically constant probability of radionuclide missing or reduced probability of radionuclide missing at practically constant probability of false alarm. 7 cl, 1 dwg