Radioactive gas monitoring device

A radioactive gas monitoring device comprising:

• a sample chamber into which a sampled gas is introduced;
• a plastic scintillation detector detecting radiation emitted from the sampled gas introduced into the sample chamber to output first detection signal pulses;
• an inorganic crystal scintillation detector detecting radiation emitted from the sampled gas introduced into the sample chamber to output second detection signal pulses;
• a first measurement unit calculating a first count rate from the first detection signal pulses to output the count rate, and issuing a first alert when the first count rate becomes higher than a first preset level and issuing a second alert when the first count rate becomes higher than a second preset level higher than the first preset level;
• and
• a second measurement unit calculating a second count rate from the second detection signal pulses to output the count rate, and issuing a third alert when the second count rate becomes higher than a third preset level.