Design of the Online Gross γ Monitoring Instrument at the Exit of the Helium Purification System in HTR-PM

Table 4

Calculation of the detection efficiency of the online monitoring system over the entire spectrum (100–3000 keV).

Nuclides	Average pulses emitted by the detector (count/particle )	Total γ branch ratio (number of emitted photons per decay)	Detection efficiency []	Activity concentration in the coolant in the exit of helium purification system (99.9% purification efficiency); (Bq·L^–1)
Kr-85m	2.674E – 04	0.892670	1.848E – 04	60.00	1.11E – 02
Kr-87	4.102E – 04	0.779675	2.476E – 04	67.00	1.66E – 02
Kr-88	4.302E – 04	1.239245	4.127E – 04	140.00	5.78E – 02
Kr-89	4.050E – 04	1.272980	3.991E – 04	20.00	7.98E – 03
Xe-133	2.738E – 04	0.000712	1.509E – 07	850.00	1.28E – 04
Xe-133m	3.194E – 04	0.103000	2.547E – 05	28.00	7.13E – 04
Xe-135	3.312E – 04	0.927948	2.379E – 04	130.00	3.09E – 02
Xe-135m	3.760E – 04	0.809970	2.358E – 04	14.00	3.30E – 03
Xe-137	3.700E – 04	0.320150	9.170E – 05	42.00	3.85E – 03
Xe-138	3.948E – 04	1.133639	3.465E – 04	93.00	3.22E – 02
I-131	3.536E – 04	0.962891	2.636E – 04	0.18	4.74E – 05
I-132	4.040E – 04	2.870846	8.978E – 04	2.30	2.06E – 03
I-133	3.804E – 04	0.991557	2.920E – 04	0.92	2.69E – 04
I-134	4.084E – 04	2.885958	9.124E – 04	4.70	4.29E – 03
I-135	4.344E – 04	1.214136	4.083E – 04	1.40	5.72E – 04
Rb-88	4.488E – 04	0.373961	1.299E – 04	7.70	1.00E – 03
Cs-138	3.616E – 04	1.872362	5.241E – 04	1.60	8.39E – 04
	1.19E – 04