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

Table 5

Calculation of the detection efficiency of the online monitoring system in the characteristic spectrum interval of Kr-88 (785–885 keV).

Nuclides	Average pulses emitted by the detector in the characteristic spectrum interval of Kr-88  (785–885 keV); (count/particle)	Total γ branch ratio I (number of emitted photons per decay)	Detection efficiency []	Specific activity in the coolant at the exit of the HPS (99.9% purification efficiency); ( Bq·L^–1)
Kr-85m	0.00E + 00	0.892670	0.00E + 00	60.00	0.00E + 00
Kr-87	7.00E – 06	0.779675	4.22E – 06	67.00	2.83E – 04
Kr-88	1.28E – 05	1.239245	1.23E – 05	140.00	1.72E – 03
Kr-89	7.20E – 06	1.272980	7.09E – 06	20.00	1.42E – 04
Xe-133	0.00E + 00	0.000712	0.00E + 00	850.00	0.00E + 00
Xe-133m	0.00E + 00	0.103000	0.00E + 00	28.00	0.00E + 00
Xe-135	0.00E + 00	0.927948	0.00E + 00	130.00	0.00E + 00
Xe-135m	0.00E + 00	0.809970	0.00E + 00	14.00	0.00E + 00
Xe-137	2.00E – 07	0.320150	4.96E – 08	42.00	2.08E – 06
Xe-138	2.60E – 06	1.133639	2.28E – 06	93.00	2.12E – 04
I-131	0.00E + 00	0.962891	0.00E + 00	0.18	0.00E + 00
I-132	3.00E – 06	2.870846	6.67E – 06	2.30	1.53E – 05
I-133	5.80E – 06	0.991557	4.45E – 06	0.92	4.10E – 06
I-134	3.16E – 05	2.885958	7.06E – 05	4.70	3.32E – 04
I-135	1.52E – 05	1.214136	1.43E – 05	1.40	2.00E – 05
Rb-88	7.00E – 06	0.373961	2.03E – 06	7.70	1.56E – 05
Cs-138	0.00E + 00	1.872362	0.00E + 00	1.60	0.00E + 00
	1.88E – 06