Measurement of low energy beta emitters in nuclear facility off-gas
This dissertation is an account of the development of monitoring methods for the semivolatiles /sup 99/Tc and /sup 79/Se, and for the gaseous radionuclides /sup 3/H and /sup 129/I. A continuous technetium-99 monitor was developed. The collected technetium-99 was counted by a ruggedized surface barrier detector. The detection limit of 1 x 10/sup -10/ ..mu..Ci/cm/sup 2/ for the integrated system for technetium-99 was sufficient for radiological protection. The selenium-79 continuous monitor was based on distillation from 20% HBr. The counting efficiency of the surface barrier detector was insufficient for the lower energy selenium-79 beta. A time-integrated sampling method that quantitatively collected gaseous technetium-99 and selenium-79 was developed. The procedure developed for chemical separation was compatible with liquid scintillation counting, was free of interferences commonly found in the off-gas of waste solidification facilities, and detected selenium-79 and technetium-99 at the 10/sup -10/-10/sup -11/ ..mu..Ci/cm/sup 3/ level in the Idaho Chemical Processing Plant (ICPP) stack. A continuous tritium monitor was developed that used a permeation distillation dryer to separate the tritium from /sup 14/C and /sup 85/Kr. The separated tritium was then measured by an on-line 20-L ionization chamber. An in-plant demonstration proved the monitor's response characteristics, i.e., accuracy, and sensitivity, were sufficient to detect process transients and to determine routine releases, within the range of 1 x 10/sup -9/ to 1 x 10/sup -4/ ..mu..Ci/cm/sup 3/.
- Research Organization:
- Idaho Univ., Moscow (USA)
- OSTI ID:
- 6928742
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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