Affiliation:
1. Tehran University of Medical Sciences, Tehran, Iran
2. Atomic Energy Organization of Iran, Environmental Engineering Laboratory, Tehran, Iran
3. Iran University of Medical Sciences, Tehran, Iran
Abstract
The objectives of this research were to determine the levels of radioactivity
in the Tehran research reactor containment and to investigate the mass-size
distribution, composition, and concentration of radionuclides during
operation of the reactor. A cascade impactor sampler was used to determine
the size-activity distributions of radioactive aerosols in each of the
sampling stations. Levels of a and b activities were determined based on a
counting method using a liquid scintillation counter and smear tests. The
total average mass fractions of fine particles (particle diameter dp < 1 mm)
in all of the sampling stations were approximately 26.75 %, with the mean and
standard deviation of 52.15 ? 19.75 mg/m3. The total average mass fractions
of coarse particles were approximately 73.2%, with the mean and standard
deviation of 71.34 ? 24.57 mg/m3. In addition to natural radionuclides,
artificial radionuclides, such as 24Na, 91Sr, 131I, 133I, 103Ru, 82Br, and
140La, may be released into the reactor containment structure. Maximum
activity was associated with accumulation-mode particles with diameters less
than 400 nm. The results obtained from liquid scintillation counting
suggested that the mean specific activity of alpha particles in fine and
coarse-modes were 89.7 % and 10.26 %, respectively. The mean specific
activity of beta particles in fine and coarse-modes were 81.15 % and 18.51 %,
respectively. A large fraction of the radionuclides' mass concentration in
the Tehran research reactor containment was associated with coarse-mode
particles, in addition, a large fraction of the activity in the aerosol
particles was associated with accumulation-mode particles.
Publisher
National Library of Serbia
Subject
Safety, Risk, Reliability and Quality,Nuclear Energy and Engineering