DETERMINATION OF 16N GAMMA RADIATION FIELDS AT BWR NUCLEAR POWER STATIONS

摘要

Measurements of environmental gamma radiation fields produced by 16N in components above the floor in the turbine buildings of two large BWR power plants were carried out in April 1975, using pressurized argon ionization chambers and NaI(Tl) and Ge(Li) spectrometers. Both turbine buildings are heavily side-shielded., so that the bulk of the radiation outside the buildings is skyshine. The shapes and amplitudes of the profiles of absorbed dose in air vs. distance are dependent on details of the source (s) shielding - detector geometry. Doses of the order of 10 mrad y-1 were observed at 500 meters.nEnvironmental 16N dose rates as a function of reactor power were continuously monitored with an ionization chamber. A model of 16N source variations that relates steam line transport times and radioactive decay rate adequately describes these data.nIn-plant comparisons of readings of TLDs and portable survey instrumentation in the high 16N photon fields within the turbine building indicated that routine health physics measurements of such fields are probably accurate to about ±30 percent (s.d.).nGeneral methodologies for measurements of 16N photon fields are discussed in the Appendix.