Technical note: Effect of the Chernobyl accident on the gamma radiation level in the Belgrade region

Abstract

This article presents the results of measurements of the gamma radiation level during and after the Chernobyl accident at the reference point located near Belgrade, Yugoslavia. The measurements started a day before the arrival of the plume of contaminated air from Chernobyl, were carried out during the active phase of the accident, and continued afterward up to the present day. Those measurements enabled authorities to (1) register the arrival of the central part of the contaminated plume over Belgrade on May I, 1986, at 10:30 a.m. local time; (2) monitor the passing of the plume; (3) record the beginning of substantial deposition of radioactive materials caused by heavy fallout in the afternoon of the same day; and finally, (4) record the moment the maximum deposition level (i.e., gamma radiation level) was reached the next day. The results of the measurements in postaccident conditions indicated the decrease of the gamma radiation level because of radioactive decay of deposited gamma emitters and the influence of various environmental factors. The measurements were carried out by a high-pressure argon ionization chamber. Presented data may be used for testing of atmospheric dispersion and deposition models and also for predicting the behavior of deposited gamma emitters in the environment over a long time period after a nuclear accident.