Assessment of environmental radiation monitoring data inHungary following the Fukushima accident

Abstract

The unusually strong earthquake in Japan on 11 March 2011 and the following extremetsunami caused enormous damage in the buildings of Fukushima Dai-ichi Nuclear Power Plant(NPP) situated on the Pacific coastline of Japan. The accident led to the release of alarge amount of radioactive material into the environment. According to the measurementsof the Radiological Monitoring and Data Acquisitions Network (RAMDAN) the radioactiveplume reached Hungary on 24 March 2011. The main volatile fission products –¹³¹I, ¹³⁴Cs, and ¹³⁷Cs radioisotopes – were measurable in aerosoland fallout samples in Hungary. Their activity concentration in air reached the maximumvalue in the last days of March and returned to the background level in the first half ofMay. As a consequence of respiration of contaminated air, a maximum of 1 Bq per capita of¹³¹I could be accumulated in the thyroid gland of the Hungarian population during thegiven period. The calculated upper limits of the committed effective dose from inhalationof ¹³¹I were 4 nSv and 10 nSv to the Hungarian adults and infants,respectively. These values are a hundred thousand times less than the annual radiationdose from natural sources to the Hungarian population. The radiation dose from radioactivecaesium isotopes originating from Fukushima was even less, around 1 nSv on average, toHungarian residents. No health deterioration can be expected from this radiationburden.