UNSCEAR studies radiation exposure from electricity

Public exposure to radiation resulting from the generation of electricity by nuclear power plants is just a fraction of that from coal-powered plants, according to a report from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).

"The world's mix of electricity-generating technologies changes over time in response to the landscape of climatic, environmental, resource, political and economic challenges. Governments and researchers may conduct various comparative studies that take into account, among other things, the impact of different technologies on the public, on workers and on the environment," UNSCEAR said. "Exposure to ionizing radiation is only one of the many factors that may be taken into account as part of such assessment."

The previous such study was published by UNSCEAR in 1993. The committee said it had updated its methodology for estimating public exposures due to radioactive discharges. It says the new methodology is "more flexible to be able to address a wide range of electricity-generating technologies." The committee has also re-evaluated occupational exposures arising from different generating technologies, using data mainly from dosimetry records of worker exposures.

UNSCEAR yesterday released the results of a comparative study it has conducted of exposures from generating technologies based on nuclear power, coal, natural gas, oil, biofuels, geothermal, wind and solar.

The committee said that while exposure levels are very low, the coal cycle contributed more than half of the total radiation dose to the global population from electricity generation. The nuclear fuel cycle, it said, contributed less than one-fifth of this. The collective dose for coal generating technologies is 670-1400 man Sieverts, depending on the age of the power plant, while that of nuclear is 130 man Sv. This is followed by geothermal at 5-160 man SV, natural gas at 55 man Sv and oil at 0.03 man Sv.

UNSCEAR also evaluated radiation exposure per unit of electricity generated, using 2010 as a reference year for comparison. The committee concluded that the values for coal and nuclear are about the same in the short term: 0.7-1.4 man Sv per GWe for coal and 0.43 man Sv/GWe for nuclear.

It noted over a period of hundreds of years, "an accumulation of very small doses from long-lived radionuclides result in larger collective doses from the nuclear fuel cycle". However, the total collective dose (to both the public and workers) per unit of electricity generated by the coal cycle was larger than that generated by the nuclear fuel cycle, "even when considering the long-lived globally-circulating radionuclides integrated out to 500 years".

The report notes that it is difficult to compare directly exposure from serious nuclear accidents - such as those at Chernobyl and Fukushima Daiichi - to those resulting from routine discharges. UNSCEAR said the collective dose to the global population resulting from serious nuclear accidents was "many orders of magnitude higher" than the collective doses from one year's normal operation of all the technologies assessed. "More significantly," it said, "the distribution of doses after an accident is more localised geographically."

UNSCEAR chair Hans Vanmarcke said, "These results should been seen from the perspective of the share of each technology in worldwide electricity production; 40% of the world's energy was produced by the coal cycle in 2010, which is the baseline year for the assessment, compared with 13% by nuclear." He added, "Of the remaining technologies, the combustion of natural gas and geothermal were important contributors to global public exposure."

He added, "Exposure to radiation and its effects on people have always been of interest to the general public and scientists alike. We can now make more sound assessments of different electricity-generating technologies, as more complete data have been collected and consistent methods for evaluating the different technologies are available."

UNSCEAR said its findings "cannot alone indicate that any one technology is preferable to another". It said countries choose an appropriate energy mix based on a number of factors, which may include radiation exposure.

Researched and written
by World Nuclear News