Scientists are still studying the after-effects of the nuclear disaster caused by an atomic bomb dropped on Hiroshima on August 6, 1945. The amount of neutron fluence, for example, has been calculated from the site to establish what might be a safe level of exposure for humans. (Neutron fluence is the number of neutrons from the blast found per square centimeter.) The advent of nuclear accidents such as Three Mile Island and potential nuclear accidents in the future makes accurate information imperative. But scientists have recently realized that there are discrepancies in earlier estimates and have been looking for ways to resolve them. According to the latest research, the standards for a safe level of exposure to humans might be too conservative.
Analyzing the neutron-induced fission tracks on certain objects found in Hiroshima enables scientists to calibrate the nuclear fluence. Geologist Robert L. Fleischer (Union College in New York), S. Fujita (Radiation Effects Research Institute in Japan), and M. Hoshi (Research Institute for Nuclear Medicine and Biology in Japan) have published their findings on a glass button found near ground zero in Hiroshima in the Health Physics Society Journal.
More recently, Union College geology student Jonathan MacDonald joined the team to determine the track density of fission tracks in porcelain fragments that were also found near ground zero. This study complements the previous work.
At face value, these results are fluence values from a specific bomb event that will hopefully never be used again. These fission events occurred when thermal neutrons from the bomb caused fission in the normal trace amounts of uranium in the material, MacDonald explained.
We determined the track density on the exterior glaze (glass), on the outside of one porcelain fragment and in a cross section of the glaze in another.
While the value of the one sample nearly matches the previous estimates, the other one is 2Page: 1 2 Related biology news :1
Contact: Ann Cairns
Geological Society of America
. New research shows plants can shuffle and paste gene pieces to generate genetic diversity2
. Building the whole cell from pieces3
. Scans link 2 key pieces of schizophrenia puzzle4
. UNC-CH scientists create worlds smallest pieces of ice5
. Environmental jigsaw pieces fall into place6
. Picking prostanoids to provide protection7
. Study by Israeli scientists provides insight on DNA code8
. Adaptive changes in the genome may provide insight into the genetics of complex disease9
. Essential smell gene may provide key to new insect repellents10
. Clemson University spin-off uses corn to make plastics, provide cleaner air11
. Method to visualize gene activity may provide insight into normal development & genome function