Correspondence and difference between gamma-ray and neutron irradiation effects on organic materials in marine environment

Abstract

This work is devoted to understand the difference between gamma ray effects and neutron influence on organic materials in order to interpret the change occurred in organic matter that coexists with nuclear tests in deep marine environment. A combination of Fourier-transform infrared spectroscopy (FTIR) and a simple statistical analysis was applied as a tool for the quantitative determination of changes in chemical properties due to radiation effects. The primary goal of this work was to statistically deduce, from correlations obtained between different band intensities, more information on the changes occurred. It did not aim only to investigate in detail the PolyAllyl Diglycol Carbonate (PADC) structure due to gamma and neutron irradiation impacts. The PADC samples obtained from Track Analysis System Ltd., UK of TASTRAK type were irradiated with gamma-ray dose in the range from (5±1)×10 3 Gy to (3.0±0.6)×10 6 Gy using 60 Co standard gamma cell of calibrated dose rate. While a high neutron fluence from ETRR-2 research reactor was applied for neutron irradiation process. The results showed a shift in absorption intensities for various bands due to either gamma or neutron irradiation. Such bands are the C=O, C=C and CO -C. Moreover, formation of-OH radical was observed which indicating water content in the studied samples after irradiation. Such induced alterations were due to bond breakage of weak bonds such as, C-H, CO , and CC with different possibilities for gamma irradiation effects. While for neutron irradiation, atomic displacement in the material was the main reason for such changes. Furthermore, by applying a simple statistical analysis test, major infrared bands were integrated in order to make sense of, and draw correlations between each other to get more accurate and comparable results. The obtained results showed a good correlation between some bands, while the other didn't. Also, the applied correlations simplified the comparison between gamma ray and neutron induced effects.