Investigating the possibility of using phenol-formaldehyde polymer as a nuclear gamma ray shield

Resol polymer (as a type of phenol-formaldehyde polymer) was synthesized from phenol and formalin of 40% concentration by a melt-condensation technique. Resol polymers were characterized by IR spectroscopy and elemental analysis of C and H. The possibility of using such a polymer as nuclear gamma ray shield was investigated. Three different forms of the polymer (polymer without additive, polymer with 5% by weight of Pb and polymer with 25% by weight of Pb) were used as a single shield. The attenuation coefficient (μ) and buildup factor (B) were measured and analyzed for all three forms. Different gamma ray energies were chosen by using two gamma ray sources; namely 60Co and 137Cs, where 60Co has a half life time of 5.2714 years, with a activity level of 0.00837 mCi = 3.0954 x 105 Bq and two energy peaks of 1.332 MeV and 1.173 MeV, whereas 137Cs has a half life time of 30.04 years, an activity level of 0.0880 mCi = 3.2 x 106 Bq and an energy peak of 0.66 MeV. The additives have observable effects on the investigated parameters. In particular, it is found that by increasing the Pb additive to the polymer the attenuation coefficient (μ) increases also, and at the same time the buildup factor (B) decreases. It was also found that the hardness of the polymer increases with time of exposure to radiation. (authors)