Estimation of Sb V and Sb III in simulated primary coolant water

Characterization of Sb 5,3 has important applications in a variety of matrices. The primary coolant pump seals employed in the Pressurized Heavy Water Reactors (PHWRs), are made of antimony-impregnated graphite. The pH of primary heat transfer fluid is maintained at pH 10 using lithium oxide which helps prevent/reduce corrosion in primary heat transfer piping which are made of C steel. Due to aggressive conditions like high flow, temperature and radiation field, the Sb present in the pump seals comes in to the system as a result of erosion/corrosion. The inactive Sb goes to the reactor core during coolant circulation and deposits on the in-core zircaloy surfaces. Neutron flux present in the core activates this Sb to radioactive isotopes 122Sb (t1/2 2.6 days) and 124Sb (t1/2 60 days). During the decontamination process using different formulations it has been seen that antimony gets mobilised and is found in the decontamination solution however the Sb nuclides do not get quantitatively picked up on the cation exchange column. It is known that the chemistry of any elemental species depends on the oxidation state and antimony present can be either in the lower oxidation, the higher oxidation state, the reduced metallic state or it could be in a mixed oxidation state depending on the conditions in the PHWR. A sample prepared under simulated reactor conditions i.e. heating antimony metal with lithium hydroxide (pH 10), was investigated to study the oxidation state of antimony present in the leached solution