Magnesium-Potassium Phosphate Matrix for Immobilization of 14C

Abstract

Possibility of using a low-temperature magnesium-potassium phosphate matrix to solve the problem of immobilizing the radioactive wastes containing radioactive carbon (¹⁴C) in the form of calcium carbonate was examined. The physicochemical characteristics of the compounds obtained were determined. Large values of the ultimate compression strength (22 ± 5 MPa), which satisfy the technical requirements for cemented radioactive wastes (no less than 4.9 MPa), were obtained. The minimum carryover of carbon dioxide into the atmosphere in the course of synthesis and in keeping of samples for 14 days was noted: not more than 3 wt % relative to the starting CaCO₃. The leaching rate of carbonate ions from magnesium-potassium compounds by 28th day of contact with air does not exceed 10‒9 g cm^‒2 day^‒1, with this value for the rest of the compound components not exceeding 10^‒4 g cm^‒2 day^‒1. Thus, it was found that the magnesium‒potassium phosphate matrix is an alternative to the cementation for solidification of radioactive wastes containing ¹⁴C.