Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Magnesium potassium phosphate cements to immobilize radioactive concrete wastes generated by decommissioning of nuclear power plants

  • Pyo, Jae-Young (Division of Advanced Nuclear Engineering, Pohang University of Science and Technology (POSTECH)) ;
  • Um, Wooyong (Division of Advanced Nuclear Engineering, Pohang University of Science and Technology (POSTECH)) ;
  • Heo, Jong (Division of Advanced Nuclear Engineering, Pohang University of Science and Technology (POSTECH))
  • Received : 2020.09.06
  • Accepted : 2021.01.05
  • Published : 2021.07.25
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Abstract

This paper evaluates the efficacy of magnesium potassium phosphate cements (MKPCs) as waste forms for the solidification of radioactive concrete powder wastes produced by the decommissioning of nuclear power plants. MKPC specimens that contained up to 50 wt% of simulated concrete powder wastes (SCPWs) were evaluated. We measured the porosity and compressive strength of the MKPC specimens, observing them using scanning electron microscopy and X-ray diffraction. The addition of SCPWs reduced the porosity and increased the compressive strength of the MKPC specimens. Struvite-K crystals were well-synthesized, and no additional crystal phase was formed. After thermal cycling and after immersion, MKPC specimens with 50 wt% SCPWs satisfied the waste-acceptance criteria (WAC) for compressive strength. Semi-dynamic leaching tests were performed using the ANS 16.1 method; the leachability indices of Cs, Co, and Sr were 11.45, 17.63, and 15.66, respectively, which also satisfy the WAC. Thus, MKPCs can provide stable matrices to immobilize radioactive concrete wastes generated by the decommissioning of nuclear power plants.

Keywords

Acknowledgement

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (Ministry of Science and ICT) (No. 2017M2B2B1072405).

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