Decommissioning of nuclear sites

The nuclear industry is working to develop safe and effective strategies for decommissioning nuclear sites and handling decommissioning wastes.

Kemakta has contributed to these strategies with a focus on the assessment of radiological exposure during the demolition of facilities, disposal of waste and, in the long term, from possible scenarios at the disposal site. We have assessed generic exposure situations to define guidelines for waste classification as well as site specific exposures. Our reference projects include:

  • Demolition of an uranium extraction facility at Ranstad
  • Exemption application to landfill waste from Westinghouse
  • Application to extend SKB’s low and intermediate level waste repository (SFR) in Forsmark for the disposal of decommissioning waste. This has included:
    • Post-closure safety
    • Reviewing the waste inventory
  • Characterising long-lived low and intermediate level decommissioning waste for disposal in SKB’s planned repository for this type of waste (SFL)
  • Developing a model (SOIL2U) to assess doses from exposure to soil contaminated by radionuclides, for use in land clearance
  • Defining clearance and exemption levels for:
    • Recycling of scrap metal
    • Material from the demolition of buildings
    • NORM

DOS2U, Kemakta’s dose model for landfill sites

We have developed the dose model DOS2U to support the analysis of alternative disposal options for low-level waste. Input data describes key characteristics of the waste and landfill site, as well as details of how the waste is handled. DOS2U calculates the doses received by workers who handle the waste and members of the public who may be exposed in the future. The calculations take account of radioactive decay and ingrowth, leaching of radionuclides from the waste and the dispersion via groundwater to different recipients. The doses calculated reflect a number of different exposure pathways. DOS2U also calculates the doses received by workers and the public following a possible intrusion into the landfill site. DOS2U has been used to support projects carried out for Ranstad Industricentrum AB and Westinghouse.

Dose2

DOS2U conceptual model

 

SKB’s Clearance Handbook

Kemakta has contributed a chapter on the derivation of conditional clearance levels to SKB’s clearance handbook. This handbook offers guidance to licensees and acts as a key reference in the production of documentation involved in decommissioning and clearance.

For more information contact Mark Elert.

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