Post-Closure Safety Case for the Dounreay Shaft

The ILW Shaft at Dounreay contains around 850 m3 of intermediate level radioactive waste, consigned in the 1960s and early 1970s.


The historic facility does not meet modern safety standards, therefore UKAEA intends retrieving the waste for more suitable management so the Shaft can be safely closed. This requires the facility to be isolated from surrounding groundwater. UKAEA proposes to do this by sealing the rock around the 65 m deep Shaft with cement-based grout, a major engineering project.

Before commencing rock grouting, UKAEA has been required by regulators to assess the long-term safety of the proposed approach. UKAEA contracted Quintessa to develop a detailed Post-Closure Safety Case (PCSC) for the remediated Shaft, and undertake a range of supporting studies. This included a detailed re-evaluation of geology, hydrogeology and geochemistry; an assessment of Shaft closure options; a review of the inventory and a safety assessment. In addition, summary and overview documents were produced. The suite of seven documents comprising more than 800 pages has been successfully submitted to regulators. UKAEA is now beginning rock grouting trials. The PCSC will be periodically updated to benefit from information gained from UKAEA's ongoing research of the Shaft environment.

Image Courtesy of Dounreay Restoration Site Ltd.