Postclosure safety assessment support to Canadian Nuclear Laboratories

Working alongside Arcadis Canada, Quintessa is supporting Canadian Nuclear Laboratories (CNL) in preparation of postclosure safety assessments for two key decommissioning projects: the in-situ disposal of the Nuclear Power Demonstration (NPD) facility; and the proposed Near Surface Disposal Facility (NSDF) on CNL’s Chalk River site in Ontario.

Both assessments are being undertaken using an iterative approach and are being carried out using international best practice in the form of the International Atomic Energy Agency’s (IAEA’s) Improving Safety Assessment Methodologies (ISAM) guidance. The calculations have been undertaken using Quintessa’s AMBER compartment modelling software. Results from the work have been presented at two conferences during 2019:

Nava Garisto from Arcadis attended WM2019 in March 2019, giving oral presentations on the assessment work that has been carried out for both sites. In particular, the joint Arcadis-CNL-Quintessa paper on “Postclosure Safety Assessment for the Nuclear Power Demonstration Closure Project” has been awarded the accolades of ‘Superior Paper’ and a 'WM2019 Paper of Note'. The abstract for this paper is below.

Following 30 years in a safe shutdown state, Canadian Nuclear Laboratories (CNL) is proposing the final decommissioning of the Nuclear Power Demonstration Waste Facility (NPDWF). A Postclosure Safety Assessment (PostSA) has been prepared as part of this process. The present PostSA represents the second assessment, following an iterative approach. The PostSA considered Normal Evolution of the facility, as well as several Disruptive Events and other cases to show robustness and account for uncertainties. The results of the PostSA show that the NPDWF is a robust design that will contain and limit release of contaminants long into the future.

Quintessa's Kate Thatcher and James Penfold, together with collaborators from Arcadis, attended NWMDER in September 2019. Quintessa employees are co-authors on the following two papers: “Select Sensitivity Cases for the NSDF Waste Facility” and “Nuclear Power Demonstration Closure Project Postclosure Safety Assessment: Radiological and Chemical Aspects”.

Lead Image: Photo provided courtesy of K. Thatcher.