Submitted by Nhan Tran, Canadian Nuclear Safety Commission Commenting on behalf of the organisation
Our reviewer found that the document is exceptionally well written and include all relevant information and recommendations applicable to near surface disposal facilities.
A few additional comments/suggestions on the draft for consideration:
Line 74/75 & 315/318 paragraph (20): Suggest to add to the goal of a surface disposal facility that protection is provided during the different phases of the development of the disposal facility including post closure (now and in the long term) since the facility waste inventory will certainly contain long-lived radionuclides even with low activity content. This is important and should be specified in the Abstract.
Line 365/366: Disposal by leaving waste in situ , e.g., foundations of decommissioned buildings is not an appropriate example. It is internationally recognized that a foundation of a decommissioned facility/buildings cannot be left in-situ but removed unless justified and approved by the regulatory body. A good example would be a site or an area in which waste was directly buried in trenches a result of past practice activities (legacy waste), yet demonstrated by a safety case and subject to the regulatory review and approval by the regulator body.
Line 402, Figure 3: I suggest adding a legend to this figure showing the different parts and layers (facilities, soil, bedrock, etc.,).
Line 473, Figure 4: It should be recognized that sometimes a decision on “siting (1)” is not required and/or is implicitly included or combined in the decision on “construction (2)”. In addition, the decision on “institutional control (7)” would happen before the start of the post-closure period.
Line 825/826, Table 1 “Recommended Radiological Protection Criteria and Objectives for Near Surface Disposal”. I suggest for context to use/combine Table 1 of this draft with Table 8 of ICRP Publication 103 and Paragraph 2.15 of the IAEA SSR-5 (Disposal of Radioactive Waste) as protection of the public and workers limits should be clearly stated along with dose constraints and reference levels for optimisation particularly during the post-closure period. This information should be explicitly mentioned as it will be considered in the design stage.
Line 825/826, Table 1: I believe that the protective approach description for the pre-operational & operational phase should revisited. During this phase, only regulatory occupational dose limits and radiation protection requirements such as the ALARA principle would apply. Unless I’m missing something here, I am not sure why “dose constraint” is used in this phase since it is applicable to the post-closure phase.
Line 997, minor editorial : “should consider” is stated twice (repeat), usually captured by the editors review.
Line 1212 – 1214: it is stated “Numerical compliance with dose criteria alone should not compel acceptance or rejection of a near-surface disposal facility, further consideration should be given ………of sensitivity and uncertainty”. While we understand that numerical dose limit shall not compel rejection of a near-surface disposal facility; yet the dose limit of 1 mSv/y is a regulatory limit and cannot be exceeded, in this case the designer would either reconsider the facility design or the waste inventory, etc. to comply with the dose limit.
Line 1273-1274 of subsection 4.2: again the dose constraints is used here. Please comment # 6 above.
Line 1441-1442: While the statement is still correct and valid, I suggest adding the “waste form” after the radionuclide content.