Ontario Power Generation's Response to the Joint Review

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Attachment 1 to OPG letter, Albert Sweetnam to Dr. Stella Swanson, “Deep Geologic Repository Project for Low and Intermediate Level Waste – Submission of Responses to the Final Sub-set of Package #4 Information Requests”, CD#: 00216-CORR-00531-00143. IR# EIS Guidelines Section Information Request and Response Conventional (diesel engine) emissions are controlled by specifying the engines to meet Tier 2 emission standards and through normal maintenance (GOLDER 2011, Table 8.2.2-1). 2) Potential Implementation of Exhaust Air Filtration The design already incorporates features to minimize air releases through making accidents unlikely, as noted in Section 7.5.6 of the PSR (OPG 2011). It also includes features to control releases to the environment in the event of an accident, including: � underground airflow through repository is at low air speeds (< 4 m/s), and typically the air would need to travel through more than 1 km of drift and shaft before exhausting, so there is opportunity for radioactive particulates to settle out before discharge to the environment; � ventilation through specific emplacement rooms can be turned off by room-end ventilation louvers; and � ventilation to affected underground areas can be turned off once workers have been confirmed to be in safe locations. Calculations were performed to assess the implication on public safety if a High-Efficiency Particulate Air (HEPA) filter system were installed at the DGR ventilation shaft exhaust for use during accidents. A HEPA filter system can remove a significant fraction of the particulates in the air (minimum 99.97% of all particles greater than 0.3 micrometre, DOE 2005). Two underground accident scenarios were selected from Table 7-40 of the PSR (OPG 2011): in-room unshielded waste package fire, and cage fall with container. The methodology for the analyses is described in Section 7.5.3 of the PSR (OPG 2011). Assuming a HEPA filter is employed, the release of particulates from the ventilation shaft was reduced by 99.97%. Note that H-3, C-14 (100% in fire scenarios and 75% in non-fire scenarios), mercury and selenium are potentially present as volatile species, and are assumed not to be removed by filtration. The result for these calculation cases with and without the filter system is given in Table 1. As discussed above, the public impacts without the HEPA filter system are within criteria under postulated accident conditions. The result shows that the HEPA filter system would have little practical effect on the already small public radiological dose. Table 1 also shows that the non-radiological species released from the waste packages are largely removed by the HEPA filter system, as they (except mercury and selenium) are in particulate form. These concentrations are calculated at the nearest Bruce nuclear site fenceline, based on one-hour exposure. It may be noted that practical HEPA filter systems would handle a fraction of the normal ventilation flow rate, e.g., 30 m 3 /s rather than 100 m 3 /s. Reducing the air flow rates during an accident to 30 m 3 /s would not change the public impacts listed in Table 1, but would increase the contaminant air concentrations within the repository and therefore increase the risk to workers. Page 43 of 69
Attachment 1 to OPG letter, Albert Sweetnam to Dr. Stella Swanson, “Deep Geologic Repository Project for Low and Intermediate Level Waste – Submission of Responses to the Final Sub-set of Package #4 Information Requests”, CD#: 00216-CORR-00531-00143. IR# EIS Guidelines Section Information Request and Response Table 1: Comparison of Impacts of Underground Accidents with and without HEPA Filters Scenario Waste type Radionuclide Species Maximum Ratio of Dose to Criteria* - Public Without HEPA Filter * 99.97% of Particulates Removed by HEPA Filter Non-Radiological Species Maximum Ratio of Concentration to Criteria** - Without HEPA Filter * Public 99.97% of Particulates Removed by HEPA Filter In Room Box Compacted 0.003 0.003 0.07 0.003 Unshielded Waste Non-Processible Boxed 0.002 0.002 0.5 0.003 Package Fire Non-Processible Drummed 0.016 0.016 0.2 0.001 Moderator Resin (Unshielded) 0.019 0.018 0.02
Page 2 and 3: Dr. Stella Swanson September 28, 20
Page 4 and 5: Attachment 1 to OPG letter, Albert
Page 74 and 75: Title: OPG’s Deep Geologic Reposi
Page 76 and 77: Table of Contents CLOSURE WALL CAPA
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Page 82 and 83: CLOSURE WALL CAPACITY The shear str
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Page 88 and 89: Title: Potential Inflows through Cr
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Serge Clement 1011170042-TM-G2100-0
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Serge Clement 1011170042-TM-G2100-0
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APPENDIX A Derivation of Conversion
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External radius of liner =
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ATTACHMENT 2 Attachment to OPG lett
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8. Letter from A. Sweetnam to S. Sw
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OPG’s L&ILW Deep Geologic Reposit
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Ontario Power Generation's Response to the Joint Review

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