How would the NSDF leak?

Canadian Nuclear Laboratories (CNL) – run by a consortium of profit-making multinational companies – is seeking comments on its proposed “Near Surface Disposal Facility” for a million cubic meters of radioactive waste at its Chalk River facility along the Ottawa River.  CNL’s draft environmental impact statement (EIS) describes several ways that contents of the proposed “engineered containment mound” of radioactive waste could leak into the Ottawa River.

During operation…

1.  Wastes being added to the mound would be exposed to the elements.  Rain and melting snow would leach radioactive contents down through the mound.  Different radioactive elements would leach at different rates depending on how strongly they were bound to the wastes. Radioactively contaminated leachate would be collected in a system of pipes and pumped uphill to a water treatment plant. Some but not all radioactive contaminants would be removed prior to releasing the treated leachate into wetlands that drain into the Ottawa River. Table 3.5.3-1 on page 3-23 of the draft EIS shows levels of different radionuclides in leachate, and radionuclides that would be discharged to wetlands from the water treatment plant.

2. Tritium as radioactive water would leach in very large amounts from the mound Tritium – a radioactive form of hydrogen with a half-life of 12.3 years – is readily taken up by living organisms and incorporated in body tissues.  When tritium decays it emits “beta radiation” damaging to DNA and other cell constituents. Tritium is part of the water molecule and cannot be removed by water treatment. The draft EIS estimates that tritium in leachate could emit as much as 9 million beta particles per liter per second, and it says that measures would be needed to reduce this to 7 thousand (the current Ontario drinking water standard).  Untreated tritium would be discharged to wetlands, move freely towards the Ottawa River, be incorporated in fish and other aquatic life, and enter drinking water supplies. Large quantities of tritium would also be released from the dump as water vapour.

3. Other toxic substances such as PCBs leaching from the mound would be only partially removed by water treatment. Table 3.5.3-2 on page 3-25 shows that treatment would only partly remove non-radioactive toxic compounds in the wastes such as lead, PCBs and dioxin. Measurable amounts would be released to the environment.

4. Heavy storm events would erode the mound’s surface and wash toxic substances into low areas. Highly contaminated water washing off active dumping areas would be pumped to the water treatment plant. Less contaminated water would be pumped to three storm-water management ponds around the perimeter of the facility and be discharged to adjacent

wetlands.  As these wetlands are already contaminated by existing nearby leaking radioactive waste

areas, the draft EIS explains (page 3-57) that ponds would provide only “basic” containment of sediments before their contents were released.  Pond discharges would be monitored for radiation only twice a year.

5. The capacity of storm-water ponds would be exceeded during extreme rainfall events or snowmelts. The draft EIS (page 9-2)says that pond overflow “would be conveyed by inlet and emergency outletstructures adjacent to the surface water management ponds,” presumably to be released directly into adjacent wetlands.

6. Clearing 34 hectares of mature forest and discharging waste water would impact wetlands.  The existing forest recharges adjacent wetlands.  Loss of the forest’s infiltration and recharge capacity would tend to dry out these wetlands and expose their radioactive contents (such as tritium, strontium-90 and carbon-14) to erosion. The draft EIS notes (page 5-202) that discharges from the water treatment plant “may cause changes to water levels, flows, and channel/bank stability, and scouring of the wetland, affecting water quality at downstream locations.”

7.  Other possible ways the facility might leak during operations (not described in detail in the EIS)include pump failures during extreme storm events with loss of electrical power, improper installation of the base liners, puncture of the base liners by heavy or sharp materials, melting of liners by radioactively hot materials, and blockage of the leachate collection system.

After closure…

1.  Wastes in the mound would be re-exposed to the elements when the top cover fails.  After waste dumping ended the leachate collection system and water treatment plant would be shut down, and a top cover placed over the wastes. The draft EIS acknowledges that the top cover would inevitably fail with “normal evolution” through forces such as erosion, extreme storms, burrowing animals, root penetration, etc. 

2. Failure of the top cover while the more protected base liners remain intact would initiate the “bathtub scenario”.  Rain and melting snow would again leach the radioactive wastes, but the leachate collection and pumping system would no longer be operational.  Contaminated leachate would be trapped by the bottom liner and accumulate in the space between the mound and the surrounding berm. Leachate levels would rise and spill over along the low point of the berm.

3. Radioactive wastes would flow directly into Perch Creek and the Ottawa River less than 1 kilometer away, essentially forever.  Long-lived radioactive elements such as plutonium and uranium, exposed to wind and water erosion, would flow into the river for thousands to millions of years.  Eventual failure of the bottom liners would also allow radionuclides to move into groundwater.  Table 5.2.3-8 on page 5-155 of the draft EIS estimates that plutonium (Pu) isotopes (Pu-239 and Pu-240) would exit the dump at 21.4 million and 32.4 million Becquerels per year, respectively. The Ottawa River would be permanently contaminated by radioactive wastes.  Countless generations of people drinking its water would be exposed to increased cancer risks.