nuclear-news

Canadian Nuclear Laboratories (CNL) – run by a consortium of profit-making multinational  companies – is proposing to build a“Near Surface Disposal Facility” for a  million cubic meters of radioactive waste at its Chalk River facility along the Ottawa  River. CNL’s final 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 adjacent wetlands (for part of the year) or directly into Perch Lake, which drains into the Ottawa River via Perch Creek. Table 3.4.2-2 on page 3-58 of the final EIS shows levels of different radionuclides in leachate that would be discharged 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 EIS estimates that the tritium in a liter of leachate would emit 140 thousand beta particles per second.  After passing through Perch Lake and Perch Creek, water containing roughly 7 thousand beta particles per liter per second (the current Ontario drinking water standard) would be released into the Ottawa  River, be incorporated in fish and other aquatic life, and enter downstream drinking water supplies. Large amounts of tritium would also be released from the mound and Perch Lake as water vapour.

3. Other toxic substances such as PCBs leaching from the mound would be only partially removed by water treatment.

Table 3.4.2-3  on pages 3-59 and 3-6 of the EIS indicate that leachate from the mound would include a very wide range of  non-radioactive toxic compounds such as arsenic, mercury, lead, chloroform, ethylene dibromide, PCBs  and dioxin. Measurable amounts would be released to the environment.

4. Heavy storm events could erode the mound’s surface and wash toxic  substances into low areas.

The EIS proposes an elaborate system of contact water ponds, non-contact water ponds, surface water management ponds, drainage ditches, and culverts.  Highly contaminated water washing off active dumping areas would flow into a contact pond and be pumped to the water treatment plant. Water washing off “inactive” areas (but contaminated by dust from active dumping areas) would flow into non-contact water ponds, be pumped to a perimeter ditch and three storm-water management ponds.  These ponds would discharge to adjacent wetlands that are already contaminated by existing nearby leaking radioactive waste areas.

5. The capacity of storm-water ponds would be exceeded during extreme  rainfall events or snowmelts.

The EIS (page 3-76) says that “when the probable maximum precipitation flow will exceed the surface water management ponds attenuation capacity,” adjacent emergency outlet structures “will be able to convey this flow.”

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 EIS notes (page 5-278) that waste water discharge to adjacent wetlands and Perch Lake “may cause changes to water levels, flows, and channel and 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 EIS acknowledges that the top cover would inevitably fail with “normal evolution” through forces such as erosion, extreme storms,  burrowing animals, root penetration, etc.  It proposes the “conversion of a largely undisturbed, mature forested area to a permanently fenced, turf-grass habitat that is highly modified (i.e., mown, fertilized and maintained as tree-free to avoid the disruption of roots to the cover structure)” (p, 5-509).

2. Failure of the top cover while the more protected base liners remain intact  would initiate a “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.  A different scenario involves failure of the bottom liner, releasing leachate into groundwater.

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. Table 5.2.3-8 on page 5-155 of the draft EIS estimated that, under the bathtub scenario, plutonium (Pu)  isotopes (Pu-239 and Pu-240) would exit the dump at 21.4 million and 32.4 million Becquerels per year.  Eventual failure of the bottom liners would also allow radionuclides to move through groundwater,. These details were removed from the final EIS, but it is clear that the Ottawa River would be permanently contaminated by radioactive waste, and countless  generations of people drinking its water would be exposed to increased cancer risks.