CNSC’s EA report on the Chalk River Mound -failure to consider exemption levels for abandonment

CNSC here is ignoring its own regulatory requirements.  Radiation levels in any waste disposal facility must be compared to the regulatory requirements in the Nuclear Substances and Radiation Devices Regulations.

Section 5.1 (1), Abandonment or Disposal

“A person may, without a licence, abandon or dispose of a radioactive nuclear substance if the activity or the activity concentration of the substance does not exceed

(a) its exemption quantity;

(b) its conditional clearance level; or

(c) its unconditional clearance level.

The NSDF “Licensed Inventory” quantities for nearly all isotopes exceed the exemption quantities, generally by many orders of magnitude, e.g., by 3.65 million times for radium-226, 7.57 million times for uranium-238, 6.88 million times for uranium-234, 2.7 million times for thorium-232, 5.07 million times for plutonium-239/240, 303 thousand times for iodine-129, 171 thousand times for carbon-14, 296 thousand times for uranium-235 and 530 thousand times for thorium-230. 

Even when “averaged” over the estimated NSDF total waste mass of just under a million tonnes (9.57E+08 kg), the activity concentrations of carbon-14 and iodine-129 alone exceed the unconditional clearance levels.  The “sum of quotients” for all the NSDF isotopes with half-lives greater than 1600 years (see the definition in section 1 of the Regulations) would exceed the unconditional clearance levels by a factor of five.

The unconditional clearance levels in Column 2, Schedule 2 of the Nuclear Substances and Radiation Devices Regulations are also found in IAEA Safety Standard RS-G-1.7 (Application of the Concepts of Exclusion, Exemption and Clearance). That document says “Doses to individuals as a consequence of these activity concentrations would be unlikely to exceed about 1 mSv in a year.”  The 5-fold excess of the unconditional clearance levels in the NSDF at 1600 years would be equivalent to a dose of about 5 mSv in a year.

Furthermore, as former AECL staff have noted, the higher-activity packaged wastes that CNL proposes to put in the facility would grossly violate the Regulations. 

Consider cesium-137 (Cs-137).  In the Waste Acceptance Criteria for the NSDF, the proposed limit for “leachate-controlled” packages containing Cs-137 is 10,000 Bq/g. For a Cs-137 package to decay by a factor of 100,000 and reach the unconditional clearance level would take over 16 half-lives – 16.61 to be precise.  With Cs-137’s half-life of 30.17 years, it would take 501 years for a package Cs-137 at the “leachate-controlled” WAC limit to decay enough to be released from regulatory control and abandoned – far beyond the proposed 300-year institutional control period. 

A package of plutonium-239 would take 288,380 years, uranium-233 would take 1.37 million years, and so forth.

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