Review of recent Canadian Standard on Controlled releases N288'1

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Review of recent Canadian Standard on Controlled
releases N288.1
By T.J. Stocki G. Latouche Sept 15, 2009
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Outline

• Brief overview of CSA N288.1
• Guidelines for calculating Derived Release Limits
  (DRL) for radioactive material in airborne and
  liquid effluents for normal operation of nuclear
  facilities.

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N288.1 Technical Committee (TC)

• M. Grey Canadian Radiation Protection
  Association,
• Toronto, Ontario
• M. Hamlat Canadian Nuclear Safety Commission,
• Ottawa, Ontario
• D. Hart EcoMetrix Incorporated,
• Mississauga, Ontario
• T. Jarv Kinectrics Inc.,
• Toronto, Ontario
• J. Lafortune International Safety Research,
• Ottawa, Ontario
• F. Lemay International Safety Research,
• J. McCulley NB Power Nuclear Corporation,
• Fredericton, New Brunswick
• T.J. Stocki Health Canada,
• Ottawa, Ontario
• P. Thompson Canadian Nuclear Safety Commission,
• Ottawa, Ontario
• A. Trudel TRIUMF,
• Vancouver, British Columbia

• J. Ryan CANDU Owners Group Inc.,
• Toronto, Ontario
• R. Stepaniak AMEC NCL Canada Ltd.,
• Tiverton, Ontario
• P. Davis Atomic Energy of Canada Limited,
• Chalk River, Ontario
• A. Antoniazzi Kinectrics Inc.,
• Toronto, Ontario
• I. Benovich Ontario Power Generation Inc.,
• Pickering, Ontario
• T. Brown Bruce Power,
• Tiverton, Ontario
• H. Carisse Cameco Corporation,
• Port Hope, Ontario
• D. Chambers SENES Consultants Limited,
• Richmond Hill, Ontario
• R. DeCaire MDS Nordion,
• A Division of MDS (Canada) Inc.,
• Ottawa, Ontario

Special Acknowledgement Ed Cooper who passed
away during this work.
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N288.1 Technical SubCommittee (TSC)

• P. Davis Atomic Energy of Canada Limited,
• Chalk River, Ontario
• I. Benovich Ontario Power Generation Inc.,
• Pickering, Ontario
• T. Brown Bruce Power,
• Tiverton, Ontario
• N. Garisto SENES Consultants Limited,
• Richmond Hill, Ontario
• M. Hamlat Canadian Nuclear Safety Commission,
• Ottawa, Ontario
• D. Hart EcoMetrix Incorporated,
• Mississauga, Ontario
• J. McCulley NB Power Nuclear Corporation,
• Fredericton, New Brunswick
• T.J. Stocki Health Canada,
• Ottawa, Ontario
• A. Trudel TRIUMF,
• Vancouver, British Columbia
• L. Pelan Canadian Standards Association,

• S. Wang Canadian Standards Association,
• Mississauga, Ontario
• Valuable contributions also from
• M. Audet Atomic Energy of Canada Limited,
• Chalk River, Ontario
• L. Hillier MDS Nordion, A Division of MDS
• (Canada) Inc.,
• Ottawa, Ontario
• M. Lupien Hydro-Québec Production,
• Trois-Rivières, Québec
• T. Yankovich Atomic Energy of Canada

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Derived Release Limit (DRL)

• DRL for a given radionuclide is release rate that
  would cause an individual of the most highly
  exposed group to receive and be committed to an
  annual dose equal to the regulatory annual dose
  limit.
• This could be from a release to air or surface
  water during NORMAL OPERATION of a nuclear
  facility.
• Uses an Environmental transfer model.

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Environmental Transfer Model.
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How the DRL is calculated.

• DRL calculated independently for air and water.
  E.g. for air
• X9/X0 dose per unit release.

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DRLs
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Parameters

• The standard contains tables and tables and
  Tables (110 pages!) of transfer coefficients and
  some nominal values for some location types.
• There are also example calculations in the back
• Tritium 137Cs released to the air.
• 14C 131I released to the water.

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Sources of parameters. (Annexes)

• Annex A (Default values of transfer factors) is a
  set of pre-calculated parameter values for those
  who will not be using a computer program to
  calculate from scratch. Each table follows the
  equations in the main body of the standard and
  lists its assumptions in the footnotes to the
  table.
• Either there are references to the source
  of data in the footnotes or to a clause in the
  Standard, and then either the clause provides the
  source of data or the corresponding CDG section
  has a reference to the source of the data.
• Annex B is an example calculation using Annex A
  tables - no source data
• Annex C (Dose Coefficients) identifies where the
  tables are taken from (ICRP 72, Eckerman and
  Leggett, OPG study, and a few other minor
  references).
• Annex D (Limiting radionuclides for mixed
  effluents) is a very abbreviated form of CDG
  Appendix D - see CDG for more references.
• Annex E (1/2 lives and decay constants of
  Radionuclides used in the Standard) says its
  form ICRP 72
• Annex F (Hydrologic and aquatic transfer models)
  has various references
• Annex G (Parameter Values for Terrestrial
  pathways ) has references, but CDG is more
  comprehensive (Data for intakes are from an old
  HC 1972 survey, but are going to be updated to
  new data which is from a more recent survey).
• Annex H (The finite cloud and immersion dose) has
  references (ref's for the 2 figures are likely in
  CDG) Kocher 1981 could be updated in future
  volume.
• CDG Candu Owners Group DRL Guidance.

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Radionuclides considered in Standard.

• 3H, 7Be, 13N, 14C, 22,24Na, 32P, 35S, 36Cl, 41Ar,
  46,47Sc, 51Cr, 54Mn, 55,59Fe, 58,60Co, 63Ni,
  65Zn, 75Se, 76As, 82Br, 83m,85,85m,87,88Kr, 88Rb,
  89,90Sr, 90,91Y, 94Nb, 99Mo, 99,99mTc, 103,106Ru,
  103m,106Rh,110mAg, 113Sn, 113mIn, 122,124,125Sb,
  125m,132Te, 125,129,131,132,133,134,135I,
  125,131m,133,133m,135,135m,138Xe,
  134,135,136,137,138Cs, 137m,140Ba, 140La,
  141,143, 144Ce, 143, 144Pr, 147Pm, 152,
  154,155Eu, 153,159Gd, 160Tb, 175,181Hf, 203Hg,
  218Po, 220,222Rn, 225,226,228Ra, 225,228Ac,
  228,229,230,231,234Th, 231,233, 234mPa, 232,
  233,234,235,237,238U, 237, 239Np, 238, 239,
  240, 241, 242Pu, 241, 243Am, and 242, 244Cm.

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What types of facilities does N288.1 cover?

• Old N288.1 applied primarily to CANDU nuclear
  reactors in Canada. (still the focus)
• The environmental pathways make the new N288.1
  applicable also to
• Research reactors
• Radioisotopes processing facilities
• Waste processing facilities (incinerators)
• Reactor types other than CANDUs.

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Canada and its power reactors.
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What doesnt N288.1 cover?

• It does not cover releases from
• Uranium mine tailings
• Permanent geological disposal facilities.
• Other facilities where extensive modelling of
  ground water pathways is needed.
• But it can be adapted to cover parts of these
  such facilities.

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National Organization

• Canadian Nuclear Safety Commission (CNSC)
  regulates the nuclear industry (nuclear energy
  substances)
• Regulatory control is achieved through a rigorous
  licensing system.
• Health Canada plays a key role in protecting all
  Canadians from the risk of radiation exposure.
• HC gathers info on radiation exposure and sets
  guidelines to protect the public.
• HC provides assistance on environmental
  assessments.
• Natural Resources Canada (NRCan) provides
  information and advice on nuclear energy policy.
• Provides policy advice to ensure mining is done
  in a sustainable environmentally safe manner.

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National Organization.

• Atomic Energy of Canada Ltd (AECL) builds CANDU
  reactors.
• Normally supplies medical isotopes to the world.
• Dept. of Foreign Affairs International Trade
  oversees relations with IAEA.
• Deals with various treaties (NPT, CTBT, etc)
• Other departments..

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Industry.

• AECL builds reactors.
• MS Nordion produces medical isotopes.
• Mining.
• We have various research reactors, two large ones
  and a few slow poke.
• We have 20 of power reactors in Canada.

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Representative person

• N288.1 uses the representative person
• an individual who receives a dose that is
  representative of the more highly exposed
  individuals in the population.
• It is equivalent to, and replaces, the average
  member of the critical group as per ICRP 101.
• The representative person, who is almost always a
  hypothetical construct is used for determining
  compliance with dose constraints.

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Example of Limits Setup for radioactive releases
at a Canadian NPP

• Internal Investigation Level (IIL) are placed in
  that case at the high end of normal releases
  (97.5 percentile)
• DRLs, AL and IIL will be different from site to
  site
• Ref Environmental Action Levels for Bruce
  Powers, June 25, 2008

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Example for a four reactor plant.
Note ILL is an internal number for the facility
to use.
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Regulatory limit values.(Action Levels)

• The DRL is calculated and an action level is set
  at a small fraction of that value (usually 10 of
  the DRLs at Nuclear Power Plant).
• If an action level is reached, it may indicate a
  loss of control of part of a licensees
  environmental protection program triggers a
  requirement for specific action (reported to
  CNSC).
• Action levels are an early warning system to
  allow the licensee to take action before the
  public dose limits are exceeded.

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Administrative levels or Internal Investigation
Level

• Administrative levels or Internal Investigation
  Level are based on operational experience and are
  lower than the Action level.
• Administrative levels or Internal Investigation
  Levels provide an internal warning of anomalies
  in monitoring data.
• They are specific to discharge points
• Exceedance of an Administrative level or Internal
  Investigation Level triggers an appropriate level
  of review and possibly action.

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Specific questions

• Use a Environmental transfer model based on
  transfer coefficients.
• The standard gives default values for 3 or 4
  regions in Canada, but the user can use site
  specific and is encouraged to do so.
• Gaussian plume is used, if needed.

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Specific questions Atmospheric Transport

• Uses a Gaussian plume model based on sector
  averaged model (Pasquill Smith 1962)
• Takes into account vertical dispersion and
  building wake effects.
• Also uses a semi-infinite cloud model or a finite
  cloud model for air immersion.

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Conclusion.

• Gave you a brief explanation of the standard.

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Questions?

• Thanks for listening!