Presentation for TRANSSC 20 meeting – June 2010 Project progress on development of system to calculate A1 and A2 and exemption values (SEAL) Presentation for TRANSSC 20 meeting – June 2010

Current position - A1 and A2 values A1 and A2 values define levels of activity for Type A packages A1 and A2 values calculated using the Q System – described in Appendix 1 of the Advisory Material for the Transport Regulations (TS-G-1.1) Incorporated into IAEA regulations for safe transport of Radioactive material, Safety Series No 6 (1985) for the first time and in all IAEA regulation after These values were revised for the 1996 Edition of the IAEA Transport Regulations to be consistent with the 1990 Recommendations of ICRP (ICRP 60)

Course Introduction (RADSAFE) The Q system Q values calculated assuming accident conditions for five scenarios: QA - External  dose (no shielding assumed) QB - External beta dose (partial shielding assumed) QC - Inhalation dose QD - Skin (and ingestion) dose QE - Submersion (immersion) dose A1 (special form) = min(QA, QB); A2 (non-special form) = min(QA, QB, QC, QD, QE) General assumptions Exposure is once in a lifetime Effective whole body dose of 50 mSv Organ equivalent dose of 500 mSv External exposure at 1 m for 30 minutes

Exposure pathways in the Q System 34575

Current (1996) A1 and A2 values Calculated by 3 consultants, using separate programs and spreadsheets, for QA, QB, QC and QD (QE) Data used in the calculations taken from: ICRP 38 – energies and intensities of emissions ICRP 68 – dose coefficients Methodology based on original Q system by Goldfinch and Macdonald (CEGB), and other relevant publications

Course Introduction (RADSAFE) Exemption values IAEA BSS exemption values based on methodology given in EC RP-65 report (1993) Did not explicitly address transport scenarios Earlier study looked at range of transport scenarios (e.g. driver delivering packages) Found almost all within order of magnitude of BSS values IAEA transport regulations adopted IAEA BSS values Exemption values for radionuclides not included in BSS but in TS-R-1 (about 100) were calculated separately IAEA transport regulations have more radionuclides than given in BSS and where not given were calculated using RP-65 methodology 6

Assumptions and methodology for exemption values Course Introduction (RADSAFE) Course Introduction (RADSAFE) Assumptions and methodology for exemption values Two exemption values: exemption activities (Bq) and the exemption activity concentrations (in Bq g-1) Three types of exposure scenario were considered: Normal use (workplace) scenario Exposures to the public arising are adequately covered by this scenario Accidental (workplace) scenario for incidents occurring during the routine use of radionuclides Disposal (public) scenario for exposures after disposal of a source Both normal and accidental situations IAEA transport regulations have more radionuclides than given in BSS and where not given were calculated using RP-65 methodology 7

Assumptions and methodology for exemption values Course Introduction (RADSAFE) Course Introduction (RADSAFE) Assumptions and methodology for exemption values Two dose criteria, applied to critical group Annual dose of 10 µSv y-1 for normal situations Annual dose of 1 mSv y-1 (with a probability of 0.01) for accidental situations Annual dose of 50 mSv y-1 to the skin for deterministic effects No collective doses Six different waste forms (solid, liquid and gas) Both external irradiation exposure and internal irradiation (inhalation and inadvertent ingestion) are included IAEA transport regulations have more radionuclides than given in BSS and where not given were calculated using RP-65 methodology 8

Current and future ICRP developments and implications for transport regulations New Recommendations published 2007, Publication 103 Revised data on radionuclide emissions published late 2008 – ICRP Publication 107. Nuclear Decay Data for Dosimetry Calculations. Ann. ICRP 38 (3) Revised dose coefficients for workers to be published 2011(?), and for members of the public by 2012(?) New dose coefficients for external exposures to be published in late 2010(?)

Project on A1 and A2 and exemption values Develop a system consisting of a computer program + databases Calculates values using current methodology and data. Revised data that reflect the new ICRP data, when published can be included Can be used to provide values for radionuclides not listed in the regulations, using current data Accompanying report also gives a review of the methodology used and an indication of areas where methodology can be improved A general comparison of values with those in relevant publications

Project progress A prototype of the system called SEAL (System to calculate Exemption and A1 and A2 Levels) has been developed SEAL output has been compared for about 400 radionuclides with TS-G-1.1 values for Q, A1 and A2 values TS-R-1 values for exemption values

Comparison of Q values - QA and QB values QA and QB values (external dose due to photons and betas) were calculated using method developed by Benassai and Bologna (1994) Method could not be exactly replicated. Two main issues: Interpolation Contribution from progeny

QA and QB values - interpolation Interpolation required for: The air mass energy absorption coefficient, mass attenuation factor, build up factor and air exposure to dose conversion factor (QA values) and dimensionless dose and continuous slowing down approximation range (QB values) given for specified energies Benassai and Bologna gives equations and parameters to generate values for other energies. It has not been possible to use these equations However HPA has developed interpolation methods which give results within 10% of those published in Benassai and Bologna report (this applies to single radionuclides i.e. not including contribution from progeny)

QA and QB values – treatment of progeny Benassai and Bologna gives method to include contribution from progeny for QA and QB values. HPA found that values calculated are different to those in TS-G-1.1 for a number of radionuclides. HPA also investigated using secular and transient equilibrium methods for calculating values.

QA values - problem radionuclides Parent radionuclide QA value (TBq) Ratio of QA for TS-G-1.1 to alternative methods TS-G-1.1 HPA calculation method Secular B & B Transient 131Ba 1.6 2.1 5.3 0.8 1.0 0.3 47Ca 2.7 0.9 0.81 2.3 3.0 3.3 1.2 166Dy 34 15 13 26 2.6 1.3 225Ra 12 4.3 1.5 10 2.8 8.0 189Re 32 16 2.0 91Sr 0.84 0.72 1.4 1.8 1.1 Red text indicates a factor of 2 or greater difference between TS-G-1.1 and calculations from other methods.

QB values – problem radionuclides Parent radionuclide QB value TBq Ratio of QB for TS-G1.1 to alternative methods HPA calculation TS-G1.1 Secular B & B Transient 47Ca* 37 0.8 0.79 1.8 46.3 46.8 20.6 225Ra 0.22 0.82 0.26 0.3 0.1 * The Benassai and Bologna report gives a value of 3.7; TS-G-1.1 gives 37. It is thought that this is a transcript error

Summary – progeny for QA and QB values Transient equilibrium method gives closer results to TS-G-1.1 particularly for QA values SEAL can currently include contribution from progeny using Benassai and Bologna and transient equilibrium method so that two methods can be compared In addition we think there is mistake for 26Al – TS-G-1.1 value ten times less than value HPA has calculated

Qc inhalation dose coefficients TS-G-1.1 recommends use of inhalation dose coefficients from IAEA BSS and ICRP 68. However do not match up in all cases. Differences found in isotopes of tritium, carbon, mercury, iodine, nickel, lead, thorium and curium. SEAL uses values given in ICRP 68

Rounding of A1 and A2 values In TS-G-1.1 Q values are displayed to 2 significant figures and A1 and A2 values to 1 significant figure. However the A values displayed are not rounded from given Q values but from the calculations. This process can for certain results cause a slight difference in the calculated number for Q (eg 1.49 and 1.51) which becomes a large difference in the A1 and A2 value. There are currently 13 radionuclides with this problem (108mAg, 211At, 133mBa, 60Co, 150sEu, 150lEu, 172Hf, 32P, 191Pt, 222Rn, 121mSn, 85mSr and 200Tl)

Exemption values Differences between TS-R-1 and SEAL output found for 16 radionuclides Differences have been investigated and all discrepancies resolved. Only outstanding difference is for 139Ce where value should be 10 times less restrictive than value given in TS-R-1 Appendix added to methodology which details amendments to RP-65 on which TS-R-1 values are based

Timescales Report documenting methodology – original deadline was summer of 2009. However we have continued to add to this document during development of prototype. Prototype for DfT to test – April 2010 Next timescale is revision of methodology and final version of system – March 2011