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Deposition Velocity Issues at Y-12

Deposition Velocity Issues at Y-12. Bruce A Wilson Chief Engineer, Nuclear Facility Safety Douglas Clark Analyst B&W Technical Services Y-12 May 9, 2012. Brief History & Timeline. 2007/2008 DNFSB issues with ARF and Dispersion Modeling Codes

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Deposition Velocity Issues at Y-12

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  1. Deposition Velocity Issues at Y-12 Bruce A Wilson Chief Engineer, Nuclear Facility Safety Douglas Clark Analyst B&W Technical Services Y-12 May 9, 2012

  2. Brief History & Timeline • 2007/2008 DNFSB issues with ARF and Dispersion Modeling Codes • May 2008, agreed upon MACCS2 with DV = 1 cm/s, issued response to Board • WTP letter on DV issued • B&W prepares tech. basis for DV • May 2011 - HSS safety bulletin issued • B&W revises tech. basis to address all items in safety bulletin • Currently in continuing dialogue on technical basis. ?

  3. Response Letter • Included specification of every parameter to be used in dispersion modeling for UPF and consequence analysis for new and existing facilities at Y-12

  4. Attachment to Response Letter

  5. Use and Presentations on DV • DV=1.0 cm/sec used on “parking lot” fires for UPF • Used in first annual update of HEUMF along with MACCS2 and POSTMAX • Presentation by Megan Houchin at November 2010 SAWG meeting • Followed DNFSB staff report on DV at Hanford • Concluded dose would increase by 4.75 from DV=0.0 to DV=1.0 but does NOT change safety classification of controls.

  6. HSS Bulletin and Aftermath • HSS Bulletin issued in May 2011 • Y-12 Design Analysis Calculation (DAC) also issued in May 2011 • DAC was revised in September 2011 to more completely address HSS bulletin • Added DV calculations based on GENII2 • Again revised in November 2011 to address HSS and CDNS comments • Conclusion remained: “Taking into account Y-12 site specific conditions, all calculated DVs exceed 1 cm/s.”

  7. Rev. 2 of the Deposition Velocity Calculation • Discussion of calm wind conditions • Includes particle size analysis and detailed basis for each parameter • Uses 5 years of site-specific meteorological data

  8. Calm Wind Conditions At Y-12

  9. Surface Roughness Estimates for DV only Used AERSURFACE program (Rev. 2 used annual averages) Neglected topographical roughness

  10. Information provided to DNFSB since November 2011 meeting • Dispersion Analysis (MACCS2 and Deposition Velocity): • Agenda DV- Telecon • Agenda – UPF dispersion Parameter Telecon • DAC-F000Y12-F-0005, “Technical Basis for Atmospheric Dispersion using MACCS2 • DAC-FS-900000-A033, Draft Appendix B, “Determination of Atmospheric Stability Category” • Diabatic Wind Profile Under Calm Conditions, White Paper • MACCS2 input files • Single Slide for DV-Sensitivity.pptx • Spreadsheet entitled “UPF-DV-Simplified(GENII2)-Rev2.xls • Surface Roughness – AERSURFACE OUTPUT FILE • WP-PM-801768-A001, Comparison of Modules and Recommendations for Wake Effects and Surface Roughness Coefficients in the MACCS2 and HGSYSTEM/WAKE Atmospheric Transport and Dispersion Models • Meteorology: • EMPO-556, “Oak Ridge Y-12 National Security Complex Meteorology Monitoring System • Pictures of Y-12 West Tower • Proposed DNFSB Staff Teleconference Agenda Y-12 Meteorology Data – Responses • Other Issues: • DAC-FS-900000-A024, “Impact Analysis of Revised Consequence Modeling Parameters (U)”

  11. DV Feeds into Parametric Dispersion Analysis

  12. Parametric Evaluation of Dispersion at Y-12

  13. Parametric Evaluation Range

  14. Parametric Evaluation Recommendations

  15. ??

  16. Current Status (conclusion) • DNFSB letter of April 2, 2012 identified: • “(5) the need to use reasonably conservative values to calculate dose consequences for several accident analyses that may require safety class controls.” • DNFSB report states that the dry deposition calculation is compliant with the HSS Bulletin but uses non-conservative parameters. • Meeting with DNFSB on May 7, 2012 to present 30 day response to letter.

  17. Disclaimer This work of authorship and those incorporated herein were prepared by Contractor as accounts of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor Contractor, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, use made, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency or Contractor thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency or Contractor thereof.

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