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Repeating DOE-HDBK-3010 Experiments for Better ARF RF Data

Introduction. Objective: Determine the Aerosol characteristics of Y-12 uranium metal/alloys under fire conditionsImpact: Confirm postulated consequences from accident scenarios reasonably bound potential releasesFor: 10 CFR 830 Compliance/ Safety SSC determinations Approach: Design and fabricate testing apparatusConduct experiments with Y-12 binary alloy94 wt% U, 6 wt% Nb.

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Repeating DOE-HDBK-3010 Experiments for Better ARF RF Data

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    1. Douglas Clark B&W Technical Services Y-12 April 28th, 2010 Repeating DOE-HDBK-3010 Experiments for Better ARF×RF Data

    2. Introduction Objective: Determine the Aerosol characteristics of Y-12 uranium metal/alloys under fire conditions Impact: Confirm postulated consequences from accident scenarios reasonably bound potential releases For: 10 CFR 830 Compliance/ Safety SSC determinations Approach: Design and fabricate testing apparatus Conduct experiments with Y-12 binary alloy 94 wt% U, 6 wt% Nb

    3. Five Factor Formula Highlighting ARF/RF ARF x RF is Highly Phenomenologically Dependent Most data is determined Experimentally (DOE-HDBK-3010) Data in Broad Classes of Material Stresses Limited Data available Limited Computational Models Available Models are Verified and Validated using the limited data 3

    4. For Uranium Under Fire Conditions ARF/RF values presented in DOE-HDBK-3010 Based on test data taken in 1965, 1970 &1980 Limited data sets and very few tests Anomalies in data / Disparities in Results Some data of questionable integrity Conservative approach bounds suspect data Relied upon for Nuclear Safety Analysis 4

    5. Previous Tests Airborne Release Fraction (ARF) = % of material made airborne Respirable Fraction (RF) = % of material < 10 µm in diameter Carter and Stewart Alpha-phase uranium metal chips 95th percentile ARF?RF (30 µm AMAD) 3.5E-4 Median ARF?RF (30 µm AMAD) 1.1E-4 Elder and Tinkle Beta-phase stabilized depleted uranium penetrators Indoor Tests (2 hour – heated air) Maximum ARF?RF 4.0E-5 Median ARF?RF 2.0E-5 Outdoor Tests (3 hour – 10 loads of wood) Maximum ARF?RF 5.7E-4 Median ARF?RF 3.6E-4

    6. What is Niobium’s Role in Binary Niobium is only soluble in gamma phase uranium, freezing the properties of the gamma phase at room temperature. Improved ductility Increased creep resistance Slows oxidation of Uranium At Y-12, Binary is worked to minimize grain size of Nb, thus creating a near-homogeneous mixture to further increase these desirable properties.

    7. Difference between Uranium and Binary

    8. What does Binary do to Uranium Ignition?

    9. Why is ignition important?

    10. The Apparatus

    11. ARF/RF Test Apparatus 11

    12. Parameters Airflow 1 m/s face velocity Consistent with ASHRAE standard workplace air velocities Higher velocity than the predominantly calm winds at Y-12. Temperature Temperature profile within apparatus similar to worst case temperature profile in a Y-12 facility based on fire analysis of a design basis fire event. Preheat Air from room temperature (time zero) to 500 şC (~8 min) before introduction into burn chamber. A HDPE puck will be positioned beneath the uranium. This puck auto-ignites around 450 şC. The oxidation of the uranium, plus the heat of combustion of the HDPE will reach the 750 – 800 şC range before the HDPE burns out and the oxide skin forms on the uranium dropping the temperature in the apparatus to 500 – 600 şC for the remainder of the test.

    13. “Worst-Case Temperature Profile”

    14. Aerosol Sampling Purpose of Heat Exchanger Protects sample media from burn-through (Cools to less than 200 şC) Minimizes water vapor loading of filter media (Temp > 100 şC) Maintains air velocity high enough to suspend particulate > 30 µm AED Cascade Impactor vs. Aerodynamic Particle Size Spectrometer Cascade impactor is temperature correctable to determine size correlation with no calibration required. Cascade impactor was used in previous experiments Spectrometer cannot take gas > 40 şC Cooling combustion gas to < 40 şC produces water that scrubs the aerosol and results in differential sedimentation before aerosol sampling. Once contaminated with uranium, there is no way to recalibrate the device. Beaker Leaching Allows delayed neutron counting to detect uraniun in the µg/ml range. This allows > 0.1 mg/filter detection. This allows detection of ARF?RFs > 1E-7, covering the range of previous experimental results. No Sieve Analysis Smallest sieve size available is ~30 µm AED

    15. Sampling Equipment

    16. Technical Challenges Custom fabrication of apparatus using stainless steel was delayed due to the economic downturn. Small machine shops went out of business or had down time. Typically scrap pipe from large jobs would have been used to fulfill orders as small as ours, but there was little scrap available. Desired Sampling Temperature of 100 – 200 şC is higher than the activation temperature of most fire protection systems. Exhaust through fume hood with ESFR sprinklers could set off sprinkler system Exhaust too close to IR detectors could set off fire alarm “Burning” uranium has toxicity implications that led to smoke testing and other means to ensure all particulate is contained. 10 CFR 835 Compliance extended to depleted uranium IH concerns resulted in significant modifications to the equipment for worker protection (e.g., hot surfaces)

    17. Progress in FY2010 Modified Apparatus: Incorporated additional thermocouple ports Overcame technical challenges (e.g., various worker protection items added and flow restrictions removed) Completed leak-tests Finished work control/authorization steps Added additional sampling runs to use all available funds Funding increased from $ 10 K in FY10 to $ 50 K Total project expenditure ~ $ 100 K (FY09 & FY10)

    18. Future Activities – Tentative Dates March – September 2010 Burn Binary Alloy Process Binary Aerosol Sample Media April – September 2010 Analyze Results Prepare Report December 2010 – March 2011 Submit paper for publication in Journal of Nuclear Materials Complimentary NSR&D proposals Forklift Burn Test to adjust worst-case temperature profile. ARF/RF for Uranium containers may lead to better sampling techniques

    19. Importance to DNFSB DNFSB Recommendation 2004-1 Consider Nuclear Safety R&D essential for DOE to maintain and improve the Technical Basis for Nuclear Safety Importance heightened since DOE has unique non-reactor nuclear operations Little overall DOE Progress, to date New Facility design’s based on Old Data 19

    20. Importance to DNFSB (Cont.) NNSA has begun active program NSR&D Working Group (NA 121.1-1, Helmut Filacchione) Coordinates and reports NSR&D across sites Administers small special fund 20

    21. Conclusions NSR&D funds have allowed us to test Binary for ARF determination. This completes the ARF?RF data set for all three metallurgical phases of uranium (phase-stabilized). [Carter and Stewart – alpha phase, Elder and Tinkle – beta phase, Y-12 – gamma phase] Demonstrates key attributes of Y-12 materials under design basis accident conditions. Provides necessary data for compiling a model of uranium oxidation through each of the metallurgical phases. This testing is critical to supporting the Uranium Processing Facility and Consolidated Manufacturing Complex. By demonstrating that the alpha-phase and gamma-phase stabilized uranium respond like the median ARF?RF in DOE-HDBK-3010-94, then Y-12 can avoid unnecessary controls and equipment. This data supports future efforts to revise DOE-HDBK-3010-94 This data also is critical for future phenomenological modeling.

    22. Questions?

    23. 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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