1 / 19

Minimum Beryllium TQ (Metal or Oxide) for a Low Chemical Hazard Categorization at TA-21 MDA-B

Minimum Beryllium TQ (Metal or Oxide) for a Low Chemical Hazard Categorization at TA-21 MDA-B. J.C. Laul and Terry Foppe* SB-EWM, Los Alamos National Lab P.O. Box 1663 Los Alamos, NM 87545 505-665-9791 jclaul@lanl.gov * Foppe & Associates, Inc LA-UR-12-01183. Objectives.

delores-oriole
Télécharger la présentation

Minimum Beryllium TQ (Metal or Oxide) for a Low Chemical Hazard Categorization at TA-21 MDA-B

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Minimum Beryllium TQ (Metal or Oxide) for a Low Chemical Hazard Categorization at TA-21 MDA-B J.C. Laul and Terry Foppe* SB-EWM, Los Alamos National Lab P.O. Box 1663 Los Alamos, NM 87545 505-665-9791 jclaul@lanl.gov * Foppe & Associates, Inc LA-UR-12-01183

  2. Objectives • Describe the beryllium (Be) discovery inside Enclosure # 9, on February, 2011 • Account for more beryllium unearthed • Describe properties of beryllium and beryllium oxide (BeO) • Bounding scenarios of fire, spill and explosion to calculate concentrations at receptor distances (e.g., site boundary) • Reevaluate chemical hazard categorization (CHC) • Establish minimum TQ for Be and BeO for Low CHC • Verify Low CHC by evaluating an aircraft crash

  3. MDA-B: Incident Description on February 22, 2011 • During excavating a trench (15 ft W x 15 ft deep) in the middle of Enclosure 9, operators observed a significant quantity of beryllium (Be). • 16 glass (Mason) jars from ~30 inches (in.) below grade were excavated from the trench, and then placed in the sorting area. • An unknown number of jars were broken so the material was dispersed in the soil. • Industrial Hygienist removed a jar from the dig face, took to a nearby safe area, and took samples for evaluation. • The Lab analysis showed the wipe sample to contain 40 mg/100 cm2, which is interpreted as a combination of Be powder (i.e., small metal spheres) and dust (loose contamination), and loose soil (i.e, dirt). Proportion of Be powder, Be dust, and dirt is unknown.

  4. Glass Jars shows mainly Be powder/chips

  5. Glass Jars show mainly Be powder/chips; dust is unnoticeable in jars. Blue color is due to blue film

  6. MDA-B: Earlier Chemical Hazard Categorization (CHC) • A bulk sample analysis shows 97.2% beryllium shaving/chip (2mm) and with lead and nickel being the remainder. • From the appearance, Be metal chips look light and flaky in the glass jars. Weight information was not available. • Operators estimated about 16 lb, in 16 jars (~ 1 lb/jar), and so 20 lb is used as bounding amount to revaluate MDAB’s chemical hazard categorization (CHC). • Earlier evaluation of MDA-B is Low CHC, based on inventory of 170 chemicals, including one lb of Be. • How 20 lb of Be inventory impacts the CHC?

  7. Be Properties and Oxidation (Blue Film) • Be metal has a density of 1.85 g/cm3 and MP at 1278 °C . Be metal is hard, brittle and looks gray white. • Be has strong affinity for oxygen to form oxide, oxidation (2Be + O2 2BeO). This oxide layer, called “blue film”, is a thin (a few microns; 1.2% to 8.1% of coating), tight coating on the Be metal. • It serves as a protective layer (vapor-diffusion barrier) that is continuous, non-porous and tightly-adherent. • In fire, Be vapors diffuses through the protective layer (blue oxide) and forms different physical characteristics of white “fluffy” material and leads to oxidation. • The oxidation depends on the temperature, duration of the fire, and the amount of material and its form. Higher the temperature, higher is the degree of oxidation.

  8. Beryllium Blue Film

  9. Beryllium (Be): PAC-1, -2, -3 Values

  10. Selection of ARF/RF Values for Be and BeO and PAC-3 Values

  11. EPIcode: Approved Code in “DOE ToolBox” for chemical dispersion Recommended Parameters: • Release type: Term release for fire and spill, which is modeled as a ground level release and centerline plume provides the maximum exposure to the receptor. • Term release is highly conservative relative to a 5 or 10 MW fire that involves lofting. • Explosive release is evaluated using 6 lb TNT. • Stability Class: F, which is stable and a conservative recommendation. • Wind speed: 1-2 m/sec is assigned for F stability. 1.5 m/sec at 10 m height is recommended based on EPA and DOE chemical practices. • Deposition velocity of 0.3 cm/sec is recommended by EPIcode and DOE guide.

  12. EPIcode: Approved Code in “DOE ToolBox” for chemical dispersion (cont’d) Recommended Parameters: • Release effective height: 0 meter, which is ground level release. • Receptor height 1.5 m, normally chest height and breathing zone. • Release time (RT) and sampling time (ST) of 15 min each as the TWA to compare with the PAC values, although they are defined as exposure up to one hour. • RF =1.0, because ERPG/TEEL-3 assumes total concentration exposure to a receptor. • Terrain Standard: Open country which is more conservative than City terrain • Downwind X-meter: Plume centerline, Y-meter 0.

  13. Be Concentration vs. Distance Plot for Powder/Chips for Fire as Term Release. • Large uncertainty at short distance (10-40 m), so peak conc. is taken at 63 m. • Fire with lofting ( 5 or 10 MW) is 1 or 2 orders magnitude lower than term release, which is highly conservative.

  14. Explosive Release, 6 lb TNT: Be Concentration vs. Distance Plot for Powder/Chips • 6 lb TNT is based on 9-liter bottle of 10% peroxide and 90% diethyl ether. Debris cloud top is 119 m. • Concentration is about constant from 30 m to 100 m. Value is flat up to 70 m.

  15. Hazard Index (HI) • Defined as the ratio of chemical concentration to PAC-3 value at the receptor distance. • For two or more chemicals, this ratio is adjusted with the % proportions of each chemical, and the sum of HIs or fractions (Sum of Fractions [SOF], similar concept used in DOE-STD-1027) should be less than 1.0 for a Low hazard category (i.e., < PAC-3 for both the public and 100 m non-involved worker). • Applied this concept to address the % proportion of physical forms of oxide vs metal

  16. Hazard Index (HI) (cont’d)

  17. Aircraft Crash Perspective • Original MDA-B CHC did not evaluate aircraft crash for CHC consistent with previous CHCs at LANL • MDA-B Nuclear hazard categorization to justify “Below Hazard Category 3” Radiological Facility screened out large aircraft crashes per DOE-STD-3014-2006 based on the crash frequency < 1E-6/yr, but could not screen out small aircraft crashes • Evaluated impact/spill and resulting fire releases • Resulted in HI of 0.058 • About 10% higher than the operational fire HI (0.053) • Bounded by the explosion HI (0.607)

  18. Threshold Quantity (TQ) Limits for Low CHC • Explosive release governs the TQ for Low CHC due to 0.607 HI. • For 90% Be metal and 10% BeO, TQ = (1/HI) x 20 lb = 32.9 lb •  With other % proportions of Be metal and BeO, TQ limits are:

  19. Conclusion • MDA-B was previously categorized as a chemical Low hazard site. • With new finding of 20 lb Be metal and BeO in Enclosure # 9 and depending on their metal vs. oxide percent proportions, TQs range from 32 lb for Be metal to 50 lb for BeO to preserve Low CHC. • Be inventory being excavated and sorted, or in waste containers staged in a single location, must be controlled to less than the TQ values based on the distribution of Be metal vs. oxide in order to preserve the Low CHC. • Hazard Index (HI) is a good approach (similar to SOF in DOE-STD-1027) for CHC when 2 or more chemicals, or physical forms, are involved. • Low CHC was also verified by evaluating an aircraft crash impact plus fire. • This exercise provides important information in establishing an operational procedure to limit the amount in future excavation in order to maintain Low CHC.

More Related