Chemical Screening at SRS by Wayne Davis

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Chemical Screeningat SRSby Wayne Davis
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Introduction

• SRS compared its chemical screening method to
  those used at three DOE sites where methods were
  found acceptable in recent OA-30 assessments. As
  a result of this comparison, SRS will implement
  Hanfords screening (basically that proposed in
  the 2004 draft revision to DOE O 151.1).
• This presentation will give an overview of the
  four-site comparison, highlight work done on
  generating NFPA-equivalent Health Hazard ratings,
  and offer perspectives on exclusion criteria for
  dispersiblity, toxicity volatility.

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Current SRS Identification Screening

• Strict interpretation of DOE O 151.1
• Single decision If TQ/TPQ, include in EPHA
• Otherwise, address in Base Program

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Y-12 Identification Screening

• Hazard identification performed by facilities
  (common lab-scale chemicals are not identified)
• If TQ/TPQ, address in EPHA
• If RQ or specified NFPA criteria, retain for
  screening
• If release could exceed PAC _at_ 30 m, address in
  EPHA
• Otherwise, address in Base Program

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LANL Identification Screening

• LANL develops site-specific TQs (LANL TQs)
• LANL TQs are consequence-based (trip PAC _at_ 30 m)
• If LANL TQ, address in EPHA
• Exemptions based upon common use, low
  dispersiblity, and low inventory(lt 1 lb)
• Otherwise, address in Base Program

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Hanford Identification Screening

• Mimics process presented by NA-41 at 2004 EMI-SIG
• If TQ/TPQ, address in EPHA
• If not, make qualitative estimate of hazard
  potential
• Exemptions based upon common use, low
  dispersiblity, low toxicity (NFPA Hlt3), and low
  inventory(lt lab-scale)
• Otherwise, address in Base Program

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Key Attributes of Reviewed Processes

• Hanford
• Uses screening criteria from latest draft DOE O
  151.1
• Uses NFPA Health Hazard rating as a screening
  criteria
• Y-12
• Includes anything that could trip PAC
• Includes fire byproducts
• Additional NFPA Hazard criteria (fire
  instability)
• LANL
• Developed site-specific thresholds based on
  ability to trip PAC (many threshold quantities
  are very low)

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Vapor Pressure

• 40 CFR 796.1950 Vapor Pressure
• - Volatilization, the evaporative loss of a
  chemical, depends upon the vapor pressure of the
  chemical and environmental conditions Vapor
  pressure values provide indications of the
  tendency of pure substances to vaporize in an
  unperturbed situation, and thus provide a method
  for ranking the relative volatilities of
  chemicals Chemicals with relatively low vapor
  pressures are less likely to vaporize and become
  airborne than chemicals with high vapor
  pressures On the other hand, nonvolatile
  chemicals are less frequently involved in
  atmospheric transport, so that concerns regarding
  them should focus on soil water.

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Vapor Pressure
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Vapor Pressure

• Typical Binning of Vapor Pressures
• lt 1 mm Hg VERY LOW
• 1-10 mm Hg LOW
• 10-100 mm Hg MEDIUM
• 100-760 mm Hg HIGH
• gt 760 mm Hg VERY HIGH (gas at room temperature)
• Water
• 17.53 mm Hg _at_ 20ºC (68ºF)
• Gasoline
• 220 - 450 mm Hg _at_ 20ºC

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Partial Pressure

• Pressure of gas mixture equals sum of pressures
  of each constituent alone
• PTotal P1 P2 ... Pn (Daltons Law)
• When dealing with aqueous solutions, subtract
  contribution of water to arrive at partial
  pressure of the material with which we are
  concerned.
• For example, MSDS for sodium hydroxide solution
  typically show that material has a vapor pressure
  approximately equal to water. This is because the
  NaOH contributes no significant vapor pressure

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NFPA 704 Health Hazard
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NFPA 704 Health Hazard
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NFPA 704 Health Hazard

• Note that all materials given a health hazard
  rating of 4 are toxic (either by inhalation,
  ingestion, or skin absorption). Some material
  given a health hazard rating of 3 may not be
  toxic at all but corrosive or very cold.
• We propose that if a material receives a rating
  of 3 only because it is corrosive or cryogenic,
  it may be screened out preferably in the
  Hazards Survey. This would allow cryogenic
  liquids and some dilute acids/bases to be
  screened out.

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Extraordinarily High Toxicity

• DOE O 151.1 (latest draft) readsSubstances that
  are both dispersible and have extraordinarily
  high toxicity (substances having an ERPG-3 or
  equivalent value of 3 ppm or less) must be
  analyzed in an EPHA if the quantity is greater
  than 1 pound.
• If threshold is specified, units should be in
  mg/m3 (or both) rather than ppm only as TEEL list
  converts all values to mg/m3. About 10 of listed
  substances have no conversion back to ppm (e.g.,
  asbestos)

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Extraordinarily High Toxicity

• Based upon review of several AEGLs, threshold of
  3 ppm is too high. AEGL-3 values for nerve gases
  range from 0.00091 ppm 0.01 mg/m3 for VX to
  0.039 ppm 0.26 mg/m3 for Tabun. Several other
  materials of interest fall into this range (e.g.,
  AEGL-3 for beryllium methyl mercury is 0.1 and
  0.2 mg/m3 respectively).
• I suggest a value consistent with high range for
  nerve gases be used (i.e., 0.3 mg/m3)
  otherwise, sites could trip 1 lb limit with many
  substances (e.g., asbestos TEEL-3 2.5 mg/m3).