FORMIC ACID SPILL/SITE AREA EMERGENCY - DWPF

1
FORMIC ACID SPILL/SITE AREA EMERGENCY - DWPF

• Larry Hinson
• Defense Waste Processing Facility
• Savannah River Site

2
Summary

• 1500 gallons of formic acid drained from a
  storage tank during Lockout removal
• Acid flowed thru drain valve to dike area
• A Site Area Emergency was declared
• Personnel protective actions were taken
• Acid release was stopped by closing tank outlet
  valve

3
Formic Acid System

• Two storage tanks 6700 gallons
• Contained in dike area that holds contents of one
  tank
• Dike area sloped to trench that is covered by
  grating which in turn slopes to sump
• System drain line is hard piped to sump

4
Formic Acid System
5
Formic Acid Dike Area
6
Formic Acid Characteristics

• Clear Colorless, Sharp Pungent Odor
• Effects
• Irritation of eyes, nose lungs
• Ingestion Dig. tract burns, possible death
• Permissible Exposure Limits
• TWA 5 ppm (10 hr/day, 40 hr/wk)
• STEL 10 ppm (15 minute exposure)
• IDLH 30 ppm

7
Event Sequence

• DWPF was in an outage which included work on the
  Formic Acid system
• The Formic Acid system had been drained and
  isolated by procedure Lockout
• Plan Hang L/T, Drain sys. per procedure,
  Realign per procedure, Restore per L/T
• System work was done. Lockout removal system
  restoration were in progress

8
Event Sequence

• The Lockout was released, procedure for
  realigning from drain not completed
• Operator opened tank outlet valve, noted
  discharge from drain valve above floor
• Sump alarm received and locked in
• Operator closed Tank outlet valve
• Supervisor directed drain valve closed
• Continued with L/T removal.

9
Event Sequence

• Upon re-opening tank outlet valve, formic acid
  began draining to sump via tank drain valve
• Drainage not noted by Operators
• No sump alarm since it had locked in on previous
  attempt
• Personnel left area

10
Drain Valve
11
Sump
12
Response

• Supervisor returned noted liquid above grating
  and rising
• Supervisor entered area in boots and closed tank
  outlet valve to stop drain
• SAE declared 45 gallons threshold
• Protective Action Remain Indoors
• Barricaded Site entrances public road

13
Causes

• New Drain/Restoration procedure not coordinated
  with L/T (L/T had step to drain but not restore
  using procedure)
• Turnover didnt cover open procedure
• Inadequate control for opening tank discharge
  valve SAC
• Con Ops contributors
• Didnt stop when first leak found
• Alarm management

14
Lessons Learned

• EAL was relatively new from OA Review
• Alert Threshold 2 gallons
• SAE Threshold 45 gallons
• Vulnerability wasnt recognized
• Limits very conservative Concentration lt1 ppm
  within facility boundary, yet shutdown traffic
  miles away
• Evaluate carefully potential upsets