738 lbs of Cl2 released from T-103, the Nash compressor seals, and leaking gasket on the suction piping at the Nash compressor.
Event Time line:
Morning of 2/15/2017 - Shippers prepared for routine maintenance to replace the chlorine loading hoses at each of the six loading stations
Afternoon of 2/15/2017 - Maintenance work complete
6:00PM - Shift change - the new shift began to hook up chlorine cars for loading
6:54PM - The night shift began loading chlorine railcars
7:00PM -The chlorine monitor at the HyPure® Bleach vaporizer alarmed. Operators don SCBAs in an effort to locate the source of the alarm
7:25PM -The chlorine operator received a chlorine alarm at the operating area fence line(east security perimeter fencing, not property line fence)indicating a small amount of chlorine (0.5ppm).
8:08PM - HyPure® Bleach shutdown
8:10PM - Chlorine was visibly identified at T-103. Railcar loading shutdown
8:12PM - Membrane plant shutdown
8:14PM - Membrane compressor was shut down
8:18PM - Agency notifications made. NRC, LEPC (911), and SERC were notified.
NRC Incident Number 1171174
8:20PM - Facility shelter in place alarm was sounded and the Emergency Response Team was assembled
8:29PM - Team dispatched to investigate off site. Slight readings(1.5ppm)at the barge loading facility with no chlorine indicated in the community using hand held monitor.
8:33PM - Follow up call made to 911 instructing to shelter in place
8:35PM - First reading of chlorine at property line fence monitor(south)
8:40PM - Emergency response team suited up to investigate T-103
8:51PM - Received call back from SERC/ADEM
9:33PM - EPA Region 4 called to ask if additional emergency response resources were needed
9:41PM - Received call from the National Guard asking if any assistance was needed
9:50PM - Instructed area emergency management agency (911) to continue to shelter in place
10:05PM - All perimeter fence line (internal and property) monitors show no chlorine
10:14PM - Chlorine readings(portable meter) at River Road confirm no detectable chlorine
1:00AM - Two valves identified as open on chlorine loading header. Shift supervisor closed valves
1:15AM - All-clear alarm was sounded, however process are a chlorine monitors continued to detect small amounts of chlorine with in the plant
7:41AM - All chlorine monitors reported as clear
On the morning of February 15, 2017 loading and shipping operators isolated the chlorine loading system so that routine maintenance could be performed on the loading hoses. Maintenance activities were completed at approximately 5:00 pm and the system was prepared to be returned to service. At 6:00PM the next shift began connecting chlorine hoses in preparation for railcar loading. Just before 7:00PM the operators began loading chlorine railcars. Shortly after initiating loading, the first chlorine monitor/alarm activated in the HyPure® Bleach vaporizer area. The chlorine traveled from the loading header to the Nash compressor and then to the absorber tanks T-103/T104/T105.
At approximately 8:10PM chlorine was released from tank T-103. Once all systems were shutdown (8:14PM) chlorine dissipated while operators continued to search for the source of the release. Agency notifications were made at 8:18PM.
At 1:00AM two valves on the loading header were identified as open and subsequently closed.
Chlorine process area monitors continued to show small amounts of chlorine until the all-clear was given at 7:41AM.
The incident investigation initiated on February 16, 2017 at approximately 6:00AM. The investigation team discussed the time line of events as out lined above and discussed the root/contributing causes of the event.
The incident investigation team reviewed the maintenance activity on the chlorine hoses and the subsequent system start up just before this event. The pre-developed LockOut-TagOut plan for this maintenance activity was precluded from being used due too the work in the area. The alternative plan developed did not include all valves that were adjusted from their normal position during this work. Therefore the documentation to ensure the valves are placed back in correct alignment for normal operation was not adequate. The root cause for this incident related to a lack of attention to detail to return the system to its original condition. The incident investigation team also identified that the start-up check list could be improved.
2.10 Level of Detail LTA,10
Attention to Detail LTA
- Expand the existing pre-developed LockOut-TagOut plan for chlorine loading hose maintenance to incorporate valves outside of the loading station area(chlorine loading header).
- Update the chlorine loading procedure to expand the start-up checklist to include valves outside of the loading station area(chlorine loading header).
- Install an additional mechanism (car seal)to verify valve closure which will ensure the chlorine loading header is isolated from the Nash compressor(complete).
- Counseling of appropriate employees.
- Incident key learnings to be shared across the site.
- Add a liquid switch/automatic valve to the chlorine loading evacuation header.
- Evaluate other locations in the shipping area where a liquid switch might be beneficial.
- Evaluate improvement opportunities to the Nash compressor system to better control pressure balance across the system.
Bleach Area Engineer
Bleach Area Supervisor
Shipping Area Supervisor
Hypo/HyPure Operator (2)
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