Event
- Event ID
- 509
- Quality
- Description
An hydrogen explosion occurred within the off-gas system, causing the stop of the sump pump; subsequently both trains of the standby gas treatment system were declared inoperable.
The sump is part of the off-gas system and the secondary containment.
The hydrogen explosion was contained within the system, but the sump pump sustained some damage.- Event Initiating system
- Classification of the physical effects
- Hydrogen Release and Ignition
- Nature of the consequences
- Macro-region
- North America
- Country
- United States
- Date
- Component involved
- off-gas system
- Failure mode
- internal explosion
- Initiating cause
- unknown
- Root CAUSE analysis
INITIATING and ROOT CAUSE are unknown.
The site operations review of the plant performed an investigation, but its report is not publicly available.
- Root causes
- Unknown
- Date entry in HIAD
- 01/01/2020
Facility
- Application
- Power plant
- Sub-application
- Nuclear power plant
- Hydrogen supply chain stage
- All components affected
offgas system, secondary containment, nuclear power plant
- Location type
- Unknown
- Location
- highway or similar
- Operational condition
- Pre-event occurrences
At the moment of the incident it was operating for 271 consecutive days.
- Description of the facility/unit/process/substances
The power plant was of the boiling water reactor type.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Post-event summary
The sump sustained some damage but could be repaired.
- Emergency action
The plant was shut down and placed in MODE 4 to comply with technical specifications of the plant.
Lesson Learnt
- Lesson Learnt
In absence of he root cause investigation it is impossible to deduce specific and generic lessons.
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Probable IGNITION SOURCE
- Explosion type
References
- Sources categories
- NRC
- Reference & weblink
U.S. Nuclear Regulatory Commission, Weekly Information Report - Week Ending September 24, 1999, SECY-99-239,
http://www.nrc.gov/reading-rm/doc-collections/commission/secys/1999/
(accessed December 2020)
