Event
- Event ID
- 278
- Quality
- Description
The explosion occurred in the condenser area of a steam turbine, two hours after the unit tripped due to a stator earth fault.
The stator earth fault had damaged two hydrogen cooler tubes, which allowed hydrogen to pass from the stator casing into the condenser via the condensate system.
The ignition source was thought to be either via a contact with the hot metal of the steam chests or due to an electrostatic spark.- Event Initiating system
- Classification of the physical effects
- Hydrogen Release and Ignition
- Nature of the consequences
- Macro-region
- Europe
- Country
- United Kingdom
- Date
- Component involved
- H2 coolant system
- Failure mode
- internal explosion
- Initiating cause
- conventional component failure (electricity, power)
- Root CAUSE analysis
The INITIATING cause the leak of damaged hydrogen pipes.
Nothing can be said on the root cause, but the fact that the stator earth fault was able to damage the hydrogen pipe may be attributed to a design failure and/or shortcoming in the risk assessment.- Root causes
- Date entry in HIAD
- 28/02/2009
Facility
- Application
- Power plant
- Sub-application
- unspecified power plant
- Hydrogen supply chain stage
- All components affected
hydrogen pipe
- Process temperature range [C]
- Above ambient temperature (50°C to 100°C)
- Location type
- Confined
- Location
- unknown
- Operational condition
- Pre-event occurrences
A stator earth fault had occurred two hors before the incident and damaged the hydrogen coolant system.
- Description of the facility/unit/process/substances
DESCRIPTION OF A "STEAM CHEST"
The steam chest serves as a distribution point for the high-pressure steam coming from the boiler.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Release temperature [°C]
- 25
- Probable IGNITION SOURCE
- Explosion type
References
- Sources categories
- HSE
- Reference & weblink
Event description provided by HSE, original source confidential
