Event
- Event ID
- 521
- Quality
- Description
A technical failure in the High-Pressure turbine blades caused high vibrations in lubricating oil pipes. Some pipes broke off and the oil leak caught fire from hot surfaces. Also the generator's hydrogen leaked out and exploded.
The fire caused the loss of control air and electrical power of several safety-related components: for instance, two turbo-blowers and main heat exchanges were inoperable The fire also affected a main circulation water pipe expansion joint causing outpouring of sea water which caused the flood of the lower levels of the turbine and reactor buildings- Event Initiating system
- Classification of the physical effects
- Hydrogen Release and Ignition
- Nature of the consequences
- Macro-region
- Europe
- Country
- Spain
- Date
- Component involved
- H2 coolant system
- Failure mode
- rupture & ignition
- Initiating cause
- conventional component failure (turbine-generator)
- Root CAUSE analysis
The explosion was caused by turbine vibrations which led to rupture of a fastener beating of the turbine shaft.
- Root causes
- Date entry in HIAD
- 01/01/2017
Facility
- Application
- Power plant
- Sub-application
- Nuclear power plant
- Hydrogen supply chain stage
- All components affected
generator, HP turbine, turbine blades, oil, hydrogen
- Process pressure range [MPa]
- low to medium pressure (below 2 MPa)
- Location type
- Confined
- Location
- industrial area
- Operational condition
- Pre-event occurrences
A technical failure in the HP turbine blades caused high vibrations in lubricating oil pipes. Some pipes broke off and the oil leak caught fire from hot surfaces.
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
- Currency
- $
- Property loss (onsite)
- 100.000.000
- Post-event summary
Fire damaged one of the 2 turbine generators.
The turbine vibrations also led to rupture of a condenser intake pipe, with an ensuing flood that unlashed an estimated total of 4000 cubic meters of water in lower floors of the turbine and reactor buildings.
The extent of the damage is estimated at $ 100 million.- Emergency action
It took 4 hours to bring the fire under control, When the fire was extinguished 2 of the 4 gas circulator systems and 2 of the 4 main heat exchanger systems were knocked out and 2 RHR systems in the reactor basements were disabled by flooding.
Lesson Learnt
- Lesson Learnt
Generic lesson learnt from major Nuclear Power Plants accidents can be found in
IAEA, Experience gained from fires in nuclear power plants: , IAEA-TECDOC-1421
Available at https://www-pub.iaea.org/MTCD/publications/PDF/TE_1421_web.pdf
In-depth data
- Release type
- gas-liquid mixture
- Involved substances (% vol)
- H2,
oil - Release pressure [MPa]
- 0.4
- Probable IGNITION SOURCE
- Explosion type
References
- Sources categories
- IAEA
- Reference & weblink
IAEA, Experience gained from fires in nuclear power plants: Lessons learned, 2004, IAEA-TECDOC-1421
Available at https://www-pub.iaea.org/MTCD/publications/PDF/TE_1421_web.pdf
(accessed July 2024)WIKIPEDIA page dedicated to the accident https://en.wikipedia.org/wiki/Vandell%C3%B2s_I_nuclear_incident
(accessed October 2025)WISE International
This event is listed in From T. VIROLAINEN, J. MARTTILA, H. AULAMO, "TURRBINE GENERATORS AT VVER-440 NUCLEAR POWER PLANTS”, in "Upgrading of fire safety in nuclear power plants", IAEA-TECDOC-1014, Proceedings of an International Symposium, Vienna (Austria), 18-21 November 1997
https://www.iaea.org/publications/5310/upgrading-of-fire-safety-in-nucl…
(accessed July 2024)Full report T. VIROLAINEN, J. MARTTILA, H. AULAMO, "TURRBINE GENERATORS AT VVER-440 NUCLEAR POWER PLANTS”, in "Upgrading of fire safety in nuclear power plants", IAEA-TECDOC-1014, Proceedings of an International Symposium, Vienna (Austria), 18-21 November 1997
https://www.iaea.org/publications/5310/upgrading-of-fire-safety-in-nucl…
(accessed July 2024)
