Vandellos II - Essential service water system pipe degradation

On 25 August 2004 at 5:25 AM with Vandellos II operating at rated power, a circumferential break occurs on the neck of manhole EF-18-I when starting EFP01C pump. This rendered out of service one of the two trains of essential service water system (EF) of the plant. The manhole EF-18-I is located in one of the collection boxes of the system (EF-28-Z3). The break occurred as a consequence of weakening of the carbon steel plate by external corrosion. After the incident, on inspection of the affected neck it was seen that corrosion had progressed in an homogeneous way all around the neck, without a previous clear indication of leak, although oozing had been detected before. (author)