Turbine failure case closed

Friday, 7 October 2011

Compensation for Chubu Electric Power Company after a steam turbine failure is to cost Hitachi some ¥9 billion ($117 million). 

 

A low pressure turbine (Hitachi)

The sum will make up for the power that Chubu would have generated from June 2006 until February 2007 while repairs were made to Hamaoka 5. The new Advanced Boiling Water Reactor was in commissioning when vibrations were detected in its low-pressure turbine supplied by Hitachi.

A flashback in the flow of steam led to turbulence and vibration stress that damaged large late-stage turbine blades. In total, some 662 of 840 blades in three low-pressure turbines suffered fractures and cracks in the forks that held them to the central rotor. Part of one blade detached, causing yet more damage.

 

The root cause was a combination of unexpectedly large random vibrations and high-speed reverse flows of steam from the water supply heater. The effect was to ruin the huge single turbine-generator set that was meant to have produced some 1380 MWe for Chubu to sell to its customers.

 

After the problem came to light in June 2006, Hitachi began a program of examination, study, repair and re-engineering. Hamaoka 5 eventually went into service in February 2007, about eight months late.

 

A court case ensued in 2008 and this was closed yesterday when both parties agreed to terms of settlement proposed by the Tokyo District Court. Hitachi is to pay Chubu damages of ¥9 billion ($117 million).

 

Shares in both the companies traded higher on the Tokyo Stock Exchange: Hitachi up 1.9%, and Chubu up 1.4%.
 
Researched and written
by World Nuclear News