Plant alert: Don`t let erosion/corrosion compromise safety

One year ago, the rupture of a feed-water-pipe section just upstream of the economizer resulted in a fatal accident at a US utility drum-boiler unit. The direct cause of the accident was thinning of the pipe wall, apparently the result of erosion/corrosion. An accident similar in origin and consequences occurred in December 1986 at a nuclear pressurized-water reactor (PWR) unit in virginia. Although such serious accidents are rare, erosion/corrosion is a relatively common occurrence in all types of steam systems. It joins drum-boiler waterwall-tube failures and deaerator cracking as the most extensive and expensive waterside problems encountered at powerplants. The purpose of this alert is to urge powerplant owners ad operators to inspect locations in feedwater and wet steam components that may be susceptible to wall thinning caused by erosion/corrosion. (An extensive list of references is provided for assistance in obtaining background information.)