The November 10, 2007, Dallman 31 explosion was caused by the failure of two sets of valves, which set off a series of events over the span of 37 seconds that caused the release of hydrogen resulting in the initial blast in the turbine room. The subsequent fire caused by this blast transferred to the adjacent transformers, which were damaged by falling debris.
Throttle valves, also known as stop valves, which isolate the flow of steam to the turbine, failed to close completely on Unit 31. This failure in closure was caused by a build-up known as "blue blush," which is a type of high temperature oxidation. Another set of valves, known as governor valves, which control the flow of steam through the turbine and regulate generator output, failed to completely lower into their seats.
Based on what has been learned from the Unit 31 failure, CWLP engineers have outlined a series of recommendations to prevent future system failures like those that contributed to the Unit 31 explosion. The recommendations involve making physical changes to the turbine control system, throttle valves and governor valves. Siemens, the original equipment manufacturer, is conducting a study into this. Also recommended were procedural changes for unit start-up and work orders, as well as additional training for all operating positions at the plant.
CWLP's report on the explosion is available on this website. Also available is the executive summary of the report issued by Exponent, the firm hired by CWLP to study the causes of the explosion. A full copy of the Exponent report is available at the City of Springfield City Clerk's Office.
To open and view a PDF document, your computer must be equipped with Adobe Acrobat or Adobe Acrobat Reader. You can download a free copy of Adobe Acrobat reader by clicking on the icon below.
Last Updated:
05/07/08
Top Electric Division Generation