Reason Mag Q1 2014 Seite 32

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THE COOL FACTOR Engineers have found that hydrogen cooled generators have advantages as well as safety challenges combustible mixture of hydrogen and air inside the generator The explosion that fol lowed caused damage to the generator and to parts of the Unit 1 and 2 control room The event was extensively covered by the media showing pictures of the metal pan els that had been torn from the powerhouse walls leaving a gaping hole One headline read Power Plant Explosion Sounded Like a Sonic Boom Earthquake which gives a sense of the magnitude of the explo sion that took place Fortunately no serious injuries were reported and the incident did not present a danger to the community In September 2013 the plant owners website reported that much had been learned in the aftermath of the incident and many positive changes have been made as a result The company owners worked with OSHA Occupational Safety and Health Administra tion while the investigation into the incident was conducted and were in the process of reviewing OSHA s ndings and the citations This incident is considered a highly unusual event with very low frequency but a very high severity However similar inci dents have occurred before In April 1999 at a Florida power station while conduct ing maintenance work on a 375 megawatt hydrogen cooled generator hydrogen was released into the atmosphere resulting in an explosion similar to the one at Plant Bowen Regrettably two casualties and dozens of people were reportedly injured as a result of that event OSHA later reported the work ers had not been informed during a morn ing brie ng that the generator had not been purged as scheduled Steve McGhehey chief engineering technical specialist of the FM Global Chem ical operations recalled that a similar but smaller event occurred some 20 years ago in Kansas involving a 700 megawatt generator In that particular case residual hydrogen in a generator that had been opened for mainte nance exploded and destroyed the generator Of all the gases hydrogen has one of the widest explosive ignition mix ranges with air It has a lower explosive limit LEL at The month of April 2013 was character ized by explosions in the United States The sad event at the Boston Marathon over shadowed the media coverage of a massive fertilizer explosion that occurred in the city of West in Texas two days after the Boston bombing At the same time commercial property insurance and the power generation industries were speculating on a possible cause and extent of the loss from a thunder ous explosion that rocked the fossil red four unit 3 200 megawatt Plant Bowen in northwest Georgia earlier that month The Plant Bowen owners website reported that Unit 2 of the Bowen Plant was undergoing a maintenance outage when the explosion took place The company s inter nal investigation indicated it occurred as personnel were taking steps to prepare the unit for work during a planned maintenance outage which included a multistep process to purge hydrogen from the generator Fail ure to comply with procedures along with a breakdown in communication led to a 32 Reason ISSUE 1 2014 theSCIENCE