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Based on the plant values, I surmised that the leak was so bad that the reheater was hurting the cycle more than it was helping. We used the actual changes in bleed steam drain flow rate and the design information on the tubes to determine how much of a leak to create in the computer model.
From Figure 3, you can see the effect increasing moisture has on the MSR TTD. Not only does the first-stage heating steam start out at high moisture, but also after it expands into the MSR shell the moisture content increases significantly.
When we isolated the first-stage reheater the TTD improved by 19°F, and generation increased about 2.5 MWe. I was wrong again! (I always try to be wrong in the right direction). I asked Jeff if he could open and shut the valve another 10 times so we could get some good statistics, but in spite of the doughnuts he did not see the humor so I hi-tailed it out of the control room before I ended up impaled on the traveling screens with all the fish. As a bonus, we did the analysis to tell them if they should fix it now or wait till the next outage.
Just like that distributer coil wire my brother and I missed, sometimes the answer to our problems is staring us right in the face. In this case it was the bleed steam coil drain pump that led us to the problem. Objectivity is often difficult, especially when we are caught up in the middle of an issue and those in charge think they already know what the answer is. Sometimes it helps to call a buddy from far away in order to get a fresh look at the problem. After escaping from Jeff and a waterbox cleaning, I took my 6-pack of Wrigley’s (it is a nuclear power plant after all) and headed back to my clock that would definitely need a good wind.
Mr. Megawatt is Frank Todd, manager of Thermal Performance for True North Consulting. True North serves the power industry in the areas of testing, training and plant analysis. Todd’s career, spanning more than 30 years in the power generation industry, has been centered on optimization, efficiency and overall Thermal Performance of power generation facilities. Todd can be contacted at email@example.com.
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