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| Hope Creek Containment Building |
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| wlrun3@aol.com:
--- Quote from: rlbinc on Aug 09, 2007, 01:30 ---BWR Containments... Mark I is the Nitrogen inerted Drywell and Torus. The Lightbulb and the Donut inspired this design. These are inside an unremarkable pole barn called a Reactor Building. They are found at BWR 2s, 3s, and 4s. Dresden, Quad Cities, Pilgrim, Duane Arnold, Monticello and almost every body else have these. Mark II is the vertical standpipe containment. They are also Nitrogen inerted. These are found at BWR 5s. In the Mark I and II the Drywell IS the Primary Containment. LaSalle, Columbia, NMP 2, and Susquehanna have these. Mark III is the horizontal vent containment. These have a Drywell inside the Primary Containment. These are NOT inerted, you can tour the Primary Containment at power and look down (and hopefully see no bubbles) in the Suppression Pool. since they are not inerted, they have active Hydrogen control systems, such as igniters, mixers, and recombiners. Some have Containment Spray (Clinton, Perry, Grand Gulf) Some do not (River Bend). Why? Heck I don't know. Ask GE. --- End quote --- In the Mark II the vertical standpipes would discharge into a suppression pool. In the Mark I diagonal standpipes would discharge into the torus. Am I right? Please help me understand the phrase "horizontal vent containment" in the Mark III. |
| NucEng for Hire:
--- Quote from: wlrun3 on Aug 12, 2007, 01:53 ---Please help me understand the phrase "horizontal vent containment" in the Mark III. --- End quote --- Follow pathway 11-12-10 on the last page of the below pdf file. High pressure in the drywell pushes down on suppression pool water contained by the weir wall within the drywell, exposing a pathway through the horizontal vents into the suppression pool water of containment. http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf |
| Fermi2:
--- Quote from: wlrun3 on Aug 12, 2007, 01:53 --- In the Mark II the vertical standpipes would discharge into a suppression pool. In the Mark I diagonal standpipes would discharge into the torus. Am I right? Please help me understand the phrase "horizontal vent containment" in the Mark III. --- End quote --- On the Mark 1 NOT exactly. Coming from the Drywell into the Torus there are 8 Downcomers that are open to the airspace in the drywell. The number MIGHT vary, I just know the number from the later BWR 4s. These downcomers penetrate the torus and connect to what is called the Ring Header. The Ring Header is a 360 degree pipe inside the Torus. FRom the Ring Header there are 80 pipes each connect on the air side to the Ring Header and the Open End under water in the Torus. We called these pipes the Spider Legs. IIRC they connected to the Ring Header at about 135 Degrees and 225 Degrees as you looked at the Ring Header. They then left at about a 45 degree Angle then changed directions to straight down. NOW I'm stretching my memory here but IIRC the Tech Spec Torus level was based on maintaining the open end of the spider legs at least 3 feet 3 inches below minimum allowed Torus Level. The Dynamics worked like this Time zero: Big LOCA T+5 Seconds: Steam Entering the Drywell starts forcing the Nitrogen in the Drywell into the Downcomers. T+15 to 25 Seconds: The Nitrogen clears the bottom of the Spider Legs. Drywell reaches Max Pressure. The Nitrogen creates a large gas bubble on the bottom of the Torus which displaces all the water to the top which causes the torus to try to lift. The supports for the spider legs, ring header and vacuum breakers were based on the stresses this caused. The Torus itself was anchored to the floor of the Reactor Building every 90 degrees. T+25: The Water then displaces the gas bubble, Steam from the Drywell starts condensing. Condensate Oscillations and Chugging starts Occurring at the ends of the spider legs causing them to sway. T+30 to 35 Seconds: Drywell Pressure drops below Torus Pressure, Vacuum Breakers on the Top of the Ring Header Open to start transferring the Nitrogen gas in the top of the Torus back to the Drywell Via the Downcomers. You'll actually see these Vacuum Breakers cycling at Random due to Chugging in the Spider legs. By about T+60 seconds at the LATEST you should see Drywell Pressure Stabilize at about 25 Pounds with Torus Pressure at about 23#. How fast it goes down from there depends on how much RHR is available for torus cooling and torus spray. I might be off around 5 seconds on the later numbers. Mike |
| wlrun3@aol.com:
--- Quote from: NucEng for Hire on Aug 12, 2007, 03:22 --- Follow pathway 11-12-10 on the last page of the below pdf file. High pressure in the drywell pushes down on suppression pool water contained by the weir wall within the drywell, exposing a pathway through the horizontal vents into the suppression pool water of containment. http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf --- End quote --- Exactly what I was looking for. Thankyou. |
| Cementhead:
Hope Creeks "can" is like few other Boilers because the original plans had it to built in a highly populated area of North Jersey. Word has it that there will be a fourth unit constructed on the island! Build it and they will come! Cant wait for another round of the Island 500! |
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