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Anonymous said...

Fukushima 1 actually had (has) an isolation condenser, however the valves were kept closed most of the time during the start of the accident when the power was lost.
Had the valves been kept open... maybe unit 1 would be O now. We really need to find out more what happened, Tepco reports clearly indicate the inappropriate operation of the isolation condenser. Why on earth was the cooling not used?

@dean So it is below the refueling floor and across the building from the fuel pool so about somewhere under the equipment pool. Surprised they are inside the building with the high rad levels.

I saw their chest meters blinking.. not sure on the dose but they do seem to press on ..

Isolation Condenser (IC)

Some reactors, including notably the (E)SBWR series of reactors, have a passive system called the Isolation Condenser. This is a heat exchanger located above containment in a pool of water open to atmosphere. In operation, decay heat boils steam, which is drawn into the heat exchanger and condensed; then it falls by weight of gravity back into the reactor. This process keeps the cooling water in the reactor, making it unnecessary to use powered feedwater pumps. The water in the open pool slowly boils off, venting clean steam to the atmosphere. This makes it unnecessary to run mechanical systems to remove heat. Periodically, the pool must be refilled, a simple task for a fire truck. The (E)SBWR reactors provide three days' supply of water in the pool. [5] Some older reactors also have IC systems, including Fukushima Dai-ichi reactor 1, however their water pools may not be as large.

Under normal conditions, the IC system is not activated, but the top of the IC condenser is connected to the reactor's steam lines through an open valve. Steam enters the IC condenser and condenses until it is filled with water. When the IC system is activated, a valve at the bottom of the IC condenser is opened which connects to a lower area on the reactor. The water falls to the reactor via gravity, allowing the condenser to fill with steam, which then condenses. This cycle runs continuously until the bottom valve is closed

@lilly.. there are so many things just in the first video I ran into.. cracks in walls, broken piping, damaged electrical panels, just to name a few of interest.. anything showing system damage are all good shots..

from what the article said on isolation condensors the water gravity falls to the reactor after the condensation

In some BWRs, such as Fukushima’s Unit 1, an isolation condenser (IC) provides heat removal if the main condenser is unavailable or isolated from the reactor. ICs condense steam from the core and return condensate directly to the core, rejecting the heat to an external pool of water through natural circulation. During isolation condenser operation, the water on the shell side of the condenser boils and needs to be replenished. Makeup water is typically provided from on-site water storage tanks through pumps powered by either off-site power or on-site emergency diesel generators if off-site power is unavailable. Other sources of water—from, say, the fire protection system—could also be used. However, their use will likely require manual actions.

Newer designs, such as those at Fukushima Units 2, 3, and 4, employ a steam turbine-driven reactor core isolation cooling (RCIC) system to control primary system inventory during abnormal transient events, including the loss of off-site power and conditions known as “station blackout” where both on-site and off-site power is lost. Energy from the reactor may be removed through the safety relief valves to the suppression chamber, a toroidal-shaped chamber located within the reactor building that is an integral part of the Mark 1 containments, the kind used by Fukushima Units 1 through 4.

notice on the RCIC systems.. they require power.. which was lost

last ditch efforts lead up to the TORUS.. but it was overwhelmed

I say they are the IC's.. the only other larger tanks on that side are one level done for the heat exchangers..

get photos of the IC and gauges etc.. also.. I wonder if we can see the electrical panels for breaker position...or valve photo's to determine if they were open on the bottom or not..

econtent.unm.edu @lilly.. can you enlarge the link to about 25% and then highlight the area around the isolation condensor and post it here.. it gives some better perspective of where it is located and things around it

@dean will do on the drawing. The paint flaking off, the building has been full of steam for close to 6 months probably made it worse. The predisaster pics showed lots of rust and flaking paint

yes I saw that

watching video

any links to npp accidents in Japan or global gratefully received

true @ lilly

@elainekirk you hear them go off and then stop and it sounded like a couple times it was drown out or covered up.

Anyone know what the loud hissing sound on the video was?

@dean Windows 7 has a snipping tool. I use that to cut a section of the PDF, and either save it or move it to photoshop if I need to do something to it.

I am going though jnes reports and logging all that have an ines rating