I recommend you read the commentary at Zero Hedge via the source URL, then check out the schematics at the above URL.
For comparison from NukeWorker.com
Re: Japan’s Nukes Following Earthquake
« Reply #81 on: Today at 11:39 »
Nuclear Renaissance (poster)
You get to primary containment flooding if you have no other reliable injection source to the vessel. Continued station blackout gets you most of the way there - an explosion in secondary containment does the rest.
Earthquake causes loss of grid
Loss of offsite power causes scram, Main Steam Isolation, and diesel generator start
Tsunami wave trips diesels an hour later station blackout
Steam-driven systems are only means of injection it is necessary to stay at pressure to maintain motive force
No AC means no containment cooling HPCI should not be used due to its very high exhaust steam discharge into containment
Level is held low, in part to minimize injection (and resultant RCIC-exhaust containment heatup) and in part to stay on DC-powered level instruments
Containment venting becomes necessary to avoid overpressurizing containment they probably were considering venting early with uncertainty of quake damage to containment
8 hr battery coping time is exceeded RCIC becomes non-functional in auto
Local manual operation of RCIC becomes necessary (news reports said 4 operators were in the reactor building basement), meanwhile level continues to lower, challenging fuel
Hydrogen buildup in reactor building causes explosion, obliterating secondary containment and possibly damaging injection penetrations (most are AC-powered anyway). News reports said there were on Steam Condensing mode after the MSIV closure, which creates a direct vessel dome path to the RHR heat exchangers.
Enter containment flooding.
Outstanding post, Thanks for putting this up. Best explanation of what’s going on that I have read yet.
There is no doubt that there are serious problems over there with these particular reactors, and the fact they are still relatively intact despite surviving both a magnitude 9.1 earthquake and the resultant tsunami is testament to the sound engineering that went into them in the first place.
It sound to me like some of the measures being taken, such as seawater injection for cooling, will probably destroy the internal workings of these reactors and likely require extensive replacement of a lot of expensive components. While it isn’t over yet, this accident is not anywhere near out of control and there still has not been a major radiation release; (and I mean something on the scale of a Chernobyl).
Hopefully this will help calm some of the chicken-little mentality....
Here are the official press releases from the company.
The initial 9.1 quake is down at number 42.
Thanks and bookmark
We need nuclear power now more than ever, and the fear-mongering that the lamestream media is doing just hurts any effort to expand construction of such plants in this country.
Here is what I said:
Hey. Calm down. Have a seat. I just want to talk to you to help you calm down. There are a lot of things to be concerned about, but there is no reason to get crazy about this 750 RADS thing you hear. There are people out there throwing these numbers around, moving decimal points three ways to one side or another, not realizing they are doing it, mistaking millicuries for curies, Rads for millirems, sieverts for grays, and so on. Look. Don't get crazed. When someone tells you that 750 Rads are going to contaminate an area, it is nonsensical. The units are wrong. It is like telling someone they need a kilometer of flour to bake a loaf of bread. It is nonsensical and irresponsible, because it is scaring the crap out of people.
Here's the thing. A Rad measures the amount of absorbed radiation on something. Not the amount of radiation, but the amount of energy transferred to something, typically human flesh. (note, you may hear someone refer to rads and rems...for the purposes of human flesh and discussion, they both mean about the same thing...so we will just stick to "rads" because that is what you hear out there a lot) Basically, a Rad measures EXPOSURE to radiation.
If you hear someone mention curies, millicuries or megacuries, that is an amount of decays of an isotope in a given amount of time. When you know what the isotope is, and you know how much energy or what kind of energy is given off when that particular isotope decays, then you have an idea how much radiation there will be.
When you know THAT, then you can figure out how much exposure human flesh will get in a given amount of time when exposed to certain levels of that radiation, and that exposure is measured in Rads.
Now. Here is the thing. EVERYONE gets exposure to radiation, and when your tissue absorbs that radiation, you get exposed to a certain amount of rads of radiation. We ALL get exposed. The average annual exposure to the average person living on this planet is 310 millirem. That is very, very small. That is .31 Rads, spread out over a year. Think of it as eating a cup of salt. Would it be bad for you if you took a cup of salt, mixed it in a glass of water and drank it in one minute? You bet it would be bad. But if you eat that cup of salt over the period of a year, you would probably be fine, but if you eat that much all the time, you will probably have cumulative problems from it, right? Radiation is the same. If you get it spread out over time, it isn't that bad, your body fixes it, but a fair amount over time might have cumulative effects.
I worked in nuclear medicine for 15 years, and I was allowed to have up to 5 rads (that is 5,000 mrad, but we refer to it as mrem or a millirem) a year of exposure to my body. I could have a lot more than that to my hands, which I probably did. But I was allowed to get up to 50 Rads (that's 50,000 mrad!!!!) over the course of a year to my hands because you don't have much in your hands that can be damaged by radiation. I am still here. And I worked with people who handled radiation at much higher levels than I did, and they are in their eighties now, without a problem.
The have a measurement they use called the "LD50/30" dose. It means, the amount of radiation (Rads) that a person can get at one time, all in one shot, that will give you a 50% probability of being dead in 30 days. That amount of radiation is about 600 Rads, more or less.
Re: March 13 2:30pm EDT update
Fukushima Daiichi 1 - unit is now considered stable, with a normal internal pressure of 353 kPa (51 psi), following seawater injection
Fukushima Daiichi 2 - The normal reactor core isolation cooling system is in use. Fuel rods are covered by about 3.8 meters of water.
Fukushima Daiichi 3 - seawater injection continues; a key water level gauge may be malfunctioning. The gauge in question reads that water levels are around two metres below the top of the nuclear fuel assemblies, which would represent a very serious situation with the risk of fuel damage. Pressure levels have come down from 400 kPa to 250 kPa (36 psi), far less than what was seen in Unit 1 (122 psi) before the explosion.
Re: Analysis following explosion at Unit 3
- containment structure appears intact after the explosion
- pressures were below the reference level of 400 kPa
- Radiation readings on site remained low after the blast, albeit elevated from normal operation. In the service hall the reading was 50 microSieverts per hour. At the entrance to the plant the figure was 20 microSieverts per hour.
The containment structures were designed to manage a full core meltdown with no radiation release to the environment. Recommended reading for those who want to research the engineering side of these 40 year old reactors is at the URL below: