The massive incompetence that permeates to the highest levels of the US Federal Government is breathtaking.   That stupid imbecile Hillary Clinton isn't qualified to start a lawn mower and to think, she would have been a better choice for President than the piece of crap Obama.  Between the nuke in Japan and the libtards in our Gubermint, I'm not sure which one is scarier?  

What would the real world effects be of a breach. I know what hollywood says but what is the truth?

Mongo, Reading your dissertations on nuclear power plant design is very informative but the real entertainment is seeing your avatar alongside it all.
I can just hear you now, "Mongo just pawn in nuclear power plant structural analysis...."
Thnaks for the info though, it is quite helpful.

Most likely fails to account for the actual half life of the released products.

The short half life stuff  is generally the more dangerous.

it is rapidly breaking down and throwing both particle and gamma rays off.

The long half life stuff is not going nearly as fast, so the exposure for a given time is lower.

You can handle Uranium and Plutonium with little hazard there half lives are so long.

134Cs (half life ~2 years) and 131I (half life ~8 days) are far more dangerous.

While Beta particles (electrons or positrons) cannot even penetrate skin, if their sources are inhaled or ingested they can then create damage.

Alpha particles (essentially a Helium nucleus) can have suffusion energy to penetrate into tissue.

Gamma rays (similar to x-rays) are photons and can also penetrate depending on their energy level.

It is also possible to get protons (and a pile of other particle types) from some decay paths, and they can penetrate if they have sufficient energy.

Yay a thread with good info.

Thanks mongo

Time, Distance and Shielding. I seem to recall the RCM's telling me dilution is the solution

Worst case - long term, highly radioactive release.

If the containment is breached, plans would be put in place to contain it.  I'm not sure if that would take days, weeks or months.  They have the whole ocean at their disposal, so they could fill the containment, then feed and bleed it - as water leaks out, just keep making up to it.  If they can keep that core covered with water, rad levels will be substantially lower and releases will be less.  They'll crap up that whole site, but it's a small sacrifice vs. long term rad release.

Very possible.  It could be packed full of mud and junk.  If I were management there, temp pumps, temp hoses - make it happen.  Procedures go out the window to a certain degree and you do what is needed to get water in the core/containment.

Their assigned task.

Anything is possible, however the intakes are generaly underwater, were as debris is focused more toward the top. They are also coverd with a "screen" that is frairly robust...

All I can picture right now is 500 ppl doing a 45 minute pre job breif while the plant is slowly melting around them.. At this point your right everything out the window, I hate to say it, but part of being a nuke worker is understanding that safty to the public comes before your own at times like these...

You should review your information

Ya, we spend fifteen minutes PJBing greasing PMs.  I could imagine what our management would want for a brief in a situation like this.

How far along in the safe shutdown process were they when it blew...does anyone have that info?

Go here and here.  Read the news releases and updates.

Nothing there conclusively says what caused the explosion.  There is mention of a hydrogen explosion.  I can't wrap my head around why something like that would happen, so it's hard to verify that it was that.

I love it when the brief takes longer then the actual job, lol even more so on overtime ...A few months ago, we breifed for about 1 hour on a job that took less 10 mins to do....Id be willing to bet that if something like this was happing at the plant I work at, the one safty coridnator would be writing CRS on the people who were running, just becuse they were running and he has nothing better to do... lol

Do you have an ALARA department?  Ours is a useless bunch.  They rarely get their estimates right.  We get busted for getting LESS than their estimates.  They often don't even know where equipment is, so I basically have to do their estimate for them.

Nobody? Temperature would be okay too, I've got my steam tables around here somewhere...





 

Tag. Thanks mongo.
Txl

The BWR I work at has steam pressure around 1000psig.  Based on operating principles of BWRs, I'd guess they'd be close.

Interesting, thanks.



 

This has turned out to be a pretty interesting thread...thanks man.

I'll be sure to talk with our operations people tonight and see what they think of this whole mess.


thanks again mango.


Fury.

Just heard on the news that they are flooding the reactors with sea water which based on the info posted here so far seems... not so good.

Anyone know how many chapters separate the Sea Water protocol from the "All Hands Abandon Ship!" protocol in the nuclear GMP manual??

I dont believe we have a ALARA department, how ever I know what you mean, most of the time I have to explain things to ppl that have worked there for many years longer then me. Most of the time they just give me the stair when I talk to them about simple things.. I have coined a new term durning my nuclear career, "Selective sense".. this replaces the term comon sense, as its seem the majority, or "comon masses" if you will no longer have event he slightest bit of sense, and there are only a select few left that uphold the basic knolwedge and skill levels that seperate us from apes...

I've read 1000*F., which is 2800PSI more or less.

Way more than 2800 PSIG. The steam tables I've got only go to 700*F and that's already around 3200 PSIG.



 

What are you guys trying to figure out with steam tables?

You already answered the question to my satisfaction anyway.



 

Whoah there kids.  It's not 1000F.  If they're nominal operating pressure is 1000 psi, then the reliefs are probably set about 50% higher.





 

Not quite 50%.  We have 15 safeties that are set in the neighborhood of 10-20% above rated pressure, IIRC.  Some lift before others.  Some have special features for specific plant operating events and parameters.  The details slip my mind.

This is nearly identical to the plant I work at.  You will note the top floor, known as the refuel floor is simply a structural steel shell with sheet metal around it.  I'd guess the building in Japan is nearly the same.  The question I can't answer is why did the top of the buildling blow off.

The absolute worst case scenario is that some type of explosion happened in the reactor vessel and it blew it's lid AND the lid off primary containment AND the refuel floor plugs AND the roof of the building.  This leaves the core essentially exposed to the atmosphere.  I'd rate this as unlikely.

Another scenario is that there was a hydrogen explosion in primary containment, which blow the lid off of primary containment AND blew the floor plugs out AND blew the roof off the refuel floor.  This could leave the core contained in the reactor vessel and not exposed to the environment.  Depending on the result of this explosion, containment could possibly still be filled with seawater, keeping the fuel covered with water.  I'd rate this as possible.

Another scenario is that somehow, someway, their primary containment vent path goes through the refuel floor and somehow, someway that hydrogen ignited and blew the roof off of the refuel floor.  I'd rate this as possible/probable.

There may have been some other unrelated event, but that's not likely with what's on the refuel floor.

The explosion very likely wasn't a steam explosion, which would indicate a runaway reactor that couldn't be shut down.  It wasn't a nuclear explosion, that is pretty obvious.


I'll say it again - if there's that much hydrogen production, fuel damage is likely.

Looks like you may be right, possible meltdown being reported now

Posted Via AR15.Com Mobile

Just thought I'd add a bit of 'why' to the addition boron to the coolant....



Boron poisons the reactor.....



¹⁰B  (~20% isotope abundance) is really good at capturing thermal neutrons, that is, neutrons that you want for the fission process.



Nuclear plants often enrich their boron supplies to near 100% ¹⁰B.





n + ¹⁰B ––>  ⁷Li + alpha  + gamma

Picture of the damage the explosion.  Notice the primary containment is intact.    Blow out panels and build facade are all thats gone.

And this is the difference between knowledge and hearsay.



You posted this picture and explained that the damage has nothing to do with containment.



Another poster in another thread put the exact same thread and stated that the "roof is gone".



The top of that roof is just a weather cover to protect the crane.  It is a sheet metal roof cap constructed just like an ordinary warehouse.  The containment is below that hidden by the outer square walls which also aren't part of the containment.



Basic building construction would tell anybody with a lick of sense that a square building is not designed for pressure.



I would say that you can't determine the status of the containment from that picture since it is completely hidden by the square concrete outer structure.



Also, a leak can be small an not detectable from a picture like that.



 

If it blew the tin roof off, the chances of it seriously breaching the containment are pretty slight IMO.  Since they are still having to vent it periodically, that means it's still holding pressure and therefor is pretty much if not completely intact.  It may not pass a 30min pressure drop test, but it'll do for today.





 

Some questions seeking answers, not challenges in any way.

1) What is the normal operating temperature in the secondary containment? Could they locally spray a cold water mist (sprinkler heads in the secondary containment) to quench some steam in-situ and reduce the containment pressure without venting? I realize the dramatic results that would occur if cold water hit some of the high-pressure steam areas or electronics, but other areas above the wetwell seem like good candidates for quenching if the wetwell has the ability to be pumped down as it rises. I realize that this is an older design, but it just seems like other methods of reducing pressure would seem more appealing to designers than venting the contents. Are there other methods that are off-line due to loss of power?

2) Is this correct? Due to the emergency nature, steam is allowed to vent from overheated primary containment into secondary containment to reduce pressure and improve cooling efficiency. The steam carries with it the hydrogen, cesium, and iodide from the overheated fuel. The hydrogen from the overheated fuel cladding should have been in the secondary containment until release along with the steam. However, it was accumulating in the enclosed area above the containment, either continuously or as a result of venting the steam from secondary containment. Do they intentionally vent secondary containment to the enclosed area above to minimize the spread of contamination? Any guesses as to why did the hydrogen explosion occur there?

3) Is the nuclear fuel pool in the affected part of the building in general use or is that just a staging area only used during refueling?

4) From the injuries and deaths, it seems like the workers were surprised by the hydrogen explosion. Were they unaware of the extent of the hydrogen buildup?

Efforts to manage Fukushima Daiichi 3
13 March 2011
FIRST PUBLISHED: 4.03am GMT
UPDATE 1: 9.35am GMT. Information on seawater injection

UPDATE 2: 1.30pm GMT. Issues related to seawater injection, Change of headline from Venting Fukushima Daiichi 3

Operations to relieve pressure in the containment of Fukushima Daiichi 3 have taken place after the failure of a core coolant system. Seawater is being injected to make certain of core cooling, but two separate malfunctions are hampering efforts.

The news comes one day after the plant's first reactor was effectively written off as a result of a hydrogen explosion and the move to inject seawater to make certain of cooling the reactor core. Two days ago were the earthquake and tsunami that have proven Japan's worst ever natural disaster.

Now Tepco has reported it has not been able to restart unit 3's high pressure injection system after an automatic stop. This left the reactor without sufficient coolant and obligated Tepco to notify government of an emergency situation.
Preparations for potential pressure relief had already been underway for many hours and Tepco manually vented the containment between 8.41am and 9.20am on March 13.

Noriyuki Shikata, director of global communications in the prime minister's office, said the venting operation was expected to cool the containment, noting that "minute quantities of radioactive materials are released." When this occurred at unit 1, the International Atomic Energy Agency said the emission would be filtered to retain radioactive materials within the containment.


Status of water injection
Injection of fresh water mixed with boron to inhibit nuclear reactions was started as soon as venting had been completed. However, water levels continued to fall and Tepco began an operation to inject seawater into the reactor vessel.

In a media briefing at 8.00pm, chief cabinet secretary Yukio Edano stated that while initially the water level had risen, a gauge indicated that this had leveled off, despite ongoing seawater injection.
The Japan Atomic Industry Forum (JAIF) said that a malfunctioning guage means that water levels cannot be confirmed. Meanwhile, pressure in unit 3 has been gradually rising and this would need to be relieved, Edano said, warning that the vent valve in unit three was showing signs of failure and this was interfering with Tepco's efforts.

The GE design does use quenching to control pressure in the primary containment building (am not talking about the reactor vessel).  It needs quenching to maintain pressures at acceptable levels to the design if I remember correctly.





The problem is pumping enough water to cool the core.  And I think they were having problems doing that.  The information is too poor to understand what is going on because it is just sound bites stated by people who don't understand.



I think what they are doing is filling the containment building surrounding the reactor vessel with sea water to keep it cool.  I think the idea is that the thermal mass of the water is enough to keep the thing cool.  I don't know what they will do after that, but it pretty much means the reactor is an economic total loss and will not be restarted.



I don't know if they will circulate the sea water back out to sea or if this is just a temporary measure to keep the reactor vessel cool until they can get the normal emergency systems back on line.  They said it would take days to fill the containment with water so I don't think they plan on dumping the water, just periodically releasing steam.



It is all sketchy and I imagine the people working on the reactors don't need somebody asking them questions to make sure they have the story straight.





 

You can spray the primary containment and the torus.  You can't spray secondary containment.  It's haibitable, meaning people go there often to do tours, work, etc.  You can vent primary containment, the torus and secondary containment through filtered and unfiltered systems.

If you don't have electrical power you can't spray anything.  The systems that provide spray are AC powered.

What do you think they can or should do?

Assess the probability of getting AC power back soon.  If it's not coming back soon and reactor pressure and containment pressure is going up, do everything possible to fill these plants with any water available, including seawater.

Part of the risk of running a plant is the chance that you may have to destroy it to save the public.  The utility company should make that decision quickly and take any and all action needed to keep these cores covered with water.  Seawater will ruin these plants, but will keep them safe until a controlled recovery can occur some time down the road.

My brother was over last night with his kids ( we were fishing on my dock ).  He used to go to this plant for a few months at a time ( there are several units there) and work on control rod drives and HPU's.  He said this was one of the cleanest ( radiation wise ) plants that he worked on.  There are a number of plants in the US that are identical in reactor design, the external details  ( turbine , feedwater areas) are changed up a bit, but the Japanese do a great job of maintaining their equipment.

Sadly, it appears these Fukujima plants are finished.

Bumping this thread.
Thanks for the great info so far.

another view of the damage.

source
http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichi_march14_2011_dg.jpg

With this newest explosion they are saying it is possible that the containment vessel has been compromised.  



What is the main concern now? If this is the case what would be the next step?

I'm active in the 80+ page Japan thread.  It's too hard to keep two up.  Head on over.

Different reactor at a different site.  Sound like they had a H2 fire like the first 2.

Different reactor same site.