50-50 chance of catastrophic radiation leak?

[TennTradition]

It's made with concrete bottom to cool it down because concrete holds water and lime. This helps it cool. They will continue to keep water on it.

It won't melt below that if that's what you're asking?

It's not going to end up in the opposite side of the planet like a China Syndrome.

There is usually water held up in the wet well below the reactor vessel. It may have already vaporized and left the system by now - I am not sure about that.

As for the melting through the primary containment - that is not out of the realm of possibility, as I said above. This is particularly true for reactor 2, where the primary containment may be damaged.

A liner-melt-through (the failure of the primary containment), while possible, wouldn't necessarily lead to the fuel melting out of the facility. It should stay contained at that point on the floor of secondary containment. Of course, that isn't a pretty situation for reactors 1 and 3, where the secondary containment is damaged in the roof, but better than nothing.

I'm NOT saying these things WILL HAPPEN. But, I am becoming more and more concerned that if cooling cannot become more sustained, the risk of more than just a reactor vessel failure may be quickly on the horizon.

 

[TennTradition]

I was thinking more about the relationship of the benefits of the water (cooling) vs the drawbacks of the steam (increased pressure) .. it sounds like they're in uncharted territory now, so maybe nobody knows what the answer is ..

I guess as long as they can keep the primary containment from exploding they will have done as well as you could hope ..

They MUST continue to feed cooling water to the reactor for as long as they can. Yes, this is creating steam that pressurizes the reactor, but even the creation of the steam provides additional cooling (so adding water and venting it off is a fairly effective cooling strategy, even though it means radioactivity release). Just stopping water addition and walking away runs a serious risk of large, off-site consequences. We would go from relying on engineering and physics (though significantly handicapped by the physical condition of the reactor) to luck and hoping that 1) the primary containment isn't damaged and 2) if it is full intact, that it will hold the meltdown (and there are very real technical reasons - of which I am not well enough versed at the moment to explain or defend - to be concerned that even an undamaged Mark I primary containment could fail.

 

[TennTradition]

When would they pack the reactors with sand and concrete to help contain the meltdown(s), or are we already past that point.

We're not past that point. It would be much more preferable to continue working toward cold shut down, though, but that puts the operators at significant risk of injury or death, depending on what happens to the radiation levels.

 

[NEO]

My understanding is that there is a strong belief that a part of reactor 2's primary containment has been compromised to some extent. That information could be wrong, because it can't be confirmed at this point.

I would agree that the vast majority of the radiation is coming from the vented source (and the burning spent fuel pool). However, I'm also highly suspect (based on the suspicions of some of my contacts) that there is some radioactive leakage from the primary containment (beyond the standard design leakage rate of 1%).

Th bigger concern that I have is that if these reactors have to be abandoned due to dangerously high radioactivity levels, a meltdown is highly likely. As he said, the fuel will then fall into the primary containment as a molten liquid. The problem is that there is no guarantee that Mark I primary containment will contain the meltdown at that point. Sandia National Labs has put the probability of liner-melt-through at 42% in the event of a melt-through of the reactor. Those are not favorable odds when you have three reactors that could meltdown. (If all three meltdown, then there would be a 80% chance that at least one would have containment breakthrough if all three melt down, if my math is right and you believe the 42% figure.)

he says this would be no different than the "high pressure crap they're spewing into the atmosphere right now." He says because they are venting directly from primary right now cesium could show up. He says what people don't understand is that what is being vented into the atmosphere is the same stuff that is actually in primary contaiment. The only difference is if there is no leak it is controlled as opposed to uncontrolled if there was a primary leak.

 

[Volst53]

We're not past that point. It would be much more preferable to continue working toward cold shut down, though, but that puts the operators at significant risk of injury or death, depending on what happens to the radiation levels.

At this point the operators have already gave their own health for their country.

 

[NEO]

There is usually water held up in the wet well below the reactor vessel. It may have already vaporized and left the system by now - I am not sure about that.

As for the melting through the primary containment - that is not out of the realm of possibility, as I said above. This is particularly true for reactor 2, where the primary containment may be damaged.

A liner-melt-through (the failure of the primary containment), while possible, wouldn't necessarily lead to the fuel melting out of the facility. It should stay contained at that point on the floor of secondary containment. Of course, that isn't a pretty situation for reactors 1 and 3, where the secondary containment is damaged in the roof, but better than nothing.

I'm NOT saying these things WILL HAPPEN. But, I am becoming more and more concerned that if cooling cannot become more sustained, the risk of more than just a reactor vessel failure may be quickly on the horizon.

As long as they can vent and keep trying to cool it, he says it will not burn through the containment.

If venting somehow stops (which he thinks is near impossible) and they can't keep cooling it and give up ... then yes, all hell is going to break loose and this is going to be very very bad. He honestly wont give me the answer to what will happen if the above takes place and keeps dodging that answer. he says it wont happen. And moves on.

 

[NEO]

There is usually water held up in the wet well below the reactor vessel. It may have already vaporized and left the system by now - I am not sure about that.

As for the melting through the primary containment - that is not out of the realm of possibility, as I said above. This is particularly true for reactor 2, where the primary containment may be damaged.

A liner-melt-through (the failure of the primary containment), while possible, wouldn't necessarily lead to the fuel melting out of the facility. It should stay contained at that point on the floor of secondary containment. Of course, that isn't a pretty situation for reactors 1 and 3, where the secondary containment is damaged in the roof, but better than nothing.

I'm NOT saying these things WILL HAPPEN. But, I am becoming more and more concerned that if cooling cannot become more sustained, the risk of more than just a reactor vessel failure may be quickly on the horizon.

He says you know alot for not working at an actual plant.

Ask if you're a soviet spy?

He's kidding.

 

[TennTradition]

Fire at number 4 appears to be out.

Good news is that the earlier fire (and presumably this one) is being reported now to be caused by pump oil near the pool, not the fuel in the pool. The fire did create enough heat to cause the pool to heat up and lose some coolant. Keeping the spent fuel rods under water is very important, hopefully they can keep it submerged.

 

[TennTradition]

He says you know alot for not working at an actual plant.

Ask if you're a soviet spy?

He's kidding.

I can assure you that I am far from it .

 

[NEO]

Fire at number 4 appears to be out.

Good news is that the earlier fire (and presumably this one) is being reported now to be caused by pump oil near the pool, not the fuel in the pool. The fire did create enough heat to cause the pool to heat up and lose some coolant. Keeping the spent fuel rods under water is very important, hopefully they can keep it submerged.

Have you read if they were keeping fuel rods in that helium cast outside he told me about? he said that was suppose to be 2 miles away.

Were they actually keeping that within the compound?

 

[TennTradition]

As long as they can vent and keep trying to cool it, he says it will not burn through the containment.

If venting somehow stops (which he thinks is near impossible) and they can't keep cooling it and give up ... then yes, all hell is going to break loose and this is going to be very very bad. He honestly wont give me the answer to what will happen if the above takes place and keeps dodging that answer. he says it wont happen. And moves on.

That's why I am worried about radiation levels in the plant. If they have to leave, it will be very difficult to ensure that water continues to flow into the reactor vessels (the flow has stopped multiple times in the past few days and direct human intervention has been required to re-initiate it) or that the vents stay open (valves on the vents of reactor 2 have stuck close several times - admittedly, at least once was human error - a situation that had to be corrected by direct human intervention. My point is that those humans aren't the problem goes unfixed - either indefinitely or until they can get people in to correct it, if possible. During this time, the reactor runs the case of either:

1) in the event of no coolant - drying up, leading to fuel melt down, reactor vessel melt through, and release into primary containment. The primary containment is not guaranteed to hold, particularly if damaged. Liner-melt-through would be possible.

or

2) in the event of a vent closure - the reactor vessel would face over-pressurization which could damage the primary containment upon reactor vessel failure and could lead to liner-melt-through.

Basically, coolant cannot be stopped and periodic venting must continue if we hope to avoid a situation where we have to sit back and *hope* the primary containment systems hold for all three reactors (something that if my math above was correct, would only have roughly 20% odds of actually proving true).

 

[TennTradition]

Have you read if they were keeping fuel rods in that helium cast outside he told me about? he said that was suppose to be 2 miles away.

Were they actually keeping that within the compound?

No, I haven't read about that. I think that he is referring to dry cask storage for fuel rods that have cooled down and are just being stored on site because we have no repository for the fuel, is that correct?

First, reactors 4, 5, and 5 were under maintenance with little (or possibly no) fuel in the reactors. Thus, the spent fuel storage pools in those reactors' secondary containment structures contained A LOT of spent fuel that was still cooling down (from temperatures of about 100 C when first removed from the reactor). I do not think that the rods were cool enough to be removed to secondary storage at this point.

Second, I am not sure what secondary storage is for the Japanese. I think that they reprocess, so the rods may go from the spent fuel pools in the secondary containment structure straight to the reprocessing plant. However, it is possible that they store the fuel in casks on site (which I think is what your friend is referring to). I don't know what the next step is in Japan's nuclear fuel life-cycle.

 

[VOLatile]

Reactor 3 is not overheating ATM, right? It's the one with the MOX fuel, IIRC.

 

[NEO]

No, I haven't read about that. I think that he is referring to dry cask storage for fuel rods that have cooled down and are just being stored on site because we have no repository for the fuel, is that correct?First, reactors 4, 5, and 5 were under maintenance with little (or possibly no) fuel in the reactors. Thus, the spent fuel storage pools in those reactors' secondary containment structures contained A LOT of spent fuel that was still cooling down (from temperatures of about 100 C when first removed from the reactor). I do not think that the rods were cool enough to be removed to secondary storage at this point.

Second, I am not sure what secondary storage is for the Japanese. I think that they reprocess, so the rods may go from the spent fuel pools in the secondary containment structure straight to the reprocessing plant. However, it is possible that they store the fuel in casks on site (which I think is what your friend is referring to). I don't know what the next step is in Japan's nuclear fuel life-cycle.

Yes but he said these should never have been stored so close. he said Southern Co would never allow for them to be within the perimeter.

He has a feeling that when this is said and done there is going to be a laundry list of broken rules that led up to this overall outcome.

 

[JayVols]

TennTradition- still rockin the nuclear thread.

Many deserved kudos. Still awaiting confirmation of your VN Nuclear GURU status. No kdding, you have done extremely well, good sir!
Posted via VolNation Mobile

 

[VOLatile]

TT, could you speculate as to what the conditions are like for the remaining employees at the plant?

 

[Daddy Gee]

the JAIF has put up an update as of 8:00, march 16

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300240000P.pdf

shows 6.3 mSv/h at the station boundary now .. up from .49 mSv/h at 19:00 on march 15 ..



http://english.kyodonews.jp/news/2011/03/78387.html

An estimated 70 percent of the nuclear fuel rods have been damaged at the troubled No. 1 reactor of the Fukushima No.1 nuclear power plant and 33 percent at the No. 2 reactor, Tokyo Electric Power Co. said Wednesday.

The reactors' cores are believed to have partially melted with their cooling functions lost after Friday's magnitude 9.0 earthquake rocked Fukushima Prefecture and other areas in northeastern and eastern Japan.

 

[TennTradition]

Yes but he said these should never have been stored so close. he said Southern Co would never allow for them to be within the perimeter.

He has a feeling that when this is said and done there is going to be a laundry list of broken rules that led up to this overall outcome.

OK - I just wanted to make sure that he was talking about the dry storage casks. I don't know if those are being stored near the reactors or not. It sounds like he has suspicions that they are. I'm not sure if they even have these on site and, if they do, where they store them.

 

[TennTradition]

Reactor 3 is not overheating ATM, right? It's the one with the MOX fuel, IIRC.

Yes, reactor 3 is the reactor with MOX fuel. Though, as it turns out, only the last partial re-loading of the reactor was MOX, with the other fuel rods that were already in place apparently just being uranium. So, that means that the results of meltdown and containment breakthrough would not be as bad as with a pure MOX fuel. David Wright or Ed Lyman, can't remember which, of the Union of Concerned Scientists calculated that the additional radioactive material exposure would only be about 10% due to this MOX fuel. That is, IF the plutonium isn't spread...which is a reasonable thing to assume AT THIS point.

As for the temperature of reactor 3, I do not know the answer. My understanding is that there are still issues of getting enough coolant to reactors 1 and 3. But, the temperature may be under control. I do not know how many emergency ventings they are having to perform.

But, it should be understood that these reactors have been in shutdown mode for less than a week. At two weeks, the heat output will still be enough to boil off 60 gallons of water every minute. And the falloff is exponential, so the evaporation rate at one week (I don't have the number) is still very high. So, providing adequate coolant is still a very serious issue...and remains a complicated matter.


...on a side note...

Jim Walsh, who is an STS fellow at MIT, is on CNN right now criticizing the IAEA for leaving the Japanese operator alone to operate the plant. He is making a reasonable case that the 50 are being hung out to dry and they should be getting direct help and relief from the IAEA.

 

[TennTradition]

TT, could you speculate as to what the conditions are like for the remaining employees at the plant?

No, I really can't. It would be pure conjecture. With the fire at 4, the primary containment damage at 2, the venting at 1-3, and the steam that now appears to be coming off of 3, I would imagine that it is very radioactively hot inside the plant now. They aren't releasing enough information to actually put a finger on it, though, and to estimate it would require more information than we (or even they) have about the condition of the fuel in the reactors and the condition of the primary containment.

--------

CNN is reporting that a Japanese press conference just announced that the remaining workers have been ordered to abandon their stations. If true, that is very bad news.

CNN is being very responsible here, they are trying to see if there was a translation error. I am hoping that the Japanese press conference actually was just saying that the plants had been evacuated from the normal 800 down to the remaining 50.

 

[govols1864]

Why would MOX fuel put off more radiation??

 

[TennTradition]

the JAIF has put up an update as of 8:00, march 16

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300240000P.pdf

shows 6.3 mSv/h at the station boundary now .. up from .49 mSv/h at 19:00 on march 15 ..



http://english.kyodonews.jp/news/2011/03/78387.html

Thanks for the update.

That number is not all that high...but it is at the plant boundary. I wonder how high it is near the control rooms?

As for their estimations of the percentage of fuel damaged, I think that they are only basing that off of how long they think each has been exposed above the water level. Unfortunately, that is a very difficult estimation to make. For example, three years after Three Mile Island, the reactor was opened up and they were shocked to find that the reactor fuel had melted in some areas. The fuel rods were only exposed above the water level for two hours at three mile island. The fuel has been exposed for longer periods at Fukushima. Now...the rods may be better-constructed today. I'm not well-versed in that...but just saying...I don't have any reason to have confidence that the percentages they are giving have any currently measurable basis (they could be too high...they could be too low).

 

[TennTradition]

Why would MOX fuel put off more radiation??

MOX fuel stands for mixed-oxide fuel, or uranium- and plutonium-oxide fuel. The reason that the radiation can be higher is because of the plutonium decay products. The toxicity can also be higher because of the presence of the plutonium...but like I said earlier, plutonium release isn't expected at this point.

 

[govols1864]

MOX fuel stands for mixed-oxide fuel, or uranium- and plutonium-oxide fuel. The reason that the radiation can be higher is because of the plutonium decay products. The toxicity can also be higher because of the presence of the plutonium...but like I said earlier, plutonium release isn't expected at this point.

Thanks. I have a family member who is high up at the MOX project at Savannah River.

 

[govols1864]

Saying on CNN they have suspended operations.