meltdown question

[ivymike]

ok, so a neighbor of mine used to work at the Japanese nuclear plant that's having the trouble currently. He's a bit of a blow-hard, and this evening he decided to bend my ear about the reactor. He said that he can't see why they're having so much trouble with it, they must just be trying to save money by not draining the water. I said that it sounds like they're having a heck of a time avoiding melting of the fuel and eventual loss of containment. He responded "all they have to do is drain the water and the fission will stop." I was like "um, no... they need the water in there to slow the reaction and help remove heat" He said "no, it's a fast neutron reactor, and the water is where the fission happens. if you drain the water, the fission will stop, but it'll get hot inside." Anyway, he started doing his "you have no business questioning me" routine, so I left. A quick look on wikipedia convinced me that I was more right about it than he was (boiling water reactor, and water helps to moderate), but it left me wondering whether there were any grains of truth in what he was saying, or things that he could have been told and misinterpreted during a safety course or similar. Are there any reactor designs where draining the water inherently results in stopping the fission?

 

[TheBlacksmith]

I stand corrected. The moderator makes it possible to have fission occur at a fast enough rate to produce usable thermal output. The first "atomic piles" used graphite as a moderator, however, these and most reactors use water as the moderator and coolant.

 

[msquared48]

So... Did the Japanses finally create Godzilla?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[IRstuff]

not yet; only when the core melts through its containment vessel and the material gets into the groundwater and out to sea.


on similar note, consider each reactor as being able to crank out 250MW of power, and assume the dampers are 99.9% efficient. That still leaves 250kW of cooling required to keep everything under control.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[stevenal]

I like how they are announcing they are "pumping in seawater." Aren't the reactors full of seawater yet? And where does the heat go once they are full? They seem to be avoiding the admission that they are actually circulating seawater. Gojira is getting pissed.

 

[IRstuff]

The water, if not refreshed, would boil away. If the water is not circulated, then there would be literal and figurative hotspots as well.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[BigInch]

Sounds like the NRC just said the only ones mixing Scotch and BS, with heavy water, is Tokyo Power.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[BigInch]

Evacuate all within 50 miles is just a little bit different than 10 km!

This looks like its going to be a long, rough ride.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[zdas04]

Last I saw the workers were evacuated to 50 m from the buildings, "m" "km" "miles" its all the same to a talking head.

David

 

[BigInch]

MILES is what the NRC head said, not talking about workers, but the surrounding civies.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[BigInch]

Besides, think about it.

The walls blew off the buildings!
Just how good do you think this could be.

It's a Nuc, not a compressor station, although I wasn't so very thrilled to have seen that happen on a compressor station, at least I knew that the danger had pretty much dissapated at that point.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[pmover]

perhaps the information at this website will be helpful in understanding the situation . . .

http://mitnse.com/2011/03/13/why-i-am-not-worried-about-japans-nuclear-reactors/

http://mitnse.com/

good luck.
-pmover

 

[KENAT]

For anyone in the Santa Barbara CA area...

>
>March 16, 2011
>
>To: The Campus Community
>
>Re: Rapid Response Public Lecture: Understanding the Sendai reactor
>meltdown from a physics perspective
>
>How bad is the reactor meltdown in Japan? Assistant Professor Benjamin
>Monreal, UCSB Department of Physics, will give an overview of
>radioactivity and reactors; radiation health and safety; and the
>ultimate fate of the materials coming out of the stricken reactors in
>Sendai. Why is it worse than Three Mile Island? Why is it (probably)
>not as bad as Chernobyl? How worried are scientists? How worried should you be?
>
>The lecture will be followed by a Q&A session with a panel including
>Theo Theofanous, Professor of Nuclear Engineering in the UCSB
>Department of Chemical Engineering.
>
>Wednesday, March 16
>
> 6:30 PM, 1403 Kohn Hall, UCSB
>
>Seating is *limited* and first-come-first-served. Once the hall is full,
>people will be turned away.
>
>Directions and parking:
>

http://www.kitp.ucsb.edu/outreach/public-lectures/location-and-parking

>

Sadly, I'm working, well obviously not this very second as I'm typing this on Eng-Tips but you get the idea.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[BigInch]

pmover, Exactly. First, I'm not worried about the thing from a personal perspective, as I'm quite far away, but I do have empathy for the situation the Japanese people find themselves in now. Second, about it turning into a bomb. My point is that it doesn't have to. There seems to be pleanty to worry about without reaching that extreme.

"Keep out the weather"? Oh really? When I was doing pipe whip restraints back in the 70's, the South Tx Project guys told me it was more for like keeping out falling airplanes, or some kind of projectile hurled by a tornado. OK, that doesn't leave me with a lot of confidence about what the rest of what the MIT kids are saying, given their apparent propensity for understatement just noted.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[unclesyd]

Back to the problem of dissemination of information on a timely and transparent basis would be beneficial to the operators of the 24 similar reactors in the US. Evidently there is some gotchas in the design. There is several statements about a number of engineers from GE resigning due to their concern on some of the design. There was no mention of any specific problems though they phrased it as many.
It is my understanding that these reactors operate on recirculated Cooling Tower Water and the introduction of Salt Water effectively killing the reactor.

I'm trying to find a report on Chernobyl that actually hoes the results of a meltdown. It shows a very large mass of highly radioactive material in basement below the containment vessel.
The were able to get pictures of it by using an RC toy truck from Radio Shack. They gleaned a lot of information until the radiation killed camera.

I don't know about the helicopter pilots dropping water on the reactors, as the Russian pilots who dumping Boron were all dead within 45 days of the incident, All the solders that are shown pushing the debris back into the reactor were dead in 30 days.

I posted this link before but will post it as it is a synopsis of the of getting the real information from TEPCO. They have not been very forthcoming with the true story at any time. The question now being asked why would this change for the current incident.

http://www.nirs.org/reactorwatch/accidents/nit92.pdf

 

[johnhors]

I received the following in an email today, if true then this is very scary, I attach the document mentioned:-




Paul Joseph Watson and Kurt Nimmo
Infowars.com
March 15, 2011

Infowars analysis: In addition to under reporting the fires at Fukushima, the Japanese government has not told the people about the ominous fact that the nuclear plant site is a hellish repository where a staggering number of spent fuel rods have accumulated for 40 years.

A contributor to the Occupational and Environmental Medicine list who once worked on nuclear waste issues provided additional information about Fukushima’s spent fuel rod assemblies, according to a post on the FDL website.

“NIRS has a Nov 2010 powerpoint from Tokyo Electric Power Company (in english) detailing the modes and quantities of spent fuel stored at the Fukushima Daiichi plant where containment buildings #1 and #3 have exploded,” he wrote on March 14.

The Powerpoint is entitled Integrity Inspection of Dry Storage Casks and Spent Fuels at Fukushima Daiichi Nuclear Power Station and can be read in full here. The document adds a new and frightening dimension to the unfolding disaster.

The Fukushima Daiichi plant has seven pools dedicated to spent fuel rods. These are located at the top of six reactor buildings – or were until explosions and fires ravaged the plant. On the ground level there is a common pool in a separate building that was critical damaged by the tsunami. Each reactor building pool holds 3,450 fuel rod assemblies and the common pool holds 6,291 fuel rod assemblies. Each assembly holds sixty-three fuel rods. In short, the Fukushima Daiichi plant contains over 600,000 spent fuel rods – a massive amount of radiation that will soon be released into the atmosphere.

It should be obvious by now that the authorities in Japan are lying about the effort to contain the situation in order to mollify the public. It is highly likely there are no workers on the site attempting to contain the disaster.

Earlier today, a report was issued indicating that over 70% of these spent fuel rods are now damaged – in other words, they are emitting radiation or will soon. The disclosure reveals that authorities in Japan – who have consistently played down the danger and issued conflicting information – are guilty of criminal behavior and endangering the lives of countless people.

On Tuesday, it was finally admitted that meltdowns of the No. 1 and No. 2 reactor cores are responsible for the release of a massive amount of radiation.

After reporting that a fire at the No. 4 reactor was contained, the media is reporting this evening that it has resumed. The media predictably does not bother to point out why the fire is uncontainable – the fuel rods are no longer submerged in water and are exposed to the atmosphere and that is why they are burning and cannot be extinguished.

It cannot be stressed enough that the situation at Fukushima represents the greatest environmental disaster in the history of humanity, far more dangerous that Chernobyl, and the government of that country is responsible.

—

Perhaps the most underreported and deadliest aspect of the three explosions and numerous fires to hit the stricken Fukushima nuclear reactor since Saturday is the fact that highly radioactive spent fuel rods which are stored outside of the active nuclear rod containment facility are likely to have been massively compromised by the blasts, an elevation in the crisis that would represent “Chernobyl on steroids,” according to nuclear engineer Arnie Gundersen.

As you can see from the NPR graphic below, the spent fuel rods are stored outside of the active nuclear rod containment casing and close to the roof of the reactor complex. Video from Saturday’s explosion and subsequent images clearly indicate that the spent fuel rods at Fukushima unit number one could easily have been compromised by the blast.



According to Arnie Gundersen, a nuclear engineer at Fairewinds Associates and a member of the public oversight panel for the Vermont Yankee nuclear plant, which is identical to the Fukushima Daiichi unit 1, the failure to maintain pools of water that keep the 20 years worth of spent fuel rods cool could cause “catastrophic fires” and turn the crisis into “Chernobyl on steroids.”

The BBC is now reporting that “spent fuel rods in reactors five and six are also now believed to be heating up,” with a new fire at reactor 4, where more spent rods are stored, causing smoke to pour from the facility.

“Japanese news agency Kyodo reports that the storage pool in reactor four – where the spent fuel rods are kept – may be boiling. Tepco says readings are showing high levels of radiation in the building, so it is inaccessible,” adds the report.

“At the 40-year-old Fukushima Daiichi unit 1, where an explosion Saturday destroyed a building housing the reactor, the spent fuel pool, in accordance with General Electric’s design, is placed above the reactor. Tokyo Electric said it was trying to figure out how to maintain water levels in the pools, indicating that the normal safety systems there had failed, too. Failure to keep adequate water levels in a pool would lead to a catastrophic fire, said nuclear experts, some of whom think that unit 1’s pool may now be outside,” reports the Washington Post.

The rods must be kept cool because otherwise they start to burn and, in the case of reactor number 3, would release plutonium and uranium in the form of vapor into the atmosphere.

“That’s bad news, because plutonium scattered into the atmosphere is even more dangerous that the combustion products of rods without plutonium,” writes Kirk James Murphy.

“We’d be lucky if we only had to worry about the spent fuel rods from a single holding pool. We’re not that lucky. The Fukushima Daiichi plant has seven pools for spent fuel rods. Six of these are (or were) located at the top of six reactor buildings. One “common pool” is at ground level in a separate building. Each “reactor top” pool holds 3450 fuel rod assemblies. The common pool holds 6291 fuel rod assemblies. [The common pool has windows on one wall which were almost certainly destroyed by the tsunami.] Each assembly holds sixty-three fuel rods. This means the Fukushima Daiichi plant may contain over 600,000 spent fuel rods.”

There have been massive design issues with the Mark 1 nuclear reactor stretching back three decades.

As ABC News reports today, “Thirty-five years ago, Dale G. Bridenbaugh and two of his colleagues at General Electric resigned from their jobs after becoming increasingly convinced that the nuclear reactor design they were reviewing — the Mark 1 — was so flawed it could lead to a devastating accident.”


“The problems we identified in 1975 were that, in doing the design of the containment, they did not take into account the dynamic loads that could be experienced with a loss of coolant,” Bridenbaugh told ABC News in an interview. “The impact loads the containment would receive by this very rapid release of energy could tear the containment apart and create an uncontrolled release.”


www.Roshaz.com

 

[BigInch]

I would imagine that it would tend to change for the worse rather than the better. "We've got a problem. Let's tell the truth for a change.", isn't usually a course of action that all of a sudden happens to fall into the set of more readily generated alternatives of those that don't already have a long, hard and fast policy of honesty and integrity.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[zdas04]

Jonhors,
Any piece of writing with the phrase:

... a hellish repository where a staggering number of spent fuel rods...

and

Perhaps the most underreported and deadliest aspect of the three explosions and numerous fires to hit the stricken Fukushima nuclear reactor since Saturday is the fact that highly radioactive spent fuel rods which are stored outside of the active nuclear rod containment facility are likely to have been massively compromised by the blasts, an elevation in the crisis that would represent "Chernobyl on steroids," according to nuclear engineer Arnie Gundersen.

can ever be taken as objective. (He repeated the "Chernobyl on steroids" quote a couple of times, it is just too incendiary to let lie.) The author of that story had an agenda that did not include informing anyone. The article is so full of half truths, spin, and misleading information that you have to wonder what his actual agenda was.

In contrast, the outstanding links to MIT that pmover included above have facts instead of hyperbole.

In that article, they explain that one of the reactors was down for refueling and the old core was placed in the spent fuel pond. Since this fuel was recently in service, it has a lot of short-lived decay products and is generating a lot of heat. The helicopters are dropping the water in this pond to keep the level from lowering too much. It doesn't look like they are really dropping water on the reactors (which are inside a massive concrete and steel secondary containment, which has not been breached). The buildings that were damaged and destroyed by the explosions were not part of the containment strategy.

David

 

[VEBill]

"The Fukushima Daiichi plant has seven pools dedicated to spent fuel rods. These are located at the top of six reactor buildings – or were until explosions and fires ravaged the plant."

Is that true?

How does that relate to the building damage caused by the hydrogen explosions?

 

[CajunCenturion]

My apologies for the novice questions.

Based on all the things I've read so far, it seems that the reactors are contained within a primary structure, which itself is within a secondary containment structure. All of this was inside the outer building shell.

Even with outer shell building gone, the reactor is still inside the primary containment structure which is still inside the secondary containment structure.

Question: If water is being dropped from a helicopter on an affected reactor, then what is the water actually coming in contact with? Isn't the secondary containment structure is still on the outside? How effective can that be in the cooling process? If the secondary containment structure is breached, then is the water being sprayed onto the primary containment structure? Again, unless the primary containment has also been breached, how does spraying the outside of the primary containment aid the cooling of the reactor?

Good Luck
--------------
As a circle of light increases so does the circumference of darkness around it. - Albert Einstein

 

[VEBill]

Diagram of building here:

http://www.theregister.co.uk/2011/03/17/fukushima_thursday/