Nuclear Catastrophie

[NS_Rider]

Ya'll keep your "spent nuclear waste" off the East Coast...LOL... We already have enough of our own. There is a Nuclear Plant in Point Lepreau, New Brunswick. And it is very close to the ocean. http://poweringthefuture.nbpower.com/en/Default.aspx
I have been following this thread off and on, and appreciate all the information that has been shared. We currently have a International Student with us from Osaka, Japan. She is forunate, that her family is safe. Thanks for sharing the wealth of knowledge.

[SPARKY]

I agree, I have been telling my neighbors about this thread.  This interaction has been the most informative, very factually presented by people in different industries or professional backgrounds, from a slightly different bias. This is the way the deductive learing process  WORKS!!  now if I just don't have to much of an AGE bias CRS     

[Seldom Seen Slim]

We're resting on the Laurentian Shield here n the UP of Michigan (and neighboring states).  The rock is stable and hard - to the point that the Navy used this area to build their submarine communications antenna and system -- Project Elf. 

This part of the US is also pockmarked by hundreds, if not thousands, of deep holes dug for mining copper and iron.  Up in Hoton, where Walt is going to school, the deep ones were on the order of 7,000 below surface - and since they were angled -- more than 9,000 feet of overall length. 

Those two factors would make it, at least at first blush, a great place for storage -- pre-dug holes and very stable geology.

I wonder why the UP hasn't been talked about as a long term repository for nuclear waste?  Could it have anything to do with the proximity of the Great Lakes?

[Tman]

From what I have gathered searching a weeks worth of news is that the Tsunami wiped out the emergency generators for backup AFTER the earthquake/tsunami took out the basic infrastructure. No pwoer, now cool water for the fuel rods. That led to overheating, explosions and leaks. There is also some speculation that the Japanese has "double stacked" spent fuel rods in one of the storage ponds making it easier to overheat when things hit the fan.

Okay... here I am for the present in Quebec, Canada. The only English language programming on the radio is our venerable CBC.... so, the hysteria monger here in Canada are attempting to use  the Japanese situation as wa y to "force" the governments to back down on the coninued or expanded use of nuclear power.

The interesting thing is tha all of the nuclear power facilitie in Canada are nowhere near any oceans.... the Great Lakes don't quite qualify as oceans, do they?

The big question tha has been bothering me and, to date, the radio pundits have not even discussed, is this: Did the reactors suffer the damage from the earthquake directly, or did they actually survive it only to have their emergency infrastructure wiped out by the tsunami?..... in essence, was the earthquake directly the cause of the catastrophe or was the resulting tsunami the cause?

Because, if the reactors can survive the earthquake...... in an area like central Canada which is not noted for large magnitude earthquakes, and having virtually no possibility of resultant tsunamis even with a large earthquake .... are the fear mongers really nothing more than that?

[hotrod]

Correct the reactors that were in operation immediately did an emergency shutdown (scram) when the earth quake occurred. This shuts down the power production of the nuclear reactor, by inserting the control rods to shut down the chain reaction. This still leaves the decay heat of the nuclear fuel that had just fissioned shortly prior to the shut down. This decay heat starts out at some where near 7% of the power level the reactors were at when the SCRAM occurred,so we are talking about 6-7 mega watts of heat that needed to be dissipated.

The reactor facilities successfully survived the mechanical effects of the earth quake even though the earthquakes were more intense than the design quake they were built to survive (this means they were well engineered for earth quake shaking). Design quake was about a 7.2 if I remember correctly, the actual quake has now been calculated to be a 9.0 This means the actual energy released was on the order of 500 x the energy designed for.

http://en.wikipedia.org/wiki/Moment_magnitude_scale

http://earthquake.usgs.gov/learn/topics/how_much_bigger.php
http://earthquake.usgs.gov/learn/topics/calculator.php

http://www.world-nuclear.org/info/inf18.html

Due to the decay heat, the reactors need to be actively cooled for some time after shut down, normally it takes something like 4-5 days to cool the core to the point it is considered a "cold shutdown", meaning the decay heat is low enough that no forced cooling is needed.

To accomplish the cooling, they had emergency diesel generators to power cooling pumps that kicked on immediately after the earth quake and reactor shutdown and these ran for about an hour cooling the reactor cores when the tsunami hit. The plant had protections for a tsunami event but the design height they were built for was about a 6.3-6.5 meter tsunami (I have seen both figures). The actual tsunami that struck the plant was about a 10 meter wave ( 32 -33 ft). This swamped the running diesel generators and took out external power line feeds to the plant, and destroyed all land access routes to the plants.

With the diesel generators swamped, they switched over to a third layer of emergency backup in the form of stand by batteries that could power some cooling pumps and equipment. These batteries were only good for hours (not sure of the exact duration of emergency battery power), before they were exhausted.

That is when things started to get out of hand. With outside access and power essentially destroyed, it was impossible to bring in additional backup equipment and power fast enough to prevent some over heating and that resulted in the emergency steam releases where they tried to release excess steam pressure in the reactor pressure vessel to protect it from over pressure. When they released steam it contained hydrogen gas which when mixed with air became an explosive fuel air mixture and exploded when it found an ignition source, blowing the exterior weather sheathing walls off the super structure of the upper part of the buildings. Although the explosions were violent and impressive, because the walls were of light construction they acted as blow out panels and most of the energy went up and away from the plant structure, and did not appear to harm the physical high strength containment structure that separates the reactor from the outside world.

Later one of the cooling torus structures in one of the reactors apparently was damaged by an internal hydrogen explosion or some other event. They only know that they heard "loud noises" and that pressure in the torus rapidly dropped to atmospheric pressure.

In short the nuclear reactors successfully survived not 1 but at least 4 insults that were above design limits, (earth quake largest ever recorded in Japan and 5 th largest in modern quake history, a tsunami about 1.5X larger than the design tsunami, and an extended period with no forced cooling due to the swamping of the emergency generators, exhaustion of the emergency battery backups and an in ability to resupply and repair due to the destroyed surrounding area blocking access, followed by fuel air explosions due to hydrogen mixed with steam vented to protect the pressure containment structures).

From an engineering view point the plants did very very well considering all these insults. Whether there were easily foreseeable protective measures that could have been included in the design to cover even these issues (such as elevated locations for the diesel generators, higher tsunami protection etc.) will all come out in time.


I am sure planning for tsunami protection of nuclear power plants near the sea will change construction practices world wide as a result of this event.
Keep in mind that these are 30 year old plant designs and some of the newer plant designs have much more robust cooling systems that are less reliant on external forced cooling in emergency shut down mode.

All things considered I think the plants did very well given what got thrown at them.

Larry

[fastman614]

Hey hotrod larry,
That is a pretty interesting post.... and pretty much the answer to what I was asking.... It was my gut feeling that the sequence that you describe was how it all came to be....

It is remarkeable though that, here in Central Canada, nobody has presented it this way.... but my earlier post in which I stated that newsroom editors strain the wheat from the chaff and then go ahead and print the chaff is probably too close to the truth.... if the facts of the matter were widely published, the fear mongers would be rather deflated and then what controversy would the editors have ongoing chaff with which to fill newspapers?...

It is sort of shameful when these issues and know the facts surrounding them are pretty much life or death issues.... from one had- NOT knowing the true potential dangers of radioactive exposure is a potential death dealing issue.... and the potential for death dealing stress from being unduly worried about non-existent problems which get fomented due to fear mongering and the more or less deliberate barrage of mis-information is, on the other hand, an equal problem....

Gee, I never knew that we had people with this level of knowledge amongst the Land Speed racing community!.... keep it up, guys!

[fastman614]

Ya'll keep your "spent nuclear waste" off the East Coast...LOL... We already have enough of our own. There is a Nuclear Plant in Point Lepreau, New Brunswick. And it is very close to the ocean. http://poweringthefuture.nbpower.com/en/Default.aspx
I have been following this thread off and on, and appreciate all the information that has been shared. We currently have a International Student with us from Osaka, Japan. She is forunate, that her family is safe. Thanks for sharing the wealth of knowledge.

NS Rider.... An interesting post and thanx for the link....

Now, another quetion.... a 10 meter high tsunami could travel uphill to what elevation above sea level prior to its energy being spent.... the Point LePreau plant really does not look to be that high above sea level....

[Geo]

A measurement of earthquakes I did not know about quantifying ground movement in horizontal and vertical planes, measured in Galileo units - Gal (cm/sec2) or g - the force of gravity, one g being 980 Gal. This is a build spec used for new nuclear facilities.

Also with historical reports of past earthquakes and nuclear power plant events up to this past week.

http://www.world-nuclear.org/info/inf18.html


I read about the size of the electric motors for the pumps but cannot find it again.  1000 hp is the number I recall which would take a very large generator.


Nuclear Power Plants & Earthquake Activity

http://googlemapsmania.blogspot.com/2011/03/nuclear-power-plants-earthquake.html

Geo

[wobblywalrus]

In the old days of coastal engineering when many of these plants were designed we relied a lot on simplistic conservative design assumptions, elementary computer modeling (by today's standards), experience at the sites, and we included big safety factors.  There is no way I can know what went into the Point Le Preau hydraulic design, but I'll bet it is robust.  Most of us hydraulic engineers know that wave height prediction is a very inexact science and our motto is "when in doubt, build it stout."

[panic]

I wonder why the UP hasn't been talked about as a long term repository for nuclear waste?

The wrong people own the property.

[Seldom Seen Slim]

You mean the good ol' federal government, don't you?  As for private parties -- well, we own 60 acres and nobody's asked us for permission.

[Dean Los Angeles]

I am sure there was damage from the earthquake. This 40 year old facility was designed with an antiquated knowledge of earthquake dynamics. I'm sure there were seismic upgrades through the years, but it's much harder to upgrade, and cost often trumps necessity.

All large projects suffer from delayed preventive maintenance. Any time you want to save money, yank it from maintenance. TEPCO has a past history of falsifying records and skipping inspections.

The before and after pictures show a lot of tsunami damage to the facilities between the main building and the ocean. That could have been vital equipment.

All of that happened in the first hour. I believe that everything that has happened past that point is largely influenced by human failures.

It didn't take too long to realize that significant damage to the mechanical and electrical structure was caused by the tsunami. Work should have begun at that point to pump the water out and start repairing water related damage. By Saturday morning I would have had spare pumps coming my way.

In another setback, the plant's operator said Monday it had just discovered that some of the cooling system's key pumps at the complex's troubled Unit 2 are no longer functional — meaning replacements have to be brought in. Tokyo Electric Power Co. said it had placed emergency orders for new pumps, but how long it would take for them to arrive was unclear.

It took them 10 days to figure out that earthquake damaged, tsunami flooded, seawater choked pumps wouldn't work? They couldn't yank a pump from a facility that is under maintenance? The pumps from the shut down unit #4 wouldn't work?

Shortly after the batteries died and all power went away, the water temperature reached the boiling point. Pressure exceeded design limits. Three hours after the earthquake the first steam was released. Now the workers risk goes way up because that steam is mostly carried away, but some comes back down on the plant.

The steam internally is used to run a pump that circulates the water inside to cool things off, but at some point all the water is overheated. The heat has no place to go so temperatures continue to rise. Venting steam helps, but more water has to be added. At some point they start running out of clean water to inject.

Batteries from other nuclear plants were sent to the site and mobile generators arrived within 13 hours, but work to connect portable generating equipment to power water pumps was still continuing as of 15:04 on 12 March. Generators would normally be connected through switching equipment in a basement area of the buildings, but this basement area had been flooded. After subsequent efforts to bring water to the plant, plans shifted to a strategy of building a new power line and re-starting the pumps

Plans shifted? Really? Wouldn't you bring in enough people to work as many strategies as you could, only stopping when something else actually worked?

As the reactor heated past 2,200 degrees early last Saturday, hydrogen started building up. This is a well known and documented problem. This happens when the water level drops below the radioactive rods and there is nothing to cool them.

TEPCO knew that they had run out of water and the rods were exposed. Caesium-137 and iodine-131 were detected and that could only happen through uncovered degrading rods. I can't fathom why, but the hydrogen gas was vented into the containment building. It should have been harmlessly routed to a flare stack to burn off, but that may not have been possible without power.

25 hours after the earthquake there was a massive explosion of hydrogen gas. 8 hours earlier there were indications that the rods were uncovered. 5 hours after the explosion the decision was made to start injecting sea water.

There is speculation that the Japanese culture had a lot to do with decision making. The desire to save face, and profits led them to delay far, far too long on the decision to inject sea water. That decision means that a multi-billion dollar investment is toast.

Also the pool that was being used as a seawater source for the pumps ran dry and caused the fuel to be exposed. The pump ran out of fuel again causing the fuel to be exposed.

While all of this is going on nobody thought to check the spent fuel pool in unit #4? There have been reports that the spent fuel pool on unit #2 may have been a problem early on, the spent fuel pool on unit #3 definitely was a problem.

There has been a lot of heroic mention of the "Fukushima 50" fighting to save the plant. At one point it was the "Fukushima Zero" when everyone was pulled out due to high radiation levels. Several analysts have mentioned that due to the danger to tens of thousands of people around the plant that suicide missions shouldn't be ruled out. They should have bought in enough people working in short shifts to keep the required number of people working the many, many problems.

There have been reports that power will be supplied to units 3 and 4 soon. Have you noticed the tons of water they are still pouring into that building? If you stop pouring water the radiation levels soar. If you don't stop you can't fix the electrical. Both units have massive damage from the explosions.

There have been mentions of entombing some portion in concrete. There are serious problems with that approach. If the reactor vessel is entombed the heat has no place to go. It could cause the original concrete containment structure to crack, along with the new.

The spent fuel pool is a bigger problem. You can't put concrete where there is high heat, it crumbles to sand. You can't put much weight on the pool because it is hanging off the side of the reactor structure and the whole thing might collapse. That means you have to put a structure underneath to support it.

These boys have many months of work before they have a handle on this problem.

[Tman]

Geez Dean, don't paint such a rosey picture now will ya!?

[fastman614]

WOW!

[Dean Los Angeles]

Well the cracks have started. Not in the reactor, in the history of this plant and the Japanese nuclear industry.

The Japan Nuclear Energy Safety Organization, a mostly government-funded group monitoring safety and conducting inspections, reported Daiichi had the highest accident rate of any big Japanese nuclear plant. The data shows Daiichi's workers were exposed to more radiation than their peers at most other plants

Tokyo Electric missed 117 inspections at Kashiwazaki, the nuclear safety agency late last year ordered the utility to conduct a companywide review of its inspection systems. In response, Tokyo Electric reported that it skipped 54 separate inspections, the 33 at Fukushima Dai-ichi — whose Unit 1 is one of Japan's oldest reactors in operation — and the rest at the nearby Fukushima Daini.

Just a month before a powerful earthquake and tsunami crippled the Fukushima Daiichi plant at the centre of Japan's nuclear crisis, government regulators approved a 10-year extension for the oldest of the six reactors at the power station despite warnings about its safety.

The committee reviewing extensions pointed to stress cracks in the backup diesel-powered engines at Reactor No. 1 at the Daiichi plant, according to a summary of its deliberations that was posted on the Web site of Japan's nuclear regulatory agency after each meeting. The cracks made the engines vulnerable to corrosion from seawater and rainwater.

Tokyo Electric had met all required protections from earthquakes. Inspectors, however, had spent just three days inspecting the No. 1 unit, a period that industry experts say was far too brief because assessing the earthquake risk to a nuclear plant is one of the most complex engineering problems in the world. It did, however issue caveats that the operator TEPCO to monitor potential damage from radiation to the reactor’s pressure vessel, which holds fuel rods; corrosion of the spray heads used to douse the suppression chamber; corrosion of key bolts at the reactor; and conduction problems in a gauge that measures the flow of water into the reactor

In 2000, a whistle-blower at a separate company that was contracted to inspect the reactors told regulators about cracks in the stainless steel shrouds that cover reactor cores at Fukushima's Daiichi plant. But regulators simply told the company to look into the issue, allowing the reactors to keep operating.

Nuclear regulators effectively sat on the information about the cracks in the shrouds, said Eisaku Sato, the governor of Fukushima Prefecture at the time and an opponent of nuclear power. He said the prefecture itself and the communities hosting the nuclear plants did not learn about the cracks until regulators publicized them in 2002, more than two years after the whistle-blower reported the cracks.

In 2003, regulators forced Tokyo Electric to suspend operations at its 10 reactors at two plants in Fukushima and 7 reactors in Niigata Prefecture after whistle-blowers gave information to Fukushima Prefecture showing that the company had falsified inspection records and hid flaws over 16 years to save on repair costs. In the most serious incident, Tokyo Electric hid the large cracks in the shrouds.

Eighteen months before Japan's radiation crisis, U.S. diplomats had lambasted the safety chief of the world's atomic watchdog for incompetence, especially when it came to the nuclear power industry in his homeland, Japan.

An unnamed IAEA official told the G8 Nuclear Safety and Security Group in December 2008 that guidelines for seismic safety had been revised only three times in the past 35 years and the IAEA was re-examining them, another cable showed.

"Also, the presenter noted recent earthquakes in some cases have exceeded the design basis for some nuclear plants, and that this a serious problem that is now driving seismic safety work."

Tepco's 17 nuclear reactors were temporarily shut down after it admitted in 2002 that it had falsified inspection findings and covered up serious flaws for 16 years. The company's president and four other executives resigned after the news became public.

In 2004, Kansai Electric's officials at the Mihama plant admitted they had not acted on safety warnings before a corroded pipe burst, spewing superheated steam that killed four workers. (The steam was not radioactive.)

It wasn't until 2007 that Hokuriku Electric Power Co. revealed that its Shika nuclear plant had a critical accident in 1999.