Nuclear Plant Design

The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in the Ukrainian SSR (now Ukraine). It is considered the worst nuclear power plant accident in history, and it is the only one classified as a level 7 event on the International Nuclear Event Scale.

The disaster began during a systems test on 26 April 1986 at reactor number four of the Chernobyl plant, which is near the town of Pripyat. There was a sudden power output surge, and when an emergency shutdown was attempted, a more extreme spike in power output occurred, which led to a reactor vessel rupture and a series of explosions. This event exposed the graphite moderator components of the reactor to air, causing them to ignite. The resulting fire sent a plume of radioactive fallout into the atmosphere and over an extensive geographical area, including Pripyat. The plume drifted over large parts of the western Soviet Union, Eastern Europe, Western Europe, and Northern Europe. Large areas in Ukraine, Belarus, and Russia had to be evacuated, and over 336,000 people were resettled. According to official post-Soviet data,^[1][2] about 60% of the fallout landed in Belarus.

The accident raised concerns about the safety of the Soviet nuclear power industry, as well as nuclear power in general, slowing its expansion for a number of years and forcing the Soviet government to become less secretive about its procedures.^{[3][notes 1]}

Russia, Ukraine, and Belarus have been burdened with the continuing and substantial decontamination and health care costs of the Chernobyl accident. Fifty deaths, all among the reactor staff and emergency workers, are directly attributed to the accident. Estimates of the total number of deaths attributable to the accident vary enormously. Despite the accident, Ukraine continued to operate the remaining reactors at Chernobyl for many years. The last reactor at the site was closed down in 2000, 14 years after the accident.^[4]

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

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What's your point, here?

The Chernobyl incident had nothing to do with the plant's susceptibility to seismic events. It was human error.

The disaster began during a systems test . . . which led to a reactor vessel rupture

By my understanding, you have some facts wrong. For the test, some safety systems were bypassed/disabled. Also, it had no containment vessel to rupture.

If you follow the link given in the post, you'll see that the content is copied verbatim from Wikipedia, so the author(s) of the wiki are the people to disagree with.

"Economics" Exact answer.

But human life is a valuable one so why can't we put this Economics in dust bin.

Because it would bankrupt economies.

In the history of mankind, what has caused more deaths: poverty and economic troubles or under engineered designs (that don't cover any possible worldwide disaster)?

FYI the nuclear plant in Japan was earthquake proofed, it was the tsunami that flooded out the generators and electrical systems that caused the problems. It is a good example that you can design for a specific large catastrophic event and even some secondary cosndierations, and still not envision all the secondary catastrophes that could occur that cause problems. It is a good example of what happens if a nuclear plant loses all power.

It also demonstrate how management responds to an emergency. The management tried to recover the facilities, cost effectively protecting the companies investment by trying to induce minimal damage to the reactors from shut down. They were reacting to the increasing risk rather than being proactive and flooding the reactors wiith borate to start with. Then they were also not fully disclosing the situation to the government of Japan. Does this kind of mismanagement during an emergency sound familiar? Think BP.

If you're referring to the reactors in Japan, we need to remember, it wasn't the earthquake that directly damaged the reactors, nor was it the tsunami directly. The power got knocked out, and water flooded the emergency generators that would have been used to circulate cooling water.

I think they've pretty well got reactors earthquake resistant. I'm sure this incident will bring about a lively discussion and a lot of work toward making reactors impervious to flooding in areas where that might be a possibility.

"There is not a single medicine that cures all diseases"

Design consideration mitigates what are the critical conditions on the location for a safe operation, plus of course the economic side, "feasibility".

This post was deleted because it did not adhere to the behavioral policies of the site. Please review Section 14 of the CR4 Site FAQ and the CR4 Rules of Conduct.

Self moderation?

No. I noted that the thread's title was "recycled" from a recent thread, and that the main question wasn't very bright.

But you must remember that kastrupsky and joe.fordham insulted people repeatedly without any Administrative intervention for a long time. There seems to be some kind of double standard, as others have noticed, too.

For once, it wasn't either one of us.

It might surprise some of the readers here, we have at least two nuclear plants built near fault lines. One is San Onefre Sta. near the San Andreas fault and the other is Vermont Yankee Sta. Green Mountain Power. Neither of them are located on the coast. Of course they are located near water and hopefully the effect of an earthquake on the river? has been taken into consideration.

As far as the coastal units go, I don't remember any design considerations that would address a twenty five foot high speed wave, the most basic analysis would show that backup power in the form of a locally located internal combustion engine would in all probability be doomed to failure.

Here on the east coast of the US we typically think in terms of the occasional hurricane that results in flooding the basements. This in itself is more than a nuisance and a lot more predictable than a earthquake. I can almost guarantee you that a twenty five foot wave sweeping inland six miles would take out the majority of the electrical systems in it's path, and would cause most of the internal combustion engines that don't float to ingest water instead of air.

So if we are going to protect the backup power we either need to move the source inland and up, or make it so that it can float or make it submersible.

Do we need to make the pumps, valves controls etc in the containment submersible?

Do we need to have reserve coolant tanks pressurized with a gas to 1.5 times max. expected pressures and a volume of 300 to 400 % normal flooded vessel condition?

Do we need to design the structures to withstand an eleven on the Richter scale?

Can we afford to do these things? Can we not afford to do these things?

sounds like a good plan to reuse old ship hulls.. (ie aircraft carriers and old subs)

keep them afloat and tether them offshore, and put reactors in them.

then if they go for a meltdown.. they just sink... end of problem.. mostly
at least the water limits the amount of contamination to the eco system.

chris

Doesn't it then limit the contamination to the water it floats in and any downsteream water systems, adn the ecosystems in those water systems, plus any other systems that consume from those ecosystems residing in any of that water? I am guessing seafood would not be as healthy as they now consider it.

this depends on the type of problem. If it is a total meltdown, it is going to be catastrophic no matter what. The consequences are actually the least in an oceanic environment, due to the cooling factor, and the fact that water stops radiation in just a few feet. If it is a cooling valve or pump failure, there are a lot more options when cooling water is just a few feet away.

What is weird about the Japan problem is that they had a break in the electricity somehow.. and then they lost cooling capacity... all when nuclear plants are designed to produce electricity. What gives?? Perhaps Nuclear plants should be designed to supply their own electricity first, before putting out to the grid...

Chris

This seems limited to the thermal reaction, but what of the chemical reactions and dissolution into the seawater? How much Uranium would dissolve into the seawater and be advected/diffused through out the system. Is the risk of spreading contaminated materials through the larger water system more rapidly balanced against the thermal melt down and encapsulation in the soils (of course if they release radioactive materials into the atmosphere, then you have a wroldwide contamination). Plus I am not so confident that a floating platform on the ocean is a more stable foundation for a facility, especially if we look at 1000 year risk factors on land. what would a floating platform look like if it was designed to resist waves that occur at or above a 1000 year recurrence (accounting for the current understanding that ship designer have been underestimating wave height in relation to recurrence probabilities forever)? Marine engineering is far less accurate than land based engineering regarding such issues.

Firstly, everything goes to the sea. If we build nuclear on land, and an event were to occur, it would find its way into the oceans and lakes. Throughout the history of the earth, the long running geological and hydrological cycles have the ocean as the primary base, in my opinion.

Secondly, we are surrounded by background radiation, and we are bathed in radiation from the sun (largely shielded by the Van Allen belts of course) but earth has had measurable variations in atmospheric (and subsequently oceanic) radiation at times.

The earth takes care of itself, and on occasion unimaginable events occur that wipe out entire populations of indiginous life forms. (not just human) This is the backdrop for our small scale short lives, and the relatively small energies we can release at any accidental event. The earth will find a way to absorb that energy.. but of course, there will be an impact to life on earth, proportional to the energy release, and its relative contamination.

The surface of the ocean would appear to be a very chaotic environment upon which to base a dangerous technology. I agree that it is an engineering challenge, but I would not agree that it is insurmountable, with adequate resources and commitment.

In the world of large stakes energy projects, it is essentially a war between the economics of the project, and the engineering redundancy requirements (in the case of nuclear especially) of the project. This understanding is fundamental to the safety and lifespan of the project. I know you all know this.. I'm just stipulating it to clarify that it isn't about engineers not knowing how to build a safe plant.

It is about being able to design and build a safe plant with the money that is given. Certain trade-offs have to be made. The sky is not the limit... the money is.

Call me naive, but I believe that a safe nuclear system can be specified, designed, and implemented... safe for a hundred years or a half-life. but who is going to pay for the first one? This is why we have failures. This is why contamation is even a question.

Chris

In my humble opinion, the proper approach to the nuclear energy conundrum is smaller, distributed systems, like the Toshiba S4 or the Hyperion design. Inherently safer, and, having smaller units distributed over larger areas would decrease the potential for a single major catastrophe as is currently under way in Japan...

There are systems in these plants which initiate automatic shutdown based on input from seismic sensors^[1], so this one could not supply its own power. Additionally, the power grid in the area got wiped out (partly because the other nuclear sites in the region shut down for the same reason).

The big mistake here seems to have been not ensuring an independent power supply for the cooling system capable of withstanding the conditions which arose.

[1] I've read this more than once, but can't cite a reference (and I'm too tired to go looking for one).

Before thinking in terms of moored ships for emergency recovery, one should a take a long, hard look at what happened to the ships that were caught in the tsunami...

As others have pointed out, it was neither the earthquake nor the tsunami that resulted in the current situation- it was the loss of backup power. The designs of the plants definitely withstood the "1000 year" test.

Actually all the nuclear power plants in California are built "near" fault lines. You can not build anything within California withing 50 miles of the coast without building near (within 5 miles of) a fault line, at least not South of Santa Rosa (so southern 2/3 of State). The Loma Prieta Quake that did so much damage to San Francisco was nearly 75 miles from SF and did not lie on the San Andreas fault, nor was the Northridge Quake.

"Why the world hasn't set any ultimate Richter value that every nuclear plant has to design"

There is no world nuclear authority. Each country sets their own standards. There are "international organizations" that monitor nuclear activity, but they have no true authority to dictate plant designs.

http://www.iaea.org/

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

The first link is so clogged with traffic, it won't open. Your right, I don't think they can dictate anything.

The IAEA facebook page is up and running. And yes, they can only advise.

Apparently the design of these particular nuclear reactors was criticized a long time ago for high risk of meltdown in case of a failure, but the industry assurance won over and so there are a number of this type still in operation.

http://www.nytimes.com/2011/03/16/world/asia/16contain.html

I go along with JohnDG, GA, ( Economics, Simple as that.) there are a number of possibilities as to why the back up systems did not work, the first thing that come to mind is that equipment was not isolated from a tsunami, motors, pumps, generators, distribution boxes etc, these items should be in an isolated room, and alternative emergency supplies lines underground, but that costs money? This is of cause assuming that the earth quake did not damage the system to the point that it could not work, fracturing the circulation system and associated equipment.

Regards JD.

As is easy to see with a cursory glance at recent history, we've had a lot more problems with nuclear energy than most of its advocates said we should expect. That these incidents tend to each be due to unique factors underscores for me the need for better reliability and safety engineering for all plants.

Maybe there isn't a global standard. Maybe there needs to be. I think nuclear plants around the world might need to answer the charge that they are under-engineered. (Take your concerns for profit elsewhere. They have nothing to do with safety and reliability.)

Energy production and distribution of any form carries risks and creates pollution. Nuclear may well be getting the raw deal in terms of public opinion, because acid rain, mountain top removal, massive oil spills, natural gas plumes, heavy metal waste and flooded antiquities all suck.

You make some good points but I've heard similar comments to this line (from other people too) and it just doesn't sit well with me.

"Take your concerns for profit elsewhere."

I don't know if you can convince any company to operate without a profit. You wouldn't pay your boss to work for him would you?

I heard something interesting on a news video, the subject of the interview was a disgruntled GE engineer that had some disagreement with the design of the BWR reactor and had in fact quit the company over the issue.

I wasn't able to discern if his issue was with the Mark 1 or some other design, The interesting point of the discussion was that he referred to the fire in the spent fuel pool of reactor #4. He stated that the #4 unit was in an overhaul status at the time of the event and some of the active fuel had been moved to the spent fuel pool. Of course this makes the fire a much more important concern than if the fuel was in fact spent.

The design question that comes up with this scenario is. Do we need to build a secondary containment area for the times the unit is being overhauled. I am speaking to the older designs. Newer designs affect this by handling spent fuel underground, a form of a secondary containment.

It still leaves the question can you leave an open reactor vessel or spent fuel pool without a fully intact containment area around it.

As these design problems keep stacking up it makes you think in terms of what are we speaking of in relative terms, If we were to compare this with an automobile, these units were built about 15 years after the technology was developed commercially. This would be about like having a 1930 Ford and trying to update it to todays emission and safety standards. Not practical or economical.

This event will definitely bring about some changes to how we do things going forward.

At this point I think all we can do is offer up a prayer for the brave souls that are facing this problem and hope their sacrifice is appreciated.

? 1930 Ford. Are you equating the technology used in these Japanese nuclear facilities to a 1930s Ford, and updating them to current technology would be equivalent to updating that Ford to current emmission standards? That would equate the date as you indicated that the nuclear technology was commercial availble with 1930s. However, that assumes the rate of technological advancement has been as rapid as that in Cars. Even though production and competitive advancements in the automobiles industry has been relatively highly favored throughout their history, and nuclear technology advancements have been hamstrung due to perception (and as it turns out sometime real) of threats to humanity. I would even suspect you could Take a 1930 atomic physicist (who at the time they had not seen a working nucler power plant, so a nuclear engineer would not exist) and drop him in a nuclear power plant and he could comprehend the entire process and mechanics by which it operates, I suspect you would have a hell of a time doing the same with a automotive mechanical engineer that really designed 1930s ford cars with modern cars.