Merged nuclear power safe?

[DC]

Yes, I did.



Here is Dr. Hardings linkedin profile.

Your turn. Put up or shut up.

EDIT: I've also linked previously the qualifications of several of my other contacts at the CNS:

and what does he say what happens if the vessel brakes? i am pretty sure he does not claim it is impossible to happen.

 

[Sword_Of_Truth]

and what does he say what happens if the vessel brakes? i am pretty sure he does not claim it is impossible to happen.

List the qualifications of your experts please.

I gave you what you asked for even though I asked first.

 

[DC]

List the qualifications of your experts please.

I gave you what you asked for even though I asked first.

it was a comment by Wolfgang Renneberg, former boss of the german ministry for reactorsecurity.

So what does your expert say about a broken vessel?

 

[BobTheDonkey]

it was a comment by Wolfgang Renneberg, former boss of the german ministry for reactorsecurity.

So what does your expert say about a broken vessel?

Source?


And a couple pertinent bits from the above quote:

At Fukushima there is no carbon, nothing to burn, such a scenario is not possible here. The Fukushima reactor underwent a controlled shutdown and maintains the capability to be controlled and cooled.
...
Fukushima and Three Mile Island. TMI-I was a pressurized water reactor (PWR) supplied by Babcock and Wilcox. Due to operator error and poor design the reactor was driven into a state where the core was unintentionally exposed. Without cooling the tops of the fuel assemblies warped and some ruptured. While this was fatal to the use of that facility (and expensive to the shareholders) very little radioactive material was released into the environment. This is very similar to what would happen at Fukushima if the core were to be exposed.
...
If the core can be kept covered then the fuel rods will not rupture and there will be minimal environmental impact.

 

[DC]

Source?

when the vessel brakes do to the molten rods, not only will the cooling water be contaminated, but also the enviroment surounding the area.

 

[Christian Klippel]

it was a comment by Wolfgang Renneberg, former boss of the german ministry for reactorsecurity.

So what does your expert say about a broken vessel?

Renneberg? Really? That guy from "Renneberg Consult" who seems unable to afford a company eMail address, and instead uses @netcologne.de (a regular internet provider)? The Renneberg that seems to have fun taking part in the nuclear hysteria? The guy who favours and supports that political party that is most vehemently against nuclear energy?

I'm sorry, but that guy has a very big conflict of interest here. Oh boy, that won't end well, i think.

Greetings,

Chris

Edit: Not to mention that his company creates studies/reports exlusively for the ant nuclear lobby organizations and said party ("Die Grünen").

Here is his company website. This guy is absolutely not neutral.

 

[BobTheDonkey]

when the vessel brakes do to the molten rods, not only will the cooling water be contaminated, but also the enviroment surounding the area.

Like the vessel broke at TMI:I?


ETA: As an aside and a part-time grammar nazi (and just generally because I think the translator is failing you on this one), the correct word is "breaks", not "brakes". This one really chaps my ass because I see the opposite mix-up on my car forum all the time. I hope you don't take this minor correction personally, it's not intended to be

 

[gumboot]

when the vessel brakes do to the molten rods, not only will the cooling water be contaminated, but also the enviroment surounding the area.

My understanding is there's a catchment area under the reactor so that even if the containment vessel is ruptured, the radioactive material will not go into the ground. Can anyone confirm that?

 

[DC]

My understanding is there's a catchment area under the reactor so that even if the containment vessel is ruptured, the radioactive material will not go into the ground. Can anyone confirm that?

yes i heard that too.

 

[Skwinty]

Here is a picture.

 

[Last of the Fraggles]

Regardless of actual damage done by the reactors, the psychological damage is done.

If people are walking away from this thinking nuclear power is unsafe then I think the damage was already done before this event. I've watched refineries burn, dams burst, buildings fall, roads wash away and yet the nuclear plant is still there and hasn't done any harm to anyone except apparently a few workers injured.

Psychologically I'm feeling a lot better about nuclear power today than I was last week. If you can hit a plant with a 9.0 and umpteen smaller aftershocks (6.0 and above) and a tsunami and have it explode and still not kill anyone then I'm confident we could have one near me where the worst it will get is some quite heavy rain.

So the earthquake and tsunami hits. The oil refineries go up in huge balls of fire, the dams break and add to the flooding, various other plants spew toxins everywhere, and people are worried about the safety of the nuclear power plants which haven't even melted down and will not explode?

Those plants got hit by a huge earthquake, and aftershocks, and all the other effects. If this isn't a great case for the safety of nuclear power plants, what is?

Exactly.

 

[Skwinty]

Here is a link with a good description of the BWR picture I posted earlier.

http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf

 

[LoudHoward]

yes i heard that too.

I've heard similar things, and that it's shaped so that the "melt" spreads out somewhat so it can cool quicker. Not sure if that's true though.

 

[Skwinty]

Here is a copy of an e-mail I received this morning.

What happened at Fukushima
I will try to summarize the main facts. The earthquake that hit Japan was 5 times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; the difference between the 8.2 that the plants were built for and the 8.9 that happened is 5 times, not 0.7). So the first hooray for Japanese engineering, everything held up.
When the earthquake hit with 8.9, the nuclear reactors all went into automatic shutdown. Within seconds after the earthquake started, the control rods had been inserted into the core and nuclear chain reaction of the uranium stopped. Now, the cooling system has to carry away the residual heat. The residual heat load is about 3% of the heat load under normal operating conditions.
The earthquake destroyed the external power supply of the nuclear reactor. That is one of the most serious accidents for a nuclear power plant, and accordingly, a “plant black out” receives a lot of attention when designing backup systems. The power is needed to keep the coolant pumps working. Since the power plant had been shut down, it cannot produce any electricity by itself any more.
Things were going well for an hour. One set of multiple sets of emergency Diesel power generators kicked in and provided the electricity that was needed. Then the Tsunami came, much bigger than people had expected when building the power plant. The tsunami took out all multiple sets of backup Diesel generators.
When designing a nuclear power plant, engineers follow a philosophy called “Defense of Depth”. That means that you first build everything to withstand the worst catastrophe you can imagine, and then design the plant in such a way that it can still handle one system failure (that you thought could never happen) after the other. A tsunami taking out all backup power in one swift strike is such a scenario. The last line of defense is putting everything into the third containment, that will keep everything, whatever the mess, control rods in our out, core molten or not, inside the reactor.
When the diesel generators were gone, the reactor operators switched to emergency battery power. The batteries were designed as one of the backups to the backups, to provide power for cooling the core for 8 hours. And they did.
Within the 8 hours, another power source had to be found and connected to the power plant. The power grid was down due to the earthquake. The diesel generators were destroyed by the tsunami. So mobile diesel generators were trucked in.
This is where things started to go seriously wrong. The external power generators could not be connected to the power plant (the plugs did not fit). So after the batteries ran out, the residual heat could not be carried away any more.
At this point the plant operators begin to follow emergency procedures that are in place for a “loss of cooling event”. It is again a step along the “Depth of Defense” lines. The power to the cooling systems should never have failed completely, but it did, so they “retreat” to the next line of defense. All of this, however shocking it seems to us, is part of the day-to-day training you go through as an operator, right through to managing a core meltdown.
It was at this stage that people started to talk about core meltdown. Because at the end of the day, if cooling cannot be restored, the core will eventually melt (after hours or days), and the last line of defense, the core catcher and third containment, would come into play.
But the goal at this stage was to manage the core while it was heating up, and ensure that the first containment (the Zircaloy tubes that contains the nuclear fuel), as well as the second containment remain intact and operational for as long as possible, to give the engineers time to fix the cooling systems.
Because cooling the core is such a big deal, the reactor has a number of cooling systems, each in multiple versions (the reactor water cleanup system, the decay heat removal, the reactor core isolating cooling, the standby liquid cooling system, and the emergency core cooling system). Which one failed when or did not fail is not clear at this point in time.
So imagine a pressure cooker on the stove, heat on low, but on. The operators use whatever cooling system capacity they have to get rid of as much heat as possible, but the pressure starts building up. The priority now is to maintain integrity of the first containment (keep temperature of the fuel rods below 2200°C), as well as the second containment, the pressure cooker. In order to maintain integrity of the pressure cooker (the second containment), the pressure has to be released from time to time. Because the ability to do that in an emergency is so important, the reactor has 11 pressure release valves. The operators now started venting steam from time to time to control the pressure. The temperature at this stage was about 550°C.
This is when the reports about “radiation leakage” starting coming in. I believe I explained above why venting the steam is theoretically the same as releasing radiation into the environment, but why it was and is not dangerous. The radioactive nitrogen as well as the noble gases do not pose a threat to human health.
At some stage during this venting, the explosion occurred. The explosion took place outside of the third containment (our “last line of defense”), and the reactor building. Remember that the reactor building has no function in keeping the radioactivity contained. It is not entirely clear yet what has happened, but this is the likely scenario: The operators decided to vent the steam from the pressure vessel not directly into the environment, but into the space between the third containment and the reactor building (to give the radioactivity in the steam more time to subside). The problem is that at the high temperatures that the core had reached at this stage, water molecules can “disassociate” into oxygen and hydrogen – an explosive mixture. And it did explode, outside the third containment, damaging the reactor building around. It was that sort of explosion, but inside the pressure vessel (because it was badly designed and not managed properly by the operators) that lead to the explosion of Chernobyl. This was never a risk at Fukushima. The problem of hydrogen-oxygen formation is one of the biggies when you design a power plant (if you are not Soviet, that is), so the reactor is built and operated in a way it cannot happen inside the containment. It happened outside, which was not intended but a possible scenario and OK, because it did not pose a risk for the containment.
So the pressure was under control, as steam was vented. Now, if you keep boiling your pot, the problem is that the water level will keep falling and falling. The core is covered by several meters of water in order to allow for some time to pass (hours, days) before it gets exposed. Once the rods start to be exposed at the top, the exposed parts will reach the critical temperature of 2200 °C after about 45 minutes. This is when the first containment, the Zircaloy tube, would fail.
And this started to happen. The cooling could not be restored before there was some (very limited, but still) damage to the casing of some of the fuel. The nuclear material itself was still intact, but the surrounding Zircaloy shell had started melting. What happened now is that some of the byproducts of the uranium decay – radioactive Cesium and Iodine – started to mix with the steam. The big problem, uranium, was still under control, because the uranium oxide rods were good until 3000 °C. It is confirmed that a very small amount of Cesium and Iodine was measured in the steam that was released into the atmosphere.
It seems this was the “go signal” for a major plan B. The small amounts of Cesium that were measured told the operators that the first containment on one of the rods somewhere was about to give. The Plan A had been to restore one of the regular cooling systems to the core. Why that failed is unclear. One plausible explanation is that the tsunami also took away / polluted all the clean water needed for the regular cooling systems.
The water used in the cooling system is very clean, demineralized (like distilled) water. The reason to use pure water is the above mentioned activation by the neutrons from the Uranium: Pure water does not get activated much, so stays practically radioactive-free. Dirt or salt in the water will absorb the neutrons quicker, becoming more radioactive. This has no effect whatsoever on the core – it does not care what it is cooled by. But it makes life more difficult for the operators and mechanics when they have to deal with activated (i.e. slightly radioactive) water.
But Plan A had failed – cooling systems down or additional clean water unavailable – so Plan B came into effect. This is what it looks like happened:
In order to prevent a core meltdown, the operators started to use sea water to cool the core. I am not quite sure if they flooded our pressure cooker with it (the second containment), or if they flooded the third containment, immersing the pressure cooker. But that is not relevant for us.
The point is that the nuclear fuel has now been cooled down. Because the chain reaction has been stopped a long time ago, there is only very little residual heat being produced now. The large amount of cooling water that has been used is sufficient to take up that heat. Because it is a lot of water, the core does not produce sufficient heat any more to produce any significant pressure. Also, boric acid has been added to the seawater. Boric acid is “liquid control rod”. Whatever decay is still going on, the Boron will capture the neutrons and further speed up the cooling down of the core.
The plant came close to a core meltdown. Here is the worst-case scenario that was avoided: If the seawater could not have been used for treatment, the operators would have continued to vent the water steam to avoid pressure buildup. The third containment would then have been completely sealed to allow the core meltdown to happen without releasing radioactive material. After the meltdown, there would have been a waiting period for the intermediate radioactive materials to decay inside the reactor, and all radioactive particles to settle on a surface inside the containment. The cooling system would have been restored eventually, and the molten core cooled to a manageable temperature. The containment would have been cleaned up on the inside. Then a messy job of removing the molten core from the containment would have begun, packing the (now solid again) fuel bit by bit into transportation containers to be shipped to processing plants. Depending on the damage, the block of the plant would then either be repaired or dismantled.
Now, where does that leave us? My assessment:

§ The plant is safe now and will stay safe.​

§ Japan is looking at an INES Level 4 Accident: Nuclear accident with local consequences. That is bad for the company that owns the plant, but not for anyone else.​

§ Some radiation was released when the pressure vessel was vented. All radioactive isotopes from the activated steam have gone (decayed). A very small amount of Cesium was released, as well as Iodine. If you were sitting on top of the plants’ chimney when they were venting, you should probably give up smoking to return to your former life expectancy. The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.​

§ There was some limited damage to the first containment. That means that some amounts of radioactive Cesium and Iodine will also be released into the cooling water, but no Uranium or other nasty stuff (the Uranium oxide does not “dissolve” in the water). There are facilities for treating the cooling water inside the third containment. The radioactive Cesium and Iodine will be removed there and eventually stored as radioactive waste in terminal storage.​

§ The seawater used as cooling water will be activated to some degree. Because the control rods are fully inserted, the Uranium chain reaction is not happening. That means the “main” nuclear reaction is not happening, thus not contributing to the activation. The intermediate radioactive materials (Cesium and Iodine) are also almost gone at this stage, because the Uranium decay was stopped a long time ago. This further reduces the activation. The bottom line is that there will be some low level of activation of the seawater, which will also be removed by the treatment facilities.​

§ The seawater will then be replaced over time with the “normal” cooling water​

§ The reactor core will then be dismantled and transported to a processing facility, just like during a regular fuel change.​

§ Fuel rods and the entire plant will be checked for potential damage. This will take about 4-5 years.​

§ The safety systems on all Japanese plants will be upgraded to withstand a 9.0 earthquake and tsunami (or worse)​

§ (Updated) I believe the most significant problem will be a prolonged power shortage. 11 of Japan’s 55 nuclear reactors in different plants were shut down and will have to be inspected, directly reducing the nation’s nuclear power generating capacity by 20%, with nuclear power accounting for about 30% of the national total power generation capacity. I have not looked into possible consequences for other nuclear plants not directly affected. This will probably be covered by running gas power plants that are usually only used for peak loads to cover some of the base load as well. I am not familiar with Japan’s energy supply chain for oil, gas and coal, and what damage the harbors, refinery, storage and transportation networks have suffered, as well as damage to the national distribution grid. All of that will increase your electricity bill, as well as lead to power shortages during peak demand and reconstruction efforts, in Japan.​

§ This all is only part of a much bigger picture. Emergency response has to deal with shelter, drinking water, food and medical care, transportation and communication infrastructure, as well as electricity supply. In a world of lean supply chains, we are looking at some major challenges in all of these areas.​

If you want to stay informed, please forget the usual media outlets and consult the following websites:

§ http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html​

§ http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303111.html​

§ http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/​

§ http://ansnuclearcafe.org/2011/03/11/media-updates-on-nuclear-power-stations-in-japan/​

 

[Sword_Of_Truth]

Here is a copy of an e-mail I received this morning.

What happened at Fukushima
If you want to stay informed, please forget the usual media outlets and consult the following websites:

§ http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html
§ http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303111.html
§ http://bravenewclimate.com/2011/03/12/japan-nuclear-earthquake/
§ http://ansnuclearcafe.org/2011/03/11/media-updates-on-nuclear-power-stations-in-japan/​

That right there is the most important part of your post. Whatever you do, avoid the mainstream media and DC's "experts".

 

[Darat]

I was listening to a harrowing account of an elderly women looking through the wreckage of her home for her husband's medal (he had died 100 days before) and one of the journalist's descriptions turned to the globules of tarry petrochemicals dripping from everywhere. The local refinery had exploded before catching fire, how much damage is that type of pollution going to cause?

Yes a nuclear reactor malfunctioning is very worrying - especially one so old - but I suspect that compared to the pollution caused by everything else as a result of the tsunami and earthquake it will be almost insignificant.

 

[a_unique_person]

They couldn't just hardwire the backup generators?

 

[Soapy Sam]

They couldn't just hardwire the backup generators?

Depends what was damaged. Fuel? Wiring? Pipework? Valves? Generators themselves? Mountings? Prop shafts? Even pumping seawater will be problematical, because of debris blocking filters .The seabed for miles has been churned. They may be pumping a mud slurry rather than water. That takes specialised pumps- and even those need frequent maintenance. Believe me. I pump mud for a living. Power station equipment and drilling rig mud pumps are very different.

 

[DC]

That right there is the most important part of your post. Whatever you do, avoid the mainstream media and DC's "experts".

still more preferable that the unqualified comments from the postoffice guy....

 

[a_unique_person]

Depends what was damaged. Fuel? Wiring? Pipework? Valves? Generators themselves? Mountings? Prop shafts? Even pumping seawater will be problematical, because of debris blocking filters .The seabed for miles has been churned. They may be pumping a mud slurry rather than water. That takes specialised pumps- and even those need frequent maintenance. Believe me. I pump mud for a living. Power station equipment and drilling rig mud pumps are very different.

The emergency generators they brought in after the quake. They said they couldn't use them because the plug didn't fit.