Faulty hydrogen vents at Fukushima Daiichi spell trouble for US nuclear plants as well

Logs from the hours following the 9.0 magnitude earthquake and tsunami that struck the Fukushima Daiichi nuclear plant and interviews with workers show that US-designed hydrogen vents malfunctioned, leading to devastating pressure buildups and explosions at three of the plant’s six reactors, causing massive released of radiation.

The failure of the vents calls into question the safety of similar nuclear power plants in the United States and Japan.

After the venting failed at the Fukushima Daiichi plant, the hydrogen gas fueled explosions spewed radioactive materials into the atmosphere, reaching levels about 10 percent of estimated emissions at Chernobyl – or 5 million Curies – according to Japan’s nuclear regulatory agency.

Hydrogen venting – though it releases radiation – was critical to reliving intense pressure building up in reactor Nos 1, 2 and 3 at the plant after the March 11 tsunami knocked out all power to the cooling systems to the reactors. As cooling water stopped flowing through the reactors, they began to dangerously overheat.

Bellona nuclear physicist Nils Bøhmer said that in such circumstances, venting is the lesser of two evils.

“If [the venting] had worked it would have minimized the accident,” he said. “But since it failed, the reactors exploded, releasing far more radioactivity into the environment.”

Bellona

What I can't believe is they couldn't decide to vent the reactors for 17hours knowing the outcome of not venting them would be complete reactor vessel failure. WTF!!!

And then it took another 6 hours to impliment that order only to find out the venting system didn't work.

They also knew the Mark 1 reactor design was severly flawed due to the small containment vessel size that couldn't handle pressure build ups from loss of coolent. A few of the guys that designed the Mark 1 quit their jobs in protest due to this oversight.

These same vents are still in use in the USA today despite TPTB saying they have new, better vents.

This article has a great time line of the early events from Fukushima's own logs.

Originally posted by FreeSpeaker
Bellona

What I can't believe is they couldn't decide to vent the reactors for 17hours knowing the outcome of not venting them would be complete reactor vessel failure. WTF!!!

And then it took another 6 hours to impliment that order only to find out the venting system didn't work.

It seems to me like the article is misleading. Did you see this part?

TEPCO has said that one reason the GE designed vents did not work is because they relied on the same source of power as the rest of the plant – the aged backup generators in basements that were disabled by an inundation of water.

And they they go on to say they could be operated manually but they didn't operate the manual controls because they couldn't get close enough due to the radiation.

Isn't this a bit like claiming your toaster doesn't work when you have a power outage at home? The toaster isn't defective, but it was designed to use electricity and it won't work without it. Saying the toaster is defective when it doesn't work without power seems to me to be what they are trying to do here, or am I missing something?
It seems the problem was a lack of power. Why don't they claim the cooling pumps were defective too, they also needed power to operate?

They also knew the Mark 1 reactor design was severly flawed due to the small containment vessel size that couldn't handle pressure build ups from loss of coolent. A few of the guys that designed the Mark 1 quit their jobs in protest due to this oversight.

That's a disturbing theme I've seen reported in numerous places. It seems there were numerous design flaws though it probably won't be for another 5-10 years that a full investigation details it for us. It would be interesting to hear interviews from the guys that resigned to see what they have to say about it.

Originally posted by Arbitrageur
Isn't this a bit like claiming your toaster doesn't work when you have a power outage at home? The toaster isn't defective, but it was designed to use electricity and it won't work without it. Saying the toaster is defective when it doesn't work without power seems to me to be what they are trying to do here, or am I missing something?

You missed a tiny part.

TEPCO has said that one reason the GE designed vents did not work is because they relied on the same source of power as the rest of the plant – the aged backup generators in basements that were disabled by an inundation of water. TEPCO also reported that the earthquake could have damaged valves that are a part of the hydrogen venting system.

It seems a flooded basement and earthquake damage is the prime culprit. I also imagine there was probably electrical malfunctions due to the flooding.

Originally posted by Arbitrageur
It would be interesting to hear interviews from the guys that resigned to see what they have to say about it.

I don't know how public they have gone but I have ordered and look forward to Mitsuhiko Tanaka's "Why Nuclear Power is Dangerous". Should be a very interesting read.

Mitsuhiko Tanaka, an engineer who was responsible for implementing the GE Mark 1 design at the Fukushima Daiichi plant in the early 1970s, said in a recent interview that for 40 years, he and others knew the reactor design to be faulty because its containment vessel is too small to adequately withstand the kinds of pressure buildups that bore out at reactor Nos 1, 2, and 3.

Tanaka' blew the whislte after chernobyl and has called himself the "godfather of Japan's chernobyl" after the Fukushima accident.

Originally posted by FreeSpeaker
You missed a tiny part.

TEPCO has said that one reason the GE designed vents did not work is because they relied on the same source of power as the rest of the plant – the aged backup generators in basements that were disabled by an inundation of water. TEPCO also reported that the earthquake could have damaged valves that are a part of the hydrogen venting system.

It seems a flooded basement and earthquake damage is the prime culprit. I also imagine there was probably electrical malfunctions due to the flooding.

Yes I agree with your latter statement.

But no I didn't really miss that about the Earthquake damage. I still am not sure I'd characterize the vents as "faulty" just because they were damaged by the earthquake, UNLESS perhaps the valves were certified to survive a 9.0 earthquake but I don't think any nuclear plants are designed to withstand 9.0 earthquakes, at least none that I know of:

The magnitude 9 earthquake that struck a Japanese nuclear plant in March hit with almost 30 percent more intensity than it had been designed to withstand, raising the possibility that key systems were compromised even before a massive tsunami hit.

So, based on this information, I would agree with an assessment that the entire facility was faulty because the design criteria were insufficient. But this still doesn't explain why they would single out the vents, in fact it points to the opposite conclusion, that is, that perhaps the vents were NOT faulty. If they were made to design specifications and then those design specifications were exceeded, then that's not a fault with the vents, that's a fault with the design, right? Which applies to the entire plant and not just the vents.

the aged backup generators in basements that were disabled by an inundation of water.

Ok so let me get this straight. They had Diesel Generators in the basement of a building by an oceanic area that is prone to Tsunami's.

AND

They had spent fuel rods that need to be kept water cooled in the ceiling.

Gotcha.

What we have here is total lunacy. This isn't 'mechanical' or 'electical' failure. The real failure is in the complete idiotic lunacy of the people who planned this op and should be skinned before being hung by the balls.

.

Originally posted by Stratus9
Ok so let me get this straight. They had Diesel Generators in the basement of a building by an oceanic area that is prone to Tsunami's.

Well, in their defense, the stone tsunami marker up on the hillside only said to not build houses below this point, it didn't say anything about nuclear power plants:

theomnireport.blogspot.com...
[atsimg]http://files.abovetopsecret.com/images/member/de98459d4524.jpg[/atsimg]

This centuries old stone monument in Aneyoshi reads:
"High dwellings are the peace and harmony of our descendants.
Remember the calamity of the great tsunamis.
Do not build any homes below this point."

Of course centuries ago when they made that marker, they didn't even know what nuclear power was, so it was kind of hard to include that on the warning!

But that's not the only one, there are hundreds of them:

Hundreds of stone markers dot the Japanese coastline warning the dangers of a tsunami. Some of these markers are by all accounts well over 600 years old.

So yeah, it does sort of fall into the category of "what were they thinking?".

Originally posted by Arbitrageur
So, based on this information, I would agree with an assessment that the entire facility was faulty because the design criteria were insufficient. But this still doesn't explain why they would single out the vents, in fact it points to the opposite conclusion, that is, that perhaps the vents were NOT faulty. If they were made to design specifications and then those design specifications were exceeded, then that's not a fault with the vents, that's a fault with the design, right? Which applies to the entire plant and not just the vents.

I think your right on the money, the entire Mark 1 design is faulty. What I can't understand is why the vents at #2&3 didn't work when they were opened manualy?

As efforts to manually open the vents at reactor No 1 failed because of spiraling radiation level, workers at reactor No 2 also tried to manually open its venting system. Pressure in the reactor did not fall though, so it was unclear whether the venting had succeeded the records show. At reactor No 3, manual attempts to open the vents failed, said the records.

We obviously need more information because those opened vents should have worked. Did the efforts to open the vents at 2&3 fail or succeed with no effect? We need to know how and why they failed. Is it possible contamination from the use of salt water in the reactor plugged the vents? I'm not sure of the timeline when they started pumping in saltwater in relation to the venting efforts.

A little digging has uncoverd some scary facts.

As early as 1972, Dr. Stephen Hanauer, an Atomic Energy Commission safety official, recommended that the pressure suppression system be discontinued and any further designs not be accepted for construction permits. Hanauer's boss, Joseph Hendrie (later an NRC Commissioner) essentially agreed with Hanauer, but denied the recommendation on the grounds that it could end the nuclear power industry in the U.S.

Here are copies of the three original AEC memos, including Hendrie's:

November 11, 1971: outlines problems with the design and pressure suppression system containment.

September 20, 1972: memo from Steven Hanauer recommends that U.S. stop licensing reactors using pressure suppression system

September 25, 1972: memo from Joseph Hendrie (top safety official at AEC) agrees with recommendation but rejects it saying it "could well mean the end of nuclear power..."

In 1976, three General Electric nuclear engineers publicly resigned their prestigious positions citing dangerous shortcomings in the GE design.

An NRC analysis of the potential failure of the Mark I under accident conditions concluded in a 1985 report that Mark I failure within the first few hours following core melt would appear rather likely."

In 1986, Harold Denton, then the NRC's top safety official, told an industry trade group that the "Mark I containment, especially being smaller with lower design pressure, in spite of the suppression pool, if you look at the WASH 1400 safety study, you'll find something like a 90% probability of that containment failing." In order to protect the Mark I containment from a total rupture it was determined necessary to vent any high pressure buildup. As a result, an industry workgroup designed and installed the "direct torus vent system" at all Mark I reactors. Operated from the control room, the vent is a reinforced pipe installed in the torus and designed to release radioactive high pressure steam generated in a severe accident by allowing the unfiltered release directly to the atmosphere through the 300 foot vent stack. Reactor operators now have the option by direct action to expose the public and the environment to unknown amounts of harmful radiation in order to "save containment." As a result of GE's design deficiency, the original idea for a passive containment system has been dangerously compromised and given over to human control with all its associated risks of error and technical failure.

As we have now seen at Fukushima, Japan, in March 2011, this containment design failed catastrophically when hydrogen built up in the outer containment buildings until three of them exploded. The outer containment building was neither large enough nor strong enough to withstand these explosions.

HAZARDS OF BOILING WATER REACTORS IN THE UNITED STATES

Well there you have it. In 1972 Joseph Hendrie (top safety official at AEC) agrees with the recommendation that U.S. stop licensing reactors using pressure suppression system but rejects it saying it "could well mean the end of nuclear power...". In 72' they knew this design was severly flawed but greed wins out as usual.

If you take a look at THIS DESIGN PICTURE you will see the vents are at the bottom of the reactor. I'm no engineer but wouldn't putting the vents at the top be better as that is where the gas escapes the reactor? Not only that but with the vents at the bottom there is a much greater risk of them being obstructed by damage from inside the reactor or saltwater blockage.

Originally posted by FreeSpeaker
If you take a look at THIS DESIGN PICTURE you will see the vents are at the bottom of the reactor. I'm no engineer but wouldn't putting the vents at the top be better as that is where the gas escapes the reactor? Not only that but with the vents at the bottom there is a much greater risk of them being obstructed by damage from inside the reactor or saltwater blockage.

One of my degrees is in engineering, so I'll have a look, but the drawing you linked to isn't detailed enough. Just from that sketch it does seem like an odd place to put the vents but I need to see more detail which might show the logic behind it.

I scrolled down from that drawing and found a link to another document that has more detail, but the pdf has 74 pages and I'm only on page 9/74 so far:

www.ansn-jp.org...

One thing that strikes me as odd about page 9 of that pdf (page 6 on the document numbers), is they mention "conservative design" as one of the safety factors, when as far as I can tell, the competing designs were conservative, but not this one, so that seems pretty ironic.

The thing that really strikes me as odd is how wimpy the containment is on these reactors, and everyone seemed to know it, which is pretty disgusting actually.

Anyway, thanks for posting the informative link, I'm interested in this stuff.

I studied those more detailed blueprints and wasn't sure why the vents are located where they are, though a new video from Arnie Gunderson may help explain that:

The Implications of the Fukushima Accident on the World's Operating Reactors
vimeo.com...

He claims that the vents aren't part of the original design and they actually violate US NRC regulations, and he shows an enlargement of the applicable regulation in the video.

He claims the vents were a band-aid after the plants were already built and the NRC granted a waiver to their own regulation even though the design is inherently unsafe.

Now the odd vent design begins to make more sense to me, but the irresponsibility of the NRC is striking on this and other issues which Gunderson highlights in that video. It seems like the NRC isn't doing a very good job according to Gunderson. That's scary. He even shows photos of cracked containment vessels found on US reactors. Cracked apparently just from age and not from any earthquake!

Out of 104 US reactors only 31 have this problem. these are first generation reactors

And they are ending there life cycle and will be shut down in the near future or modernised.

The road block in the US on these vents was not the reactor operating companies.

The NRC is the one that did not allow these vents because they did not want the hydrogen vented as it might contain radioactive particles.

Many of the 2ed and 3ed generation reactors have built in filter units to remove any radioactive particles.

Plus US reactors do not store spent fuel rods in the reactor building..

Originally posted by ANNED
Plus US reactors do not store spent fuel rods in the reactor building..

Yes that seems like a really bad practice.

I hope Japan reconsiders their policy on this going forward and adopts a policy more like the US in this regard.