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Stress test results for nuclear power plant in Ehime released

20 Comments

Shikoku Electric Power Co on Monday announced the results of stress tests on a suspended nuclear reactor at its Ikata plant in Ehime Prefecture. The utility handed the report to the Nuclear and Industrial Safety Agency, which is overseen by the Economy, Trade and Industry Ministry.

According to NHK, the report says the No. 3 reactor can withstand an earthquake 1.86 times the strongest assumed level of 570 gals. It also said that the plant would be able to withstand tsunami waves as high as 14.2 meters.

The report is the second one to be submitted on the results of stress tests following Kansai Electric Power Co, which conducted tests on its Oi nuclear power plant in Fukui Prefecture in October.

In July, the government ordered utility companies to conduct the stress tests on all the country's nuclear plants to ease heightened concerns about disaster preparedness.

The March 11 earthquake and tsunami in northeastern Japan knocked out power at the Fukushima Daiichi nuclear power plant, sending it toward meltdown in a crisis that engineers are still struggling to contain. The plant operator, Tokyo Electric Power Co, has come under heavy criticism for failing to sufficiently prepare for the disasters.

More than two-thirds of Japan's 54 reactors remain offline. Utilities with plants that were shut down for safety reviews after the crisis or that already had been offline due to routine maintenance have been reluctant to restart them because of public anxiety and anti-nuclear protests.

The stress tests incorporate elements from those ordered by the European Union on the 143 nuclear plants in that region after the Fukushima crisis.

Those reviews, which started June 1, are supposed to consider the impact of both natural and man-made events such as airplane crashes and terrorist attacks.

Nuclear power generates about 30% of Japan's electricity.

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According to NHK, the report says the No. 3 reactor can withstand an earthquake 1.86 times the strongest assumed level of 570 gals.

Smoke and mirrors, use units that normal people can understand please.

1.86*570 gals=1060 gals

The strongest recorded peak ground acceleration during the Tohoku earthquake was 2.7g single direction and 2.99g vector sum.

1g=981 gals, so 2.7g equals 2649 gals and 2.99 would be 2933 gals That's nearly three times as high as the level being tested in the stress test.

For reference, Shindo 7 starts somewhere around 400gals, but it has no upper limit.

On top of that these "stress tests" are not really tests at all they are calculations and simulations. The models used may be well understood, but then you also need to trust that no one took any short cuts during the construction.

3 ( +5 / -2 )

http://www.kyoshin.bosai.go.jp/kyoshin/topics/html20110311144626/main_20110311144626.html

Left figure shows areas with more than 2000gals during Tohoku earthquake, colored red.

0 ( +2 / -2 )

I don't understand the meaning of the units?

The last line in the post, atomic power was generating about 24% of total power prior to 3/11 which dropped to about 18% during the summer, and is now less than 16%.

All reactors older than 30-years shut be shut down.

At this plant there are three reactors, No1 which is 34-years (1977), No2 which is 29-years (1982), No3 17-years (1994).

2 ( +4 / -2 )

@zichi,

1g = 9.81 m/s2 = 981 gal (Or actually Gal, I think but article uses gals)

Well Kobe earth quake saw ground accelerations at about 0.8 g which would be equal to 784 Gal. But the Tohoku earth quake saw ground acceleration peaks at 2000 to 3000 Gal.

In this context, testing reactors for 570 Gal level seems inadequate. In my opinion this is like a teacher selecting a passing grade for a test which he knows all his students will be able to pass.

2 ( +4 / -2 )

SquidBert, thank you.

So many new units to take in these days, becquerels, sieverts and gals.

The Fukushima plant was build to withstand a 7.6 mag quake, which wasn't enough. When it comes to a very dangerous plant, like an atomic power plant, they should exceed the possibility of the strongest quake.

2 ( +4 / -2 )

Some questions:

what are the results for reactors No.1 and 2 ?

what were the pass marks for each test?

which elements were taken from the European stress tests and which were not? Can we have a detailed list of all the elements tested? Does it include only earthquake/tsunami resistance or also risks of plane crash / terrorist attacks?

can we have a schedule for the stress tests all over Japan?

are the stress test results legally binding (ie no authorization to restart after a failed test)?
0 ( +2 / -2 )

@zichi

When it comes to a very dangerous plant, like an atomic power plant, they should exceed the possibility of the strongest quake.

Yes, I would imagine this to be true in any other country. Usually Hospitals, bridges and other important structures should be engineered to hold for the "Maximum Considered Event". I imagine(or at least naively hope) that Nuclear reactors be designed to hold at least this standard in other countries.

Wikipedia defines this as:

In a normal seismic hazard analyses intended for the public, that of a "maximum considered earthquake", or "maximum considered event" (MCE) for a specific area, is an earthquake that is expected to occur once in approximately 2,500 years; that is, it has a 2-percent probability of being exceeded in 50 years.

So even in this standard we see a 2 percent probability of exceeding the level in 50 years. But earthquakes exceeding 570 Gal is a (in these terms) common event in Japan. It has occurred at least 6 times since 1995 (Kobe).

0 ( +2 / -2 )

The stress test's criteria were designed in central Europe. I think Germany has the strongest fingerprint on them. You can see that from the plane crash scenario. No other country ever simulated that (or took it serious at all) except Germany. The result was the immediate, permanent shutdown of the eight oldest reactors because it was considered economical nonsense to fortify them.

Even though central Europe has geologically active zones, they are rather harmless in comparison to Japan. Germany, to return to the previous example, shut down a few of its reactors due to (initially underestimated) earthquake risk. To put the 1000 gal (~10 m/ s^2 in metric units) into a meaningful context, I'll post a few examples.

Sprinting Usain Bolt accelerates about 400 gal, when he starts.

Middle class cars can accelerate with about 500 gal.

Maximal acceleration in a a shot push are about 1000 gal.

Typical decelerations in cars are at most about 1050 gal (without a crash).

Rollercoasters can do about 4000 gal.

A typical rocket start has between 4000 and 6000 gal.

A sewing machine's needle is subjected to about 6000000 gal.

Tennis balls suffer about 10^7=10000000 gal when hit full force.

A nuclear explosion accomplishes 1^14=100000000000000 gal.

The most fragile parts of the human body survive about 15000 gal.

Therefore, 570 gal for a nuclear plant is a joke.

1 ( +2 / -1 )

Piglet,

all reactors have to be tested. Only the governor of the prefecture can give permission to restart a reactor.

This is a first test and if started up the power companies must perform a second test.

1 ( +2 / -1 )

Let me guess, this reactor and all the other reactors will be assessed as 'safe for operation'

2 ( +2 / -0 )

Let's hope none of the test results were falsified, like TEPCO did; and that the plant has been built to the proper spec, unlike Fukushima, which had one dryer unit on 180 degrees the wrong way, and a defect/ large dent in one of the reactor pressure vessels, also covered up by TEPCO and the makers.

@zichi - I'm not sure if the governor of the prefecture legally needs to give permission to the Utility to restart a reactor, but the utilities like to ask for it to demonstrate some sort of official support.

0 ( +0 / -0 )

The major weak link is that the stress test and other safety checks are made by the power company which owns the plant.

wanderlust,

I don't know the law regarding governors and starting reactors, but I think it must be so because the Kansai power company have been trying for months to get permission to restart their reactors. So why don't they just restart then?

3 ( +3 / -0 )

The strongest recorded peak ground acceleration during the Tohoku earthquake was 2.7g single direction

Might be worth considering that Ehime is not in Tohoku and isn't a hugely earthquake prone area for large shakes.

0 ( +0 / -0 )

Therefore, 570 gal for a nuclear plant is a joke

That is the largest earthquake likely to hit the area, NOT the plant's limit.

0 ( +0 / -0 )

http://www.kyoshin.bosai.go.jp/kyoshin/topics/html20110311144626/main_20110311144626.html Left figure shows areas with more than 2000gals during Tohoku earthquake, colored red.

Scary to see just how much of the country shook violently from a single earthquake!!!

0 ( +0 / -0 )

@zichi - maybe because this is the first stress test result to be actually completed, and that has been mandated by central J-gov?

From an article on the Tomari reactor in Hokkaido, which has recently re-started, after the adjustment period: According to NISA the reactor could safely be restarted, but Hokkaido governor criticized the operator for submitting the application before it had reached its own decision on restarting (the Japanese law does not require local governments' agreement to restart nuclear reactors, but in practice both government and nuclear operators have always respected their will).

1 ( +1 / -0 )

@Yidray

Might be worth considering that Ehime is not in Tohoku and isn't a hugely earthquake prone area for large shakes.

Don't know about that, it is closer to the Tectonic plate boundary than Kobe. Tohoku was also not supposed to produce this level of quake, remember?

That is the largest earthquake likely to hit the area, NOT the plant's limit. It seems the test went to 1.86 the assumed value. Don't know if that was the failure point, or they just didn't test higher values.

Still 1.86 * 570 gal is nowhere near the safety marginals you would want for a NPP. As I said before, Kobe saw at least 780gal in 1995

0 ( +0 / -0 )

Since Japan is basically one massive earthquake zone, every reactor needs to be built or upgraded to withstand a powerful quake.

TEPCO made billions and billions of profit out of Fukushima. Had it upgraded the plant has requested by NISA, there might be no nuclear disaster.

The country can't leave it up to chance.

5 ( +5 / -0 )

wanderlust,

Thank you for the info, must be so then.

0 ( +0 / -0 )

570 Gal? Huh? Some stress, not.

Kashiwazaki-Kariwa No 1 reactor was hit by 680 Gal East-West movement when they had that totally unexpected earthquake in... 1997(?)

Interesting read: http://cnic.jp/english/newsletter/nit119/nit119articles/kkearthquake.html

0 ( +0 / -0 )

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