The fuel rod storage ponds are heating up

by Arenamontanus

IAEA Update on Japan Earthquake
[Via IAEA]

Temperature of Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant

Spent fuel that has been removed from a nuclear reactor generates intense heat and is typically stored in a water-filled spent fuel pool to cool it and provide protection from its radioactivity. Water in a spent fuel pool is continuously cooled to remove heat produced by spent fuel assemblies. According to IAEA experts, a typical spent fuel pool temperature is kept below 25 ˚C under normal operating conditions. The temperature of a spent fuel pool is maintained by constant cooling, which requires a constant power source.

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Units 4, 5, 6 were shut down before the quake so there should not be any worry about their reactors. But, the spent fuel rods from unit 4 were placed in storage ponds to continue cooling down. These ponds, on the roof of the building, are kept cool by pumps, pumps that no longer work because there is no electricity to them.

It appears the ponds are now becoming a problem, especially unit 4. If the water boils off, the fuel rods will begin to overheat and possibly degrade, releasing radioactive material. While potentially not as bad as released from fuel rods in the reactor, the worry comes because there is no containment vessel at all over the storage ponds. They may actually be open to the sky now after the explosions and fires seen in the top of every unit.

The only thing preventing degradation of the rods and release of radiation from the ponds then is the water above the rods. There is supposed to be 5 meters above them but today, the IAEA minister said that there was 1-2  meters. That is much much less than expected. No wonder they just want to drop water on top of the ponds. Anything to add water.

Now look at the table of temperatures the IAEA post gave for water temperatures in the ponds of units 4, 5, 6:

Unit 4
14 March, 10:08 UTC:	84 ˚C
15 March, 10:00 UTC:	84 ˚C
16 March, 05:00 UTC:	no data
Unit 5
14 March, 10:08 UTC:	59.7 ˚C
15 March, 10:00 UTC:	60.4 ˚C
16 March, 05:00 UTC:	62.7 ˚C
Unit 6
14 March, 10:08 UTC:	58.0 ˚C
15 March, 10:00 UTC:	58.5 ˚C
16 March, 05:00 UTC:	60.0 ˚C

Water boils at 100 °C but it will evaporate pretty fast at 84 °C. Unit 4 is at least holding still, probably because so much effort has been expended on it. Units 5 and 6 are seeing increasing temperature but Tepco should have some time.

It would be very ironic if, in the end, it is not the active reactors that were the main problem but  the storage ponds of mostly spent fuel.

I really hope they get electricity going there soon and get water on top of the storage ponds. I’ll feel a little more comfortable.

You knew this was coming – TSA gets radiation dose from backscatter machines wrong

TSA admits bungling of airport body scanner radiation tests
[Via Ars Technica]

The Transportation Security Administration is reanalyzing the radiation levels of X-ray body scanners installed in airports nationwide, after testing produced dramatically higher-than-expected results.

The TSA, which has deployed at least 500 body scanners to at least 78 airports, said Tuesday the machines meet all safety standards and would remain in operation despite a “calculation error” in safety studies. The flawed results showed radiation levels 10 times higher than expected.

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But the way they were wrong is not expected. In some cases, they had radiation levels that were ten times higher than reality. That is they overstated the radiation dose.

What happened was that testers were supposed to take ten readings, add them up and divide by ten to get the average dose. Sometimes they forgot to divide by 10.

So, we can be upset they did not catch this sooner but the error they made was not one that would be harmful. Of course, the next time they make a math error we might not be as lucky.

What BP was to oil, Tokyo Electric Power may be to nuclear

by Andy Beez

BBC News – Is Tokyo Electric Power becoming Japan’s BP?
[Via BBC]

The unfolding disaster at Japan’s Fukushima nuclear power complex has focused attention on the site’s operator – the Tokyo Electric Power Company.

It is hard not to have some sympathy for Tepco, as the company is known, as its engineers are racing to avoid catastrophic meltdowns at nuclear plants in Japan.

Much like oil giant BP – which found itself at the centre of a storm when a blast at a rig killed 11 people and caused the worst oil spill in US history off the Gulf of Mexico – Tepco finds itself struggling to cope with a situation it never saw coming.

Public relations must rank low on the list of priorities as it battles to contain the unimaginable amid the devastation caused by a massive earthquake and the subsequent tsunami.

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Tepco has a history of safety violations such as false reporting of inspections. Now it has ample pressure to not let outsiders get accurate information of a problem that appears to be moving faster than they can cope with. The Prime Minister was furious that he was informed of developments hours after they occurred.

I would not be surprised to see that, as with BP, Tepco ignored safety protocols because they found them inconvenient.

Using the same logic as used with the Challenger disaster – nothing bad has happened so far so why follow the protocols that just get in the way.

With BP, it was probably an inadeguate blowout preventer along with poorly executed safety procedures. I wonder what it will be here?

In any case, BP’s idiocy hurt the entire industry, which has still not been able to drill in the deep Gulf. Tepco’s disaster will have an even larger effect on nuclear power, I fear.

A great background on spent fuel storage ponds

What are Spent Fuel Pools? | MIT NSE Nuclear Information Hub (http://web.mit.edu/nse/)
[Via MIT Nuclear Science]

Spent nuclear fuel (SNF) refers to fuel after it has fuelled a reactor.  This fuel looks like new fuel in the sense that it is made of solid pellets contained in fuel rods.  The only difference is that SNF contains fission products and actinides, such as plutonium, which are radioactive, meaning it needs to be shielded.   Just as with the fuel rods in a shutdown reactor, the SNF produces decay heat because most of the decay radioactivity from the fission products and actinides is deposited in the fuel and converted into thermal energy (aka heat).   As a result, the SNF also needs to be cooled, but at a much lower level than fuel in a recently (<12 hours) shutdown reactor as it produces only a fraction of the heat.   In summary, the SNF is stored for a certain time to: 1) allow the fuel to cool as its decay heat decreases; and 2) shield the emitted radiation.

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This provides a lot more background on the storage ponds and the possible dangers.

They simply have to keep lots of water over the rods. If not, they could be in trouble.

This MIT site is a great place to get information about what is going on. It is one of my mainstays next to the BBC and the IAEA website.

Update: Worry about the storage ponds

by pasukaru76 (sry bad internet)

BBC News – Surprise ‘critical’ warning raises nuclear fears
[Via BBC]

This is a surprise.

Reactors 4, 5 and 6 were shut down at the time of Friday’s earthquake, with some or all of their fuel rods extracted and left in cooling ponds that each reactor building has under its roof.

Once a reactor is turned off, radioactivity and heat generation in the rods die away quickly; down to 7% of the original power within a second of switch-off, 5% within a minute, 0.5% within a day.

Continue reading the main story “ Start Quote

The moment when fuel rods are covered with water, the situation is basically stabilised”

Jasmina Vujic University of California Transferred to the cooling pond, allowing technicians to do routine maintenance on the reactor, the rods are supposed to sit quietly until the time comes for their re-insertion or their journey towards disposal.

The tops of the rods are supposed to be about 5m (16ft) below the water surface.

The water keeps them cool and also blocks the release of gamma rays that would harm people in the vicinity.

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I’ve been worried about this for a couple of days. They have had fires at the storage ponds, where spent fuel rods are stored. There have been reports that the water in the ponds is boiling, that large amounts of the cooling water surrounding the rods has disappeared, placing the rods perilously close to be exposed to the air.

Why the rods seem to be heating up the ponds is unclear but a big cause of concern for me. The IAEA reported yesterday that the water in the storage pond for unit 5 is not 5 meters about the rods but only 2 meters. And that there was a 0.4 meter drop in the level in a 5 hour period. Why is the Unit 5 storage pond even involved?

How far down the safety process does one have to go to get to using helicopters to provide the water needed for the storage ponds?

Unit 4 was shut down at the time of the quake and its spent rods put in the storage pond. It the rods are exposed to the air, there will very likely be release of nasty radioactive isotopes. Probably not as many as would be if the reactor containment vessel blew up. But because the storage ponds have no containment at all, any release is a problem.

So watch what they say about the storage ponds. I think the problems there are unexpected and thus not in the highly redundant safety plans they are operating on.

[Update: Here is a great background on storage ponds.]

Cables released by Wikileaks indicate that international agencies were worried about the safety of Japan’s nuclear power plants

Japan earthquake: Japan warned over nuclear plants, WikiLeaks cables show – Telegraph
[Via Telegraph]

An official from the International Atomic Energy Agency (IAEA) said in December 2008 that safety rules were out of date and strong earthquakes would pose a “serious problem” for nuclear power stations. The Japanese government pledged to upgrade safety at all of its nuclear plants, but will now face inevitable questions over whether it did enough

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This will not help people trust what either the utilities or the government say. They had only updated the safety guides fro seismic safety only 3 times in 35 years.  That does not really show a very strong focus on earthquakes.

This could really have an effect on Japan’s government and for anyone involved with these previous concerns.

Would knowing that a 9 quake occurs every 1000 years have changed any planning?

by NASA Goddard Photo and Video

Tsunami could be 1,000-year event
[Via BBC News | Science/Nature | World Edition]

Tsunamis on the scale that hit north-east Japan last week may strike the region about once every 1,000 years, a leading seismologist has said.

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In the last 3000 years, there have apparently been 4 very large quakes/tsunamis in this area of Japan.  Thus there is roughly a 0.13% chance each year. Would Japan have built the nuclear power plants where they did with the understanding that during the plant’s lifetime – 40 years -, there might be a 5.3% chance of such a catastrophe?

And the rule of thumb from the seismologist is that for every 1 quake at 8, there would be 10 at 8 and 100 at 7. A simple calculation by these numbers would indicate that there would be a 53% chance of a quake with strength of 8 during the lifetime of this plant. Is that an acceptable risk?

I’d like think that a 50-50 chance of the nuclear plant being hit by an earthquake of 8 on the Richter scale – with the corresponding tsunami – would have resulted in a different siting of the plant.

Denying facts in the House

Next up for Congress: repeal the law of gravity
[Via Bad Astronomy]

Today, House Republicans made it clear just how antiscience they are (as if we didn’t know already): they voted down a simple amendment declaring the reality of climate change. Not that it was human-caused, or dangerous, just that it existed. Which it does.

The amendment was presented by Henry Waxman (D-CA) to the Energy and Commerce Committee. All the Democrats voted for it, all the Republicans voted against it. So there you go. As Waxman said,

This finding is so obviously correct that there should be no need to offer the amendment.

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The GOP members of the committee, all 31 of them, refuse to even acknowledge that climate change is actually happening. The amendment read:

Congress accepts the scientific finding of the Environmental Protection Agency that ‘warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.

This is not about whether humans are involved. This is just whether it is happening at all.

I would not mind having some scientific facts that Democrats deny. I’d prefer that deniaiism not become a partisan issue. But the GOP seems to be on a real roll here.

Here are some of the facts they are denying:

Increase in global temperatures from 3 different sets of data over last 100 years

Decrease in sea ice extent in the Arctic

.

the entire world is warming, including the oceans

Carbon dioxide levels have been on the rise

Glaciers are getting smaller

A short update

Senate Republicans to drop contempt finding against Democrats – JSOnline
[Via Journal-Sentinel]

The top GOP leader in the state Senate backtracked Tuesday, saying Republicans would lift fines and a contempt finding against Democratic senators back from Illinois – a first move toward crossing a chasm of mistrust that now divides the two parties.

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It would have been better not to have ever sent out the first email. But better late than never.

Rolling back the fines and contempt removes an issue that could keep on burning.