Saturday, March 12, 2011

Cringely Explains the Reactor Problem in Japan

I've read the news but nothing really explained why there is a long drawn-out problem with cooling the reactors in Japan. Here's the first intelligent discussion I've read. It is the indomitable, irrepressible, wonderfully smart all-around tech reporter, Robert X. Cringely to fill the information gap:
There’s a 40 year-old nuclear reactor cooling-down right now in Japan following the big earthquake in that country. Actually there are 11 such reactors cooling-down, automatically brought offline by the 8.9 temblor, but one of those reactors at the Fukushima Daiichi generating plant is not going gracefully and 3000 people have been moved from their homes as a precaution.

Good idea.

I worked as an investigator for the Presidential Commission on the Accident at Three Mile Island, 32 years ago, and a few months studying the plumbing TMI’s Unit 2, which is actually younger than the errant Japanese reactor, gives me a very healthy respect for the danger in Japan.

That Japanese reactor shut down automatically within seconds of the earthquake, the idea being that dropping the thermal load (stopping the nuclear reaction and cooling-down the reactor) would minimize risk overall from a huge plumbing system that was likely compromised and vulnerable. Radiation and the passage of time conspire to make pipes brittle and aftershocks make brittle pipes break. Not good.

The 10 other reactors behaved as expected, but this unit didn’t. Once the reactor was no longer making steam to drive a turbine and generate electricity the plant was supposed to fire-up diesel generators to make the power needed to keep coolant pumps running. Only the diesels wouldn’t start. It can take up to seven days, you see, to get such a reactor down to where it can survive without circulating coolant. With the diesels out (under water perhaps?) the plant relied on batteries to run the pumps — batteries good for only eight hours.

Tokyo Electric Power Company isn’t saying much. Utilities tend not to and Japanese utilities are notoriously secretive. But we got a clue to what’s happening from U. S. Secretary of State Hillary Clinton, of all people, who remarked that the U. S. military was delivering “coolant” to the stricken reactor.

“Coolant?” wondered aloud all the CNN and Fox News nuclear experts looking for a lede for their stories. “What is she talking about, coolant?” This is a boiling water reactor and the coolant is water. The U. S. Air Force isn’t needed to export water to Japan.

This shows the limits of cable news experts and maybe experts in general, because Hillary isn’t the kind of person to choose the wrong words. She said “coolant” and she meant “coolant.” Though she may not have known she was saying so, she also meant the reactor was dead and will never be restarted.

A boiling water reactor does just what it sounds like — it boils water to make steam that drives a turbine generator. This is as opposed to a pressurized water reactor that uses the nuclear reaction to heat a coolant that never really boils because it is under high pressure, then sends that coolant through a heat exchanger which heats water to make steam to drive the generator. Boiling water reactors are simpler, cheaper, but generally aren’t made anymore because they are perceived as being less safe. That’s because the exotic coolant in the pressurized water reactor can contain boric acid which absorbs neutrons and can help (or totally) control the nuclear reaction. You can’t use boric acid or any other soluble boron-laced neutron absorbers in a boiling water reactor because doing so would contaminate both the cooling system and the environment.

That’s why the experts didn’t expect it because they are still thinking of how the plant can be saved, but it can’t be.

Though the boiling water reactor has already been turned off by inserting neutron-absorbing control rods all the way into the core, adding boric acid or, more likely, sodium polyborate would turn the reactor off-er — more off than off — which could come in really handy in the event of a subsequent coolant loss, which reportedly has already happened. But that’s a $1 billion kill switch that most experts wouldn’t think to pull.

I’m guessing the US Navy delivered a load of sodium polyborate from some nuclear aircraft carrier reactor supply room in the Pacific Fleet. Its use indicates that the nuclear threat is even worse than presently being portrayed in the news. Tokyo Electric Power Company has probably given-up any hope of keeping those cooling pumps on after the batteries fail. Eventually they’ll vent the now boron-laced coolant to the atmosphere to keep containment pressures under control.

Sodium polyborate, by the way, is something you might use around the house, since it is the active ingredient in most flea and tick treatments.

An earthquake with such loss of life is bad enough, but Japan has also just lost 20 percent of its electric generating capacity. And I’ll go out on a limb here and predict that none of those 11 reactors will re-enter service again, they’ve been so compromised.
I love Cringely's stuff. He's a stick-it-in-your-face honest reporter willing to go out on a limb and make predictions. He isn't always right, but he's always well informed and you learn stuff even when he is wrong. He's my kind of tech reporter. Somebody well worth reading.

Update 2011mar13: The NY Times is reporting that things are still getting worse and the problems are spreading to other reactors:
Japanese officials struggled on Sunday to contain a widening nuclear crisis in the aftermath of a devastating earthquake and tsunami, saying they presumed that partial meltdowns had occurred at two crippled reactors and that they were bracing for a second explosion, even as they faced serious cooling problems at four more reactors.

The emergency appeared to be the worst involving a nuclear plant since the Chernobyl disaster 25 years ago. The developments at two separate nuclear plants prompted the evacuation of more than 200,000 people. Japanese officials said they had also ordered up the largest mobilization of their Self-Defense Forces since World War II to assist in the relief effort.


Then on Sunday, cooling failed at a second reactor — No. 3 — and core melting was presumed at both, said the top government spokesman, Chief Cabinet Secretary Yukio Edano. An explosion could also rock the No. 3 reactor, Mr. Edano warned, because of a buildup of hydrogen within the reactor.

“The possibility that hydrogen is building up in the upper parts of the reactor building cannot be denied. There is a possibility of a hydrogen explosion,” Mr. Edano said. He stressed that as in the No. 1 unit, the reactor’s steel containment would withstand the explosion.


Officials also said they would release steam and inject water into a third reactor at the Fukushima Daiichi plant after temperatures rose and water levels fell around the fuel rods.

Cooling had failed at three reactors at a nuclear complex nearby, Fukushima Daini, although he said conditions there were considered less dire for now.


The Japanese Nuclear and Industrial Safety Agency said that as many as 160 people may have been exposed to radiation around the plant, and Japanese news media said that three workers at the facility were suffering from full-on radiation sickness.

Even before the explosion on Saturday, officials said they had detected radioactive cesium, which is created when uranium fuel is split, an indication that some of the nuclear fuel in the reactor was already damaged.


Worries about the safety of the two plants worsened on Saturday because executives of the company that runs them, Tokyo Electric Power, and government officials gave confusing accounts of the location and causes of the dramatic midday explosion and the damage it caused.


The decision to flood the reactor core with corrosive seawater, experts said, was an indication that Tokyo Electric Power and Japanese authorities had probably decided to scrap the plant. “This plant is almost 40 years old, and now it’s over for that place,” said Olli Heinonen, the former chief inspector for the I.A.E.A., and now a visiting scholar at Harvard.

Update 2011mar13: Here is the title from a Scientific American article that goes into the details of what else can go wrong at these Japanese reactors:
Nuclear Experts Explain Worst-Case Scenario at Fukushima Power Plant

The type of accident occurring now in Japan derives from a loss of offsite AC power and then a subsequent failure of emergency power on site. Engineers there are racing to restore AC power to prevent a core meltdown.
There is now a 4th reactor that is melting down. From a NY Times report:
Japanese officials struggled on Sunday to contain a quickly escalating nuclear crisis in the aftermath of a devastating earthquake and tsunami, saying they presumed that partial meltdowns had occurred at two crippled reactors, and that they were bracing for a second explosion, even as problems were reported at two more nuclear plants.

That brings the total number of troubled plants to four, including one that is about 75 miles north of Tokyo.

The emergency at the hardest hit plant, Fukushima Daiichi Nuclear Power Station, appeared to be the worst involving a nuclear plant since the Chernobyl disaster 25 years ago, and at least 22 residents near the plant showed signs of radiation exposure, according to local officials. The crisis at that plant, which is much further from Tokyo, continued late Sunday.


Until late Sunday, the government had declared an emergency at only two nuclear plants, Daiichi and the nearby Daini.

Then, the International Atomic Energy Agency announced that Japan had added a third to the list because radiation had been detected outside the plant, which is about 60 miles from Sendai, a city of 1 million people in Japan’s northeast. The government did not immediately confirm the report from the I.A.E.A., which said it was not yet clear what caused the release of radiation.

Soon after that announcement, Kyodo News reported that a plant about 75 miles north of Tokyo was having cooling system problems.
Update 2011mar15: Since this original post things have gone worse than expected at the reactors and now there is a radiation leak. To get some perspective on that, here are some numbers from physcist Lubos Motl:
... 3 Sv is what causes a 50% of death within a month if untreated. Below 1 Sv, you won't see any "guaranteed" short-term impact. But don't forget that ionizing radiation is unhealthy for the life of an individual at any amount.

If you don't want to remember too many numbers, just remember that a few sieverts are already on the sure path to death. Imagine that one death is equivalent to 5 Sv. So the figures with the units of one sievert, when divided by 5, approximately give you the probability of death as a consequence of the ionizing radiation.

So "a few millisieverts" mean something like one permille probability of death. The most typical equivalent dose you get from the natural background at a generic place of the Earth is 2.4 millisievert per year. Because I defined the death to be 5 Sv, 2.4 millisievert (per year) is the 0.05% probability of death caused by the radiation (per year).

You see that the lifetime from the background radiation is comparable to 2,000 years. Because the human life expectancy is around 70 years, it follows that about 1/30 of the deaths should be due to cancer from the background radiation - which is therefore about 1/10 of the total number of cancer cases because about 1/3 of people may be dying of cancer.
According to this NY Times article, the radiation leakage rate is just under 1 millisievert per hour. This is equivalent to 8760 millisievarts/year. That is significantly above the background 2.4 millisievarts/year. This is definitely not a healthy area to be in, but it won't kill you outright. Evacuation will work. They really need to come up with a solution to contain the radiation leakage!

Lubos Motl is saying that the leakage rate is 400 millisievats/hour which is 400 times worse that the number in the NY Times article from March 14. That takes the exposure up to rates that can be leathal in roughly half a day's exposure! That is very serious. The leakage needs to be contained.

Lubos Motl ends up with some sobering numbers:
If you spend twelve hours by playing in the vicinity of the worst reactor of the Fukushima power plant, you will probably die. And if you die, who will continue to fight against the meltdown threats? Between the reactor buildings 2 and 3, the equivalent dose is 0.03 Sievert per hour. That will give you 150 hours of life over there - unless you are protected in some way.

Of course, it's much more important what the radiation levels will be in the nearby large towns - and I don't even want to use the word Tokyo in this paragraph. But be sure that if the radiation level in Tokyo or another city managed to jump to something like a millisievert per hour, or even per day (and it would be sustained for a day), that would mean that 1/5,000 of the population of the city would ultimately die as a consequence of the exposure during the hour (except for those who would manage to die earlier because of another reason) unless they were successfully kept indoors all the time.


Just to end up with some relatively good news: a millisievert per hour is (so far?) insanely far in Tokyo. They measured 0.8 microsieverts per hour. I defined one death per person to be 5 Sv, so 0.8 microsieverts per hour means 0.16 ppm (parts per million) death per person and per hour. Multiply it by 37 million people in the Tokyo metro area and you get 6 deaths in the city per hour (or 150 deaths per day or so, if the radiation remains elevated). That's nonzero but won't be measurable statistically and will remain hugely smaller than the casualties of other lethal threats.

There are a series of bulletins and notices on reactor status from the damaged sites at the Japan Atomic Industrial Forum. Here is the status of Fukushima as of 8:00 March 16. This appears to be providing timely and accurate data.

Click to Enlarge

From Geoffrey Styles's blog Energy Outlook, here is a bit of information about the loss of power and other energy-related issues with post-quake Japan:
The impact on the Japanese power grid extends beyond the shutdown of 9,702 MW of nuclear power capacity, including 2,812 MW at Fukushima Daiichi that will not resume operations for many years, if ever. Some fossil fuel power plants have also shut down, and more than a fourth of the country's refining capacity is down, cutting off a significant supply of power plant fuel oil, along with a wide range of other petroleum products. That helps explain the interest in light, sweet Indonesian crude that can be burned directly in power plants as a replacement for low-sulfur fuel oil. Significant quantities of Indonesian Minas crude formerly came to the US west coast for a similar purpose, when we still had a lot of oil-fired power generation, although the crude was normally processed to remove the valuable light products from the fuel oil before sale to utilities. (My first job in the industry was at a refinery that did just that as part of a contract Texaco had with a southern California utility.)

Burning crude oil for power is a practical stop-gap, and as long as so many of Japan's refineries remain shut for damage assessment and repair, it shouldn't have much impact on the global crude market, since the crude those refineries would have otherwise run is now surplus. That explains the $5 per barrel drop in crude prices this week. However, if demand recovers faster than Japanese refinery capacity returns to operation, much of that extra crude oil will need to be processed in refineries elsewhere around the Asia-Pacific region, to provide the refined product imports that Japan will need.

Update 2011mar17: Here is a very nice description of the situation at the reactors by a physicist in a Discover magazine blog. Here's a bit from the very end where he tries to imagine the worst possible scenario:
The worst-case scenario for the Daiichi reactors plays out something like this: 1. the storage pool at #4 is indeed dry. Because it’s uncontained, the radiation levels in the area get very high. Everyone needs to evacuate the complex. 2. Without anyone manning the cooling systems, the cooling stops. Everything overheats. 3. There are various explosions, resulting in a breach to a containment vessel. 4. There is a subsequent steam explosion, and a plume of radioactive material is generated. 5. Wind carries the plume in the direction of Tokyo (world’s largest metropolis), a mere 140 miles (225 km) away. We can’t even contemplate trying to evacuate and treat a city of 35 million people. As far as I can tell, things do not appear to be headed in this direction. But such an outcome is unfortunately not outside the realm of possibility, and just contemplating this should freak you out. But, to reiterate, it’s very unlikely, and a lot of things would have to go catastrophically wrong. I’d love to quantify just how unlikely, but cannot. My guess is that nobody can, since there are too many uncertainties, and we’re fundamentally in uncharted territory.

Update 2011nov04: IEEE Spectrum has a detailed analysis of the first 24 hours of the Fukushima disaster:
Millions of people had to die on highways, for example, before governments forced auto companies to get serious about safety in the 1980s. But with nuclear power, learning by disaster has never really been an option. Or so it seemed, until officials found themselves grappling with the world's third major accident at a nuclear plant. On 11 March, a tidal wave set in motion a sequence of events that led to meltdowns in three reactors at the Fukushima Dai-ichi power station, 250 kilometers northeast of Tokyo.

Unlike the Three Mile Island accident in 1979 and Chernobyl in 1986, the chain of failures that led to disaster at Fukushima was caused by an extreme event. It was precisely the kind of occurrence that nuclear-plant designers strive to anticipate in their blueprints and emergency-response officials try to envision in their plans. The struggle to control the stricken plant, with its remarkable heroism, improvisational genius, and heartbreaking failure, will keep the experts busy for years to come. And in the end the calamity will undoubtedly improve nuclear plant design.

True, the antinuclear forces will find plenty in the Fukushima saga to bolster their arguments. The interlocked and cascading chain of mishaps seems to be a textbook validation of the "normal accidents" hypothesis developed by Charles Perrow after Three Mile Island. Perrow, a Yale University sociologist, identified the nuclear power plant as the canonical tightly coupled system, in which the occasional catastrophic failure is inevitable.

On the other hand, close study of the disaster's first 24 hours, before the cascade of failures carried reactor 1 beyond any hope of salvation, reveals clear inflection points where minor differences would have prevented events from spiraling out of control. Some of these are astonishingly simple: If the emergency generators had been installed on upper floors rather than in basements, for example, the disaster would have stopped before it began. And if workers had been able to vent gases in reactor 1 sooner, the rest of the plant's destruction might well have been averted.

The world's three major nuclear accidents had very different causes, but they have one important thing in common: In each case, the company or government agency in charge withheld critical information from the public. And in the absence of information, the panicked public began to associate all nuclear power with horror and radiation nightmares.

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