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Weekend Geek: Fukushima and the U.S. Nuclear Power Industry
On March 11, 2011, a magnitude 9.0 earthquake off the coast of Japan caused a tsunami that engulfed the 6-unit Fukushima Daiichi nuclear power station. Three of the six reactors (Units 1 – 3) were operating at the time, had scrammed (shut down) due to the earthquake that preceded the tsunami, and were beginning the process of cooling down.
Flood waters inundated the emergency diesel generators, rendering them inoperable, and leading eventually to a complete loss of electrical power at the station. Critical safety systems were unable to operate and supply cooling water to Units 1 – 3, leading to core damage due to decay heat, and release of radioactivity into the environment.
This event was the second-worst nuclear accident at a commercial power station in history, after the 1986 accident at Chernobyl in Ukraine. Unlike Chernobyl, a reactor vastly different in many ways from anything used in the United States or Europe and lacking any sort of containment, the Fukushima reactors were similar in design to some older reactors in use in the United States and elsewhere. So the Fukushima accident couldn’t be dismissed with a “can’t happen here” shrug. Germany reacted by shutting down all of their nuclear power stations. This was in my view an unwise overreaction.
In the US, the predictable reaction was short-term hysteria and doomsday predictions from the usual suspects until the story dropped out of the news cycle and was forgotten.
You could be forgiven for assuming that nothing has changed at US nuclear stations. But to the contrary, much has happened in response to this event; and as far as I can tell, it has not been reported. Let me discuss two important concepts:
Barriers: A typical power plant (unlike Chernobyl) has three barriers to the release of fission products into the environment. They are:
- Fuel cladding. Each fuel pellet is clad in a layer of metal, usually Zircaloy, that prevents fission products from entering the reactor coolant. A small percentage (less than 1 percent) enters anyway, but the cladding prevents massive contamination (unless it is destroyed by melting).
- Reactor vessel and related piping. These systems are designed to prevent the reactor coolant from escaping into the containment. For boiling water reactors, like the Fukushima units, this includes the steam piping to the turbine, condensate and feedwater piping, extraction steam, and heater drains, most of which is outside the containment.
- The containment building, which is designed to contain the water, steam, and heated gases resulting from a leak in the reactor vessel or connected piping inside the containment, and to control the accumulation of hydrogen gas. The containment is intended to be airtight, and capable of being pressurized to around 45 to 75 psig (this number varies depending on the type of reactor and containment).
Design Basis: This refers to the set of accidents, malfunctions, and external events (primarily earthquakes and weather) that the plant is designed to withstand. For example, to determine the design basis for a flood or a tornado, the designer would review records for the local area and find the highest flood level or strongest winds in the last 100 years, add a margin, and use that as the design basis.
One of the problems at Fukushima was that the tsunami exceeded the plant design basis, overtopping the sea wall that was intended to protect against waves up to 19 feet high. A year after Fukushima, the US Nuclear Regulatory Commission (NRC) issued an order to all nuclear station licensees requiring them to develop strategies for coping with external events beyond the design basis. They called for a three-phase approach: The initial phase requires the use of installed equipment and resources to maintain or restore core cooling, containment, and spent fuel pool cooling. The transition phase requires providing portable, on-site equipment and consumables to maintain or restore the above functions until additional resources can be obtained off-site. The final phase requires a plan to obtain sufficient off-site resources to sustain the above functions indefinitely.
Obviously, most areas in the US won’t experience a tsunami. However, there are other severe events that can challenge the operation of the station. The NRC order identified five classifications that require coping strategies beyond the original design parameters. In all, an extended loss of AC power is assumed:
- Earthquakes;
- Flooding due to external events (extreme rainfall, or rise in level of nearby lakes or rivers);
- Wind storms (hurricanes, tornadoes, etc.) and accompanying missiles (objects carried by the wind, not the weapon kind);
- Extreme snow, ice, and cold;
- Extreme heat.
Nuclear stations are already designed for these events up to an assumed design basis limit; these events are handled by built-in safety systems that start and run automatically. The NRC order concerns events that are beyond the design basis, with the normal built-in safety systems postulated to fail due to loss of AC power or other problems.
One of the biggest problems at Fukushima was that the normal safety systems weren’t working due to complete loss of power, so there were no other good, safe ways to provide cooling water to the cores and the spent fuel pools. Provisions for temporary system connections did not exist, and the station did not have portable pumping equipment, hoses, and generators on hand.
Measures taken at each power station in the US in response to the NRC order vary depending on site geography and the specific vulnerabilities identified by the licensee. Here are some measures now being taken at US nuclear stations:
- Most utilities are buying portable (trailer-mounted) diesel generators and water pumps. This equipment is being stored on-site, but at some distance (1/4 mile or more) from the main plant to guard against a single event affecting both the plant and the spare equipment.
- New, hardened buildings are being erected to store the portable equipment. These buildings feature thick concrete walls, labyrinth entrances, and no windows, and are designed to withstand earthquakes and tornado-driven missiles.
- New hose connections are being added to safety systems and to on-site water sources, so that portable pumps can be connected with hoses to provide new ways to cool the reactor core and spent fuel pool. Some stations are installing buried piping running from outside the plant to the power block, so that cooling water and diesel fuel can be pumped in from trucks outside the plant. The hose stations at the ends of these pipes are either underground or inside hardened structures.
- Several nuclear stations are installing additional barriers near doorways to guard against tornado-driven missiles. This would protect equipment that that would not ordinarily be relied upon in an emergency, but would provide a backup, manual method to assist in plant shutdown.
- Analyses are being performed at some stations to ensure that the outdoor paths relied upon to transport the portable equipment from the hardened buildings into the plant are not subject to soil liquefaction during an earthquake, which could cause sinkholes rendering paths impassible.
- Roof drainage is being studied at some plants to ensure that water can be drained off quickly enough in a heavy downpour that the accumulation does not overload the roof. Modifications are being made where necessary to provide additional roof drainage paths.
- Flooding presents more of a challenge to some plants than others. Certain plants in the Midwest, while not susceptible to a tsunami, are located close to rivers, or on a flood plain that can be inundated by a sudden, heavy rainfall. One such plant is postulating that the water level could reach up to six feet above grade in a beyond-design-basis rainfall, rendering the installed emergency diesel generators inoperable (Nobody has ever seen a flood that high, but hey, it could happen). They are obtaining a diesel generator that can be floated on a raft to provide power in this scenario. Extension piping would be installed on the existing underground diesel fuel storage tank vent to bring it above flood level, and hoses would be used to provide fuel to the floating generator. All wall and floor penetrations in the power block have been inspected to ensure they are leak-tight and resealed as necessary (They were leak-tight originally, but after a few decades of operation, seals can degrade). Upon notification that a flood is imminent, contingency plans call for sealing door openings, plugging floor drains, and installing flood barriers in pipe tunnels to keep flood waters out of the reactor building. This station has permanently installed emergency cooling water pumps in the reactor building that need only be connected to plant water systems with hoses and provided with temporary electrical power.
- All of this portable emergency equipment (other than the hose connections) is normally disconnected, and thus cannot interfere with or degrade existing installed safety systems.
The price tag for all of these measures is significant–easily in seven to eight figure territory per station. However, they will provide a lot of flexibility for nuclear station operators to respond to as- yet-unforeseen events that exceed the plant’s design bases, and manage the consequences to prevent core damage and the release of radioactivity to the environment.
Published in General
The utility owner and the Japanese government overseeing it both had sketchy records and were particularly bad about transparency so there is no public trust in either on this issue. During the crisis I ran part of our company’s response and our Japanese employees relied on our information on radiation readings and risk rather than trust their own government.
As to your other question, no, the Pacific is not being poisoned in a big way and I share BDB’s views about zerohedge.
NOW I get it.
Glad I didn’t have the TPTB exile you to Siberia.
Tom loves China, not Japan. If only we were a dictatorship led by him, the world would be wonderful.
Poisoning the Pacific? The Pacific is so huge that TEPCO could have dumped the entire plant into the Pacific with only local effects. We detonated many dozens of nuclear bombs in the Pacific ocean. We should avoid pollution, obviously, but it’s also good to avoid scaremongering hyperbole.
The Great Earthquake of 2011 was one of the ten severest in human history, *and one of the 100 most severe in the period of which geologists have any knowledge*.
Let that sink in.
Antiquated as it was, the Fukushima site performed not that badly.
It follows that the Germans are Green-pandering hysterics.
All the German nuclear freeze will do is make rich French.
I started reading Barry Brook at Brave New Climate during the Fukushima aftermath. He had a lot of deep analysis of the information coming out of the plant environment as the issue unfolded.
He’s also a big anthropomorphic climate change believer, but unlike most of the greenies, he advocates nuclear generation as the preferred alternative. In fact, the lead article on the site at the moment is a timetable for replacement of all fossil-fuel generation by nuclear in a 10-35 year timespan. (That may be the only good thing that ever came out of the “global warming” debate …)
A few points:
The tsunami killed about 15,000 people. While there’s a great deal of uncertainty, the Fukushima nuclear disaster that followed will not kill 1/10th as many.
Fukushima’s containment buildings survived the tsunami. Not protecting backup cooling generation in a similar fashion seems pretty dumb. Florida’s Turkey Point is supposedly hurricane and tornado proof. Is this true?
The German’s are dumb – and they’re now paying (3+ times US rates) for electric power.
Fukushima had a sea wall to keep flood waters from a tsunami out of the buildings; it just wasn’t high enough for the massive, 15 meter high waves caused by a powerful 9.0 earthquake.
Turkey Point would have to be hurricane proof, being located in an area where hurricanes are common. Not 100% certain whether it is tornado proof, but it wouldn’t surprise me. All US nuclear plants are designed to withstand earthquakes and high winds. The design bases usually depend on the history in the area where the plant is located. Some plants I have worked on in the Midwest are designed to withstand tornado-force winds up to 360 MPH. Not every building in the plant is designed like that, only the containments and the buildings where nuclear-safety related equipment and spent fuel are housed.
They are also designed to withstand aircraft crashing into them (this requirement predates 9/11/01). This requirement involves not only the strength of the walls; outside air dampers were modified to detect fires and close to keep burning fuel out of the buildings.
This is all a massive overreaction to an event that, it appears killed nobody. Radiation levels experienced probably will, on average, save more lives that they will take (moderate radiation doses are net health benefits).
Power plants elsewhere should not have massive spending to add more and more safety levels. On any cost-benefit analysis, the money is much better spent on other things.
Nuclear power may not be the future (in an era with practically limitless fossil fuels that require no large installations for output adjustments), but it certainly has been ridiculously over-demonized.
Several workers lost their lives in the earthquake and tsunami.
Nuclear plants are run by people from the Navy, and they follow the idea from Rickover that nuclear has to have a near spotless record to keep the hippies at bay. As for the safety cost calculation, avoiding a disaster is often worth massive amounts of money, as nuclear plants have low operating costs, but high capital costs. Losing a plant prematurely is an immense loss of profits, and cleanup is incredibly expensive.
Nuclear is great for baseload power, keeping natural gas for peaking plants that handle surges in demand. You can also use the heat for desalination. This keeps the cost of gas down. Also, nuclear is a clean improvement over coal – coal actually emits more radioactivity than nuclear.
I agree in general with your outlook, but what would you say to the argument that coal hasn’t emitted any Chernobyls?
I am not familiar with the heath benefits of moderate radiation doses. However, you are already receiving low to moderate radiation doses from cosmic rays, medical x-rays, and various other sources. What you don’t need are large, uncontrolled doses, either to the general public or to the workers responsible for dealing with the mess.
Also, although I don’t have any specific knowledge of the costs involved, I would not characterize the amount of money being spent on these modifications as “massive,” in the context of what it takes to keep a nuclear station running.
yeah, but how many coal miners die annually?
Yeahbut, this sounds like one of those flying-is-safer-than-driving arguments, or we-shouldn’t-worry-about-muslim-terrorism-because-you-have-greater-odds-of-dying-in-whatever. There’s something about mass-extinction events that makes them a lot more threatening to people than whatever they’re more likely to die from.
Risk is equal to probability times consequences. Most people don’t have a firm grasp on the probabilities of various types of accidents, but they sure understand the consequences, especially after they are reminded by an incident like the Fukushima event.
An interesting take on this is The Health Hazards of Not Going Nuclear, by the late Petr Beckman. He was the first libertarian author I read, incidentally. The vast quantities of coal that must be mined actually make the chance of accidents per kilowatt hour drastically higher than even Chernobyl-style Russian reactors, which are horribly unsafe compared to US reactors.
In all, nuclear is regulated so heavily that it is not cost competitive. Which is why virtually no new plants have been built in decades in the US.
By definition, that tells us that the regulatory costs are crippling.
Precisely my point, but exactly backward from yours.
WHAT INCIDENT?
ZERO people lost their lives to radiation. 15,000 lost their lives to the Tsunami. Fukushima is barely a footnote in the tsunami story.
Chernobyl was bad, you say? How many people died?
31. And that was with full-blown Soviet incompetence.
Compare it to chemical plant spills, daily deaths from oil rigs, basically you-name-it. Nuclear has a massively outsized reputation for danger that is not merited by the facts.
Yes, Beckmann was very good on this. I love the title of that book.
(Did you ever read his History of Pi?)
Thats because people seem unable to calculate actual risk in their lives. The most dangerous thing you do every day is step into your bathtub, followed by getting in your car…
We know at least 41 people died of Acute Radiation Sickness. The actual total is unknown, and estimates range into the thousands ( unprovable). Excess thyroid cancers number in the thousands.
However lets not forget one of the KNOWN complications was the for all intents and purposes permanently contaminated Exclusion Zone in Ukraine and Belorus. not exactly an insignificant side effect of the accident.
So we should quit freaking out about radical Islamic terrorists, right?
Another side-effect was that it helped to demoralize the Soviet Union and bring about its fall.
Realistically? Yeah.
I don’t think we know that yet. There was not much exposure to the general public, but nuclear station workers probably picked up some significant doses trying to deal with the aftermath. I agree it could have been much worse, and maybe the next time it will be.
Regardless – even if nobody died, nobody wants another Fukushima. For one thing, Units 1 – 3 are totaled. For another, if something like that were to happen here it would probably spell the end of nuclear power in the United States.
Nuclear power in the US has an outstanding safety record. Not because there are no dangers, but because utilities go to great lengths to operate safely. Continued vigilance is required to keep it that way.
If the “great lengths” are so great that Nuclear is no longer competitive, then the point is moot.
Nothing in life is safe. Death is inevitable. The question is one of comparing tradeoffs. In this respect, trying to make a perfectly safe nuclear power plant is like fixing a gall stone while the patient dies of a heart attack.
But it should not.
Look: Three Mile Island basically spelled the end of nuclear power in the US. (How many new plants were approved, built and put into service afterward? I doubt it was more than a handful).
And Three Mile Island did not kill ANYONE.
Similarly, we signed away the 4th Amendment because we had a President with too weak a character to discipline those members of the government who had the bad luck not to act on the intelligence they had before 9/11. A number of people were killed in that incident, but the measures taken were similarly disproportionate to the damage.