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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
I agree with almost everything you are saying, but unfortunately it’s not the world we live in. TMI didn’t kill anyone, but Unit 2 is totaled. If you keep totaling cars, you have to learn to drive more safely. If you have not killed anyone, you are probably just lucky.
Anything can kill you. I don’t see why power plants are not treated as consumables like houses or cars or airplanes. All of these have accidents, sometimes fatal. But nobody pretends they should have a 100% safety record.
You might be safer driving a bulldozer than a Camry. Shall we mandate that people have to drive earth movers instead?
No. We have already mandated that the Camry must have seat belts, air bags, tires with more than 1/16″ tread, a tire air pressure monitoring system, 2.5mph bumpers, headlights and taillights of a certain size and brightness, center high-mounted stop lamps, etc. etc. etc.
Sure. But people are still dying in them! We must make them perfectly safe, at all costs!!!
This is precisely the same logic that has killed the US nuclear power industry.
I understand and agree with most of your sentiments. However, I have to work within the regulatory regime we have. The reality is, the public is not going to accept any significant reduction in nuclear safety, and if it kills the the nuclear power industry [which is NOT dead yet, BTW], they don’t care. So we do the best we can within those constraints to keep nuclear stations operating safely in the most cost-effective manner possible.
Blue State Blues thank you for your post. I am also in the nuclear power industry, but on the designer / OEM side and not on the individual plant / utility side. As you state, both sides are involved in a massive undertaking to increase the defense in depth strategies and equipment to ensure our plants can be properly cooled and kept in a safe condition in all manner of circumstances far beyond what was considered in the original designs. These changes allow operators and emergency responders to cope with all sorts of situations until the external emergency (floods, earthquakes, hurricanes, etc.) are long over and everyone else returns to normal, so that the plants can then be de-fueled safely, inspected for damage, and returned to service if possible. These types of changes significantly reduce the already very low chances of danger to the public, danger to the plant staff, or even danger to the plant equipment itself by giving greater flexibility to the plant operators
Unlike what has been repeated here a couple times, we in the US currently have 4 brand new modern Westinghouse AP1000 plants being built (2 in Georgia at Vogtle and 2 in South Carolina at VC Summer) and a fifth older generation plant being completed in Tennessee at Watts Bar. These plants will also be equipped with the flexibility plans and equipment to deal with these beyond-design-basis scenarios just like the existing plants, while also bringing more than 5,500 megawatts of stable electricity production to their power grids since nuclear power plants provide a higher capacity factor than any other form of power production. (Capacity factor = (actual megawatt-hour rating) / (maximum possible megawatt-hour rating) )
Now that GE’s ESBWR plant has also received its NRC design certification, utilities that would prefer to operate a GE BWR (boiling water reactor) instead of a Westinghouse PWR (pressurized water reactor), can now move further forward to build these in the US too. Although other new nuclear power plant builds seem to be at a standstill for the time being, I think we will see even more of these built even as newer styles of nuclear power plants are designed, tested, and certified for use.
We all can agree that nuclear FUEL costs are low.
33% in the US for nuclear.
78-88% for others.
The rest is overhead.
Natural gas and oil kill more people than Nuclear. Far more. So why the regulatory overhead?
Rationally, Nuclear should provide the bulk of US power. It does not. I ascribe this directly to the perception problem and the resulting regulation.
I understand that if you work in the industry, there is no choice but to work within the constraints. My beef is not with that mindset, but with the constraints themselves.
Really, it is not that dissimilar from desalinization plants in California: extremely hard to build, 2-4X the cost of the same plant in Israel, and many many more years to get through the hoops. And desalinating water is a complete no-brainer. Unless, of course, one WANTS people to be punished for existing and/or circumventing Mother Nature. Which is why liberals are the key supporters for regulating both cheap power and water.
The inability of the US to do rationale “Power Infrastructure” is a direct result of having the world’s highest per capita ratio of lawyers…. behind only Greece. Does anyone else see a less than positive comparison to Greece? We can always scare ourselves into a national paralytic stupor given enough safety studies and legal activism.
While Shakespeare admonition to “first let’s kill the lawyers” is terribly out of context here, but given the spate of recent articles on NRO about the out of control prosecutorial system in large sections of the US, perhaps something short of that is due for our survival as a great nation.
Three Mile Island was not the end of nuclear – it was the slow economic growth and overbuilding in the seventies that killed the demand for nuclear plants.
I think you have a point. I don’t think they are any less safety conscious in France or South Korea, yet they don’t have the costs we do.
Credit where credit is due: The NRC has streamlined the licensing process. In the past they would issue a construction permit, then when a plant was constructed they would issue a low-power license so that testing could proceed, then after testing was complete, an operating license. Each step had its own complicated, lengthy, expensive application process and inspection regime. Licensees would spend billions to construct the plant, not knowing for certain if or when they would receive an operating license. The current process is to issue a single “combined license” which is issued when the design phase is complete, and allows both construction and operation.
If nuclear could produce power at competitive prices, there is always demand to build new plants. It is like oil: if you can produce it for $10 a barrel, you can sell all you can pump.
Between 1978 and 2012, no new nuclear reactors were approved in the US. Three Mile Island was in 1979. Do you really think there was no causality? I was raised on anti-nuclear propaganda, and all of it referenced Three Mile Island.
The This Week in Nuclear podcast took a look at the new nuclear plant orders and showed that it fell before TMI. TMI was certainly a problem for the nuclear industry, but their response was actually beneficial to nuclear operations. Capacity factors on nuclear plants are much higher than the 70’s and the industry has the best process safety of any industry. Oil refineries keep on exploding, but nuclear has become incredibly safe.
This is my key point. The cost of “incredibly safe” has strangled the nuclear power industry. Just as forcing people to drive battle tanks instead of econoboxes would make them safer, but cost so much that people would resort to pogo sticks.
Because of the “incredibly safe” ethos of nuclear, MORE people are dying – because the market turns to oil refineries that are less safe.
So the unintended consequence of such high safety standards is that more people will die!!!
There was likely some causality to the lack of orders after the TMI-2 incident, but electrical power demand dwindled and various plants that were already under construction at the time were abandoned as a result. Perry Unit 2, Washington Public Power Units 2, 3, and 4, Watts Bar Unit 2, Palo Verde Units 4 through 7 or 10, Harris Units 2 – 4 and others were all left incomplete because of the collapse of electrical power demand. Some plants like Watts Bar 2 (now being completed), Perry Unit 2, and a couple of the Washington Public Power units were well under way and closer to being finished than started when they were halted.
It’s worth it if it saves even one child’s life! No cost is too great, even if the cost is thousands of lives. Only a cruel, callous Republican would deny that to our children.
More seriously, I am told kids of my generation grew up to be afraid of nuclear holocaust, which I suppose is true, but I grew up learning to be afraid of the midnight knock on the door. My mother explained that reality to me when I was 4 or 5, perhaps while Stalin’s body was growing cold, or more likely the year after. She made the point that someday it could happen here, too. (She didn’t warn about the current rash of no-knock raids and asset forfeiture, though.) Her conversation didn’t induce any nightmares that I remember – I had probably heard stuff like that in conversations around me, and kids are pretty resilient. But that was the background for how I learned to think about government when I became politically aware.
So this nuclear topic makes me wonder, wouldn’t it be a great idea to take as many safety measures in harnessing governmental power as we rightly do when harnessing nuclear power?
I understand your point. Several nuclear proponents that I have read make a similar case.
However, nuclear plants benefit from process safety because they are cheap to run, but expensive to build. Most western-style reactor accidents are total losses of the unit, even when no one dies. If the reactor is totaled, that’s an immense loss of revenue. One of the sayings in process safety is “If you think safety is expensive, try an accident.”
Oil demand is driven by use of gasoline and diesel fuel, not by electric power. Coal and gas are nuclear’s competitors in power generation.
I just want to go on record here and now that I’m against this idea and that, if this comes about from a law, I want an exception for me to be able to use a Segway instead. I mean the bouncing will really be hard on my back. (I know that you will counter with the fact that my back wouldn’t be so bad if I had already been using pogo sticks but it’s too late for me to change now.)
I think something like 6 people were killed building the Aria casino/hotel in Vegas. Just sayin’
CuriousKevmo
I think something like 6 people were killed building the Aria casino/hotel in Vegas. Just sayin’
That’s a pretty bad safety record, actually. You shouldn’t get killed just for going to work.
No I shouldn’t think so. Unless, you know, you work for the Army or Marines.
The world is an unsafe place. Many car accidents happen going to and from work. Most trucking accidents happen “in” the workplace.
Or to put it another way: many more people in the world die because they do not have access to inexpensive energy, than would die in the operation of nuclear power stations that have low safety standards.
Unlike nuclear safety, industrial safety doesn’t cost that much. Accidents are much more costly.
Yup. Only considering the monetary value of losing a plant, you’re looking at a $6 billion to $8 billion replacement construction cost per new unit. That of course completely neglects the costs associated with the unplanned purchase of replacement power for the contracted power the lost unit was supposed to provide; insurability; cleanup; decommissioning; and many increased regulatory burdens assuming a utility who cooked their plant could even qualify to build a replacement nuclear unit.
I’m very late in replying to this post, but I still want to thank you for providing an excellent rundown. I’m glad to see an appropriate response by the U.S. to this disaster.