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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
Just a note as I’ve not read this yet – but could you re-edit this to put in paragraph spacing? Would make it easier to read.
Sorry, first I import the text and publish it, then go back and clean up the resulting mess. I haven’t figured out a better way yet. I didn’t know anybody would start reading it so fast, especially in the middle of the night.
Insomnia is a harsh mistress. I will definitely read this!
Excellent article – as a someone who has studied nuclear energy, as well as other energy sources, this is dead on.
Interesting. Thank you.
and yes,
The reactors as Fukushima functioned well despite being hit by an earthquake and tsunami in excess of the design expectations.
What the reactors could not survive was the flamingly inept and dishonest mismanagement of the emergency.
We need to open the permanent storage facility for our nuclear waste, or develop a Breeder reactor program to recycle the usable material. The current status quo, with waste piling up in permanent “temporary” storage facilites really increases the risk during an accident. The Japanese were idiots for placing their spent fuel pools on top of the reactors. It magnified the damage caused by the meltdowns, and subsequent hydrogen explosions many fold. The Progressives and Greens use safety as their number one weapon against Nuclear Power, then do everything they can to prevent a solution that would mitigate an accident.
I’ll clarify a bit — of course, the placement of generators and spent fuel rods, and electrical requirements in order to control the otherwise no-power emergency systems, and so forth… these were all fiasco-grade foul-ups.
But the actual nuclear disaster portion of this was mismanagement in real-time. If not for several bone-headed (and frequently dishonest) decisions made in the course of handling the crisis, this would merely have been expensive. This was defeat snatched from the jaws of victory. You have to work pretty hard to goon up something as robust as a nuclear reactor in as spectacular a fashion as they did, but they did it.
Perseverance.
Thorium pebble bed reactors are the future. This is like the only central planning project the morons in D.C. should be doing.
Very interesting!
Being an aesthete — personally, I like the smiley faces on the cooling towers. That’s the story here. Photoshop is a fantastic tool.
Whoever 1) conceived of doing this and 2) got the shadowing just right has my undying gratitude (and un-stifleable mirth) forever.
Absolutely. The fact we are still using 1950’s technology is a crime.
Advanced photoshop: Set the yellow to a garish bright hue, then ramp the transparency up. The shading was already there, just waiting to be taken advantage of :-)
There they go again, criminalizing everything in sight.
Photoshop’s not even that old. Cretin.
I think it was anonymous or on one of his posts that it was pointed out how the threat of lawsuits keeps the US reactors stuck in older technology because if they change things, lawyers will jump in and say: “so you did know this improvement could be made. Why didn’t you do this before.” Literally the best is the enemy of the good.
The comparison was made about Cessna having a similar problem (at least about improvement made at the factory, the deep pockets) — they can’t improve their designs without those changes being used against them in the court cases.
My husband is involved in the procurement engineering of parts for plant-wide upgrades for several plants based on beefed-up design coming out of the lessons learned at Fukushima. The plants are going back and ensuring that necessary systems and components needed for safe shutdown or restart will work even beyond design basis events under conditions like what happened in Japan. It’s an ongoing process of review that seems quite thorough, and utilities have a mandate to do it.
I worked at nuke plants for many years and know the redundancy built into the systems and procedures. This latest effort creates another layer upon multiple layers to ensure no accident of any magnitude happens here–even if Homer Simpson is sitting in the control room.
Is anyone blown away by the reality that the Japanese, the Japanese! let Fukishima happen? I mean, aren’t they the Smart Ones who do technology, and everything better than us (even if they’re interested in kinky sex, but not interested in having children or a future..)? Does Fukishima confuse Thomas Friedman?
Also, I keep seeing posts (on the admittedly sketchy blog Zerohedge) reporting that the Pacific is still being poisoned by Fukishima in a big way. True?
Very nearly.
Thank you for this post. I’ve wondered what has been the US response to Fukushima.
Great article. thanks for taking the time.
There is a fabulous book on this subject (and solar, wind, geothermal, etc) by William Tucker called Terrestrial Energy. For non science types (like me) it does a great job of laying out the positives and negatives of different energy sources, and the clear #1 is nuclear, with solar being #2. He goes to great effort to explain how the whole “long term storage” question is essentially a red herring, and that nations like France recycle their spent fuel rods (to Kozak’s point), making widespread storage unnecessary. .
Why this idea doesn’t have more traction simply boggles my mind. Another self inflicted problem.
And I’ve stopped going to zerohedge. I don’t buy their excuses for the continuing Jew-hatred over there. They could clean up if they wanted to. They don’t want to.
Do you mean in the comments section or the whole thing?
After long enough, I no longer make a distinction.
???????????
I was going to call it a sin, but didn’t want to offend any atheists here.
Lots of the posts by Tyler Durden are flat out antisemitism.
Misfired joke. back to the drawing board.
I got it.
I like to joke that nuclear power is the only energy source safe enough to be run by Homer Simpson.
This is not helped by the extensive approval process – you need to go through a long and involved public comment period and NRC review just for the location, then another permitting process to operate, and you are exposed to activists shutting you down at any point. It’s like the FDA review of drugs – it prioritizes safety over efficiency.
I look at the nuclear field like I look at the GOP primary – lots of good options