"All of these events feel like unnecessary disasters—if we were just a little smarter, we could have avoided them—but the fires in Lawrence are particularly tormenting in this respect. With an aircraft 35,000 feet over the ocean, you can’t simply press Pause when things don’t go right. Likewise a nuclear reactor has no safe-harbor state; even after you shut down the fission chain reaction, the core of the reactor generates enough heat to destroy itself. But Columbia Gas faced no such constraints in Lawrence. "
Pretty interesting comparison. Arguably airplanes can coast down and nuclear reactors (especially Gen-IV low-pressure ones like sodium metal or molten salt) can passively cool their nuclear decay heat post shutdown without external power. But it is true that TMI and Fukushima were not chain reacting, they were both decay heat cooling problems. For those unfamiliar with this, a chain reactor immediately drops to about 7% of full power after shutdown and then exponentially decays to 1% after a day and half a percent after weeks. Turns out 1% of a gigawatt is still a lot.
On the nuclear topic, I'm annoyed that natural gas accidents that cause deaths get way lighter media treatment than nuclear accidents like TMI that cause no deaths.
Just to be pedantic, nuclear plants generate electricity at about 33% efficiency. So to get 1000 MW of electricity, you start with about 3000 MW thermal.
HN, the place where an article using an analogy of nuclear reactors probably means that an actual nuclear reactor designer will comment on state-of-the-art nuclear reactors.
I've spent a few years in the CANDU world so it's interesting to hear opinions from elsewhere. I've grown to appreciate the lag time the design gives you.
Probably a giant radiator. Lots of equipment that is “air cooled” has an intermediary coolant that is actually cooled by air over a heat exchanger (radiator).
That's confusing. "Air cooled" usually means exactly that there is no "intermediary coolant". At the end of the day almost all equipment cools to the atmosphere after all. The difference between liquid cooled and air cooled cars/bikes is exactly that extra equipment of coolant lines and radiators versus just having airflow directly over the things you want to cool.
I wasn’t very clear, if the NaK is liquid it could flow through a radiator and could still be considered air cooled.
While there are some pure air cooled engines, lawn mowers, motor cycles, etc. A typical car engine is also considered air cooled since it gives off its heat to atmosphere even with assistance of a coolant radiator system.
Most marine engines, some power plants and some industrial equipment is considered liquid cooled since the coolant passes through a fluid to fluid heat exchanger and then that cooling water gets put back into the ocean/river. An example would be some ABB drives come in a LC liquid cooled or AC air cooled package. The motor drive lineups are the same with primary coolant going through all the drive bays the difference is at the end if they put an liquid to air or liquid to liquid heat exchanger.
> A typical car engine is also considered air cooled
We just have different definitions then. In car circles your typical car is definitely water cooled. I had never seen your definition but it also makes sense. The typical one is describing what fluid contacts the hot parts and yours is describing what mass the heat is transferred to.
My late 90s era Ducati is considered my most people to be "air cooled", but it has oil galleries that circle around the cylinder walls and an air-oil radiator. (Pedants might call it "oil cooled", but those are mostly the same people who "well actually" you when you call it a V Twin. "Well, actually, it's an _L_ Twin..." - just because it's a 90 degree V Twin rolled forward so the front cylinder is roughly horizontal and the read is mostly vertical...)
(And to further complicate matters, the 900cc two valve "air cooled" Ducati motors have those cylinder cooling oil galleries, but the 750cc motors also have oil coolers, but do not circulate the oil in the cylinder walls. The 600cc motors use the same oil galleries as the 750s, but do not come with the oil cooler...)
Airplanes coast down fine after a (double) engine failure, but they don't coast nicely when your primary instruments aren't working. The Air France flight didn't just loose airspeed indication, they got invalid readings and all associated warnings. Unfortunately that is the common failure mode for flight instruments, they don't just show nothing, they show wrong values. Fortunately pilots are trained to know how instruments work on the inside and what the most likely wrong indications and their causes are.
The problem the author points out is that you cannot "pause" to think about what information may be correct and which instruments to follow. You have to react immediately, which is much harder than considering the same decisions sitting at a desk reading the NTSB report.
If the low speed indication/alert is correct you need to push the nose forward immediately to keep the aircraft out of a stall, if the high speed indication/alert is correct you need to pull power to flight-idle and nose up carefully but immediately to avoid overspeeding the aircraft and risk structural failure.
AFAIK the Air France flight would have been ok if they had not even touched the controls. They had a lot of altitude. Of course easy to say from the arm chair.
I'm not sure how easily a regular airline overspeeds or stalls if the controls are close to a middle position. They should be aerodynamically stable (if loaded correctly).
They were initially close to a high altitude stall, the margins are not that large at that altitude, so just dropping everything isn't really an option.
The report highlighted training, which I guess is always possible to point out, but looking at the event I think they could have made more conclusions regarding how the control system performed counterintuitive by emitting stall warnings at the time they actually did the right thing, and provides little feedback when it drops into alternate law making a standard full pullback into a potentially dangerous move.
What I remember reading of the Air France flight was that both people flying understood perfectly well the situation, and had plenty of time to get out of it, but one panicked and tried to pull up even though that was exactly the wrong thing to do. The other problem was that no one else realised that one of them was trying to pull up and the plane averaged the actions of the two sticks (pull up and dive) causing effectively zero net action. (Other planes feedback each stick's action to the other so the other person would soon have realised what was going on.) They had so long to fix the problem that the captain (who had been sleeping) had time to wake up and enter the cockpit, and he finally managed to coax out the information that one of the copilots was trying to pull up, and for them to stop. By that point they were only seconds from the water and it actually was too late.
Number of deaths isn't the only metric of severity. For example, there is also the number of people who lost their homes (evacuated and not able to return for many years), which for Fukashima was apparently 150,000. [1]
Since nuclear power plants are so expensive to build, even just the loss of plant itself is in the billions.
To put it in perspective, the prediction for the number of climate refugees vary, but papers seem to put the number somewhere between 150 and 300 million by 2050.[1]
That's about one Fukushima every five to eleven days, starting from now and continuing until 2050.
To put that into perspective, about 120,000 people are displaced every day in the middle east because of a mess ultimately created in the pursuit of oil interests.
That's one Fukoshima every day.
Apparently the US felt that hundreds of thousands dead, millions displaced, and democratic governments overthrown was an acceptable price for slightly cheaper oil. I fully expect that calculation to come out the same when climate refugees are considered.
The lengths we'll go to for cheap energy and car culture, right?
Not sure why you were downvoted. You're entirely right. Oil is incredibly destructive for the environment and society, yet it's accepted because that's just how things are.
Reactors are circa gigawatt electrical. Nukes usually have a thermodynamic efficiency around 1/3rd, so a 1GWe reactor will produce 3GWt at the core. That's the heat they have to deal with when uncooled.
> On the nuclear topic, I'm annoyed that natural gas accidents that cause deaths get way lighter media treatment than nuclear accidents like TMI that cause no deaths.
Why this annoyance? I'd prefer the media for the most part shut up about energy accidents in general, considering how damaging their outcries have been for nuclear power. A few sober reports are fine. It's probably a minor miracle the natural gas industry hasn't suffered like the nuclear one.
Heh, I guess you're right: I'd prefer both nuclear and natural gas to get sober reports. I think natural gas has a better name (it's natural! As if uranium is not), no ties to superweapons, and no The Simpsons. Regular fire is just easier to understand to most folks than radioisotopes.
No, but over the past 50 years, we’ve had two severe nuclear incidents resulting in any kind of long-term environmental damage (Fukuhima and Chernobyl), and Fukushima will be remediated within a decade.
In the mean time, we’ve had Exxon Valdez, Deepwater Horizon, Andover, San Carlos, CA, plus oil trains burning down entire towns, coal mine explosions, two Gulf Wars, and sea level rise due to global warming.
Right. And the evacuation now in most of fukushima is based on old and likely very conservative dose-health relations (linear, no threshold). There is a lot of talk these days of getting a better understanding of the real risk of low dose radiation. Some people evacuated Fukushima and went to places with higher natural background and ironically got more dose
> The list of accidents is so large that the US has to create separate wikipedia pages for every 25 year span.
Actually it has a separate list page for each year since 2000. And the 25-year lists before ("List of pipeline accidents in the United States (1975–1999)" etc.) are huge lists.
I think you are only considering the damage done on land, but you severely underestimate the damage done (being done) to the ocean, which is difficult to assess though all studies I have seen so far tend to agree that anything living there is having a rough time.
I wonder how much land area has been rendered unusable from pollution by oil, coal and gas compared to nuclear. I suspect even by this measure nuclear would prove far preferable.
The difference is many tens of thousands of smaller sites affected by fossil fuel pollution and accidents as compared to a couple of large incidents.
Other kinds of consequences like cost of mitigation, value of lost property (and lost value of property what wasn't destroyed by itself - you can easily see thousands of homes near, but not in evacuation zone deprecating severely), costs of health checks for hundreds of thousands of people etc. - are worse in nuclear accidents.
Fans of the nuclear industry doesn't like to columnize the costs of 'externalities'.
For one, they rarely mention the amount of US government subsidies ($hundreds of billions) poured into getting the early plants up and running. For another, the unwillingness of insurers to take an interest in those operations.
When Rocky Flats spilled a little Pu dust into the Denver suburbs, they just raised the 'safe' exposure by a factor of 10. Easy peasy.
Pretty interesting comparison. Arguably airplanes can coast down and nuclear reactors (especially Gen-IV low-pressure ones like sodium metal or molten salt) can passively cool their nuclear decay heat post shutdown without external power. But it is true that TMI and Fukushima were not chain reacting, they were both decay heat cooling problems. For those unfamiliar with this, a chain reactor immediately drops to about 7% of full power after shutdown and then exponentially decays to 1% after a day and half a percent after weeks. Turns out 1% of a gigawatt is still a lot.
On the nuclear topic, I'm annoyed that natural gas accidents that cause deaths get way lighter media treatment than nuclear accidents like TMI that cause no deaths.