What Ever Happened to 3 Mile Island? - 42 years later 

Its funny how Three Mile Island is one of the three big nuclear accidents people always think of, along with Fukushima and Chernobyl. But the Windscale fire in the UK had arguably more serious radioactive release than Three Mile Island. It wasn't a civilian power plant like the others, but it is interesting that its been so forgotten about

As a former commercial reactor operator a few things are missing. The relief valve indication was only an indication of power, not an indication of the actual valve position. At the time the secondary side auxiliary feed water system had undergone maintenance but had failed to be properly restored.

I had a long career as a reliability engineer in the oil industry. Sometimes I helped with other industries. Every single project that I analyzed had problems, some minor some so serious that the project got cancelled or totally redesigned. I am talking multi million and billion dollar projects. Finding the problems was the easy part; sometimes ridiculously easy. I could give examples but would likely be sued. Some companies, typically the Norwegian ones, immediately welcomed the information and always resolved the issues. Some UK and US company managers however I can only describe as going berserk, but they all had to back down. It is easy to imagine from even the simpler explanation of what happened at Three Mile Island that the designers had not thought through the system fully. They could have made a design that was less likely to fail. You can't eliminate or predict all failures. But what you can do is put in systems that mitigate the impact of failures. It isn't difficult and it is way cheaper than leaving faults to cause problems. The most genius idea about safety was in the Cullen report on Piper Alpha. The Safety Case is a brilliant system. Sadly it is not adopted globally and at least while I was in the US it wasn't adopted there.

I served in US Navy Nuclear power 1984-90. Our procedures and Instrumentation were updated directly by lessons learned at TMI. The incident report(s) were required reading.

I actually think the 3 Mile Island incident was a good thing. It was a very low danger accident and lots of valuable knowledge was gained by the industry like flaws in current designs & procedures to ultimately make sure less people die due to nuclear power... By having a partial meltdown.

I was in 8th grade English class when the principal came on the intercom saying there was an emergency and the busses were already outside ready to take us home. We were about 45 min or so from the TMI plant. It was about 2 weeks i think that my school district was closed.

I was 29 years old and my Company Belfab made the incore detection sensors that were inserted into the nuclear core . I welded the sensor ends and made large steam valves to control the pressure at a stable level . What happened was several incore temperature detectors failed to detect a temperature increase and the core started to overheat . My steam valve assemblies could not let off all the extra pressure and the core split open and blew out radiated steam . I remember that night QA and the lead Inspector stayed at Belfab all night to make sure all inspection signatures were written on the documents !

My mother-in-law was a nuclear chemist at TMI at the time of the Unit #2 accident. I remember talking with her about TMI unit 1 vs. unit 2. She described unit 1 as an excellent reactor that performed exactly as it was designed, from the time it first was put into service all the way through its service life. Unit #2, not so much.

I've heard TMI described as a "spectacular non-event". Invaluable for the resulting improvements in safety, but the event itself has acquired a reputation far in excess of its actual danger.

The real lesson of TMI: operators can never have Too Much Information.

I was at Redland High School about 4 miles from TMI on the day of the accident. It was one of the reasons I became a medical physicist. Excellent video.

If Homer had brought donuts that morning everything would've been fine.

TMI 1 could still be operating today after a refurbishment and still go strong for another 40 years. However, nukers run best in multiples of 2 for best economic efficiency especially around downtime for refuelling. This would catch TMI 1 out. But even after two Level 7s and one Level 6 nukers are still the safest and most reliable form of low carbon power generation we have. With TMI 2 it was a major lesson around design (cooling circuits and control room layouts, and even regulation as the NRC got a major overhaul after this. Then President Carter had served in the Nuclear Navy so knew his stuff when the accident occurred. Not the first time Carter would bail out a nuker either (Canada was another).

I was too young at the time to remember the incident but grew up in a nearby part of Pennsylvania and got to hear a lot from those old enough at the time about what they recall. Of particular note was a bad PR move by a Met-Ed spokesman who angrily snapped at a reporter's question about a reported release of radiation. The report, which later turned out to be false, had come in after the press conference began so the spokesman had not been briefed, but his angry response at the question didn't do anything to help the public opinion of the operator and the incident.

We should be thankful Three Mile Island was built with a strong containment building, and the reactor was a pressurized water reactor that did not have a positive void coefficient and the "tip effect" the reactor that exploded at Chernobyl had.

I was young then and I remember a guy coming to the house and was talking to my mom and dad about stocks. They sort of planned on buying consumer energy stock which paid 7.55 while GPU as recall paid 8.25%. They went with GPU. Not long after the 3 mile island incident occurred. The dividends top and I remember the stock they paid $7,000 for went as low as $17. The stock will be split between the kids at TOD, but as of about 10-15 years ago it started doing very well and it has split a few times, although the utility company has been bought and sold several times and dividends every month are back.

Nuclear plants are safer today than back then.

It was good to revisit this incident. It was a big thing at the time and turned a lot of people off nuclear power.

Fantastic video! These mini-documentaries on engineering accidents are invaluable, as they help ensure future safety by highlighting in clear detail what went wrong. Please make more videos similar to this one; bridges, power plants, the Challenger, etc.

Great video my guy! Keep up the great work!

I grew up only a few miles away but I wasn't born until a few years after the accident. Seeing the island and the steam climb into the air on a calm day was a normal thing growing up. As a kid in the 90's we went to TMI on a field trip and I got to stand inside the base of one of Unit 2's empty cooling towers. Pretty amazing site to see as a kid.

That was the best explanation of biochar I've ever heard, keep it up

We just had a hell of a fire here in Colorado, talk about relative sponsorship! We're all stoked for more content Droid Boi. Thank you for your high quality stuff

Healthy new year wishes to you and the company you keep, Paul! :)

Still live nearby. Toured it twice. My father in law worked at TMI for decades. My brother worked at TMI until the Covid shutdown, now he works from home but still for the same company, for other plants. Shame TMI got shut down. Terribly short sighted by our PA legislature, and also partially caused by subsidies to wind/solar causing them to be ridiculously cheap, natural gas being extremely inexpensive, and nuclear trying to fit in. Funny how not long after TMI shut down, suddenly the price of natural gas and LP fuel seems to be creeping up. Suddenly nuclear has become financially viable again. Unfortunately, these plants can't just "turn back on". Once they are off - they are off. Wont even be until after 2075 until the plant begins its final clean up and deconstruction.

damn, Americans really go the extra three miles when it's time to viral market their movie releases.

I know part of the public fear was because a movie about a nuclear meltdown was released a couple weeks before this incident. I decided to watch the movie. It’s CRAZY how the initial failure and subsequent improper response is so similar…..

this is the first video in months to appear on my youtube... ive been subbed and have notifs on for years

TMI resulted in zero deaths, but is often called the "worst nuclear accident in US history". Why is that? The SL-1 accident, for example, killed three people directly, yet a lot of people have never heard of it, and there have been other nasty accidents as well. TMI was very public and very scary (I was living not too far from it at the time as a child and it was BIG news), but in the end turned out to be little more than an expensive mess.

I grew up in Lancaster, PA which is about 30 miles away from TMI. On the first day of the accident it was one of the first nice weather days of the spring but we were not allowed to play outside due to the gas releases. On the night of the accident my parents had our bags packed and we were ready to evacuate. I took care of a neighbor's dog when they did decide to temporarily evacuate.

Love the channel. Keep it up!

There used to be a outdoor concert venue located in the river below Three Mile Island. We were setting up an Atlanta Rhythm Section show when we were told we needed to leave on that day 42 years ago.!

The fukushima "nuclear" disaster was overblown by media... nobody died because of the nuclear power plant (only after the government decided it would be a good idea to evacuate hospitals because of the "nuclear threat") and then there was a bunch of water pumped into the pacific, but that hardly raises radioactivity above background levels... and that was after the plant has literally been hit by a very strong earthquake and a freaking tsunami...

My dad worked for ConEd for 40+ years and started as a reactor engineer at Indian Point. He always described Three Mile Island as the worst case scenario for a reactor "meltdown" in the US.

As ever great informative video and well presented and explained. Thank you.

Love your videos =)

At time of 3 mile I was Enginner in Royal Canadian Air Force. As member of Refrigeration Electro- mechanical section on a heavy Radar station of NORAD we followed 3 mile islands closely. Heavy radar deals with radiation and similar cooling & back up systems. Right away from diagrams shown we determined 2 thing A lack of training & emergence practice drills. Not knowing where gauges are and use of go/no go should have had a few responsible above the operators hung publicly by the scrotum! Than you all these yrs later for confirming what usas young airmen deducted long ago! PER ADRA AD ASTRA - through adversity to the stars

I think the amazing thing that the average person didn't know that the other Unit was still operating for decades after the accident. I mistakenly (until very recently even) thought that 3-mile island area was a radioactive no-man's land. Additionally, there were 0 deaths as a result of the accident....just a very very expensive clean up on isle 2.

Thank you for the video you have done 2021 keep up the good work you're doing Happy New Year

Great video, Paul...👍👍

I never even look to see what the title is. If it’s a curious droid video I click on it. I think this and technology connections are the only two channels like that. You’ve been on fire this year. Your proximity fuse video was a masterpiece, As with so many more this year that I could literally name in order each buy each. I’ve watched all of them so many times! Keep it up and here’s to a wonderful new year of content at least!

I lived in York, PA for a few years and it was creepy living near it

So refreshing to see a video that isn’t full of nonsense about the Nuclear issue. Nice job.

Great explaination. Always excellent, informative videos.

What about talking more about more advanced fission reactors? We got stuck on light water reactors and never really got fission right. Fusion is a whole different story, but I think the fission story is the worst told of them and so needs more Cherenkov light shown on it.

After the Three Mile Island (TMI) incident, all the reactors of the same type (world-wide) had to be retrofitted with technical systems that would prevent the accident from happening again. At that time, I was part of the team that built the largest and most modern nuclear powerplant in Switzerland and I was tasked with designing and building two systems that would ensure the same TMI accident could not happen there as well. The final operating approval for the entire plant was (among other things) contingent upon these two systems being built, tested and then licensed by the regulator. One of the systems was called the "Post Accident Sampling System" (or PASS) and it would allow to safely take highly radioactively contaminated water and air samples from outside the containment at various elevations of the reactor after a potential accident. As a result of the TMI accident, today EVERY nuclear powerplant still operating has a Post Accident Sampling System, as well as a few others that were invented after the TMI accident.

Love your videos Paul! Can't wait to see you turn pro and get your own Discovery Channel show!

Thanks Paul. I was 15 when this happened and it was very scary to live through

You’re absolutely right. We’ll need safe clean reliable nuclear power in the future. They should have already been built next to the coal fired plants and replaced them. Thanks for the honest report about what actually happened and the zero health risk to the public. Can you do another about Fukushima?

Great video, as usual Paul! That was very clear and concise information delivered in truly professional way. Keep up the good work!

As usual - superb and very professional explanation !!! Very good !!!

Great post Paul. brain food as always. Happy new year to you and your love ones 🙏

Born a year before Chernobyl. To the day. About 30 miles away. Thankfully we were fairly “well off”, in as much as you can be in the Soviet Ukraine. So we were able to get uncontaminated food. And then escape in 1991. A month before my mom died of cancer. Was it Chernobyl? Or the crummy “free healthcare?” Will never know.

So many people don't understand just how particularly and uniquely more destructive Chernobyl was compared to the other nuclear accidents. It was a completely different system and failed in a way reactors now, and most at the time, could not.

This was informative, thank you.

I'm pleased to find a view which explains the Three Mile Island incident. Great job, well done.

As someone who sees TMI nearly everyday, It is a real shame that it was closed.

Nuclear is as safe as many other forms of energy, we will go back to it someday.

Three Mile Island was so over-hyped it's sad.

I live in the town in the shadow of three mile island - Goldsboro PA. It’s always interesting hearing about my little corner of the world as a result of this one incident

Rather than a back-up to so-called "renewables", nuclear should be our primary choice for baseload generation. All we have to do in order to get it right is to follow France's example, as far as policy goes, and seriously develop safe and cheap nuclear options, such as, e.g. LFTR. Even though it would be nice to have, thermonuclear fusion is still way far down our future. As for windmills and PV panels, if we look closely at their external costs and remove various form of subsidies, they no longer look so appealing, while they are always unreliable and a burden to electricity grid planning and construction.

Sad that this reduced the building of new reactors. Nuclear needs to be part of our energy strategy more than it has been.

In college, because of my background in computer science and physics, I had the opportunity to intern at Argonne National Laboratory, where I was assigned to Dunn and Schleger's TMI investigation project. The objective of the project was to determine why the TMI accident released far less radiation than expected. I wrote data analysis software and had a couple of opportunities to run the experiment. It was a great experience. Needless to say, the scientists studying the accident continued to be quite comfortable with nuclear power after the accident, unlike the panicky reaction by the media and public.

I dont live to far from there, but I'm not old enough to remember it happening. Thank you for the video!

Good too see your shirts are still radioactive 😆 keep them coming

Well Done Paul! Your right, Chernobyl is another story that will haunt this planet forever! Happy New Year!

Once again a great vídeo :) also love the outfit, always on point 😎

You make great videos man thank you for your content. Especially this it's close to home because I live like an hour away from here in PA.I've been there and camped out there it's totally safe.

The fear around nuclear power is like fearing all electronics because of an exposed live wire somewhere in the world

And because nuclear power was seen as so "dangerous", the modern world just keeps getting dirtier and closer to the brink. Thank you eighties public! Truly the best years...

Great video. Best I've seen on Tree Mile Island. Thanks. Top Notch.

Hello from Middletown, PA!

Really excellent presentation. You're un-biased from a position of empiricism, something the BBC needs to learn. To them any crackpot opinion is equally viable.

I remember watching The China Syndrome, it's a great movie, love me some Jack Lemon. Days after the movie as you noted, a very similar event actually happened at TMI. I suspect time travel may be involved. 🙂

Really enjoyed the video fantastic explanation. I was no more than 2 weeks old when this happened less than 20 miles away from the plant. Every Time March came around they would talk about this on the news the anniversary it actually caused me to be very curious about nuclear energy and anything nuclear related. I'm so glad that it didn't explode or I wouldn't be here. 💥🤯

Three mile island. Hits home for me. Grew up down the road from it. Also my grandpap worked there.

I worked in operations at Ontario Hydro just after this happened. ALL the valves of consequence and especially those inside containment all had limit switches that independently verified a valves position. If a relief valve had not seated correctly, especially one as important as this one, the operators would have seen the indication almost immediately. As it was explained to me, you have a sensor that indicates a PHT over pressure and turns on a light on the panel. Independent of this, the PRV which is largely regulated by a large spring (in those days) is supposed to actuate at the same pressure, but the light and the valve are NOT connected. Now, for a small less critical system where you want to save a few bucks on instrumentation sure, but for a nuclear reactor. No way. It is the same kind of mistake like Fukushima where the safety systems were on the ground floor and sure to be flooded how does this happen? In addition, we were told that the operators at TMI were trained to run the panel and other folks work in the plant on inspection routines and such like. Not so where I worked, you had to work in the 'field' for at a minimum 6 years before even being allowed to be trained for the panel and then the exam was pretty tough. You never got any feedback only pass or fail and you were only allowed to write it 3 times in your life. I am not a fan of PWR reactors. Something about loading a reactor vessel up with slightly enriched fuel and then poisoning it to keep the reaction under control is unsettling. I really liked the system we have/had in Ontario where we fueled on power and had some reactors running at 96% availability at that time. In 1986 a pressure tube split on Pickering #2 and caused a serious loss of coolant, but everything was contained by the safety systems, the reactor was retubed (as were many others) and put back in service. I am pretty proud of that. This was all run by the government and while it cost more to set up, I think it has paid benefits for many years in higher operational availability and safe operation. I am not comfortable allowing for profit companies run nuclear power stations. I think the risk is too high. I do not know who pushed who in Japan, but one does hear that the companies in Japan have a lot of influence. However, having the safety systems where they were located in a tsunami region is criminal, but as JFK once said “victory has a 100 fathers and defeat is an orphan..” Any technology, nuclear, air travel, rail, sea travel and so on can kill many people when not operated in faith with the principles of physics. Such principles often run counter to someone's financial plan. Such unscientific influence can never be responsibly allowed in such situations where failure of a system or of the people operating it leads to catastrophe. If regulations are 'job killers' they are there because unregulated systems are 'people killers'. I guess on voting day you get to choose.

This is probably one of the best descriptions of the accident (in layman's terms), I've seen, ever. As an aside - do you have links to the various footage, and reports that were shown in the video? I keep a folder of TMI-related stuff. Thanks!

That brought back memories. I wasn't even old enough to attend school yet, and I remember when that happened. I grew-up about 60 miles away from 3 Mile Island.

Paulk, what a simple but clear explanation of what happened to 3-mile island with useful contrasts to Fucashima and Chernobyl. Great video with amazing photos and vid included.

I've watched China Syndrome a few years ago, because I was curious how anti-nuclear it is really. I was surprised that it isn't at all. But it isn't really pro-nuclear either. Somehow it manages to objectively show both sides of the argument. And the story isn't really about the reactor, it's a relatively standard plot, and could have worked with any industry. The nuclear reactor was just a relevant, exciting, and a bit mysterious, setting for the movie. It only became the center of the movie after TMI happened.

In the early 90's I started working with a team in college who were doing nuclear power plant fault monitoring with neural networks. It was just barely possible with the computers we had back then, and we had to spend a lot of time optimizing the code. We also worked with other industrial plant monitoring for quality prediction, and saved the companies a lot of money by modeling their plants so they could figure out how to tune them for differing weather conditions, etc. If the plant produced bad product, it'd have to be recycled, which was very expensive. So my personal carbon footprint is OK, having helped save quite a lot of energy and other resources, starting back then. I'm still interested in the Wren thing though, seems like they have good plans.

Very interesting, thank you

This was a very well done video, Thank you for taking the time to get all this information together for the video.

Thank you for telling the *truth* which is that 3 Mile Island didn't do any lasting major harms and that nuclear power is safer than all other forms of electric generation, even wind. Okay, you missed that last part, but you at least gave us facts instead of fear. That's why I stay subbed to this channel!

I actually live in Middletown pa. It’s the town where the island is. I’m also a tmi baby. Meaning I was born the year the meltdown accrued.

Freat Content as always!!!!! Thank you for the facts

You Rock Paul!

This should be interesting. 👀 I live very close to TMI.

Man, @CuriousDroid, why do we keep JUST missing each other on projects? I flew a drone over HAARP like a week after your video on it, and I shot a TON of drone video of TMI not long ago but lacked the narrative ability to really make something of it. Please let me know if any missile silos or weird abandoned Cold War places are on your To-Do list, so we can compare notes! :D

2:30 biochar is all well and good for fertilizing gardens and farms, but that removes that vegetable matter from the forests. We'll eventually have no forests because there isn't enough nutrients in the ground for new trees. Why not put the biochar back in the forest? It does the same thing, but the company won't be able to sell anything.

Zircalloy, being a hydrogen source during a high-temperature excursion is probably the worst material to use for fuel cladding. The industry should have immediately sought alternatives.

Nuclear power is safe and profitable. Big fan of Terra Power. Great video! Hope to see more.

I'd argue the ban on Plutonium or Mox fuel which can be reprocessed in breeder reactors (like the rest of the entire world does) - causing the nuclear waste handling and storage issues power plants now have did more than anything to taint the nuclear power industry. We could drastically reduce if not virtually remove that problem switching to Mox. In fact, the largest power station in the US (Palo Verde, in AZ with 3 cores) was designed for Mox - but had its fuel replaced with Uranium after the ban. Thanks to environmentalists - the US is the only country with nuclear waste 'problem'. So, thanks for that.

Thank you

4:05 The problem is not so much that after the reactor scrams itself the core is "still very very hot", but that it still produces decay heat, which is why if you scram it and then fail to cool it sufficiently it will heat up more and eventually melt. I feel like that is kind of important to understand. If it was just very very hot but not producing more heat after a scram, it would just cool down more slowly and never melt.

Compared to Chernobyl and Fukushima, we got very lucky with Three Mile Island.

Great video! If only the media was as thorough and fact-oriented as this channel during those days, maybe we wouldn't have seen the start of the nonsensical and baseless fearmongering we see today regarding nuclear power. It's extra moronic nowadays as we move away from pressurized water cooled reactors and towards even safer and more efficient ones, such as the Liquid Flouride Thorium Reactor and other generation 4 designs.

Interesting shot of working men in the 1970s @ 9:55. Everyone had lotsa hair, people were smoking inside, nobody was fat and nobody had tattoos.

Your youtube-channel is really extremely pleasant, interesting topics well presented. We are very greatful out here! Greetings from Finland! Here our brand new NPP (Olkiluoto 3) just started up (10 years after schedule). Hoping for the the best, fearing the worst.