25th Anniversary Of Three Mile Island

fbform writes "March 28, 2004 is the 25th anniversary of the Loss Of Coolant Accident (LOCA) at the nuclear power plant on Three Mile Island, Pennsylvania. It's a good time to reflect on the impact it has had on our nuclear safety policy and interface design in general."

Re:Fusion

[AlecC]

Sure - when it happens. And yes, Iter is the next step on the way, and will show the technical possibility of fusion with net energy output. But it is a long, long way from showing the commercial feasability. It is going to be a long time before we have fusion power - and it is always possible that we will discover some barrier which means it will never be commercially feasible.

too bad they stopped building them...

[DangerSteel]

I remember reading about nuclear power plants that were in the middle of construction when TMI happened. And then the projects went dead. Uneducated people were scared to let the plants be continued, ( in my best Hank Hill voice ) and those damn hippies needed to get jobs, and that's partly why we are way behind in providing power today. Witness events like the brownouts in California and the big power outage last year in the northeast U.S.

What surprises me...

[James A. M. Joyce]

...is seeing how the fuck these accidents actually happen. Both Chernobyl and TMI seem to be based on a ridiculous chain of events fuelled by unfortunate coincidence, fallible mensuration equipment and human idiocy.

For instance, at TMI, there was a massive chain of events going like this (I'm taking this from the Wikipedia article). If any of these steps were omitted an accident never would've happened:

1. "The plant's main feedwater pumps in the secondary non-nuclear cooling system failed at about 4:00 a.m. on March 28, 1979"
2. "This failure was due to either a mechanical or electrical failure and prevented the steam generators from removing heat."
3. "First the turbine, then the nuclear reactor automatically shut down. Immediately, the pressure in the primary system (the nuclear portion of the plant) began to increase."
4. "to prevent that pressure from becoming excessive, the pressurizer relief valve (a valve located at the top of the pressurizer) opened."
5. "The valve should have closed when the pressure decreased by a certain amount, but it did not. Signals available to the operator failed to show that the valve was still open. As a result, the stuck-open valve caused the pressure to continue to decrease in the system."
6. "Meanwhile, another problem appeared elsewhere in the plant. The emergency feedwater system (backup to main feedwater) was tested 42 hours prior to the accident. As part of the test, a valve is closed and then reopened at the end of the test. But this time, through either an administrative or human error, the valve was not reopened -- preventing the emergency feedwater system from functioning."
7. "As the system pressure in the primary system continued to decrease, voids (areas where no water is present) began to form in portions of the system other than the pressurizer."
8. "Because of these voids, the water in the system was redistributed and the pressurizer became full of water."
9. "The level indicator, which tells the operator the amount of coolant capable of heat removal, incorrectly indicated the system was full of water."
10. "Thus, the operator stopped adding water. He was unaware that, because of the stuck valve, the indicator could, and in this instance did, provide false readings."

And so on and so forth. This is terrific shit. Seeing how many stages the thing went through just makes me glad this happened somewhere other than the decomposing USSR. With better engineering of measurement tools the whole thing would never have happened.

Re:Shame

[Anonymous Coward]

The thing which I can not fathom about the American nuclear power policy is that they are encouraged to make HUGE reactors. (Had to look this up for nuclear physics class at one point) The US Navy has an almost perfect record with identical, small reactors. I conject that the safety part of the equation has been figured out. I persistantly wonder why it's a bad thing not to just use the design from a submarine and just put 12 of them in a row, all of the same design, and man them with ex-Navy personnel.

At this point, I'd put a dog on a treadmill generator to not have coal power though...or an ignorance-rutting politician. ;P

--degs at 68k dot org

Gotta call mom

[Triv]

My mother used to work for General Public Utilities (the company that owned TMI) and was at the plant during the accident - it's probably the cause of my glowing personality. (rimshot).

In all seriousness, if anybody has any questions they'd like me to pass on I'd be more than willing to. I'll post the answers here or in a JE or somewhere.

Triv

Re:Shame

[coastwalker]

There has to be a continious re-evaluation of all potential sources of power whilst our fossil fuel reserves are being depleted. It is perhaps better that we discover the potentials and the pitfalls of nuclear power before the situation arises where there is no choice but to use nuclear power. We do now at least have the knowledge to advise the growing Chinese economy on the safest way to utilise it for example should they find the need for power outstrips the availability of fossil fuel.

Energy policy has a big impact on the environment if global warming is directly linked to the burning of fossil fuel. Nuclear power may ironicaly have a lower impact on the environment in the long term if we solve the problem of waste recycling. Radioactive materials are dug out of the ground so it does not seem impossible to put them safely back into the ground. Exhaustion of fossil fuel will automatically drive greater use of water wind and wave power but only policy will drive the use of technologically sophisticated power sources like fusion and nuclear power.

Re:Shame

[john.r.strohm]

The truth is that modern techniques could probably make nuclear power an extremely safe alternative.

What do you mean "could"?

In terms of lives lost, damage done, or just about any other measure you care to name, provided you restrict yourself to a competent design, nuclear fission is ALREADY the safest power generation technology known to man. Read "The Health Hazards of NOT Going Nuclear" by Dr. Petr Beckmann.

The key phrase in that sentence is "competent design." One of the key parameters in any nuclear reactor design is the void coefficient, and, most particularly, the sign of the void coefficient.

From http://www.nrc.gov/reading-rm/basic-ref/glossary/v oid-coefficient-of-reactivity.html "Void coefficient of reactivity: A rate of change in the reactivity of a water reactor system resulting from a formation of steam bubbles as the power level and temperature increase."

From http://www.disenchanted.com/dis/lookup.html?node=1 748 "The 'voids' refer to pockets of steam forming in the reactor core, and a reactor is said to have a positive void coefficient if an increase in voids leads to an increase in reactor power. A reactor with a negative void coefficient is one which will see a decrease in reactor power as pockets of steam increase."

Briefly, if a reactor is designed with a positive void coefficient, it will inherently have a risk of a Chernobyl-style thermal runaway. If a reactor is designed with a negative void coefficient, it will not have that particular hazard. This fact was known to the Soviet reactor designers, who designed the RBMK reactor at Chernobyl (among other places), and was also known the US designers who wrote the US standards for reactor design. Positive void coefficient designs are flat-out illegal in the United States.

To do the safety analysis, you have to take, for example, black lung deaths of coal miners into account, and supertanker oil spill environmental damage. You also have to take into account the number of people who will, while attempting to install solar water heating panels on their roofs, will slip, fall, and break their necks.

If you want to prattle about radiation hazards, bear in mind that every lump of coal you burn, every drop of oil, every cubic foot of natural gas, contains some amount of radioactive carbon-14, and the ash (and emitted CO2) is thus radioactive waste. Ditto for wood. (Wood smoke contains other nasty things.)

Re:Gotta call mom

[csirac]

I've never really studied this incident, so here are my questions probably already answered out there..

Not trying to blame the operator or anything - but what level of understanding/theory did they have?

Were they aware that it was possible for the water level indicator to give incorrect readings?

Was there any "manual" way for an operator to casually check (sanity check) proper functioning if they suspected a fault, or would that have required additional personell/procedures?

I guess being in the 1970s, there would not be anywhere near the number of sensors possible these days.. but surely these valves would have been wired up to the monitoring station?

- Paul

Re:You evil man!!!

[plugger]

Except that the natural material is purified to increase the proportion of U235. Also, I never heard of radioactive iodine or calcium occurring naturally in the environment. There lies the danger, radioactive isotopes of compounds which are stored by the body.

Toured TMI

[arachnia]

I used to work in the radiation safety field and went on a technical tour of TMI just before the change in owners (current owner is AmerGen).

We were able to visit some aspects of the non-functioning side - the cooling towers (I have photos I took while standing inside one [uiuc.edu], and here's another [uiuc.edu]), the empty turbine room, and the control room.

Surprisingly standing around the skeletons of the non-functioning cooling towers wasn't nearly as strange as comparing the turbine rooms between the functioning and non-functioning sides of the plant.

Anyone who has seen a turbine room in any kind of large power plant knows how huge they are. The turbine room used for the functioning reactor was hot, noisy, and full of intimidatingly large equipment. The huge emptiness of the unused turbine room was just plain strange in comparison.

IMNSHO, the worst thing about the TMI accident was the lack of communication both inside and outside of the plant. We can only hope that we've learned from our mistakes.

Re:Your ignorance is a shame.

[Trurl's Machine]

Nuclear Power is perfectly safe when done right, and it's done right in the US. The worst that could happen in the US in an accident condition is that parts of the power plant are destroyed. nd for even that to happen, so many very closely watched things would have to go wrong that it's basically not going to happen.

The Twin Towers were also perfectly safe buildings that could never collapse. Not on their own, anyway. But we are living now in a totally different century. The one in which modern technology can be helpless against a small group of fanatics capable of orchestrating suicide bomb attacks. Nuclear power used to be perfectly safe when done right - but it was in the last century. Now any US or European nuclear plant is actually nothing but a huge "KICK ME!" for the Al Quaedda boys. If I was you, I'd me more careful with your "basically not goint to happen".

Re:Viability of LSLT nuclear energy?

[Almost-Retired]

Your analogy regarding the incoming vs whats in the bank falls slightly short.

The incoming also creates a small amount of 'heavy water' in the oceans. The creation process I've been told is forever as long as the sun shines, and has long ago, as in billions of years, reached an equalibrium point. If a reactor could be designed to make use of this, it would only take a lead pencil sized stream of this heavy water to power every currently fossil fueled device on the planet. In simpler terms, we have enough in the bank, drawing interest, the interest being more than sufficient to power mankinds sometimes evil schemes.

Extracting that quantity from the seawater would not, even over millions of years, materially effect the concentration balance of this isotope in the seawater.

The one item I can't drag up from memory is the byproducts of its fusion. About the only thing that I recall is that its output would be steam, aka water, and some apparentlly benign gas, probably hydrogen, but I'll let the real experts testify on that point.

The real trick is that this isn't fission, its fusion. Relatively much more difficult to achieve in that most of the tokamak type devices built so have not made break even in power output. OTOH, data on such research seems to have gone underground in the last 10 years.

Maybe its time some of the people playing with this gave us a progress report?

Cheers, Gene

Seabrook evacuation plans

[Rich Klein]

I vaguely remember a controversy from a decade or so ago. I think Sununu was governor of New Hampshire at the time. The Seabrook nuclear power plant in Seabrook, New Hampshire is about 40 miles from Boston, and is in a very popular summer vacation spot (adjacent to Hampton and Salisbury Beaches). Traffic in the summer is, as you might expect, very heavy with beach-goers. New Hampshire settled on an evacuation plan for the power plant that, in many people's minds, ignored the reality of traffic jams in the area. It also ignored those living on the other side of the nearby Massachusetts border. Many in Massachusetts called for a postponement in operation of the plant until a more acceptable evacuation plan was released, but, IIRC, New Hampshire said, in effect, "you're not the boss of us" and went ahead and put Seabrook into service. I don't remember the evacuation plan ever being modified after that.

If anyone can remember events better than I can, please speak up!

Containment for graphite-moderated reactors to big

[Anonymous Coward]

TMI was a pressurized-water reactor. These are also water-moderated. I.e., fast neutrons from fission are slowed to thermal speeds so they can cause more fission reactions by the water in the core.

Chernobyl was a graphite-moderated reactor, which means that the fast neutrons were slowed by bouncing off the carbon atoms.

An interesting thing about water is that it has two effects in fission reactors:

1. It acts as a moderator (bouncing neutrons off the hydrogen atoms of water molecules is one of the best ways to slow a neutron down).

2. Water also acts as a poison to the chain reaction. The hydrogen atoms do have an affinity to sucking up neutrons and turning themselves into deuterium and tritium. This effect causes the fission chain reaction to peter out.

Which effect predominates depends on the physical geometry of the core and the layout of fuel, water, control rods, graphite, whatever else is in the core.

At TMI the moderation effect of water predominated, at Chernobyl the poison effect.

This means that at Chernobyl the primary coolant acted as a poison to the chain reaction - so remove the coolant and the nuclear reactions run amok - not an explosion, but all kinds of bad stuff. And that "bad stuff" includes, IIRC, a phase transformation of the graphite at a really high temperature that releases a lot of energy.

Conversely, at TMI when the core lost its coolant fission stopped and only decay heat from the radioactive decay of fission products remained - more than an order of magnitude less than rated reactor peak power depending on power history of the reactor (i.e., if the reactor has been running at 100% power for a few weeks, decay heat production is maxed at about 7% of full power, and decays rapidly)

But the loss of coolant at Chernobyl and resultant runaway nuclear reactions caused a steam explosion of the remaining coolant in the core that severed all emergency coolant connections into the core (and kill everyone in the reactor building itself, IIRC). This steam explosion probably would not have breached any containment vessel, but the later energy release from the graphite and the fires almost certainly would have anyway.

And Chernobyl was all caused by dumbasses shutting down the reactor protective systems designed to prevent them from running the reactor in such a condition. Chernobyl had safety features to prevent operation in the range where the disaster that happened would be possible (which was actually highly dependent on power history since the radioactive fission products also have a huge effect on fission in the core [ iodine-136, IIRC]), but since the engineers had a test they just had to perform even though the reactor hadn't been shutdown for a few days like it was supposed to be, they simply shut down the system that was designed to prevent the reactor from going kaboom.

Re:Nuclear power industry not safe.

[prandal]

No, it is not safe. Remember "we almost lost Detroit" and all the other near-catastrophes, including one that involved a nuclear plant that actually had a basketball covered in duct tape stuffed in a vent.

The one I "liked" Was the incident at Brown's Ferry involving a candle [antenna.nl].

Scary!

Re:Stop and pause

[phillymjs]

...this should make some of us pause and think about what could have been...

Indeed. I was only 5 when TMI happened, and while I don't remember hearing about it from my parents back then, I do remember hearing about it in 1986, when news reports of Chernobyl got them talking about the TMI incident and how worried they were in '79. Thanks to the west-to-east weather patterns, a meltdown at TMI would very probably have affected Philadelphia, 90 miles away. It would definitely have obliterated the state government, as Harrisburg is only 10 miles from the plant. I've had to go to Harrisburg a few times on business, and you can see the TMI cooling towers from the Turnpike. Even 20+ years later, the sight of them made me shudder a little.

If you want to see one author's take on what might have been, there's an old sci-fi novel called "In the Drift," [amazon.com] set in an alternate Philadelphia of ~2079-- 100 years after the meltdown at Three Mile Island.

If you'd rather stay with this reality, PBS put out an interesting documentary on TMI. [pbs.org]

~Philly

Blah.

[bj8rn]

The Titanic was also supposed to have been perfectly safe, even practically indestructible. And yet all it took was a single iceberg. The moral being that nothing is "perfectly safe".

Now, as for nuclear plants: do you really think noone has ever considered the possibility of an attempt to blow up a nuclear plant? Well, maybe noone has and they really have been completely unguarded until recently, but I don't buy it. I'm quite sure they were possible targets for Soviet saboteurs; surely the US and European governments thought of this. And yet they still built those plants. Why would the current situation be any different?

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[account_deleted]

Comment removed based on user account deletion

Live near by it.

[BoxOfCuriosity]

My wife and I live a few miles from the reactor. I lived here during the accident. I still feel a little stange when I drive by it. Unfounded but its in the back of my mind. and no the streets do not glow. I used to know one person who able to look directly out the window at it. (accross the street riverside. They did move out for a bit durring the accident. Can't say I blame them. I figure in some ways it is probably the most watched reactor in the us now. They can't screw up... Heh.

I live..

[raindown]

Approx. four miles (line of sight) from the nuclear power plant in Limerick, PA and not a day goes by where I worry something is going to happen, and it's not a very serious worry.. more like "hm, what if something happened right now?".. then I ponder for 30 seconds and go about my business. On the first Monday of every month at 2pm they test the alarms and it's one of the most disturbing, interesting sounds I've heard. It's a normal siren, but since there are quite a few of them going off at once you can hear the phase differences and it's pretty eerie, especially when you forget that they do this test. Oh well, it's quite a beautiful sight to see a lot of the time and at least I have my potassium iodide tablet waiting on my desk if anything does happen.

Re:Shame

[Ironsides]

Actually, most people running nuclear reactors ARE ex-Navy personel. After they serve there years in the Navy, they are EXTREMELY employable at the power plants due to their level of training and experience. And these guys probably get at least $100k per year at a reactor plant, more that double what they get in the Navy when they retire.

The clear truth about nuclear energy.

[Anonymous Coward]

"The trush is that nuclear power is already the safest and cleanest power source in the USA"

The safety is quite debatable, with all the near disasters from incompetance that did not happen only due to luck. The "cleanest" is undebatable: it is far and away the dirtiest. If you don't believe me, why not store some nuclear waste under your bed. Myself, I'd store coal dust. A lot less nasty.

"The truth is, the movement against nuclear power has far more to do with OPEC financing than concern for safety, liabilities"

It has everything to do with safety, and a lot to do with cost (the things are so expensive). The movement for it has huge corporate interests (energy companies) that you forget about.

They tried to build one in my state several years ago. A lot of it was public (taxpayer) funded. After the cost overruns were 3 times what the power company said it would cost, the government finally pulled the plug. It was really just a form of corporate welfare.

"The sad truth is that we could all have had clean, cheap, safe, and environmentally friendly power a long time ago"

We would not have had it with nuclear, since it is the dirtiest, it is super expensive, and it is dangerous. Environmentally friendly? That is a joke.

Re:Shame

[Beryllium Sphere(tm)]

>But there is still the waste disposal problem.

It's very poisonous but there's not that much of it. As long as the dangers are less than the dangers of other technologies and less than the dangers of not having electricity then fission is the prudent choice.

Incidentally, mercury is toxic forever and coal plants are disposing of it in people's lungs.

We were lucky

[forgetful]

The critical issue about Three Mile Island is not what didn't happen, but what almost happened because NOBODY HAD PLANNED for what almost happened. If the TMI reactor had not just been re-fueled, it likely would have blown the containment vessel and produced a Chernobyl-class disaster. Remember the "hydrogen bubble?" Know where that hydrogen came from? It came out of the interstices in the various metal components when the protons from the reaction had joined up with electrons to produce hydrogen. Normally, the hydrogen stays trapped and doesn't cause a problem, but if the materials melt, that hydrogen is freed and it boils out. Because the fuel rods were new, the pressure within the containment vessel "only" went to about 1000 psi. If the rods had been older, so they contained vastly more trapped hydrogen, the hydrogen could have blown the vessel before anybody knew what happened. After several days the operators got a special dispensation to vent the radioactively contaminated hydrogen and steam into the atmosphere. Better we take the little dose than risk the big one! The crucial point is that a response had to be worked out after the fact, because there was no plan in place that anticipated the escape of the hydrogen from the core meltdown. Similarly, had the core melted totally, rather than just almost totally (there was some water left in the bottom which prevented total meltdown), all those plugs in the bottom of the containment structures where cables come through could have melted out. Then you could have had TONS of molten uranium and debris under enormous pressure squirting into the environment. We were lucky at Three Mile Island. That is not to criticize the people that handled the failure. This is just a statement that no technology can anticipate every eventuality, and arrogance leads to disaster, as witness: both Shuttle losses, the collapse of Teton Dam, many terror attacks, etc., etc. I am not rabidly anti-nuke, but nuke electricity will never be "too cheap to meter" as was promised at the outset. I know too well the political, economic, technological, and social realities. Sixty years into the nuclear era, the U.S. still does not have a permanent repository for nuclear waste. I still think the best use for the 1000 tons of plutonium on Earth would be to shoot it into space, in the engines of spacecraft bound for Mars, the asteroids, Jupiter, Saturn...

Re:Shame

[Anonymous Coward]

And by the way, most nuclear power plants ARE run by ex-Navy personnel.

Including TMI at the time of the accident. Seriously.

Re:Nuclear power industry not safe.

[Artifakt]

"some of the other costs of coal are usually not counted for nuclear, such as mining."

And Vice Versa - Possible deaths from truck-car accidents involving trucks transporting nuclear fuel have routinely been included in estimates of the risks from nuclear power, while being omitted from coal.

Re:Shame

[Artifakt]

Carbon 14 is something that needs to be taken more seriously than it generally is. C 14 decays to nitrogen, so its stable decay endpoint is chemically different. How much chance is there of a single C 14 atom's cauasing a mutation if it decays inside a living creature? The answer is frequently treated as not a lot, compared to the stuff we've been calling really dangerous, like Plutonium, right?
Wrong. Since the DNA molecule has a carbon based backbone, the chance of a C 14 decay causing a mutation is 100%, IF that particular C 14 is in a DNA molecule (and in trillions of your and my cells, it is). Unless you can raise an organism on food containing only isotopically purified Carbon 12 sources from conception, there's not much can be done about this.

Re:Your ignorance is a shame.

[dasdrewid]

Well, I'm glad then that I live in Houston, where we're perfectly safe from terrorist attacks. We don't have any of that damn nuclear crap! (Well, actually we do, but only a small one...) Nah, we've got good old oil. Petroleum refineries, oil wells, oil tankers (naval and road going), oil tanks, Liquid Natural Gas tankers and terminals, etc. So yeah, we don't have to worry about terrorists wanting to take a crack at us...

Not that we need terrorists. We have enough industrial accidents spilling tons of toxic chemicals into the air as it is. It's kinda sad when it's no longer surprising to turn on the news and see a column of smoke that's probably 600 to 700 feet...across...at the base...that reaches 3 or 10 miles up. Nice, thick, black, toxic, asthma/cancer causing smoke.

Of course, if we went nuclear, we'd have to deal with the possibility that someone got past all the background checks to get into the facility, got through the security to get somewhere where they could do something, and once they got there, had the time alone to go about doing something that would breach all of the safety and redundandt safety systems we have. Or they could attack with guns or an airplane. Supposing they made it through the no-fly zone in 1 or 2 large pieces, they'd then have to make it through several layers of several foot thick reinforced concrete. Not to mention they'd have to be pretty damn accurate. And I feel sorry for anyone who tried to storm it by ground, considering there's an army base an hour or so outside of town. Yeah, where they grabbed a bunch of the guys in Iraq from. The one where they train all the special forces guys. Seriously, taking a nuclear powerplant near Houston would be like playing a 1 on 1000 game of Rogue Spear. Only shorter.

Whereas, taking out one of our dozen or so oil refineries would be about as hard as sitting down and waiting for it to happen on its own. Maybe driving by and throwing a cigarette out the window if you were in a hurry. I hope you enjoy your Ford Excursion now, cause once we've gone up in greasy, black, yet not radioactive (oh thank god...) fireball, its gonna cost a wee little bit more to drive...

Re:Terrorism and nuclear facilities

[jimmyswimmy]

There is definitely no "no-fly" zone around US nuke plants. As the parent points out, this is a good thing - it would be tough as hell to fly out of several airports.

As a private pilot I am aware of the latest rules and, for once, I am prepared to back up these assertions. According to the JCS NOTAM (NOtice To AirMen) office at https://www.notams.jcs.mil/

A0008/03 (FDC 3/1655) - ...SPECIAL NOTICE... FLIGHT RESTRICTIONS. PURSUANT TO 14 CFR SECTION 99.7, SPECIAL SECURITY INSTRUCTIONS, PILOTS CONDUCTING FLIGHT OPERATIONS WITHIN THE TERRITORIAL AIRSPACE OF THE U.S. ARE ADVISED TO AVOID THE AIRSPACE ABOVE OR IN PROXIMITY TO ALL NUCLEAR POWER PLANTS. PILOTS SHOULD NOT CIRCLE OR LOITER IN THE VICINITY OF SUCH FACILITIES. PILOTS WHO DO SO CAN EXPECT TO BE INTERVIEWED BY LAW ENFORCEMENT PERSONNEL AT THEIR DESTINATION AIRPORT AND THE PILOT'S NAME MAY BE ADDED TO THE TRANSPORTATION SECURITY ADMINISTRATION (TSA INCIDENT REPORTING SYSTEM. WIE UNTIL UFN

In other words, if you screw around (maybe using the cooling stacks as your reference for "turns about a point," for example) over a nuclear power plant, you can expect that your life will be made to totally suck. I mean, who cares about having to talk to the cops afterwards (probably at gunpoint) -- the TSA "Incident Reporting System" is not a database that I want my name attached to. I have to fly commercially way too much for THAT flag to be raised on me.