Three Mile Island - What Really Happened

a series of unplanned events allowed radiated steam to escape from the reactor federal officials insist the danger is not imminent our concern though about the status of the fuel in the core there's extensive fuel damage on the morning of march 28 1979 exactly 36 seconds after 4 am a series of feed water pumps at unit 2 of the 3 mile island nuclear generating station near harrisburg pennsylvania tripped and the flow of water to the steam generators suddenly stopped two seconds later automated systems did as they were programmed to and shut down the steam turbine and associated electric generator the accident at three mile island was now two seconds old hundred sixty four seconds later two-thirds of unit two's uranium core was without cooling water and was getting half as hot as the surface of the sun so began the worst accident in the history of the u.s nuclear industry a 5 out of 7 on the international nuclear event scale though the accident at 3 mile island left an indelible infamous mark on the public's perception of nuclear power an overwhelmingly negative one that is still traded in on to this day this motivated perception obscures the more complicated truth and the truth is that one of the most covered stories of the 1970s was so poorly communicated to the public that today history remembers three mile island as an unmitigated disaster and not what it actually was an inevitable series of human errors that resulted in a harmless failure this is the true story of the three mile island accident for all the technicality that goes into splitting the atom a nuclear power plant is surprisingly simple rods of fuel are brought close enough together to cause sustained chain reactions which generate a lot of heat that heat is exchanged with water running in a separated loop and turns into steam that steam is used to spin turbines and that makes electricity the steam is then cooled by towers and condensed to re-enter the system and all along the way various systems valves and pressurizers keep the system running smoothly the most important part of a nuclear power plant is the core where fuel typically uranium is kept at the desired water heating temperature by control rods which can be inserted into the core at will to almost instantly soak up the neutrons continuing chain reactions and shut the core down it's a design that despite what politicians may say is impossible to turn into an atomic weapon that being said a reactor core without an ability to cool itself can be extremely dangerous if cooling water were at any time to boil away even a recently shut down core will start heating back up at 2200 degrees fahrenheit superheated water reacts with material in the fuel rods to produce hydrogen and explosive gas and at 5200 degrees fahrenheit the fuel itself melts releasing radioactive materials into the system's water and or eating through the reactor shielding to produce a flow of unstoppable corium arguably the most dangerous substance on earth to protect against all of this the fuel rods that hold the fuel pellets are designed to withstand extreme temperatures and the reactor vessel is a monolith of steel and concrete three mile island's unit 2 reactor was 40 feet of 8 inch thick steel inside of two concrete and steel shields with a total thickness of 9 feet all inside a containment building 193 feet high with reinforced concrete walls four feet thick nuclear power buildings are extremely robust even under enemy fire it's this design that made what happened at three mile island an accident and not a disaster the 1979 accident at three mile island unit two severely damaged the reactor core the following is a to the second sequence of events that killed both tmi's second reactor and the momentum behind nuclear power in the united states 30 seconds after 4 am 10 miles southeast of harrisburg pennsylvania the feed water pump system to the reactor core tripped stopping the flow of water to the steam generators two seconds later the interrupted flow of feed water caused the reactor coolant temperature to increase and the water to expand the pilot operated relief valve opened to release the pressure increase eight seconds later the pressure was still building and the reactor dropped all control rods automatically into the core one second after that nuclear fission in the core had stopped at this point the relief valve should have closed itself to return pressure to the system but it was stuck open a condition for which there was no indication among the control room's hundreds of lights and switches less than a minute into the emergency operators in the control room noticed that the emergency feed water pumps had turned on what the operators did not notice were the two lights that indicated no water was running through those pumps one was covered by an old yellowing maintenance tag no one knows why the second light was missed over the next two minutes the secondary loop of the reactor would boil dry and the emergency core cooling system would kick in attempting to flood the overheating core with one thousand gallons of water per minute however assuming that the in fact blocked emergency pumps were already flowing and not wanting to fill the entire system with water the operators in the control room turned off the emergency cooling system for the next two hours and 20 minutes the relief valve would remain open it had an indicator light only showing that a signal was sent to close it not whether or not it was physically closed allowing over a third of all the coolant water to escape the system after which the core started to overheat had this single valve closed had anyone left the emergency cooling systems on quote the accident at three mile island would have remained little more than a minor inconvenience how does something fail that's difficult to determine for something as complicated as a nuclear reactor the pathway to any accident could have hundreds or thousands of crossroads a meltdown or not could depend on a button not pressed a valve not closed assessing risk and complex systems therefore is incredibly complicated but is discovering every possible pathway to failure even possible as diagrams like these of three mile island's potential turning points try to do was three mile island in fact a normal accident after reactor 2 failed in 1979 it inspired sociologist charles parrow to develop his normal accident theory which postulates that accidents like nuclear meltdowns are inevitable the result of unanticipated interactions of multiple failures within a complex system given the innumerable variations that might cause a failure in a highly complicated system a single stuck valve a pump out of maintenance a plant manager not having his coffee that morning pero argued that three mile island was normal in that it was unexpected incomprehensible uncontrollable and unavoidable normal accidents then were caused by the flap of a butterfly's wing so to speak by systems so complicated that even trivial or random events could lead to chaos the idea of a normal accident revolutionized the academic study of safety and risk an accident failure or disaster in a complex system is never the result of just one thing and by examining them as interweaving webs of causation rather than isolated events we might learn how to prevent them but in the case of the reactor about to partially melt down 10 miles southeast of harrisburg pennsylvania we should have seen it coming according to the report of the president's commission on the accident at three mile island the pilot-operated relief valve the single opening that ultimately led to a reactor meltdown had failed 11 times before march 28 1979 the company that made these reactors babcock and wilcox never told its customers 18 months before the accident in pennsylvania a babcock and wilcox reactor in ohio failed in exactly the same way as three mile island was about to do except operators there caught their mistake quickly a senior engineer at babcock and wilcox wrote an internal memorandum that if the reactor there had been operating at full power it was only operating at seven percent quote it is quite possible perhaps probable that core uncovery and possible fuel damage would have occurred end quote but again babcock and wilcox issued no new instructions to customers this memorandum which quote fell between the cracks was written just 13 months before three mile island had a meltdown then there was tmi's control room which investigators found had key indicator lights on the backs of panels switches out of calibration and tags covering warning panels and never fewer than 52 alarms blinking at all times over 100 alarms would sound when the reactor started to fail in pennsylvania and it was impossible to sort the critical ones from the usual finally the valves that would fail at three mile were in disrepair reportedly boron stalactites more than a foot long hung from these valves and stalagmites were building up from the floor what happened at three mile island may have been a kind of normal accident as charles perro would later define it but it was not unexpected two hours after the accident at three mile island had started low-level radiation alarms were blinking in the unoccupied containment building where the reactor was dying a few minutes later investigations show the fuel in the core was no longer covered by cooling water and would remain uncovered for a maximum of 38 minutes at 6 22 am operators in the unit 2 control room asked if anyone had closed the block valve a backup valve to be shut if the pilot operated relief valve failed the response was i don't know the block valve was then shut the loss of coolant was stopped but the accident continued for some unexplained reason according to the president's commission report the emergency core cooling pumps weren't turned on for another hour at 6 54 the reactor coolant pump was turned on then shut off again 19 minutes later due to heavy vibrations calculations would eventually show that with 8 feet of the 12 foot tall core uncovered temperatures inside would reach at least 4 000 degrees fahrenheit causing major damage to the fuel rods fuel and the reactor structure as it partially melted down several areas of the plant now reported high levels of radiation at seven am three mile island declared a site emergency as the core now threatened quote an uncontrolled release of radioactivity to the immediate environment shortly after three mile island officially declared an emergency rising radiation readings caused emergency workers to evacuate the on-site auxiliary building minutes later a radiation detector at the top of the containment building read eight rims per hour but because the detector was shielded by lead that figure was actually a hundred times higher and closer to 800 rems per hour a dose that would exceed the maximum yearly dose limit for civilians in less than half a second at the same time plant operators finally turned on the emergency core cooling system flooding the reactor with 1 000 gallons of water per minute but they mistakenly shut it off 18 minutes later at 7 24 am three mile island declared a general emergency a quote incident that has the potential for serious radiological consequences to the health and safety of the general public during his deposition engineer william dornseif would remember what he said at that moment quote i said to myself this is the biggie the traffic reporter at harrisburg's wkbo radio station was using a cb radio to scan for police chatter at 8 am he heard something good police and firefighters were mobilizing near middletown the closest area to the nuclear power plant wkbo's news director called the plan shortly thereafter but he accidentally got his call routed directly to the control room and to one of the operators scrambling to bring the core back under control quote i can't talk right now we've got a problem a man said the man then denied there being any fire engines headed towards the plant and told the news director to call the local utility company at 8 25 am the public found out what was happening at three mile island not from the plant itself not from public relations not from any regulatory body but from a top 40 music station this is mike pinczak in the kbo newsroom met ed company officials had to shut down their three-mile island nuclear power station unit number two this morning after an accident occurred within the plant's turbine system so began a media frenzy that made the three-mile island accident one of the most reported stories of the decade and what has to be one of the worst pr disasters of all time in retrospect it's not surprising that the memory of three mile island is so negative and so inaccurate while reactor operators were still trying to soothe the dying core core manufacturer babcock and wilcox made the conscious decision not to comment on the incident even when company officials believed misinformation was being made available to the public according to the president's commission during press conferences official sources of information appeared unprepared confused and many times contradictory the nuclear regulatory commission now in contact with three mile didn't provide enough technical experts for interview and so local and national reporters had extreme difficulty in interpreting the specifics of the event the probability of a true disaster and the releases of radiation and their possible health effects in turn a distorted and confusing picture was presented to the public similarly politicians learned about the accident from these confusing reports and not from their own emergency preparedness people at one point lieutenant governor william scranton was publicly contradicted about released radiation by information reporters had gathered from the power utility met ed quote this was the first contradictory bit of information that we received and it caused some disturbance scranton later reported the following days were a flurry of that same disturbance on march 29th more than a day after the first pump tripped the power plant began discharging slightly radioactive cooling water that had been accumulating in their tanks now close to overflowing but without notifying any downstream communities or the press the water was harmless the lack of transparency was not friday morning would prove the most consequential for three mile island's legacy during normal operations a reactor like three mile islands generates radioactive gas more specifically the noble gases krypton and xenon this gas builds up in the reactor over time and is stored in a tank where the short-lived krypton and xenon isotopes can safely decay away at 7 10 am on friday morning a supervisor monitoring the rising pressures from these gases made the decision to open the valves and transfer them to the decay tank he knew that because of leaks in the system this would release radioactive gas into the environment he ordered the transfer anyway without telling either the power utility or other three mile island officials and one minute after 8 a.m a helicopter reported a reading of 1200 milligrams per hour above the plant's vent stack it was over an hour before the supervisor told anyone what he did the lack of communication between operators utilities regulators and public officials can only be described as a meltdown of another sort just before noon the vice president of power generation at met ed was pressed for more information at a briefing reporters already knew that 1200 milligrams per hour was somewhere at the plant the met at official pictured here did not they asked him for clarification whether the radiation was controlled whether it was from the discharge water whether it was on-site or off i hadn't heard the number 1200 he answered i don't know why we need to tell you each and everything that we do specifically end quote that sentence marked the end of met ed's credibility with the media at almost the exact same time met ed was melting down publicly pennsylvania governor richard thornberg got a call it was the president of the united states 40 minutes later the governor had a meeting with his aides an advisory went out from the governor's office shortly thereafter something that was arguably the most impactful thing that happened during the accident all pregnant women and preschool children were encouraged to leave the area within a five mile radius of the power plant until further notice on the morning of the 30th a local man recalled all hell broke loose and we left for delaware to stay with relatives end quote residents fled schools closed health professionals evacuated president jimmy carter would arrive to see three mile island in two days officials on the ground needed to get the situation under control now and then it got worse the friday saturday and sunday after the accident were the most hectic the pennsylvania emergency management agency directed officials to start drawing up wider evacuation plans first 10 miles then 20. six counties 650 000 people 13 hospitals and a prison were inside this radius at 2 pm on march 30th harold denton an expert sent by jimmy carter arrived at three mile island he soon learned that a bubble of approximately one thousand cubic feet of gases had built up inside the reactor core superheated steam was reacting with the zirconium cladding of the uranium fuel rods and producing hydrogen a potentially explosive gas that night denton briefed governor thornberg in person for the first time and then the two men held a press conference no general evacuation orders at this time with the continued exception of pregnant women and young children within 5 miles on saturday investigation of the bubble began unable to see inside the reactor vessel or even enter its building scientists from all over the country from all sides of the problem started calculating hydrogen is explosive but only in the presence of oxygen and some energetic ignition source so the real question was whether or not there was also enough oxygen in the core to spontaneously combust with the hydrogen a potential catastrophe if it ruptured the vessel and exposed fuel to the open air thankfully the three-mile island reactor was rated to withstand the pressure of such a blast but public relations was not throughout the day calculations flew back and forth between scientists there was enough oxygen then there wasn't there were five days before there was enough gas in the core and then there were less than two no definitive answer no sigh of relief or brace for impact the first notice to the public that some nrc officials feared the bubble might explode spontaneously went out at 8 23 pm that day but later that night harold denton would tell the press that quote there is not a combustible mixture in the containment or in the reactor vessel and there is no near-term danger at all end quote this was contradicting yet again reports in the media no there is no disagreement he explained i guess it is just the way things get presented but denton in fact knew there was disagreement and the president of the united states would be there in less than 24 hours to hear about it if it wasn't resolved the night the public learned about the bubble and the uncertainty it pulsed with all hell once again broke loose and emergency preparedness offices throughout central pennsylvania were deluged with worried callers scientists continued calculating and continued disagreeing but now they had a way out they had a much safer potential solution pressurized water reactors like those at three mile normally operated with free hydrogen molecules in the system that way if oxygen did start to build up to dangerous levels it would react with the free hydrogen to form harmless water thereby eliminating the risk of an explosion the infamous hydrogen bubble in unit 2 could be doing the same thing could be eating up any oxygen so as to make explosion impossible scientists just had to prove that the officials that went to the private airport hangar to meet president carter were still debating the oxygen problem seconds before he touched down at 1 pm the president would don some protective wear and tour the three-mile island plant himself thankfully by 4 pm and with help from scientists all around the country on-site engineers had proved it the processes inside the reactor were still violent but they were not explosively so there would never be enough oxygen a few hours later readings would show that the bubble was getting smaller not bigger the accident was getting better not worse but the communication meltdown continued now reading from the report of the president's commission on the accident at three mile island quote by late sunday afternoon nrc which was responsible for the concern that the bubble might explode knew there was no danger of a blast and that the bubble appeared to be diminishing it was good news but good news unshared with the public throughout sunday the nrc made no announcement that it had aired in its calculations or that no threat of an explosion existed governor thornburg was not told of the nrc miscalculation either nor did the nrc reveal the bubble was disappearing that day partially because nrc experts themselves were not absolutely certain end quote it's ironic to commit so hard to making a fool of yourself on april 1st which of these assortments of dots is random human brains tend to think that the dots on the right have no pattern are fair random but they are not it takes some cause some rules some guidance to make each dot for example a comfortable distance away from its neighbor to fill up most of the given space randomness isn't like this randomness is messy clustered it can look like a pattern until you zoom out far enough to see that it is never repeated to discern a true signal from random noise you need to abandon human bias for statistics statistics is especially important in a science like epidemiology where diseases like cancer can be randomly distributed in a population but anecdotally appear like clusters clusters that almost dare you to say correlation equals causation almost all of the radioactivity released from the three-mile island accident was from the planned controlled venting of the krypton and xenon gases on march 30th the total was later established at at least two and a half million curies a direct measure of radioactive decay this amount was less than one percent of the radiation released by the chernobyl disaster and unlike other nuclear nightmares with fission products that linger in the environment for centuries and have an affinity for human bones krypton and xenon is not absorbed by body tissue and is quickly eliminated if inhaled or ingested krypton 85 has a half-life of 10 and a half years xenon 5.3 days if anyone downwind of 3 mile island was to be exposed at ground level as would be later calculated the dose rate they'd receive would be well within the dose someone gets from natural sources over the course of a year in the 43 years since the meltdown at three mile island this fact has been lost and improper correlation has become conspiracy according to every serious publication on the matter including the president's commission a research effort that could fill 300 feet of shelf space in a library with materials the amount of radiation released by the three-mile island accident primarily by short-lived isotopes of krypton and xenon delivered an average possible dose of eight millirem to residents within 10 miles of the plant eight millirem is equivalent to the dose that you get from the minerals in the concrete of your home each year a single chest x-ray and about a third of what every human receives naturally from cosmic radiation annually anecdotal reports have claimed everything from hair loss to poison drinking water to most notably cancer and the people who make a living promoting these claims are still doing so today however read the thousands of pages of journals reports and studies on the subject and the consensus clearly emerges from the randomness there isn't a single peer-reviewed non-anecdotal report of one significant public health effect after the three-mile island accident simply put our collective memory that three-mile island was some kind of horror show of health effects was a false one it's impossible according to the physics cancer is cancer whether unstoppable cell division is caused by random mutation a carcinogen in cigarette smoke or damage from a source of radiation the disease looks the same it's impossible to tell therefore without the epidemiology to tease out whether or not there's an underlying cause whether or not a randomly occurring cancer is being confused with one that is truly caused by something out of the 2 million people living within 50 miles of 3 mile island we know that some 320 000 are likely to die of cancer for reasons that have nothing to do with the power plant being there nearly a majority of people would develop cancer sometime in their lifetime the average projected number of additional cancers added to this 325 000 from the specific amount of radiation released by three mile island is 0.7 not 0.7 percent 0.7 cases and this is an average meaning that there is more than a 50 percent chance less than one person would develop a radiation-induced cancer or in less mathematical terms no one and if someone was unlucky enough to be on the wrong side of this average one case wouldn't be enough to statistically untangle it from the hundreds of thousands of cases undetectable unmeasurable insignificant not insignificant because it wouldn't matter to that person or persons but insignificant because the three-mile island accident was minor enough to be indistinguishable from nothing three-mile island did have one very real and measurable effect on public health however stress think of the anxiety of being told you might hear an explosion at the nuclear power plant next to your home at any moment of both being pregnant and having to leave your home for some unknown amount of time of pulling your kids out of school and trying to explain to them why they have to stay in a shelter and not their own bed while stress was the sole public health effect from three mile island it affected people more than any low-level radiation ever could have it's almost funny the conspiracy theories and anecdotal evidence and anti-nuclear panic that three mile island generated and still generates have likely done more to harm public health through stress than any radiation released in 1979 right for the wrong reasons [Music] the accident at three mile island did not end with a completely calm core and a pacified public evacuation recommendations weren't lifted for a week after the bubble was discovered more than a million gallons of radioactive water were still stored in tanks on site and the plant still planned on venting small amounts of krypton and xenon into the atmosphere over the next two months thanks to the stuck open relief valve workers still had a monumental amount of wiping vacuuming and mopping to do inside the reactor buildings the reactor core itself had been severely damaged it was now structurally unsound and half the fuel inside had melted by 1990 11 years later close to 300 000 pounds of nuclear fuel wreckage and cleaning supplies had been systematically removed and shipped off site 2.23 million gallons of contaminated water had been processed cleanup officially ended in 1993 and cost 1 billion dollars reactor 2 was completely shut down after the accident reactor 1 continued operation for another 30 years until it too ceased operations on september 20th 2019 citing financial pressures from pennsylvania's second in the nation natural gas production in the months following the accident hundreds of thousands of people across the country would stage anti-nuclear protests famous actors and politicians would attend them world famous musicians would hold nightly no nuke concerts at some of the world's biggest venues in 1981 and 1983 utility met ed would lose tens of millions of dollars in lawsuits claiming lost revenue damages and falsified safety records a class-action lawsuit claiming substantial health effects however was rejected in both harrisburg and the u.s third circuit court of appeals after three mile island the number of reactors under construction in the u.s started to decline for the first time since 1963. 51 nuclear reactors were canceled between 1980 and 1984. no new nuclear power plant would be authorized for construction in the united states until 2012. what took their place of course were coal-fired power plants which would soon contribute to more preventable deaths by pollution than all nuclear accidents ever combined the factors that led to three mile island were pervasive and serious lack of transparency in action poorly trained operators unmaintained equipment known hardware errors a lazy safety culture abysmal information sharing with the media and the public for what it's worth three mile island was a wake-up call that did indeed lead to sweeping industry changes but irreversible damage was done in public consciousness nuclear power was now dangerous not the future who knows how different the industry would be today if a single valve 10 miles southeast of harrisburg didn't fail or if president jimmy carter who specialized in nuclear power in the navy had told the nation what he told his staff after visiting the plant that day that he didn't think it was even a disaster he thought it was minor he reportedly refused to tell the public this at the time for fear of offending anti-nuclear democrats in the u.s house and senate despite the lack of any real harm to personnel or public the three-mile island accident was a sizable nail in the nuclear industry's coffin or rather in the coffin of the public's perception of the industry but it wouldn't be the largest that nail would come seven years later after another series of missteps and another arguably unavoidable normal accident the dominoes that would fall one night in 1986 would also be ones of human error poor design and unsafe attitudes and in the dead of night on april 26th the last one fell in chernobyl until next time [Music] [Music] [Music] [Music] foreign

Channel: Kyle Hill

Views: 2,652,444

Keywords: because science, engineering, kyle hill, learning, math, physics, science, stem, the facility, chernobyl, three mile island, nuclear meltdown, nuclear power, 3 mile island, nuclear reactor, nuclear power plant, TMI, three mile island accident explained, three mile island accident documentary, three mile island accident, documentary

Id: cL9PsCLJpAA

Length: 36min 31sec (2191 seconds)

Published: Sun Jun 26 2022

Reddit Comments

[u/b2walton]

The movie China Syndrome was released 12 days before the incident. It's like being a shark the weekend after Jaws.

[u/Gorf_the_Magnificent]

At that time, I thought that the President of Metropolitan Edison Corporation, operators of Three Mile Island, should have driven an RV onto the grounds of the plant and lived there until the accident was contained, to demonstrate that the air around the plant wasn’t significantly contaminated, and nearby residents weren’t affected.

[u/realkylehill]

Thanks for the love here! Really helping the views

[u/Smoovie32]

Half the reactor melted down. Pretty much worse than bad communication no matter which way you look at it.