Meltdown at Three Mile Island

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A stuck valve. A wall of alarms. A company line that insisted everything was “fine.” We walk through the morning when Three Mile Island went from a routine shutdown to America’s most defining nuclear scare—and why the fallout was as much about trust as technology.

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Special thank you to Lunarfall Audio for producing and doing all the heavy lifting on audio editing since April 13, 2025, the Murder of Christopher Meyer episode https://lunarfallaudio.com/

Episode Transcript

SPEAKER_00 (00:01):
On March 28, 1979, a meltdown in the number two
reactor at the Three Mile IslandNuclear Generating Station led
to the worst nuclear accident tooccur in America.
While no injuries or deathswould occur from the accident,
cover-ups would ensue, and thenation's trust in nuclear power

(00:22):
would rapidly diminish.
So, what happened?
I'm Andrew, and this isHistory's A Disaster.
Tonight we are diving into theradioactive waters around Three
Mile Island, near Harrisburg,Pennsylvania, and taking a look

(00:44):
into the accident and cover-upsurrounding the nuclear power
station.
And tonight's episode is broughtto you by Sensitive Steve's
Steam Bats.
Now open 24 hours inPennsylvania, Puerto Rico, and
Guam.
Three Mile Island NuclearGenerating Station was a

(01:07):
pressurized water reactoroperated by Metropolitan Edison
Company, located on theSusquehanna River in London
Berry Township.
Construction on the reactor wasstarted in 1968.
By 1974, reactor 1 was broughtonline.
Reactor 2 would come online in1978.

(01:28):
The community welcomed the powerplant.
Nuclear power was new and cheap,and it meant more good-paying
jobs in an area that desperatelyneeded it.
It was promoted as safe and noone thought of things like
radioactivity or any possibledownsides.
Now, before we get into theaccident, we're going to do a
real quick idiot's guide to howa nuclear reactor works.

(01:51):
The whole process starts in thenuclear reactor core with fuel
rods containing uranium oxidepellets.
These fuel rods are submerged inwater and hit with neutrons.
When the neutrons hit theuranium atoms, fission occurs
and the atom is split, whichcreates a lot of heat and more
neutrons which go on to strikemore atoms, kicking off a chain

(02:15):
reaction and generating a shitton of heat.
The heat is then absorbed by thewater and in a pressurized water
reactor like Three Mile Island,the water is kept under pressure
and pumped out of the corethrough a heat exchanger which
superheats a separate watersystem.
This separate system generatespressurized steam which spins a

(02:36):
turbine.
The rapidly spinning blades ofthe turbine are connected to a
generator which takes themechanical energy from the
turbine and converts it toelectricity.
After going through the turbine,the steam goes through a
condenser where it meets up withcold water, which condenses and
cools the steam, turning it backto water and is pumped back to

(02:57):
the steam generator to start theprocess all over again.
In a pressurized water reactor,the irradiated water is kept in
a closed loop so it never leavesthe reactor.
Now with that out of the way,shortly after 4 a.m.
on March 28, 1979, a water pumpfailed, causing the turbine and

(03:18):
reactor to shut downautomatically as it was designed
to do.
Under normal circumstances, thiswould have been a routine
shutdown requiring minimalintervention.
However, the situation rapidlywent to shit due to a ton of
equipment failures and humanerrors.
The emergency feedwater pumps,which should have been activated

(03:40):
to maintain cooling, wereisolated due to maintenance work
performed two days earlier.
Control room operators, unawareof this critical oversight,
watched helplessly as pressurebegan building in the primary
cooling system.
As pressure mounted, a reliefvalve opened to vent steam, but
then failed to close properly, amalfunction that no one would

(04:04):
notice for hours.
This stuck valve allowedthousands of gallons of
radioactive water to drain fromthe reactor core, creating a
dangerous situation that theplant's designers had never
fully anticipated.
The control room erupted inconfusion and chaos as alarms
sounded and indicator lightsflashed.

(04:25):
Operators trained for routinesituations, but unprepared for
an emergency of this size made aseries of critical errors.
Most significantly, theymisinterpreted the readings and
believed the reactor had toomuch water when, in reality, it
was extremely low.
The two indicator lights thatshowed there was no water

(04:46):
running through the system hadbeen missed.
One was covered over with an oldmaintenance tag, and the second
one, well, no one knows, or atleast no one claims to know, why
it was missed.
Acting on this false assumption,they reduced the flow of

(05:06):
emergency cooling water,inadvertently accelerating the
crisis.
By 6 a.m., one-third of thereactor core had been uncovered
by coolant.
Without adequate cooling, thenuclear fuel began to overheat
dramatically.
Temperatures inside the coresoared to over 4,000 degrees
Fahrenheit, hot enough to startmelting the fuel rods of uranium

(05:30):
fuel pellets.
This partial meltdown releasedradioactive gases and created a
potentially explosive hydrogenbubble within the reactor
vessel.
The plant's operators, stillstruggling to understand the
true nature of the emergency,continued to make decisions
based on incomplete andmisleading information.

(05:51):
The control room'sinstrumentation, designed for
normal operations, providedconfusing and contradictory
readings during the emergency.
Critical indicators showed thereactor vessel was full of water
when it was actually now halfempty, leading operators to
believe their actions wereappropriate when they were
actually fucking it up evenmore.

(06:13):
As the morning went on,radiation levels within the
containment buildingskyrocketed.
Radioactive gases began ventingfrom the plant, though,
initially in small quantities,the reactor core continued to
deteriorate, with fuel pelletsmelting and forming a molten
mass at the bottom of thereactor vessel.

(06:34):
For several hours, plantofficials feared that this
molten fuel might burn throughthe reactor vessel and
containment structure.
Meded's initial response wasconfused, poorly communicated,
and they seriously downplayedjust how bad things actually
were.
Company officials, either poorlyinformed by plant operators or

(06:57):
reluctant to acknowledge thescope of the problem, issued
reassuring statements to localauthorities and the media that
proved to be wildly inaccurate.
They told the media, it's fine,everything is fine, nothing to
see here.
At 7 a.m., MedEd notified thePennsylvania Emergency
Management Agency that aquote-unquote unusual event had

(07:21):
occurred at 3 Mile Island.
An unusual event is the lowestlevel of nuclear emergency
classification, which was aserious understatement.
Part of the reactor core hadalready melted and radioactive
materials were being released,but it was just an unusual
event.
It hasn't blown up yet, so it'llbe fine.

(07:43):
Local emergency officials,relying on information from
MedEd, initially saw no causefor alarm.
The company's public relationsteam, either uninformed about
the true situation ordeliberately downplaying the
crisis, assured reporters thatthe plant was operating safely
and that there was no threat topublic health.

(08:05):
These early statements wouldlater prove not only false, but
dangerously misleading,contributing to public confusion
and undermining the trust inboth the company and nuclear
authorities.
Meanwhile, inside the plant,workers were beginning to grasp

(08:26):
the true magnitude of thedisaster.
Radiation monitors throughoutthe facility showed readings far
exceeding normal levels.
Plant personnel evacuatednon-essential workers from the
reactor building, and those whoremained worked in rotating
shifts to minimize radiationexposure.
As the hours passed, it becameincreasingly clear that MedEd

(08:49):
officials were either unaware ofthe true severity of the
accident or were deliberatelyattempting to minimize its
significance.
This information management,whether born of ignorance or
intent, constituted a cover-upthat would have serious
consequences for public safetyand trust.
Company executives, briefed byplant officials who themselves

(09:12):
may not have fully understoodthe situation, continued to
issue statements thatcontradicted the growing
evidence of a serious accident.
When pressed by reporters aboutradiation releases, MedEd
spokesmen acknowledged onlyminor, acceptable levels of
radioactivity, failing tomention that significant

(09:34):
quantities of radioactive gaseshad been vented from the plant.
No one's grown a third arm yet,so obviously there is no need to
worry.
Company documents later showedthat MedEd officials were aware
much earlier than they publiclyadmitted to that substantial
fuel damage had occurred.
However, this information wasnot shared with state and

(09:56):
federal authorities, hamperingemergency response efforts and
leaving the locals in the darkabout potential risks to their
health and safety.
The company's reluctance tofully disclose the severity
extended to its interactionswith the Nuclear Regulatory
Commission.
NRC officials depended oninformation provided by MedEd.

(10:18):
They initially accepted thecompany's assessment that the
situation was under control.
It wasn't until NRCinvestigators arrived on site
and conducted their own analysisthat they realized how fucked up
things actually were.
By the afternoon of March 28th,independent radiation monitoring

(10:39):
by state authorities began topaint a different picture than
the one presented by MedEd.
Pennsylvania's Department ofEnvironmental Resources detected
radiation levels significantlyhigher than those reported by
the company, creating the firstmajor discrepancy between
official accounts andindependent measurements.

(11:01):
Dr.
Thomas Garuski, director ofPennsylvania's Bureau of
Radiation Protection, becameincreasingly concerned as his
team's readings contradictedMedEd's assessments.
Garuski's office detectedradiation plumes extending
several miles from the plant,indicating that more substantial

(11:21):
releases had occurred than thecompany had admitted to.
Federal authorities also beganto express concern.
The NRC, initially believingMedEd's bullshit idea that it
was just a minor incident,started sending additional
personnel to the site asconflicting reports emerged.
NRC officials, trained to beskeptical of utility company

(11:44):
assessments during emergencies,began conducting their own
independent evaluation of thesituation.
Media coverage, initiallylimited and largely based on
med-ed press releases, began tointensify as reporters
recognized inconsistencies inthe official account.
Television news crews arrived atthe plant, broadcasting images

(12:08):
of the facility and interviewinglocal residents who were
beginning to express concernsabout their safety.
The visual impact of the coolingtowers, surrounded by steam and
emergency vehicles, painted acompletely different picture
from what MedEd was saying.
Local residents, many of whichlived within sight of the

(12:29):
plant's cooling towers, startedquestioning the official
accounts as emergency vehiclesmultiplied around the facility
and rumors of evacuated plantworkers spread throughout the
town.
Phone calls to state authoritiesincreased dramatically, with
citizens demanding answers aboutradiation levels and potential

(12:50):
health risks.
On March 30th, two days afterthe initial accident, the crisis
took on a new and potentiallycatastrophic dimension with the
discovery of a large hydrogenbubble inside the reactor

(13:10):
vessel.
This changed the situation fromextremely serious into what
could be considered anuncontrolled disaster.
Hydrogen gas had been generatedduring the accident when
superheated steam reacted withthe zirconium cladding of the
fuel rods, a process that occursat extremely high temperatures.
This hydrogen had gathered inthe upper portion of the reactor

(13:33):
vessel, creating a bubble thatposed multiple dangers.
If the hydrogen concentrationreached critical levels and
encountered an ignition source,it could explode with enough
force to breach the reactorvessel and potentially
contaminate the structureitself.
The discovery of the hydrogenbubble marked a turning point in

(13:54):
both the technical management ofthe accident and its public
perception.
NRC officials, now fully engagedin managing the crisis,
struggled to determine whetherthe bubble posed an immediate
explosion risk?
Initial calculations suggestedthat the hydrogen concentration
might be approaching dangerouslevels, leading to urgent

(14:16):
discussions about worst-casescenarios.
Dr.
Harold Denton, the NRC'sDirector of Nuclear Reactor
Regulations, was sent to ThreeMile Island to take direct
control of the federal response.
With Denton there, MedEgg couldno longer try to control the
narrative.
More accurate information aboutthe true nature of the emergency

(14:38):
was being directly released tothe media.
And the hydrogen bubble crisiscontinued to ramp things up.
It needed to be taken care of asquickly as possible.
Engineers worked frantically todevelop methods for safely
removing the hydrogen withouttriggering an explosion.
Various options were considered,including venting the gas to the

(15:00):
atmosphere, which would releaseadditional radiation, or
attempting to consume thehydrogen through controlled
reactions.
Each choice was incrediblydangerous, but they were quickly
running out of time.
The morning of March 30th,Pennsylvania Governor Richard
Thurnberg recommended theevacuation of pregnant women and

(15:22):
preschool children within a5-mile radius of the plant.
This advisory carefully wordedto avoid panic while
acknowledging the danger,affecting roughly 3,400 people
in the area surrounding 3 MileIsland.
The governor's recommendationrepresented the first official
acknowledgement that theaccident posed a genuine threat

(15:44):
to public health.
Schools within the evacuationzone closed, and many families
with young children left thearea voluntarily.
Hotels and motels throughoutcentral Pennsylvania filled up
quickly with evacuees.
The impact of thisrecommendation extended far
beyond the 3,400 people whichwere directly affected, as

(16:05):
locals throughout the areaquestioned their own safety.
Dornberg's decision was mademore difficult by the absence of
clear federal guidelines fornuclear emergencies.
Unlike natural disasters forwhich established evacuation
procedures existed, nuclearaccidents presented unique
challenges that emergencymanagement systems were not

(16:27):
designed to handle.
The governor was in essenceforced to make shit up as he
went along.
Despite Governor Thurnberg'slimited evacuation
recommendation, a much largerexodus began as news of the
hydrogen bubble spread.
Over 144,000 people, nearly 40%of the population within a

(16:47):
15-mile radius of the plant,left the area, creating one of
the largest peacetimeevacuations in American history.
Distrust of official statementsafter days of contradictory
information, fear of invisibleradiation, and graphic media
coverage that emphasizedworst-case scenarios led to the

(17:08):
mass evacuation.
Television reports showedfamilies loading their shit into
cars and fleeing the area.
Images that reinforced the senseof impending disaster and
encouraged others to leave.
Highways leading away from ThreeMile Island became backed up
with people fleeing.
No one knew where to go or whenthey'd be able to come back.

(17:29):
Their fear was pushing them toget out and get out now.
Gas stations reported long linesand fuel shortages as residents
filled their tanks for uncertainjourneys.
Hotels throughout Pennsylvania,New York, and neighboring states
experienced unprecedented demandas Three Mile Island evacuees
sought temporary shelter.

(17:50):
Businesses within the affectedarea closed or operated with
skeleton crews.
While schools throughout theregion shut down as teachers and
students left the area, farmersworried about radiation
contamination of crops andlivestock while also having to
deal with labor shortages causedby worker evacuations.
Local hospitals, alreadystretched in by staff

(18:13):
departures, prepared forpotential wounded while also
trying to figure out how totreat radiation exposure,
something which most hospitalswere unprepared for.
Medical personnel worked toobtain potassium iodide tablets,
which could help protect againstthyroid cancer caused by
radioactive iodine exposure.

(18:34):
Supplies of this were limitedand distribution plans were
quickly thrown together.
As the crisis continued, federalauthorities launched an
investigation into both thecauses of the accident and
MetEd's handling of theemergency.
The NRC, the EPA, and Departmentof Health and Human Services
sent out experts to assess thesituation and prepare for

(18:57):
potential long-term health andenvironmental consequences.
NRC investigators, led by HaroldDenton, began conducting
detailed analysis of theaccident while also working to
stabilize the reactor.
Their preliminary findingspainted a disturbing picture of
multiple system failures,inadequate operator training,

(19:18):
and design deficiencies that hadcontributed to the severity of
the accident.
The investigation revealed thatthe accident was not the result
of a single catastrophicfailure, but rather a shitload
of smaller problems thatoverwhelmed the plant safety
systems and the ability of theoperators to respond

(19:38):
effectively.
Critical safety equipment hadbeen unavailable due to
maintenance.
Instruments provided misleadinginformation during the
emergency, and operators lackedtraining for the type of complex
accident they faced.
Federal health officials beganmonitoring radiation exposure
levels among plant workers andnearby residents.

(19:59):
While initial assessmentssuggested that radiation
releases had been relativelylimited, the long-term health
implications remained uncertain.
The absence of comprehensiveradiation monitoring systems in
the area hampered efforts toaccurately assess exposure
levels and potential healthrisks.

(20:19):
Environmental monitoringexpanded to include air, water,
soil, and food samples fromthroughout the region.
Agricultural products,particularly milk from dairy
cows that might have consumedcontaminated grass, received
special attention.
These monitoring efforts wouldcontinue for years following the
accident, creating a database ofenvironmental impact that would

(20:43):
help with future nuclear safetyregulations.
As investigators gained accessto plant records and began
interviewing personnel, a morecomplete picture of the accident
emerged.
The investigation revealed notjust technical failures but also

(21:06):
problems with emergencyprocedures, communication
protocol, and corporateoversight.
Investigators discovered thatcritical safety information that
had not been communicated up thechain of command within MedEd,
plant operators struggling withan unheard of emergency had not
clearly conveyed the severity ofthe situation to company

(21:27):
executives, who in turn hadprovided an overly optimistic
view to government officials andthe public.
The investigation also showedthat similar incidents at other
nuclear facilities had not beenadequately analyzed or
communicated to the industry.
A nearly identical accident hadoccurred 18 months earlier at

(21:49):
the Davis Best Nuclear PowerStation in Ohio, but that
information had not been sharedto anyone at Three Mile Island.
Shitty training became apparentas investigators interviewed
workers at the reactor.
Operators had been trainedprimarily for basic routine
operations and simpleemergencies, but not for

(22:10):
anything too complex.
It's a nuclear reactor, afterall.
What could possibly go wrong?
Simulator training, which mighthave helped prepare for more
adverse conditions, wasseriously lacking.
The investigation into MetEd'shandling of the accident showed
they were more concerned withpublic relations and not so much
concerned about public safety.

(22:32):
Internal company documentsobtained through federal
subpoenas showed that executiveswere aware of the accident's
severity earlier than theyclaimed to.
Company officials had receiveddetailed briefings about core
damage and radiation releaseshours before acknowledging these
facts to government authorities.
This delay in accurate reportingnot only slowed down emergency

(22:54):
response efforts, but alsoviolated federal regulations.
Criminal investigations wereinitiated to determine whether
company officials had violatedfederal laws by providing false
information to governmentauthorities or failing to report
required safety information.
In 1983, Meded would end upbeing indicted on 11 counts of

(23:18):
falsifying safety test resultsprior to the accident.
They would end up pleadingguilty and having to pay out an
$11 million settlement alongwith a$45,000 fine.
In the wake of the accident,President Jimmy Carter appointed
a special commission led byDartmouth College President Josh

(23:42):
Kemene to conduct acomprehensive investigation of
the Three Mile Island accident.
The Kemene Commission was themost thorough examination of a
nuclear accident in Americanhistory.
The investigation went beyondthe technical aspects of the
accident to examine the broaderinstitutional failures that had
contributed to the crisis.

(24:04):
Over six months, hundreds ofwitnesses were interviewed,
thousands of documents reviewed,and detailed analysis of
everything from reactor designto emergency communications were
conducted.
And their findings were notgood.
The report concluded that theaccident was preventable and

(24:24):
resulted from a combination ofhuman error, equipment failure,
and institutional inadequacies.
More significantly, thecommission found that the
nuclear industry and itsregulators had become complacent
about safety, relying tooheavily on engineered safety
systems while neglecting humanfactors and emergency

(24:45):
preparedness.
The Commission identifiedfundamental problems with the
regulatory approach to nuclearsafety.
The NRC, the report found, hadfocused too narrowly on
technical compliance withregulations while failing to
ensure that utilities wereactually prepared to operate
nuclear facilities safely.
The regulatory system had becomebureaucratic and inflexible,

(25:09):
unable to adapt quickly to newsafety information or changing
circumstances.
The commission called for majorchanges in reactor design,
operator training, emergencypreparedness, and regulatory
oversight.
The report emphasized thatnuclear safety required a
comprehensive approach thataddressed not just technical

(25:30):
systems, but also human factors,organizational culture, and
emergency response capabilities.
These recommendations would leadto a massive overhaul of nuclear
regulation.
The NRC underwent majorreorganization with new emphasis
on safety culture, the emergencypreparedness and human factor in

(25:50):
nuclear plant design andoperations.
New regulations requiredenhanced operator training,
including more extensivesimulator-based education that
exposed personnel to complexaccident scenarios.
Control room design standardswere revised to improve the
presentation of critical safetyinformation and reduce the

(26:12):
potential for operator confusionduring emergencies.
Emergency planning requirementswere substantially strengthened.
Nuclear utility companies wererequired to develop detailed
evacuation plans in coordinationwith local authorities, and
regular emergency exercisesbecame mandatory.
FEMA was given expandedresponsibilities for coordinated

(26:36):
nuclear emergency response.
The regulatory approach tonuclear safety shifted.
Companies were now required todemonstrate not just that their
equipment met technicalspecifications, but that their
organizations were capable ofsafely operating nuclear
facilities under both normal andemergency conditions.

(27:09):
The Unit 2 reactor, damagedbeyond repair, was permanently
shut down.
The nuclear industry as a wholefaced immediate financial
impacts as orders for new plantswere cancelled or delayed.
Public opposition to nuclearpower, already growing before
the accident, intensifieddramatically.

(27:30):
Utility companies reconsideredtheir nuclear expansion plans,
leading to the cancellation ofdozens of planned reactors.
Construction costs for nuclearplants increased significantly
as new safety requirements wereimplemented.
Enhanced training programs,improved control room designs,
and strengthened emergencypreparedness systems all added

(27:54):
to the expense of nuclear powerdevelopment.
These costs, combined withgrowing public acquisition, made
nuclear power less economicallyattractive compared to
alternative energy sources.
The cleanup of Three MileIsland's damaged Unit 2 reactor
became one of the most complexand expensive decontamination
projects in industrial history.

(28:15):
The process, which would takenearly 12 years and cost over$1
billion, presented technicalchallenges and raised difficult
questions about nuclear wastemanagement.
They had to first remove theradioactive water that had
gathered in the reactorbuilding.
There was over 700,000 gallonsof contaminated water that had
to be processed to removeradioactive waste before it

(28:37):
could be safely disposed of.
This process would require thedevelopment of new filtration
and decontaminationtechnologies.
Even worse than this wasremoving the damaged fuel rods.
The partial meltdown had createda mix of melted fuel, structural
materials, and debris that hadnever been encountered before.

(28:58):
They had to make special toolsand techniques to safely remove
this highly radioactive materialwithout exposing workers to
dangerous radiation levels.
The cleanup process provedinvaluable in providing insights
into accident recoveryprocedures that helped emergency

(29:20):
planning at other nuclearfacilities.
Techniques developed for remotehandling of radioactive
materials, decontamination ofcontaminated surfaces, and
protection of cleanup workersbecame standard practice for
nuclear maintenance operations.
Environmental monitoringcontinued throughout the cleanup
process with regular testing ofair, water, and soil samples to

(29:42):
ensure that radioactivematerials were not being
released into the air.
These monitoring programsprovided extensive data on the
environmental fate ofradioactive materials released
during a nuclear accident.
While immediate radiationreleases were determined to be
minor, concerns about potentialcancer.
Cancer risk and other healtheffects persisted among

(30:02):
residents.
Multiple studies were conductedto check the health of people
living near Thirma Island.
These studies were ran by bothfederal, state, and independent
researchers and continued on fordecades afterwards, attempting
to identify any excess cancerrates or other health problems
that might be attributed to theradiation exposure, while

(30:24):
radiation exposure wasrelatively low, making it
difficult to detect healtheffects above background levels.
Initial studies suggested thatradiation exposures were below
levels typically associated withincreased cancer risk, but these
findings were met withskepticism by the locals.
Some of them reported increasedrates of cancer and other health

(30:44):
problems.
Trying to figure out whether ornot it was caused by the
accident or not proved to bepretty challenging.
This uncertainty would become asource of controversy among the
residents.
They felt that the governmentand industry assurances about
safety were not credible giventhe pattern of lies during the
accident.
They refused to be fooled again.

(31:05):
They took a fool me once typeattitude.
Because of all these concernsand the growing opposition to
nuclear power, it would put astop to the rapid nuclear power
expansions.
No new nuclear plants wereordered in the United States for
more than 30 years, and manyexisting orders for plants were
canceled.
The combination of increasedsafety requirements, public

(31:27):
opposition, and economicuncertainty made nuclear power
development politically andfinancially difficult.
This, despite the accidentleading to improvements in
nuclear safety that madeexisting plants safer and more
reliable.
And that was the nuclearaccident at Three Mile Island.

(31:48):
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(32:08):
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