Editing Three Mile Island accident (section)

==Emergency declaration and immediate aftermath==
At 6:56{{nbs}}a.m. a plant supervisor declared a [[Nuclear safety in the United States#Emergency Classifications|site area emergency]], and less than 30 minutes later station manager Gary Miller announced a general emergency.<ref>{{cite book |last=Walker |first=J. Samuel |url=https://archive.org/details/threemileislandn00walk/page/79/mode/1up |title=Three Mile Island: A Nuclear Crisis in Historical Perspective |date=2004 |publisher=University of California Press |isbn=0-520-23940-7 |location=Berkeley, California |pages=79 |quote=At 6:56 A.M., one of the plant supervisors—accounts vary on which one—declared a site emergency. The emergency plan for TMI-2 directed that this action be taken if radiation alarms sounded in more than one area. A site emergency meant that there was a possibility of an "uncontrolled release of radioactivity" within the plant's boundaries. It required evacuation of the affected buildings, closure of the gates leading to the plant, and notification of the NRC and the state of Pennsylvania. Less than half an hour later..., the Three Mile Island station manager, declared a general emergency... New and alarmingly high radiation readings in the containment building persuaded him to announce a general emergency, which was defined as having the "potential for serious radiological consequences to the health and safety of the general public." |access-date=October 24, 2021}}</ref> [[FirstEnergy|Metropolitan Edison]] (Met Ed) notified the [[Pennsylvania Emergency Management Agency]], which in turn contacted state and local agencies, Pennsylvania [[Governor of Pennsylvania|Governor]] [[Richard L. Thornburgh]] and [[Lieutenant Governor of Pennsylvania|Lieutenant Governor]] [[William Scranton III]], to whom Thornburgh assigned responsibility for collecting and reporting on information about the accident.<ref>{{cite book |last=Walker |first=J. Samuel |url=https://archive.org/details/threemileislandn00walk/page/80/mode/1up |title=Three Mile Island: A Nuclear Crisis in Historical Perspective |date=2004 |publisher=University of California Press |isbn=0-520-23940-7 |location=Berkeley, California |pages=80, 81 |quote=Thornburgh assigned responsibility for collecting and reporting information about the accident to Scranton because of his confidence in the ability and integrity of the lieutenant governor. |access-date=October 24, 2021}}</ref> The uncertainty of operators at the plant was reflected in fragmentary, ambiguous, or contradictory statements made by Met Ed to government agencies and to the press, particularly about the possibility and severity of off-site radioactivity releases.<ref>{{cite book |last=Walker |first=J. Samuel |url=https://archive.org/details/threemileislandn00walk/page/80/mode/1up |title=Three Mile Island: A Nuclear Crisis in Historical Perspective |date=2004 |publisher=University of California Press |isbn=0-520-23940-7 |location=Berkeley, California |pages=80–84 |quote= |access-date=October 24, 2021}}</ref>

Scranton held a press conference in which he was reassuring, yet confused, about this possibility, stating that though there had been a "small release of radiation...no increase in normal radiation levels" had been detected. These were contradicted by another official, and by statements from Met Ed, who both claimed that no radioactivity had been released.<ref>{{cite book |last=Walker |first=J. Samuel |url=https://archive.org/details/threemileislandn00walk/page/80/mode/1up |title=Three Mile Island: A Nuclear Crisis in Historical Perspective |date=2004 |publisher=University of California Press |isbn=0-520-23940-7 |location=Berkeley, California |pages=80–84 |language=en-us |quote= |access-date=October 24, 2021}}</ref> Readings from instruments at the plant and off-site detectors had detected radioactivity releases, albeit at levels that were unlikely to threaten public health as long as they were temporary, and providing that containment of the then highly contaminated reactor was maintained.<ref>{{cite book |last=Walker |first=J. Samuel |url=https://archive.org/details/threemileislandn00walk/page/84/mode/1up |title=Three Mile Island: A Nuclear Crisis in Historical Perspective |date=2004 |publisher=University of California Press |isbn=0-520-23940-7 |location=Berkeley, California |pages=84–86 |language=en-us |quote=The levels measured outside TMI-2 on March 28 were, by any standard, very small and unlikely to threaten public health—as long as they did not occur continuously over an extended period. Met Ed had twenty instruments for measuring environmental radioactivity in locations surrounding the site. Although one stack monitor that was calibrated to measure very low levels of radiation went off-scale early in the accident, readings from other instruments provided reasonably reliable information about releases from the plant. The highest reading was 7 millirems per hour; most measurements were in the range of 1 millirem per hour or less. Those values were far below the amount of radiation normally present in the environment. |access-date=October 24, 2021}}</ref>

Angry that Met Ed had not informed them before conducting a steam venting from the plant, and convinced that the company was downplaying the severity of the accident, state officials turned to the NRC.<ref>{{cite book |last=Walker |first=J. Samuel |url=https://archive.org/details/threemileislandn00walk/page/87/mode/1up |title=Three Mile Island: A Nuclear Crisis in Historical Perspective |date=2004 |publisher=University of California Press |isbn=0-520-23940-7 |location=Berkeley, California |pages=87 |language=en-us |quote=...Scranton held his second news conference of the day... "At this point, we believe there is still no danger to public health." Scranton's statements left no doubt that the state had written off the utility as a partner in responding to the accident. The state hoped that it would realize greater benefits in its efforts to guard public health by collaborating with the NRC. As Critchlow recalled, "I think we just almost instinctively preferred to deal with NRC people." |access-date=October 24, 2021}}</ref> After receiving word of the accident from Met Ed, the NRC had activated its emergency response headquarters in [[Bethesda, Maryland]], and sent staff members to Three Mile Island. NRC chairman [[Joseph Hendrie]] and commissioner Victor Gilinsky<ref>{{cite web |title=Victor Gilinsky |url=https://www.nrc.gov/about-nrc/organization/commission/former-commissioners/gilinsky.html |publisher=U.S. Nuclear Regulatory Commission |access-date=March 6, 2018}}</ref> initially viewed the accident as a "cause for concern but not alarm".<ref>{{cite book |last=Walker |first=J. Samuel |url=https://archive.org/details/threemileislandn00walk/page/89/mode/1up |title=Three Mile Island: A Nuclear Crisis in Historical Perspective |date=2004 |publisher=University of California Press |isbn=0-520-23940-7 |location=Berkeley, California |pages=89 |language=en-us |quote=Like [[Joseph Hendrie|Hendrie]], Gilinsky regarded it as cause for concern but not alarm. He tried to keep his previously scheduled appointments to avoid the appearance of a crisis and, in his capacity as acting chairman, he spent much of the day responding to telephone queries from members of Congress and reporters. |access-date=October 24, 2021}}</ref> 

Gilinsky briefed reporters and members of Congress on the situation and informed White House staff, and at 10:00&nbsp;a.m. met with two other commissioners. However, the NRC faced the same problems in obtaining accurate information as the state and was further hampered by being organizationally ill-prepared to deal with emergencies, as it lacked a clear [[command structure]] and did not have the authority either to tell the utility what to do or to order an evacuation of the local area.<ref>{{cite book |last=Walker |first=J. Samuel |url=https://archive.org/details/threemileislandn00walk/page/91/mode/1up |title=Three Mile Island: A Nuclear Crisis in Historical Perspective |date=2004 |publisher=University of California Press |isbn=0-520-23940-7 |location=Berkeley, California |pages=90, 91 |language=en-us |quote=By tradition, structure, and statutory mandate, the agency was ill prepared and ill equipped to deal with an emergency at a nuclear plant. It was not an operational agency that ran plants or carried out emergency procedures but a deliberative agency that made rules, considered license applications, and conducted inspections. It had no authority to tell the utility what it should do to stabilize the reactor, no capability for operating the plant, and no power to order an evacuation of the surrounding area. Its role was largely limited to collecting information and making recommendations. The NRC lacked a command structure for dealing with a major accident. |access-date=October 24, 2021}}</ref>

In a 2009 article, Gilinsky wrote that it took five weeks to learn that "the reactor operators had measured fuel temperatures near the melting point".<ref name=Gilinsky2009>{{cite journal |last=Gilinsky |first=Victor |title=Behind the scenes of Three Mile Island |journal=[[Bulletin of the Atomic Scientists]] |date=March 23, 2009 |url=http://thebulletin.org/web-edition/features/behind-the-scenes-of-three-mile-island |access-date=March 31, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090815015736/http://thebulletin.org/web-edition/features/behind-the-scenes-of-three-mile-island |archive-date=August 15, 2009}}</ref> He further wrote: "We didn't learn for years—until the reactor vessel was physically opened—that by the time the plant operator called the NRC at about 8:00&nbsp;a.m., roughly half of the [[Nuclear fuel|uranium fuel]] had already melted."<ref name="Gilinsky2009"/>

It was still not clear to the control room staff that the primary loop water levels were low and that over half of the core was exposed. A group of workers took manual readings from the [[thermocouple]]s and obtained a sample of primary loop water. Seven hours into the emergency, new water was pumped into the primary loop and the backup relief valve was opened to reduce pressure so that the loop could be filled with water. After 16&nbsp;hours, the primary loop pumps were turned on once again, and the core temperature began to fall. A large part of the core had melted, and the system was dangerously radioactive.{{Citation needed|date=March 2018}}

On the day following the accident, March 29, control room operators needed to ensure the integrity of the reactor vessel. In order to do this, someone needed to draw a [[boron]] concentration sample in order to ensure there was enough of it in the primary system to shut down the reactor entirely. Unit 2's chemistry supervisor, Edward "Ed" Houser, volunteered to draw the sample after his co-workers were hesitant. Shift supervisor Richard Dubiel asked Pete Velez, the [[radiation protection]] foreman for Unit 2, to join Houser. Velez would monitor airborne radiation levels and ensure that no [[Radiation exposure|overexposure]] would occur for either of them.<ref>{{Cite book |last=Gray |first=Mike |url=https://www.worldcat.org/oclc/52158956 |title=The warning : accident at Three Mile Island |date=2003 |publisher=Norton & Co |others=Ira Rosen |isbn=0-393-32469-9 |location=New York |oclc=52158956}}</ref><ref>{{Cite news |last=Richman |first=Alan |date=1979-04-04 |title=Radiation Overdose: All in a Day's Work |url=https://www.nytimes.com/1979/04/04/archives/radiation-overdose-all-in-a-days-work-feels-a-little-tired.html |access-date=2023-01-26 |work=The New York Times |language=en-US |issn=0362-4331}}</ref><ref>{{Cite web |last=Yuhas |first=Gregory |date=July 4, 1979 |title=Transcript of TMI-2 investigation with EW Houser |url=https://www.nrc.gov/docs/ML1924/ML19249B027.pdf |website=[[Nuclear Regulatory Commission]]}}</ref><ref>{{Cite web |last=Donaldson |first=Dale |date=July 6, 1979 |title=Transcript of TMI investigation interview of P Velez, Met Ed |url=https://www.nrc.gov/docs/ML1920/ML19208B107.pdf |website=[[Nuclear Regulatory Commission]]}}</ref>

Wearing excessive amounts of protective clothing—three pairs of gloves, one pair of rubber boots and a [[respirator]]—the two navigated the reactor auxiliary building to draw the sample. However, Houser had lost his [[Film badge dosimeter|pocket dosimeter]] while taking measurements. Houser had noted the sample he drew looked "like [[Alka-Seltzer]]" and was highly radioactive, with readings as high as 1,000&nbsp;rem/h. The two spent five minutes in the building, then withdrew. Houser had gone past the NRC's quarterly dose limit for radiation exposure (3 rem/qtr in 1979) by one and was only admitted back to work the following quarter.<ref>{{Cite book |last=Gray |first=Mike |url=https://www.worldcat.org/oclc/52158956 |title=The warning : accident at Three Mile Island |date=2003 |publisher=Norton & Co |others=Ira Rosen |isbn=0-393-32469-9 |location=New York |oclc=52158956}}</ref><ref>{{Cite news |last=Richman |first=Alan |date=1979-04-04 |title=Radiation Overdose: All in a Day's Work |url=https://www.nytimes.com/1979/04/04/archives/radiation-overdose-all-in-a-days-work-feels-a-little-tired.html |access-date=2023-01-26 |work=The New York Times |language=en-US |issn=0362-4331}}</ref><ref>{{Cite web |last=Yuhas |first=Gregory |date=July 4, 1979 |title=Transcript of TMI-2 investigation with EW Houser |url=https://www.nrc.gov/docs/ML1924/ML19249B027.pdf |website=[[Nuclear Regulatory Commission]]}}</ref><ref>{{Cite web |last=Donaldson |first=Dale |date=July 6, 1979 |title=Transcript of TMI investigation interview of P Velez, Met Ed |url=https://www.nrc.gov/docs/ML1920/ML19208B107.pdf |website=[[Nuclear Regulatory Commission]]}}</ref>

On the third day following the accident, a hydrogen bubble was discovered in the dome{{Clarify|date=April 2022}} of the pressure vessel and became the focus of concern. A hydrogen explosion could breach the pressure vessel and, depending on its magnitude, might compromise the integrity of the containment building leading to a large-scale release of radioactive material. However, it was determined that there was no oxygen present in the pressure vessel, a prerequisite for hydrogen to burn or explode. Immediate steps were taken to reduce the hydrogen bubble, and by the following day it was significantly smaller. Over the next week, steam and hydrogen were removed from the reactor using a [[Catalyst#Heterogeneous catalysts|catalytic]] recombiner and by venting directly into the open air.{{citation needed|date=March 2018}}

===Identification of released radioactive material===
The release occurred when the cladding was damaged while the PORV was still stuck open. [[Nuclear fission product|Fission products]] were released into the reactor coolant. Since the PORV was stuck open and the loss of coolant accident was still in progress, primary coolant with fission products and/or fuel was released and ultimately ended up in the auxiliary building. The auxiliary building was outside the containment boundary.

This was evidenced by the radiation alarms that eventually sounded. However, since very little of the fission products released were solids at room temperature, very little [[radiological contamination]] was reported in the environment. No significant level of radiation was attributed to the TMI-2 accident outside of the TMI-2 facility. According to the Rogovin report, the vast majority of the radioisotopes released were noble gases xenon and krypton resulting in an average dose of {{convert|1.4|mrem|uSv|abbr=on}} to the two million people near the plant.<ref>{{cite book |last=Rogovin |first=Mitchell |title=Three Mile Island: a report to the commissioners and to the public. Volume I |date=January 1980 |publisher=U.S. Nuclear Regulatory Commission |location=Washington, D.C. |url=https://www.osti.gov/servlets/purl/5395798 |access-date=October 26, 2021 |pages=25, 153 |doi=10.2172/5395798 |osti=5395798 |quote=The effects on the population in the vicinity of Three Mile Island from radioactive releases measured during the accident, if any, will certainly be nonmeasurable and nondetectable. During the course of the accident, approximately 2.5 million curies of radioactive noble gases and 15 curies of radioiodines were released. These releases resulted in an average dose of 1.4 mrem to the approximately two million people in the site area. This average dose is less than 1 % of the annual dose from both natural background radiation and medical practice. The 1.4-mrem dose may also be compared to differences in annual doses in background radiation from living in a brick versus a frame house, an additional 14 mrem/yr; or living in the high altitude of Denver rather than in Harrisburg, an additional 80 mrem/yr.}}</ref> In comparison, a patient receives {{convert|3.2|mrem|uSv|abbr=on}} from a chest X-ray—more than twice the average dose of those received near the plant.<ref>{{cite web |url=http://www.physics.isu.edu/radinf/risk.htm |title=Radiation and Risk |website=ISU Health Physics Radinf |access-date=March 6, 2018 |url-status=dead |archive-url=https://web.archive.org/web/20170406055010/http://www.physics.isu.edu/radinf/risk.htm |archive-date=April 6, 2017}}</ref> On average, a U.S. resident receives an annual radiation exposure from natural sources of about {{convert|310|mrem|uSv|abbr=on}}.<ref>{{cite web |title=Backgrounder on Biological Effects of Radiation |url=https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/bio-effects-radiation.html |website=NRC Library |publisher=U.S. Nuclear Regulatory Commission |access-date=October 26, 2021 |date=March 2017 |quote=On average, a U.S. resident receives an annual radiation exposure from natural sources of about 310 millirem (3.1 millisieverts or mSv). Radon and thoron gases account for two-thirds of this exposure. Cosmic, terrestrial, and internal radiation account for the rest. Man-made sources of radiation from medical, commercial and industrial activities contribute roughly 310 mrem more to our annual exposure. Among the largest of these sources is a computed tomography scan, which accounts for about 150 mrem. Other medical procedures make up another 150 mrem or so each year. Some consumer products such as tobacco, fertilizer, welding rods, exit signs, luminous watch dials and smoke detectors contribute about 10 mrem per year. The pie chart (on the page) shows the sources that make up the average annual U.S. radiation dose of 620 mrem.}}</ref>

Within hours of the accident, the [[United States Environmental Protection Agency]] (EPA) began daily sampling of the environment at the three stations closest to the plant. Continuous monitoring at 11&nbsp;stations was established on April 1 and was expanded to 31 stations on April 3. An inter-agency analysis concluded that the accident did not raise radioactivity far enough above background levels to cause even one additional cancer death among the people in the area, but measures of [[Beta particle|beta radiation]] were not included because the EPA found no contamination in water, soil, sediment, or plant samples.<ref name="EPA's Role at Three Mile Island">{{cite web |url=http://www.epa.gov/history/topics/tmi/02.htm |title=EPA's Role At Three Mile Island |last=Perham |first=Christine |date=October 1980 |website=EPA.gov |access-date=March 17, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110318094452/http://www.epa.gov/history/topics/tmi/02.htm |archive-date=March 18, 2011}}</ref>

Researchers at nearby [[Dickinson College]]—which had [[radiation monitoring equipment]] sensitive enough to detect Chinese atmospheric atomic weapons-testing—collected soil samples from the area for the ensuing two weeks and detected no elevated levels of radioactivity, except after rainfalls (likely from natural [[radon]] plate-out, not the accident).<ref>{{cite web |url=http://www.threemileisland.org/science/pdfs/what_dickinson_found.pdf |title=What did Dickinson Research Find? |website=ThreeMileIsland.org |access-date=March 17, 2011 |url-status=usurped |archive-url=https://web.archive.org/web/20061003164838/http://www.threemileisland.org/science/pdfs/what_dickinson_found.pdf |archive-date=October 3, 2006}}</ref> Also, the tongues of white-tailed deer harvested over {{convert|50|mi|km|abbr=on}} from the reactor subsequent to the accident were found to have significantly higher levels of cesium-137 than in deer in the counties immediately surrounding the power plant. Even then, the elevated levels were still below those seen in deer in other parts of the country during the height of atmospheric nuclear weapons testing.<ref>{{cite journal |last=Field |first=R. W. |date=June 1993 |title=137Cs levels in deer following the Three Mile Island accident |journal=Health Phys |volume=64 |issue=6 |pages=671–674 |doi=10.1097/00004032-199306000-00015 |pmid=8491625}}</ref> Had there been elevated releases of radioactivity, increased levels of iodine-131 and cesium-137 would have been expected to be detected in cattle and goat's milk samples. Elevated levels were not found.<ref>{{cite web |last1=Battist |first1=Lewis |last2=Buchanan |first2=John |last3=Congel |first3=Frank |last4=Nelson |first4=Christopher |last5=Nelson |first5=Mark |last6=Peterson |first6=Harold |last7=Rosenstein |first7=Marvin |url=http://www.threemileisland.org/downloads/210.pdf |title=Population Dose and Health Impact of the Accident at the Three Mile Island Nuclear Station |date=May 10, 1979 |website=ThreeMileIsland.org |access-date=March 6, 2018 |url-status=usurped |archive-url=https://web.archive.org/web/20120401001347/http://www.threemileisland.org/downloads/210.pdf |archive-date=April 1, 2012}}</ref> A later study noted that the official emission figures were consistent with available [[dosimeter]] data,<ref name=hatch97>{{cite journal |last=Hatch |first=M. |display-authors=etal |title=Comments on "A Re-Evaluation of Cancer Incidence Near the Three Mile Island Nuclear Plant" |url=http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=1469856&pageindex=1 |journal=Environmental Health Perspectives |volume=105 |issue=1 |page=12 |year=1997 |pmid=9074862 |pmc=1469856 |doi=10.1289/ehp.9710512|bibcode=1997EnvHP.105...12H }}</ref> though others have noted the incompleteness of this data, particularly for releases early on.<ref>{{cite journal |last1=Wing |first1=S. |last2=Richardson |first2=D. |last3=Armstrong |first3=D. |title=Reply to comments on 'A reevaluation of cancer incidence near the Three Mile Island' |pmc=1469992 |pmid=9171981 |volume=105 |issue=3 |date=March 1997 |journal=Environ. Health Perspect. |pages=266–268 |doi=10.2307/3433255 |jstor=3433255}}</ref>