Three Mile Island
Accident of 1979
Knowledge
Management Digest
Overview
NUREG/KM-0001, Revision 1
Office of Nuclear Regulatory ResearchThree Mile Island on April 10, 1979, 13 days after the accident

iiContents
Digital Versatile Disc (DVD) Contents ............................................. v
1

Introduction ............................................................................... 1

2

The Accident ............................................................................. 3

3

Investigations and Lessons Learned ......................................... 9

4

Regulatory Actions .................................................................. 13

5

Research ................................................................................ 17

6

Plant Recovery and Cleanup ................................................... 21

7

Retrospectives ........................................................................ 29

8

DVD Navigation and Interpretation .......................................... 33

9Contributions to the Main Report ............................................. 37

President Jimmy Carter observes the radiation monitors in the Three Mile
Island, Unit 2 control room on April 1, 1979, accompanied by
Pennsylvania Governor Richard Thornburgh and the NRC’s Harold
Denton.

iii

Location of dosimetry sites within a 2 mile radius of the Three Mile Island
station. NRC deployed thermoluminescent dosimeters at 37 offsite locations on
March 31, 1979, and an additional 10 locations the following day. NRC placed
portable air samplers around the plant area and observation center andanalyzed the results. NRC also placed liquid effluent monitors at the station
discharges.

iv

Digital Versatile Disc (DVD) Contents
Main Report Disc (NUREG/KM-0001, DVD-1)

FolderPhotos & Videos
Photo Gallery
DOE “The TMI Story: A Documentary” (1988)
NRC 30th Anniversary Seminar (2009)
NRC 35th Anniversary Seminar (2014)

0a-Photos
0b-Video-DOE
0c-Video-30th
0d-Video-35th

Response to the Accident
Commission/Operations Center Response
Response Preliminary Notices
Press Releases/Conferences
International Cables
Other Response

1a-Transcript
1b-PN-Response
1c-Press
1d-International
1e-OtherInvestigations and Lessons Learned
President's Commission
Rogovin Investigation
NRC Investigations
Other Investigations

2a-Kemeny
2b-Rogovin
2c-L2-NUREG
2d-OtherIndustrywide Regulatory Actions
Generic Communications
Policy Statements
NUREG Reports

3a-Generic3b-Policy
3c-REG-NUREGv

An aerial view of Three Mile Island looking south. TMI-2 and both of its
cooling towers are in the background. Although the island, which is locatedon the Susquehanna River, is almost three miles long, the island was named
from its location three miles downriver from Middletown, PA. (Middletown
was founded in 1755 and named from its location halfway between Lancasterand Carlisle, PA.)vi

1 Introduction
Although it caused no deaths or injuries, the accident at the Three Mile
Island, Unit 2 (TMI-2) nuclear power plant was the most serious incident in
U.S. commercial nuclear power history. The accident began in the earlymorning hours of March 28, 1979, at the newly-licensed power plant near
Middletown, Pennsylvania, and its effects on nuclear safety and regulation
continue to this day. Three Mile Island spurred the U.S. Nuclear Regulatory
Commission (NRC) to tighten and heighten its regulatory oversight of thenuclear power industry to ensure the safety of the public and theenvironment. Investigations and the implementation of lessons learned
brought about sweeping changes in the U.S. nuclear industry. These
included improvements in emergency response planning, reactor operator
training, human factors engineering, radiation protection, and many otherareas of nuclear power plant operations and design. The NRC and the
U.S. Department of Energy (DOE) have intensively studied anddocumented the TMI-2 accident.
This multimedia digest was the first in the NRC’s NUREG knowledge
management (NUREG/KM) series. One of the missions for NUREG/KMs isto preserve knowledge for future generations of the important historicalevents and research that have shaped the NRC’s regulatory programs. Thisknowledge management digest and supporting DVD contain the mostimportant documents that the NRC, the licensee, and other governmentorganizations issued following investigations and cleanup of the accident.
Although a few key documents have become available electronically, thisNUREG/KM marks the first time that the NRC has digitized these
historically important documents. On the DVD, the table of contents on thewelcome page provides access to these reports.
About Revision 1. This revision of NUREG/KM-0001 has evolved into twovolumes. This volume presents overviews of the accident: emergency
response, investigations, regulatory implications, and accident recovery.
This volume includes topics and documents provided on the original DVD
with new ones added. Supplement 1 expounds upon the technical details ofrecovery and cleanup activities: management and oversight, plantstabilization, worker protection, data acquisition and analysis, waste
management, decontamination, defueling, and after defueling. The
document collections in this supplement are derived from correspondence
between the utility and NRC, and from the results of research activities. The
accompanying DVDs for both volumes contain about 4,000 documents.
1

In addition to the large collection of documents, this volume provides three
NRC multimedia presentations, “The Accident at Three Mile Island, A
Look Back: Preserving the Institutional Memory after 30 Years,” “The35th Anniversary of the Three Mile Island Nuclear Power Plant Accidentof 1979: Working at TMI During and Following the Accident,” and“Moments in NRC History, Three Mile Island, March 28, 1979.”
This NUREG/KM does not fully convey the complete NRC experience inthe aftermath of the accident. Other interesting topics for future studies of
the TMI-2 accident include: legal lawsuits and actions; court proceedings,
including those at the U.S. Supreme Court; Atomic Safety and Licensing
Board proceedings; enforcement actions; the utility’s financial crisis;interactions with Congress; interactions with Federal, State, and local
government agencies; public outreach; the TMI Unit 1 restart; and oversightby the NRC’s Advisory Committee for Reactor Safeguards (ACRS).
How to Use this Digest. A few suggestions for navigating through thisNUREG/KM, and the many documents on the DVD, are provided at the endof this NUREG/KM (see the section on DVD Navigation andInterpretation). The historical documents provided on the DVD are forreference only, and are not official NRC records.

Shortly after the accident, NRC staff gathers in the NRC office trailer atThree Mile Island. Shown (front-left to right): Thomas Essig, George Smith,Richard Volmer, Frank Congel, Robert Bores (wearing hardhat), and
J. Philip Stohr (wearing vest).

22 The Accident
The sequence of certain events—equipment malfunctions, design-related
problems, and operator errors—led to a partial meltdown of the TMI-2
reactor core, resulting in a very small offsite release of radioactivity. In an
atmosphere of growing uncertainty about the condition of the plant, on themorning of March 30, 1979, Pennsylvania Governor Richard Thornburgh
advised people within a 5-mile radius of the plant to stay indoors. He also
advised pregnant women and preschool-age children to evacuate the area
within a 5-mile radius of TMI. By the close of the weekend of March 30
through April 1, 1979, TMI-2 was determined to be in a stable shutdown
condition. On Sunday, April 1, 1979, the President of the United States
James Earl “Jimmy” Carter, Jr., First Lady Rosalynn Carter, Governor
Thornburgh, and the NRC’s Harold Denton visited the damaged unit.
Within 2 weeks, the Governor’s precautionary advisory to pregnant womenand preschool-aged children was lifted.
While the utility and NRC were primarily charged with mitigating theconsequences of the accident through plant actions, reducing the effects ofoffsite radiological releases is the responsibility of State and Federal
agencies. The TMI accident initiated an institutional and public responsethat was unprecedented in the history of nuclear power in the United States.
Many organizations participated substantially in the response to this
accident, including approximately 24 Federal and 12 State agencies; themilitary; 27 counties of the Commonwealth of Pennsylvania; innumerable
local jurisdictions; public and private organizations; 4 bordering states; andseveral quasi-Federal organizations. Operational code name “Ivory
Purpose” was chosen for the purpose of citing accident support by militaryand other agencies. These institutions provided many kinds of support
services to the utility in evaluating the status of the plant, and in bringing
the plant to a safe-shutdown condition. Support was also provided to thestate in evaluating the extent of public hazards, preparing for possible
evacuation, and considering or preparing for the implementation of otherprotective actions.
The NRC played an active role as the regulator by responding to theaccident. A team began to form at the site with the arrival of the NRC’s
Region I inspectors during the morning of the first day of the accident, andcontinued to expand throughout the weekend with the arrival of engineers,scientists, and public affairs specialists from headquarters and other regional
offices. The incident response centers, located in the Region I office in Kingof Prussia, Pennsylvania, and at headquarters in Bethesda, Maryland, were3

staffed by NRC incident response teams during the morning of March 28.
Other NRC offices, such as State Programs, International Programs, Public
Affairs, and Administration, supported the NRC incident response effort.
The five commissioners, who provided the general policy that determined
the overall course of action that the NRC staff would take in response toincidents, were located at their downtown office on H Street in northwest
Washington, DC.
The NRC sponsored a Special Inquiry Group that was tasked withinvestigating the accident and reporting their findings in NUREG
Contractor Report 1250 (NUREG/CR-1250). Volume 1 of that reportcontains an informative and nontechnical discussion of the accident,
including onsite actions and offsite responses. Another good resource on theaccident is the main report by the President’s Commission on the Accident
at Three Mile Island. Additional volumes of both these reports provide
technical details of the accident and discussions of emergency actions by the
NRC, other Federal agencies, and State and local government offices. The
NRC’s training manual on reactor safety (NUREG/CR-6042, Section 2.2)
provides a technical summary of the accident, as well as an overview of theregulatory implications of the accident (Section 2.3).
The chronology of events can be found in all of the aforementioned
documents. Both “Backgrounder”, written by the NRC’s Office of Public
Affairs, and the NRC’s 1979 annual report (NUREG-0690), specifically
Chapter 2, contain additional nontechnical summaries of the accident;

Three Mile Island “trailer city” at the visitor center during the accident
response (helicopter pad upper left).

4

these, and other reports on the accident are provided on the accompanyingDVD.
One of many functions of the NRC incident response organization during
the accident was to notify appropriate internal offices and external agencies,
and keep them and the public informed. Document collections related to thefirst few weeks of the NRC response effort include the following:•

Preliminary notification (PN) reports, which were used by the NRC
Operations Center to communicate daily status of the accident (seeDVD folder, Response Preliminary Notices)•

Press releases issued by the NRC public affairs staff (see DVD folder,
Press Releases/Conferences)•

Transcripts of press conferences held by NRC emergency managers,
and many times, jointly with State executives (see DVD folder, Press
Releases/Conferences)•

International cables issued by the NRC international programs staff andused by State Department officials to keep foreign governments
informed of the accident (see DVD folder, International Cables)

NRC’s Harold Denton briefs the news media at the NRC press
center located at the basketball court in the Middletown
Borough Hall.

5During the course of the accident, the NRC commissioners (known
collectively as the “Commission”), met frequently to discuss the accident
and related matters. Because of their emergency nature, these meetings were
not open to the public. At the time of the accident, the five commissioners
were John Ahearne, Peter Bradford, Victor Gilinsky, Joseph Hendrie(chairman), and Richard Kennedy. Meetings were recorded and transcripts
were prepared in accordance with the Government in the Sunshine Act.
These transcripts were later released to the public and used in internal andexternal investigations of the accident. Notably, the Commission meetings
were sometimes held in locations other than where they normally would be,making the creation of complete and high-quality recordings difficult. As
such, these transcripts do not represent formal or official Commission
statements (see DVD folder, Commission/Operations Center Response).
Lessons from investigations of the accident led to vast improvements in
how the NRC, nuclear power plant utilities, and Federal and State agencies
respond to accidents. Revised NRC rules and guidance mandated utilities to

The NRC Executive Management Team at the NRC Operations Center
located in the East-West Towers Building, Bethesda, Maryland, during
the accident response. Shown (left-right): Lee Gossick (team directorand Executive Director for Operations), Edson Case (Deputy Director,
Office of Nuclear Reactor Regulation), Norman Moseley (Director,
Division of Reactor Operations Inspection), John Davis (Acting
Director, Office of Inspection and Enforcement), and James Sniezek(Director, Division of Fuel Facilities and Materials Safety Inspection).

6

upgrade their overall state of emergency preparedness for a wide range ofaccidents, including the integration of onsite and offsite emergency
preparedness. The newly established Federal Emergency Management
Agency (FEMA) consolidated offsite Federal emergency planning andresponse to radiological accidents. (Although Congress approved thePresident’s Reorganization Plan No. 3 of 1978 that created FEMA on
September 16, 1978, the transfer of Federal functions had not been
completed at the time of the TMI accident. In the reorganization, each Stateretained responsibility for protection of its citizens and the NRC retainedFederal jurisdiction over plant activities.)

A new state-of-the-art NRC Operations Center, located in the Fairmont
Building (also known as the Maryland National Bank Building) in Bethesda,
Maryland, was completed in early 1985 and remained in operation until the
NRC consolidated at the current White Flint complex in Rockville, Maryland,
during the summer of 1994. This first dedicated use operations center was
designed using lessons learned from the TMI-2 accident and human factors
principles to ensure seamless flow of information inside and outside thecenter. Shown is the Executive Team during the Saint Lucie Plant exercise on
March 20, 1991. Clockwise: Commissioner Kenneth Rogers (back to camera),
Brian Sheron (standing while briefing the team on reactor safety teamassessments), Edward Jordon (Director, Office of Analysis and Evaluation of
Operational Data), Themis Speis (Deputy Director, Office of Nuclear
Regulatory Research), Robert Bernaro (Director, Office of Nuclear Material
Safety and Safeguards), Thomas Murley (Director, Office of Nuclear Reactor
Regulation), and James Talyor (Executive Director for Operations).

7

In 1980, the NRC and FEMA signed memoranda of understanding to further
delineate responsibilities regarding emergency planning and activities at
NRC-licensed facilities. In the President’s Reorganization Plan No. 1
of 1980, the Commission’s emergency response functions were transferredto the NRC Chairman for defined emergencies. The Commission approved
the revised NRC Incident Response Plan in 1983, which, among numerous
improvements, established a site team that takes the agency’s lead for larger
responses. The Chairman could delegate specific authorities to the site teamleader during a defined emergency. The completion of TMI
recommendations relating to emergency preparedness and response aresummarized in NUREGs 0933 and 1355. Other documents specific to the
TMI-2 response, and generic to emergency preparedness for all
NRC-licensed activities, are provided on the DVD (see the DVD folders,
Other Response and NUREG Reports).

The pilot-operated relief valve on top of the pressurizer (seearrow) failed to close at the start of the accident. Steam leakedout through the stuck-open valve into the basement of thereactor building at a rate equivalent of some 220 gallons ofwater per minute, which continued for more than 2 hours and
20 minutes before operators realized that the valve had failed
to shut. This was a failure for which the TMI operators had
never been trained, and which was not described in theirwritten emergency procedures. This lack of preparation led toa misreading of the symptoms and mistaken responses thatwould uncover the reactor core.

8

3 Investigations and Lessons Learned
Two weeks after the accident, the President of the United States, Jimmy
Carter, appointed a 12-member Presidential Commission to investigate theaccident at Three Mile Island. This group, known as the “KemenyCommission,” conducted a comprehensive investigation of the accident andmade recommendations based upon their findings. Their final report wasissued to the President on October 30, 1979. Another 10 volumes
documented details of their investigation. The NRC published its initial
response to the Presidential Commission’s recommendations in
November 1979 as NUREG-0632 entitled, “NRC Views and Analysis of the
Recommendations of the President’s Commission on the Accident at Three
Mile Island.”The President responded to those reports in his statement on
December 7, 1979. By Executive Order 12202 of March 18, 1980, President
Carter established the Nuclear Oversight Committee for a short period oftime to report to him on the progress of implementing the approved
recommendations of the Kemeny Commission. A later report,
NUREG-1355, “Status of Recommendations of the President’s Commission
on the Accident at Three Mile Island—a 10-Year Review,” updated the
NRC’s initial response to include the status of the 44 recommendations
made by the Kemeny Commission over a 10-year period.
To help gain comprehensive insight into the accident, the NRC sponsoredboth internal and external investigations. In mid-June 1979, the NRC asked
the independent Special Inquiry Group to perform an investigation under the
directorship of the law firm of Rogovin, Stern, and Huge. Most of thepeople who assisted in the inquiry were drawn from the NRC staff, andOne highly publicized operating error was
the initial failure of emergency feedwater(EFW) flow to the steam generators by two
improperly closed EFW block valves. Oneof these tags obscured one of the block
valve indicator lights. The Special Inquiry
Group was not able to determine how theblock valves were closed; however, they
concluded that the 8-minute delay inrestoring EFW flow did not directly affectthe outcome of the accident. With thepressurizer relief valve stuck open and thehigh-pressure injection flow throttled, coredamage would have occurred anyway.

9carefully screened to avoid any conflicts of interest; a number of technicalconsultants were also engaged to assist in the inquiry. The Special Inquiry
Group provided a thorough analysis and assessment of the causes andimplications of the accident. As already noted, the NRC published this workin the four volumes of NUREG/CR-1250, “Three Mile Island, a Report to
the Commissioners and to the Public.”
Working internally, the NRC created a Lessons Learned Task Force in
May 1979. The NRC task force identified and evaluated safety concerns
originating from the TMI-2 accident that required licensing actions at othernuclear power plants. The NRC published the task force’s conclusions in
NUREG-0578, “TMI-2 Lessons Learned Task Force Status Report andShort-Term Recommendations,” and NUREG-0585, “TMI-2 Lessons
Learned Task Force Final Report.”
Many other groups, both internal and external to the NRC, also performed
separate investigations. These included the U.S. Congress and its General
Accounting Office; the Ad Hoc Dose Assessment Group, which comprised
various Federal agencies (see NUREG-0558); the NRC’s Advisory
Committee on Reactor Safeguards; the Bulletins and Orders Task Force of
the NRC’s Office of Nuclear Reactor Regulation (see NUREG-0645); the
NRC’s former Office of Inspection and Enforcement’s Special Review
Group (see NUREG-0616), Task Force on Lessons Learned (seeThe NRC Commissioners testifying before the U.S. Senate Subcommittee on
Nuclear Regulation for the Committee on Environment and Public Works.

10

NUREG-0600), and Division of Program Development and Appraisal (who
investigated information flow during the accident—see NUREG-0760); the
NRC’s Siting Task Force, which identified site location requirements fornuclear power plants; the NRC’s Emergency Preparedness Task Force; theStaff Panel on the Commission’s Determination of an Extraordinary
Nuclear Occurrence (see NUREG-0637); the NRC’s Office of Nuclear
Regulatory Research; and the NRC’s former Office of Standards
Development.
The DVD provides many of the key investigation reports on TMI (see DVD
folders, President's Commission, Rogovin Investigation, NRC
Investigations, and Other Investigations). Many of the aforementioned
investigation reports are summarized in NRC annual reports, primarily
NUREG-0690 (1979) and NUREG-0774 (1980).

11

TMI-2 Core End-State Configuration. In 1988, the NRC reported the final
state of the damaged TMI-2 reactor core, shown above. The accident was
terminated by reflooding of the core. This action did not immediately stop
further core melting, but it did prevent the core from melting through thereactor vessel.

12

4 Regulatory Actions
The NRC implemented a number of regulatory actions resulting frominvestigations and lessons learned reviews, and completed many more“spinoff” actions in the decades following the accident. The first wave ofactions that the NRC approved included orders to individual NRC licensees,and generic communications, such as bulletins and letters; these regulatory
tools were implemented in the days and months following the accident.
Once the various investigative groups had documented their findings, theCommission considered the recommendations. The NRC staff consolidated
all the recommendations that the Commission approved into NUREG-0737,“TMI Action Plan,” published in 1980. The plan included approximately
371 individual requirements. The NRC found that, of these, 13,863 action
plan items were applicable when reviewed against each specific licensed
nuclear power plant. Some requirements involved changes to the internal
NRC organization, processes, and practices.
A few requirements caused the Commission to issue policy statements andspecific changes to the NRC’s regulations through the rulemaking process.
Both of these long-term regulatory tools required extensive internal andexternal stakeholder involvement, and were completed during the 1980s.

NRC issued a requirement for nuclear power plants to have a simulation
facility appropriate to conduct operator licensing tests. All plants now have acertified plant-referenced simulator that demonstrates anticipated plant
responses to normal, transient, and accident conditions. Shown is one control
room simulator at the NRC Technical Training Center in Chattanooga,
Tennessee, used to train NRC inspectors and technical staff.

13

The NRC’s training manual on reactor safety, (NUREG/CR-6042,
Section 2.3), provided an overview of the regulatory implications of theaccident. NUREG-0933, “Resolution of Generic Safety Issues,”
documented the prioritization and closeout of the TMI Action Plan
requirements.
Generic Communications. Within 3 days of the accident, the NRC’s Officeof Inspection and Enforcement started to issue a series of bulletins
instructing all operating power plant licensees to take a number of
immediate actions to avoid repeating several of the events that occurred
during the accident and contributed significantly to its severity(Bulletins 79-05, -05A, -05B, -05C, -06, -06A, -06B, -06C, and -08). The
bulletins and resulting evaluations also substantially informed other staff
activities, such as those associated with the generic study efforts of theBulletins and Orders Task Force (NUREG-0645) and the Lessons Learned
Task Force (NUREG-0585). The NRC issued other types of genericcommunications, including generic letters (that transmitted information andusually required action or a response) and information notices (related toissues for which the licensees considered action appropriate). The DVD
provides most of the generic communications relevant to TMI-2 (see DVD
folder, Generic Communications).
TMI Action Plan. Each of the investigating groups organized theirrecommendations in a different way. These recommendations werecollected and transformed into discrete, scheduled tasks in NUREG-0660,“NRC Action Plan Developed as a Result of the TMI-2 Accident.” Thereport NUREG-0737, “Clarification of TMI Action Plan Requirements,”
documented the specific items from NUREG-0660 that the Commission
approved for implementation at nuclear power plants. In October 1980, the
NRC issued NUREG-0737 for implementation in Generic Letter 80-090.
This report comprised specific items and included additional information
about schedules, applicability, methods of implementation, submittal dates,
and clarification of technical positions. The Generic Safety Issues Program
prioritized and tracked the TMI Action Plan items detailed in NUREG-0660
and NUREG-0737. NUREG-0933, “Resolution of Generic Safety Issues,”
documented the closeout of action items.
The DVD provides the above NUREGs and other select NUREGs that wereassociated with the implementation and closeout of TMI Action Items (seeDVD folder, NUREG Reports).

14

Rulemaking and Regulatory Guides. In most cases, the NRC implemented
the TMI Action Plan items through the review of new licensee applications,and the imposition of confirmatory orders and specific license conditions,rather than through specific changes to the NRC’s regulations. In several
instances, implementation of the TMI Action Plan resulted in new or
modified regulations. These regulations, and a few others that could beconsidered relevant to the TMI accident, included the following: improved
emergency planning requirements in 1980; requirements related to hydrogen
control in Mark I and Mark II containments for boiling-water reactors(BWRs) in 1981; improved requirements for operations personnel andstaffing at nuclear power plants in 1983; requirements for event reportingin 1983; requirements related to hydrogen control in Mark III containments
for BWRs and ice condenser containments for pressurized-water reactors
in 1985; improved backfitting process for power reactors in 1985; improved
personnel dosimetry processing in 1987; improved requirements for
operator licensing in 1987; and mandated participation in the Emergency
Response Data System Program in 1991.

In support of the NRC Special Inquiry Group investigation, a mockup of theTMI-2 control room (above) was constructed by a contractor to study theextent to which factors incorporated within the discipline of human factors
engineering (e.g., man-machine interface design, procedures, manning, andtraining) were influential in causing or contributing to the course of theaccident. NRC required all licensees and applicants of new plants to conduct
similar detailed reviews to determine if their control rooms provided
satisfactory information to allow operators to prevent and cope with accidents.

15

In general, a regulatory guide (RG) describes one acceptable method for
implementing agency regulations. Regulatory guides are not substitutes forregulations and the NRC does not require that licensees comply with them.
Notable regulatory guides that the NRC revised or created during theimplementation of the TMI Action Plan include RG 1.8, “Qualification andTraining of Personnel for Nuclear Power Plants”; RG 1.97, “Criteria for
Accident Monitoring Instrumentation for Nuclear Power Plants”; RG 1.101,“Emergency Planning and Preparedness for Nuclear Power Reactors”; andRG 1.149, “Nuclear Power Plant Simulation Facilities for Use in Operator
Training and License Examinations.” NRC annual reports summarized
rulemakings and regulatory guides (see DVD folder, NRC Annual Reports,
in Supplement 1 to this NUREG/KM).
NRC Commission Policy Statements. Several policy statements that theCommission issued were directly or indirectly related to the TMI Accident.
A policy statement is not a regulation and does not impose specificregulatory requirements, but rather, provides the Commission’s rationale
and motivation for future regulatory positions. Two notable policy
statements that continue to have far-reaching regulatory applications include“Severe Reactor Accidents Regarding Future Designs and Existing Plants,”
issued in 1985 and “Safety Goals for the Operations of Nuclear Power
Plants,” issued in 1986. The former provided the basis for redirecting NRC
research programs and other regulatory programs; the latter provided thebasis for backfitting and regulatory analyses, and for the use of probabilistic
risk assessment in risk-informed decisions on plant-specific changes to theplant’s licensing basis. The DVD contains NRC Commission policy
statements relevant to TMI-2 (see DVD folder, Policy Statements).

To facilitate timely NRC responses,
more stringent notification
requirements were placed on
licensees in February 1980 with the
publication of 10 CFR 50.72 as an
immediately effective rule. The rule
required notification from licensees to
the NRC Operations Center within
one hour of emergencies and certain
significant events, via a dedicateddirect telephone “Hot Line.” Shown
is a 1985 photo of operations officers,
Chauncey Gould and Raymond Smith(back), at the new Operations Center
that opened in February 1985.

16

5 Research
The NRC’s approach to safety changed dramatically after the TMI-2
accident. The agency’s emphasis shifted from providing safety by relying
on the traditional design-basis approach, to relying on a multi-faceted
approach, which emphasized improved operations; human factors
considerations in control room and emergency procedures; realistic
performance of systems and containments under severe accident conditions;and probabilistic risk assessments to identify generic and plant-specificvulnerabilities. NRC research and development programs also reflected thischange.
After the accident, the scope and diversity of the NRC’s efforts in severe
accidents increased substantially. Some examples included allocating
additional resources to research and development activities, such as theconstruction of new experimental facilities; the development of analytical
tools; and, in general, the development of the information needed to gain
greater insight into severe accident behavior. Since the accident, the NRC,
DOE, the U.S. nuclear power industry, and international organizations havedeveloped a large body of information on severe accidents, including theirprobability; core-melt phenomenology; associated accident sequences; andthe effects of severe accidents on plant systems, components, and structures,

Closed-circuit video inspections of the reactor core revealed a rubble bed
approximately 5 feet below the normal location of the top of the fuelassemblies.

17especially those that provide barriers to fission product release to theatmosphere, such as the reactor containment structure.
Shortly after the accident, the DOE also supported an extensive research
program, known as the “TMI-2 Accident Evaluation Program,” to develop a
consistent understanding of the accident. The primary objective of the
program was to develop an understanding of core-damage progression in theupper core region; the heatup and the formation and growth of the molten
central region of the core; the relocation of approximately 19 metric tons ofdebris to the lower head; and the release of fission products to the reactor
vessel and containment.
Collaboration between the U.S. Government and nuclear industry
organizations also yielded important post-accident research. In 1980, fourorganizations—the General Public Utilities (GPU), Electric Power ResearchInstitute (EPRI), NRC, and DOE—formed a group known as “GEND,”
signing a coordination agreement to implement the TMI-2 Information andExamination Program. This program executed research and development
At left is a page recorded at
the NRC Operations Centeron the second day of theaccident showing temperature
readings that were measured
by plant technicians with ahandheld voltage meter on
the wires from reactor core
exit thermocouples. Thesethermocouples were
temporary installed tomeasure coolant temperatures
above the reactor fuel insupport of startup testing of
the new reactor. We now
know that many of thesetemperature readings were
measured at newly formed
false junctions located in the“liquefied fuel” regions of thecore. Today, all pressurizedwater reactors are required tohave redundant, qualified,Class 1E instrumentation forcore exit thermocouples, subcooling margin monitors, andreactor coolant inventory
monitors.

18

activities relating to the cleanup of TMI-2, and the study of the accident for
the enhancement of nuclear power safety and reliability. The group
documented the results of this program in a series of approximately
200 GEND and GEND-INF (informal) reports, as well as many othertechnical reports issued by the NRC, the DOE and its laboratories, EPRI,
and GPU.
A cooperation agreement was signed in April 1984 by the DOE and 17
Japan nuclear power organizations for a program of participation in the
DOE research and development programs relating to the
TMI-2 cleanup. This Japan-U.S. agreement provided informationexchanges, Japanese research staff at TMI-2 and DOE national laboratories,
and Japanese funding for research and development activities. A total of 43
engineers from 10 electric power companies, 3 reactor vendors, 2
engineering companies, the Nuclear Power Engineering Test Center(currently the Japan Atomic Energy Agency), and the Japan Atomic Energy
Research Institute (currently the Nuclear Regulation Authority) worked inalmost every area of the TMI-2 cleanup project during the 5-year period.

In August and September of 1983, the core topography system, designed andbuilt by DOE, was used to develop an ultrasonic profile of the void area in theupper reactor core region. The data and information obtained included theradial and axial extent of the reactor core cavity, the location of supported andunsupported fuel assembly end-fittings, and the location of the core cavity
boundary with respect to structurally intact fuel assemblies. The analysis of
this data supported upper plenum lift and defueling operations. Shown is the
topographic model of the cavity in the upper core region based on thisultrasonic profile. This model is currently located at NRC Headquarters.

19

Supplement 1 of the NUREG/KM provides most of the NRC and DOE
reports and presentation papers, which documented research anddevelopment activities relating to the TMI-2 accident and its uniquerecovery and cleanup. GEND reports are provided in Supplement 1. NRC
annual reports provided summaries of NRC research activities (see DVD-2
folder NRC Annual Reports).

Numerous manual and hydraulically powered long-handled tools were used toperform a variety of functions, such as pulling, grappling, cutting, scooping,and breaking up the core debris. These tools were used to load debris into fuelcanisters positioned underwater in the reactor vessel. Later, a core boringmachine (lower right) was used to break apart once liquefied materials.

20

6 Plant Recovery and Cleanup
By the close of the weekend of March 30 through April 1, 1979, TMI-2 wasdetermined to be in a stable shutdown condition. Within 2 weeks, theGovernor’s precautionary advisory to pregnant women and preschool-aged
children to evacuate the area within a 5-mile radius of TMI was lifted.
Within 1 month, the reactor was placed in natural circulation, with decay
heat flowing to the condenser and out of the cooling towers. The purging ofradioactive krypton gas from the reactor-building atmosphere, followed by
the first entry into the reactor building by two utility engineers, wasaccomplished after the first anniversary of the accident. Shortly before thesecond anniversary, the reactor was placed in loss-to-ambient cooling mode,in which heat losses are transferred from component and piping surfaces
into the reactor building’s ambient environment and out through the reactor
building’s fan coolers.
The reactor vessel head was removed in 1985, while the removal of loose
fuel debris from the reactor vessel began later that year, and was completed
in 5 years. Workers used numerous manual and hydraulically-powered,long-handled tools to perform a variety of functions, such as pulling,grappling, cutting, scooping, and breaking up the core debris. In 1986,
7 years after the accident, a special core-sampling drilling rig was used to

The first entry into the reactor building occurred on July 23, 1980 (shown).
Heavy-duty outerwear provided protection from high-energy, low-penetration
beta radiation.

21

reveal the extent of the hard crust layer of the damaged core. Between
1986 and 1990, the DOE shipped the fuel debris by rail to the DOE site at
the Idaho National Engineering Laboratory (currently called Idaho National
Laboratory), and placed the debris in wet pool storage for study andsafekeeping. The evaporation of 2.3 million gallons of slightlycontaminated, accident-generated water at TMI was conducted over a 2- to
3-year period, and completed in 1993.
In late 1993, TMI-2 was placed in NRC-approved, post-defueling,
monitored storage, a passive monitored state in which the plant will remain
until both units are decommissioned simultaneously. From 2000 to 2001,
the fuel debris was moved into NRC-approved aboveground dry storage at a
DOE facility to await final disposal.
NRC Actions at TMI. The NRC played an active role as the regulator, firstby responding to the accident, and then by approving and overseeing
recovery activities by the licensee and its contractors. With the arrival of the
NRC’s Region I inspectors during the first day of the accident, a team began
to form and continued to expand throughout the weekend with the arrival ofengineers, scientists, and public affairs specialists from headquarters andother regional offices. Early in 1980, the NRC established the TMI Program

Water level in the reactor building basement reached the first stairwell
landing, indicating about 8 feet of water. The submerged demineralizer system
or “SDS” was designed and installed to cleanup the 700,000 gallons of highly
contaminated basement water. The SDS started operations in September 1981
after NRC approval and completed processing basement water in May 1982.

22

Office (TMIPO) within the NRC’s Office of Nuclear Reactor Regulation toprovide overall direction for the TMI-2 cleanup operations and inspections(see NUREG-0698). About 30 NRC employees staffed the onsite TMIPO
office during the first few years. NRC’s regulatory responsibilities inrecovery operations included reviewing and approving the licensee’s
proposals for recovery actions, overseeing the licensee’s implementation of
approved activities, coordinating with other Federal and State government
agencies on their activities in the recovery, and informing local officials andthe public about the status of the recovery operation.
Important NRC actions during TMI-2 recovery are summarized below anddiscussed in detail in Supplement 1 to this NUREG/KM.
•

issuance of the environmental assessment (NUREG-0591) andCommission order to use the EPICOR II system to decontaminate
intermediate-level radioactive accident water in the auxiliary building in
October 1979•

creation of the NRC Special Panel on TMI-2 Radiation Protection
Program in September 1979 to provide an independent review of theWorkers perform defueling operations from a shielded defueling work
platform, which was located 9 feet above the reactor vessel flange. The
platform had a rotating surface with 6-inch steel plates and a diagonal slit foraccess into the reactor vessel for removing debris.

23licensee’s existing and planned radiation protection program during
recovery and cleanup (NUREG-0640)•

issuance of the Commission order to implement the TMI-2 recovery
technical specifications in February 1980 (NUREG-0647)•

issuance of a research coordination agreement with the DOE, EPRI, andthe licensee in March 1980 to jointly sponsor and participate in the TMIInformation and Examination Program, and to obtain valuable
information from the accident•

approval by the Commission in April 1980 to allow small radioactive
releases for the purpose of data gathering and maintenance operations(SECY-80-175)•

issuance of the environmental assessment (NUREG-0662) andCommission order to purge radioactive krypton gas from the reactor
building atmosphere in June 1980

The first piece of core debris was placed into the defuelingcanister in November 1985 (shown). The long-handled vice-grip
tool was clamped onto an upper end fitting of a partial fuelelement. A long-handled tamping tool (upper left) was used totap the piece into the canister.
24

•issuance of the NRC action plan for cleanup operations in July 1980
(NUREG-0698)•

issuance of the draft Programmatic Environmental Impact Statement(NUREG-0683) for public comment in August 1980 and
implementation in February 1981•

creation of the public Advisory Panel for the Decontamination of Three
Mile Island in November 1980 (see NUREG/CR-6252)•

issuance of the Commission Policy Statement endorsing theProgrammatic Environmental Impact Statement in May 1981•

issuance of the safety evaluation report and order to use the submerged
demineralizer system to process the highly-contaminated,
accident-generated water in the reactor building sump and reactor
coolant system in June 1981 (NUREG-0796)

The NRC issued certificates of compliance to the DOE in April 1986 forcasks used to ship fuel debris by rail to the Idaho National Engineering
Laboratory (INEL) for research and temporary storage. Each cask
contained up to seven defueling canisters. Each rail shipment included up to
three cask rail cars. A total of 342 defueling canisters were shipped to INEL
in 22 trips between 1986 and 1990.

25

•issuance of a March 1982 amendment to the memorandum of
understanding with the DOE to accept the entire reactor core andhighly-radioactive solid waste for research and long-term storage (seeAppendix A to Revision 2 of NUREG-0698)•

approval, in November 1983, of the licensee’s safety evaluation for the
refurbishment and use of the reactor building polar crane for defueling
operations•

issuance of Supplement 1 to the Final Programmatic Environmental
Statement (NUREG-0683) on dealing with occupational radiation dosein October 1984•

issuance of certificates of compliance in April 1986 for three shipping
casks to be used for shipment of fuel debris to DOE by rail•

issuance of Supplements 2 and 3 to the Final Programmatic
Environmental Statement (NUREG-0683) on the final disposal of
2.3 million gallons of slightly-contaminated, accident-generated waterin June 1987, and dealing with post-defueling monitored storage andsubsequent cleanup in August 1989•

approval in September 1989 to use the evaporator for the final disposalof 2 million gallons of accident-generated water

TMI-2 Independent Spent Fuel Storage Installation located at DOE’s Idaho
National Laboratory for interim storage of the TMI-2 core debris.

26

•issuance of two amendments to the facility operating license in
September and December 1993 to issue a possession-only license andissue technical specifications for post-defueling monitored storage

The NRC Headquarters wrapped up onsite involvement at TMI-2 by thetime that the agency terminated the TMI-2 Project Directorate in
February 1988. The NRC’s TMI resident inspector office took over theinspection program for TMI-2 and a headquarters project directorate
assumed responsibility for the technical review and project management
functions. In September 1993, the NRC approved “post-defueling monitored
storage” at TMI-2 and associated license conditions and technicalspecifications. The last meeting (78th overall) of the 10-member public
Advisory Panel for the Decontamination of Three Mile Island Unit 2 washeld in September 1993 (see NUREG/CR-6252 for lessons learned). See
Supplement 1 to this NUREG/KM for more documents covering recovery
and cleanup activities.
Timeline. The timeline feature on the DVD provides a summarized
chronology of key recovery milestones and NRC actions. Users may read ashort description of many of the actions by clicking on the text of thetimeline in the interactive window of the DVD.
Status Reports. Several document collections in Supplement 1 to thisNUREG/KM provide informative daily, weekly, and annual summaries of
TMI-2 recovery and cleanup experiences. These status documents, which
are related to topics discussed in all volumes and sections of thisNUREG/KM, are provided in the following document collections in
Supplement 1:•

NRC TMI Program Office (TMIPO) weekly status reports (see DVD
folder TMI Program Office Weekly Status Reports)•

preliminary notification reports—an early notice of an event of possible
safety or public interest significance issued by TMIPO or other NRC
offices (see DVD folder NRC Preliminary Notifications)•

NRC annual reports to the President of the United States (see DVD
folder NRC Annual Reports)•

DOE reports, such as annual and lessons-learned reports, and periodical
publications (see DVD folder DOE/National Laboratory Status Reports)27

•

licensee event reports—a written report of a reportable event submitted
by the licensee to the NRC (see DVD folder Licensee Event Reports)•

licensee summary reports required by regulatory requirements (seeDVD folder GPU Status Reports)

NRC’s Harold Denton, Governor Richard Thornburgh, President Jimmy
Carter, and Rosalynn Carter tour the TMI-2 control room on April 1, 1979.

28

7 Retrospectives
30th Anniversary. For the 30th anniversary of the TMI-2 accident, the
NRC’s Office of Nuclear Regulatory Research (RES) hosted a special
all-day event entitled, “The Accident at Three Mile Island,
30th Anniversary, A Look Back: Preserving the Institutional Memory.” Theevent featured several presentations, including an overview of the accident
by Brian Sheron, Director of the NRC’s Office of Nuclear Regulatory
Research; perspectives from TMI-2 Reactor Operator Edward Frederick;lessons learned from TMI-2 by Gary Holahan, Deputy Director of the
NRC’s Office of New Reactors, and former member of the TMI-2 Lessons
Learned Task Force; and an historical perspective by NRC Historian
Samuel Walker.
Following the individual presentations, the NRC hosted a panel discussion
titled “Remembering the Accident.” The panel included a distinguishedgroup, all of whom made key decisions during the accident: Richard
Thornburgh, former Governor of the State of Pennsylvania; Harold Denton,
former Director of the NRC’s Office of Nuclear Reactor Regulation and thelead Federal onsite manager; and Jessica Mathews, former assistant to
President Jimmy Carter.

A press conference during the early days of the accident with
Pennsylvania Governor Richard Thornburgh (right) and the
NRC’s Harold Denton.

29

In April 1984, a comprehensive video mapping of the upper reactor coreregion between the plenum and rubble bed was completed. Video snapshots
were assembled into a mosaic panoramic view of the rubble bed and core
periphery. Videos of the rubble bed showed broken fuel rods scattered around,
fuel rod internal springs, intact fuel pellets, control-rod assembly end
couplings, and partially intact fuel assemblies around the periphery of thereactor core region. The video also showed unsupported partial fuelassemblies hanging from the underside of the upper plenum grid section
which had to be removed before plenum lifting. This map supported planningof defueling operations and eventually the removal of fuel debris.

30

35th Anniversary. For the 35th anniversary of the TMI-2 accident, RES
hosted a special NRC research seminar event entitled, “The35th Anniversary of the Three Mile Island Nuclear Power Plant Accidentof 1979: Working at TMI During and Following the Accident.” The seminarfeatured a presentation by Mr. Gordon Skillman, a current member of
NRC’s Advisory Committee on Reactor Safeguards, who was an immediate
responder to the TMI-2 accident. As an employee of Babcock and Wilcox
during and after the accident, he served for 7 years of the stabilization andcleanup of TMI-2 as recovery support engineering manager and later as thedefueling manager.
The presentation covered Mr. Skillman’s firsthand experiences whileworking on technical issues involving plant and reactor core stabilization,
accident water cleanup, and early defueling the damaged core. Mr. Skillman
shared his personal experiences while living in a nearby community andworking closely with people from the utility, many contractors, the NRC,
the DOE, national laboratories, and Pennsylvania’s and Maryland’s
environmental agencies.
Moments in NRC History. As part of the video series on NRC history, theOffice of the Secretary and the Office of Public Affairs prepared a video
entitled, “Moments in NRC History, Three Mile Island, March 28, 1979.”
The video features a short documentary by the NRC’s historian, Dr. Thomas
Wellock. Dr. Wellock studies nuclear power’s history for its relevance to
the NRC today and to capture important insights for future generations. This
video recounts the plant response during the accident, the emergency
response to the accident, improvements to plant safety, and current status of
the plant.
The DVD provides a multimedia presentation of these events (see DVD
folders, 30th Anniversary Seminar, 35th Anniversary Seminar, andMoments in NRC History).

31

32

8 DVD Navigation and Interpretation
This knowledge management guide is an HTML-based collection of
information, documents, videos, and photos related to the 1979 accident at
the Three Mile Island nuclear power plant. This interactive feature isprovided on the DVD to help you navigate through the historical records.
Refer to the “Readme” file located on any DVD for viewing instructions.
Navigation•

Main welcome page. From the welcome page, you can navigate thedifferent sections of the guide using the blue tabs from the menu on theleft side of the page. Each tab is linked to a page that contains one ormore subtabs that appear to the right of the tab. Each tab corresponds toa document collection and each subtab links to a folder of documents.
This interactive feature will prompt you to load the appropriate DVD toretrieve the document, if necessary. Additionally, there is a photogallery, interactive timeline, and a document index (green tab). You
may also click on the text box on the timeline for a short description.

•

Document retrieval. Documents can be accessed from the document
page (see figure below) linked to the subtab. Next to each document is a
hyperlink which will display the associated document, photo, or video.
Because the document collection spans several DVDs, you may beprompted to insert a different DVD as you navigate the guide. A sorting
feature is provide on select columns on the document page.

•

Document searches. A simple keyword search feature is provided on
the welcome page and each document page. A search is applied to a listof all documents on all DVDs in this NUREG/KM. This featuresearches words in the file name.

•

Document lists. Several convenient lists of documents on the DVD canbe viewed from the “Document Folder Index” tab. These lists are also
provided in spreadsheet format in the “Common” folder on the DVD(located in the “Documents” folder). A list of more than 25,000 TMI-2
records in the Public Legacy Library is included in the spreadsheet.

•

Alternative. Documents are titled and arranged in topical folders on the
DVD (located in the "Documents" folder) to provide a usable alternative
to the interactive guide. The document can be accessed directly on the
DVD using a file explorer.
33

Things to Keep in Mind•

Legacy documents. Many of the documents on the DVD are historicalin nature and might contain information that is obsolete or supersededby current regulations and research results. The historical documents
provided on the DVD are for historical reference only and are notofficial NRC records. Please refer to the NRC’s public website(http://www.nrc.gov) for current information on regulations, policy
statements, regulatory guidelines, regulatory processes, and research
results.

•

Units of measure. The unit of measure (in English units or theInternational System of Units) that was used in the original source
document was used in this digest. A conversion chart is provided on theback cover.

•Abbreviations. A small set of abbreviations was used throughout thisreport in order to improve readability: ALARA (as low as reasonably
achievable), CFR (U.S. Code of Federal Regulations), DOE, DVD,
EPRI, GEND, GPU, INEL, NRC, NUREG, NUREG/CR, NUREG/KM,
PDMS, and TMI-2. Abbreviations that were less frequently repeated in
the report were spelled out at the beginning of each subsection orparagraph that contained them.

•

Recovery vs. cleanup. The term “recovery” is used in this NUREG/KM
to mean actions taken to keep the plant in a stable condition and toprevent the inadvertent release of radioactivity. The term “cleanup” isused to mean actions taken to decontaminate and defuel the plant anddispose of radioactive waste. These two terms are often usedinterchangeably for certain actions.

•

EPRI and GPU documents. Documents generated by EPRI and GPU
are generally not provided on the DVD unless the documents were
submitted to the NRC or funded by DOE.

•

“GPU” and “licensee.” Unless otherwise noted, the GPU Corporationand its subsidiaries (including GPU Service Corporation, GPU Nuclear
Corporation, and Metropolitan Edison Company) are referred tocollectively in a historical context as “GPU” or the “licensee” in the textof this NUREG/KM and document filenames.

34•Document accession number. Each document and each enclosure of adocument that was cataloged in the Agencywide Documents Access andManagement System (ADAMS) Public Legacy Library was assigned aunique accession number. This number can be found on the first page ofeach document. Each enclosure to a transmittal letter was typicallyassigned its own accession number.

•

Document filename. The filenames used on the DVD typically containthe date of the document (generally the date of the transmittal letter);originating organization (e.g., NRC or GPU); document type(e.g., safety evaluation or system description); short title; document
revision, if any; and reference date of previous correspondence, if any.
Technical reports by the NRC (e.g., NUREGs), DOE, and national
laboratories start with the report’s identification number, short title, andyear and month issued. See examples below.
(1990-01-18) GPU, Defueling Completion Report, Rev. 3 (re 08-18, 10-09-1989)
NUREG-0698, Rev. 2, NRC Plan for Cleanup Operations at TMI-2 (1984-03)•

Documents, photographs, and diagrams in this NUREG/KM and DVD
were copied from the best available (surviving) sources. Photographs
were generally taken by GPU and DOE contractors.

A typical document page listing the contents of a document folder. Columns
can be sorted. Keywords in document file names can be searched. The
hyperlink directs you to the document, photo, or video.

35

The certificate of appreation given to NRC staff who contributed to the
NRC’s response to the accident. By the end of the second week, over 200
NRC staff were badged for site access, or about 10 percent of all external
responders at TMI. Names of NRC staff who responded to the accident at
the TMI site and offsite response centers are discsussed in the Rogovinreport (see NUREG/CR-1250, Volume 2, Part III, Appendix III.2).

36

9 Contributions to the Main Report(NUREG/KM-0001, Overview)
Knowledge
Harold Denton
Edward Frederick
Gary Holahan
Don Marksberry
Jessica Mathews
Brian Sheron
Gordon Skillman
Governor Richard Thornburgh
J. Samuel Walker
Thomas Wellock
Management
Don Marksberry
Felix Gonzalez
Kenneth Hamburger
Theodore Smith
Anita Aikins-Afful
Robert Norman
David Aird
Ian Gifford
Brian McGrattan
Amy Bonaccorso
Tom KardarasMark Henry Salley
andThe NRC Print Shop and Publications Staff
Document Collections
NRC’s Agencywide Documents Access and Management System
Publications Branch of the NRC’s Office of Administration
NRC’s Office of the Secretary
U.S. Department of Energy
Idaho National Laboratory
Dickinson College Community Studies Center
Pennsylvania State University Engineering Library
National Archives and Records Administration
37

38

CONVERSIONS
Radiation Dose
1 mrem (1 millirem, 10-3) = *10 microsieverts (10 µSv, 10-5)
100 mrem = *1 millisievert (1 MSv)
1 rem = *10 mSv
100 rem = *1 Sv
Radioactive Concentration
27 picocuries (27 pCi, 2.7 × 10-11) = *1 becquerel (1 Bq)
1 millicurie (1 mCi, 0.001) = *37 megabecquerels (37 MBq, 3.7 × 107)
1 curie (1 Ci) = *37 gigabecquerels (37 GBq, 3.7 × 1010)
Radiation Absorbed Energy
1 roentgen = *0.877 rad = *0.00877 Gy
100 rad = *1 gray (Gy)
Length1 inch (in) = *2.54 centimeters (cm)
1 foot (ft) = 0.3048 meter (m)Volume and Weight
1 gallon (gal) = 3.7854 liters (l)1 pound (lb) = 0.4536 kilograms (kg)
1 ton (U.S.) = *2000 lb = 907.1847 kg
Pressure
1 pound per square inch (psi) = 6.8948 kilopascals (kPa)
1 atmosphere (atm) = *101.325 kPa
Temperature
Degrees Celsius (°C) = 5/9 × (°F - 32)
Degrees Fahrenheit (°F) = (9/5 × °C) + 32
* Exact conversion factors

NUREG/KM-0001, Revision 1
June 2016