The Three Mile Island Accident. Diagnosis and Prognosis

305 Pages·1986·28.714 MB·English

by  L. M. Toth, A. P. Malinauskas, G. R. Eidam, and H. M. Burton (Eds.)

The Three Mile Island Accident
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In The Three Mile Island Accident; Toth, L., el al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
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In The Three Mile Island Accident; Toth, L., el al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
ACS SYMPOSIUM SERIES 293
The Three Mile Island Accident
Diagnosis and Prognosis
L. M. Toth, EDITOR
Oak Ridge National Laboratory
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3.f A. P. Malinauskas, EDITOR
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1/b G. R. Eidam, EDITOR
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1 Bechtel National, Inc.
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6 | d H. M. Burton, EDITOR
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19 EG&G Idaho, Inc.
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e: Developed from a symposium sponsored by
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D the Division of Nuclear Chemistry and Technology
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ati at the 189th Meeting
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Miami Beach, Florida,
April 28-May 3, 1985
American Chemical Society, Washington, D.C. 1986
In The Three Mile Island Accident; Toth, L., el al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
Library of Congress Cataloging in Publication Data
The Three Mile Island accident.
(ACS symposium series. ISSN 0097-6156; 293)
"Developed from a symposium sponsored by the
Division of Nuclear Chemistry and Technology at the
189th Meeting of the American Chemical Society.
1 Miami Beach, Florida, April 28 May 3, 1985."
0
w0 Includes bibliographies and index.
3.f I. Three Mile Island Nuclear Power Plant (Pa.)—
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2 Congresses. 2. Nuclear power plants—Pennsylvania—
6-0 Accidents—Congresses.
8
9 I. Toth. L. M. (Louis McKenna), 1941-
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k- II. American Chemical Society. Division of Nuclear
1/b Chemistry and Technology. III. American Chemical
2 Society. Meeting (189th: 1985: Miami Beach. Fla.)
10 IV. Series.
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oi: 1 ITSKB N13 405 .8H43127 T0459 48 0 1986 363.1'79 85-26852
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ate: Copyright © 1986
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n American Chemical Society
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In The Three Mile Island Accident; Toth, L., el al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
ACS Symposium Series
M. Joan Comstock, Series Editor
1 Advisory Board
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3.f Harvey W. Blanch Donald E. Moreland
29 University of California—Berkeley USDA, Agricultural Research Service
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9 Alan Elzerman W. H. Norton
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bk- Clemson University J. Τ. Baker Chemical Company
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1 John W. Finley James C. Randall
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oi: 1 Nabisco Brands, Inc. Exxon Chemical Company
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6 | Marye Anne Fox W. D. Shults
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19 The University of Texas—Austin Oak Ridge National Laboratory
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er Martin L. Gorbaty Geoffrey K. Smith
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m Exxon Research and Engineering Co. Rohm & Haas Co.
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e: Roland F. Hirsch Charles S. Tuesday
Dat U.S. Department of Energy General Motors Research Laboratory
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bli Consultant, Computers & National Institute of
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Vincent D. McGinniss C. Grant Willson
Battelle Columbus Laboratories IBM Research Department
In The Three Mile Island Accident; Toth, L., el al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
FOREWORD
The ACS SYMPOSIUM SERIES was founded in 1974 to provide a
medium for publishing symposia quickly in book form. The
format of the Series parallels that of the continuing ADVANCES
IN CHEMISTRY SERIES except that, in order to save time, the
1 papers are not typeset but are reproduced as they are submitted
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w by the authors in camera-ready form. Papers are reviewed under
3.f the supervision of the Editors with the assistance of the Series
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0 Advisory Board and are selected to maintain the integrity of the
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98 symposia; however, verbatim reproductions of previously pub­
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In The Three Mile Island Accident; Toth, L., el al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
PREFACE
THE THREE MILE ISLAND ACCIDENT occurred on March 29, 1979. The
decision to hold a symposium on the TMI accident aftermath was reached
when it was realized that enough information had been gathered during the
past 6 years to provide a fairly complete picture of the damage and of the
activities required for eventual recovery. The scientific community and the
1 public are generally unaware of these activities; thus a review at this time
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pr0 seems appropriate.
3. The symposium was organized into three sessions: the first dealt with a
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2
0 description of the accident, the second focused on the chemical aspects
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98 involved, and the third addressed the strategy and progress made toward
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k- recovery. The symposium was intended to focus on these three subjects and
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21/ leave the environmental considerations to future meetings and reports.
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0.1 Although it might appear shortsighted to exclude the environmental impact,
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oi: the exclusion was considered necessary in order to maintain the focus we
d sought.
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8 This endeavor would not have been successful without the support and
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3, cooperation of many individuals and organizations. First of all, Ray G.
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er Wymer (Oak Ridge National Laboratory) and Richard W. Hoff (Lawrence
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m Livermore National Laboratory) should be recognized for the initial impetus
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ec on this project. Next, my coorganizers, Tony Malinauskas (Oak Ridge
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e: National Laboratory), Greg R. Eidam (Bechtel National, Inc.), and Harold
Dat Burton (EG&G) must be identified as the muscle that produced the proper
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o program and the involvement of the best experts on the subjects. Especially
cati significant has been the cooperation of the GPU Nuclear Corporation
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details. As a result, the papers presented here are from some of the key
persons involved in the cleanup operation.

L. M. TOTH
Oak Ridge National Laboratory
Oak Ridge, TN 37831
September 12, 1985
IX
In The Three Mile Island Accident; Toth, L., el al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
1
Description of the Accident
Garry R. Thomas
Safety Technology Department, Nuclear Power Division, Electric Power Research
Institute, Palo Alto, CA 94303
1 The TMI-2 accident occurred in March 1979. The acci
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0 dent started with a simple and fairly common steam
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3.c power plant failure--loss of feedwater to the steam
29 generators. Because of a combination of design, train
6-0 ing, regulatory policies, mechanical failures and
98 human error, the accident progressed to the point
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1/b age in large nuclear power reactors.
02 Core temperatures locally reached UO fuel lique
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0. faction (metallic solution with Zr) and even fuel melt
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doi: Z(3i8rc0a0l-o5y1 0c0l°aFd).d inEg xotxenidsaivteio nfi sasniodn e mpbrorditutlcetm reenlte aosce and
6 | curred. At least the upper 1/2 of the core fractured
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9 and crumbled upon quenching. The lower central por
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3, tion of the core apparently had a delayed heatup and
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er then portions of it collapsed into the reactor vessel
b lower head. The lower outer portion of the core may
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e be relatively undamaged. Outside of the core bound
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De ary, only those steel components directly above and
e: adjacent to the core (≤1 foot) are known to have suf
Dat fered significant damage (localized oxidation and
n melting). Other portions of the primary system out
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ati side of the reactor vessel apparently had little
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Pu The demonstrated coolability of the severely dam

aged TMI-2 core, once adequate water injection began,
was one of the most substantial and important results
of the TMI-2 accident.
Early on the morning of March 28, 1979, at almost exactly 4:00 am,
the 880-MWe Three Mile Island-Unit 2 (TMI-2) pressurized water reac­
tor (PWR), which was operating at nearly full power (98% full power
or -2720 MWth), had a loss of feedwater event. What should have been
a normal sequence of events responding to the loss of feedwater and
resulting in an uneventful shutdown of the plant did not proceed as
planned—and the reactor core ultimately was badly damaged. This
paper presents both a brief history of the important aspects of the
0097^156/86/0293-^2$07,O0/O
© 1986 American Chemical Society
In The Three Mile Island Accident; Toth, L., el al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
1. THOMAS Description of the Accident 3
accident that affected the core damage (1-3) and a summary of the
actual damage as currently known.
Background
A PWR such as the Babcock and Wilcox designed TMI-2 plant has separ
ate primary coolant and secondary coolant systems. The primary
system of a PWR (Figure 1 for the TMI-2 system) is operated at a
sufficiently high pressure—2200 psia (15.2 MPa) for TMI-2—to pre
vent reaching a bulk saturated water temperature and net steam forma
tion during any normal operation. At full power, the pressurized
water flows upward through the core at a rate of -1.38 x 10° lbm/h
(-1.74 x 104 kg/sec) and is heated from 557°F (565 K) to 611°F
(595 K). The water exits the core and reactor vessel and enters the
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0 tube side of the steam generators via large vessel outlet pipes,
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h which at TMI-2 are called the candy-cane hot legs because of their
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3. characteristic shape (Figure 1). At TMI-2, there are two steam gen
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02 erators with once-through flow on the primary side, as shown for a
86- single generator in Figure 1. Each steam generator is fed by one hot
19 leg and is emptied by two cold legs which return water to the reactor
bk- vessel under the driving head of main coolant pumps.
21/ Steam to drive the turbine-generator unit is formed in the sec
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1 ondary system in the shell side of the steam generators. A complete
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1 TMI-2 system schematic is shown in Figure 2, again with only one of
oi: two loops (the A loop) shown. The A loop contains the pressurizer
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6 | and its relief valve that play a major part in the TMI-2 accident.
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3, 1 The Accident
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er With the loss of feedwater supply to the main feedwater pumps, caused
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m by a condensate pump trip, the main feedwater pumps also trip. (See
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ec Figure 2 for locations of these and following reactor system compo
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e: nents.) The system, still responding normally, trips the turbine
at generator and starts the auxiliary feedwater pumps in an effort to
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n maintain secondary side heat removal in the steam generators. This
atio is required for maintaining proper primary system temperatures and
c pressure until the reactor can be scramed (nuclear power shutdown)
ubli and the reactor system placed in stable standby conditions.
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However, in spite of starting the auxiliary feedwater pumps, no
feedwater supply reaches the steam generators. Block valves in 1ine
with the auxiliary feedwater pumps had been closed earlier as part of
the requirements of a recently-completed test operation of the sys
tem—but the valves had inadvertently remained closed after test com
pletion; hence, no feedwater can reach the steam generators.
We are still in the first few seconds of the accident. Loss of
ability for the primary system to dump its nearly full power load re
sults in an increase in water volume in the primary system because of
heating. This increase is seen directly as a level increase in the
pressurizer located on the A loop. The pressurizer, normally about
half full during ful1 power operation, acts as both the primary
system accumulator plus controller of system pressure. It controls
pressure by maintaining the proper pressure limits in its steam-
filied upper region through a combination of electrical heaters in
its lower water-filled portion and spray cooling in its upper
portion.
In The Three Mile Island Accident; Toth, L., el al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
4 THE THREE MILE ISLAND ACCIDENT
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ec Figure 1. Schematic of the TMI-2 primary system (only one of two
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e: nearly identical loops shown). Reproduced with permission from
at Ref. 1. Copyright 1980, Electric Power Research Institute.
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In The Three Mile Island Accident; Toth, L., el al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1986.