Public
Opinion and the Accident at Three Mile Island
Eddie
Papalia
Geology
206
ABSTRACT
Several
months ago approximately fifty students at Haverford and Bryn
Mawr Colleges
were asked to rate different sources of energy, including nuclear power. While these students did recognize some of
the benefits of nuclear power, most were clearly more concerned with its risks,
and consequently ranked this source of power relatively low in comparison to
other energy sources. Some of the
surveyed even cited, verbally, the occurrences at Three Mile Island
in the spring of 1979 as proof that we should be worried. At the same time, recent surveys, conducted
on a national level, suggest growing support for nuclear power. This paper has several objectives. First, it seeks to assess how attitudes
regarding nuclear power, specifically in the United
States, have changed over the decades. How did people feel about nuclear power
before the events that occurred at Three Mile Island in
1979, for example? Furthermore, how do Americans
today feel about this source of energy? This
paper concludes that public opinion has varied throughout the years and
explores the reasons for this variation.
This paper then looks to investigate the accident that occurred at unit
two of the Three Mile Island nuclear generating station
in the spring of 1979 in an attempt to assess whether an accident like the one
that occurred at Three Mile Island could happen
again. It concludes that the likelihood
of such an accident is extremely low.
INTRODUCTION
At
one point, nuclear power looked to be the future. Not only could it satisfy American’s growing
demands for electricity, but it could produce this electricity cleanly and
perhaps eventually at a very low cost.
As time progressed, the public became more aware of the fallbacks of
nuclear power, particularly its risks.
Some even demanded an end to the construction of new plants. At the same time, although vehemently denied
by some in the industry, there was mounting evidence that safety systems might
not work as designed. On March 28, 1979, the events at Three
Mile Island nearly confirmed nuclear critics’ worst fears. The plant experienced a loss of coolant
accident and a partial meltdown as a result of equipment malfunction and
personnel error, but safety features prevented the release of significant
amounts of radiation. Although the
events that occurred at Three Mile Island are real life
examples of the risks associated with the use of nuclear power, actions taken
after the accident make it unlikely that an event like this will occur
again.
DISCUSSION
The
public’s opinion regarding nuclear power has changed markedly over the
years. When the first nuclear plants
began operating in the 1950’s, the public’s response was overwhelmingly positive. A survey conducted in 1956, for example,
“showed that 69% of those questioned had ‘no fear’ of having a nuclear plant
located in their community, while only 20% expressed concern” (Walker,
2004). In the 1960’s, when the nuclear
industry began to grow quickly, the public remained supportive of this source
of power. Specifically, in 1960, 64% of
the public felt “atomic power should be used to produce electricity” (Walker,
2004). The public’s increasing concern
for the environment likely helps explain these positive impressions. Fossil-fuel burning plants were, at the time,
providing over 85% of the United States’ electricity, and the emissions of
these plants included large amounts of sulfur dioxide, nitrogen oxides, carbon
dioxide and mercury, to name a few.
Nuclear power plants, on the other hand, did not emit any of these
pollutants, so the public looked towards this relatively new source of power as
a clean alternative to fossil fuel combustion.
Although the public had clearly become more concerned with the
environment, its demand for electricity was still growing fast. Nuclear power, however, could provide this
energy. The enthusiasm towards nuclear
power continued into the early 1970’s.
Figure 1 helps show just how enthusiastic both the public and electric
utilities were towards nuclear power during the 1950’s through the early
1970’s.
Figure
1. Purchases of nuclear reactors, 1955-1978.
Source:
Derived from Walker (2004).
Between 1955 and 1965, utilities
purchased a total of twenty-two reactors, and in 1973 alone, a total of
forty-four reactors were bought. It was
predicted that by 2000 that over 1,000 nuclear plants would be producing energy
in the United States
(Walker, 2004). Yet, just a few years later, purchases of
nuclear reactors plunged. A number of
factors can explain this somewhat surprising occurrence.
The
first of these factors is the economic recession that began in 1973. In 1973, the Organization of Oil Exporting
Countries (OPEC) imposed an oil embargo on the United
States because of the former’s support of Israel
during the Yom Kippur War. Because the United
States was importing a significant
percentage of its oil, this event had disastrous economic consequences: the
skyrocketing oil prices ultimately led to negative GDP growth rates, inflation
(which was already high), lower wages, and high unemployment. As a result of the recession, it became
difficult for electric utilities to finance their purchases of nuclear plants,
and the construction of many plants was delayed or even cancelled, doing
nothing to lessen the United States’ dependence on foreign oil (Walker,
2004). Eventually, the recession would
come to an end. One might tend to think
that orders for nuclear plants would increase after their finance once again
became possible. After all, the economic
recession had just shown the country the dangers of being overly dependent on
foreign oil. Around this same period of
time, however, Americans were becoming more aware of – and concerned with --
the risks associated with nuclear power.
It was a known fact at the time that exposure to high levels of
radiation could be deadly, but there was still debate over the health effects
of the low levels of radiation that are released as nuclear plants routinely
operate. Individuals concerned with the
environment and public health also worried about the radioactive waste produced
by nuclear plants. In addition, many
worried about the possibility of meltdown that could result, for example, from
the failure of the core’s cooling system. For many Americans, these risks outweighed
the benefits of nuclear power, discussed earlier (Walker,
2004).
When
the Nuclear Regulatory Commission issued an operating license in February 1978
to unit two of the Three Mile Island (TMI-2) nuclear generation station, then, many Americans
were aware of the risks associated with this type of power. Those living in the small towns nearby this
plant, however, seemed to have few objections regarding the plant; in fact,
many welcomed the hundreds of new jobs which the plant would create (Walker,
2004). Plus, the plant’s safety systems
should make the probability of any accident very small. If, for example, the coolant that normally
prevents the core from overheating were prevented from doing so, then the
plant’s emergency core cooling system (ECCS) could just flood the core with
water, effectively cooling it and making a core meltdown almost
impossible. Even if this meltdown did
occur, the release of radiation would be small due to the core’s containment
and other safety features. Although the
ECCS concept looked good on paper, the Atomic Energy Commission (AEC) initially
had little evidence “to show that ECCS would perform as designed” (Walker,
2004). In the early 1970’s, experiments
with ECCS did not yield promising results.
These early experiments seemed to suggest that coolant water from ECCS
could potentially be blocked from reaching the core if the pressure, due to the
core’s starting to overheat, became too high.
After more research and testing of ECCS, the NRC eventually would state
that ECCS would work as designed, preventing the core from melting down in the
event of a loss of coolant accident.
Before
commercial operation, the TMI-2 had been
thoroughly tested. During the test
phase, the plant exhibited numerous problems, including problems with its
coolant pumps, some valves, feedwater pumps, and its ECCS. Although this might sound alarming, it is not
unusual for plants to run into problems during their testing periods. In December 1978, the plant began producing
power commercially. Just three months
later, on March 28, 1979 at
4 AM, the plant would experience the
malfunction that would ultimately lead to the nuclear accident at Three
Mile Island with which almost everyone is familiar. At this time, the pumps in the secondary
loop, shown in Figure 2, shut down unexpectedly. The function of the secondary loop, also shown
in Figure 2, is to receive heat
Figure 2. A nuclear reactor, like the
one at TMI-2.
Source: http://www.pbs.org/wgbh/amex/three/sfeature/tmihow.html
from the very hot water in the
primary loop, which is hot since it absorbs heat from the core. When the pumps in the secondary loop shut
down, this heat transfer from the primary loop to the secondary loop was unable
to occur, and as a result, heat and pressure in the primary loop increased. Seconds later, the pilot-operated relief
valve (PORV) opened as designed, so as to relieve some of the building pressure
and heat. Around this same time, backup
pumps had turned on automatically to compensate for the pump within the
secondary loop that had shut down earlier.
Somehow, though, two valves had been left closed (they should have been
open), so the backup pump was unable to perform as designed. Workers in the control room, however, had no
way of being aware of this fact; they thought both loops were working as
designed (http://www.pbs.org/wgbh/amex/three/sfeature/tmiwhattxt.html).
After
being open for a few seconds, the PORV had performed its job, relieving heat
and pressure to normal levels. In the
control room, computers indicated the PORV had, as designed, closed after doing
its job. In reality, however, the valve
remained open. Coolant that should have
reached the reactor instead flowed out the valve, creating a loss of coolant
accident which plant operators were unaware of.
Since the core was now not getting enough coolant, the emergency core
cooling system, or ECCS (shown in Figure 2 as EIW, emergency injection water)
released coolant to absorb the core’s heat, as designed. After being on for a few minutes, workers
turned off ECCS, as it appeared water levels were starting to get too high. In reality, though, water levels in the
primary loop were too low. The PORV was
still open at this time, and water continued to escape out of this valve. As water flow to the core was now even more
insufficient, temperatures increased and water was converted to steam. As this steam moved through the primary loop,
the primary pumps began to vibrate violently.
Workers, still not aware they were dealing with a loss of coolant
accident, decided to turn off some of these pump, further decreasing water flow
to the core. As a result, the core
temperature increased even more, and more water was converted to steam. Ultimately, water levels dropped so low that
the top of the core was exposed. The
fuel rods, now exposed to the steam, reacted chemically with the steam,
releasing hydrogen and radioactive gases
(http://www.pbs.org/wgbh/amex/three/sfeature/tmiwhattxt.html).
Finally,
almost three hours into the accident, a worker realized the PORV was still open. The valve was closed. It was later determined that over one-third
of the cooling water in the primary loop had escaped through this valve in the
time it was open (Walker,
2004). No one on duty at the time,
however, thought to check how much water had been lost, so the core just kept
getting hotter and hotter, releasing more hydrogen and radiation. Radiation alarms went off eventually, prompting
workers to declare an emergency. Though
the radioactivity of the water in the primary loop was extremely high,
radiation levels outside the plant were either normal or, closer to the plant,
just slightly above normal. Around this
same time, workers noticed that temperatures were extremely high within the
core, a sign of a possible loss of coolant accident. Ultimately, after half of the core was
uncovered, water was pumped back into the primary loop. Later, the primary pumps were turned back on,
releasing water into the core. Nearly 16
hours after the accident began, the core temperature was lowered to safe
levels, and a complete meltdown of the core was avoided (http://www.pbs.org/wgbh/amex/three/sfeature/tmiwhattxt.html).
There
were some questions after the situation at TMI-2 was brought under control
regarding how much radiation may have leaked from the plant. A number of organizations, including the NRC,
the Environmental Protection Agency, the Department of Health, and the state of
Pennsylvania, in addition to a
number of independent studies, conducted studies to answer this question. All studies indicated that the average dose
of radiation received by the two million people surrounding the plant was only
one millirem. Relative to the 100-125
millirem this area received naturally each year, then, this dose appears
small. Later studies would go on to show
that most of the radiation was contained by the plant’s containment building (http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html). At the time that the general emergency was
declared at the plant, radiation levels in this part of the plant were probably
800 rads per hour or more. This figure
would eventually rise to as high as 6,000 rads per hour. To put these figures into perspective, most
scientists feel human exposure to 50 rads or more for a short period of time
would likely cause serious health effects; doses over 600 to 1000 rads would
likely be deadly (Walker, 2004).
The
NRC has taken numerous steps to prevent an accident like the one that occurred
at Three Mile Island from ever happening again. They state that, "the problems
identified from careful analysis of the events [of TMI-2] have led to permanent
and sweeping changes in how NRC regulates its licensees -- which, in turn, has
reduced the risk to public health and safety” (http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html). Since the accident resulted due to human
error as well as design deficiencies, and component failures, according to the
NRC, these changes really were varied.
The NRC website lists some of these changes. They include upgrading and strengthening of
plant design and equipment requirements, revamping operator training and
staffing requirements, improved instrumentation and controls for operating the
plant, and enhancement of emergency preparedness to name a few. A complete list of these changes as well as
others can be found at the NRC website (http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html).
CONCLUSION
Public
opinion towards nuclear power varied between the 1950’s and 1970’s. While the public was initially receptive
towards this source of power as a means of providing clean energy, public
opinion would soon change, especially in the 1970’s, as its potential hazards
were revealed. The events that occurred
at Three Mile Island as a result of human error and
equipment failure in the spring of 1979 only served to confirm critics’ worst
fears. Thankfully, the containment
building was able to contain the large amount of radiation released due to this
loss of coolant accident.
Despite
the potential for nuclear accidents, as the incident at Three Mile
Island illustrates, we should be reminded that the risk of such an
occurrence is extremely low.
Specifically, risk assessment suggests only a 1 in 40,000 chance per
year of damage to a nuclear reactor, with the probability of actual releases of
radiation even lower. Moreover, risk
assessment indicates that the risk of death due to radiation for those living
near plants is less than 1 in 1 million (www.nei.org). Finally, action taken by the NRC after the
TMI-2 incident has likely played a role in decreased risks as well.
Although
the public surely will never forget the events that occurred at Three
Mile Island over 25 years ago, recent polls show increasing
acceptance of nuclear power. In late
2002, Bisconti Research, Inc. conducted a poll of 1000 adults and 481 college
graduates. The poll shows that 73% of
college graduate voters and 65% of all adults favor the use of nuclear power in
the United States. Interestingly, the poll indicates that
support of nuclear energy is highest in the 35-49 years old and 50+ years old
age categories – categories that include individuals who are sufficiently old
enough to have lived through and remember the events at Three Mile
Island. Furthermore, 59% of
college graduates and 55% of all adults feel that more nuclear power plants
should be built in the United States
(http://www.nei.org/documents/PublicOpinion_02-12.pdf). Back in the 1960’s, an article in Nucleonics
Week stated “if the public does not accept nuclear power, there will be no
nuclear power” (Walker, 2004). Does this increasing acceptance, then,
suggest a greater role for nuclear power in the future? Both risk assessment and the NRC seem to suggest
nuclear power is safer now than ever. Moreover,
as the United States’
demand for energy, dependence on foreign fossil fuel imports grows, and
(hopefully) concern for the environment grows, the appeal for nuclear power
will likely grow as well.
BIBLIOGRAPHY
Nuclear Energy Institute, 2004, Perspective on Public
Opinion, http://www.nei.org/documents/PublicOpinion_02-12.pdf
Nuclear Regulatory Commission, 2004, Fact Sheet on the
Accident at Three Mile Island, http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html
PBS, 2004, What Happened: Step by Step, http://www.pbs.org/wgbh/amex/three/sfeature/tmiwhattxt.html
Walker, Samuel J., 2004, A Nuclear Crisis in Perspective: Three
Mile Island:
Berkeley
and Los Angeles, CA,
University of California
Press.