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Three Mile Island revisited
Ann. nucL Eneryy, Vol. 17, No. 7, pp. 393-398, 1990 Printed in Great Britain
0306-4549/90 $3.00+0.00 Pergamon Press pie
LETTER TO THE EDITORSt T H R E E MILE ISLAND REVISITED (Received 11 January 1990)
The subject of the Three Mile Island accident holds my personal interest both as a scientist and as a native of York, Pennsylvania, a neighboring town to the reactor site. As a boy I swam and fished in the Susquehanna river, in which Three Mile Island is located, and as a staff member for the U.S. Nuclear Regulatory Commission (NRC), I became involved with severe accident policy issues in the aftermath of the TMI accident. I especially remember an official inspection tour of the TM1 site in 1973 while employed by the Atomic Energy Commission. At that time, no one I talked with on either side of the river was notably frightened or concerned about the prospect of a nuclear accident. One of my most vivid impressions was the fortress-like construction of the reactor containment building of the unfinished Unit-2, a silent testimony to one important feature of the defense-indepth philosophy in the design, construction and operation of nuclear power plants in America. Then came the major accident of 28 March, 1979 to this TMI unit, the worst accident in the history of nuclear power generation until Chernobyl. Although I understood the seriousness of the event, my assignment then at the NRC gave me no immediate responsibilities in connection with the ~Lccident. But from 1983 to 1985, as Special Assistant for Policy Development in the Office of Nuclear Reactor Regulation, I was involved in drafting, coordinating and editing inputs in the development of the NRC's Severe Accident Policy Statement (NRC, 1980, 1985a, b). This statement and its supporting rationale constituted a response to safety and regulatory issues identified in the Report o f the President's Commission on the Accident at Three Mile lsland (The Kemeny Report) (Kemeny et al., 1979) and the investigation commissioned by the NRC itself, Three Mile Island: A Report to the Commissioners and to the Public (the Rogovin Report) (Rogovin et al., 1980). It is with this background that I present the following discussion of the TMI accident, its causes, its major effects and what else we may yet learn from it.
BRIEF SCENARIO OF THE TMI ACCIDENT
The main accident precursor event was the clogging of the condensate demineralizing system and the inadvertent shutdown during maintenance to remove the clogging. This shutdown interrupted the flow of feedwater to the steam generator. This event is believed to be a partial "failure"
t An invited essay in a forthcoming anthology, The Continuiny Debate : Ethics and Nuclear Eneryy (F. S. Carney and A. Sherman, Eds). The Ethics and Public Policy Center, Washington, D.C.
of engineering design involving equipment not formally designated as "safety-related." The next potentially significant event was the failure of the safety-related emergency feedwater system that came on automatically as per design. However, two important valves were closed (because of human error), which prevented water essential to the functioning of the steam generator to reach its target until the problem was discovered 8 min later. Because of the operator recovery action in opening these valves, this mistake was unimportant to the eventual course of the accident, except possibly for its distracting effect on the operators, contributing to their inability to diagnose the true status of the accident in progress. The most vital equipment failure in terms of ultimate consequences came when the electromatic pilot-operated relief valve (PORV) did not close after properly opening to relieve pressure build-up in the primary coolant (water) system servicing the reactor core. Because of a lack of reliable indicators (a design failure) and a lack of understanding (a human failure), the fact that the PORV had not closed remained undetected and uncorrected for 2 h and 20 min. However, the damage from these equipment and human breakdowns extended long after corrective action was taken. The problem was that the operators did not recognize how much coolant water had been lost from the reactor core during the period the PORV was stuck in the open position. But even these events would not have been so grave were it not for the disastrous operator decision about 3 min into the accident to bypass the high-pressure injection emergency core cooling system (ECCS). As designed, the ECCS came on automatically with a drop in coolant pressure. Ironically, the operator action resulted from the mistaken belief that the ECCS bypass was needed to prevent a "loss of coolant accident" (LOCA) from happening. In truth, the stuck-open PORV already constituted a LOCA that eventually led to a steam void in the top of the reactor that ultimately uncovered part of the reactor core and led to fuel melt. When the operators succeeded in starting the reactor coolant pump about 13' h into the accident, the most critical part of the accident was essentially over. However, this fact was not recognized until several days later because of serious differences of opinion over the possible hazard posed by the hydrogen generated by overheating of the fuel rods. The hydrogen bubble scare led to a major evacuation on Friday 30 March, the third day of the accident. The utility had released radioactive gas early that morning in a manner indicating that utility personnel might not be in complete control. The release had prompted Pennsylvania Governor Richard Thornburgh to recommend that invididuals living within 10 miles of the plant stay indoors and that pregnant women and young children within 5 miles of the plant leave the area. This was followed by a press briefing by two NRC staff
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members. In responding to the question "Is a meltdown possible?" one staff member replies, "Yes, there is a possibility . . . . I think everyone technical would have to concede that if the reactor was depressurized, and the hydrogen bubble expanded, there is a possibility, not a likelihood, but a possibility that things could go wrong, or all the cooling systems quit." The regulator's dilemma in deciding on a response to "what-if" questions regarding possible scenarios of an accident in progress is extraordinarily difficult and personally hazardous. A candid reply, such as the one just stated, avoids the distrust that often results from concealment of information. But it also may drastically elevate the risk of creating profound psychological stress among the public in an exaggerated way that may be inimical to the public's own interests. Thus, there is cause to ponder whether paternalism (or elitism) in certain situations should be viewed with the suspicion or disdain it is sometimes accorded (Spangler, 1985). There was scientific debate during the TMI accident over the possibility that the hydrogen bubble might combine with oxygen and explode. At 3:41 p.m. on Friday afternoon, NRC Chairman Joseph I-Iendrie responded to Governor Thornburgh's query on the hydrogen bubble's explosive potential. His reassuring reply was, "There isn't any oxygen in there to combine with that hydrogen, so the answer, as far as I know, is pretty close to zero" (Rogovin et al., 1980). Yet it was not until after intense consultation with experts during the next 2 days that Hendrie and NRC Director Harold Denton were able to confirm the correctness of this view to the Governor at 8:45 p.m. on Sunday. The role of the media in relating the events on Friday is epitomized by the opening remarks by Walter Cronkite in his CBS evening (TV) news program : "The world has never known a day quite like today. It faced considerable uncertainties and dangers of the worst nuclear power plant accident of the atomic age. And the horror tonight is that it could get much worse. It is not an atomic explosion that is feared; the experts say that is impossible. But the specter was raised (of) perhaps the next most serious kind of nuclear catastrophe, a massive release of radioactivity. The Nuclear Reactor Regulatory Commission cited that possibility with an announcement that, while it is not likely, the potential is there for the ultimate risk of a meltdown at the Three Mile Island Atomic Plant outside Harrisburg, Pennsylvania" (Cronkite et al., 1979). Cronkite's remarks are regarded by many as an example of sensational journalism, focusing on such words as "horror," "specter" and "catastrophe." David Rubin, a member of the Public's Right to Know Task Force of the President's Commission on the Accident at TMI, defended Cronkite's introduction as an accurate summary of what was then known about the course of the accident : "The 'horror' of the situation getting much worse did not materialize, but Cronkite can hardly be blamed for that. He was only reporting concerns voiced by members of the nuclear establishment" (Rubin, 1981). Rubin noted that, by any measure, 30 March was a disturbing and confusing day for those living near the plant. One of the lessons learned from this experience was the need to expand our scientific understanding about nuclear accident progression phenomena, including the survivability of safety equipment under environmental conditions of a severe nuclear accident. This knowledge could improve equipment design and accident management capabilities that
would halt or limit the consequences of a severe accident. NRC's Severe Accident Research Plan of 1983 placed considerable emphasis on these needs (NRC, 1983a) and has produced useful results. CONSEQUENCES OF THE ACCIDENT What were the major health, economic and socio-political consequences of the accident? Regarding health consequences, the President's Commission (the Kemeny Report) concluded that the amount of radiation received by any one individual outside the plant was very low (Kemeny et al., 1979). It estimated that less than one (delayed) cancer fatality is likely to be induced by the accidental release of radionuclides at TMI. This effect would be undetectable among the 325,000 people projected to die of cancer from routine causes having nothing to do with the power plant in the population of over 2 million persons living within 50 miles of TMI. Genetic defects from the radiation are estimated to be similarly small and undetectable. Indeed, the extended life span study of the A-bomb survivors at Nagasaki and Hiroshima, who received far higher levels of radiation than the exposed individuals near TMI, reveals that it took a period of from 30 to 33 yr after the bomb explosion over Nagasaki before a statistically significant excess of cancer deaths occurred there (Kato and Schull, 1982). Moreover, studies of numerous health indicators for 105,000 children born between 1946 and 1980 to parents exposed to A-bomb radiation in these cities fail to confirm any harmful genetic effects (Committee for the Compilation of Materials on Damage Caused by the Atomic Bombs in Hiroshima and Nagasaki, 1981). An increase of 5-10% would have been expected based on theoretical methods of dose-effect estimation. The Kemeny Report also concluded that the most serious health effect of the TMI accident was severe mental stress, which was generally short-lived. The highest levels of stress were found among those living within 5 miles of TMI and in families with preschool children. One of the most unexpected results of the psychological research following the accident was that reactions tended to be extreme: some people were virtually oblivious to the potential gravity of the situation whereas others were traumatized by it (Flynn, 1982). Psychological stress also recurred in response to later events, namely the necessary venting of radioactive krypton gas following the accident, the proposed discharge of cleanup liquids into the Susquehanna River at such low radiation doses as to remain below the limits of EPA protection standards, and the regulatory action that permitted restart of the undamaged Unit 1 that was down for maintenance at the time of the TMI-2 accident. Although the NRC conducted a public workshop with invited experts to explore these matters (Walker et al., 1982) and the Department of Energy contracted for a study report on the social and psychological impacts of Unit I restart (Sorenson et al., 1983), the Supreme Court ultimately ruled that the NRC was not required to deal with the psychological stress issue in the restart of Unit 1 (Metropolitan Edison v. Pane, 1983). As to economic consequences of the TMI accident, a survey of the effect of the accident on property values based on sales in the vicinity of TMI showed very limited impact (Gamble and Downing, 1981). But the property damages and make-up (purchased) energy costs incurred by the utility (GPU) resulting from the accident have been quite severe. The GPU estimated the clean-up costs of Unit 2 at $965 million, of which $731 million has already been spent. Unit
Letter to the Editors 1 was not permitted by the NRC to operate for the period between March 1979 and October 1985 with estimated makeup energy penalties of $12-15 million per month. A similar rate of make-up energy penalty for the somewhat larger Unit 2 is still being incurred. Thus, the make-up energy penalties for both units from April 1979 to June 1987 total $2.6 billion (borne by the utility's customers) with more yet to come for Unit 2 outage. Other nuclear utilities also incurred millions of dollars of backfit costs following the TMI accident. However, an even greater impact is the accident's adverse effect on the prospects for new plant orders, plus large financial losses from the cancellation of dozens of plants in a partially constructed state (Spangler, 1986). As to socio-political consequences, it has been pointed out that the TMI accident stimulated an immediate rise in antinuclear fervor, especially among the sizable and tenacious opposition movement that existed prior to the accident (Slovic et al., 1982). The potential health risks incurred under nuclear systems were viewed as substantially greater than the health effects of alternative energy sources. This was a result of the involuntary and catastrophic nature of nuclear risks, as well as its attributes of newness and dread (Fischhoff et aL, 1978).
RESPONSIBILITY FOR THE ACCIDENT Both the Kemeny Report (Kemeny et al., 1979) and the Rogovin Report (Rogovin et al., 1980), among others, search for root causes of the accident and the identification of measures which, if they had been implemented on a timely and effective basis, might have prevented or limited the accident. These measures were so numerous and so institutionally diverse that, in truth, no one party (the NRC, the operating utility management, the plant operators, the reactor or plant vendors, and certain equipment manufacturers) could escape discredit for their failures. Certainly, blame for the reactor operators' errors is substantially mitigated by a number of factors for which others were responsible: (1) the inadequacy of operator training to diagnose and effectively manage a severe accident so as to limit its consequences, including an understanding of the severe accident risk importance of accident percursor events ; (2) the inadequacies of instrumentation to denote the open/closed position of key valves or the insufficiency of coolant water in the reactor vessel, etc. ; and (3) the inadequacy of control room design to improve operator effectiveness in handling emergencies, including computer-aided diagnostic capability (Jaffe, 1981). The Kemeny Report also laid stress on the nature of "mindsets" as a contributory cause of the TMI-2 accident (Kemeny et aL, 1979). After many years of operation of nuclear power plants, with no evidence that any member of the general public has been hurt, the belief that nuclear power plants are sufficiently safe grew into a conviction. One must recognize this to understand why many key steps that could have prevented the accident at Three Mile Island were not taken. The Commission is convinced that this attitude must be changed to one that says nuclear power is by its very nature potentially dangerous, and, therefore, one must continually question whether the safeguards already in place are sufficient to prevent major accidents. A comprehensive system is required in which equipment and human beings are treated with equal importance.
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The Rogovin Report took these criticisms by the Kemeny Report to heart along with the insights from its own investigation of the accident. The scope of its conclusions and recommendations included the following concerns: (I) systematic evaluation of operating experience and improvement in the regulation of operating reactors ; (2) strengthening the onsite technical and management capability of the utility: improved operator training and new NRC requirements for qualified engineer supervisors on every shift; (3) greater application of human factors engineering, including better instrumentation display and improved control room design ; (4) more remote siting and improved emergency planning, including workable evacuation planning as a condition of reactor operation ; (5) overhaul of the licensing process : onestage licensing, increased standardization, increased use of rulemaking; and (6) improvement in the bases for safety review of reactor design and increased use of quantitative risk assessment techniques (Rogovin et al., 1980). These and other reports (NRC, 1980a, b) led to a massive effort imposed on utilities to backfit certain equipment changes and to implement numerous procedures involving maintenance and operation of their nuclear power plants. As noted in a recent One Time Report to Congress, the 151 utility implementation tasks identified by NRC and the three other items have resulted in a total of 6531 implementation actions (NRC, 1987). Of these, 5900, or about 90%, have been completed at the 65 plants operating at the time of the TMI accident. By the end of the calendar year 1989, all but 16 tasks will be implemented at all 65 reactors. This will equate to about 6200 implementation actions completed by the licensees or about 95% of the total requirements at these plants. Having been charged with under-regulating on behalf of safety, the NRC staffzealously pursued the above exhaustive list of tasks. This soon raised questions about the possibility of over-regulating on behalf of safety (NRC, 1981). The promotion of nuclear power, of course, is not a function of the Nuclear Regulatory Commission. Indeed, the Energy Reorganization Act of 1974, which established the NRC, made it quite clear that the agency's primary responsibility is the regulation of commercial nuclear power so as to assure adequate protection of public safey and health. Nevertheless, it seems reasonable that Congress did not intend regulatory policies, practices and decisions to be made in a manner that would be "anti" nuclear power, such as by employing regulatory practices that would yield small marginal gains in safety benefits in return for unreasonable costs, or would cause unconscionable or unwarranted delays or regulatory uncertainties that would deter utilities and the financial community from seriously considering the nuclear option (Denton, 1983). One of the important tools to achieve an appropriate balance between under- and over-regulation is the establishment of safety goals and, in particular, a safety-cost trade-off criterion. The Kemeny Report (Kemeny et al., 1979) recommended that "Included in the (NRC's) general substantive charge should be the requirement to establish and explain safety-cost trade-offs; where additional safety improvements are not clearly outweighed by cost considerations, there should be a presumption in favor of the safety change." It has also been recognized (Denton, 1986) that more careful attention should be given to the rationalization of the separate and cooperative roles of government and industry that would provide an optimal combination of safety and economy for the future of nuclear power in serving the national interests.
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Letter to the Editors
LESSONS
TO BE LEARNED
FROM MISTAKES
MADE
In the early days of commercial nuclear power, enthusiasts clearly expected, with some justification, that this technology would become the wave of the future. According to 1974 forecasts of the U.S. Atomic Energy Commission (AEC, 1974). 1000 such olants would be oueratine in the U.S. bv the turn of the century. It was believed That this “technological goose” was destined to lay an abundance of golden eggs for the benefit of humankind, or so the enthusiasts firmly believed. Then a tidal change occurred. Although the 109 licensed nuclear plants in the U.S. today operate with comparatively low fuel costs, there have been no new nuclear power plants ordered since 1978. As of 1 January 1987, a total of 114 plants previously ordered have been cancelled. Many feel that the nuclear industry’s goose has been cooked before it had a chance to lay the promised golden eggs. They point to the public fear created by the accidents at TM1 and Chernobyl and the rising capital costs of nuclear plants because of regulatory delays and the expense of technology fixes on behalf of safety improvements following TMI. Yet I believe a different scenario for future nuclear power developments in the U.S. is still possible, however improbable it may seem today. Ironically, if the nuclear industry and its regulators had set out in the period before the midEast oil embargo in October 1973 to design a “developmental” scenario to sabotage the chances for success of nuclear technology in America, it could well have done so by fostering the very mistakes in strategic planning and prescience that have actually transpired. Ten important mistakes that contributed to the TM1 accident and the public’s perception of the desirability of nuclear energy were : 1. LA many flowers bloom--In the U.S. laissez faire system of government it was not practical to legislate (nor to mandate through regulation) a standard plant design approach even if its importance had been properly understood in this early period. Although private industry normally pursues strategic planning functions, nothing emerged from industry during those days to call attention to, or to effectively thwart, the disastrous effects on safety practices, the regulatory inefficiences, and the diseconomies in plant construction that would arise from the uncontrolled proliferation of custom designs of nuclear power plants. 2. Vesting the primary responsibility for safety in a regulatory agency-However appealing this approach may sound in theory, in practice it is self-defeating. This is not to say that a regulatory agency does not have an important, and even vital, role for assuring safety. But the tendency of regulatory agencies to establish minimum acceptable standards of technological and managerial performance on behalf of safety serves to inhibit the very pursuit of excellence by those responsible for the design, construction, operation and maintenace of nuclear plants, unless these parties understand that theirs is the primary responsibility for achieving safety. 3. The initial weak role of utilities-The
corollary to the above mistake is that many utilities, in the early stages of the nuclear industry, were only too willing to play a subordinate role in supervising the design and construction of nuclear power plants and in strategizing safety practices for their operation and maintenance. It may have been slick sales practices for vendors to tell potential utility customers that a nuclear reactor is “just another way of boiling water” at a time when
they held this high technology in awe. But the utilities’ willingness to be spoon-fed safety procedures and practices was unwise in the extreme. 4. Excessive
adversariahsm
in the regulatory decision
process-A certain amount of adversary or debate can be quite productive in serving or protecting societal values and interests. However, the adversarial relations that often developed between regulators (the AEC and subsequently the NRC) and the regulated industry (utilities and vendors), as well as with individuals and public interest groups who were intervenors at licensing and safety hearings, were often excessive, poorly-controlled and hence counterproductive to the interests of society. 5. Inadequate severe accident safety research-Although considerable safety research was mounted by the government (and supplemented by industry), many features of NRC’s Severe Accident Research Plan of 1983 (NRC, 1983) should have been established at a much earlier stage of the industry’s development. 6. Insujicient attention to technology transfer-In the development of complex technologies, the effectiveness of transferring “hands-on” learning experiences from the mistakes and best practices of those who implement technologies is essential to accelerate leaming curves that achieve industry-wide improvements in the cost, safety and the ultimate benefits to society of a given technology. The nuclear industry was slow to transfer the technological lessons of systems reliability engineering, human factors engineering, and control room design from the more advanced aerospace and defense industry. Perhaps even worse, the proliferation of custom plant designs (the failure to standardize) worked strongly against the transfer of “learning curve” experience from one unit of the industry to others, a practice now recognized to be in their mutual interest. 7. The failure of forecasts-While we cannot expect perfection in the hazardous art of forecasting, the excessive projections of electrical energy demand, and the rapid escalation of all fuel prices following the mid-East oil embargo (which fostered energy conservation), exacted severe penalties (as much as 100%) on nuclear power plant construction costs. Excessive generating capacity and reserve margins of utilities, because of overforecasting of demand, yielded both multi-year stretchouts in construction for both coal and nuclear plants and cancellation of new units. Had correct forecasts been made, this would have produced a reduced rate of plant orders. It would also have led to a much less chaotic stress on limited industry and regulatory resources, with more attention to the training of the new requisite skills that were in short supply. 8. The failure to solve waste management problems on a timely basis-Provisions for the permanent storage of
high-level wastes were seen as postponable in the early days when many plants were first being constructed and spent fuel reprocessing was envisioned as part of the “game plan.” 9. The failure to educate the public on the comparative safety and benefits of nuclear energy-The responsi-
bility for performing this function was quite diffused and unorganized. I suspect the main reason NRC does not today play a more vigorous role in this function is the desire to avoid an image of promotionalism. Yet the requirement of the National Enviornmental Policy
Letter to the Editors Act in making risk-cost-benefit analysis of alternatives does generate useful information related to this need. Shortcomings in public understanding of such issues can be viewed only as a major impediment to the solution of the nuclear industry's problems. 10. The failure to anticipate the public and political opposition to nucelar energy arising from all o f the above failures. IS THE TMI BONE OUT OF THE NATION'S THROAT?. As previously noted, most of the needed safety changes for both new and on-line reactors have now been determined and completed. Moreover, many of the industry and regulatory philosophies or approaches that led to failure have either been resolved or are well on their way to resolution. Thus, it is fair to ask, "Is the TMI accident bone now out of the nation's throat?" Not completely, I believe. There are two requirements that still must be met. First, it is necessary to demonstrate to the public and to investors that nuclear power plants can be operated more safely. This must include a notable reduction in the frequency of the more significant accident precursor events at nuclear plants, events that cause defense-in-depth engineered safety features to operate and that become newsworthy events in the local and national media. It is true, programs and industry organizations have emerged to deal more effectively with severe accident issues.t The second requirement to get the TMI bone out of the nation's throat is that it must be demonstated quite convincingly that a new nuclear power plant, when ordered, can be constructed on a controlled schedule and at a cost that restores the significant economic advantage relative to alternative sources of energy that nuclear power once had in the U.S. (and still has in several nations in the world employing reactors of basic U.S. technological design). One of the "wrong lessons" from TMI that many of the public and some investors perceive is that the cost escalation of nuclear power plants following TMI is necessarily a permanent part of the cost structure of nuclear power. The centerpiece of any effective strategy to meet these requirements is the successful adoption of the standardization approach to nuclear plant design. It will be necessary that industry pursue a standardized rather than a custom design approach. The utilities now appear to have universally accepted the view that standardization is the only approach capable of demonstrating that future U.S. nuclear plants can be built and operated with acceptable safety and economy. It is important to note two countries firmly committed to the nuclear option, namely France and Japan, have successfully demonstrated that the standardization approach can achieve the twin goals of acceptable safety and economy. France, which now generates 70% of its electricity from nuclear fuel, routinely builds standard nuclear plants of basic U.S. design within 6 yr. And Japan, the only country to have experienced the immediate and delayed adverse health effects of radiation from the A-bombs, has overcome its public fears of nuclear energy through a now-famed "pursuit-oft These include the Institute for Nuclear Power Operations (INPO), the Nuclear Safety Analysis Center (a part of the Electric Research Power Institute) and the Industry Degraded Core Rulemaking (IDCOR) Program under the sponsorship of nuclear utilities and coordinated by the Atomic Industrial Forum.
397
excellence" philosophy in achieving demonstrable nuclear safety by limiting accident precursor failures. Quite encouragingiy, the U.S. is now actively pursuing two quite contrasting approaches in developing safer and more economical new standard plant designs. The first of these is the Advanced Light Water Reactor design (ALWR) being developed by the Electric Power Research Institute (Taylor, 1985). The safety improvements sought for the mid1990s would be evolutionary changes based on the best available features of proven technology of current pressurized water reactor (PWR) and boiling water reactor (BWR) designs. The second approach, being sponsored by the U.S. Department of Energy in conjunction with private contractors, is the development of three advanced reactor designs: a Modular High Temperature Gas-cooled Reactor (MHTGR), a Sodium Advanced Fast Reactor (SAFR) and a liquid metal reactor (Power Reactor Inherently Safe Module called PRISM). More radical in concept, this approach combines certain inherently safe design features with potential market advantages of small modular units. The modules could hopefully be more economically manufactured at central factories than the large-scale LWRs requiring a higher proportion of their construction to occur onsite where less predictable and less controllable factors of project management may contribute to cost overruns. Belatedly, the U.S. has recognized the folly of its early love affair with custom plant designs. Perhaps it will yet be possible to test what success the U.S. can achieve in harnessing the atom both safely and economically for commercial electricity production by adopting a standardization approach and other appropriate strategies. The potential benefits of such strategies became clearer through the agonizing introspection caused by the TMI accident and its follow-up programs. It is a sad fact of history that the most important lessons are often learned after the tragedies of preventable accidents. It is left to history to answer whether the TMI injury will yet aid the nuclear "goose" to lay some of the golden eggs that were prematurely expected of it. Techno-Planning, Inc. 9115 McDonald Drive, Bethesda MD 20817, U.S.A.
MILLER B. SPANGLER
REFERENCES
AEC (1974) Report WASH-I174-74, U.S. Atomic Energy Commission. Committee for the Compilation of Materials on Damage Caused by the Atomic Bombs in Hiroshima and Nagasaki (1981) Hiroshima and Nagasaki: The Physical, Medical and Social Effects of the Atomic Bombing. Basic Books, New York. Cronkite W. et al. (1979) CBS Evening News with Walter Cronkite, 30 March. Columbia Broadcasting System, New York. Denton H. R. (1983) The Energy J. 4, 125-141. Denton H. R. (1986) Nucl. Engng Des. 92, 303-322. Fischhoff B. and Slovic P. et al. (1978) Policy Sci. 9, 127-152. Flynn C. B. (1982) Accident at Three Mile Island: The Human Dimensions (D. L. Sills, C. P. Wolf and V. B. Shelanski, Eds), pp. 49-63. Westview Press, Boulder. See also Report NUREG/CR-2749, U.S. Nuclear Regulatory Commission. Gamble H. B. and Downing R. H. (1981) Report NUREG/ CR-2063, U.S. Nuclear Regulatory Commission. Jaffe L. (1981) The Three Mile Island Nuclear Accident:
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Lessons andlmplications (T. H. Moss and D. L. Sills, Eds), Annals of the New York Academy of Sciences, Vol. 365,
pp. 37-47. Kato H. and Schull W. J. (1982) Radiat. Res. 90, 395-432. Kemeny J. et al. (1979) Report on the President "sCommission on the Accident at Three Mile Island: The Need for Change. U.S. Govt Printing Office, Washington, D.C.
Metropolitan Edison v. Pane (1983) Report 460 USC 766. NRC (1980a) Report NUREG-0660, U.S. Nuclear Regulatory Commission. NRC (1980b) Report NUREG-0737, U.S. Nuclear Regulatory Commission. NRC (1981) Report NUREG-0839, U.S. Nuclear Regulatory Commission. NRC (1983) Report NUREG-0900, U.S. Nuclear Regulatory Commission. NRC (1985a) Federal Register 50(153), 32138-32151. NRC (1985b) Report NUREG-1070, U.S. Nuclear Regulatory Commission. NRC (1987) One Time Report to Congress on TMI 1terns. Submitted by NRC Chairman L. W. Zech Jr to Senator J. Glenn, Chairman, Committee on Government Affairs, Letter of 23 January.
Rogovin M. et al. (1980) Report NUREG/CR-1250, Vol. I, U.S. Nuclear Regulatory Commission. Rubin D. M. (1981) The Three Mile lsland Nuclear Accident (T. H. Moss and D. L. Sills, Eds), Annals of the New York Academy of Sciences, Vol. 365, pp. 95-105. Slovic P., Fischhoff B. and Lichtenstein S. (1982) Accident at Three Mile Island: The Haman Dimensions (D. L. Sills, C. P. Wolf and V. B. Shelanski, Eds), pp. 11-19. Westview Press, Boulder. Sorenson et al. (1983) Report ORNL-5891, Oak Ridge National Laboratory for the U.S. NRC. Spangler M. B. (1985) Technology Assessment, Environmental Impact Assessment and Risk Analysis (Covello V. et al., Eds), pp. 917-952. NATO Advanced Study Institute, Springer-Verlag, Heidelberg, F.R.G. Spangler M. B. (1986) Report NUREG-1205, U.S. Nuclear Regulatory Commission. Taylor J. J. (1985) EPR1 J. March, 2-3. Walker P. et al. (1982) Proc. Workshop on Psychological Stress Associated with the Proposed Restart of Three Mile Island, Unit 1. Report NUREG/CP-0026, U.S. Nuclear
Regulatory Commission.
0306-4549/90 $3.00+0.00 Pergamon Press pie
LETTER TO THE EDITORSt T H R E E MILE ISLAND REVISITED (Received 11 January 1990)
The subject of the Three Mile Island accident holds my personal interest both as a scientist and as a native of York, Pennsylvania, a neighboring town to the reactor site. As a boy I swam and fished in the Susquehanna river, in which Three Mile Island is located, and as a staff member for the U.S. Nuclear Regulatory Commission (NRC), I became involved with severe accident policy issues in the aftermath of the TMI accident. I especially remember an official inspection tour of the TM1 site in 1973 while employed by the Atomic Energy Commission. At that time, no one I talked with on either side of the river was notably frightened or concerned about the prospect of a nuclear accident. One of my most vivid impressions was the fortress-like construction of the reactor containment building of the unfinished Unit-2, a silent testimony to one important feature of the defense-indepth philosophy in the design, construction and operation of nuclear power plants in America. Then came the major accident of 28 March, 1979 to this TMI unit, the worst accident in the history of nuclear power generation until Chernobyl. Although I understood the seriousness of the event, my assignment then at the NRC gave me no immediate responsibilities in connection with the ~Lccident. But from 1983 to 1985, as Special Assistant for Policy Development in the Office of Nuclear Reactor Regulation, I was involved in drafting, coordinating and editing inputs in the development of the NRC's Severe Accident Policy Statement (NRC, 1980, 1985a, b). This statement and its supporting rationale constituted a response to safety and regulatory issues identified in the Report o f the President's Commission on the Accident at Three Mile lsland (The Kemeny Report) (Kemeny et al., 1979) and the investigation commissioned by the NRC itself, Three Mile Island: A Report to the Commissioners and to the Public (the Rogovin Report) (Rogovin et al., 1980). It is with this background that I present the following discussion of the TMI accident, its causes, its major effects and what else we may yet learn from it.
BRIEF SCENARIO OF THE TMI ACCIDENT
The main accident precursor event was the clogging of the condensate demineralizing system and the inadvertent shutdown during maintenance to remove the clogging. This shutdown interrupted the flow of feedwater to the steam generator. This event is believed to be a partial "failure"
t An invited essay in a forthcoming anthology, The Continuiny Debate : Ethics and Nuclear Eneryy (F. S. Carney and A. Sherman, Eds). The Ethics and Public Policy Center, Washington, D.C.
of engineering design involving equipment not formally designated as "safety-related." The next potentially significant event was the failure of the safety-related emergency feedwater system that came on automatically as per design. However, two important valves were closed (because of human error), which prevented water essential to the functioning of the steam generator to reach its target until the problem was discovered 8 min later. Because of the operator recovery action in opening these valves, this mistake was unimportant to the eventual course of the accident, except possibly for its distracting effect on the operators, contributing to their inability to diagnose the true status of the accident in progress. The most vital equipment failure in terms of ultimate consequences came when the electromatic pilot-operated relief valve (PORV) did not close after properly opening to relieve pressure build-up in the primary coolant (water) system servicing the reactor core. Because of a lack of reliable indicators (a design failure) and a lack of understanding (a human failure), the fact that the PORV had not closed remained undetected and uncorrected for 2 h and 20 min. However, the damage from these equipment and human breakdowns extended long after corrective action was taken. The problem was that the operators did not recognize how much coolant water had been lost from the reactor core during the period the PORV was stuck in the open position. But even these events would not have been so grave were it not for the disastrous operator decision about 3 min into the accident to bypass the high-pressure injection emergency core cooling system (ECCS). As designed, the ECCS came on automatically with a drop in coolant pressure. Ironically, the operator action resulted from the mistaken belief that the ECCS bypass was needed to prevent a "loss of coolant accident" (LOCA) from happening. In truth, the stuck-open PORV already constituted a LOCA that eventually led to a steam void in the top of the reactor that ultimately uncovered part of the reactor core and led to fuel melt. When the operators succeeded in starting the reactor coolant pump about 13' h into the accident, the most critical part of the accident was essentially over. However, this fact was not recognized until several days later because of serious differences of opinion over the possible hazard posed by the hydrogen generated by overheating of the fuel rods. The hydrogen bubble scare led to a major evacuation on Friday 30 March, the third day of the accident. The utility had released radioactive gas early that morning in a manner indicating that utility personnel might not be in complete control. The release had prompted Pennsylvania Governor Richard Thornburgh to recommend that invididuals living within 10 miles of the plant stay indoors and that pregnant women and young children within 5 miles of the plant leave the area. This was followed by a press briefing by two NRC staff
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members. In responding to the question "Is a meltdown possible?" one staff member replies, "Yes, there is a possibility . . . . I think everyone technical would have to concede that if the reactor was depressurized, and the hydrogen bubble expanded, there is a possibility, not a likelihood, but a possibility that things could go wrong, or all the cooling systems quit." The regulator's dilemma in deciding on a response to "what-if" questions regarding possible scenarios of an accident in progress is extraordinarily difficult and personally hazardous. A candid reply, such as the one just stated, avoids the distrust that often results from concealment of information. But it also may drastically elevate the risk of creating profound psychological stress among the public in an exaggerated way that may be inimical to the public's own interests. Thus, there is cause to ponder whether paternalism (or elitism) in certain situations should be viewed with the suspicion or disdain it is sometimes accorded (Spangler, 1985). There was scientific debate during the TMI accident over the possibility that the hydrogen bubble might combine with oxygen and explode. At 3:41 p.m. on Friday afternoon, NRC Chairman Joseph I-Iendrie responded to Governor Thornburgh's query on the hydrogen bubble's explosive potential. His reassuring reply was, "There isn't any oxygen in there to combine with that hydrogen, so the answer, as far as I know, is pretty close to zero" (Rogovin et al., 1980). Yet it was not until after intense consultation with experts during the next 2 days that Hendrie and NRC Director Harold Denton were able to confirm the correctness of this view to the Governor at 8:45 p.m. on Sunday. The role of the media in relating the events on Friday is epitomized by the opening remarks by Walter Cronkite in his CBS evening (TV) news program : "The world has never known a day quite like today. It faced considerable uncertainties and dangers of the worst nuclear power plant accident of the atomic age. And the horror tonight is that it could get much worse. It is not an atomic explosion that is feared; the experts say that is impossible. But the specter was raised (of) perhaps the next most serious kind of nuclear catastrophe, a massive release of radioactivity. The Nuclear Reactor Regulatory Commission cited that possibility with an announcement that, while it is not likely, the potential is there for the ultimate risk of a meltdown at the Three Mile Island Atomic Plant outside Harrisburg, Pennsylvania" (Cronkite et al., 1979). Cronkite's remarks are regarded by many as an example of sensational journalism, focusing on such words as "horror," "specter" and "catastrophe." David Rubin, a member of the Public's Right to Know Task Force of the President's Commission on the Accident at TMI, defended Cronkite's introduction as an accurate summary of what was then known about the course of the accident : "The 'horror' of the situation getting much worse did not materialize, but Cronkite can hardly be blamed for that. He was only reporting concerns voiced by members of the nuclear establishment" (Rubin, 1981). Rubin noted that, by any measure, 30 March was a disturbing and confusing day for those living near the plant. One of the lessons learned from this experience was the need to expand our scientific understanding about nuclear accident progression phenomena, including the survivability of safety equipment under environmental conditions of a severe nuclear accident. This knowledge could improve equipment design and accident management capabilities that
would halt or limit the consequences of a severe accident. NRC's Severe Accident Research Plan of 1983 placed considerable emphasis on these needs (NRC, 1983a) and has produced useful results. CONSEQUENCES OF THE ACCIDENT What were the major health, economic and socio-political consequences of the accident? Regarding health consequences, the President's Commission (the Kemeny Report) concluded that the amount of radiation received by any one individual outside the plant was very low (Kemeny et al., 1979). It estimated that less than one (delayed) cancer fatality is likely to be induced by the accidental release of radionuclides at TMI. This effect would be undetectable among the 325,000 people projected to die of cancer from routine causes having nothing to do with the power plant in the population of over 2 million persons living within 50 miles of TMI. Genetic defects from the radiation are estimated to be similarly small and undetectable. Indeed, the extended life span study of the A-bomb survivors at Nagasaki and Hiroshima, who received far higher levels of radiation than the exposed individuals near TMI, reveals that it took a period of from 30 to 33 yr after the bomb explosion over Nagasaki before a statistically significant excess of cancer deaths occurred there (Kato and Schull, 1982). Moreover, studies of numerous health indicators for 105,000 children born between 1946 and 1980 to parents exposed to A-bomb radiation in these cities fail to confirm any harmful genetic effects (Committee for the Compilation of Materials on Damage Caused by the Atomic Bombs in Hiroshima and Nagasaki, 1981). An increase of 5-10% would have been expected based on theoretical methods of dose-effect estimation. The Kemeny Report also concluded that the most serious health effect of the TMI accident was severe mental stress, which was generally short-lived. The highest levels of stress were found among those living within 5 miles of TMI and in families with preschool children. One of the most unexpected results of the psychological research following the accident was that reactions tended to be extreme: some people were virtually oblivious to the potential gravity of the situation whereas others were traumatized by it (Flynn, 1982). Psychological stress also recurred in response to later events, namely the necessary venting of radioactive krypton gas following the accident, the proposed discharge of cleanup liquids into the Susquehanna River at such low radiation doses as to remain below the limits of EPA protection standards, and the regulatory action that permitted restart of the undamaged Unit 1 that was down for maintenance at the time of the TMI-2 accident. Although the NRC conducted a public workshop with invited experts to explore these matters (Walker et al., 1982) and the Department of Energy contracted for a study report on the social and psychological impacts of Unit I restart (Sorenson et al., 1983), the Supreme Court ultimately ruled that the NRC was not required to deal with the psychological stress issue in the restart of Unit 1 (Metropolitan Edison v. Pane, 1983). As to economic consequences of the TMI accident, a survey of the effect of the accident on property values based on sales in the vicinity of TMI showed very limited impact (Gamble and Downing, 1981). But the property damages and make-up (purchased) energy costs incurred by the utility (GPU) resulting from the accident have been quite severe. The GPU estimated the clean-up costs of Unit 2 at $965 million, of which $731 million has already been spent. Unit
Letter to the Editors 1 was not permitted by the NRC to operate for the period between March 1979 and October 1985 with estimated makeup energy penalties of $12-15 million per month. A similar rate of make-up energy penalty for the somewhat larger Unit 2 is still being incurred. Thus, the make-up energy penalties for both units from April 1979 to June 1987 total $2.6 billion (borne by the utility's customers) with more yet to come for Unit 2 outage. Other nuclear utilities also incurred millions of dollars of backfit costs following the TMI accident. However, an even greater impact is the accident's adverse effect on the prospects for new plant orders, plus large financial losses from the cancellation of dozens of plants in a partially constructed state (Spangler, 1986). As to socio-political consequences, it has been pointed out that the TMI accident stimulated an immediate rise in antinuclear fervor, especially among the sizable and tenacious opposition movement that existed prior to the accident (Slovic et al., 1982). The potential health risks incurred under nuclear systems were viewed as substantially greater than the health effects of alternative energy sources. This was a result of the involuntary and catastrophic nature of nuclear risks, as well as its attributes of newness and dread (Fischhoff et aL, 1978).
RESPONSIBILITY FOR THE ACCIDENT Both the Kemeny Report (Kemeny et al., 1979) and the Rogovin Report (Rogovin et al., 1980), among others, search for root causes of the accident and the identification of measures which, if they had been implemented on a timely and effective basis, might have prevented or limited the accident. These measures were so numerous and so institutionally diverse that, in truth, no one party (the NRC, the operating utility management, the plant operators, the reactor or plant vendors, and certain equipment manufacturers) could escape discredit for their failures. Certainly, blame for the reactor operators' errors is substantially mitigated by a number of factors for which others were responsible: (1) the inadequacy of operator training to diagnose and effectively manage a severe accident so as to limit its consequences, including an understanding of the severe accident risk importance of accident percursor events ; (2) the inadequacies of instrumentation to denote the open/closed position of key valves or the insufficiency of coolant water in the reactor vessel, etc. ; and (3) the inadequacy of control room design to improve operator effectiveness in handling emergencies, including computer-aided diagnostic capability (Jaffe, 1981). The Kemeny Report also laid stress on the nature of "mindsets" as a contributory cause of the TMI-2 accident (Kemeny et aL, 1979). After many years of operation of nuclear power plants, with no evidence that any member of the general public has been hurt, the belief that nuclear power plants are sufficiently safe grew into a conviction. One must recognize this to understand why many key steps that could have prevented the accident at Three Mile Island were not taken. The Commission is convinced that this attitude must be changed to one that says nuclear power is by its very nature potentially dangerous, and, therefore, one must continually question whether the safeguards already in place are sufficient to prevent major accidents. A comprehensive system is required in which equipment and human beings are treated with equal importance.
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The Rogovin Report took these criticisms by the Kemeny Report to heart along with the insights from its own investigation of the accident. The scope of its conclusions and recommendations included the following concerns: (I) systematic evaluation of operating experience and improvement in the regulation of operating reactors ; (2) strengthening the onsite technical and management capability of the utility: improved operator training and new NRC requirements for qualified engineer supervisors on every shift; (3) greater application of human factors engineering, including better instrumentation display and improved control room design ; (4) more remote siting and improved emergency planning, including workable evacuation planning as a condition of reactor operation ; (5) overhaul of the licensing process : onestage licensing, increased standardization, increased use of rulemaking; and (6) improvement in the bases for safety review of reactor design and increased use of quantitative risk assessment techniques (Rogovin et al., 1980). These and other reports (NRC, 1980a, b) led to a massive effort imposed on utilities to backfit certain equipment changes and to implement numerous procedures involving maintenance and operation of their nuclear power plants. As noted in a recent One Time Report to Congress, the 151 utility implementation tasks identified by NRC and the three other items have resulted in a total of 6531 implementation actions (NRC, 1987). Of these, 5900, or about 90%, have been completed at the 65 plants operating at the time of the TMI accident. By the end of the calendar year 1989, all but 16 tasks will be implemented at all 65 reactors. This will equate to about 6200 implementation actions completed by the licensees or about 95% of the total requirements at these plants. Having been charged with under-regulating on behalf of safety, the NRC staffzealously pursued the above exhaustive list of tasks. This soon raised questions about the possibility of over-regulating on behalf of safety (NRC, 1981). The promotion of nuclear power, of course, is not a function of the Nuclear Regulatory Commission. Indeed, the Energy Reorganization Act of 1974, which established the NRC, made it quite clear that the agency's primary responsibility is the regulation of commercial nuclear power so as to assure adequate protection of public safey and health. Nevertheless, it seems reasonable that Congress did not intend regulatory policies, practices and decisions to be made in a manner that would be "anti" nuclear power, such as by employing regulatory practices that would yield small marginal gains in safety benefits in return for unreasonable costs, or would cause unconscionable or unwarranted delays or regulatory uncertainties that would deter utilities and the financial community from seriously considering the nuclear option (Denton, 1983). One of the important tools to achieve an appropriate balance between under- and over-regulation is the establishment of safety goals and, in particular, a safety-cost trade-off criterion. The Kemeny Report (Kemeny et al., 1979) recommended that "Included in the (NRC's) general substantive charge should be the requirement to establish and explain safety-cost trade-offs; where additional safety improvements are not clearly outweighed by cost considerations, there should be a presumption in favor of the safety change." It has also been recognized (Denton, 1986) that more careful attention should be given to the rationalization of the separate and cooperative roles of government and industry that would provide an optimal combination of safety and economy for the future of nuclear power in serving the national interests.
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LESSONS
TO BE LEARNED
FROM MISTAKES
MADE
In the early days of commercial nuclear power, enthusiasts clearly expected, with some justification, that this technology would become the wave of the future. According to 1974 forecasts of the U.S. Atomic Energy Commission (AEC, 1974). 1000 such olants would be oueratine in the U.S. bv the turn of the century. It was believed That this “technological goose” was destined to lay an abundance of golden eggs for the benefit of humankind, or so the enthusiasts firmly believed. Then a tidal change occurred. Although the 109 licensed nuclear plants in the U.S. today operate with comparatively low fuel costs, there have been no new nuclear power plants ordered since 1978. As of 1 January 1987, a total of 114 plants previously ordered have been cancelled. Many feel that the nuclear industry’s goose has been cooked before it had a chance to lay the promised golden eggs. They point to the public fear created by the accidents at TM1 and Chernobyl and the rising capital costs of nuclear plants because of regulatory delays and the expense of technology fixes on behalf of safety improvements following TMI. Yet I believe a different scenario for future nuclear power developments in the U.S. is still possible, however improbable it may seem today. Ironically, if the nuclear industry and its regulators had set out in the period before the midEast oil embargo in October 1973 to design a “developmental” scenario to sabotage the chances for success of nuclear technology in America, it could well have done so by fostering the very mistakes in strategic planning and prescience that have actually transpired. Ten important mistakes that contributed to the TM1 accident and the public’s perception of the desirability of nuclear energy were : 1. LA many flowers bloom--In the U.S. laissez faire system of government it was not practical to legislate (nor to mandate through regulation) a standard plant design approach even if its importance had been properly understood in this early period. Although private industry normally pursues strategic planning functions, nothing emerged from industry during those days to call attention to, or to effectively thwart, the disastrous effects on safety practices, the regulatory inefficiences, and the diseconomies in plant construction that would arise from the uncontrolled proliferation of custom designs of nuclear power plants. 2. Vesting the primary responsibility for safety in a regulatory agency-However appealing this approach may sound in theory, in practice it is self-defeating. This is not to say that a regulatory agency does not have an important, and even vital, role for assuring safety. But the tendency of regulatory agencies to establish minimum acceptable standards of technological and managerial performance on behalf of safety serves to inhibit the very pursuit of excellence by those responsible for the design, construction, operation and maintenace of nuclear plants, unless these parties understand that theirs is the primary responsibility for achieving safety. 3. The initial weak role of utilities-The
corollary to the above mistake is that many utilities, in the early stages of the nuclear industry, were only too willing to play a subordinate role in supervising the design and construction of nuclear power plants and in strategizing safety practices for their operation and maintenance. It may have been slick sales practices for vendors to tell potential utility customers that a nuclear reactor is “just another way of boiling water” at a time when
they held this high technology in awe. But the utilities’ willingness to be spoon-fed safety procedures and practices was unwise in the extreme. 4. Excessive
adversariahsm
in the regulatory decision
process-A certain amount of adversary or debate can be quite productive in serving or protecting societal values and interests. However, the adversarial relations that often developed between regulators (the AEC and subsequently the NRC) and the regulated industry (utilities and vendors), as well as with individuals and public interest groups who were intervenors at licensing and safety hearings, were often excessive, poorly-controlled and hence counterproductive to the interests of society. 5. Inadequate severe accident safety research-Although considerable safety research was mounted by the government (and supplemented by industry), many features of NRC’s Severe Accident Research Plan of 1983 (NRC, 1983) should have been established at a much earlier stage of the industry’s development. 6. Insujicient attention to technology transfer-In the development of complex technologies, the effectiveness of transferring “hands-on” learning experiences from the mistakes and best practices of those who implement technologies is essential to accelerate leaming curves that achieve industry-wide improvements in the cost, safety and the ultimate benefits to society of a given technology. The nuclear industry was slow to transfer the technological lessons of systems reliability engineering, human factors engineering, and control room design from the more advanced aerospace and defense industry. Perhaps even worse, the proliferation of custom plant designs (the failure to standardize) worked strongly against the transfer of “learning curve” experience from one unit of the industry to others, a practice now recognized to be in their mutual interest. 7. The failure of forecasts-While we cannot expect perfection in the hazardous art of forecasting, the excessive projections of electrical energy demand, and the rapid escalation of all fuel prices following the mid-East oil embargo (which fostered energy conservation), exacted severe penalties (as much as 100%) on nuclear power plant construction costs. Excessive generating capacity and reserve margins of utilities, because of overforecasting of demand, yielded both multi-year stretchouts in construction for both coal and nuclear plants and cancellation of new units. Had correct forecasts been made, this would have produced a reduced rate of plant orders. It would also have led to a much less chaotic stress on limited industry and regulatory resources, with more attention to the training of the new requisite skills that were in short supply. 8. The failure to solve waste management problems on a timely basis-Provisions for the permanent storage of
high-level wastes were seen as postponable in the early days when many plants were first being constructed and spent fuel reprocessing was envisioned as part of the “game plan.” 9. The failure to educate the public on the comparative safety and benefits of nuclear energy-The responsi-
bility for performing this function was quite diffused and unorganized. I suspect the main reason NRC does not today play a more vigorous role in this function is the desire to avoid an image of promotionalism. Yet the requirement of the National Enviornmental Policy
Letter to the Editors Act in making risk-cost-benefit analysis of alternatives does generate useful information related to this need. Shortcomings in public understanding of such issues can be viewed only as a major impediment to the solution of the nuclear industry's problems. 10. The failure to anticipate the public and political opposition to nucelar energy arising from all o f the above failures. IS THE TMI BONE OUT OF THE NATION'S THROAT?. As previously noted, most of the needed safety changes for both new and on-line reactors have now been determined and completed. Moreover, many of the industry and regulatory philosophies or approaches that led to failure have either been resolved or are well on their way to resolution. Thus, it is fair to ask, "Is the TMI accident bone now out of the nation's throat?" Not completely, I believe. There are two requirements that still must be met. First, it is necessary to demonstrate to the public and to investors that nuclear power plants can be operated more safely. This must include a notable reduction in the frequency of the more significant accident precursor events at nuclear plants, events that cause defense-in-depth engineered safety features to operate and that become newsworthy events in the local and national media. It is true, programs and industry organizations have emerged to deal more effectively with severe accident issues.t The second requirement to get the TMI bone out of the nation's throat is that it must be demonstated quite convincingly that a new nuclear power plant, when ordered, can be constructed on a controlled schedule and at a cost that restores the significant economic advantage relative to alternative sources of energy that nuclear power once had in the U.S. (and still has in several nations in the world employing reactors of basic U.S. technological design). One of the "wrong lessons" from TMI that many of the public and some investors perceive is that the cost escalation of nuclear power plants following TMI is necessarily a permanent part of the cost structure of nuclear power. The centerpiece of any effective strategy to meet these requirements is the successful adoption of the standardization approach to nuclear plant design. It will be necessary that industry pursue a standardized rather than a custom design approach. The utilities now appear to have universally accepted the view that standardization is the only approach capable of demonstrating that future U.S. nuclear plants can be built and operated with acceptable safety and economy. It is important to note two countries firmly committed to the nuclear option, namely France and Japan, have successfully demonstrated that the standardization approach can achieve the twin goals of acceptable safety and economy. France, which now generates 70% of its electricity from nuclear fuel, routinely builds standard nuclear plants of basic U.S. design within 6 yr. And Japan, the only country to have experienced the immediate and delayed adverse health effects of radiation from the A-bombs, has overcome its public fears of nuclear energy through a now-famed "pursuit-oft These include the Institute for Nuclear Power Operations (INPO), the Nuclear Safety Analysis Center (a part of the Electric Research Power Institute) and the Industry Degraded Core Rulemaking (IDCOR) Program under the sponsorship of nuclear utilities and coordinated by the Atomic Industrial Forum.
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excellence" philosophy in achieving demonstrable nuclear safety by limiting accident precursor failures. Quite encouragingiy, the U.S. is now actively pursuing two quite contrasting approaches in developing safer and more economical new standard plant designs. The first of these is the Advanced Light Water Reactor design (ALWR) being developed by the Electric Power Research Institute (Taylor, 1985). The safety improvements sought for the mid1990s would be evolutionary changes based on the best available features of proven technology of current pressurized water reactor (PWR) and boiling water reactor (BWR) designs. The second approach, being sponsored by the U.S. Department of Energy in conjunction with private contractors, is the development of three advanced reactor designs: a Modular High Temperature Gas-cooled Reactor (MHTGR), a Sodium Advanced Fast Reactor (SAFR) and a liquid metal reactor (Power Reactor Inherently Safe Module called PRISM). More radical in concept, this approach combines certain inherently safe design features with potential market advantages of small modular units. The modules could hopefully be more economically manufactured at central factories than the large-scale LWRs requiring a higher proportion of their construction to occur onsite where less predictable and less controllable factors of project management may contribute to cost overruns. Belatedly, the U.S. has recognized the folly of its early love affair with custom plant designs. Perhaps it will yet be possible to test what success the U.S. can achieve in harnessing the atom both safely and economically for commercial electricity production by adopting a standardization approach and other appropriate strategies. The potential benefits of such strategies became clearer through the agonizing introspection caused by the TMI accident and its follow-up programs. It is a sad fact of history that the most important lessons are often learned after the tragedies of preventable accidents. It is left to history to answer whether the TMI injury will yet aid the nuclear "goose" to lay some of the golden eggs that were prematurely expected of it. Techno-Planning, Inc. 9115 McDonald Drive, Bethesda MD 20817, U.S.A.
MILLER B. SPANGLER
REFERENCES
AEC (1974) Report WASH-I174-74, U.S. Atomic Energy Commission. Committee for the Compilation of Materials on Damage Caused by the Atomic Bombs in Hiroshima and Nagasaki (1981) Hiroshima and Nagasaki: The Physical, Medical and Social Effects of the Atomic Bombing. Basic Books, New York. Cronkite W. et al. (1979) CBS Evening News with Walter Cronkite, 30 March. Columbia Broadcasting System, New York. Denton H. R. (1983) The Energy J. 4, 125-141. Denton H. R. (1986) Nucl. Engng Des. 92, 303-322. Fischhoff B. and Slovic P. et al. (1978) Policy Sci. 9, 127-152. Flynn C. B. (1982) Accident at Three Mile Island: The Human Dimensions (D. L. Sills, C. P. Wolf and V. B. Shelanski, Eds), pp. 49-63. Westview Press, Boulder. See also Report NUREG/CR-2749, U.S. Nuclear Regulatory Commission. Gamble H. B. and Downing R. H. (1981) Report NUREG/ CR-2063, U.S. Nuclear Regulatory Commission. Jaffe L. (1981) The Three Mile Island Nuclear Accident:
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Lessons andlmplications (T. H. Moss and D. L. Sills, Eds), Annals of the New York Academy of Sciences, Vol. 365,
pp. 37-47. Kato H. and Schull W. J. (1982) Radiat. Res. 90, 395-432. Kemeny J. et al. (1979) Report on the President "sCommission on the Accident at Three Mile Island: The Need for Change. U.S. Govt Printing Office, Washington, D.C.
Metropolitan Edison v. Pane (1983) Report 460 USC 766. NRC (1980a) Report NUREG-0660, U.S. Nuclear Regulatory Commission. NRC (1980b) Report NUREG-0737, U.S. Nuclear Regulatory Commission. NRC (1981) Report NUREG-0839, U.S. Nuclear Regulatory Commission. NRC (1983) Report NUREG-0900, U.S. Nuclear Regulatory Commission. NRC (1985a) Federal Register 50(153), 32138-32151. NRC (1985b) Report NUREG-1070, U.S. Nuclear Regulatory Commission. NRC (1987) One Time Report to Congress on TMI 1terns. Submitted by NRC Chairman L. W. Zech Jr to Senator J. Glenn, Chairman, Committee on Government Affairs, Letter of 23 January.
Rogovin M. et al. (1980) Report NUREG/CR-1250, Vol. I, U.S. Nuclear Regulatory Commission. Rubin D. M. (1981) The Three Mile lsland Nuclear Accident (T. H. Moss and D. L. Sills, Eds), Annals of the New York Academy of Sciences, Vol. 365, pp. 95-105. Slovic P., Fischhoff B. and Lichtenstein S. (1982) Accident at Three Mile Island: The Haman Dimensions (D. L. Sills, C. P. Wolf and V. B. Shelanski, Eds), pp. 11-19. Westview Press, Boulder. Sorenson et al. (1983) Report ORNL-5891, Oak Ridge National Laboratory for the U.S. NRC. Spangler M. B. (1985) Technology Assessment, Environmental Impact Assessment and Risk Analysis (Covello V. et al., Eds), pp. 917-952. NATO Advanced Study Institute, Springer-Verlag, Heidelberg, F.R.G. Spangler M. B. (1986) Report NUREG-1205, U.S. Nuclear Regulatory Commission. Taylor J. J. (1985) EPR1 J. March, 2-3. Walker P. et al. (1982) Proc. Workshop on Psychological Stress Associated with the Proposed Restart of Three Mile Island, Unit 1. Report NUREG/CP-0026, U.S. Nuclear
Regulatory Commission.