Revitalizing Nuclear Safety Research (1986) / Chapter Skim
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Elements of a Future Agenda for Nuclear Safety Research
Elements of a Future Agenda for Nuclear Safety Research
Pages 25-42
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From page 25... ...
The table presents in alphabetical order a selection of important topics requiring research. The committee was asked to review a draft report, "NRC Safety Research Program," by the staff of the NRG, which outlines a small number of research topics they wish to pursue -- component aging; thermal hydraulic transients; severe accidents; plant operations; seismic analysis; and waste disposal -- and a seventh (advanced reactors)
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From page 26... ...
CURRENT PLANT DESIGNS Behavior of Materials in Nuclear Power Plant Environments Many of the research topics discussed elsewhere in this chapter necessitate basic, exploratory, long-term research on materials used in the construction of nuclear power plant structures, systems, and components. Topics such as plant aging, component and system reliability, nondestructive testing and examination,
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From page 27... ...
It can and should be developed as a basis for future investigations of such issues as new fabrication processes for use during plant construction; corrosion and cracking of piping during normal operations; effects of pressure and temperature gradients and radiation extremes on piping and equipment; inspection frequency and inspection techniques; repair and maintenance procedures; occupational health and protection against radiation; and many other topics of relevance to plant safety, reliability, and maintainability. Basic and applied research on materials properties and the performance of materials in the different environments found in nuclear power plants are essential in providing a means of confirming the adequacy of existing operating parameters, inspection techniques, and operating and maintenance procedures.
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From page 28... ...
DOE shares part of the responsibility for decommissioning research not only because of its mission to conduct basic energy research but also because it has reactors that will soon require decommissioning. It currently is conducting a sizable program of research, the principal elements of which are the decommissioning of the demonstration reactor at Shippingport and the removal and analysis of the core of the damaged Three Mile Island reactor.
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From page 29... ...
At any time of the day or night, plant operators must be ready and able to diagnose disturbances in plant operations and prevent them from leading to a major accident. We now have enough operating experience to know that human errors are a significant contributor to the class of reportable events that occur at nuclear power plants, and we also know from probabilistic risk analyses that human errors are a significant contributor to plant risk.
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From page 30... ...
For this reason the federal government must establish a base program that encompasses these various areas and seek to play a leading role in encouraging the transfer of advanced technology for improving human reliability to the nuclear industry. At present, the NRC has almost no program whatsoever, and few national laboratories have much human factors expertise.
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From page 31... ...
Perhaps the crucial point to be made is that the NRC needs to establish a regulatory climate that encourages technological advances in the area of human factors, rather than one that is merely neutral with respect to it, as is now the case. DOE should fund and direct its contractors who operate DOE reactors to perform research in all of these areas, because the research is needed for the continued safety of DOE reactors, because it is largely developmental, and because new technology is not required for commercial reactors by existing regulations.
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From page 32... ...
The nuclear industry believes that this will be especially appropriate for those nuclear power plants where no major licensing issues are outstanding and where the capital cost of the facility has been fully paid off. Because the cost of capital is the major component of the cost of nuclear-generated electricity, electricity produced by such plants is relatively inexpensive.
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From page 33... ...
Examples of specific research topics in this field include in situ weld-repair techniques; structural integrity of plant systems, including the long-term integrity of radiation-embrittled materials; on-line diagnostics to measure degradation, including nondestructive testing; and the effectiveness of in-place annealing on the brittle fracture behavior of reactor pressure vessels. Policy Research One of the primary purposes of nuclear safety research, especially that funded or required by the NRC, is to inform regulatory decisions.
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From page 34... ...
Research is needed to develop techniques to evaluate the as-built condition of nuclear power plants, and to track these conditions over the life of the plants to ensure that repairs and modifications that were made to correct faulty conditions do not lead to future problems. Topics in this field include the reliability and efficiency of QA-QC practices, human factors in QA-QC, construction-induced anomalies and their repair, and QA-QC data base management.
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From page 35... ...
But the real purpose of a program to reevaluate the existing regulations is to rewrite the regulations so that they are more consistent and more efficient in ensuring public safety. Reliability of Plant Components and Plant Systems Nuclear power plants in the United States average many more reactor shutdowns per year than their Japanese and French counterparts.
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From page 36... ...
When properly applied, these methods can assist in interpreting operating experience, in analyzing data on the reliability of components and plant systems, and in identifying potential contributors to severe accidents. The development of PRA methodology necessarily resulted largely from generic studies of the elements of risk in nuclear plants and applications of the methodology to illustrative plants.
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From page 37... ...
Both industry and the NRC should fund research on PRA methodology, and the agenda should be set cooperatively. Seismology, Soil Mechanics, and Structural Response to Seismic Events Current estimates of the risk posed by earthquakes contain large uncertainties and suffer from the difficulty of modeling seismic phenomena.
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From page 38... ...
Civil engineers have tended to play a leading role as earth sciences advisors to industry. This basic difference in perspective between the two groups has led to and probably will continue to result in an inability of technical experts relied upon by the NRC, utilities, and intervenors to reach consensus on earth sciences regulatory issues.
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From page 39... ...
Long before the Soviet nuclear accident at Chernobyl, it was clear from severe accident research that the major source of risk to the public stems from accident sequences that threaten the integrity of reactor containment structures. One of the principal goals of future severe accident research should be to establish containment performance, and this will require further basic research on the physical and chemical processes relevant to severe accidents that might breach containment.
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From page 40... ...
Thermal Hydraulics Thermal hydraulics has been the dominant area of nuclear safety research since regulatory research began. Prior to the accident at Three Mile Island, nuclear safety research in thermal hydraulics was focused on reactor steady state conditions, reactor transients, and large-break, loss-of-coolant accidents.
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From page 41... ...
The United States must plan on being an active participant in these international programs for the long term. Although the utilities have in the past participated in international work of this kind, the international character of the work indicates that the NRC has the principal responsibility for funding and helping to set the agenda for international experimental thermal hydraulics research.
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From page 42... ...
It is poor public policy to have DOE and industry funding advanced reactor research and development while the NRC has failed to lay the regulatory basis for such reactors. The Commission's recent policy statement on advanced reactors fails to provide the program of regulatory research on advanced reactors with the detailed guidance that it requires.
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