A study of US nuclear power boiling water reactor, class IV, operating performance, 1992-1997
Author(s)Brodeur, David Lester, 1963-
Study of United States nuclear power boiling water reactor, class IV, operating performance, 1992-1997
Massachusetts Institute of Technology. Dept. of Nuclear Engineering.
Neil E. Todreas.
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The steady improvement of US Nuclear Utility generation capability observed over the past two decades has recently halted and somewhat degraded. For the industry to resume its upward trend in performance a detailed examination must be performed of current performance and new methods developed to continue the improvement. A detailed study of Boiling Water Reactor, Class IV (BWR/4) performance over the past five years was conducted to gain insight to the nature of lost generation capability and develop a methodology to improve capability. Extensive electronic NRC records were used in conjunction with detailed power plant records and engineering experience at PECO Energy's Limerick Generating Station and Peach Bottom Atomic Power Station for this research. Administrative or regulatory shutdowns within the study dominated the lost generation capability and detracted from the goal of analyzing equipment reliability. Nine of two hundred thirty five shutdowns were therefore limited to maximum impact of 30 days lost generation. Balance of Plant system failures were found to initiate 69% of the occurrences of lost generation capability and account for 59% of the capability loss. The failures of these systems were found to be infrequent events which correlated poorly to the aggregate industry experience. Approximately fifty percent of the forced outages were the result of equipment related failures such as weak design or worn parts with the remaining fifty percent the result of human related failures. Only 19% of the failures were noted to be the result of component age related failures while 31% of the failures were related to poor equipment design. The time frame of forced outages with in operating cycles was additionally reviewed. Failures were found to be more frequent in the early phase of the operating cycle following start up from a refueling and approximately 400 to 550 days after start up. The impact of these failures was not great enough to affect the steady state cumulative capability factor of the aggregate BWR/4 utility achieved after one year of operation. Individual utility sites were found to have opposing strong and weak periods of performance within their operating cycles. The loss of generation capacity taken for planned maintenance outages and on line maintenance for minor equipment problems was not found to have a significant impact on aggregate BWR/4 performance. For plants not involve in lengthy shutdowns, the strongest impacts on cumulative capacity were forced outages, initial start up and coast down. The unpredictable and design nature of system failures necessitates a structured effort to improve the combined performance of all systems at a utility. Balance of Plant systems were found to all have a 25% probability of causing a single forced outage lasting slightly less than 5 days in length. The infrequent nature of significant failures necessitates a broad based communication between utilities to maintain an adequate level of awareness of system vulnerabilities and possible improvements. Two specific sites examined had opposing and repeatable strong and weak cycle performance traits. The unique nature of site performance demonstrates the impact that improved communications between utilities could have on transferring strengths and diminishing weaknesses thus improving overall utility performance.
Thesis (Nucl.E. and S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1998.Includes bibliographical references.
DepartmentMassachusetts Institute of Technology. Dept. of Nuclear Engineering.
Massachusetts Institute of Technology