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Cycle 7 outage experience. [Fast Flux Test Facility (FFTF)]

Description: The scheduled 58-day refueling outage in preparation for the seventh operating cycle of the Fast Flux Test Facility (FFTF) was successfully completed three days ahead of schedule. The planning and execution of the outage was greatly aided by Project/2 automated scheduling capabilities. For example, the use of ''maintenance windows'' and resource loading capabilities was particularly effective. The value of the planning process was demonstrated by the smooth transition into the outage phase afte… more
Date: March 1, 1986
Creator: Gadeken, A.D.
Partner: UNT Libraries Government Documents Department
open access

Risk-Based Plant Performance Indicators

Description: Tasked by the 1979 President's Commission on the Accident at Three Mile Island, the US nuclear power industry has put into place a performance indicator program as one means for showing a demonstrable record of achievement.'' Largely through the efforts of the Institute of Nuclear Power Operations (INPO), plant performance data has, since 1983, been collected and analyzed to aid utility management in measuring their plants' performance progress. The US Nuclear Regulatory Commission (NRC) has al… more
Date: January 1, 1989
Creator: Boccio, J. L.; Azarm, M. A.; Vesely, W. E. & Hall, R. E.
Partner: UNT Libraries Government Documents Department
open access

Systems interaction study of a Westinghouse PWR

Description: This paper presents methods and findings of a systems interaction study of Indian Point 3. The study was carried out in support of the resolution of Unresolved Safety Issue A-17 on Systems Interactions. Fault tree methods were employed. Among the study's findings is a single active failure in the low pressure injection function; this discovery led to a plant modification. In addition to providing support to the staff in resolving USI A-17, the project discovered an important new class of failur… more
Date: January 1, 1985
Creator: Youngblood, R.; Hanan, N.; Fitzpatrick, R.; Xue, D.; Bozoki, G.; Fresco, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Probabilistic analysis of allowed outage times relaxation at a PWR plant

Description: Technical Specifications (TS) in a nuclear power plant are specific requirements on its day-to-day operation, designed to protect public health and safety. Two primary aspects of the TS are (1) limiting conditions of operation (LCO) with allowed outage times (AOTs) and (2) surveillance testing intervals (STIs). In recent years, there has been growing interest in the nuclear community in reexamining the TS. One of the reasons is that a significant portion of reactor downtime (plant unavailabilit… more
Date: January 1, 1986
Creator: Cho, N.; Chu, T.; Xue, D.; Bozoki, G. & Youngblood, R.
Partner: UNT Libraries Government Documents Department
open access

Strategies and criteria for risk-based configuration control

Description: A configuration, as used here, is a set of component operability or statuses that define the state of a nuclear power plant. Risk-based configuration control is the management of component configurations using a risk perspective to control risk and assure safety. If the component configurations that have high risk implications do not occur then the risk from the operation of nuclear power plants would be minimal. The control of component configurations, i.e., the management of component statuse… more
Date: January 1, 1991
Creator: Samanta, P.K.; Kim, I.S. (Brookhaven National Lab., Upton, NY (United States)) & Vesely, W.E. (Science Applications International Corp., San Diego, CA (United States))
Partner: UNT Libraries Government Documents Department
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Flooding Experiments and Modeling for Improved Reactor Safety

Description: Countercurrent two-phase flow and “flooding” phenomena in light water reactor systems are being investigated experimentally and analytically to improve reactor safety of current and future reactors. The aspects that will be better clarified are the effects of condensation and tube inclination on flooding in large diameter tubes. The current project aims to improve the level of understanding of flooding mechanisms and to develop an analysis model for more accurate evaluations of flooding in the … more
Date: September 14, 2008
Creator: Solmos, M., Hogan, K.J., VIerow, K.
Partner: UNT Libraries Government Documents Department
open access

Reliability of the Solar One plant during the power production phase.

Description: Solar One is the world's largest central receiver power plant. During the last 4 years the plant availability was 80%, 83%, and 96%, respectively, during hours of sunshine. This reliability is considered to be excellent considering the plant is a first-of-a-kind facility and because it has been subjected to daily cyclic service. In this paper we present the frequencies and causes of the plant outages that occurred. The ten most important causes comprised 72% of the total outage time. Qualitativ… more
Date: January 1, 1989
Creator: Kolb, Gregory J. & Lopez, Charles W.
Partner: UNT Libraries Government Documents Department
open access

Development of alternate visual examination requirements for dynamic restraints (snubbers)

Description: Current plant technical specifications require an initial inservice visual examination of safety related equipment dynamic restraints (snubbers) to provide assurance of operability. The time to the next examination is as short as 1 month if 8 or more snubbers are found to be inoperable. Plant operators have observed that as the snubber population of a plant increases, the current plan becomes burdensome by requiring frequent shutdowns for examination of snubbers. The Nuclear Regulatory Commissi… more
Date: January 1, 1989
Creator: Reich, M.; Breidenbach, G. & Grossman, W.
Partner: UNT Libraries Government Documents Department
open access

System transient response to loss of off-site power

Description: A simultaneous trip of the reactor, main circulation pumps, secondary coolant pumps, and pressurizer pump due to loss of off-site power at the High Flux Isotope Reactor (HFIR) located at the Oak Ridge National Laboratory (ORNL) has been analyzed to estimate available safety margin. A computer model based on the Modular Modeling System code has been used to calculate the transient response of the system. The reactor depressurizes from 482.7 psia down to about 23 psia in about 50 seconds and rema… more
Date: January 1, 1990
Creator: Sozer, A.
Partner: UNT Libraries Government Documents Department
open access

Pair importance measures in systems analysis

Description: Importance measures in systems unreliability (or unavailability) analysis provide useful information in identifying components which are critical with regard to the availability or reliability of a system. Various importance measures known in the reliability literature are defined for a single component. This paper extends previous work to define importance measures for a pair of components of the system (accident sequence, core damage frequency, or health risks as appropriate), and illustrates… more
Date: January 1, 1986
Creator: Youngblood, R.; Xue, D. & Cho, N.
Partner: UNT Libraries Government Documents Department
open access

Probabilistic evaluation of limiting conditions of operations outage times for diesel generators

Description: This paper presents the results of two approaches for quantitative evaluation of Limiting Conditions of Operations for Outage Times for Diesel Generators. The first approach calculates the core damage frequency conditional on the state of the Emergency ac System (EAC). These conditional frequencies can be used to determine appropriate Allowable Outage Times (AOTs). Four representative EAC systems are analysed; one with four, two with three and one with two diesel generators. The results indicat… more
Date: January 1, 1985
Creator: Papazoglou, I. A.; Bozoki, G. E. & Sun, Y. H.
Partner: UNT Libraries Government Documents Department
open access

Risk-based evaluation of Allowed Outage Times (AOTs) considering risk of shutdown

Description: When safety systems fail during power operation, Technical Specifications (TS) usually limit the repair within Allowed Outage Time (AOT). If the repair cannot be completed within the AOT, or no AOT is allowed, the plant is required to be shut down for the repair. However, if the capability to remove decay heat is degraded, shutting down the plant with the need to operate the affected decay-heat removal systems may impose a substantial risk compared to continued power operation over a usual repa… more
Date: January 1, 1992
Creator: Mankamo, T. (Avaplan Oy, Espoo (Finland)); Kim, I.S. & Samanta, P.K. (Brookhaven National Lab., Upton, NY (United States))
Partner: UNT Libraries Government Documents Department
open access

Results and insights from the low power and shutdown Level 1 PRA of the Grand Gulf Nuclear Power Station

Description: The US Nuclear Regulatory Commission`s Office of Nuclear Regulatory Research has undertaken a two-phase project to analyze the frequencies, consequences, and risk of accidents occurring during modes of operation other than full power (i.e., low power and shutdown (LP&S) conditions). The Phase 1 work represented a ``coarse screening`` of all identified modes of operation. The results were used to identify which set of plant operating conditions would be subjected to a detailed analysis during Ph… more
Date: November 1, 1993
Creator: Whitehead, D. W.; Staple, B. D.; Daniel, S. L.; Darby, J.; Miller, S.; Forester, J. et al.
Partner: UNT Libraries Government Documents Department
open access

Handbook of methods for risk-based analysis of Technical Specification requirements

Description: Technical Specifications (TS) requirements for nuclear power plants define the Limiting Conditions for Operation (LCOs) and Surveillance Requirements (SRs) to assure safety during operation. In general, these requirements were based on deterministic analysis and engineering judgments. Experiences with plant operation indicate that some elements of the requirements are unnecessarily restrictive, while others may not be conducive to safety. Improvements in these requirements are facilitated by th… more
Date: December 31, 1993
Creator: Samanta, P. K. & Vesely, W. E.
Partner: UNT Libraries Government Documents Department
open access

Results and insights of a level-1 internal event PRA of a PWR during mid-loop operations

Description: Traditionally, probabilistic risk assessments (PRA) of severe accidents in nuclear power plants have considered initiating events potentially occurring only during full power operation. Some previous screening analysis that were performed for other modes of operation suggested that risks during those modes were small relative to full power operation. However, more recent studies and operational experience have implied that accidents during low power and shutdown could be significant contributor… more
Date: December 31, 1993
Creator: Chu, T. L.; Musicki, Z. & Kohut, P.
Partner: UNT Libraries Government Documents Department
open access

Risk-based configuration control: Application of PRA in improving technical specifications and operational safety

Description: The objective of risk-based configuration control is to detect and control plant configurations form a risk perspective. The configurations of particular interest involve components which are down during power operation. Controlling plant configurations from a risk-perspective can provide more direct risk control and also more operational flexibility by allowing looser control in areas unimportant to risk.
Date: December 31, 1991
Creator: Samanta, P. K.; Kim, I. S. & Vesely, W. E.
Partner: UNT Libraries Government Documents Department
open access

The impact of safety analyses on the design of the Hanford Waste Vitrification Plant

Description: Accident analyses are being performed to evaluate and document the safety of the Hanford Waste Vitrification Plant (HWVP). The safety of the HWVP is assessed by evaluating worst-case accident scenarios and determining the dose to offsite and onsite receptors. Air dispersion modeling is done with the GENII computer code. Three accidents are summarized in this paper, and their effects on the safety and the design of the HWVP are demonstrated.
Date: April 1, 1993
Creator: Koppenaal, T. J.; Yee, A. K.; Reisdorf, J. B. & Hall, B. W.
Partner: UNT Libraries Government Documents Department
open access

Markov Model of Accident Progression at Fukushima Daiichi

Description: On March 11, 2011, a magnitude 9.0 earthquake followed by a tsunami caused loss of offsite power and disabled the emergency diesel generators, leading to a prolonged station blackout at the Fukushima Daiichi site. After successful reactor trip for all operating reactors, the inability to remove decay heat over an extended period led to boil-off of the water inventory and fuel uncovery in Units 1-3. A significant amount of metal-water reaction occurred, as evidenced by the quantities of hydrogen… more
Date: November 11, 2012
Creator: Cuadra, A.; Bari, R.; Cheng, L. Y.; Ginsberg, T.; Lehner, J.; Martinez-Guridi, G. et al.
Partner: UNT Libraries Government Documents Department
open access

Outage management: A case study

Description: Outage management issues identified from a field study conducted at a two-unit commercial pressurized water reactor (PWR), when one unit was in a refueling outage and the other unit was at full power operation, are the focus of this paper. The study was conduced as part of the US Nuclear Regulatory Commission`s (NRC) organizational factors research program, and therefore the issues to be addressed are from an organizational perspective. Topics discussed refer to areas identified by the NRC as c… more
Date: September 1, 1992
Creator: Haber, S. B.; Barriere, M. T. & Roberts, K. H.
Partner: UNT Libraries Government Documents Department
open access

Cost of Power Interruptions to Electricity Consumers in the United States (U.S.)

Description: The massive electric power blackout in the northeastern U.S.and Canada on August 14-15, 2003 catalyzed discussions about modernizingthe U.S. electricity grid. Industry sources suggested that investments of$50 to $100 billion would be needed. This work seeks to better understandan important piece of information that has been missing from thesediscussions: What do power interruptions and fluctuations in powerquality (power-quality events) cost electricity consumers? We developed abottom-up approa… more
Date: February 16, 2006
Creator: Hamachi LaCommare, Kristina & Eto, Joseph H.
Partner: UNT Libraries Government Documents Department
open access

Impact of Uncertainty on Calculations for Recovery from Loss of Offsite Power

Description: Uncertainty, both aleatory and epistemic, can have a significant impact on estimated probabilities of recovering from loss of offsite power within a specified time window, and such probabilities are an input to risk-informed decisions as to the significance of inspection findings in the U.S. Nuclear Regulatory Commission’s Reactor Oversight Process. In particular, the choice of aleatory model for offsite power recovery time can have a significant impact on the estimated nonrecovery probability,… more
Date: June 1, 2010
Creator: Kelly, Dana L.
Partner: UNT Libraries Government Documents Department
open access

Proposed SPAR Modeling Method for Quantifying Time Dependent Station Blackout Cut Sets

Description: Abstract: The U.S. Nuclear Regulatory Commission’s (USNRC’s) Standardized Plant Analysis Risk (SPAR) models and industry risk models take similar approaches to analyzing the risk associated with loss of offsite power and station blackout (LOOP/SBO) events at nuclear reactor plants. In both SPAR models and industry models, core damage risk resulting from a LOOP/SBO event is analyzed using a combination of event trees and fault trees that produce cut sets that are, in turn, quantified to obtain a… more
Date: June 1, 2010
Creator: Schroeder, John A.
Partner: UNT Libraries Government Documents Department
open access

What organizations did (and didn't) do: Three factors that shaped conservation responses to California's 2001 'crisis'

Description: Beginning in the summer of 2000, California experienced energy supply problems, sharp increases in electricity and natural gas prices, and isolated blackouts. In response, California's state government implemented an unprecedented energy conservation effort to mitigate projected electricity supply shortages during the summer of 2001. Ultimately, significant electricity demand and consumption reductions were achieved. This paper considers the response of commercial and institutional organization… more
Date: August 18, 2002
Creator: Janda, Kathryn; Payne, Christopher; Kunkle, Rick & Lutzenhiser, Loren
Partner: UNT Libraries Government Documents Department
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