Component unavailability versus inservice test (IST) interval: Evaluations of component aging effects with applications to check valves

PDF Version Also Available for Download.

Description

Methods are presented for calculating component unavailabilities when inservice test (IST) intervals are changed and when component aging is explicitly included. The methods extend usual approaches for calculating unavailability and risk effects of changing IST intervals which utilize Probabilistic Risk Assessment (PRA) methods that do not explicitly include component aging. Different IST characteristics are handled including ISTs which are followed by corrective maintenances which completely renew or partially renew the component. ISTs which are not followed by maintenance activities needed to renew the component are also handled. Any downtime associated with IST, including the test downtime and the following maintenance ... continued below

Physical Description

270 p.

Creation Information

Vesely, W.E. & Poole, A.B. July 1, 1997.

Context

This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this report can be viewed below.

Who

People and organizations associated with either the creation of this report or its content.

Authors

Sponsor

Publishers

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this report. Follow the links below to find similar items on the Digital Library.

Description

Methods are presented for calculating component unavailabilities when inservice test (IST) intervals are changed and when component aging is explicitly included. The methods extend usual approaches for calculating unavailability and risk effects of changing IST intervals which utilize Probabilistic Risk Assessment (PRA) methods that do not explicitly include component aging. Different IST characteristics are handled including ISTs which are followed by corrective maintenances which completely renew or partially renew the component. ISTs which are not followed by maintenance activities needed to renew the component are also handled. Any downtime associated with IST, including the test downtime and the following maintenance downtime, is included in the unavailability evaluations. A range of component aging behaviors is studied including both linear and nonlinear aging behaviors. Based upon evaluations completed to date, pooled failure data on check valves show relatively small aging (e.g., less than 7% per year). However, data from some plant systems could be evidence for larger aging rates occurring in time periods less than 5 years. The methods are utilized in this report to carry out a range of sensitivity evaluations to evaluate aging effects for different possible applications. Based on the sensitivity evaluations, summary tables are constructed showing how optimal IST interval ranges for check valves can vary relative to different aging behaviors which might exist. The evaluations are also used to identify IST intervals for check valves which are robust to component aging effects. General insights on aging effects are also extracted. These sensitivity studies and extracted results provide useful information which can be supplemented or be updated with plant specific information. The models and results can also be input to PRAs to determine associated risk implications.

Physical Description

270 p.

Notes

INIS; OSTI as TI97007394

Source

  • Other Information: PBD: Jul 1997

Language

Item Type

Identifier

Unique identifying numbers for this report in the Digital Library or other systems.

  • Other: TI97007394
  • Report No.: NUREG/CR--6508
  • Report No.: ORNL--6909
  • Grant Number: AC05-96OR22464
  • DOI: 10.2172/505260 | External Link
  • Office of Scientific & Technical Information Report Number: 505260
  • Archival Resource Key: ark:/67531/metadc695336

Collections

This report is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

What responsibilities do I have when using this report?

When

Dates and time periods associated with this report.

Creation Date

  • July 1, 1997

Added to The UNT Digital Library

  • Aug. 14, 2015, 8:43 a.m.

Description Last Updated

  • April 8, 2016, 7:02 p.m.

Usage Statistics

When was this report last used?

Yesterday: 0
Past 30 days: 0
Total Uses: 2

Interact With This Report

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

Citations, Rights, Re-Use

Vesely, W.E. & Poole, A.B. Component unavailability versus inservice test (IST) interval: Evaluations of component aging effects with applications to check valves, report, July 1, 1997; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc695336/: accessed August 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.