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Operational readiness verification, phase 1: A study on safety during outage and restart of nuclear power plants

Abstract

This report contains the findings from the first phase of a study on safety during outage and restart of nuclear power plants. Operational Readiness Verification (ORV) - in Swedish called Driftklarhetsverifiering (DKV) - refers to the test and verification activities that are necessary to ensure that plant systems are able to provide their required functions when needed - more concretely that all plant systems are in their correct functional state when the plant is restarted after an outage period. The concrete background for this work is that nine ORV related incidents were reported in Sweden between July 1995 and October 1998. The work reported here comprised a literature survey of research relevant for ORV issues, and an assessment of the present situation at Swedish NPPs with respect to ORV. The literature survey was primarily aimed at research related to NPPs, but also looked at domains where similar problems have occurred, such as maintenance in commercial aviation. The survey looked specifically for organisational and MTO aspects relevant to the present situation in Swedish NPPs. One finding was that ORV should be seen as an integral part of maintenance, rather than as a separate activity. Another, that there is a characteristic distribution  More>>
Authors:
Hollnagel, E; [1]  Gauthereau, V [2] 
  1. Linkoeping Univ. (Sweden). Dept. of Computer and Information Science
  2. Linkoeping Univ. (Sweden). Dept. of Industrial Engineering
Publication Date:
Jun 01, 2001
Product Type:
Technical Report
Report Number:
SKI-R-01-47
Resource Relation:
Other Information: 57 refs, 14 figs, 6 tabs; PBD: Jun 2001
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; HUMAN FACTORS; MAN-MACHINE SYSTEMS; OUTAGES; REACTOR MAINTENANCE; REACTOR OPERATION; REACTOR SAFETY; REACTOR START-UP; RELIABILITY; REVIEWS; VERIFICATION
OSTI ID:
20238473
Research Organizations:
Swedish Nuclear Power Inspectorate, Stockholm (Sweden)
Country of Origin:
Sweden
Language:
English
Other Identifying Numbers:
Other: Project SKI 98157; ISSN 1104-1374; TRN: SE0200116012856
Availability:
Available from INIS in electronic form; Also available from: http://www.ski.se/se/index_publications_uk.html
Submitting Site:
SWDN
Size:
62 pages
Announcement Date:

Citation Formats

Hollnagel, E, and Gauthereau, V. Operational readiness verification, phase 1: A study on safety during outage and restart of nuclear power plants. Sweden: N. p., 2001. Web.
Hollnagel, E, & Gauthereau, V. Operational readiness verification, phase 1: A study on safety during outage and restart of nuclear power plants. Sweden.
Hollnagel, E, and Gauthereau, V. 2001. "Operational readiness verification, phase 1: A study on safety during outage and restart of nuclear power plants." Sweden.
@misc{etde_20238473,
title = {Operational readiness verification, phase 1: A study on safety during outage and restart of nuclear power plants}
author = {Hollnagel, E, and Gauthereau, V}
abstractNote = {This report contains the findings from the first phase of a study on safety during outage and restart of nuclear power plants. Operational Readiness Verification (ORV) - in Swedish called Driftklarhetsverifiering (DKV) - refers to the test and verification activities that are necessary to ensure that plant systems are able to provide their required functions when needed - more concretely that all plant systems are in their correct functional state when the plant is restarted after an outage period. The concrete background for this work is that nine ORV related incidents were reported in Sweden between July 1995 and October 1998. The work reported here comprised a literature survey of research relevant for ORV issues, and an assessment of the present situation at Swedish NPPs with respect to ORV. The literature survey was primarily aimed at research related to NPPs, but also looked at domains where similar problems have occurred, such as maintenance in commercial aviation. The survey looked specifically for organisational and MTO aspects relevant to the present situation in Swedish NPPs. One finding was that ORV should be seen as an integral part of maintenance, rather than as a separate activity. Another, that there is a characteristic distribution of error modes for maintenance and ORV, with many sequence errors and omissions, rather than a set of unique error modes. An international study further showed that there are important differences in how procedures are used, and in the balance between decentralisation and centralisation. Several studies also suggested that ORV could usefully be described as a barrier system in relation to the flow of work, for instance using the following five stages: (1) preventive actions during maintenance/outage, (2) post-test after completion of work, (3) pre-test before start-up, (4) the start-up sequence itself, and (5) preventive actions during power operation - possibly including automatic safety systems. In the field survey interviews were conducted with technical staff at most of the Swedish NPPs. It focused on which solutions the various NPPs had developed to cope with the problem, and which steps had been taken specifically to improve the efficiency of ORV. It was soon found that ORV could not be separated from the rest of the work done in a NPP during outages since many of the proposed solutions have a broad scope. An analysis of the nine Swedish ORV cases had found weaknesses in four main areas: administration processes, management, human performance, and control room layout. Relative to these, the Swedish NPPs have implemented several technical and organisational solutions. Among the former are an overall re-qualification scheme, blocked safety functions, computerised operational position control, and central indications in the control room. Most of the technical solutions have been part of the design of the newer plants, since to implement them in older plants requires essential changes both in the station and in the control room. The organisational solutions comprised operational readiness plans, systematic ways of working, new instructions, co-ordinated testing, and the use of redundant or independent controls. Special emphasis was put on how the NPPs planned their outages, how the plans were implemented, and how deviations were handled. Issues related to learning from experience were also investigated. It was found that although all the NPPs approached the ORV issues in a serious and efficient manner, the solutions could be different corresponding to the characteristics of the organisation. Finally a number of questions, which still need answers, were identified. One is how new procedures or new barriers are accepted and assimilated into the safety culture. A second concerns the demarcation of systems for which ORV is required, i.e., the boundary between safety and non-safety systems. A third is how complex technical solutions influence the operators' work. Finally, it is proposed to continue the study by looking more closely at the differences between three levels, or types, of tests: object test, system test and (safety) function test. This should aim to analyse the different steps of testing in order to understand the non-trivial relations between tests and safety. The study should take place at a single NPP during partial/sub-outages, since these periods allow empirical work to be conducted in an appropriate environment with better accessibility to technical staff than during full outage period.}
place = {Sweden}
year = {2001}
month = {Jun}
}