On the reliability of fire detection and alarm systems

70 Pages·2005·2.11 MB·English

by  Timo Hellgren

ESPOO 2005 VTT WORKING PAPERS 18
On the reliability of fire
detection and alarm systems
Exploration and analysis of data from
nuclear and non-nuclear installations
Teemu Nyyss(cid:246)nen, Jaana Rajakko & Olavi Keski-Rahkonen
VTT Building and Transport
ISBN 951(cid:150)38(cid:150)6569(cid:150)X (URL: http://www.vtt.fi/inf/pdf/)
ISSN 1459(cid:150)7683 (URL: http://www.vtt.fi/inf/pdf/)
Copyright ' VTT 2005

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Technical editing Marja Kettunen
Published by
Series title, number and
report code of publication

VTT Working Papers
VTT(cid:150)WORK(cid:150)18

Author(s)
Nyyss(cid:246)nen, Teemu, Rajakko, Jaana & Keski-Rahkonen, Olavi
Title
On the reliability of fire detection and alarm systems
Exploration and analysis of data from nuclear and non-nuclear installations
Abstract
A literature review of reliability data of fire detection and alarm systems was made resulting
to rough estimates of some failure frequencies. No theoretical or technical articles on the
structure of reliability models of these installations were found. Inspection records of fire
detection and alarm system installations by SPEK were studied, and transferred in electronic
data base classifying observed failures in failure modes (59) and severity categories (3) guided
by freely written records in the original data. The results of that work are presented without
many comments in tabular form in this paper. A small sample of installations was collected,
and number of components in them was counted to derive some distributions for
determination of national populations of various components based on know total amount of
installations.
From NPPs (Loviisa, Olkiluoto and Barseb(cid:228)ck) failure reports were analysed, and observed
failures of fire detection and alarm systems were classified by severity and detection mode.
They are presented here in tabular form for the original and new addressable systems.
Populations were counted individually, but for all installations needed documents were not
available. Therefore, presented failure frequencies are just first estimates, which will be
refined later.

Keywords
fire detectors, fire alarm systems, failures
Activity unit
VTT Building and Transport, Kivimiehentie 4, P.O.Box 1803, FIN(cid:150)02044 VTT, Finland
ISBN Project number
951(cid:150)38(cid:150)6569(cid:150)X (URL: http://www.vtt.fi/inf/pdf/)
Date Language Pages
January 2005 English 62 p. + app. 6 p.
Name of project Commissioned by
Finnish Centre for Radiation and Nuclear Safety,
Ministry of Trade and Industry, Fortum
Engineering Ltd, Teollisuuden Voima Oy
Series title and ISSN Publisher
VTT Working Papers VTT Information Service
1459(cid:150)7683 (URL: http://www.vtt.fi/inf/pdf/) P.O. Box 2000, FIN(cid:150)02044 VTT, Finland
Phone internat. [phone]
Fax [phone]
Preface
This study was carried out as a part of the Fire Safety Research project (FISRE) which
is one of the projects in the Finnish Research Programme on Nuclear Power Plant
Safety (FINNUS).
The study has been financed by the Finnish Centre for Radiation and Nuclear Safety,
the Ministry of Trade and Industry, Fortum Engineering Ltd, and Teollisuuden Voima
Oy. Material and immaterial deliveries from SPEK, as well as information on buildings
and building fire protection devices by a considerable number of people made these
studies possible. We are indebted to Mr. Yasuaki Hagimoto, National Research Institute
of Police Science, Japan, for supplying Japanese reliability information articles.

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Contents
Preface...............................................................................................................................4
1. Introduction..................................................................................................................9
2. Fire detection and alarm systems...............................................................................11
2.1 Description of the systems................................................................................11
2.2 Reliability modelling of the systems................................................................13
2.3 Probability distributions...................................................................................18
2.4 Calculation of failure frequencies of fire detection and alarm systems and
system components...........................................................................................19
3. Literature survey on reliability of fire detection and alarm systems.........................21
3.1 Numerical values of failure rates and related properties of fire detection and
alarm systems...................................................................................................21
4. Population and physical size of fire alarm system installations................................27
4.1 Population of fire alarm system installations...................................................28
4.1.1 Protected floor area in sampled buildings with fire alarm...................28
4.1.2 Fire detector density.............................................................................29
4.1.3 Distribution of device circuits and detectors in non-nuclear
installations..........................................................................................30
4.1.4 Installation age distribution in the sample of buildings.......................32
4.2 Fire alarms systems in NPPs............................................................................33
4.2.1 Distribution of device circuits in NPPs................................................35
4.2.2 Distribution of cable length in NPPs....................................................35
5. Non-fire failure statistics............................................................................................37
5.1 Non-nuclear installations in Finland................................................................40
5.2 Non-fire failures in nuclear power plants.........................................................45
5.2.1 Number of failures by categories and plants........................................45
5.2.2 Details on critical failures....................................................................47
5.3 Inspection time interval distribution.................................................................51
6. Estimation of component failure rates.......................................................................52
6.1 Failures of fire alarm heads..............................................................................52
6.2 Failures of cabels..............................................................................................53
6.3 Failures of manual initiating devices................................................................54
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7. Discussion and conclusions.......................................................................................55
8. Summary....................................................................................................................57
References.......................................................................................................................58
Appendices
Appendix A: Detailed lists of system properties

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List of symbols
a Parameter in a distribution
A Floor area of a building or part of it [m2]
A Constant in equations containing floor area of a building or part of it [m2]
0
b Parameter in a distribution
BWR Boiling water reactor
c Normalisation coefficient in a distribution
f Frequency of fires [1/a]
FMEA Failure mode and effect analysis
FSAR Final Safety Analysis Report
F(x) Cumulative of a distribution of stochastic variable x
M Number of counts of an object within limited bounds
n Number of sprinkler heads, value of a discrete stochastic variable
N Number of demands, number of observations in a sample
NPP Nuclear power plant
p Probability value
P Probability function, potential loss
PWR Pressurized water reactor
SPEK Suomen pelastusalan keskusj(cid:228)rjest(cid:246) [Finnish Fire Protection Association]
SVK Suomen Vakuutusyhti(cid:246)iden Keskusliitto [Federation of Finnish Insurance
Companies]
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T Stochastic time variable
TUKES Turvatekniikan keskus [Finnish Safety Technology Authority]
UPS Uninterruptable power supply
X General stochastic variable
x Value of a general stochastic variable
x Parameter in Weibull or lognormal distribution
0
z Quantile of a cumulative distribution
α Parameter in Weibull or lognormal distribution
β Parameter in Weibull or lognormal distribution
λ Failure rate in a distribution, [1/a]
ν Number of degrees of freedom
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1. Introduction
In the Finnish nuclear research program FINNUS the general goal of fire project FISRE
was to develop fire risk analysis further towards full and quantitative living PSA. A
special emphasis was placed to improve calculation tools used to support PSA-analyses.
This goal was approached on three fronts: (a) experiments and modelling on hardware,
(b) software development and assessment, as well as (c) processing of statistical
information (Keski-Rahkonen 2000, 2002). Project FISRE was organised into three
subprojects the titles of which cover roughly the fronts mentioned above. The last of
them was ’active fire protection equipment’, which was further divided into two parts:
reliability of (1) fire detection and (2) sprinkler extinguishing systems. This task
concentrated on front (c). Laborious data mining and population counting of the task was
carried out in two master’s theses (Nyyss(cid:246)nen 2002, Rajakko 2002). This paper analyses
further the data obtained, and summarises the state of art of this project, which as a
scientific and technical problem needs further efforts.
A short history on the development of fire-PSA methods was given on the final report on
sprinklers in FISRE-project (R(cid:246)nty et al. 2004). Rather much of statements given there on
the general reliability modelling and statistical analyses of sprinkler installations apply as
well on fire detection and alarming systems.
Fire detection and alarming systems are considered effective means of automatic
information of potential fire spread in industrial buildings. Surprisingly, their
effectiveness in terms of reliability theory is not very well established in scientific
sense, since reliable data on the performance are very limited. The existing references
are either obsolete (Kingswell 1972, Sayers 1972, Watanabe 1979, Moliere 1982,
Krasner et al. 1985, Finucane & Pinkney 1989), of limited utility for a real system
design (T-Book 1992, OREDA 1992) or both (WASH-1400, 1975; McCormick 1981,
Green 1982).
Ramachandran showed indirectly the reliability of fire alarming systems by studying
statistically fire losses in different premises in UK (Ramachandran 1980, 1981a,b, 1992,
1993, Ramachandran & Chandler 1984). His recent monograph (Ramachandran 1998)
summarises these demonstrations on the value of fire detection and alarming systems.
Despite these economical assurances from system reliability point of view it is not
sufficient to know, that fire alarming system decreases fire losses. During the system
design phase quantitative analysis of system availability performance can be used to
identify and quantify both components dominating the risk and components with
marginal impact on system availability. Both of these foundations are potential targets
for system re-design. However, availability analysis of any technical system calls for
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component or at least sub-system level information about failure frequencies and down
times.
Ramachandran (1999) also presented a model of false alarm discrimination in a very
simple system. Bukowski et al. (1999) has presented a review of fire protection systems
but do not present much new data.
The purpose of the present study is to carry out a kind of failure mode and effect
analysis (FMEA) of detection and alarming systems starting from the component level
("the bottom-up approach") (Hłyland & Rausand 1994). The scope is preliminary data
analysis of these systems in Finnish nuclear power plants by studying relevant collected
maintenance reports from their whole lifetime. Since the studied population is very
small, probability to observe rare events from such material is still rather small, the
population of components was enlarged in two other directions: (i) a Swedish nuclear
power plant, and (ii) Finnish non-nuclear fire detection and alarming systems
installations, which might be different from nuclear applications, but as a much larger
population offer still a relevant reference.
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