Cost/benefit analyses of reactor safety systems

European Commission Directorate-General For The Information Society And Media Directorate-General For Research And Innovation

Description

Nuclear energy and safety

Informations

• Publié par: EUROPEAN-COMMISSION-DIRECTORATE-GENERAL-FOR-THE-INFORMATION-SOCIETY-AND-MEDIA-DI
• Nombre de lectures: 10
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

euH a- ¿ yf
Commission of the European Communities
nuclear science
and technology
Cost/benefit analyses of
reactor safety systems ^
Commission of the European Communities
Cost/benefit analyses of
reactor safety systems
Lahmeyer International GmbH
D-6000 Frankfurt/Main 71
ECI-701-80-9-D
Contract Nos
ECI-1240-B7221-84-D
Final report
PARI [UV\ p'Mioih.
Directorate-General
Science, Research and Development
M.C 'c. .
1988 t~EÜFM1699EN
CL Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Di rectorate-General
Telecommunications, Information Industries and Innovation
Bâtiment Jean Monnet
LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the,European Communities nor any person acting
on behalf of then is responsible for the use which might be made of
the following information
Cataloguing data can be found at the end of this publication
Luxembourg: Office for Official Publications of the European Communities, 1988
ISBN 92-825-8935-8 Catalogue number: CD-NA-11699-EN-C
© ECSC-EEC-EAEC, Brussels • Luxembourg, 1988
Printed in Belgium CONTENTS
Page
1. Summary and outlook 1
2. Introduction 4
3. The containment system of a nuclear power plant
with a pressurized water reactor 6
3.1 Containment structure 8
3.2 Leakoff system
3.3 Annulus exhaust-air handling system 9
3.4 Containment spray system 12
4. Description of the emergency cooling and residual
heat removal system4
5. Core meltdown in a nuclear power station with a
pressurized water reactor 20
6. Activity release program6
6.1 Outline of the activity release program 2
6.2 Deposition of fission products released during a
loss-of-coolant accident9
6.3 Description of the leakoff system, the annulus
exhaust-air handling system and the containment
spray system in the activity release program 30
6.4 Time scales used for the various incidents2
6.5 Detailed description of the activity release
program 35
6.6 Summary of input data for the activity release
program 40 Page
7. Calculation of dilution air volumes for the
as-designed containment system 43
7.1 Event sequence diagram
7.2 Assessment of the non-availability of containment
system sub-systems 46
7.3 Dilution air volumes7
8. Calculation of the benefit of the containment
system sub-systems 51
8.1n of the benefit of the containment
structure2
8.2 Calculation of the benefit of the leakoff
system4
8.3 Calculation of the benefit of the annulus
exhaust-air handling system 55
8.4 Calculation of the benefit of the containment
spray system 56
9. Calculation of the benefit of and the cost/benefit
ratio for the as-designed state 58
10. Calculation of the benefit of the containment
system sub-systems with variations in leakoff
system performance 60
11. Calculation of the benefit of the containment
system sub-systems with variations in the
performance of the annulus exhaust-air handling
system 63
12. Calculation of the benefit of the containment
system sub-systems with variations in the wash-out
constants of the spray system 66
13. Calculation of the benefit of the containment
system sub-systems with variation of sub-system
non-availabilities 69
IV Page
14. Discussion on the calculation of the benefit
of the containment structure, leakoff system,
annulus exhaust-air handling system and
containment spray system 73
14.1 Benefit of the containment structure
14.2t of the leakoff system4
14.2.1 Benefit of thef system with
variations in recirculation capacity 75
14.2.2 Benefit of the leakoff system with
variations in the level of filter efficiency
in the annulus exhaust-air handling system 75
14.2.3 Benefit of the leakoff system with
variation of the spray system wash-out
constants 76
14.3 Benefit of the annulus exhaust-air handling
system7
14.3.1 Benefit of the annulus exhaust-air handling
system with variation of leakoff system
recirculation capacity
14.3.2 Benefit of the annulus exhaust-air handling
system with variation of the filter
efficiency level 7
14.3.3 Benefit of the annulus exhaust-air handling
system with variation in spray system
wash-out8
14.4 Benefit of the spray system 7
14.4.1t of the spray system with variation of
leakoff system recirculation capacity
14.4.2 Benefit of the spray system with variation in
the level of filter efficiency of the annulus
exhaust-air handling system 79
- V -Page
14.4.3 Benefit of the spray system as a function of
the wash-out constants for iodine and aerosols 79
14.5 Benefit of the containment systems as a
function of variations in NV , NV, and NV 80
15. Determination of the cost/benefit ratios for
the containment system sub-systems as a
function of sub-system variations 81
15.1 Exponential costing of the varied leakoff
system 8
15.2 Costing basis No 2 for the varied leakoff
system6
15.3 Linear costing of the varied leakoff system
(costing basis No 3)8
15.4 Cost/benefit ratio for the varied annulus
exhaust-air handling system 91
15.5t ratio for the varied spray system 93
16. Discussion on the cost/benefit ratios for the
containment system sub-systems5
17. References 102
18. Annexes:
- Dilution air volumes calculated on the basis
of the variations in the containment system
sub-systems 104-117
- Printout from the activity release program 118-120
- VI -1. SUMMARY AND OUTLOOK
This study presents a methodology for quantitative assessment of the
benefit yielded by the various sub-systems of a nuclear reactor
containment system. The benefit is derived from an estimate of the
damage from which the environment is protected by the existence of the
sub-systems, account being taken of the probabilities of occurrence of
malfunctions and accidents. Damage to the plant itself is not covered
in this approach.
The methodology can also be used to determine the cost/benefit ratios
of the individual sub-systems in order to reveal the mean benefit
obtained from one Deutsche Mark invested in them.
For demonstration purposes, the methodology was applied to a 1300-MWe
KWU nuclear power station with a pressurized-water reactor. The
accident sequence considered was that of a major loss-of-coolant t with subsequent core meltdown, as investigated in detail in
the German Risk Study.
To facilitate comparison of the benefits derived from the various
safety features, the damage criterion chosen is the quantity of air
required to dilute a given quantity of released nuclides to permissi­
ble considerations in accordance with the radiation protection regula­
tion (Strahlenschutzverordnung). The quantities of dilution air were
calculated by means of a computer program for various categories of
loss-of-coolant accident.
Once the benefits and costs of the containment sub-systems have been
determined, a cost/benefit comparison is carried out. The benefit per
DM invested is a few hundred times greater in the case of the contain­
ment than in that of the leakoff system or the annulus exhaust-air
handling system. The cost/benefit ratio of the spray system is about
one order of magnitude less than that of the containment.
After the benefits and cost/benefit ratios had been determined for the
as-designed power plant, the performance characteristics of three
sub-systems, the leakoff system, annulus exhaust air handling system
1 -and spray system, were varied. For this purpose, the parameters which
describe these systems in the activity release program were altered.
The costs were simultaneously altered in order to take account of the
performance variations.
The effects of varying the performance of the individual sub-systems
on their benefit ard cost-benefit and also en the benefit of other
sub-systems are discussed and optimization methods are outlined.
The simple model used in this study and the fact that the approach is
restricted to the accident sequences stated do not allow immediate
conclusions to be drawn from the results with regard to future systems
design. A procedure such as that outlined below would be required for
that purpose.
1. A representative spectrum of malfunction and accident sequences
which cause the systems under consideration to respond must be
devised.
2. The sequences selected must be simulated by means of a realistic
model, so that the benefit of the systems can be derived
realistically from the activity release.
3. The investment cost of the systems or of the system variations in
question must be estimated as accurately as possible so that valid
conclusions can be drawn from the cost-benefit ratios and their
interrelationship.
Since the benefit of one sub-system generally depends on the other
existing sub-systems, the procedure described can be used to determine
the benefit to be expected from any additional sub-system that might
be installed or from modification of a sub-system.
Answers to questions concerning the optimum use of resources for the
various sub-systems