Reliability of sub-seabed disposal operations for high level waste

Directorate-General For Translation European Commission

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Research policy and organisation
Environment policy and protection of the environment

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• Publié par: EUROPEAN-COMMISSION
• Nombre de lectures: 1
• Langue: English
• Poids de l'ouvrage: 3 Mo

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Reliability of Sub-Seabed
Disposal Operations (
for High Level Waste
M. M. Sarshar
Published byGRAHAM &TROTMAN Ltd
for the Commission of the European Communities THE COMMISSION OF THE EUROPEAN COMMUNITIES
RELIABILITY OF SUB-SEABED
DISPOSAL OPERATIONS
FOR HIGH LEVEL WASTE This report was prepared for the European Atomic Energy Community's Cost-
sharing Research Programme on "Radioactive Waste Management and Disposal'
Under contract No 395-83-7 WAS UK
Project 7B: "Disposal in Sea-bed Geological Formations". RELIABILITY OF SUB-SEABED
DISPOSAL OPERATIONS
FOR HIGH LEVEL WASTE
by
M. M. SARSHAR
Taylor Woodrow Construction Limited
Southall, Middlesex, UK
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Published by GRAHAM & TROTMATTLTcf
for the Commission of the European Communities Published ¡η 1986 by Graham & Trotman Ltd
66 Wilton Road, London SW1V 1DE, UK
for the Commission of the European Communities,
Directorate-General Information Market and Innovation,
Luxembourg
EUR 10542
c ECSC, EEC, EAEC, Brussels and Luxembourg, 1986.
ISBN 0 86010 835 χ
LCCCN and British Library CIP data available from publisher.
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Printed and bound in Great Britain
iv CONTENTS
SUMMARY
1. INTRODUCTION 1
2. OBJECTIVES
3. METHOD OF APPROACH 2
RELIABILITY ASSESSMENT OF DRILLED EMPLACEMENT METHOD 3
4. SUMMARY OF OPERATIONS 3
4.1 Description of Drilled Emplacement Method
4.2 General Parameters 4
5. REFERENCE CRITERIA — KEY ASSUMPTIONS 5
6. FAILURE MODE, EFFECTS AND CRITICALITY ANALYSIS (FMECA) 7
6.1 Definition 7
6.2 Description of Analysis
6.3 Summary of Results 11
6.4 Assessment of Results
7. FAULT TREE ANALYSIS (FTA)2
7.1 Definition
7.2 Description of FTA tasks
7.3 Sub-Contract Work4
7.4 Assessment of Probability Values 15
7.5 Summary of Results6
7.6 Effect of Redundancy in the Lowering System7
7.7t of FTA Results8
8. FAULT TREE ANALYSIS (FTA) Hazard to Personnel9
8.1 Definition 1
8.2 Description of FTA
8.3 Summary of Results
8.4 Assessment of Results 20
8.5 Historical Review of Radiation Facilities 22
9. RELIABILITY ASSESSMENT OF PENETRATOR METHOD4
9.1 Summary of Operation
9.2 General Parameters
10. REFERENCE CRITERIA (PENETRATOR METHOD) 25
11. FAULT TREE ANALYSIS (FTA) (PENETRATOR METHOD)6
11.1 General 2
11.2 FTA —Release of Radioactivity to the Environment
11.3 Sensitivity Analysis7
11.4 Summary of Results12. DECISION ANALYSIS/ACCEPTANCE CRITERIA 29
12.1 General 29
12.2 Loss of life 29
12.3 Release of Radioactivity to Environment 30
12.4 Acceptance Criteria 33
12.5 Criteria for Comparison of Disposal Methods 37
13. COMPARISON OF DRILLED EMPLACEMENT AND PENETRATOR
METHODS 38
14. CONCLUSIONS 39
15. LIST OF REFERENCES 41
LIST OF TABLES
TABLE 1 SUMMARY OF FAULT TREE ANALYSIS (FTA)
DRILLED EMPLACEMENT METHOD 43
TABLE 2 FTA SENSITIVITY ANALYSIS
DRILLEDT METHOD 43
TABLE 3 SUMMARY OF FAULT TREE ANALYSIS (FTA)
PENETRATOR METHOD 43
LIST OF FIGURES
FIG. 1 Disposal Operation
44 Drilled Emplacement Method
FIG. 2l Operation Options
44 Penetrator Method
45 FIG. 3 Penetrator — Reference Design
45 FIG. 4 Disposal Ship — Option E
FIG. 5 Graph of Decay of Total
46 Radioactivity over a Long Period
FIG. 6 Summary of Results of Preliminary
47 Pre-emplacement Safety Analysis
FIG. 7 Process of Dispersion of Radionuclides
48 in Ocean
VI 48 FIG. 8 Seabed Disposal Study Sites
49 FIG. 9 Ocean Disposal, Barriers to Man
50 FIG. 10 Effects of Radiation
51 FIG. 11 Estimate of Maximum Dose Uptake from Ship Sinking
FIG. C-1 Fault Tree — Release of Radioactivity to Environment
132 Drilled Emplacement Method (Appendix C)
FIG. D-1 Fault Tree — Hazard to Personnel
156
Drilled Emplacement Method (Appendix D)
FIG. E-1 Fault Tree — Release of Radioactivity to Environment
176
Penetrator Method (Appendix E)
LIST OF APPENDIXES
APPENDIX A Extracts from FMECA, Drilled Emplacement Method 52 X Β FAULT TREE ANALYSIS 74
• DrilledEmplacementMethod
• SystemsReliabilityService (SRS) explanatory notes and FTA
Results
• FaultTreeFigures
APPENDIX C FAULT TREEANALYSIS
RELEASE OFRADIOACTIVITY TO THE ENVIRONMENT 110
• Drilled Emplacement Method
• Computer Output — T.W. Program CUTS
• Fault Tree (Figure C-1)
APPENDIX D FAULT TREE ANALYSIS 134
HAZARDTOPERSONNEL
• DrilledEmplacementMethod
• FTAExplanatoryNotes
• FTA ComputerOutput
• Fault Tree(FigureD-1)
• Table D-1, D-2,Statistical Data
APPENDIXE FAULT TREE ANALYSIS157
PENETRATOR METHOD
• Explanatory Notes — Derivation of Failure Rates
Computer Output
• Fault Tree (Figure E-1)
VII SUMMARY
This report gives a summary of the reliability study related to the
disposal of high level waste in deep ocean sediments. Two methods of
disposal, by drilled emplacement and by penetrator as developed by
Taylor Woodrow and Ove Arup & Partners respectively, have been
assessed in this study.
For assessment of the reliability, two well established methods have
been used. These are:
a) Failure mode effects and criticality analysis (FMECA)
b) Fault tree analysis (FTA).
For the fault tree analysis, two major undesired events have been
considered. The events are:
i) Loss of lives of personnel involved in the operation
ii) Release of radioactivity to the environment.
The fault tree analysis has shown that loss of lives of personnel resulting
from accidental exposure to radiation is insignificant.
For the events leading to the release of radioactivity to the environment,
fault tree analysis has shown that the probability values for such events
occurring are in the order of 4 χ "IO"2 to 1 χ "IO"2 per year for drilled
emplacement and the penetrator method respectively.
When the number of canisters involved in each event are considered,
the drilled emplacement process would result in the loss or
misplacement of 2.7 canisters per year on average, while the figure for
the penetrator process is 0.2 canisters per year.
The comparisons between the two methods of disposal shows that the
penetrator method is in general a safer operation, ignoring any post
emplacement differences. The addition of redundant lowering systems
to the drilled emplacement process could have the effect of halving the
failure rates given above.
ACKNOWLEDGEMENT
Contributions have been made to the technical
contents of this report by the following
members of Taylor Woodrow staff:
Mr. I. Barody
Mr. M. R. C. Bury
Dr. C. Fleischer
Contributions from outside consultants
are acknowledged in Section 7.3.
viii