Reviewed by: EP Peer Group Date: January 2013

Transcription

1 Page 1 of 7 Nuclear Generation Limited Company Specification Generic Emergency Handboo (Nuclear Energy Generation) Section 13 Emergency Engineering Originated by: Graham Woodcoc Emergency Planning Group Date: January 2013 Reviewed by: EP Peer Group Date: January 2013 Approved by: John Segg Head of Emergecny Planing Group Date: January 2013 Revision Amendment Impact level Date 003 Document converted to current EDF NG template Changes include company name and organisational updates. Docu incorporated in this issue Minor January Published in the United Kingdom by EDF Energy Nuclear Generation Ltd. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, including photocopying and recording, without the written permission of the copyright holder, EDF Energy Nuclear Generation Ltd, application for which should be addressed to the publisher. Such written permission must also be obtained before any part of this publication is stored in a retrieval system of any nature. Requests for copies of this document should be referred to Barnwood Document Centre, Location 12, EDF Energy Nuclear Generation Ltd, Barnett Way, Barnwood, Gloucester GL4 3RS (Tel: ). The electronic copy is the current issue and printing renders this document uncontrolled. Controlled copy-holders will continue to receive updates as usual. LIMITATION OF LIABILITY Whilst EDF Energy Nuclear Generation Ltd believes that the information given in this document is correct at the date of publication it does not guarantee that this is so, nor that the information is suitable for any particular purpose. Users must therefore satisfy themselves as to the suitability of the information for the purpose for which they require it and must mae all checs they deem necessary to verify the accuracy thereof. EDF Energy Nuclear Generation Ltd shall not be liable for any loss or damage (except for death or personal injury caused by negligence) arising from any use to which the information is put. Parent Document Ref: BEG/ICP/QUA/DM/003 Template Ref: BEG/FORM/QUA/002 Rev 023

2 Page 2 of 7 Contents 13.1 Sealing Of Breaches In Pressure Circuits Introduction Repair Classification Repair Techniques... 4 Table Table

3 Page 3 of Sealing Of Breaches In Pressure Circuits 1. Introduction Various techniques have been identified for sealing gas circuit breaches in an Emergency. The method chosen in any particular situation will depend on a number of factors such as size of breach, pressure, temperature and accessibility. This Emergency Procedure outlines the techniques available and the criteria for choosing a particular method. Detailed descriptions of the techniques and how to apply them are available in (Site Specific). The techniques outlined have been selected to cover a wide range of circumstances. However, it is not practical to cover all possible situations in detail. Some improvisation may be required, but the range of techniques outlined should provide, either individually or in combination, sufficient flexibility to enable any liely breach to be sealed. 2. Repair Classification The first criteria affecting the choice of the most appropriate sealing technique is the size of the breach. For the purpose of this procedure sizes are divided into three groups: A. Small up to 100mm diameter (small bore pipes, etc) or equivalent B. Medium mm (Larger pipes/valves) C. Large Over 500mm (manholes, standpipes, gas ducts, etc) Appendix A gives a list of pipes, penetrations, etc in the gas circuit that may potentially require repair in an emergency. The Appendix lists size, shape, location and material. (Example attached). The level of repair required is the other main criteria used for deciding the method. This is also divided into three groups. 1. First-Aid measures. 2. Robust Repairs. 3. Engineered Closures. Although the three repair levels are shown as discrete criteria, in practice more than one of them may be required in some situations, e.g. it may be necessary to carry out a quic temporary repair to maintain reactor cooling while preparations are made for a more permanent seal, or to stop/reduce the lea to enable a more robust repair method to be applied successfully. Where this is necessary, care should be taen that the first aid measures used do not prevent the follow up repair being carried out. The two groups of three criteria above are combined to give a total of nine repair classifications for choosing the most appropriate techniques.

4 Page 4 of 7 3. Repair Techniques The repair methods can be broadly divided into three basic types, blocing, patching and encapsulation. Table 1 lists the potentially useful repair methods under these three categories. Those that are most liely to be of use in an emergency at this site are indicated as core techniques. Within these basic types are most appropriate techniques for any repair will depend on the lea classifications above and the particular conditions and circumstances encountered. Table 2 cross references the lea classifications to the most appropriate potential repair techniques from Table 1. Equipment and material necessary for implementing the core techniques is held in special storage located at (Site Specific). A complete list of the necessary equipment and materials for each technique is ept at the storage point. (Examples are attached). This equipment and material will be checed on a regular basis, and a schedule or replacement implemented for items with a limited storage life. Appendix B details where materials, equipment and specialist services can be obtained for the non-core techniques listed in Table 1. (Examples are attached). Where necessary, site staff deployed in damage control and repair will have been trained in implementing the core techniques. A general tool and material it is also ept at (Site Specific) for use in an emergency. A list of contents is ept with the it. (An example is attached).

5 Page 5 of 7 Table 1 SUMMARY OF POTENTIAL TECHNIQUES FOR EMERGENCY REPAIR OF A PRESSURE CIRCUIT BREACH IN TERMS OF FUNCTION Blocing Methods: (a) Pipe-crimping for pipes up to 100mm diameter with or without injection of sealant. Special equipment required. No temperature or pressure limit. Excellent first aid measure for temporary (as-crimped) or more permanent (with sealant) lea sealing. (b) (c) (d) (e) (f) (g) (h) (i) (j) Pipe bungs mechanically expanded (e.g. Wedge-Loc ). Probably limited to smaller sizes (<150mm). Temperature limit 120 C, but capable of sealing full reactor pressure. Tapered mild steel plugs (capable of subsequent welding). No temperature or pressure limit once fitted. Valves for compression joint fixing or welded attachment, probably in conjunction with pipecrimping. Quic setting sprayed concrete with steel mesh support and expand metal bac sheet, with or without thermal insulation barrier. Low to ambient pressures; robust repair of large breaches. Inflatable devices for internal use. Low pressure and temperature applications only. Inflatable devices baced up with quic setting concrete for higher pressures and temperatures. Welded closures for ad hoc repair. No temperature limit; some pressure containment possible. Pre-engineered items: standpipe closures, blaning plates. No temperature restriction, some pressure containment. Bul concrete pumping using a contractor s supply vehicle and equipment. Moderate temperatures; some pressure containment. Patching Methods () (l) Resin plus glass or ceramic fibre bandages, either two-part epoxy (e.g. Thistlebond, Belzona, Araldite) for moderate temperatures (<150 C) or air-hardening silicate cements for higher temperatures. Suitable for small and medium sized breaches. Regarded as a first-aid measure only for low pressure applications unless baced up with sheet metal. Woven fabric (e.g. tarpaulin, ceramic or glass fibre) in conjunction with a wire mesh support and secured with wire rope. A non-combustible material is preferred, e.g. aluminised fire blanet. For retention of air-borne particles only.

6 Page 6 of 7 (m) Split sheet metal sleeves with elastomeric sealing gaset (e.g. neoprene or viton, but silicone rubber preferred) secured with steel bands. Application restricted to less than 300 C and to moderate pressures. Can be locally prepared to deal with splits in pipes (no diameter limit) and more complex shapes in conjunction with resin bandage over-wrapping. Encapsulation Methods: (n) (o) (p) (q) High pressure joint sealing (e.g. as offered on a contractual basis by Furmanite Engineering Ltd). Flange and lea-site encapsulation, e.g. Team In. Self-seal Line Repair Enclosures. Special engineering closures for specific purposes, e.g. top-hat closure for failed manhole cover, total enclosure of craced bellows unit. Fire-resistant sandbags. Possible applications include temporary blocing of a burst duct prior to more robust repair, e.g. method e, for temporary sealing of the biological shield, as a temporary standpipe cover in conjunction with a steel cover-plate, and for fire containment. NOTE: Core techniques indicated by Core prefix to reference letter. T (See Table below for guidance on choosing appropriate core techniques for a particular site). GUIDANCE ON SELECTION OF EMERGENCY REPAIR TECHNIQUES ACCORDING TO POTENTIAL USEFULNESS GROUP POTENTIAL USEFULNESS METHOD (TABLE 1) E Essential Methods Core Techniques (Generally applicable) S Supplementary Methods f g h l q O Optional Methods (For special cases only) a c m b d i j n o p APPLICATION (TABLE 2) Ala A2c Bl, Cl Clm, Blm Blf, Clf B2g, C2g A2h, B2h A1, B1 C11, B11 C1q A1b A3d B3i C2j A2n B3o C3p

7 Page 7 of 7 Table 2 CLASSIFICATION OF POTENTIAL EMERGENCY REPAIR METHODS IN TERMS OF APPLICATION LEVEL OF RESPONSE A SMALL HOLES AND LEAKS (up to 100mm) dia equiv.) B MEDIUM BREACHES ( mm dia equiv.) C LARGE BREACHES (<500mm dia equiv.) 1 FIRST AID MEASURES a b f q f l q 2 ROBUST REPAIRS a* m c n h e g h m p See Table 1 for Key to Repair Techniques ** with injection of sealant