1、 IEEE Standard Criteria for the Design, Installation, and Qualification of Raceway Systems for Class 1E Circuits for Nuclear Power Generating Stations Sponsored by the Nuclear Power Engineering Committee IEEE 3 Park Avenue New York, NY 10016-5997 USA 24 February 2012 IEEE Power +1 978 750 8400. Perm
2、ission to photocopy portions of any individual standard for educational classroom use can also be obtained through the Copyright Clearance Center. Copyright 2012 IEEE. All rights reserved. ivIntroduction This introduction is not part of IEEE Std 628-2011, IEEE Standard Criteria for the Design, Insta
3、llation, and Qualification of Raceway Systems for Class 1E Circuits for Nuclear Power Generating Stations. The original document was issued in 1987 and reaffirmed in 1992. During the process of reaffirmation, it was agreed to add earthquake experience data as an acceptable method of performing seism
4、ic qualification for raceway systems in the next revision of the standard. Therefore, the 2001 revision of this standard incorporated methods developed by the Seismic Qualification Users Group (SQUG). Annex B was added to the document to assist the user with the new methodology. The applicability of
5、 this methodology is contingent on its acceptability per the plant licensing basis. It should be noted, however, that the SQUG methodology was approved by the U.S. Nuclear Regulatory Commission (NRC) for verification of seismic adequacy of the cable tray systems at older nuclear power plants that we
6、re licensed prior to IEEE Std 344TM-1975 B5.aOther changes made to the standard were format changes and upgrading of the document references. The definitions contained in the original and reaffirmed documents were removed as they are now contained in The IEEE Standards Dictionary: Glossary of Terms
7、however, they shall be designed to seismic Category 1 requirements to prevent failure during a seismic event. Documentation requirements for the raceway system shall be in accordance with Clause 7 of this standard. The raceway system shall be designed to perform its functions and shall not degrade t
8、he safety functions of adjacent safety-related systems during and after experiencing all conditions postulated to occur in its environment. As a minimum, the design shall adhere to the basic requirements of this standard and of IEEE Std 384-2008.12Clearances with respect to other systems shall be es
9、tablished and provided to ensure that movement due to loads and load combinations (4.10.1) will not affect the integrity of the raceway system. Relative displacement of the raceway system to other systems, equipment, or structures shall be considered in the design of raceway systems. The raceway sup
10、ports shall be designed to accommodate differential settlement and deflections between structures. 4.1.3 Layout Raceways shall not be located close to heat sources unless cables are selected or derated for the highest expected ambient temperature. Longitudinal expansion of raceways shall be consider
11、ed in areas with varying temperatures. The design of raceways shall accommodate the installation of qualified fire stops where raceways penetrate a fire barrier. For additional fire considerations, see IEEE Std 690-2004. 11Notes in text, tables, and figures of a standard are given for information on
12、ly and do not contain requirements needed to implement this standard. 12Information on references can be found in Clause 2. IEEE Std 628-2011 IEEE Standard Criteria for the Design, Installation, and Qualification of Raceway Systems for Class 1E Circuits for Nuclear Power Generating Stations Copyrigh
13、t 2012 IEEE. All rights reserved. 54.2 Separation criteria 4.2.1 Design requirements The design requirements for physical independence and separation of raceways containing Class 1E circuits are contained in IEEE Std 384-2008. 4.2.2 Raceways Raceways shall be separated according to the voltage class
14、ification of the cables contained within them; see IEEE Std 690-2004. 4.3 Grounding Metallic raceways shall be electrically continuous and electrically connected to the station ground grid in accordance with IEEE Std 665-1995. 4.4 Raceway identification Raceways shall be marked in accordance with th
15、e requirements of IEEE Std 384-2008; embedded conduit shall be marked at all access points. 4.5 Raceway system protection Raceway systems in hazardous areas shall be designed in accordance with IEEE Std 384-2008. 4.6 Environmental considerations The selection of materials used for raceway systems an
16、d the finishes required shall be based on the environmental conditions expected where the raceway systems are installed. To meet the requirements for combustible gas control, materials for raceway systems to be installed in containment shall be selected with due consideration to minimizing the gener
17、ation of hydrogen gas following a design basis event (Regulatory Guide 1.7 B7).13For additional guidelines pertaining to environmental considerations for raceway systems; see Annex B. 4.7 Materials The physical properties of materials used for raceway systems shall meet or exceed the minimum require
18、ments established for the design and qualification of these systems. Conduits shall meet the minimum requirements in 4.7.1 and 4.7.2; cable trays shall meet the minimum requirements of 4.7.3. 13The numbers in brackets correspond to the bibliography in Annex A. IEEE Std 628-2011 IEEE Standard Criteri
19、a for the Design, Installation, and Qualification of Raceway Systems for Class 1E Circuits for Nuclear Power Generating Stations Copyright 2012 IEEE. All rights reserved. 64.7.1 Metallic conduit 4.7.1.1 Rigid steel conduit (RSC) RSC shall meet the requirements of ANSI C80.1-2005 and UL 6-2007. 4.7.1
20、.2 Rigid aluminum conduit (RAC) RAC shall meet the requirements of ANSI C80.5-2005. 4.7.1.3 Intermediate metal conduit (IMC) IMC shall meet the requirements of ANSI C80.6-2005 and UL 1242-2006. 4.7.1.4 Electrical metallic tubing (EMT) EMT shall meet the requirements of ANSI C80.3-2005 and UL 797-200
21、7. 4.7.1.5 Flexible metal conduit Flexible metal conduit shall meet the requirements of UL 1-2005. 4.7.1.6 Fittings and accessories Conduit fittings and accessories shall meet the requirements of NEMA FB 1-2007, UL 514A-2004, UL 514B-2004, and UL 514C-2008. 4.7.2 Nonmetallic conduit 4.7.2.1 Polyviny
22、l chloride (PVC) conduit PVC conduit fittings shall meet the requirements of NEMA TC 3-2004 and NEMA TC 9-2004. 4.7.2.2 Polyethylene (PE) conduit PE conduit shall meet the requirements of NEMA TC 2-2003. 4.7.2.3 Acrylonitrile butadiene styrene (ABS) conduit ABS conduit shall meet the requirements of
23、 NEMA TC 6 see IEEE Std 690-2004. 4.9.1.2 Sizing Conduit shall be sized to avoid critical jamming ratio diameters; see IEEE Std 690-2004. 4.9.1.3 Seismic loading Unless justification is otherwise provided, rigid metal conduit (RMC) or IMC shall be used in exposed conduit systems designed for seismic
24、 loading. 4.9.1.4 Compliance Where compliance is required by local, state, or federal laws, the National Electrical Code(NEC) (NFPA 70) shall be used in selecting conduit types for use in hazardous locations. 4.9.1.5 Flexible metal conduit The length and installed configuration of flexible metal con
25、duit shall be designed to provide for dynamic and thermal movement and to accommodate the largest minimum bending radius of the cables to be installed. The length of flexible metal conduit shall be accounted for in the design and qualification of the conduit system. Flexible entry shall be used for
26、conduit entering Class 1E equipment where relative movement between the conduit and the equipment is anticipated. 4.9.1.6 Welding of conduits Welding of conduits shall not be permitted. 4.9.1.7 Metallic conduit system The entire metallic conduit system, whether embedded or exposed, shall be electric
27、ally continuous and grounded in accordance with IEEE Std 665-1995. Where used as the equipment grounding conductor, flexible conduit and associated fittings shall be suitable for the anticipated ground fault current, or they shall be paralleled with a ground cable of suitable size. IEEE Std 628-2011
28、 IEEE Standard Criteria for the Design, Installation, and Qualification of Raceway Systems for Class 1E Circuits for Nuclear Power Generating Stations Copyright 2012 IEEE. All rights reserved. 94.9.1.8 Embedded conduit Embedded conduit may be either metallic or nonmetallic. When embedded in building
29、 walls or floors, it shall meet the requirements of ACI 349/349R-2006, unless justification is otherwise provided. Embedded conduit subject to flooding shall slope either to boxes, handholes, or manholes for drainage or be sealed to exclude the entry of water. Where embedded conduit crosses a seismi
30、c, vibration, or expansion/contraction joint, a piece of flexible conduit or suitable fitting shall be installed to allow relative movement of the structures without damaging the conduit. 4.9.1.9 Embedded conduit protection Protection shall be provided for embedded conduit at floor levels and other
31、locations where physical damage to cables is likely. 4.9.2 Cable tray system requirements 4.9.2.1 Cable tray design Cable trays shall be designed to carry their design dead load (DL) (see 4.10.1.1.1) and a minimum concentrated load of 90.7 kg (200 lb) at midspan at the centerline of the tray or on e
32、ither side rail. Under this condition, the tray shall neither fail nor be permanently distorted. 4.9.2.2 Cable tray protection Protection shall be provided on exposed vertical tray risers at floor levels and other locations where physical damage to cables is likely. 4.9.2.3 Cable tray utilization Ca
33、ble trays shall not be utilized to carry ducts, piping, instrument tubing, or other equipment unless it can be demonstrated that the Class 1E functions of the cables will not be degraded below an acceptable level. 4.9.2.4 Grounding Cable tray systems shall be electrically continuous and solidly grou
34、nded. Where the tray is not capable of serving as an adequate ground return path, a ground conductor of suitable size shall be attached to and run parallel with the tray. 4.9.2.5 Flexible connectors Unless accounted for in the design, conduits shall not be connected to trays. Where continuity of met
35、allic shielding or protection of conductors is required, a flexible connection shall be used to accommodate the horizontal and vertical movement caused by a dynamic load. IEEE Std 628-2011 IEEE Standard Criteria for the Design, Installation, and Qualification of Raceway Systems for Class 1E Circuits
36、 for Nuclear Power Generating Stations Copyright 2012 IEEE. All rights reserved. 104.9.3 Wireway system requirements 4.9.3.1 Extent of permission Wireways shall be permitted only for exposed work. Wireways shall not be installed in any hazardous location or where subjected to severe physical damage
37、or corrosive vapor. 4.9.3.2 Supports Wireways shall be securely attached to the supports. Adjoining wireway sections shall be securely fastened together to provide a rigid joint. Vertical runs shall have no more than one joint between supports. 4.9.3.3 Pass-through Wireways shall be permitted to pas
38、s through walls and floors if the pass-through is in unbroken lengths. 4.9.3.4 Extension Extension from wireways shall be made with rigid or flexible metal conduit, intermediate metal conduit, or trays, where compliance with the NEC is required by local, state, or federal laws. All dead loads acting
39、 on wireways shall be included in the analysis. 4.9.3.5 Grounding Wireways shall be electrically continuous and solidly grounded. Where the wireway is not capable of serving as an adequate ground return path, a ground conductor of suitable size shall be attached to and run parallel with the wireway.
40、 4.9.4 Underground duct system requirements 4.9.4.1 Duct banks Duct banks entering buildings, manholes, or handholes shall allow for relative displacement between the structure and the duct bank. 4.9.4.2 Duct bank protection Protection shall be provided on exposed duct banks at floor levels and othe
41、r locations where physical damage to cables is likely. 4.9.4.3 Drainage The duct bank shall be sloped to drainage points, manholes, or handholes. All encased duct joints shall be concrete-tight. Manholes for duct bank access shall have accommodations for temporary sump pumps for water draining. Manh
42、oles located below the ground water line shall have a permanent sump pump design. IEEE Std 628-2011 IEEE Standard Criteria for the Design, Installation, and Qualification of Raceway Systems for Class 1E Circuits for Nuclear Power Generating Stations Copyright 2012 IEEE. All rights reserved. 114.9.4.
43、4 Duct length and configuration The duct bank length and configuration between pull points (such as manholes or handholes) shall not cause cable side-wall pressures, cable bending radii, and cable pulling tensions that exceed specified requirements (see IEEE Std 690-2004). Cable pull points shall ha
44、ve openings sufficiently sized to accommodate the cables minimum bending radius during installation. 4.9.4.5 Duct spacing The spacing of ducts shall be based on thermal considerations (such as cable I2R losses or circulating currents) and shall ensure adequate concrete encasement. Duct spacer materi
45、als shall be compatible with the duct material. The duct spacer type and longitudinal spacing shall be chosen to prevent excessive deflection, shall not deform the duct wall, and shall be staggered to avoid shear planes. The bottom spacer shall provide sufficient clearance from the trench floor to p
46、ermit the specified concrete layer thickness. Wood shall not be used for duct spacers. 4.9.4.6 Metallic ducts Metallic ducts shall be electrically continuous throughout and grounded at each access point. 4.9.4.7 Ground wire A ground wire of suitable size shall be run along with nonmetallic duct bank
47、s. It shall enter every manhole and handhole. The ground wire shall be connected to the station ground system at each end of the duct banks. 4.9.4.8 Damage To avoid damage from the circulating currents, nonmetallic ducts in a bank shall not be looped by ferrous materials (such as rebar or iron mesh)
48、 unless the ferrous materials are far enough away to minimize inductive heating. 4.9.4.9 Underground raceway identification Underground raceways shall be marked with the duct identification and safety division designations at each access point. Duct banks external to structures shall be marked with
49、surface and subsurface location markings. 4.9.4.10 Duct bank encasement The duct bank encasement shall consist of materials such as sand or reinforced concrete, depending on the seismic conditions at the site. 4.9.4.11 Reinforced concrete encasement Duct banks, manholes, and handholes encased in reinforced concrete shall have concrete adequately reinforced so they will be able to withstand the design loads and remain functional. IEEE Std 628-2011 IEEE Standard Criteria for the Design, Installation, and Qualification of Raceway Systems for Class 1E Circuits for Nuclear Power
