ML20134K663
| ML20134K663 | |
| Person / Time | |
|---|---|
| Issue date: | 07/24/1985 |
| From: | Campbell W NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | |
| Shared Package | |
| ML19310G650 | List: |
| References | |
| TASK-MS-203-4, TASK-RE REGGD-01.082, REGGD-1.082, NUDOCS 8508300343 | |
| Download: ML20134K663 (32) | |
Text
{{#Wiki_filter:_ . . ~ - . . - - - .: - .. . . 1 DRAFT 3 2 Division 1
'l 3 Task MS 203-4 f July 24,1985
- 1 4
Contact:
W. E. Campbell, Jr. (301) 443-7856, MS 212 NL 5 PROPOSED REVISION 1 TO REGULATORY GUIDE 1.82 6 WATER SOURCES 7 [ SUMPS] FOR [EMERGENEY-60RE-600tfN6 8 ANB-EONTAINMENT-SPRAY-SYSTEMS] 9 LONG TERM RECIRCULATION 10 COOLING FOLLOWING A LOSS OF 11 COOLANT ACCIDENT 1 12 A. INTRODUCTION 13 General Design Criteria 35, " Emergency Core Cooling," 36, " Inspection - 14 of Emergency Core Cooling System," 37, " Testing of Emergency Core Cooling 15 System," 38, " Containment Heat Removal," 39, " Inspection of Containment Heat 16 Removal System," and 40, " Testing of Containment Heat Removal System," of 17 Appendix A, " General Design Criteria for Nuclear Power Plants," to 10 CFR 18 Part 50, " Domestic Licensing of Production and Utilization Facilities," require 19 that [a] systems be provided to [ remove-the-heat-released-to-the-containment] 20 perform specific functions; e.g., emergency core cooling, containment heat 21 removal and containment atmosphere clean up following a postulated design 22 basis accident [(BBA3-an.d-that-this-system]. These systems must be designed 23 to permit appropriate periodic inspection and testing to ensure [its] their 24 integrity, [ capability,] and operability. General Design Criterion 1, " Quality 25 Standards and Records," of Appendix A to 10 CFR Part 50 requires that struc-26 tures, systems, and components important to safety be designed, fabricated, 27 erected, and tested to quality standards commensurate with the importance of 28 the safety function to be performed. This guide describes a method acceptable 29 to the NRC staff for implementing these requirements with respect to the 30 sumps / pools performing the functions of water source for the emergency core 31 cooling, containment heat removal, or containment atmosphere clean up [and O 32 containment-spray-systems]. This guide applies to light-water-cooled reactors. 33 34 1 Comparative text based on "For Comment" version published May 1983. 35 Proposed deletions from it are shown in bracket with overstrike ([-]) and 36 additions to it are shown underscored ( ). Tables and figures are not , 37 shown " comparative". " Active" revision was published June 1974 . *
- Page dates are: 05/06/85 4, 9, 20, 22-30; 05/10/85 21; 05/31/85 2, 3, 6, 16-18; 33/04/85 5, 7, 8, 10, 14, 19; 07/23/85 12, 13, 15, 31; 07/24/85 1, 11, 32. i 8508300343 850008 PDR REGGD 01.082 R PDR a
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i 1 Any guidance in this document related to information collection 2 activities has been cleared under OMB Clearance No. 3150-0011. 3 B. DISCUSSION 4 [Samps-or pump-intakes serve-the-emergency-core-cooling-system-(EEES3 5 and-the-containment-spray-system-(ESS)-by providing-for-the-coilection-of 6 re acto r- co ci ant- a n d- c hemi c aliy- rea c ti v e- s p ray- s oi nti o n- a nd- al l owi ng-i ts -reci r-7 eniation-for-additional-cooling-and-fissien product-removal. 8 Placement-of-the-EEES sumps-at-the-lowest-level practicai-ensures-maximum 9 utilization-of-available-recirculation-coolant:--However--there-may-be places 10 within-containment-where-coolant-eenid-accumulate-during-the-containment-spray 11 peried; providing-these-areas-with-drains-or-flow paths-to-the-sump-iecation 12 wili-minimize coolant-hoidup---This guide-does-not-address-the-design-of 13 such-drain paths---However;-since-debris generated-by-a-less-of-cociant-seeident 14 (t8EA)-can-migrate-to-the-sump-via-these pathwaysi-these-drains-are-best 15 terminated-in-a-manner-that-wili prevent-debris-from-being-transported-to 16 and-accumulating-en-the-EEES-sump---Appendix-A-addresses-concerns-related-to 17 debris-transport-and-the-effects-of-attendent-sump-screen-blockage. 18 Smali-drainage sumps-that-are-used-to collect-and-monitor-normal-leakage 19 flow-for-ieskage-detection-systems-within-containment-are-separate-from-the ' 20 EEES-sump-and-are-at a-lower-elevation-that-the-EEES sump-to-minimize-inadver-21 tent-spiiiover-inte-the-EEES-samp-due-to-minor-leaks-or-spilis-within-the 22 containment---The-ficer-adjacent-to-the-EEES-sump-would normally slope-down-23 ward- away-from-the-EEES-samp-toward-the-drainage-collection-sumps---This 24 downward-siope-away-from-the-EEES-sump-wili-minimize-the-cellection-of 25 debris-against-the-sump-screens]. 26 B.1 Pressurized Water Reactors 27 In pressurized water reactors (PWRs), the containment emergency sumps 28 provide for the collection of reactor coolant and chemically reactive spray 29 solutions following a loss-of-coolant accident (LOCA): thus the sumps serve 30 as water sources to effect long term recirculation for the functions of resi-31 dual heat removal, emergency core cooling and containment atmosphere cleanup. 32 These water sources, the related pump inlets and the piping between the sources ! i 33 and inlets are important safety components. The sumps servicing the emergency 1.82/2 05/31/85 1
_ _ _ _ _ _ _ _ _ _ - - - . s - r 1 core cooling systems (ECCS) and the containment spray systems (CSS) are 2 hereinafter referred to in this guide as ECC sumps. Features and relation 3 ships of the ECC sumps pertinent to this guide are shown in Figure 1. 4 The primary areas of safety concern regarding ECC sumps and pumps inlets 5 are: (a) post LOCA hydraulic effects, particularly air ingestion, (b) block-6 age of debris interceptors resulting from LOCA destruction of insulation and 7 _its transport, and (c) the combined effects of items (a) and (b) relative to 8 recirculation pumping operability (i.e., impact on net positive suction head 9 (NPSH) available at the pump inlet). 10 Debris resulting from a LOCA has the potential to block ECC sump debris 11 interceptors (i.e., trash racks, debris screens} and sump outlets resulting 12 [resuit] in a degradation of 2or loss of [ net positive-suction-head-(]NPSH[3] 13 margin. [The-t0EA generated] Such debris can be divided into the following 14 categories: (1) debris that is generated early in the LOCA period and is 15 transported by blowdown forces (i.e., jet forces from the break), (2) debris 16 that has a high density and will sink, but is still subject to fluid transport 17 if local recirculation flow velocities are high enough, (3) debris that has 18 an effective specific gravity near 1.0 and will float or sink slowly but 19 will nonetheless be transported by very low velocities, and (4) debris that 20 will float indefinitely by virtue of low density [or-composition] and will
- 21 be transported to and possibly thru the [ sump] debris screen. Thus, debris 22 generation [due-to-the-E06A], early transport due to blowdown loads, long-term 23 transport, and attendant [ screen] blockage [ effects] of debris interceptors 24 must be analyzed to determine head loss effects. Appendix A provides relevant 25 information [ guidelines] for such evaluations; References 1 through [5] 12 26 provide additional information relevant to the above concerns.
27 The design of sumps and their outlets includes consideration of the 28 avoidance of air ingestion and other undesirable hydraulic effects (e.g., 29 circulatory flow patterns, outlet designs leading to high head losses). 30 The location and size of the sump outlets within ECC sumps is important in 31 order to minimize air ingestion since ingestion is a function of submergence 32 level and velocity in the outlet piping. It has been experimentally deter-33 mined for PWRs that air ingestion can be minimized, or eliminated, if the 34 sump hydraulic design considerations provided in Appendix A are followed. 35 References 1, 3, 6, 7, and 8 provide additional. technical information relevant , 36 to sump ECC hydraulic performance and design guidelines. 1.82/3 05/31/85
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i 1 Placement of the ECC sumps at the lowest level practical ensures 2 maximum utilization of available recirculation coolant. However, since there
-3 may be places within containment where coolant could accumulate during the 4 containment spray period, these areas can be provided with drains or flow 5 paths to the sumps to prevent coolant holdup. This guide does not address 6 the design of such drains or paths. However, since debris can migrate 7 to the sump via these drains or paths they are best terminated in a manner 8 that will prevent debris from being transported to and accumulating on or 9 within the ECC sumps.
10 Containment drainage sumps are used to collect and monitor normal 11 leakage flow for leakage detection systems within containments. They are 12 separated from the ECC sumps and located at a lower elevation than the ECC 13 sumps to minimize inadverdant spillover into the ECC sumps due to minor 14 leaks or spills within containment. The floor adjacent to the ECC sumgs 15 would normally slope downward, away from the ECC sumps toward the drainage 16 collection sumps. This downward slope, away from the ECC sumps will minimize 17 the transport and collection of debris against the debris interceptcrs. 18 High density debris may be swept along the floor by the flow toward the 19 trash rack. A debris curb, upstre'am of and in close proximity to the rack, 20 will decrease the amount of such debris reachina the rack. 21 It is necessary to protect sump outlets by debris interceptors [ pump 22 intakes-by-screens-and-trash-racks-(coarse-outer-screens] of sufficient 23 strength to withstand the vibratory motion of seismic events, to resist Jet 24 loads and impact loads that could be imposed by missiles that may be generated 25 by the initial LOCA and to withstand the differential pressure loads imposed 26 by the accumulation of debris [or-by-trash]. Considerations in material 27 selection for the debris interceptors includes; long periods of inactivity, 28 that is no submergence; and possibly periods of operation, that is partial 29 or full submergence in a fluid that may contain chemically reactive materials. 30 Isolation of the ECC[5] sumps from high-energy pipe lines is an important 31 consideration in protection against missiles, and it is necessary to shield 32 the screens and [ trash] racks adequately from impacts of ruptured high-33 energy piping and associated jet loads from the break. When the screen and 34 [ trash] rack structures are oriented vertically Efecated-above-floor-level], 35 the adverse effects from debris collecting on them [ screen-structure] will , 36 be [at-a-minimum---Separating r] reduced. Redundant ECC[5] sumps [sereens] 1.82/5 06/04/85
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1 and sump outlets [ pump-suction intakes 3 are separated to the extent 2 practical [wili-help] to reduce the possibility that an event causing [s-3 partially-eiogged-screen-or-missile-damage-to-one-screen-would] the inter-4 ceptors or outlets of one sump to either be damaged by missiles or partially 5 clogged could adversely affect other pump circuits. [In-addition- proper 6 design-of-suction-intakes-wili-avoid-flow-degradation-by-air-ingestion; 7 swiri;-or-vertex-formation:] 8 [The-iocation-of-the pump-suction-intakes-within-the-EEES-sump-is-import-9 t a nt-i n- o rde r- to- mi ni mi z e- ai r-i n ge s ti o n- that-i s - a- f un c ti o n- o f- s ubme rge n c e 10 l ev ei- a nd- s ump - o u ti e t- v ei o ci ty:-- O th e r- f acto rs - to- c o n s i de r- a re- v e rte x- f o rma-11 tion-(which-can-iend-to-air-ingestion 3-and-swiri-effects-at-the-suction-inlet: 12 I t- h a s - b e e n- e xp e ri me nt al iy- de t e rmi n e d- t h a t- ai r-i n g e s ti o n- c a n- b e- mi ni mi z ed- e r 13 eliminated-if-the-hydraulic-design guidelines provided-in-Appendix-A are 14 followed:--References-1 7 6;-7 7 and-9 provide-additional-technical-infor-15 mation-relevant-to-sump-hydraulic performance-and-design guidelines: 16 As-noted-above;-the-design-of pump-section-intakes-ineindes-consideration 17 for-avoiding-air-ingestion-or-ether-undesirable-hydraulic-effects-ferg ; 18 swiri;-suction-inlet-design-effects):--Hewever;-for-small-amounts-of-air 19 ingestion;-the-recirculation pumps-ean-stifi-be-considered-operable provided 20 sufficient-NPSH-margin-is-demonstrated:--Appendix-A provides guidance-for 21 estimating-NPSH-margin-if-estimated-levels-of-air-ingestion-are-iew-fire ; 22 52%37--References-1-and-10 provide-additional-technical-findings-relevant-to 23 pump-operation-and-NPSH effects.] 24 It is expected that the water surface will be above the top of the debris 25 interceptor [ screen] structure after completion of the safety injection. 26 However, the uncertainties about the extent of water coverage on the [ screen] 27 structure, the amount of floating debris that may accumulate, and the potential 28 for early clogging do not favor the use of a horizontal top [ screen] interceptor. 29 Therefore, [because-of-this-uncertainty;] in computation of available interceptor 30 surface area no credit [can] is to be taken [in-computing-the-available-surface 31 area] for any [ top] horizontal [seeen] interceptor surface, and the top of 32 the interceptor [sereen] structure [would] is preferably [be] a solid [ deck] 33 cover plate to provide additional protection from LOCA generated loads and 34 designed to provide for the venting of any trapped air. 35 Debris which is small enough to pass through trash rack and which could , 36 clog or block the debris screens or outlets is to be analyzed for head loss l 1.82/6 05/31/85
1 effects. Screen and sump outlet blockage will be a function of the types and 2 quantities of insulation debris that can be transported to these components. 3 A vertical inner debris screen would impede the deposition or settling of
] 4 debris on screen surfaces and thus help to assure the greatest possible free-5 flow through the fine inner debris screen. Slowly settling debris that is 6 smcll enough to pass through the trash rack openings could block the debris 7 [ inner] screens if the coolant flow velocity is too great to permit the bulk 8 of the debris to sink to the floor level during transport. [A-vertically 9 mounted-inner-screen-would-minimize-settling-of-debris-en-the-screen-surface-10 and-if-sufficient-anblocked-screen-area-is provided-to-keep] M the coolant 11 flow velocity [at] ahead of the screen is at or below approximately [6] 5 12 cm/sec (0.2 ft/sec), debris with a specific gravity of 1.05 or more will 13 likely settle before reaching the screen surface and thus help to prevent 14 undue clogging of the screen.
15 The size of openings in the [ fine] screens is dependent on the physical 16 restrictions [--inciading-spray-nozzies-] that may exist in the systems that 17 are supplied with coolant from the ECC[S] sump. The size of the mesh of 18 the fine debris screen is determined based on consideration of a number of 19 factors including the [The] size of openings in the containment spray nozzles, 20 coolant channel openings in the core fuel assemblies, and pump design 21 characteristics, for example seals, bearings, and impeller running clearances 22 [wiii-need-to-be-considered-in-determining-the-size-of-the-fine-screen]. 23 As noted above, degraded pumping can be caused by a number of factors, 24 including plant design and layout. In particular, debris blockage effects 25 or debris interceptor and sump outlet configutations, and post LOCA hydraulic 26 conditions (e.g. , air ingestion) must be considered in a combined manner. 27 Small amounts of air ingestion, 52% i.e., will not lead to severe pumping 28 degradation if the " required" NPSH from the pump manufacturer's curves is 29 increased based on the calculated air ingestion. Thus the combined results 30 of all post LOCA effects need to be used to estimate NPSH margin, as calcu-31 lated for the pump inlet. Appendix A provides information for estimating NPSH 32 margins in PWR sump designs, where estimated levels of air ingestion are low 33 (52%). References 1 and 8 provide additional technical findings relevant to 34 NPSH effects on pumps performing the functions of residual heat removal, emer-3,5 gency core cooling and containment atmosphere cleanup. When air ingestion is 36 5 2%, compensation for its effects may be achieved without redesign if the 1.82/7 06/04/85
j - J 1 l 1 "available" NPSH is greater than the " required" NPSH plus a margin based on 2 the percent air ingestion. If air ingestion is not small, redesign of one or 3 more of the recirculation loop components may be required to achieve satis-4 factory design. 5 [ Potential-blocking-of-the-fine-screen-would-reduce-the-free-flow-area 6 thr agh-the-screen--and-it-is-essential-that-sufficient-fiow-area-be provided 7 to-maintain-adequate-NPSH-margint 8 A-significant-consideration-is-the potential-for-degraded pump performance 9 that-could-be-caused-by-a number-of-factors--ineinding-the-loss-of-NPSH-margin: 10 ff-the-NP5H-availabie-to-a pump-is-not-sufficient--degraded pump performance 11 wili-significantly-reduce-the-capability-of-the-system-to-accomplish-its 12 safety-fanetion:--The pressure-drop-across partially-for-completely-biocked 13 screens-wili-reduce-available-NPSH-margin-and-can-be-calculated-based-on-the 14 debris-bioekage-evaluation-methods-cutiined-in-Appendix-A.] 15 To ensure the [ readiness] operability and structural integrity of the 16 racki and screens, access openings are necessary to permit inspection of 17 the [inside] ECC sump structures and outlets [ pump-section-iniet-openings]. 18 Inservice inspection [for-trash] of racks, screens, vortex suppressors, and 19 sump outlets [pamp-section-iniet-openings], including visual examination 20 for evidence of structural degradation or corrosion can be performed on a 21 regular basis at every refueling period downtime. Inspection of the ECC[S] 22 sump components is to be made late in the refueling period [would-help] to 23 ensure the absence of construction [ debris] trash in the ECC[S] sump area. 24 B.2 Boiling Water Reactors 25 In boiling water reactors (BWR) the suppression pool; in conjunction 26 with the drywell, downcomers and vents; serves as the water source for 27 effecting long-term recirculation cooling and for fission product removal. 28 This source, the related pump inlets, and the piping between them are 29 important safety components. These components are hereinafter referred to 30 in this guide as the suppression pool. Features and relationships of the 31 " suppression pool" pertinent to this guide are shown in figure 2. As with 32 the ECC sumps in PWRs there are similar concerns with the performance of 33 the suppression pool and pump inlets namely, (a) post-LOCA hydraulic effects, 34 particularly air ingestion, (b) blockage of debris interceptors resulting e 1.82/8 06/04/85 _ _ . _ _ . _ _ _ - _ . _ a
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1 from LOCA destruction of insulation and its transport (including suppression 2 pool bulk velocity effects), and (c) the combined effects of items (a) and . 3 (b) relative to recirculation pump operability (e.g., the impact on NPSH 4 available at the pump inlet). References 1 and 7 provide data on the 5 performance and air ingestion characteristics of BWR configurations. 6 As in the case of PWRs, it is desirable to include consideration of the 7 use of debris interceptors in BWR designs to protect the pump inlets. How-8 ever, the location of the debris interceptors need not be restricted to the 9 pool itself. Debris interceptors or equivalent plant structures in the drywell 10 in the vicinity of the downcomers or vents could serve effectively in reducing 11 debris transport to the pump inlets. 12 Similarly, the smallest the opening in the debris interceptors is depen-13 dent on the physical restrictions that may exist in the systems served by 14 the suppression pool. For example, spray nozzle clearances, coolant channel 15 openings in the core fuel assemblies, and pump design characteristics; for 16 example seals, bearings and impeller running clearances will need to be 17 considered in the design. 18 C. REGULATORY POSITION 19 C.1 Pressurized Water Reactors 20 Reactor building sumps that are designed to be a source of water for 21 the performance of the functions of emergency core cooling 2 [ system-(EEES3-or 22 the] containment [ spray-system-(ESS3] heat removal or containment atmosphere 23 clean up following a loss-of-coolant accident (LOCA) should meet the following 24 criteria: 25 a[1]. A minimum of two sumps should be provided, each with sufficient 26 capacity to service one of the redundant halves of the ECCS and CSS [ systems]. 27 b[2]. To the extent practical, the redundant sumps should be physically 28 separated by structural barriers from each other and from high-energy piping 29 systems to preclude damage to the sump components (e.g., racks, screens and 30 sump outlets (suction pipes]) by whipping pipes or high-velocity jets of water 31 or steam. 32 c[3]. The sumps should be located on the lowest floor elevation in : 33 the containment exclusive of the reactor vessel cavity. The sump [4ntake] 1.82/10 06/04/85
_, _ _ . .,u. . . . 4 1 outlets should be protected by at least two vertical [ly-mounted screens] [ 2 debris interceptors: [(13] {il a fine inner debris screen and (ii) [(23] 3 a[n] coarse outer trash rack to prevent large debris from reaching the debris 4 [ fine-inner] screen. [The-samp-screens-should-not-be-depressed-below-the 5 floor-elevation:] A curb should be provided [around-the periphery] upstream 6 of the trash racks [sereens] to prevent high-density debris [(ire:--fine 7 particciates3] from being swept along the floor into the sump. 8 d[4]. The floor in the vicinity of the ECC[S] sump should slope grad-9 ually downward away from the sump. 10 e[5]. All drains from the upper regions of the reactor building should 11 terminate in such a manner that direct streams of water, which may contain 12 entrained debris, will not impinge on the debris interceptors [ filter assemblies]. 13 f[6]. The strength of the trash racks should be adequate to protect the 14 [ inner] debris screens from missiles and other large debris [ generated-by-the 15 E06A]. Each interceptor should be capable of withstanding the loads imposed 16 by missiles, by the accumulation of debris and by head differentials due to 17 blockage. 18 g.[7. The-design-coolant veiocity-at-the-fine-inner-screen-shoaid-be 19 approximately-6-em/see-(0:2-ft/see).] The available [ screen] interceptor 20 surface area used in determining the design coolant velocity should be cal-21 culated to conservatively account for [samp-screen] blockage that [might] 22 may result [from-debris generation-and-transport]. Only the vertical [ sump 23 screens] interceptor area that is below the design basis water level should 24 be considered in determining available surface area. Fibrous type insulation 25 debris should be considered as uniformly distributed over the available debris 26 screen area. Blockage should be calculated based on levels of destruction 27 estimated (See also Ref. 1 and 12). 28 h[8]. Evaluation [s] or confirmation of [(1)] [il sump hydraulic perfor-29 mance (e.g., geometric effects and air ingestion), (ii) [(23-t0EA generated] 30 debris effects (e.g., debris transport [and-screen] interceptor blockage 1 31 and head loss), and [(33] (iii) the combined impact on [pamp] NPSH [ margin] 32 available at the pump inlet should be performed to ensure that long-term 33 recirculation cooling can be accomplished. [Samp-hydrealic effects-and-debris 34 bioekage-considerations-that-conid-have-an-adverse-impaet-on-NPSH-margin-should 35 be-considered-in-the-evaluation-of-the-EEES pump performance] Such evaluation 36 should arrive at a determination of NPSH margin, as calculated at the pump 1.82/11 07/24/85 s k
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; 1 inlet. An assessment of recirculation pump seal and bearing assembly design ) 2 susceptibility to failure due to particulate ingestion and particulate abrasive 3 effects should be made to protect against degradation of long term recircula-y 4 tion pumping capacity.
5 1[9]. The top of the [ deck] debris interceptor structures should be a 6 solid cover plate that is designed to be fully submerged after a LOCA and 7 completion of the ECC injection. It [The-solid-deck] should be designed to 8 ensure the venting of [any] air otherwise trapped underneath. 9 J[10]. The [ trash-rack-and-screens] debris interceptors should be 10 designed to withstand the vibratory motion of seismic events without loss of 11 structural integrity. 12 k(11]. The size of openings in the [ fine] debris screens should be 13 based on the minimum restriction found in systems served by the pumps 14 performing the recirculation function. The minimum restriction should take 15 into account the requirements of the systems served. 16 h [12.- Pamp-intake-iocations-within-the-samp] Sump outlets should be 17 [carefuliy-considered] designed to prevent degradation of pump performance by 18 [the-effects-of-such-conditions-as] air ingestion and other adverse hydraulic 19 effects (e.g., circulatory flow patterns [Samp-induced-swiri], high intake-20 head losses). 21 m[13]. Materials for [ trash-racks and-screens] debris interceptors 22 should be selected to avoid degradation during periods of inactivity and 23 operation and should have a low sensitivity to such adverse effects as stress-24 assisted corrosion that may be induced by the chemically reactive spray 25 during LOCA conditions. X n[14]. The [ trash-rack-and-screen] debris interceptor structures, should 27 include access openings to facilitate inspection of the n structures, any 28 vortex suppressors and the Epamp-section-intake) sump outlets. 29 o[iS]. Inservice inspection requirements for ECC[S] sump components 30 (e.g. debris interceptors [ trash-racks--screens], any vortex suppressors, 31 and [pamp-section-iniets) sump outlets) should include: 32 i[a]. Inspection [of-EEES-samp-components] during every 33 refueling period downtime, and i 1.82/12 07/23/85
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1 ii[b]. A visual examination [of-the-components] for eridence 2 of structural distress or corrosion. 3 C.2 Boiling Water Reactors 4 The suppression pool, which is the source of water for the performance 5 of functions of emergency core cooling, containment heat removal and contain-6 ment atmosphere cleanup following a loss-of-coolant accident (LOCA) in com-7 bination with the vents and downcomers between drywell and wetwell, should 4 8 contain the following features: 9 a. The inlet of pumps performing the above functions should be protected 10 by two debris interceptors: 11 1. a fine downstream debris screen; and 12 11. a coarse upstream trash rack to prevent large debris from 13 reaching the debris screen. 14 It should be noted that certain design features of BWRs may perform the 15 equivalent function of trash racks and debris screens. Design features 16 such as deflectors and suction strainers may be considered equivalent 17 to trash racks and debris screens. Hereafter " trash rack" or " debris 18 screen" includes equivalent plant features. 19 b. If it is demonstrated that significant amounts of debris will not 20 be generated within the wetwell then the trash rack may be located in the 21 drywell or the downcomer system between the drywell and wetwell. 22 c. All drains from the upper regions of the reactor building should 23 terminate in such a manner that direct streams of water, which may contain 24 entrained debris, will not impinge on the debris interceptors. 25 d. The strength of the trash rack should be adequate to protect the 26 debris screen from missiles and other large debris. Each interceptor should 27 be capable of withstanding the loads imposed by missiles, by debris and by 4 28 head differentials due to blockage. ~ 29 e. Bulk suppression pool velocity due to recirculation 'peration c should 30 be considered for both debris transport and coolant velocity computations. 31 f. The available interceptor area used in determining the design coolant 32 velocity should conservatively account for blockage that may result. Fibrous 33 type debris should be assumed to be uniformly distributed over the available 1.82/13 07/23/85
V e .
. . . . _ c. . . ._ .
~~
.1 d ..
*{i .
k t ', 1 debris screen surface. Blockage should be calculated based on levels of L 2 destruction estimated. (See also Ref. 1 and 12.) 3 c. Evaluation or confirmation of (1) suppression pool hydraulic perfor-4 mance (e.g., geometric effects and air ingestion), (ii) debris effects (e.g., 5 debris transport, interceptor blockane and head loss, and particulates clogging 6 of pumt, seals), and (iii) the combined impact on NPSH available at the pump 7 i,nlet should be performed to ensure that long-term recirculation ecoling can 8 be accomplished. An assessment of recirculation pump seal and bearing 9 assembly design susceptibility to failure due to particulate in,qestion and 10 particulate abrasive effects should be made to protect against oegradation of 11 long term recirculation pumping capacity. 12 h. The debris interceptors should be designed to withstand the vibratory 2 13 motion of seismic events without loss of structural integrity. 14 1. The si e of openings in the screens should be based on the minimum 15 restriction found in systems served by the suppression pool. The minimum 16 restriction should take into account the operability of the systems served. 17 j. The pool outlets to the recirculation pumps should be designed to 18 prevent degradation of pump performance through air ingestion and other 19 adverse hydraulic effects (e.g. , circulatory flow patterns, high intake-head 20 losses). . 21 k. Material for debris interceptors should be selected to avoid degrada-22 tion during periods of inactivity and normal operations, and should be com-23 patiblewiththecharacteristicsoJthesprayduringLOCAevents. 24 1. Inservice inspection requirements should include: 25 (i) inspection during every refueling period downtime: 26 (ii) a visual examination for evidence of structural distress or 27 corrosion and 28 (iii) an inspection, far evidence of debris or trash, of (I) the 29 wetwell air spaces and (II) the dry well floor region including 30 the vents, downcomers and deflectors. 1.82/14 06/04/85
l . . ~%' .. ~ .:: ~. .z.-- . . z. . .-- : . - - . . . - J t . .
,1
~i 1 fi[b]. A visual examination [of-the-components] for evidence 2 of structural distress or corrosion. 3 C.2 Boiling Water Reactors 4 The suppression pool, which is the source of water for the performance 5 of functions of emergency core cooling, containment heat removal and contain-6 ment atmosphere cleanup following a loss-of-coolant accident (LOCA) in com-7 bination with the vents and downcomers between drywell and wetwell, should 8 contain the following features: 9 a. The inlet of pumps performing the above functions should be protected 10 by two debris interceptors: 11 1. a fine downstream debris screen; and 12 11. a coarse upstream trash rack to prevent large debris from 13 reaching the debris screen. 14 It should be noted that certain design features of BWRs may perform the 15 equivalent function of trash racks and debris screens. Design features 16 such as deflectors and suction strainers may be considered equivalent 17 to trash racks and debris screens. Hereafter " trash rack" or " debris 18 screen" includes equivalent plant features. 19 b. If it is demonstrated that significant amounts of debris will not 20 Le generated within the wetwell then the trash rack may be located in the 21 drywell or the downcomer system between the drywell and wetwell. 22 c. All drains from the upper regions of the reactor building should 23 terminate in such a manner that direct streams of water, which may contain 24 entrained debris, will not impinge on the debris interceptors. 25 d. The strength of the trash rack should be adequate to protect the 26 debris screen from missiles and other large debris. Each interceptor should 27 be capable of withstanding the loads imposed by missiles, by debris and by 28 head differentials due to blockage. 29 e. Bulk suppression pool velocity due to recirculation operation should 30 be considered for both debris transport and coolant velocity computations. 31 f. The available interceptor area used in determining the design coolant 32 velocity should conservatively account for blockage that may result. Fibrous 33 type debris should be assumed to be uniformly distributed over the available 1.82/13 07/23/85
, __ _ . . _ .m .C ._ _ _ , ._ . _ - -
.t l
F #
.i 1 debris screen surface. Blockage should be calculated based on levels of 2 destruction estimated. (See also Ref. 1 and 12.) . 3 g. Evaluation or confirmation of (i) suppression pool hydraulic perfor-4 mance (e.g., geometric effects and air ingestion), (ii) debris effects (e.g.,
5 debris transport, interceptor blockage and head loss, and particulates clogging 6 of pump seals), and (iii) the combined impact on NPSH available at the pump 7 inlet should be performed to ensure that long-term recirculation cooling can 8 be accomplished. An assessment of recirculation pump seal and bearing 9 assembly design susceptibility to failure due to particulate ingestion and 10 particulate abrasive effects should be made to protect against degradation of 11 long term recirculation pumping capacity. 12 h. The debris interceptors should be designed to withstand the vibratory
. 13 motion of seismic events without loss o# structural integrity.
14 i. The size of openings in the screens should be based on the minimum 15 restriction found in systems served by the suppression pool. The minimum 16 restriction should take into account the operability of the systems served. 17 j. The pool outlets to the recirculation pumps should be designed to 18 prevent degradation of pump performance through air ingestion and other
. 19 adverse hydraulic effects (e.g., circulatory flow patterns, high intake-head 20 losses).
21 k. Material for debris interceptors should be selected to avoid degrada-22 tion during periods of inactivity and normal operations, and should be com-23 p_atible with the characteristics of the spray during LOCA events. 24 1. Inservice inspection requirements should include: 25 (i) inspection during every refueling period downtime 26 (ii) a visual examination for evidence of structural distress or 27 corrosion and 28 (iii) an inspection, for evidence of debris or trash, of (1) the 29 wetwell air spaces and (II) the dry well floor region including 30 the vents, downcomers and deflectors. 1.82/14 06/04/85 1 L
1 D. IMPLEMENTATION 2 ) The purpose of this section is to provide information to applicants 3 regarding the NRC staff's plans for using this regulatory guide. This 4 regulatory guide has been developed from an extensive experimental and 5 analytical data base. The applicant / licensee is free to select alternate 6 calculation methods which are founded on substantiating experiments and/or Ifmiting analytical considerations. [This proposed revision-to-the-regulatory 7 8 guide-has-been published-to--encourage public participation-in-its-develop-9 ment-] Except in those cases in which the applicant / licensee proposes an 10 alternative method for complying with the specified portions of the Commis-11 sion's regulations, the methods described in this [the-revised-active] guide 12 [ reflecting pubiie-comments] will be used by the NRC staff in its evaluation 13 of all: 14 1) standard reference system preliminary design applications or final 15 design applications that are docketed afteri ; 16 2) licenses to manufacture that are docketed after2 ; 17 3) construction permit applications that are docketed after2 ; 18 4) operating license applications that are docketed after 2 19 Ethe-design-and constraction of-samps-for-emergency-core-cooling-and-cen-20 tainment-spray-systems---in-addition--the-NRE-staff-intends-to-ase-this guide 21 to-evainate-the-design-and-construction-of-samps-in plants-for-which-an 22 operating-license-has-been-issued;-the-implementation-date-wiii-be-specified 23 in-the-active gaids]. 24 2 25 Six (6) months after issuance of the Regulatory Guide ) 1.82/15 07/23/85
^
. - . . _ . . . . . - - - - :. . . ~ .. - , .L - . . - . ..
l 1 APPENDIX A 2 GUIDELINES FOR REVIEW OF 3 SUMP DESIGN AND WATER SOURCES FOR
- 4 EMERGENCY CORE COOLING 5 [EEES-SUMPS]
6 1. General 7 The ECC[S] sump performance should be evaluated under possible post LOCA 8 conditions to determine design adequacy for providing long-term recirculation. 9 Technical evaluations can be subdivided into (1) Sump Hydraulic Performance, 10 (2) [ effects-of] LOCA-Induced Debris Effects, and (3) Pump Performance Under 11 Adverse Conditions. Specific considerations within these categories, and the 12 combining thereof, are shown in Figure A-1. Determination that adequate NPSH 13 margin exists at the pump inlet under all postulated post-LOCA conditionc ic 14 the final requirement. 15 2. Sump Hydraulic Performance 16 Sump hydraulic performance (with respect to air ingestion potential) 17 can be evaluated on the basis of submergence level (or water depth above the 18 sump [saction] outlets) and required pumping capacity (or [samp-section entiet] 19 pump-inlet velocity). The water depth above pipe centerline (s) and [saction]
~
20 inlet pipe velocity (U) parameters can be expressed nondimensionally as the 21 Froude number: ' 22 23 .Froudenumber=U//gs 24 where g is the acceleration due to gravity [ gravitational-constant]. Extensive 25 experimental results have shown that the hydraulic performance of ECC[5] sumps 26 (particularly air ingestion potential) is a strong function of Froude number. 27 Other nondimensional parameters (e.g., Reynolds number and Weber number) are 28 of secondary importance. 29 Sump hydraulic performance can be divided into three performance 30 categories: 31 a. Zero air ingestion, [thas-avoiding pump-cavitation-] which requires 32 no vortex suopressors or increase of the " required" NPSH above that 33 from the pump manufacturer's curves. 1.82/16 05/31/85 t
l. t l 1 b. Air ingestion $2%, a conservative level [at-which] where degradation of 2 pumping capability is not expected based on an increase of the 3 " required" NPSH (see Figure A-2), 4 c. Use of vortex suppressors to reduce air ingestion effects to [a 5 negligibie-level] zero. 6 For PWRs zero air ingestion can be [ ensured] assured by use of the design 7 [ criteria] guidance set forth in Table A-1. Determination of those designs 8 having air ingestion levels 52% [or-less] can be obtained using correlation 9 given in Table A-2 and the attendant sump geometric envelope [ piecement,]. 10 Geometric and screen guidelines for PWRs are contained in Tables A-3.1, A-3.2, 11 A-4, and A-5. Table A-6 presents design guidelines for vortex suppressors 12 [ ion-devices] that have shown the capability to reduce air ingestion to zero. 13 These guidelines (Tables A-1 through A-6) were developed from extensive full-14 scale sump hydraulic tests and provide a [ concise] rapid means of assessing 15 sump hydraulic performance. If the PWR sump design deviates significantly 16 from the design boundaries noted, then similar performance data should be 17 obtained for verification of adequate sump hydraulic performance. 18 For BWRs, full scale tests of pool outlet designs for recirculation 19 pump have shown that air ingestion is zero for Froude numbers of less than 20 0.8 with a mininum submergence of 6 feet, and operation up to a Froude number 21 of 1.0 with the same minimum submergence may be possible before air ingestion 22 levels of 2% may occur (see also References 1 and 7). 23 3. [ Effects-of] LOCA-Induced Debris Effects 24 Assessment of LOCA debris generation and determination of possible i 25 debris interceptor [ sump-screen] blockage is complex. The evaluation of 26 this safety question is dependent on the types and quantities of insulation t 27 employed, the location of such insulation materials within containment and 28 with respect to the sump location, the estimation of quantities of debris 29 generated by a pipe break, and the migration of such debris to the [semp 30 screen] interceptors. Thus [ estimates-of semp-screen] blockage estimates 31 are specific to the insulation materia 11 [and] the plant design and require 32 consideration of such effects as are outlined in Table A-7. 33 Since break jet forces are the dominant debris generator, the predicted ,. 34 jet envelope will determine the quantities and types of insulation debris. 1.82/17 05/31/85
B l 1 Figure A-3 provides a three region model which has been developed from 2 analytical and experimental considerations, as identified in reference 1. 3 The destructive results of the break jet forces will be considerably different 4 for different types of insulation and must be individually addressed. The 5 insulation type, how and whether it is encapsulated, and how it is fastened 6 to the insulated surfaces, all have significant influence on the maximum 7 volume of insulation debris generated. Region I represents a total destruc 8 tion zone; Region II a region where high levels of damage are possible 9 depending on insulation types, whether encapsulation is employed, methods of 10 attachment, etc.; Region III a region where dislodgement of insulation in 11 whole, or as-fabricated, segments is likely occur. A more detailed discussion 12 of these considerations is provided in Reference 1. Use of the outer boundary 13 of Region II for estimating maximum volumes of total insulation destruction is 14 considered a conservative bounding condition. 15 [Since-evaluation-of-debris-effects-is-dependent-en-the-material-type 16 and-aiso-on-recirealation-flow-velocities;-a-series-of-iimiting-evaluations 17 can-be performed;-these-are-outlined-in-Tables-A-8-and-A-9---Table-A-8 provides 18 a-concise-means-of-evaluating-the potential-for-debris-transport-at-various 19 flow-velocities-for-three-major-types-of-insniation:--Table-A-9 provides-a 20 rapid-means-of-assessing-the-transport-of-fibrous-insaiation-debris-and quanti-21 fying-the-volume-of-such-debris-that-could-resuit-in-ioss-of-50%-of-the-NPSH 22 requirement---toose-fibrous-debris wiii-be-transported-by-veiecities-as-lew 23 as-8:2-ft/see-(6-em/see)-] 24 ff-Table-A-8-or-Tabie-A-9-does-not-readify-identify-negligibie-or-con-25 servatively-low-leveis-of-samp-screen-blockage;-the-considerations-catiined 26 in-Table-A-7-mast-be-evainated-on-a piant-specific-basis:--Figure-A-E-is 27 provided-for-additional guidance-in-estimating-such-debris-bioekage-effects; 28 and-rescits-obtained-from-such-an-evaluation-would-be-used-to-estimate-the 29 impact-on-NPSH-margin.] References 1, [27-47] 9, 10, 11 and [5] 12 provide 30 more detailed information relevant to assessment of debris [ effects] 31 generation and transport. 32 4. Pump Performance Under Adverse Conditions 33 The pump industry historically has determined net positive suction head 34 requirements for pumps on the basis of a percentage degradation in [ performance] ; 35 pumping capacity . The percentage has [at-times] been at times arbitrary, 1.82/18 05/31/85
2 '
;=
1 ,
.y .
(1I j 1 but [is] generally in the range of 1% to [1-] 3%. A 2% limit on allowed air 2 ingestion is recommended since higher levels have been shown to initiate degra-
~
3 dation of pumping capacity. 4 The 2[ volume] percent-volume limit on sump air ingestion and the NPSH 5 requirements act independently. However, air ingestion levels less than 2% 6 can also affect NPSH requirements [ conditions---Figure-A-B-is-therefore 7
, provided-as-a guide-for evaluating-conditions-at-the pump-iniet--commencing 8 at-the-sump-] If air ingestion is indicated, correct the NPSH requirement 9 from the pump curves [should-be-corrected] by the relationship:
1 " b" required [(airAiquid3](a < p2%) = NPSH required (liquid)
- 0 12 where p = 1 + 0.50a p , andpa is the air ingestion rate (in percent by 13 volume) at the pump inlet flange.
4 14 5. Combined Effects 15 As shownr in Figure A-1, three-interdependent effects (i.e. , sump hydraulic 16 performance, [t0EA] debris effects, and pump operation under adverse conditions)
~
, 17 require evaluation for determining long-term recirculation capability. 18 Figure A-[4] 2 provides a logic diagram for combining these considerations to 19 evaluate the ECC[S] sump design and expected performance. The same logic applies 20 to BWR design evaluations of suppression pools and the outlets to recircula-21 tion pumps. 1.82/19 06/04/85
1 Table A-1 2 Hydraulic Design Guidelines
- for Zero Air Ingestion 3
4 Item Horizontal Outlets Vertical Outlets Minimum submergence, s (ft) 9 9 8 (m) 2.7 2.7 1 Maximum Froude Number, Fr 0.25 0.25
- . Maximum Pipe Velocity, U (ft/s) 4 4 15 (m/s) 1. 2 1.2 19
*These guidelines were established using experimental results from 18 references 3, 4 and 5 and are based on sumps having a right 19 rectangular shape.
e 1,..,.... ii o f - - / a a -- __ ..... i 5I
, "o$!Y'u$
< Ai WN.h L i S UO- ! r, = g ,
;,m.
alsocr/n 1.82/20 05/06/85 l l u
.. . . _ . . _ _ _ _ . . _ _ _ -m l
'l Tcblo A-2 2 Hydraulic Design Guidelines for Air Ingestion 5,2%
3' Air ingestion a is empirically calculated as i 4 a=a + (a1 x Fr) 5 where a and at arecoeificientsderivedfromtest 6 Eesultsahgiveninthetablebelow. 3 , Horizontal Outlets Vertical Outlets Item Dual Single Dual Single
.}
[.3 Coefficient a, -2.47 -4.75 -4.75 -9.14,
- b. Coefficient at 9.38 18.04 18.69 35.95f 13 Minimum Submergence, s (ft) 7.5 8.0 7.5 10 19 (m) 2.3 2.4 2.3 3.1 32 Maximum Froude Number, Fr 0.5 0.4 0.4 0.3 Maximum Pipe Velocity, 24 U (ft/s) 7.0 6.5 6.0 5.5 25 (m/s) 2.1 2.0 1.8 1.7 Maximum Screen Face Velocity 29 (blocked and minimum 30 submergence) (ft/s) 3.0 3.0 3.0 3.0 31 (m/s) 0. 9 0.9 0.9 0. 9 Maximum Approach Flow 34 Velocity (ft/s) 0.36 0.36 0.36 0.36 35 (m/s) 0.11 0.11 0.11 0.11
$h Maximum Sump Outlet 38 Coefficient C L
1.2 1.2 1.2 1.2 39 c 1,..o..
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ll ",$'f *g il m u--P--- l-6~ - r, = g,.m.. anoar/n 1.82/21 05/10/85
i
)
i, t 1 Table A-3.1 2 GE0 METRIC DESIGN ENVELOPE GUIDELINES FOR HORIZONTAL SUCTION OUTLETS **
, 3 ;
4 Size Sump Outlet Position
- Screen
~
h Min. . , 7 Sump Aspect Perimeter Min. Area , 8 Outlet Ratio (ft) (m) ey/d (B - ey)/d c/d b/d f/d ex/d 2 (ft ) (,2) : 10 Dual 1 to 5 36 11 >4 75 7 11
->l ->3 ->1.5 ->l ->1.5 !-
12 ? .: 13 Single 1 to 5 16 4.9 - 35 3.3 l
}$
- Preferred location.
16 ** Dimensions are always measured to pipe centerline. , , H h N Tresh Rock and 2 L ; Debrie Screen r- 1I ll II 3 4i 0 ->4 75 7 11
->l ->l ->l -> 1. 5 13 Single 1 to 5 16 4.9 $1. 5 35 3.3
- Preferred location. '
y 16 ** Dimensions are always measured to pipe centerline. 18 N Traoh Rock Debris Screen 1 l
,l cc _______-____ , :
1l l ll ll u 4.. ..
,y l --{+,,
y ' 17 [" ;, ' 18 lll Ill " '
.. O I
19 llI ' I o *" I M '
- - J )l *s m* ' * * .'**.,u a . . . . . . .
20 -- - - - - - - - - ' ' 21 y l 22 .;.,l : ,.. ! e ., , _ , , , *, _ , , , , , , !' (
~
Aspect Ratio = UB o : L ; Minimum Posimeter = 2tL + 8) .
= 8 Q =
C/f0ST/11
._ =_ a_ .. 1. . m . _ _ _ _
_.._.:.._u...__ -. _ . . . . _ _ _ _ l 1 Table A-4
; 2 Additional Guidelines Related to Sump Size and Placement . .;:' 3 1. The clearance between the trash rack and any wall or obstruction 4 of length A equal to or greater than the length of the adjacent 5 screen / grate (Bs *Ps l ) should be at least 4 ft (1.2 m).
6 2. A solid wall or large obstruction may form the boundary of the sump 7 on one side only, i.e., the sump must have three sides open to the ' 8 approach flow. 9 3. These additional guidelines should be followed to ensure the validity 10 of the data in Tables A-1, A-2, A-3.1, and A-3.2.
- I > L, v g/#########/##/A> -
4h N * (min) : L o r============- q
" ii li Ii It 11 i B, 8 Sump Pit ll . Il Trash Rack
!I U U Debris Screen
" i'
_-44.___== v 2442.s v v u b ( )
- L : ,,
r,- l pl 7ll ll ll 11 B, B Il Sump Pit ll l>E s - ll ll llI 11
" !! n n l e==rs=== == x==+l i Trash Rack and Debris Screen ofgeg7/77 1.82/24 05/06/85 ;
a
= __
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3 1 Table A-5 i 2 Design Guidelines
- for Interceptors and Cover Plate 1 3 1. Screen area should be obtained from Table A-3.1 and A-3.2.
4 2. Minimum height of interceptors should be 2 feet (0.61 m). 5 3. Distance from sump side to screens, gs, may be any reasonable value. 6 4. Screen mesh should be 1/4 inch (6.4 mm) or finer. 7 5. Trash racks should be vertically oriented 1- to 1-1/2-inch (25- to 38-mm) 8 standard floor grate or equivalent. 9 6. The distance between the debris screens and trash racks should be 6 inches 10 (15.2 cm) or less. 11 7. A solid cover plate should be mounted above the sump and should fully 12 cover the trash rack. The cover plate should be designed to ensure the 13 release of air trapped below the plate (a plate located below the 14 minimum water level is preferable). Golid Cover Plate hf 0:: f_# - .. Trash Rack V . .t$' .j.;,h,5- <: (m Debria Screen
%" Meeh (max)
. 20 : 21 *See Ref 1. 1.82/25 05/06/85
.- l 1 Table A-6 2 Guidelines for Selected Vortex Suppressors*
3 1. Cubic arrangement of standard 1-1/2-inch (38-mm) deep or deeper floor 4 grating (or its equivalent) with a characteristic length, yt , that is 5 23 pipe diameters and with the top of the cube submerged at least 6 inches 6 (15.2 cm) below the minimum water level. Noncubic designs with 1 23 pipe 7 diameters for the horizontal upper grate and satisfying the depth,and 8 distances to the minimum water level given for cubic designs are acceptable. 9 2. Standard 1-1/2-inch (38-mm) or deeper floor grating (or its equivalent) 10 located horizontally over the entire sump and containment floor inside the 11 screens and located below the lip of the sump pit. 12 13
- Tests on these types of vortex suppressors at Alden Research Laboratory have 14 demonstrated their capability to reduce air ingestion to'zero even under the 15 most adverse conditions simulated.
l Design #1: ' 7 ,,,, and Tee M n V, oet,de Screen, i y,,; , ;;;;::; _= n
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a n :=,
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a o :"-
- Trash Rock o..i., n
,Q
~ ' -
Minimum y- o ~. Water Level fi
- ;.t
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si.no., i.64 fk[
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.: 13 6.!: :
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- Y' 1.82/26 05/06/85
w .- .. = . :-. - - . -. . T- .. z- _ _ . . 1
'1 4
i 1 Table A-7 l' 2 Debris Assessment 3 CONSIDERATION EVALUATE i 4 1. Debris generator - Major pipe breaks & location
- 5 (pipe breaks & location -
Pipe whip & pipe impact 6 as identified in SRP - Break jet expansion envelope
. 7 Section 3.6.2) (This is the ma.ior debris 4 8 generator) 9 2. Expanding jets -
Jet expansion envelope j 10 - Piping & plant components
.1 11 targeted (i.e., steam 12 generators) 13 . -
Jet forces on insulation 14 - Insulation that can be 15 destroyed or dislodged by 16 blowdown jets
~
17 - Survivability under jet Ji 18 loading. 19 3. Short-term debris - Jet / equipment interaction i 20 transport by blowdown - Jet / crane wall interaction i 21 jet forces) - Sump location relative to ]. 22 expanding break jet 23 4. Long-term debris transport - Containment layout & sump 24 (transport to'the sump during the (or suction) locations 25 recirculation phase) - Debris physical characteristics 26 - Recirculation velocity 27 - Debris transport velocity i 28 5. Screen or sump outlet - Screen or outlet area 29 blockage effects (impairment - Water level under post-LOCA l 30 of flow and/or NPSH margin) conditions - l 31 - Recirculation flow requirements 32 - Head loss across blocked screen j 33 or outlet 34 6. Downstream blockage (effects - Core coolant channels 35 of debris deposition and - Spray nozzles ; 36 recirculation) - Pump clearances j 37 g 38 l Key elements for - Estimated amount and type of 1 39 assessment of debris that can reach sump 40 oebris effects - Predicted screen or outlet 41 blockage 42 - AP across blocked screens or
- 43 outlets 1 44 -
NPSH required vs NPSH available , 1.82/27 05/06/85 L - --. - -
. . _ . .._.; -_ s . . sc_ E _.. ~ : _
.\
I I l s, 4 i ! t , I DEBRIS SUMPS PUMPS i' !
- Types. Quentitles. and Location e Location in Plant; of Insulation
- Pump Design and Operating Redundancy Characteristics ,
, e Containment Layout and Break , Geometric Parameters
- NPSH Requiremente Ido Aisl
'I Locatione
+ Estimate Quantity of Debne *'
$'*,*P,',[e ac s. reel.
- hmp W Sucth Nng - h Generated i
i r 1 1 f I f ; e Effects of Air ingestion on t e Short-Term Trenoport by
- Hydraulic Characteristics NPSH Required a.
Blowdown Jet . Water Level Above Sump Outlet ' ' ta , p,,
* - Sump Outlet Velocity >
,
- Long-Term Transport by -Air ingestion -Inlet Design m Recirculation velocities -Inlet Loosee . Temperature Effects N
N '
@ e Effects of Particulate and ! Debrie Ingestion
- f. u I 1 f f^i e Potentist for Interceptor !
"*8'
- NPSH Required f
+ Head Lees Acrose Interceptors '
- NPSH Aveitable l
1 r , t - le There Adequate NPSH Margin _ Under All Post LOCA Conditions? ' s/ sooth! o w
, s -
o R 7 Figure A-1 Technical Consideration Relevant to ECC[S]
$ 8 Sump Performance .
4 I t
=_. - - . . _ _ _.._ _ . _ _ _ _ . . _ . _ _ _
e, ECCS SUMP DESl!N SUMP DESIGN , e commary & tocation R.doosgn 1
- F'** R"* R**u8'*d : R%n e Minimuns Water Levei e Poet LOCA Conditione e Insulation (si Used l
DESRIS CONSIDERATIONS HYDRAUUC CONSIDERA110NS ,y g g
- Air Ingestion, e of insuiadon(al Employed e Sump Outlet Conditions.
- Estimated Volume end Type P.T,Us me. of Debrie
- Minimum " ' . - Level -
- Recirculation Flow Petteme e Sump HydrouNe Lonese and Velocities in Containment e Typee e Volume of Debris Treneported
- Screen Blockage o Estimated Head Loes Acroce y, Stocked Interceptor (AHgl e, > N 1 1 P 1 I i b CORRECT DEFICIENCY
- Y'"*" I"PP"'
AHg >NPSHR? e Scale Model Data e Other Date
' I HydrouEco Yes _
C*"' N I CORRECT NPSHR DEFICIENCY l ' e Reeeeees Recirculation Requirements
- Modify interceptor No e Repiece Probism Insulation (el if d b Yee AHS No _
Corrected? ' 1 P 1 P PUMP PERFORMANCE DETERMINE NPSH PARAMETERS mp and p e Minimum Water Level Setween Sump lagestion Behavior e Screen and Rock Losses and Pump e Pump Performac.co Curvee
- Sump and Piping Loeses e Air Ingestion Effecto e Pump iniet Conditione, P,T,e,$,U, etc. - .
- Containment Conditione DEFINITIONS
, p NPSH Net Positive Suctiel Head NPSHA NPSH Available, NPSHR NPSH Required le e . Void Fraction (% by Volume)
Yee le Yee Air Present? No , P te,> 01 T - Temperature U Velocity in Pipe No , , Note:
* $ = 10 +0,50e P Calculate NPSHR should account NPSHA for line losses between f sump and the pumpe. {
i f de _ Gr en
= NpSHR7 D s e/seg pfgs e
i 8 Figure A-2. Combined Technical Considerations for Sump Performance 1.82/29 05/06/85
. . . . - - . .- . . . . ~ . . . . . . . . . ~ . ---.- ,-- . - - - - . . - . . . . . . - . ....-
4 .T 1 I \ l I I I I g Boundary of a Right a Circu!ar Cylinder
- l , Postulated Originating PipeatBreak the g
I ie I REGION I REGloN II g REGloN 111 l Total High Levels of l Dislodging in l Destruction Damage Possible l "as-febricated" 5 Materials and 5 Pieces or I Attachment Segments l l
*3 UD's% Dependent I
l 1 a l Note: 2 I 4 8UDl Pressure isobars
- l Shown Are Calculated 25 15 10 l Target Pressures for 5 l Brook Conditions of .
l 2.5 150 Bars and 35'K l g l Subcooling 2- l u l . 4-v I l \ i l i l l
! R = Radius of Circular ,
Flat Plate Target -
-1 Bar L = Distance From Break 8"
\ to Target 7 UD's ky n D = Diameter of Broken Pips l
I Patag = 0.5 poi, or Major Wall Boundary
\ \'
_lt
~l l
~/so n/n 5 Figure A-3 Multiple Region Insulation Debris Model 6 (A discussion of the model is provided in Ref 1) :
1.82/30 05/06/85
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. _ . _ _.2 g cs i
l 1 REFERENCES 2 1. U.S. Nuclear Regulatory Commission, " Containment Emergency Sump 3 Performance (Technical Findings Related to Unresolved Safety Issue 4 [WSf] A-43)," NUREG-0897, [ September-1982] Draft Revision 18, 5 June 5, 1985, awaiting publication 6 2. U.S. Nuclear Regulatory Commission, " Methodology for Evaluation of 7 Insulation Debris Effects," NUREG/CR-2791 (SAND 82-7067), September 8 1982. 9 3. U.S. Nuclear Regulatory Commission, "A Parametric Study of Contain-10 ment Emergency Sump Performance," NUREG/CR-2758 (SAND 82-0624), 11 July 1982. 12 4[6:]. U.S. Nuclear Regulatory Commission, "A Parametric Study of Contain-13 ment Emergency Sump Performance: Results of Vertical Outlet Sump 14 Tests," NUREG/CR-2759 (SAND 82-7062), [ September] October 1982. 15 5.[7:] U.S. Nuclear Regulatory Commission, " Assessment of Scale Effects 16 on Vortexing, Swirl and Inlet Losses in Large Scale Sump Models," 17 NUREG/CR-2760 (SAND 82-7063), June 1982. 18 6.[8:] U.S. Nuclear Regulatory Commission, "Results of Vortex Suppressor 19 Tests, Single Outlet Sump Tests and Miscellaneous Sensitivity Tests," 20 NUREG/CR-2761 (SAND 82-7065), September 1982. 21 7.[9:] U.S. Nuclear Regulatory Commission, " Hydraulic Performance of Pump 22 Suction Inlets for Emergency Core Cooling Systems in Boiling Water 23 Reactors," NUREG/CR-2772 (SAND 82-7064), June 1982. 24 8.[18 ] U.S. Nuclear Regulatory Commission, "An Assessment of Residual 25 Heat Removal and Containment Spray Pump Performance Under Air and 26 Debris Ingesting Conditions," NUREG/CR-2792 (CREARE TM-825), 27 September 1982. 1.82/31 07/23/85
1 r.- : i
't r
1 9.[4 ] U.S. Nuclear Regulatory Commission, " Buoyancy, Transport, and Head 2 Loss of Fibrous Reactor Insulation," NUREG/CR-2982 (SAND 82-7205), 3 [ November-1982] Revisions 1, July 1983. 4 10.[5:] U.S. Nuclear Regulatory Commission, "The Susceptibility of Fibrous 5 Insulation Pillows to Debris Formation Under Exposure to Energetic I 6 Jet Flows," NUREG/CR-3170 (SAND 83-7008), March 1983. 7 11. U.S. Nuclear Regulatory Commisssion, "Probabilistic Assessment of 8 Recirculation Sump Blockage Due to Loss-of-Coolant Accidents," 9 NUREG/CR-3394 (SAND 83-7116), July 1983, Voluna 1 & 2. 10 12. U.S. Nuclear Regulatory Commission, " Transport and Screen Blockage 11 Characteristics of Reflective Metallic Insulation Materials," 12 NUREG/CR-3616 (SAND 83-7471). January 1984. l 13 NOTE: NUREG-series documents are available from the Superintendent of 14 Documents, U.S. Government Printing Office, P.O. Box 37082, 15 Washington, D.C. 20013-7982. Information concerning placing 16 orders can be obtained by calling 202-275-2060 0.a 2171. [NRE/ . 17 6P8-Sales-Program--W:S -Naclear-Pegulatory-Eemmission--Washington-18 BE-28555:] Dates are publishing dates. l l l l l 1.82/32 07/24/85 l}}