ML19323E697
| ML19323E697 | |
| Person / Time | |
|---|---|
| Issue date: | 02/12/1976 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19323E675 | List: |
| References | |
| TASK-EM-801-4, TASK-OS NUREG-75-087, NUREG-75-087-05.4.7, NUREG-75-87, NUREG-75-87-5.4.7, SRP-05.04.07, SRP-5.04.07, NUDOCS 8005270139 | |
| Download: ML19323E697 (10) | |
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U.S, NUCLEAR REGULATORY UIMM!SSIGN DRAFT REVISION STANDARD REVBEW PLAN anam g-OFFICE OF NUCLEAR REACTOR REGULATION
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SECTICN 5.4.1 RESICUAL HEAT REMOYAL (PSR) SYSTEM REVIEW RESPONSIBILITIES Primary-ReactorSystemBranch(RSS)
Secondary - Auxiliary and Power Conversion Systems Branch (APCSB)
Containeent Systems Branch (CSB)
Core Perfomance Branch (CPB)
Electrical, Instrumentation and Control Systems Branch (EICSB)
Materials Engineering Branch (MTEB)
Mechanical Engineering Branch (MEB)
I.
AREAS OF REVIEW The residual heat removal (RHR) system is used in conjun'ction with the main steam and feed-water systees (main condenser), or the reactor core isolation cooling (RCIC) system in conjuction with the safety / relief valves in a boiling water reactor (BWR), or auxiliary feedwater svstem in conjuction with the atmospheric dump valves in a pressurized water reactor (PWR) to cool down the reactor coolant system following shutdown. Parts of the RHR' system also act to provide low pressure emergency core cooling and are reviewed as described in Standard Review Plan (SRP) 6.3.
Some parts of the RHR system also provide containment heat removal capability and are review'ed as described in SRP 6.2.2.
Both PWR's and BWR's have RHR systems which provide long term cooling once the reactor coolant temperature has been decreased by the main condenser. RCIC. or auxiliary feedwater systems. In both types of plants, the RHR is typically a low pressure system which takes over the shutdcwn cooling function when the reactor coolant system (RCS) temperature is reduced to about 300*F. Although the RHR system function is similar for the two types of plants, the system designs are different.
The RHR system in PWR's is cceposed of piping. pumps, valves. heat exchangers, monitors, and controls which take water frcm the RCS hot legs, cool it, and pump it back to the cold legs or' core flooding tank nozzles. The suction and discharge lines for the RHR pumps have apprcpriate valving to assure that the low pressure RHR system is always isolated from the RCS when the reactor coolant pressure is greater than the RHR design pressure. The heat removed in the heat exchangers is transported to the ultimate heat sink by the component cooling water or service water system. In PWR's, the RHR system is also used to fill, drain, and remove heat from the refueling canal during refueling operations; to provide ar; auxiliary pressurizer spray; and to circulate coolant through the core during. plant startup prior to RCS pump operation.
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I The RHR system in BWR's is typically composed of four subsystems. The containme,nt heat removal and low pressure eg rgency ' ore cooling subsystems are discussed in SRP 6.2.2 and c
l 6.3.
The shutdown cooling and steam condensing (via RCIC) subsystems are covered by this plan. These sutsystems make use of the same hardware. consisting of pumps, piping, heat exchangers, valves, monitors, and centrols. In the shutdown cooling mode, the BWR RHR system can also be used to suppletent spent fuel pool cooling. As in the PWR, the low pressure RNR piping is protected from high RCS pressure by isolation valves.
The steam condensing mode of RCIC operation in BWR's (when included in the plant design) provides an alternative to the main condenser or normal RCIC mode of operation during the initial cocidown. Steam from the reactor is transferred to the RHR heat exchangers where it is condensed. The condensate is piped to the suction side of the RCIC pump. The RCIC pump returns the condensate to the reactor vessel via the feedwater line. The heat removed in the heat exchangers is transporte.d to the ultimate heat sink by the service water system.
Othe'r means of removing decay heat in the event.that the RHR system is inoperable have been.
proposed for some BWR's. These approaches use some of the piping that is used for the steam condensing mode of RCIC. These approache's are also covered by this plan.
The reactor coolant temperatures and pressure must be decreased before the low pressure RHR system can be placed in operation, therefore the review of the decay heat removal function must consider all conditions from shutdown at normal reactor operating pressure and tempera-ture to the cold depressurized condition reguired for refueling. This effort is divided between the RSB and the APCSB as fol?ows:
1.
For BWR's the RSB reviews the transfer of decay heat from the reacter for the entire spectrum uf potential reactor coolant system pressures and temperatures during decay heat removal.
2.
For PWR's the APCSS reviews the transfer of decay heat from the reactor over the range of conditions from normal reactor operating temperature and pressure to the values of these parameters that permit operation of the RHR system. The RSB reviews the decay heat removal function for all lower temperatures and pressures.
3.
For both PWR's & BWR's, the APCSB reviews the component cooling or service water systems that transfer decay heat frcm the RHR system to the ultimate heat sink as described in SRP 9.2.1 and 9.2.2.
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4.
The RSS reviews the design and operating characteristics of the RHR system with respect to its shutdcwn and long term cooling function. Where the RHR system interfaces with other systems (e.g., RCIC system, ccmponent cooling water system) the effect of these systems on the RHR system is reviewed. Overpressure protection provided by the valving between the RCS and RHR system is also reviewed.
The proposed RHR system precperational and initial startup test programs are reviewed and the proposed technical specifications are evaluated in regard to limiting conditions of operation and periodic surveillance testing.
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The RHR system is reviewed to assure that it has the proper seismic and quali2y group classifications. This aspec2 of the review is performed ~ as a portion of.the effort described in SRP 3.2.1 and 3.2.2.
The RHR system is to be enclosed in a structure having the proper i
seismic classification. The review is done as a part of the effort described in SRP 3.2.2.
The RHR system is to be housed in a structure that provides adequate protection against wi,nd, tornadoes, floods, and missiles (as appropriate). The review of the adequacy of this enclosure is performed as described in other standard review plans.
l The CSS, as described in SRP 6.2.4. reviews the design of the RHR system to see that it is compatible with the function of the containment and that adequate isolation capabilities are provided.
The EICSB, as described in SRP 7.4 reviews motor-operated valve controls, interlocks, sen-sors for interlocks, position indicators, and power sources. E!CSB detennines that the interlocks on motor-operated valves used as barriers between the high and' low pressure RHR piping are suitable independent and diverse and that trip signals close the valves when the pressure is too high.
The MEB, as described in SRP '3.9.3. reviews the design and installation of the RHR system to s(,E that appilcable code requirements are met.
The MTES reviews the materials and' inservice t'nspection program for the RHR system, as described in SRP 6.1.1 and 6.6.
The CPS reviews the core decay energy outpu't on which the design is based to see that it is applicable and suitably conservative.
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The MEB and APCSB review the effects of pipe breaks both in and cutside containment on reactor shutdcwn systems. This review includes the effects of pipe whip, jet impingement forces, and any environmental conditions created. The effect of missiles on the RHR system is also reviewed by these branches.
!!. ACCEPTANCE CRITERIA The general objective of the review is to determine that the sy' stem or systems employed to re. move residual heat meets the requirements of General Design Criteria (G::C) 34 (Ref. 4) regarding residual heat removal, and GDC 19 (Ref.16) regarding operability from the control room. As noted in Section 1, the overall heat removal function must consider a wide range of potential reactor coolant temperatures _ and pressures. A portion of this range is reviewed by the APCSS for Pk'R's.
This plan deals specifically with the areas of review performed by the RSS. The acceptance criteria are discussed in the following paragraphs.
The system or systems must be capable of performing the function of transferring heat frem the reactor to the environment using enly safety grade systems. The system (s) and the system (s) enclosure must be in accordance wittr GDC 2 (Ref.1) and GCC 4 (Ref. 2), 6nd should conform to the recer.endations of Regulatory Guide 1.29 (Ref.12). Regulatory Guide 0.46 5.4.7-3 em
L (R3f.13), and the staff position: on protection against pipirg failures outside etntainment f
(Ref.15).
..j The system (s) are to satisfy the fun:tional, isolation,' pressure relief, pump protection, 4
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and test requirements specified in Branch Technical Position RSB 5-1 (Ref.11).
Interfaces between the RHR system and RCIC and component or service water systems should be designed so that operation of one does 'not interfere with, and providas proper support (where required) for the other. In relation to these and other shared systems (e.g., emer-gency core cooling and containment heat removal systems), the RHR system must conform to GDC S (Ref. 3). Component cooling ar.d service water systems removing heat from the RHR
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heat exchangers must conform to GDC 4, 45, and 46 (Refs. 5, 6, and 7). Containment isola-tion provisions for the RHR system must conform to.GDC 55, SS, and 57 (Refs. 8, 9, and 10).
i In addition to the above criteria, the acceptability of the RHR system may be based on the degree of design similarity with previously approved plants. Deviations fecm these criteria from other types of RHR systems (e.g., systems that are designed to with::tand reactor 1
coolant system operating pressure or systems located entirely inside containment) will be considered on an individual basis.
II1.
REVIEW PROCEDURES The procedures below are used during the construction permit (CP) review to assure that the design criteria and bases and the preliminary design as set forth in the preliminary safety analysis report meet the acce;tance criteria given in Section II of this plan.
i For operating license (CL) reviews, the procedures are utilized to verify that the initial design criteria and bases have been a;propriately implemented in the final design as set forth in the final safety analysis recort. The OL review a,1so includes the proposed tech-nical specifications, to assure that they are adequate in regard to limiting conditions of operation arid periodic surveillance testing.
As noted in Sections I & II, th' RSS review for PWR's is ifmited to the low pressure - low e
temperature RHR system. For SWR's, the review is to include all of the systems used to 1
transfer residual heat frem the reac:ce ovtr the entire range of potential reactor coolant
' temperatures and pressures. The following steps are to be applied by the reviewer for the 2
appropriate systems, depending on whether a PWR or SWR is being reviewed. These steps should be adapted to CP or OL reviews as appropriate.
1.
Using the description given in the applicant s safety analysis report (SAR), including component lists and perfor$ance specifications, the reviewer determines that the system (s'j piping and instruments: ion are such as to allow the system (s) to operate as intended, with or without offsi*e power and given any single active component failure.'
This is accomplished by reviewir; the' pip,ing and instrumentation diagr'ams (P& ids) to confirm that piping arrangements permit the required flow paths to be achieved and that sufficient process sensors are available to' measure and transmit required information.
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A failure modes and effec 9s analysis (or sioilar system safe 2y analysis) provided in the SAR is used to determine conformance to the single failure criterion.
I Using the comparison tables of SAR Section 1.3, the RHR system is compared to designs 2.
and capacities of such systems in similar plants to see that there are no unexplained departures from previously reviewed plants. Where possible, comparisons should be made with actual performance data from similar systems in operating plants.
3.
From the system description &nd P& ids, the reviewer determines that the isolation requirements of Branch Technical Position RSS 5-1 (Ref.11) are satisfied.
4.
The reviewer determines that the RHR system design has provisions to prevent damage to
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the RHR pumps due to the closure of the isolation valves in accordance with Branen Technical Position RSB 5-1 (Ref.11).
r 5.
Using the system process diagrams, P& ids, failure modes and effects analysis, and component performance specifications, the reviewer determines that the system (s) has the capacity to bring the reactor to cold shutdown conditions in a reasonable period of time, assuming a single failure of an active component with only either onsite or
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offsite electric power available. For the purposes of the review, 35 hours4.050926e-4 days <br />0.00972 hours <br />5.787037e-5 weeks <br />1.33175e-5 months <br /> is considered a reasonable time reriod. The reviewer cortsults with the CPB to confirm that the 2
proper core cecay energy output'was assumed for the analysis. The APCSB is responsible for the review of the initial cooldewn phase for PWR's. Therefore, this review effort 3
is to te, coordinated with that branch. For the purposes of the review of be'). PiR's and.
"s, only the operation of safety grade equipment is to be assumed.
6.
The cooldown function is to be reviewed to determine if it can be performed from the control room assuming a single failure of an active cceponent, with only either ensite or offsite electric power available. Any operations required outside of the control 3
room.s to be justified by the applicant. Life Item 5 the initial cocidown for PWR's is to be reviewed by APCSS.
7.
By reviewing the system description and the P& ids, the reviewer confirms the RHR system E
satisfies the pressure relief regtirements of Branch Technical Pesition RSB 5-1 (Ref.11).
8.
The reviewer checks the P&lDs to see that essential components of the systems eroloyed to remove residual heat are designated seismic Category I and Safety Class II (the cooling water side of heat exchangers can be Safety Class !!!). Based on statements made in SAR Section 5.'4.7 or on the reviews made by other branches the RSB reviewer confirms that the RHR system ceets the requirements of GOC 2 (Ref.1) and 4 (Ref. 2),
and conforms to the reco:rcendations of Guides 1.29 (Ref.12) and 1.46 (Ref.13) and the staff positions on piping failures outside containment.
9.
By revi, ewing the piping arrangement and system description of the RHR system, the j
reviewer confirms that the RHR system meets the requirements of GCC S (Ref 3) concerning shared systems.
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10, The RSB reviewer ccatacts the APCS 3 reviewer in conjunction with his review of the RHR g
system heat sink and refueling system interaction to interchange infomation and assure that the reviews are consistent in regard to the interfacing parameters. For example, the APCSB review determines the maximum service or component cooling water temperature.
The RSB reviewer then revi'ews the RHR system description to determine that this maximum temperature has been allowed for in the RHR system design.
11.
The RSS reviewer contacts his counterpart in the EICSB to obtain any needed infomation from their review. Specifically, EICSB confirms that automatic actuation and remote-manual valve controls are capable of performing the functions required, and that sensor and monitoring provisions are adequate. The instrumentation and controls of the RHR system are to have sufficient redundancy to satisfy the single failure criterion.
12.
The RSB engineer contacts his counterpart in CSS so that the information needed con-cerning their. reviews will be interchanged.
13.
The applicant's proposed preoperational and initial startup test programs are reviewed' to determine that they are consistent with the intent of Regulatory Guide 1.68 (Ref.14).
At the OL stage, the reviewer assu'res that sufficient information is provided by the applicant to identify the test objectives, methods of testing, and test acceptance criteria (see par. C.2.b of Regulatory Guide 1.68).
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The reviewer evaluates the proposed test programs to determine if they provide reason-able assurance that the RHR system will perform its safety function. As an alternative to this detailed evaluation, thw reviewer may compare the RHR system design to that M previously reviewed plants. If the design is essentially identical and if the prot.ed test programs are essentially the same, the reviewer may conclude that the proposed test programs are adequate for the RER system. If the RHR system differs significantly from that of previously reviewed designs, the. impact of the proposed changes on the j
required preoperational and initial startup testing programs are reviewed at the CP stage. This effort should particularly evaluate the need for any special' design features required to perform acceptable test programs.
i 14.
The proposed plant technical specifications are reviewed to:
a.
Confirm the suitability of the limiting conditions of operation, including the proposed time limits and reactor operating restrictioni for periods when system equipment is inoperable due to repairs and maintenance.
b.
Verify that the frequency and scope of periodic surveillance testing is adequate.
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15.
The reviewer confirms that the systems employed to remove residual heat are housed in a structure whose design and design criteria have been reviewed by other branches to assure that it provides adequate protection against wind, tornadoes, floods, and missilese, as appropriate.
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16.
The.RS3 reviewer provides information to other branches in those areas where tha RSB has a secondary review responsibility that is not explicitly covered in steps 1-11 above. These additicnal areas of secondary review responsibility include:
Identification of engineered safety features (ESF) and safe shutdown electrical a.
loads, and verificatico that the minimum time intervals for the connection of the ESF to the standby pcwer systems are satisfactory, b'.
Identification of vital auxiliary systems associated with the RHR system and determination of cooling load functional require =cnts and minimum time intervals.
c.
Identification of essential components associated with the main steam supply and the auxiliary feedwater system that are required to operate during and following shutdown.
IV.
EVALUATION FIN 0!NGS The reviewer verifies that the SAR contains sufficient information and his review supports the following kinds of statements and conclusions, which shculd be included in the staff's safety evaluation report for CP applications. For OL reviews, the requirements regarding single failure and operation from the control room are less stringent. The sample evalua-tion findings provided below should, therefore, be appropriately modified for OL reviews.
For PWR's "The residual hest removal function is accomplished in two phases, the initial cooldown phase and the residual heat removal (RHR) system operation phase. In the event of loss of offsite pcwer, the initial phase of cooldown is accomplished by use of the auxiliary feedwater system and the atmospheric dump valves. This equipment is used to reduca the
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reactor coolant system temperature and pressure to values that per ait operation of the RHR system. The review of the initial cooldewn phase is discussed in Section of
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the SER. The review of the RHR cperational phase is discussed belcw. The residual heat removal (RHR) system includes the piping, valves, pumps, heat exchangers, instrumenta-tion, and controls used to remove core decay heat and provide long term core cooling-following the initial phase of reactor cooldown. The scope of review of the RHR system for the plant included piping and instrumentation diagrams, equipment layout drawings, failure =cdes and effects analysis, and design performance specifications for essential.cceponents. The review has included the applicant's proposed design criteria and design bases for the RHR system and his analysis of the adequacy of those criteria and bases and the conformance of the design to these criteria and bases.
"The drawings, cceponent descriptions, design criteria, and supporting analyses associ-ated with the RER system have been reviewed and _have been found to conform to Cc: mission regulations, regulatcry guides, and staff technical positions. The RHR system has f.
been found to conform to General Cesign Criteria 2, 4, 5,19, 34, 55, 56, 57 and to Regulatory Guides 1.29, 1.46, and 1.63.
The system was found capable of performing its shutdown ccoling functions from the control recm with only cnsite electrical power or 1
offsite power available, assumirig the ecst restrictive single active compenent failure.
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v '. l IS was also found tha8 two independent and redundant barriors are always in place between the reactor coolant systems (RCS) and RHR system whenever the RCS pressure is higher than the RHR design pressure.
"The staff concludes that 'the design of the residual heat removal system confoms to the Comissicn's regulations, a'nd to applicable regulaticns, guides and staff positions, and is acceptable."
For BWR's "The residual heat removal function is acconplished in two phases, the initial cooldown phase and a low pressure-temperature operaticn phase. In the event of loss of offsite electrical power, the initial cooldown phase is accomplished using the reactor core isolation cooling (RCIC) system and the safety / relief valves. The low pressure-temperature mode of operation is usually accomplished by the residual heat removal (RHR) system.
However, certain single failures can render the RHR system inoperative. In that event, two alternate systems that use components of the RCIC and RHR system are available to bring the reactor to cold shutdown conditions.
"The systems employed to transfer residual heat from the reactor include the piping, valves, pumps, heat exchangers, instrumentation, and controls. The scope of review of
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these systems for the plant included piping and instrumentation diagra=s, equip-ment laycut drawings, failure mode and effects analysis, and design performance specifi.-
cations for essential ecmponents. The review has included the applicant's preposed design criteria and design bases for these systems and his analysis of the adequacy of those criteria and bases and of the conformance of the design to these criteria and
- bases, "The drawings, component descriptions, design criteria, and supporting analyses q
associated with the' systems employed to recove residual heat from the reactor have been reviewed and have been found to conform to Comnission regulations, regulatory guides, and staff technical positions. These systems have been found to conform to General Design Criteria 2, 4, 5, 19, 34, 55, 56, 57 and to Regulatory Guides 1.29, 1.46 and 1.68. The system was found capable of performing its shutdown cooling functions from the control room with only onsite electrical pcwer or offsite power available, assuming ll the most restrictive single active component failure. It was also found that two independent and redundant barriers are always in pl=.cr between the RCS and RHR system whenever the RC3 pressure is higher than the RHR det yn pressure.
"The staff concludes that the design of the systems employed to remove residual heat from the reactor conform to the C:=tssion's regulations and to applicable regulatory guides and staff technical positiens, and is acceptable."
' V.
REFERE.'CES 1.
10 CFR Part 50, Appendix A, General Cesign Criterion 2, " Design Bases for Protecticn
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Against Matural phencmena."
e 5.4.7-8 i
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10 CFR Part 50, Appendix A, General Design Criterion 4. " Environmental and Missile i
l 2,
l Design Bases."
10 CFR Part 50, Appendix A. General Design Criterion 5, " Sharing of Structures, Systems, 3.
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and Components."
10 CFR Part 50, Appendix A General Cesign Criterion 34, " Residual Heat Removal."
I 4.
l 10 CFR Part 50, Appendix A, General Cetign Criterion 44, " Cooling Water."
5.
10 CFR Part 50, Appendix A. General Design Criterion 45, " Inspection of Cooling Water s
6.
l System."
10 CFR Part 50 Appendix A, General Cesign Criterion 46, " Testing of Cooling Water 7.
System."
10 CFR Part 50, Appendix A, General Design Criterion 55, " Reactor Coolant Pressure 8,
Boundary Penetrating Contairment."
10 CFR Part 50, Appendix A, General Design Criterion 56, " Primary Containment Isolation."
9.
10.
10 CFR Part 50, Appendix A, General Design Criterion 57, " Closed System Isolation valves."
11.
Branch Technical Position RSS 5-1, " Design Requirements of the Residual Heat Removal l
System," attached to SRP 5.4.7.
12.
Regulatory Guide 1.29, " Seismic Design Classification," Revision 1.
13.
Regulatory Guide 1.46, " Protection Against Pipe Whip Inside Containment."
14 Regulatory Guide No.1.68, "Preoperational and Initial Startup Test Progra=s for Water-Cooled Power Reactors."
15.
Branch Technical Positions APCSS 3-1, " Protection Against Postulated Piping Failures in Fluid Systems Outside Contairment " attached to SRP 3.6.1, and MES 3-1, " Postulated Break and Leakage Locations in Fluid System Piping Outside Contairment," atta?hrj to SRP 3.6.2.
16.
10 CFR Part 50, A;pendix A, General Cesign Criterion 19, " Control Room."
e 5.4.7-9