Text

Post-LOCA Boron Concentration Mgt for CR-3
	ML20217G699
Person / Time
Site:	Crystal River
Issue date:	04/06/1998
From:	Page D, Wisinger G; FRAMATOME
To:	;
Shared Package
ML20217G681	List: 3F0498-17, Submits Addl Info Clarifying post-LOCA Boron Precipitation Plan to Facilitate NRC Review of LAR 223,dtd 980227. Calculation 86-1266272-02, Post-LOCA Boron Concentration Mgt for CR-3, Encl; ML20217G699;
References
	86-1266272-02, 86-1266272-2, NUDOCS 9804290190
	Download: ML20217G699 (66)
	v • d • e

{{#Wiki_filter:FLORIDA POWER CORPORATION CRYSTAL RIVER UNIT 3 DOCKET NO. 50-302/ LICENSE NO. DPR-72 ) i i ATTACHMENT B i FPC CALCULATION M97-0146, REVISION 2, WITH SUPPORTING FRAMATOME TECHNOLOGIES INC. DOCUMENT 86-1266272-02 gg42;ggggggggjo2 p PDR

eNs C* N Florida INTEROFFICE CORRESPONDENCE 4::61 Po...w.u;.'r

- - =

co Nuclear Engineering NT02 240-1660 Office MAC Telephone

SUBJECT:

Crystal River Unit 3 Quality Record Transmittal-Analysis / Calculation To: Records Management - NR2A The following analysis / calculation package is submitted as the QA Record copy: DOCNO (FPC DOCUMENT IDENTIFICATION NUM 809 REv. SYSTEM (S) TOT AL PAGES TRANSMITTED M 97-0146 2 DH,RC 4/, TITLE Post-LOCA Boron Concentration Management for CR-3 KWDS (IDENTIFY KEYWORDS FoR LATER RETREVAL) hot leg injection,, decay heat cirop line, auxiliary pressurizer spray, precipitation, sump sampling 1 DXREF (REFUeCES OR ALES UST mfM ARY RLE FIRST} 88.1 ?RR777 n7 FTl 481744 VEND (VENDOR NAME) VENDOR DOCUMENT NUMBER (DXREF) SUPERSEDED DOCUMENTS (!EREF) FTl 86-1266272-02 M97-0146 Rev 1 lN/A l l l l l l l l N/A ll l l COMMENTS (USAGE RESTRCTIONS. MOPaET ARY, ETC ) NOTE: Use Tag number only for valid tag numbers (i.e., RCV-8, SWV-34, DCH-99); otherwise, use Part number field (i.e., CSC14599, AC1469). If more space is required, wnte "See Attachment" and list on separate sheet.

FOR RECORDS M ANAGEMENT USE ONLY *
Quality Record Transmittal received and information entered into SEEK.

Entered by: Date (Return copy of Quahty Record Transmittal to NOE Support Specialist.) DESIGN ENGINEER DATE VERFicATION ENGINEIR CATE SUPEFMSOR, NUCLEAR ENG DATE Yk_ h A NA2/ff h ~~/59hf 4-y cc: Nuclear Projects (If MAR /CGWR/PEERE Celculation Review form Part 111 actions required Yes ' No Return to Service Related) O Yes b No (If Yes, send copy of the form to Nuclear Regulatory Assurance and a Supervisor, Config. Mgt. Info. copy of the Calculation to the Responsible Organization (s) identified in Mgr., Nucl. Operations Eng. (Original) w/ attach Part l!! on the Calculation Review form.) h 12/s7

sm h j M........... ANALYSIS / CALCULATION

SUMMARY

I q A.c.suu.rRM O!SCIPUNE CONTROL NO. REVISION LEVEL DOCUMENT IDENTIFICATION NUMBER M 97-0146 2 l l TITLE Post-LOCA Boron Concentration Management for CR-3 CLAS$1FICAT10N (CHECK ONE) @ safety Related O Non safetv noi.t d. MARf5P/CGWR/PEERE N0MBER N/A VENDOR COCUMENT NUMBER 86-1266272 02 APPROVAL PRINTED ,, SIGNATURES NAME Design Engineer 8h h gg, Q://, V. M. Esquillo { Date Q [1 [q? Verification Enginger N/A N/A Date Supervisor R. W. Knoll Date t{/t.1/W ITEMS REVISED This revision completely replaces Revision 1. This revision adds Auxiliary Pressurizer Spray (APS) matchup times when both LPI pumps are available. In this instance the B-LPl pump will provide suction to one HPl pump and inject the remaining flow into the downcomer through DHV-6. The A-LPI pump will be used to provide spray flow and HPl flow (600 GPM) only as LPI flow into the downcomer is isolated via closure of DHV-5. This arrangement maximizes the APS flow. This revision incorporates all comments generated by FPC during the review of the FTl document. PURPOSE

SUMMARY

The purpose of this calculation is to document the post-LOCA boron management strategy for CR-3. The methods used to develop this strategy were developed by FTI. Three active methods are available for ensuring that the boric acid solubility limits are not challenged. The first involves opening the decay heat drop line (DHDL) to the sump; the second is to refill the RCS via Auxiliary Spray, and the third is Hot Leg injection via reverse flow through the DH piping. The third option is pending NRC review and approval. RESULTS

SUMMARY

The outcome of the effort consists of Technical Support Center guidance for post-LOCA boron concentration management. The guidance is based on inferring the core boron concentration from the measured sump concentration. The premise is that if boron is being depleted in the sump, it must be concentrating in the RCS or core. The Figures and Tables described in the document provide the means to determine when precipitation control is necessary, and what active means is appropriate. I l Rev. 3/97

( ,,c~m (d)N CALCULATION REVIEW cAcc.arv.rau Page 1 of 2 CALCULATION N0JREV. M 97-0146 / Revision 2 PART I - DESIGN ASSUMPTION / INPUT REVIEW: APPLICABLE @ Yes O No The following organizations have reviewed and concur with the design assumptions and inputs identified for this calculation: Nuclear Plant Technical Support g.4/. uuS Q$ f$ s~ System Engr s.gn.iw'.m.t. j Nuclear Plant Operations lON OTHERISI Sigmtwecm b2. - pfG&(CkL 4 A 4'6 E.M MoMA SegnatweSate ' Signatws/Date PART ll - RESULTS REVIEW: APPLICABLE @ Yes O No The following organizations have reviewed and concur with the results of this calculation and understand the actions which the organizations must take to implement the results. Nuclear Plant Technical Support j h System Engr SS"'*'S" f Nuclear Plant Operations Signatwe/Date (,,/ Nuclear Plant Maintenance 8"'***" O Yes @ N/A l Nuclear Licensed Operator Training S'8"* * *

O ves g N/A Manager, Site Nuclear Services SS"*
O Yes

@ N/A i Sr. Radiation Protection Engineer S"*'****" O Yes @ N/A Yes N/A I .N d' ..g_.._ y OTHER: b6 - W.AW \\CA4 fl{. 4f4 @f 6.l4. N O Signatwe/Date Rev.12/97 I

,m,, (g' Poy.e.r CALCULATION REVIEW l l Page 2 of 2 l CALCul.ATioN NoJREV.

97-b N a & y 2 PART lli - CONFIGURATION CONTROL: APPLICABLE U Yes No The following is a list of Plant procedures / lesson plans /other documents and Nuclear Engineering calculations which require updating based on calculation results review:

Document Date Reauired Resoonsible Oraanization Upon completion, forward a copy to the Manager, Nuclear Regulatory Assurance Group for tracking of actions if any items are identified in Part 111. If calculations are listed, a copy shall be sent to the original file and the calculation log updated to reflect this impact. PART IV - NUCLEAR ENGINEERING DOCUMENTATION REVIEW The responsible Design Engineer must thoroughly review the below listed documents to assess if the calculation requires revision to these documents, if "Yes," the change authorizations must be listed l below and issued concurrently with the calculation. Enhanced Desian Basis Document O Yes b No") Vendor Qualification PackaaeO Yes No voa) I FSAR Yes No "'"*) Toolcal Desion Basis Doc. Yes No U") E/SOPM O Yes B No I") Imoroved Tech. soecification Yes Nopt.w) Imoroved Tech. Soec. Bases Yes NoMt **) Other Documents reviewed: Confio. Momt. Info. System Yes NoSo") O Yes O No iCHANGE coC. emNCC Analysis Basis Document Yes No [Yes No ges) (CHANGE DOC REFERENCQ Desicn Basis Document Yes b No ") O Yes O No I (CHANGE DOC. REFERENCQ Apoendix R Rre Study 0Yes No ") Oyes No I (CMANGE DOC. REFER &4CQ Are Hazardous Analysis Oyes' U No ") YesONo (CHANGE DOC. REFERENCS FC#) NFPA Code Conformance Document Yes No Yes No (CxANGE ooe. REFEneNCo PART V - PLANT REVIEWS / APPROVALS FOR INSTRUMENT SETPOINT CHANGE PRC/DNPO approval is required if a setpoint is to be physically changed in the plant through the NEP 213 process. PRC Review Required C Yes b No PRC Chairman /Date DNPO Review Required C Yes No DNPO /Date DE3aN ENGINEERIDATE DE3GN ENGINEER. PRINTED NAME &f&f A gY W y Rev.12/97

R 20697-3(12/95) [ ami CALCULATIONAL

SUMMARY

SHEET (CSS) f!MYMR,ME 86-1266272-02 DocuMENTIDENTL lER TITLE Post-LOCA Boron Concentration Management for CR-3 PREPARED BY: REvlEWED BY: NAME G J Wisinger NAME D R Page s1GNATuRE gp 7 _ _x slGNATuR O - EngineerIV \\ TITLE D ff MLE Engineer I TATE g/gg Cost CENTER 41010 REF. PAGE(s) 7 TM STATEMENT: REVIEWER INDEPENDENCE PURPOSE AND

SUMMARY

oF REsuLTs: l This report summarizes boron concentration control methods and calculations needed for the CR-3 plant to mest NRC requirements for post-LOCA boron concentration control. Specifically, the active boron dilution mtthods available at CR-3 were summarized, calculations to demonstrate compliance to Criterion 5 of 10 CFR 50.46 w:re provided, post-LOCA boron concentration control guidance suitable for Technical Support Center uss was defined, and the time ranges over which changes in the sump boron concentration will be observed following initiation of an active dilution method were quantified. The compliance calculations demonstrated that CR-3 can meet Criterion 5 of 10 CFR 50.46 by having at least ons active dilution method that can be initiated prior to reaching the solubility limit when a decay heat of 1.2 tim:s ANS 1971 was used. These calculations used revised core mixing volumes to define limiting times without credit for RWV overflow or gap flow. The DL RB-sump method was shown to be effective at lower RCS prcssurcs, but the method cannot be used at higher RCS pressures because of potential sump screen damage. Tha flow rate that can be provided via APS limits the time post-trip that it is effective, but it has been shown to be ad:quate to cover the pressures above which the DL RB-sump method can be used. Considered together, et I:ast one of the methods can be effectively established prior to the core reaching the solubility limit. This combinition of methods meets the requirement to have an active boron dilution mechanism that is effective over any RCS pressure range that core boron dilution could be needed. Ths TSC guidance includes a method for determining when and what' form of active 5oron dilution can be used ~ bastd on RB mixed-mean to sump boronometer measurements, RCS saturation temperature from the aver of thm core exit thermocouples, and time post-LOCA. The preferred dilution method is via APS, because this mLthod does not require an LPI pump to be shutdown. The guidance is comprehensive in that it provides information for use with and without sump boronometer indications. in the event that the boronorneter is unavailable, time and saturation temperature can be used to initiate active boron dilution methods. i THE FoLLoWING COMPUTER codes HAVE BEEN usED IN THis DOCUMENT: CoDEIvERsloN / REV CoDEIvERsloN / REV THis DOCUMENT CONTAINs Assumptions THAT MusT BE VERIFIED prior To usE oN SAFETY RELATED WORK YEs ( ) No ( x) l PAGE 1 OF 60

Framatome Technologies Inc.. 86-1266272-02 l Summary of Results l I Post-LOCA Boron Concentration l Management for CR-3 l l l Florida Power Corporation Crystal River Unit 3 \\ l FTl Document 86-1266272-02 April,1998 f 2 l

4 Framatomo Technologics Inc.. 86-1266272-02 Record of Revision l Rev.No. Chance Sect / Para Descriotion/Chanae Authorization 00 initial release, December 1997. 01 All New CR-3 boron concentration calculations with revised boundary conditions, non-uniform sump boron concentration gradients, sump transport delay times, and boronometer l indication delay times. February 1998. l 02 Changes identified by Add APS matchup times when both LPI pumps i revision bars on pages are available and DHV-5 is isolated. 5,7,12,13,15,16,23, l 24,26,31,34,37,41, l 47, & 51 I 3

1 1 FramatOme TechnOIOgics Inc.. 86-1266272-02 i Table of Contents l List of Ta b l e s.............................................................. List o f Fig u re s............................................................ List of R e fe re n ce s......................................... t ...................................7 1. ABSTRACT.........................................................................................................8 2. ACTIVE BORON DILUTION METHODS............................................................. 9 l 2.1 DECAY HEAT DROP LINE DUMP TO SUMP (DL RB-SUMP).............. .......................10 2.2 PRESSURIZER AUXILIARY SPRAY FLOW FROM THE LPI PUMP (APS)...... .....12 2.3 HOT LEG INJECTION (HLI) VIA REVERSE FLOW THROUGH THE DHDL......... .............13 3. S U M M A RY O F M ETH O D S.............................................. 3.1 LI ST O F KEY ASS UMPTION S......................................

3. 2 S U MMARY O F l N P UTS..........................................

3. 3 AD DITIONAL CONSIDERATIONS........................................

4. COMPLIANCE WITH 10 CFR 50.46 REQUIREMENTS.................................... 36 5. EOP GUIDANCE FOR POST-LOCA BORON DILUTION................................ 40 5.1 MINIMUM TIMES FOR ACTIVE BORON DILUTION WITHOUT SUMP BORON SA 5.2 S UM P B ORON CONCENTRATIO N M ETHOD........................................

5. 3 TS C G U ! DAN C E.................................................

5.4 DEMONSTRATION OF BORON DILUTION METHODS....................................... 6. CONFIRMATION OF BORON DILUTION VIA SUMP CONCENTRATIO M E A S U R E M E N T S............................. ......... 57 7. S U M M A RY A N D C ON C LU Sl O N S............................................................. r I e 4 I

Framatomo Technologics Inc 86-1266272-02 List of Tables Table 1. APS Flow Rates and Time to Fill the Pressurizer................................... Table 2. APS Matchup Times for B-LPl Pump Operation.............................................15 Table 3. APS Matchup Times for A-LPI Pump Operation.............................................16 Table 3.1. APS Matchup Times for A-LPI Pump With DHV-5 Isolated.........................16 Table 4. Key input Parameters for the Boron Precipitation Analyses........................... 31 Table 5. LPI Flow Rates with Suction from the BWST............................................ Table 6. Approximate CR-3 CLPD' HPI Flows to the Core........................................... 33 Table 7. CR-3 Auxiliary Pressurizer Spray Flow Rates................................................ 34 Table 8. Minimum Solubility Time vs RCS Saturation Temperature and Pressure with 1.2 AN S 1971 Decay Heat................................................................... 3 8 Table 9. Minimum Solubility Time vs RCS S'aturation Temperture ahd Pressure with 1.0 ANS 1971 Decay Heat................................................................... 50 l 5

Framatome Technologins Inc.. 86-1266272-02 List of Figures Figure 1. CR-3 DHDL Dump to Sump Flow Paths with the A-LPI Pump...................17 Figure 2. CR-3 DHDL Dump to Sump Flow Paths with the B-LPI Pump..................18 Figure 3. CR-3 Pressurizer Auxiliary Spray Flow Paths v'ith the A-LPI Pump............19 Figure 4. OR-3 Pressurizer Auxiliary Spray Flow Paths with the B-LPl Pump............ 20 Figure 5. CR-3 DHDL Hot Leg injection Flow Paths with the A-LPI Pump................. 21 Figure 6. CR-3 DHDL Hot Leg injection Flow Paths with the B-LPI Pump................ 22 Figure 7. APS Effective Boron Dilution Time Without Gap Flow............................. 23 Figure 8. APS Effective Boron Dilution Time Without Gap Flow............................. 24 Figure 9. Core. Mixing Volume Versus Time at 2568 MWt and 1.2 ANS 1971............. 35 Figure 10. Core Mixing Volume Versus Time at 2568 MWt and 1.0 ANS 1971.......... 35 Figure 11. 2568 MWt Matchup Times and Times to Solubility without Gap Flow or Active Boron Dilution with 1.2 ANS 1971 Decay Heat......................... 39 Figure 12. Matchup Times and Temperatures for Active Boron Concentration Control (2568 MWt with 1.0 ANS 1971).................................................. 51 Figure 13. Core Boron Concentration Control Limits................................................ 52 Figure 14. Minimum Boron Solubility and Mixing Limit Time versus RCS S a tu ra tio n Tem perat u re.................................................................. Figure 15. Demonstration of Boron Dilution with DL RB-Sump Flow........................ 54 Figure 16. Demonstration of Boron Dilution with APS Flow...............................55 Figure 17. Demonstration of Boron Dilution with HLI Flow.................................. 56 I I 6 l

i Framatoms Technologias Inc.. 86-1266272-02 1 ' List of References 1.

FPC Calculation S96-0134, Rev.1, " Fluid Velocity Analysis for the Reactor Building Sump Screens."

2.

FPC Calculation M97-0097, Rev.1, " Low Pressure Auxiliary Spray Flow Rate for Boron Precipitation."

3.

interoffice Correspondence, S. K. Balliet to K. R. Campbeil #NOE97-2696 dated 12/23/97.

4. FTl Document 32-1266221-01, "DHDL R5 Analyses for Boron Dilution," 12/97. 5. FTl Document 32-1266263-00, " Sump Delta Method for CR-3," 12/97. 6. FTl Document 32-1266263-01, " Sump Delta Method for CR-3," 2/98. 7. FTl Document 32-1266110-00, "B&WOG Post-LOCA Core Boron Dilution," 4/17/97. 8. FTl Document 32-1266110-01, "B&WOG Post-LOCA Core Boron Dilution." 9. FTl Document 32-1266110-02, "B&WOG Post-LOCA Core Boron Dilution."

10. FTl Document 51-5000519-03,

Boron Dilution by Hot Leg injection," 12/97.

11. FTl Document 51-5000519-06, " Boron Dilution by Hot Leg injection," 2/98.

12. FTl Document 32-1266312-00,." Characterization of Boronometer Extracted Sample."

13. *FPC Calculation M95-0044, Rev. O, "RW/DC/DH Thermal Analysis - DC System Temperature Calc."

14. FTl Document 32-1266137-02, "CR-3 Containment Analysis for SBLOCA."

15. *FPC Calculation M98-0005, Rev. O, "DHHE Outlet Temperature Sensitivity Study."

l

16. FTl Calculation 32-1269013-02, " Fluid to Wall Heat Transfer in A Pipe for CR-3 Decay Heat Drop Line."

17. FTl Document 32-1266221-00, "DHDL R5 Analyses for Boron Dilution," 12/97.

~ 18.' 'FPC Calculation CSM98-0003, Rev. O, " Case Study for M-97-0097, Auxilia y Pressurize Spray Flow."

19. FTl Document 32-1266110-03, "B&WOG Post-LOCA Core Boron Dilution."

" These documents are maintained and contro"ed by Florida Power Corporation. Per FTl procedures, use of ~ these references are allowed in safety-grade calculations with the approval of the cognizant unit manager or contract manager. The signature below use of these documen to this evaluation. (Uriit Manager / Contract Manager) '(Da'te) 7

r i Framatome Technologies Inc.. 86-1266272-02

1. Abstract l

Post-LOCA boron concentration control is an issue being reviewed by the Nuclear Regulatory Commission (NRC) for Crystal River Unit 3 (CR-3). Florida Power Corporation (FPC) is committed to provide calculations to support license amendment request (LAR) #223, which describes their approach to boron concentration control. Framatome Technologies incorporated (FTI) has performed and recorded the required analyses in verified documents. This report summarizes the results of those ) calculations in a form that CR-3 can include in their records system to meet the commitment to the NRC. It describes the active boron dilution methods available a CR-3, provides calculations to dernonstrate compliance with Criterion 5 of 10 CFR 50.46, gives post-LOCA boron concentration control guidance suitable for Technical Support Center (TSC) use, and identifies the time ranges over which changes in the sump boron concentration will be observed following initiation of an active dilution method. The compliance calculations demonstrate the effectiveness of the auxiliary pressurizer spray (APS), the drop line to the reactor building (RB) sump (DL RB-Sump), and hot leg injection (HLI) via reverse flow through the decay heat drop line (DHDL) as active boron concentration control mechanisms. The calculations demonstrate th least one of these means will be effective in diluting the core boron for any loss-of-coolant accident (LOCA) scenario prior to the core boron concentration reaching the solubility limit. These results are based on conservative calculations that assume 1.2 times the American Nuclear Society (ANS) 1971 standard fission product decay heat to show compliance with 10 CFR 50.46 criteria for long term core cooling. The information developed for TSC guidance uses 1.0 times the ANS 1971 values for core decay heat to define operator actions necessary for post-accident boron concentration control management strategies. 8

Framatoms Technologics Inc. 86-1266272-02

2. Active Boron Dilution Methods Criterion 5 of 10 CFR 50.46 requires that following a LOCA, long-term core cooling-must be assured. The Emergency Core Cooling System (ECCS) is designed to refill the core and provide continuous makeup to account for the decay heat boiloff rate for the duration of the event. Pumped ECCS injection is provided initially from the borated water storage tank (BWST) and later by recirculation from the RB sump. The post-LOCA core boiling will concentrate boron in the core. Precipitation could occur if the core boric acid concentration exceeds the solubility limit for the RCS conditions (specifically saturation temperature) resulting in the potential for blockage'of the core cooling channels. This presents a potential challenge to long term cooling. Post-LOCA core boron concentration control can be provided by any active or passive mechanism that results in a net liquid flow through the core.

The passive mechanisms available for core boron dilution are reactor vessel vent valve (RVW) liquid overflow, hot leg nozzle gap liquid recirculation, loop refill, and boron carryover in steam. The active methods are initiated and controlled by operator actions. The CR-3 active dilution methods include:

1. Decay heat drop line dump to sump (DL RB-sump),

2. Auxiliary pressurizer spray (APS) flow via the low pressure injection (LPI) pump, and

3. Hot leg injection (HLI) via reverse flow through the decay heat drop line.

The plant configuration required for use of each method and the equipment availability needed for each is described in the following sections. 9

Framatomo Technologics Inc. 86-1266272-02 2.1 Decay Heat Droo Line Dumo to Sumo (DL RB-Sumo) The decay heat drop line (DHDL) is attached to the Loop B (loop without pressurizer). hot leg piping at the bottom of the first elbow downstream of the reactor vessel. This line provides a direct flow path from the hot leg to the RB sump. The flow out of the hot leg carries highly borated liquid from the core region to the sump. This flow is replenished by dilute downcomer liquid, which has boration levels similar to those of the sump. The LPI / HPI flushing of emergency core cooling system (ECCS) water into the downcomer and out of the break during the long term cooling phase of the LOCA keeps the downcomer and sump boron concentrations approximately equal. Use of the DL' RB-sump method requires one of the two LPI pumps to be taken off-line and the valves in the DHDL to be configured such that the ' reactor coolant system (RCS) liquid can flow . from the hot leg into the decay heat drop line, backward through the non-operating LPI pump suction line into the sump. This dilution method is currently available at CR-3 via i the piping configuration and flow paths shown in Figure 1 and Figure 2. Use of the DL RB-sump method is restricted to RCS-to-sump pressure differences that will not allow the liquid velocities through the LPI intake line to exceed the hydraulic loading limits calculated for the sump screens. Protection of the sump screens is important because they prevent debris in the RB from entering the sump and being entrained into an operating ECCS pump. The analyzed liquid velocity limit that protects the integrity of the sump screen is 30.5 ft/s (Ref.1). A RELAP5 analysis performed by j FTl determined that DHV-42 or DHV-43 could be partially opened to an equivalent area { of not more than 2.56 in at hot leg pressures of 73 psia or below (Ref. 4) without exceeding the velocity limit of 30.5 ft/s. This analysis credited cooling of the liquid as it traversed the hot leg piping. There are two methods available for determining the hot leg pressure. There is a pressure tap located in the vertical pipe of the hot leg that directly reads the RCS 10

i l Framatoma Technologi::s inc, 86-1266272-02 i pressure. This pressure tap has an instrument uncertainty that is too large to be used I 4 to determine when the DHDL could be opened. There are also sixteen qualified incore i .thermocouples that can be read from the plant computer. An average of these readings will allow the operators to determine the core exit temperature, and since the system is saturated, the RCS pressure is thereby known. An average of a minimum of fourteen incore thermocouples, using the plant computer, results in an uncertainty band of +9.0/- 19.3 F of indicated minus actual temperature (Ref. 3). The saturation temperature at 73 psia is 305.77 F. The indicated average temperature at which the drop line should be opened is 305.77 - 19.3 = 286.47 F or a saturated pressure of 54 psia. If the DHDL is opened at this temperature, the actual conditions could be as low as 286.52 - 9 = 277.52 F, which corresponds to a minimum pressure of 47 psia. Therefore, the DHDL ~~ can be opened when the average of fourteen exitihermocouples.is at or below 286 F (indicated RCS pressure of 54 psia) to ensure that the hot leg pressure is actually below 73 psia. initiation of the dump-to-sump flow will result in flashing of the RCS liquid as it flows through the throttled dropline valve (DHV-42 or DHV-43). The steam that flows into the sump should not be drawn into the intake of the operating LPI pump suction piping because it could cause cavitation and adversely affect pump operation. The onset of potential adverse behavior could begin anytime between 2 minutes and 3 hours after the last valve is opened. This time period is the DHDL travel time for the saturated liquid in the hot leg to reach the sump (Ref. 8). For this reason, the operator should continuously monitor the operating LPI pump motor current for indication of cavitation once the DL RB-sump method is initiated. If unusual behavior is detected, flow through the DHDL she>uld be isolated immediately to protect the operating LPI pump. (A different dilution method should be used if available, if not, reactivation of this method l when the differential pressure between the RCS and the RB is less could be more successful.) ~ _ l 11

i l l Frematomo Technologi::s Inc. 86-1266272-02 l 2.2 Pressurizer Auxiliarv Sorav Flow from the LPI Pumo (APS) J l The APS dilution method is also available at CR-3. With APS, alignment of the ECCS piping to provide flow from the LPI pump to the APS nozzle provides a mechanism for core boron dilution. The piping arrangements and flow paths for flow with a single LPI pump available (one lost to single failure) are shown in Figure 3 and Figure 4. This alignment does not require termination of an LPI pump, but it may necessitate throttling of the LPI flow into the RCS to generate higher auxiliary spray flow rates. The piping arrangement and flow paths for flow with both LPI pumps available are also shown in Figure 3. In this alignment, the B-LPI pump will provide suction to one HPl pump and inject the remaining flow into the downcomer through DHV-6. The A-LPI pump will be used to provide spray flow and HPl flow (6'00 gpm) only. LPI flow into the downcomer l from this train will be isolated via closure of DHV-5. This arrangement maximizes the APS flow. After the spray fills the pressurizer it begins to flow into the hot leg and finally to the j core region. If the spray flow exceeds the core boiloff rate, the excess flow will raise the level in the hot leg and upper plenum. The static head difference bety.ce the downcomer and core regions will not support the higher level in the upper plenum. As a result, a small net reverse liquid flow from the core-mixing region into the lower plenum and back up the downcomer will be established. This reverse flow will provide core boron concentration control when the boron outflow exceeds the boron inflow from the pressurizer spray. The core boiloff concentrates any boron in the spray. When the i excess spray flow carries out more boron than is concentrated in the core, a long-term dilution mechanism is achieved. The minimum available spray flows as a function of RCS pressure (Ref. 2 and 18) are shown in Table 1 along with the pressurizer fill time. These flows consider throttled LPI flow with a resulting actual ECCS flow split of 600 gpm HPl and 1600 gpm LPl. FTl 12 L

Framatomo Technologics Inc. 86-1266272-02 used these flows to calculate the time at which the pressurizer auxiliary spray flow matches decay heat and the time at which it provides excess flow (6 gpm) such that boron dilution is achieved (Ref. 8 and 19). Table 2 provides the decay heat matchup ' times and effective boron dilution times for spray flow provided by the B-LPI pump considering both 1.0 and 1.2 times ANS 1971 decay heat. Table 3 provides the same information for spray flow provided by the A-LPI pump. Table 3.1 provides the same ~ l information for spray flow and 600 gpm of HPI flow provided by the A-LPI pump with ) LPI and additional HPI provided by the B-LPl. pump. This information is presented graphically in Figure 7 and Figure 8. These results are appropriate once the t l pressurizer has filled and are valid for a quasi-steady RCS pressure without hot leg nozzle gap flow. If the nozzle gaps are open and liquid is flowing, the gaps can directly i bypass some portion of the spray flow. However, if the gap flow is sufficient to bypass l a significant fraction of the spray flow, pressurizer auxiliary spray flow dilution is not needed because the gaps will be providing adequate boron dilution. Once the APS flow alignment is established, flow can be verified by the pressurizer level increase. Indication that the APS is providing core boron dilution may be obtained via the sump boron concentration measurement described in Section 5. l 2.3 Hot leo Iniection (HLI) Via Reverse Flow Throuah the DHDL The DHDL can also be used to inject liquid into the hot leg to initiate a net core reverse flow with discharge through the cold leg pump discharge (CLPD) break. This process is similar to hot leg injection via APS except that much higher flow rates can be achieved. In order to establish HLI, one LPI pump must be out of service, the LPI cross-connect line must be opened and have a. qualified flow ir:dication, the operator must throttle the normal LPI flow to the core flood, tank (CFT) nozzle, and the decay heat drop line valves must be opened to the RCS. Flow is reversed through the idle LPI pump. This method is currently available for CR-3. (The application of this method at CR-3 will be reviewed by the NRC under a separate submittal. The method is presented in this 13

l Framatome Technologics inc. 86-1266272-02 document only for completeness, and adequately describes the mechanics and principles behind the method.) The piping arrangements and flow paths for CR-3 are shown in Figure 5 and Figure 6. FTl has performed calculations to demonstrate boron concentration control with reverse DHDL hot leg injection while assuring adequate core cooling (Ref.11). The results indicate that the hot leg injection alignment must provide flow for one HPl pump (up to 600 gpm), a minimum hot leg injection flow of at least 500 gpm, and approximately 1000 gpm flow through one CFT nozzli. The flow splits demonstrate the capability of hot leg injection to match decay heat and initiate a net reverse core flow to mitigate the boron concentration buildup at RCS pressures of 72 psia (the maximum pressure in which the core concentration could reach the solubility limit) or below and any time after five hours. The required LPI flow considers all significant measurement and instrument uncertainties. The drawback of this method is that it requires one LPI pump to be deactivated, and the method must be initiated prior to exceeding the hot leg mixing limit described in Section

5. The required ECCS flow alignment is such that the flow from the lone operating 'LPI pump must provide flow to an HPI pump and the remaining flow is split between the one core flood line or LPI nozzle and the DHDL. The operator must throttle valves in the ECCS system to provide the targeted flow splits necessary to ensure adequate core cooling and provide adequate boron dilution via reverse flow through the DHDL.

14

~ Framatoma Technologins Inc.. 86-1266272-02 Table 1. APS Flow Rates and Time to Fill the Pressurizer. B-LPI Spray Flow A-LPI Spray Flow A-LPi Spray Flow w/ (Note 1) (Note 1) DHV-5 Isolated (Note 2) Pressure Flow Rate Fill Time Flow Rate FillTime Flow Rate Fill Time (psia) (gpm) (br) (gpm) (hr) (gpm) (hr) 14.7 114.5 1.73 125.5 1.57 135.6 1.46 '35 102.8 1.92 114.7 1.72 125.8 1.57 45 97.0 2.04 109.4 1.81 120.9 1.63 60 86.4 2.29 100.1 1.97 112.6 1.76 75 75.8 2.61 90.7 2.18 104.2 1.90 105 46.3 4.27 67.3 2.94 84.3 2.34 Note 1: These flows were calculated with throttled LPl flows and the assumed flow splits of 600 gpm HP and 1600 gpm LPI flow from either the A-and B-LPI pumps. This maximum flow (1600 gpm) is assured by throttling the LPI flow to an indicated flow of 1100 to 1300 gpm. Note 2: These flows were calculated with the LPI cross-connect (DHV-7 & -8) closed, A-LPI (DHV-5) closed and 600 gpm of HPl flow through DHV-11. Table 2. APS Matchup Times for B-LPI Pump Operation. P 1.0 ANS 1971 Decay Heat 1.2 ANS 1971 Decay Heat Pressure Spray Decay Heat Effective Boron Decay Heat Effective Boron Flow Matchup Time Dilution Time Matchup Time Dilution Time (psia) (gpm) (br) (br) (hr) (hr) 14.7 114.5 19.1 22.5 32.8 39.0 35 102.8 26.3 31.7 45.0 53.6 45 97.0-31.9 38.5 53.9 63.6 60 86.4 46.4 55.8 75.6 88.9 75 75.8 68.9 82.2 107.8 128.6 105 46.3 271.9 378.1 483.6 644.7 = (NOTE: APS initiation must occur three hours prior to the matchup times listed on the above table to allow for the APS flow to fill the pressurizer such that the effectrve times are accurate.) ~ 15

1 Frtmstoma Technologins Inc. 86-1266272-02 Table 3. APS Matchup Times for A-LPI Pump Operation. 1.0 ANS 1971 Decay Heat 1.2 ANS 1971 Decay Heat Pressure Spray Decay Heat. Effective Boron Decay Heat Effective Boron Flow Matchup Time Dilution Time Matchup Time Dilution Time l (psia) (gpm) (hr) (hr) (hr) (hr) 14.7 125.5 14.3 16.4 23.5 27.6 35 114.7 17.9 21.0. 30.7 36.3 45 109.4 20.7 24.4 35.8 42.2 60 100.1 27.9 33.5 47.8 56.4 75 90.7 39.2 46.4 64.7 75.8 105 67.3 93.9 112.8 147.8 181.7 (NOTE: APS initiation must occur three hours prior to the matchup times listed on the above table to allow for the APS flow to fill the pressurizer such that the effective times are accurate.) Table 3.1. APS Matchup Times from A-LPI Pump With DHV-5 Isolated 1.0 ANS 1971 Decay Heat 1.2 ANS 1971 Decay Heat Pressure Spray Decay Heat Effective Boron Decay Heat Effective Boron Flow Matchup Time Dilution Time Matchup Time Dilution Time (psia) (gpm) (hr) (br) (br) (hr) 14.7 135.6 11.44 12.89 18.00 20.69 35 125.8 13.5 15.33 21.94 25.56 45 120.9 15.00 17.11 24.86 29.03 60 112.6 18.44 21.53 31.81 37.22 75 104.2 23.75 28.19 41.25 48.06 l 105 84.3 48.89 58.06 78.89 91.94 (NOTE: APS initiation at pressures below 75 psia must occur two hours prior to the matchup times listed on the above table to aliow for the APS flow to fill the pressurizer such that the effective times are accurate. A time of 2.3 hours is needed at 105 psia.) 16

2 e e 0 l 7 l z z z z 1 2 o o 7 N N 2 T T 6 F F 6 C C 2 o o T T 1 6 p ~ 8 m u 5 6 P V V H H D E D I P F-8 8 7 L 3 V V A H H H D D D e P'( P k h 1 'J t h 2 l t E E F F" m i w 1 1 H H s D D h t I p P a 7 H P u 3 o A T w T o y l a 0 1 r 1 1 F p 1 1 S e V J 3V p xu J H L VH m A D D u R 1 Z 4 S P -V o o T H A 0 i B 1 2 2 t D 1 1 i P-P V-v p H I R H I i D D D m T T u S S D W X W B [ ]9 .Fk B 0 3 4 L m 'J m o 4 V V 5 ro D r 3 I H 3 F F I H V D D V y H I D D D I .c 2 3 n 3 4 4-I V VA N s R I Hk V l B D D i e C R ig 4 o g 1 e lo L X X n e t r o h l c u I 3 4 p e g V V i I I T F D D 3 l l e g mo ta ma rF

20 le e z l 8 z z z 1 2 o o 7 N N 2 T T 6 F F 6 C C o o 2 T T 1 6 p 8 mu 5-P V l iD E IP F-g 8 L 3 y { l B i o D e Pk h 1J J t h 2 I E E t F F i w 1 2 1 1 l I s i V I D D h i iD t I IP P a s Pk I I I a 7J o I P t oT T w l y o ya Y 0 l r 1 F p 1 S 3-V p x Pk yI u 's l m A 1J D q u R I Z 4 S P -V o A 0 1 I B o T l 1 1 2 2 t D 1 1 P v V( P p I i I t I i m i D D D T T u S S D W W B I ]0 7 B 9 + L m ] 3 4 3 m o 4 V V o D r r 3 I I F F l l H V D D I D D I .cn 3 i s R B C R B i R g o 2 ge lo L [ [ n e t r o h l u I 3 4 c p e g V V m i I I T F D D S l I u e B m R o ta ma rF

N 2 o i f 9 d 3 e l e NN N u u E E i (O U U CD t o o l N d H b v-j a u s ^ f O-e n 0-S9 7 T7N

A A

J O Q <t i Ae e B a h 6 Obb .c r,n r, YNO h )(+d 6.E l =)( m 4 c i = 9 3 = 3 mE Q Q = =

0. O 0

O E g-A 4

Y 9 *G

$g Yh O

y

~~~ n. f a x Ae E, O Ga m a S V> b-3 5# N 8 VE W e a b rh 1 mE s n= 5 a e i= -f C X cc = f l. 's d. d. T 3 O O .- = O O W.. ? cH E rl ra r, u = u ? T rl N W O e

s,;

e e n, e 3 w Mb b A m 5 5 0 8 y y l EX EX! M ? E o o B ) a a: .9 O P O A LA LA 4 C y y3 73 r m 5 O O E m h b 5 5 5 o .9 E LL 2 i m E l E u.

N I 9 f 2 o N l N o I N Z Z b U U eh d> E m o a O ? Q. BN P N 72 d ' 4 5 g ^5 w a n D b D = .C Q Q .C ~ v m .t:: 2 N N m + = C 7 C.! .C 3 = =

G

= Q Q d C V 5 E O-g a x 2 C v >7 M 7 u 5 T = C <M Q. Q Q (f) a: D T M F > 5 s t = 5 a m = Q X 2 2% S 3 5 5 5 m kJ Il Tl LA A m e e rm ? T r, e 2 e m 2 3 m ? = = m A M Q Q A d 0) = = O' D Q Q N m w T T C 1 >1 P >v

J L

=A u) M e O Q .O I e C) T .o O P O A LA gj T 5 F, F, O o ? Y a ~ s a e u b U 5 o o e .9 g E u. .9 i m E E u. ]

l f N o o O h b N NN z i N e e u o o N ~o a a f c m Ea a. a z ,,a _0. 5 L g as J = = s e2 4 ^ 5 5 5 e -n >q-n .C g )(E .3 m)( 4 = = s .= a a o O [ O. O LJ. = 3 42 F' ' # i o e h lf ~ o L1. e 1 e S Y T T 2$ C s. u __ / .O r, a To -o M Q) N y 'c' {h i ~ ~ b d_ I d j = a> O Q o J o W z = u r_, E F, ? T u = r3 E J E n 2 u. 9 = = m u Q c a S t l I = 5 O d O n >X >, P ~~ z' e ^ e a s m .e e 1 c) O l 0 ? O lf) J E o a NX ~ ? T a o U y E p = = o Q Q v) G) ll-E E .9m E E u.

2 e 0 2 lz z 2 2 o 7 N 2 T F 6 C 6 o 2 T 1 p 68 m u 5 6 P V V H I IP D E D F L 8 8 7 3 B V V -H I I l l e D D D h t L h J l t 2 E E i w F F 1 1 s ~ l l i i h D D ta I p P P Pk p l l a 1 o w T" o T l y g a 0 F g r l p I y n S 4 V x o u J Pk l i i A 7J D tc R 1 e Z 4 P j V n oT A 0 1 I B I i 1 2 2 D 1 1 1 g P V V-P I I I I e I D D D l I L T T t S S o W W m '0j ( B H B I 3 4 a m o L o 4 V V 5 r r 3 I i 3 F F D l l V D D V H I I D m" l ID c D 2 n 4 3 V 1 I I s F s R B D B R ig C o g L l e J o 6 L [ [ n t e o h l r I 3 4 c p u e V V m T g u I I l l D D S i e F DR mo ta ma rF

2 3 0 2 0 2 8 ~ 1 7 ~ ~ 2 ~ 6 ~ 6 ~ 2 ~ ~ 1 ~ 68 1 .F............+..i.......b,.;* 06 1 de e e w t iv v la i o t t o c c F ............. q..1.... .i..n.. f f Is l f f 5 0 e e 4 1 E E - p V y y a a a H r r D G p p S S f t x x f u u u E o )t A A S r r P 0 h a l........................ z z A 2 t e P P IP 1 i WH I I L y P P B e a L L mc A B A ie TD ............ t .....t 4^ X 0 n1 0 s 1 o7 r u i t 9 o u1 h l iS D e N m nA i o ............q-................,..... ' -. ;l..... 8 0 T r2 o 1 B t ea vt W i t ceM ,.........,.;...........e......,.....'- 0 .;l 6 f f 8 E6 5 S 2 P( A 7 ,.........,. t. ...e ,s 0 4 c n e I r s u e g m i i i a g F o l o ............,;.,.l 0 2 n h c e T e m o 0 t 0 0 0 0 8 6 4 2 a m

g. mC

3me*'D L

a rF

2 0 4 0 2 . O 8 2 1 7 2 6 6 2 1 6 0 3... 4.I, A. l ,.i..j...i,..... d 0 .....I 6 8 1 e e e t 1 v v a t i it lo a t c c s e e I t f f f f 5 W E E V M y y a a H r r D p p 8 6 I,.. .-. t,.. l ..e l-f 0 S S - 4 f 1 x x 5 u u E 2 A A S ( r r P z z A w P P 1, o - - P P I L l I P B F L L 0 p .....,., I,... i I, I t l.. i.. l A B A .....I 2 1 a G O^ t u o )t h a t e 0 iW H,. .....,I. .t I l.. i.. t,..........'r.l 0 s 1 r y u e o a mc h O ie T D e m n i o 1,........... +. I... l.....{..........' .l.'......! 0 T 7 8 i t 9 u1 l i D S N nA o r o a 4.O... l..... j..........* .l.'......! 0 6 B e v it c e f f .c E ,...........-... 5 I l. -.. l ...i...l . l. '...... ! 0 4 n S I s P e A ig o l 8 o 4 e 0 r l..... l. ....l l. 2 n h u 'u ) c y 'u g s, '\\ e i '/ T F e m o t O a 0 0 0 0 0 8 6 4 2 ma r.nL-g aC 23vve6n. ii - rF

Framatomo Technologies Inc. 86-1266272-02

3. Summary of Methods The core boron concentration was calculated as a function of time for the LOCA

transient using a Microsoft EXCEL spreadsheet.

This model contains six control volumes and twelve junctions, it tracks the liquid and boron inventories in the core, lower downcomer, RCS outside of the core and downcomer, CFT, sump, and BWST. From the RCS pressure and temperature time histories providea by a RELAPS RCS thermal-hydraulic model, core boiling and flashing rates, ECCS flows and condensation rates, RCS break flows, building spray flows, core and downcomer esturated liquid mass changes, core solubility limits, steam carryover, and hot leg nozzle gap sizes are calculated. These pressure-or time-dependent parameters determine the flows of liquid, steam, and boron between these six control volumes. The model includes provisions for dump-to-sump flow through the decay heat drop line, nominal hot leg nozzle gap flows with user supplied multipliers, and excess ECCS spillage from the downcomer and core regions to containment. Further, the model_ considers liquid hold-i up volumes in containment, a variable ECCS temperature during sump recirculation, and a boron transport delay between the core and the sump. 3.1 List of Kev Assumotions The following list contains key assumptions used in determining the limits for the core boron concentration (Ref. 9). The first four assumptions apply to calculations used to determine the hot leg nozzle gap size and have no bearing on analyses that do not use or credit hot leg nozzle gap flow.

1. The hot leg nozzle gap is calculated with methods that assume an isothermal temperature in the RV shell.

The calculations are also conservative if the temperature gradient is positive from the inside to the outside (i.e. Inside is colder from steam or liquid cooldown). The calculations are non-conservative if the inside of the shellis hotter. c 25

f Framatomo Technologies Inc. 86-1266272-02

2. There are no plastic deformations of the original measured as-built gap rC sizes that have reduced both gap sizes. Shifting of the RV internals may reduce one gap but the other should open up accordingly.

It is the average gap size that is important for the gap flow calculations.

3. The dead weight of the vessel and water, the hydrostatic pressure acting on the internals, and the pipe loads on the hot leg nozzles have been neglected for these calculations. These contributions are expected to be negligible with some contributions opening the gap and others closing the gap.

4. The RV deflection at the nozzle belt due to pressure and temperature can be approximated by equations valid for a thick-walled cylinder. There are four cold leg nozzles, two hot leg nozzles, and two CFT nozzles attached to the shell in this region. The reinforced nozzle forgings add stiffness to this region, such that the thermal expansion can be represented as a thick-walled cylinder without any openings or attachments.

5. The boron concentrations in the, core, upper plenum, core baffle, and outlet annulus regions are uniform. The vesselinternal circulation due to the core boiling keeps these regions well-mixed and uniform in temperature.

6. The boron solubility in water is representative or conservative for use in l

determining the solubility limit when the sump pH control additives are l injected back into the core during the sump recirculation phase. l

7. The sump pH additives that are concentrated in the core will not result in any other compounds that could precipitate and block core flow or totally l

obstruct the gap flow.

8. The LPI flow must be throttled to an actual flow of 1600 gpm or less for the APS effectiveness calculations summarized in this document that consider only one LPI pump available. If both LPI pumps are available, the B-LPI train is used for ECCS injection, and the A-LPI train is used to provide APS flow and 600 gpm of HPI flow only (i.e. no LPI).

9. The DHV-42 or DHV-43 valve open areas are based on a nominal stroke time of 6.0 seconds. The sump screen analyses were performed with a stoke time of 6.5 seconds (A,,n = 2.56 in'). The minimum stroke of 5.5 2

seconds (A,,n = 0.0864 in ) provides adequate flow for boron dilution. 26

l Framatoma Technologics Inc. 86-1266272-02 h 3.2 Summarv ofinouts The inputs used in the analyses are summarized on Table 4. 3.3 Additional Considerations NRC reviews and discussions with FPC have led to the inclusion of certain specific considerations beyond the basic inputs in the boron dilution analyses. This section presents a summary of these concerns and the approach taken in the analyses to address them. 3.3.1 ECCS Temoerature Durina Sumo Recirculation The original boron dilution analyses (Refs. 7 & 8) used a constant ECCS inlet temperature of 140 F during sump recirculation. An analysis performed by FPC suggested that the ECCS temperature on sump recirculation could be closer to 180 F (Ref.13). The increased temperature results in additional boiling to remove the decay heat and delays the time at which a given flow rate (such as with APS) will match core decay heat. FTl reviewed several long-term containment analyses and observed that the sump liquid temperature reached a maximum at the time that the ECCS flow had matched the decay heat bolloff rate and the excess had refilled the vessel to the elevation of the break. Subsequently, the excess ECCS flow would spill out of the break and begin the slow but steady cooldown of the sump liquid temperature. Several LBLOCA and SBLOCA containment analyses were performed to define a bounding time-dependent sump liquid temperature that could be used to determine the ECCS inlet temperature (Ref.14). FPC performed a variety of decay heat cooler analyses with different sump inlet temperatures to define a time-dependent ECCS temperature curve for use in 27

Framatomo Technologies Inc. 86-1266272-02 boron precipitation analyses (Ref.15). As a result, the following equation (Ref. 9) was used to determine the ECCS liquid temperature with time for the boron dilution analyses. l Teccs = max (140,{0.55

min [250,(493*t#28)] + 47.5})

As this equation suggests, early in the event (t < 11.3 hours), the ECCS temperature is 185 F. As the transient progresses, however, the ECCS temperature decreases until it l reaches 140 F (t > 46.6 hours). l l l 3.3.2 Core Mixina Volume A large LOCA depressurizes the RCS to the containment pressure within an hour or j two. At low RCS pressures and high core decay heat contributions, the combination of [] the high boiling rates and large specific volume ratios leads to significant voiding in the core mixing region. As a result, the core liquid mixing volume is minimized (790.5 ft'). With time, the core decay heat declines and the mixture level swell decreases and allows the core liquid mixing volume to increase to approximately 1200 ft'. This l transition evolves gradually after the core refills until a relatively constant liquid volume 2 of 1200 ft is reached. FTl has reviewed RELAPS/ MOD 2 analyses to determine the core mixing volume evolution with pressure and time after trip. The results are included in Reference 5 and shown in Figure 9 for 1.2 ANS 1971 decay heat and in Figure 10 for 1.0 ANS 1971 decay heat. Previous calculations performed in Reference 7 with 1.2 times ANS 1971 decay heat identified that the solubility limit could be reached within 5 to 6 hours when a mixing volume of 790.5 ft' is used. At the time the solubility limit is reached, the core liquid volume is actually larger. Using the larger core mixing volume delays the time that the solubility limit is reached, which leads to a larger mixing volume, etc. This 28

( l Framatomo Technologiras Inc. 86-1266272-02 iteration process can be used to determine the appropriate core mixing volume for use in the solubility calculations. 3.3.3 Uniformity of Sumo Boron Concentration The NRC has asked whether operator actions based on sump boron concentration measurements may be performed at an inappropriate time, because the reactor building (RB) boron concentration might be non-uniform. Specifically, the major i concerns relate to (1) sump transport delay times and (2) the possibility that liquid and boron mass could be retained in isolated regions in the reactor building. These issues are discussed separately in the following paragraphs. During sump recirculation, the excess ECCS injected into the RCS condenses steam, mixes with the downcomer liquid, spills out of the break, and flows back to the RB sump. The spilled flow has a certain boron concentration that can be used to indicate core boron concentration. With time, the core boron concentration can continue to 1 grow until an active dilution method is established. The core concentration increase causes the spilled liquid to have a continuously declining boron concentration trend. This decreasing trend will establish a non-uniform gradient in the RB liquid as it travels l back to the sump. The spilled liquid should have a lower concentration than the RB mixed-mean value. The mixed-mean value would also be less than the concentration that is being recirculated though the ECCS or building spray pumps. Inclusion of this gradient in the core boron calculation method results in faster increases in core concentration following a LOCA. l The method used by FTl for including this contribution is to adjust the ECCS inlet i concentration to that of the mixed-mean sump boron concentration at the post-LOCA time minus the time it takes for one complete sump exchange at the given ECCS and g) building spray flow rates. m 29 l

Framatomo Technologias Inc. 86-12662~72-02 !O l BCeces (@ t) = BCna (@ t - At.uy .ng.) t where: BCeces is the boron concentration of the ECCS at the time post-LOCA, BCns is the boron concentration of the RB, t is the time post-LOCA, and { i At.uy,n.ng,is the sump exchange time interval. This is a relatively simple yet effective method of inc!uding the non-uniform RB ) concentration gradient. j The consideration of liquid and boron hold-up in isolated regions of the RB is important in determining operator actions based,on the indicated sump boron concentration, if l dilute liquid is held up in the RB, the sump boron concentration measurement will indicate a boron concentration that is higher than the RB mixed-mean value. A higher l ~ sump boron concentration indication implies a lower core boron concentration, which i may result in a delayed initiation of an active dilution method when it was truly needed. I Conversely, lower sump concentration will imply a higher core concentrction, which will lead to earlier initiation of an active dilution method. Early initiation of an active. method is acceptable, so long as it does not compromise the ability to provide continuous long-term ECCS flow for core cooling. i The maximum RB liquid holdup volume was calculated to be 12300 ft* (Ref. 6). The possibility of dilute liquid hold up has been considered in the development of the sump l delta curves. Borated liquid hold up has been conservatively neglected, because it removes boron from the analysis that could otherwise find its way into the core. i 30

r l Framatoma TcChnologi S InC. 86-1266272-02 Q Table 4. Key input Parameters for the Boron Precipitation Analyses. Parameter Value Source RCS Power Level 2568 MWt RCS Power Uncertainty 1.02 NRC requirement. Decay Heat 1.2 ANS 71 for compliance cases. NRC requirement. 1.0 ANS 71 for EOP guidance cases Reasonable bound. Actinide Decay Heat B&W Heavy isotopes Reasonable bound. RCS Initial Temperature 579i2 F RCS Boron Concentration 5 2400 ppm BWST Boron Concentration 5 3000 ppm CFT Boron Concentration 5 4000 ppm See Note 1. RCS Liquid Volume 11500 ft3 CFT Inventory 1070 ft / CFT BWST Inventory 5 350000 gal RB Spray Flow (1 pump) 1500 to 1600 gpm from BWST 1200 gpm during sump recirculation (Recirc) BWST Temperature 5120 F i ECCS Temperature during Sump Variable 185 - 140 F See Note 2. Recirculation LPI Flow CR-3 typical, flows 1rqm BWST (See Table 5) g y 2000-2400 gpm dunng recirc HPI Flow CR-3 typical flows (See Table 6) A-LPI APS Flow 2 Table 7 Flows Ref. 2. B-LPI APS Flow 1 Table 7 Flows Ref. 2. A+B LPI APS Flow 2 Table 7 Flows Ref.18. l Sump Boron Conc. Gradient in 2 hr gradient for 1.2 ANS 1971 cases Ref. 9. the Concentration Calculations 3.5 hr gradient for 1.0 ANS 1971 cases Maximum Sump Holdup Volume 5 12300 ft Ref. 6. 2 Sump Delta Temperature 5 +9 F Ref. 3. Uncertainty Core Saturation Temperature +9 / -19.3 Ref. 3. Uncertainty (Tm-T, ,) Sump Delta Boron Concentration 0.8 hour Ref.12. Measurement Delay Time See Note 3. 1 Sump Difference Safety 25% applied to limiting sump difference with NRC requirement. 2 Margin 12300 ft holdup volume with the j boronometer concentration indicated time i delays that will be calculated by FTl l Ave As-Built Hot Leg Nozzle Gap 0.092 in Ref. 7. l Hot Leg injection Flow 500 gpm HLI Ref.11. 1 HPl pump (up to 600 gpm) g 1000 gpm LPI to one CFT Nozzle 'af SBLOCA Core Mixing Volume 1200 ft2 Ref. 9. l l l 31 t l

I Framatomo TcChnologies InC. 86-1266272-02 1 1 Parameter Value Source Downcomer Mixing Volume 1285 ft' Ref. 7. Core Mixing Volume Figure 9 & Figure 10 Ref. 8. DHV-42 or DHV-43 Max Valve 2.56 in: Ref. 4. Open Area to protect sump screen l DHV-42 or DVH43 Min Valve 0.0864 in2 Ref.17. Open Area to protect sump screen DHDL Pipe Temperatures at 306 F Hot Leg and vertical fall Ref.16. Initiation of dilution flow 270 F from vertical to containment wall 212 F in Aux Building Minimum Sump Level 98 to 102 ft Ref. 4. I l Notes: l (1) The total mass of boron available in the system is the important parameter..The initial distribution of the boron may be different than the values used depending upon other plant requirements (i.e. Tech Spec limits, NPSH concems, etc.). Provided that the total boron mass remains similt.r to the values used here, the results will not change substantially. (2) The ECCS inlet temperature curve during the sump recirculation phase has been characterized as a function of time (Ref. 9) by i Teces = max (140,{0.55

min [250$3*t428)] + 47.5})

The CR-3 ECCS inlet temperature should be less than or equal to the value computed by this equation. (3) The delay time is determined by the boronometer flow split and the sump boron lag time for each of the three boronometer intet locations. Engineering judgement and characteristic 3-D mixing analyses performed by FTl were used in Reference 12 to determine an appropriate sump concentration to boronometer concentration measurement lag time. A bounding time of 0.8 hours was used. l 32

Framatomo Technologics Inc. 86-1266272-02 O Table 5. LPI Flow Rates with Suction from the BWST. RCS Pressure LPI Flow (psia) (gpm) 175 0 100 ~2200 50 ~2880 L_ 14.7 ~3060 l These flows rates are representative of those used for core boron precipitation analyses. Variations in these flow rates will not invalidate the boron concentration calculations performed for CR-3, but it could have a small effect on the range of break sizes for which boron concentration j management may be required. l l Table 6. Approximate CR-3 CLPD HPl Flows to the Core. l@ 3 V-RCS Pressure . HPl Flow (psia) (gpm) 1815 ~260 l 1215 ~320 l 615 ~350 14.7 ~350 l l l These HPi flows rates are representative of the flow that reaches the vessel in the core boron precipitation analyses. Variations in these flow rates will not invalidate the boron concentration calculations performed for CR-3, but they can have a slight effect on the break size of interest. t I i 33 l

Framatomo TcChnologi::s Inc. 86-1266272-02 .O Table 7. CR-3 Auxiliary Pressurizer Spray Flow Rates. 4 RCS CR-3 APS Flow CR-3 APS Flow CR-3 APS Flow P From the From the with DHV-5 Closed B - LPI Train A - LPI Train A-LPI Train (psia) (gpm)(Note 1) (gpm)(Note 1) (gpm)(Note 2) 14.7 114.5 125.5 135.6 35 102.8 114.7 128.3 45 97 109.4 120.9 l 60 86.4 100.05 112.6 1 75 75.8 90.7 104.2 105 46.3 67.3 84.3 (1) The APS spray flow rates were supplied by CR-3 Calculation M97-0097 Rev.1 (Ref. 2) for a throttled LPI flow of 1600 gpm. The CR-3 APS flow must be greater than or equal to i these values to support the operator action times in the boron precipitation analyses. (2) The APS spray flow rates were supplied by CR-3 Calculation CSM98-0003 Rev. 0 (Ref. l l

18) for both LPl pumps available. The CR-3 APS flow must be greater than or equal to these values to support the operator action times in the boron precipitation analyses.

O I I e 34

Framatomo TcChnologies inC. 86-1266272-02 O Figure 9. Core Mixing Volume Versus Time at 2568 MWt and 1.2 ANS 1971. l 1500 RCS Pressure 1400

l-----------.'-----------l-----------

++, n C, 1300 4---------- '---- -----'----------- I + >80 psia e i + + + X E 1200

A+. -------K-A 70-80 psia

+ 'A o o 1100

u--

--l----------. m 60-70 psia I l X 50-60 psia en 1000 .5

u---------

l x 40 50 psia - - - - A- - - - - ; - - - g - e- - - - +, 900 e 30-40 psia E + 800

j---------;-----------;-----------

+ <30 psia 700 - LOCA 100 1000 10000 100000 1000000 Time,Is O Figure 10. Core Mixing Volume Versus Time at 2568 MWt and 1.0 ANS 1971. 1400 RCS Pressure 1 e i 1300 ',X n l l + >B0 psia C 1200 ........._l.-..._A..' A 70-80 psia v E l u g u 60-70 psia .m.- 1100 IL o X 50-60 psia A e e o e i > 1000 ' ---------?g---------'----------. x 40-50 psia c E ,[ l e 30-40 psia i

g 900

-A---

,---,-----,-j----------';-----------

+ <30 psia ,g er l SBLOCA t 800 r----- i i i - - - LBLOCA i i i 700 100 1000 10000 100000 1000000 l Time, s 4 ,f' 1 35

l Framatomo Technologias Inc. 86-1266272-02 .h

4. Compliance With 10 CFR 50.46 Requirements Compliance with Criterion 5 of 10 CFR 50.46 was demonstrated for the CR-3 plant by '

calculations that show an effective active boron dilution method can be initiated befo the core can reach the solubility limit. These calculations have been performed using Appendix K decay heat rates (1.2 ANS 1971 DH standard) to define the minimum time for operator actions to initiate an active dilution method (Ref. 9). The core boron concentrations can be maintained below the solubility limit by using two separate methods at CR-3, namely flow via DL RB-Sump and APS. Compliance is demonstrated by showing that at least one of the active dilution methods can be established prior to the time that the core reaches the solubility limit without crediting hot leg nozzle gap or RVW entrainment or liquid overflow. (It should be noted that credit is only taken for RVW liquid overflow for smaller RCS break sizes that can be refilled.) In the event that a single failure renders the active methods inoperable, calculations performed in References 7 and 8 have shown that the hot leg nozzle gaps are an effective backup dilution mechanism that prevents the core from reaching the solubility limit until an active method can be established. The time that it takes for the boron concentration to reach the solubility limit is governed by the core concentration increase and the RCS pressure or temperature. The core concentration increases because of the core boiloff, which is governed by the integrated core decay heat rate. The core concentration is relatively independent of break size or RCS cooldown rate other than the effect of the core mixing volume and RCS temperature, which dictate the boron solubility limit. The time-dependent core i mixing volume was used in simulations of the spectrum oflimiting CLPD LOCAs (from a i full double-ended guillotine LBLOCA to 0.05 ft SBLOCA) to define the limiting core 2 boron concentration versus time (Ref. 9). An iterative approach was used to converge on the mixing volume that coincided with the time that the core boron concentration reached the solubility limit. Iterations were performed with RCS saturation pressures I 36

I Framatome Technologies Inc. 86-1266272-02 [ from 14.7 to 40 psia to define the minimum time to reach the solubility limit during the time-dependent portion of core mixing volume curve. Figure 11 and Table 8 present i the converged results of these analyses as well as the minimum solubility times at higher pressures where the mixing volume is at 1200 ft. Figure 11 also shows the RCS pressures at which the DL RB-sump method is available and the APS matchup times (not including the pressurizer fill time) for A-or B-LPl train operation. Based on this figure, boron dilution can be initiated via the DL RB-sump method if the RCS { pressure drops to an indicated value of 54 psia (error corrected 47 psia) prior to the l l APS matchup time. If the A-LPI pump is operating, the matchup time at 54 psia is as j l early as 44 hours, while it is 67 hours if the B-LPI pump is operating. (Note: The A-LPI APS can provide adequate core boron dilution at any time after 36 hours. Further, if both trains of LPI are available and the A-LPI pump is used to provide only HPI and APS flow (DHV-5 isolated), APS can provide adequate core boron dilution any time after approximately 24 hours.) l The compliance calculations show that APS or DL RB-sump flow can be initiated to I control the core boron concentration at or before the time that the core could reach the solubility limit. Once activated under conditions at which the methods can be used, they are effective in preventing the core from reaching the solubility limit. This combination of methods is not single failure proof. That is, one failure could take out one (with a valve, valve motor, or power source failure) or both active dilution methods (MCC-3AB failure). With a failure of this type, calculations have shown that the hot leg l nozzle gap flows are an adequate backup to provide effective core boron dilution until l the active method can be established (Ref. 7 & 8). l 37 i l

f Framatoma Technologies Inc. 86-1266272-02 I l i Table 8. Minimum Solubility Time vs RCS Saturation Temperature and Pressure ) l with 1.2 ANS 1971 Decay Heat. RCS Saturation Pressure RCS Saturation Time to Reach the (psia) Temperature (F) Solubility Limit (hr) l l 14.7 212 7.6 20 228 10.4 25 240 14.1 30 250 26.9 40 267 47.2 47 277 67.2 50 281 79.4 60 293 148. 67 300 345. 73 306 Never 4 38

20 9 3 2 u 0 8 7 1 2 6 6 2 1 6 8 I- 'r.' p p ........ ' 6 0 m m 1 t u u a S S t e e oi r ot me H ee ut i vv sp pLiv i 4...t... M 4..' EEnr ol y ........' 0 iis m myc t y t tcc e ui e t ya r u l f eePD Dif f f b E t c f f r u e 4 ofof o 1 l ibD a yyi aa aP PS t rp r r pptujdjmS u1 d SS c xxA A Au l o7 x ymu 9 uuptyt S inA ni 1 AAmiaMr ni oS r r uat z eP zzS t r t r 0 eN PP e et - ..... 1.. ' 2 ...l. oc ci sI 1 t n oP mA n pU UpL I I PP m xmB i2 LL n T uiao& 1 ABDMMCA d nh t 0 X 0 + . 0 ai 'I_ ... l.. ' _ w 0 .... t. b e ' 0 s s 1 mo' e n ru o i i h t Tu e l pi m uD i h l....... 'l l-l 0 T n l-l l I 8 c t o ar Mo B t Wve Mi l-l l ... t. e 6 t 0 c 8 A" 6 5 r 2 o .w 1 o 1 l l .';;' j' e e 1 e 0 F .c e 4 n r p u I a g s iG e F i t g u I o o ...l ..l .'. ; ;l l t lo h ...g.......'! 0 n t 2 i h W c e T e m o .O t 0 0 0 0 0 a 8 6 4 2 ma sg..2a,,gwO rF

1 Framatomo Technologias Inc. 86-1266272-02

5. EOP Guidance for Post-LOCA Boron Dilution Compliance with 10 CFR 50.46 requirements was demonstrated by calculations that established initiation times for active boron dilution methods with a decay heat of 1.2 times the ANS 1971 standard. Due to the additional decay heat contribution, these times are very conservative and could prompt. premature realignments of the ECCS system to manage core boron concentrations in the unlikely event that a CLPD LOCA of the critical size occurred at CR-3. In order to preclude premature realignment, a

- more realistic, yet still conservative, decay heat (1.0 times the ANS 1971 standard) was used to develop minimum times for activation of boron dilution methods. In addition, a method was developed to calculate the limiting core boron concentration based on the measured sump boron concentration. The minimum times to reach the solubility limit and the sump sampling methods can be integrated into the CR-3 TSC guidance for post-LOCA boron concentration control. 5.1 Minimum Times for Active Boron Dilution without Sumo Boron Samolina The TSC guidance calculations were performed with the realistic decay heat levels (1.0 time's ANS 1971) to determine the rate at which the core boron concentration would increase and to define active boron dilution initiation times for cases when the sump i sampling method is not available. These analyses were similar to the compliance calculations in that conservative boundary conditions were used that maximized the core boron concentration based on the most restrictive combinations of break size and break location. Like the compliance calculations, no credit was taken for passive boron dilution mechanisms such as RVW liquid entrainment or hot leg noz& gap flow, because both mechanisms are transient-specific and time-dependent for which the magnitude or effectiveness of the flows cannot be directly measured or validated without sump boron sampling. These calculations determined the minimum times for operator actions to reconfigure ECCS flow paths, to shut down an operating LPI pump, 40

i Framatome Technologi@s Inc. 86-1266272-02 or to throttle ECCS flow rates in the event that the core concentration could not be determined. Figure 12 and Table 9 show the minimum time to reach the solubility limit versus the uncertainty-adjusted saturation temperature. That figure shows the APS l effective times versus the uncertainty-adjusted saturation temperature. The actual 4 saturation temperature is increased by the maximum uncertainty of +9 F for all of the curves l 5.2 Sumo Boron Concentration Method The post-LOCA management of core boron concentration has typically been demonstrated with time-based initiation of active boron dilution methods. While this i i method is effective, it does not take into consideration the effectiveness of the hot leg nozzle gap flows or the RWV liquid overflow. A method has been developed to identify appropriate times to initiate an active boron dilution method in the event that the passive mechanisms are not effective (Ref. 6). This method allows the TSC and the operators to infer the core boron concentration using measurements of the sump boron concentration during the sump recirculation phase. The underlying premise is that if boron is depleting in the sump, it must be concentrating in the RCS or core. The break location that could result in significant core boron concentration build up must be located in the cold leg pump discharge region and must be of sufficient size that the RCS loop piping cannot refill. Under these conditions, liquid could be retained in the reactor vessel or cold leg pump suction (CLPS) regions. The liquid that is trapped in the CLPS regions will be isolated from the reactor vessel and its boron mass content will not change significantly during the transient. Therefore, the only regions that wiil have variable boron concentrations are the reactor vessel or reactor building regions. If the sump concentration can be measured, then the core boron concentration can be determined from bounding calculations that take into consideration limiting boron concentrations and measurement uncertainties. 41

Framatomo Technologi::s Inc. 86-1266272-02 CR-3 has the capability to samp!e the boron concentration of the 'ecirculating sump r liquid using a boronometer and a sample line that is located in the sump. Once the sump concentration is known, calculations can be performed to determine if the core is approaching the solubility limit. These calculations require that the entire liquid and baron mass contained in the RCS, CFT, and BWST are known, such that a system mixed-mean average initial boron concentration can be calculated. The difference between the initial mixed-mean average value and post-LOCA sump concentration will be used to evaluate the margin between the solubility limit and the core boron concentration. This margin can 'then be used with the RCS saturation temperature to determine if boron dilution methods are needed and which methods can be used. The sump difference method calculates an RB mixed-mean boron concentration (ppm liquid), BC,nu o.,n,,n, by taking the ratio of the total boron mass (Ibm B), Bw, to the total liquid mass (10'lbm), M., BC .,n.n = B / M.. The totalliquid mass is calculated by the sum of the RCS, CFT, and BWST liquid mass injected M. = Macs + Men + Maws 7in;, The total boron mass is determined by the sum of the products of the liquid mass and the boron concentration B = Macs

BCacs + Men
BCen + Maws 7 n'BCswsr.

The boron and liquid mass during the sump recirculation phase of a LOCA will be distributed in the core, downcomer, and reactor building. 42

Framntome Technologics Inc. 86-1266272-02 B., = B., + Boe + Bas The boron and liquid mass retained in the core at the boron solubility limit can be calculated as a function of RCS temperature. Using these core masses, the total boron and liquid mass in the downcomer and sump can also be determined as a function of RCS temperature. The core boron mass at the solubility limit is calculated as the product of the boron concentration at the solubility limit (ppm), saturated liquid density (Ibm /ft'), and core mixing volume (ft'). Bas a oc = B - B., = B w - (BC,,,,/ V ,n,,,ng y,

p, oj.

o Mas a oc = M,w - M., = M,w - (V.,5,,n,,,

p, oj.

The appropriate core liquid volume for the boron concentration calculations with realistic decay heat remains approximately constant at 1200 ft' over the post-LOCA time period of interest. The boron concentration in the downcomer and sump will be similar because of the high ECCS recirculation rates that keep the downcomer and sump relatively well mixed. With this consideration, the RB and downcomer boron concentration when the core is l at the solubility limit is then calculated by BCao a oc = Bas s oe / Mas a oc This calculation can be repeated at a variety of temperatures to define a sump concentration at which the core would be at the solubility limit. This curve could then be developed for a specific combination of BWST volumes and RCS initial concentrations at the time of the LOCA. However, a single curve can be devised to cover all combinations of mixed-mean liquid and boron masses by changing the basis of the limit to a difference curve. A variety of cases were evaluated with different RCS, CFT, and 43

Framatomo Technologies Inc. 86-1266272-02 BWST liquid masses and boron concentrations to define a b~ unding sump boron o difference curve that can be used to establish operator action times considering instrument uncertainties and reactor building holdup volumes (Ref. 6). Figure 13 demonstrates these results. Concentration differences below and to the right of this curve identify acceptable operation. Concentration differences above and' to the left of this curve indicate that core boron precipitation could result if an active dilution mechanism is not established. A calculation was also performed'to define conditions under which hot leg injection via reverse flow through the DHDL could be initiated (Ref.11). This limit, also shown in Figure 13 and Table 9, ensures that HL1 will not induce boron precipitate due to the mixing of hot borated liquid with cold deborated liquid. If HLI is not established prior to reaching this limit, one of the other forms of concentration control should be used (APS or DL RB-sump). Concentration differences below and to the right of this curve identify acceptable times for initiation of the HLI method. Concentration differences above and to the left of this curve indicate sump concentrations that could cause boron prec,ipitation in the hot leg piping. Figure 13 provides TSC guidance for MLl based on sump concentration. If the sump concentration is unavailable, the TSC needs guidance for establishing this method based on time. Reference 9 gives the time versus uncertainty-adjusted saturation temperature shown in Figure 14. This additional TSC guidance, when combined with Figure 12 and Figure 13, provides a composite set of instructions that can be used with or without sump boron concentrations to manage the core boron concentration post-LOCA. 44 i

Framatomo Technologi::s Inc. 86-1266272-02 5.3 TSC Guidance l l All of the methods for monitoring and managing the core boron concentration post- \\ l LOCA have been presented in the previous sections. This section integrates them into l a set of instructions for EOP or TSC guidance during the long-term cooling phase of a t LOCA. These instructions should be followed whenever inadequate subcooling exists, or has existed for greater than five hours, and the core exit temperature is less than 305 F (314 F error corrected). Calculations have shown that even if all the boron in the RCS, BWST, and core flood tanks were concentrated in the core region, the boron would remain soluble at temperatures above 305 F (saturation at 72 psia). Core boiling is the concentrating mechanism that will continue until core exit subcooling is restored. The restoration of core exit subcooling is assured by establishing.a liquid flow through the core that not only suppresses core boiling, but also effectively dilutes the core boron accumulated during the period of inadequate subcooling. At lower temperatures, the boron concentrations could result in precipitation and possible blockage of core cooling channels. Therefore, if core exit subcooling margin is lost for an extended time period j (greater than 5 hours), then this guidance must be followed to prevent boron precipitation. The post-accident core boron concentration monitoring and management strategies are based on Figures 12 through 14. These strategies use core exit temperatures, time, i and sump boron concentration to track the transient evolution and determine when an active dilution method is required and which of the three active methods (APS, dump to sump, or HLI) are appropriate for use. The preferred active dilution method is APS, because it does not require significant realignment of the ECCS flow paths (needed for HLI use) or tight control of DHDL valve positions to protect the sump screens (needed for dump to sump use). Once in this procedure, the sump mixed-mean concentration must be calculated, the boronometer measurements must be taken, and the transient temperature-time histories must be recorded for use in this guidance as outlined. 45

~ Framatoms Technologics Inc. 86-1266272-02 ~ Figure 14 presents the minimum time post-trip that the core could reach the solubility limit (or mixing limit for HLI) as a function of saturation temperature. This curve is used exclusively if symp boron sampling is not available. It is used to determine the time for initiation of an active method or to.make a decision on the use of hot leg injection. An active method should be initiated before crossing the lines identified in Figure 14. If sump boron sampling is available, the sump delta concentration should be plotted against the core exit temperature on Figure 13 with time noted.at each data point. If the curve stays flat (i.e. near zero delta concentration), some passive dilution mechanism is working (RCS refill, RVW liquid overflow, or hot leg nozzle gaps) and an active dilution method is not needed at this time. If the, curve begins to approach the solubility or mixing limits, an active boron dilution method may be needed. The methods that are effective for bo'ron dilution can be derived from Figure 12. Figure 14 can be used along with Figure 13 to delay the initiation of an a'ctive method based on the sump-delta limit. The sump-delta method provides a very conservative limit that prevents the core from reaching the solubility limit. These conservatisms may prematurely indicate that active boron dilution is needed. That is, if the sump-delta method indicates that an active method is needed by 10 hours, but the minimum time to solubility at a given temperature is 20 hours, then active dilution may be delayed until just before the later of the two, or 20 hours. By the same token, the time-based actions do not have to be used if the sump delta concentration indicates passive dilution is occurring. In other words, initiation of active boron dilution is acceptable and adequate l at the latest activation time derived from the combination of sump-delta and time-based limits at the given core exit temperature. 46

Frcmatomo Technologies Inc. 86-1266272-02 5.4 Demonstration of Boron Dilution Methods Three cases are provided as examples of each of the three CR-3 active dilution methods to assist in the understanding of how the three sets of EOP guidance curves can be used together to determine when boron dilution is needed and which methods can be used. The examples further demonstrate the significant conservatism included in the sump-delta curves. It is clear that the margin between the indicated and real solubility limit is significant and adequate,to ensure initiation of active dilution methods before the core reaches the solubility limit. (NOTE: The A+B LPI APS effectiveness curve is not included in Figures 15 through 17. If both LPI pumps are available and the A-LPI pump is used only for HPl and APS flow, the core boron concentration will follow the same trends as demonstrated, however this method will be effective sooner in the transient.) 5.4.1 Case 1. Boron Dilution via Dumo to Sumo Case.1 is a beginning-of-life (BOL) CLPD LOCA with a break size of 0.12 ft. It 2 simulates a single failure of the A-emergency diesel generator (EDG). The progression is shown in Figure 15. The long-term core exit temperature drops below 280 F within 5 hours post-LOCA. At this time, the operators enter the post-accident EOP guidance criteria, because inadequate subcooling has persisted for at least five hours and the core exit temperature is less than 314 F. They calculate the system mixed-mean boron concentration, begin to measure the sump boron concentration with the boronometer, and plot transient progress on' Figures 12 through 14. The first several boronometer measurements indicate that the sump delta concentration difference is increasing. At approximately 9 hours, the sump delta reaches the HLI mixing limit. A cross reference with the time-based HLI mixing limit on Figure 14, reveals that the real decision to initiate HLI does not have to be made until 47

Framatoma Technologias Inc. 86-1266272-02 approximately 30 hours post LOCA. Therefore no active dilution is initiated at this time. They continue to measure the sump concentration and plot 'the course on each figure. At 15 hours, the sump delta concentration has approached the sump-delta solubility limit, but the time-based limit is still 15 hours away at the current RCS temperature trajectory. At the end of the first. day, the TSC staff concludes that active dilution is needed and the preferred option of APS with the B-train is not effective at this time. However, the temperature is in the acceptable range for dump to sump, plus HLI is still a viable option because the time-based mixing limit has not been reached. The dump-to-sump method is selected and 'the operators are instructed to initiate it by 25 hours. Once this method is initiated, the core concentration tums over ' uickly as confirmed by q the sump concentration increase. The minimum solubility margin was in excess of 27000 ppm at 25 hours. 5.4.2 Case 2. Boron Dilution via Auxiliary Pressurizer Sorav The second example is a slightly smaller CLPD break, 0.08 fta, at BOL with a single failure that prevented use of the A-LPI pump. The progression is shown in Figtce 16. This break plateaus at a higher pressure and temperature than the previous case. At five' hours the operators begin to measure the sump boron concentration and monitor the transient progress on the time-temperature curves. By 15 hours, the HLl mixing limit is approached on the sump delta curve. By cross-reference to the time-based limit, the TSC' concludes that the time-based mixing limit is still 30 hours away, so no action is required at this time. The sump-delta difference continues to increase toward the solubility limit. At approximately 40 hours, the TSC determines that the B-train APS method would be effective by 45 hours. Since APS is the preferred dilution method, the' TSC instructs the operators to initiate APS at.42 hours, allowing three hours for the pressurizer to fill. Once the pressurizer is full, the APS flows into the hot leg and begins a net reverse liquid flow through the core. The liquid flow slowly but steadily reduces 48

Framatome Technologies Inc. 86-1266272-02 the core concentration. The minimum core solubility margin calculated for this case was greater than 37000 ppm at 45 hours. 5.4.3 Case 3. Boron Dilution via Hot Lea injection The final case also simulates an 0.08-ft case but with end-of-life (EOL) RCS bor 2 concentrations. The progression is shown in Figure 17. This case uses a dilute liquid holdup volume in excess of 9900 ft*, with a single failure of a valve in the APS piping that is not discovered until the preferred APS method is attempted at 30 hours. With the failure of APS, the TSC instructs the operators to use HLI. Use of this method is not restricted because the time-based mixing limit has not been exceeded. At 40 hours, the operators initiate HLI to manage the core boron concentration. The minimum core solubility margin for this case was 56662 ppm at the time of the HLI initiation. (NOTE: The application of HLI at CR-3 is currently under review by the NRC under a separate submittal. This demonstration is presented only for completeness and to demonstrate the mechanics and principles behind the method.) 49

Framatoms Technologies Inc. 86-1266272-02 Table 9. Minimum Solubility Time vs RCS Saturation Temperture and Pressu're ^ with 1.0 ANS 1971 Decay Heat. l 1 i RCS Saturation Actual Indicated Time to Reach Pressure RCS Saturation RCS Saturation the, Solubility Time to Reach i (psia) Temperature Temperature Limit HLI Mixing Limit l (F) (F) (hrs) (hrs) 14.7 212 221 13.06 13 ) l 20 228 237 17.00 17 i 25 240 249 23.69 23 30 250 259 32.22 28 40 267 276 56.94 40 47 277 286 81.67 48 49.1 280 289 93.06 51 50 281 290 98.61 52 60 293 302 193.61 64 63.1 296 305 348.89 68 l 65.4 299 308 >350 72 73 306 315 Never 83 i l ~ l 50

2 0 1 5 -2 7 0 6 2 3 6 6 2 1 6 n. 8 n d o e o i tud i ,] ,t l l l l _.... l De .. j. 1.... l l l . - 0 t i e l 4 a 3 n r t nt n oo r n e o c B is n o C ,,l D l l l l ..l .. *. l..... l l l 2 e 0 r n iz 3 o u r s s o ,s/ j ~ e B ). h ~ r p 1 t e7 o. e v9 iM e h s n v l t S C isit i l i t 1 c f c P e A S .-l l l l A S e 0 o ,....l l . Pf 3 F f 0) t N A E S ( r e P oA r A u f t e 0 a h s ~ r t ~ e r e1 ~ p o r f h 0 m ~ ut e ~ e t i ',l .[.

'l l

l l h..' l t ..l ....,. '., l 0T im aw 8 t 2 n r w et o ~ i lo pW t ~ ) a la mM 1 ru o 7 e t t S a s T8 N S e 6 A S m d5 C it 0 n2 - d d 1. l l ...,l j.. l l 60 R pu a( e e 2 ) h t t it l a a d tc so c i t m e nd a er ic i L lo t e d d a o m mt . n I t id I n y e n u e i 1 1 i s l e h To _. 7 7 it il i DN imb 5 i t C S S L lo u c V ne p i N N p S H oB t u A A ic D. l l oy l. i..... ,l 0 ir r c h _.. 0 0 e m 4 r u I B a 2 p c p B e M s 1 1 P mP c t r n a I P a i B ) ) u L P I x in o M I h L L M M S e e _ B A d d A j j ( ( ( r A A 2 i f f h f g f f f E t t t 1 E E r r o r e e ._ S S c c S l l ,...,l ..l . ;.....-~ U 0 u lo e _ P P n n P 2 c .l 2 c r A A U U A o n u h t g s I. M c u i e F m T n o e it a m i it o 0 in 0 2 t 0 0 o 0 0 0 0 0 S a 4 2 o 8 6 4 2 P 1 1 3 m A a gg coo,_gg eEP r e F toN

2 0 2 2 5 7 2 0 6 6 3 6 2 1 = 6 ~ 8 s i n od iude ..... ' I;l.f' r, i..i'.',, ,,g.,l .' 0 t ...i. 4 ie 3 l V-De n nt oo s r n = o t ~ B i ~ m ~ i L ..... ' {l l'

i'.4,'

',. j ' i',,;t. .,_.i.'.' 0 2 l 3 o r o t n p o md e ut C Sc yd i ae r Bt Mt n Re c s jl ' ' 4.l'i i 0 r et ',;'.'i 0 r o ss, 3 L i D.s Ue t m i F R a IL r He e r B t u n t a e ~ r e ~ c p . i. ; '., -l. ' '.,.,... n 0 m

l

,.i,',, q,,,..' 8 e o 2 T C n o i n a t o r r u a t o S B . T ' ',. i,. '. ' _' S ......'l.; 0 ~ 6C ~ e 2R r o it m ) C F il 6 nd e o 8 p i d 2 ic t e lu e 3 t ( i r i e m it 1 i DN e it imp L 0 l,.i.'_'. x y mL ne ..i._., '.' 4 c r a oB 2 it iL pM l i n r u b m oy I g u d B a j u s g n loiS A M x - i e F S iB r t g eM R e i c r I o oL L n lo CHDU n

~..'

'l 0 l

'i*l,;i

.i, h

X 4 2

2 c e T e m o ta 0 0 0 0 m 0 0 m 0 0 0 0 O 2 0 0 0 0 s 0 s 0 5 0 5 a 3 3 2 2 r 1 1 F Eaa rooc.6.t-Q 8j c.ogo gE v )

A 2 0 3 5 272 0 6 6 3 6 2 1 n od e 6 it lud 8 S i e C De n nt R .ll..' l oo '..........'.....' 3 .i* 0 4 n r s o u Bis s r e V e m .l T..lL_.....* 0 .i*'i'_ _..'..........'...... ' 2 i T 3 t s-i m yd i a e L Mt c i g et r ss n ..... l T.. Ue =*l ,..'..........'......' 0 ) i xe R 0 1 ir L 3 F He ( Mu B t e a r I u L r t He a er p d m p m n e e aT T..; L_.....' .l ,....l 0 T 8 ~ 2 n y t n ~ i io o l t a i i r bt u u a t r a l ou S S t S a C l.. ^; L_..... ' Y. ' ' l '- 2 nS 0 R 6 o F) r 4 o 1 3 B ( y pt a m mim M. ei u TL d yty it n e m o m id ,L_.....' e lit i i i i i L t l u g il e .l_ 0 u c n b b 4 2 i ul n DN n lo oi M x I S Si ne s eM oB x r e r i a oL o i 4 g MCH B 1 o e lo r ,L_.....- n u .*e' l l. .'.........'.L. 2 0 2 h g c i e F ~ T ~ e m o t a 0 m 0 0 0 0 2 0 0 0 0 0 4 2 0 1 8 8 4 2 a 1 5 rF c>oI 7 <O O $ g n. E_p.

Framatoma Technologias Inc. 86-1266272-02 i Figure 15. Demonstration of Boron Dilution with DL RB-Sump Flow. Sump Delta Boron Concentration Limits. 3000 A ****,... 4...., Hu Moong umet i i i i 20 gpm at 25.0 hr ' E 2500 ------.-4-------'--------l--------F--,*,-l--------4---- r S l l l ^

A..

l 0 4 - Real Solubility Umit i c 2000 L-------i ----- s '------- -------- 1---- 4000, 2400, 3000 o i i e

",--------r'-..'.Ao*..-

U ppm CFT, RCS, i i i i J t 5 ---e-- bgg o 'Sa ua Sump-Delta

t-------t----

i i weoui o.p rw --3 .....i. - i i i n, i e a y 1000 - pe "--- 7-------'

p-----

,--------4---- - 0 Adjusted Core c. ...*A,, i i i 3 e i Solubility Umit E 3 500 hr----------------+'---- to , 40 hr i 0 e i i i 200 220 240 260 280 300 320 340 360 RCS Saturation Temperature,(F) Minimum Boron Solubility and HLI Mixing Time-Temperature Limits. 200 ~*--Max Solubility Temp 160 - ,--------d--

'-- ---- '-------------- --4--

y 160 ---------l---------l l l - - -l-- -*-Core Sofubility Umit 7------- $ 140

r'-----

-e-HU Mixing Umit 'g*-'120 t i i i I

l---------l----

---f--------f---- ---l------ --e-- Actual RCS Temp --J-- UO 100 --------i,-------,i i e i i 0.12 ft2 S8LOCA -/ r------- i---- --- ------ 1-- y 60.------_. e i e i m -,e i ,----- --,---- - --+--------- ------------ O 8 rL 60

'-------J------

L------ J------- L-------- g i i e i e i i E 40 -.------e,------- ,-------.9 ,I e i F: 3------- r-------- i i e i i i 20

n------

+-

w--------0------

--*--------s-------- 0 i 200 220 240 260 280 300 320 340 360 RCS Satur'ation Temperature,(F) APS and Dump to Sump Time-Temperature Effectiveness Limits. 120 --+--DHDL Dump to Sump i i i e i a Temp (266 r) g 100 T------ r-- T----- 7'--M-- A-Train LPI APS Ef6ctue i i i i e i 3 i i 1.0 ANS 71 i o e i e i e i E 60 - I l--- J----- L-- 1----- J. -e-B-Train LPI APS Effectwo I 'e 1.0 ANS 71 i i i i U l O 60 - A------ J,------ '--------7-- ---- ' ---- -J --m-Actual RCS Temperature + 012ft2 SBLOCA i i i i i i 5 e g 40 _-------+------ i i i i i

+--

--G-Maximum Solubility Temperature e i i p; 20 i -------5-------- 'l-E i i

r--

r----- --i-------i- ------ P i i i l i i i i i i e i e i i [ 200 220 240 260 260 300 320 340 360 RCS Saturatfor: Temperature,(F) 54 f l

t Framatoma Technologies Inc. 86-1266272-02 l Figure 16. Demonstration of Boron Dilution with APS Flow. l l l. Sump Delta Boron Concentration Limits. I 3000 i i A

- - - ,,...A....i HU Mixing Umit i

i i 6 gpm at 45.0 hr l E 2500 ---------l------- 'r - - - - - - - -l- - - - - - - - F - -,v J ',-l- - - - - - - - - - i ,9; 8 .A,.* l ^ 0. e - Real Solubihty Umit I C 2000-4000,2400, 3000 l i m e',** ppm CFT RCS, ) O t i i i t i 5

J-------L--,,,'.A g 1500-40 hr

--G-- ual Sump-Detta

-------,- g -- '--------j---.

Wthout Gap Flow 3 4.- i i i f 1000 -- - - - -,, y, * *, - - p - - - - - - - s' i '...*A 2^ 60 hr 6 ,--------4---.

Adjusted Core et i

i hr Solubility Umit E 10 hr i a 500-- - - - - - - - -.' - 3 50 hr 00 hr i i -- ----+ --+--------i-- i i l l l s 200 220 240 260 280 300 320 340 360 RCS Saturation Temperature,(F) 1 Minimum Boron Solubility and HLI Mixing Time-Temperature Limits. 200 --+-Max Solubihty Temp 180-------- a--------s-------- 6-------- 4-- y 160- --------I l l l l --M-Core Solubihty Umit $ 140 ---------l--------d--------

r'

--l------ --j-- -e-HLI Mixing Umst i i i e i i f f 120----------l--------J,------- 1---- s------ --J-- U .-e-- Actual RCS Temp o 100 --------i,-------,i i i 0.08 ft2 SBLOCA f r------ i y 80 -----------------.i .--------+------- - ------------ E-4 o i i i n. 60 - -------.'------- >i------- L------ L-------- e i i i E 40 --------.,-------,. i t b c-- i-3------- r-------- i 20 -

i-------

+-------

w--- ^. i n 200 220 240 260 280 300 320 340 360 RCS Saturation Temperature, (F) APS and Dump to Sump Tim' -Temperature Effectiveness Limits. e 120 i i i --+-DHDL Dump to Sump ',--.-----.,'-------r--------- + 100 ---------i Temp (268 F) i i g

,i i

r-l l l 1.0 ANS 71 _w -A Train LPI APS Effective E 80 ----------l--------f------- h- --e-B Train LPl APS Effective r g i i 1.0 ANS 71 O i i i i O 60 - --------. i e i -m-Actual RCS Temperature r------- i e i 0.08 ft2 SBLOCA E i e g 40 --+-Maximum Solubihty

l---

-- --{- Temperatura i g i_. i i p 20 - - - - - - - - ^ - - - - - - - ' - .---;2- --l------ -------l-------- i i 0 200 220 240 260 250 300 320 340 360 ( RCS Saturation Temperature,(F) 55

Framatoma Technologi:: Sinc. 86-1266272-02 l Figure 17. Demonstration of Boron Dilution with HLI Flow. Sump Delta Boron Concentration Limits. 3000 HU Mixing Limit i e i i e $ 2500

l------- '--------l--------h----

,.d*#-* 200 gpm at 4,0.0 hr ch r ~~ ' ' ~ ' cb , ',.**a ^ 4 RealSolubihty Umit 2000 ---------l--------,

- 4*-----

1---'

4000,0,3000 ppm , i u s i CFT, RCS, BWST c i g 1300 --------3-------,'------ j...* i o , - - - - g-l- - - - - - - - j - - - - ---e--- Actual Sump Delta 3 winouto.pr w e i i i i e 30 & instant Sump Conc o 1000 c _-------a-------4.*------8

Adjusted Core a.

20 hr i g 600 .- y,4. : Solubihty Umit e

{

a --- ---. e o i l , 350 hr s hr, i 0 200 220 240 260 280 300 320 340 360 RCS Saturation Temperature, (F) Minimum Boron Solubility and HLI Mixing Time-Temperature Limits. 200

a;-------*,--------w,

-+-Max Solubility Temp 180 y 160---------,,--------;l --4-- l

l l

--15-Core Solubility Limit 3-- $ 140 ---------l--.-----d------- --j-- --0-HU Mixing Limit e i 1 i 120-e )

8--------J,------ --'------- '----

--8------ J-- - Actual RCS Temp O 100 - -------- -------,. ------- r------- i i i i 0.08 ft2 SBLOCA 8 e 1 T-- i j; to ---------e.--------.--------+--------i-

w-----

i e i e i E-4--------e-------- O Q. 60

'-------J,-------1------

.b - J,------- L-------- i E 40 ---------l--------4------- i

l------ --4------- r'--------

F: i 20 i i i y, 7

+--------w-----

--4--------o-------- i 0 200 220 240 260 280 300 320 340 360 RCS Saturation Temperature,(F) 1 APS and Dump to Sump Time-Temperature Effectiveness Limits. 120 , -+-DHDL Dump to Sump i i a $ 100 ---------}--------l--------l-------'i Temp (286 F) i e r ' -----h----- -$ -M-- A-Train LPI APS Effix:tive 8 2 1.0 ANS 71 60 --------1------J-------'-------L- ~ 1----- J -e--B-Train LPI APS Effective g l l l 1.0 ANS 71 U Q 60 - J

4-------J-------i-------

--al-Actual RCS Temperature e i i e A- -J .L O.08 ft2 SBLOCA i i e i i i eg 40 ---------+i i i i e -Maximum Solubility

l----

- ---+-- - -1 Temperature e E p 20 ::-------e------- r----- -,-------i-------- t r' a i i e a 0 _ i i ~ 200 220 240 260 280 300 320 340 360 RCS Saturation Temperature,(F) 56

Framatome Technologias Inc. 86-1266272-02

6. Confirmation of Boron Dilution via Sump Concentration Measurements Once an active boron dilution method has been initiated, a positive confirmation that it l

Is effective can be obtained by continuous monitoring of the sump boronometer. The amount of time required to obtain feedback regarding effectiveness of dilution is a function of which active boron dilution method is used. Calculations were done to } examine the time that it takes to obtain changes in the boron readings at the boronometer for the APS, DL RB-sump, and HLI boron dilution methods (Ref. 8). The boronometer at CR-3 is located near the ECCS sump suction piping. For the APS method, the time it takes liquid to reach the boronometer includes the time to fill the pressurizer, the time for the concentrated boron to traverse the lower plenum and downcomer, and the time it takes to make its way from the break to the boronometer. The calculations demonstrated that feedback could be obtained before approximately 9 hours plus the time it takes to process the sample from the boronometer. 1 For the DL RB-Sump method, the time that it takes the boronometer to register a change in the sump concentration is dependent upon the valve open area and the hot leg pressure. The longest time to register is consistent with the smallest opening and the lowest hot leg pressure (gravity feed post-LBLOCA). The shortest time is consistent with the maximum opening and the highest hot leg pressure. The calculations demonstrated that _ feedback could be obtained as quickly as three minutes, but no later than nine hours, plus the time it takes to process the sample from the boronometer. For the HLI method, the time that it takes the boronometer to register the concentration change is shorter than the APS because there is no filling time and the excess flow rate is much higher. The calculations demonstrated that feedback after initiation of HLI 'should be obtained between approximately 2.5 and 6.5 hours plus the time it takes to 1 57 i

Framatoma Technologias Inc. 86-1266272-02 process the sample from the boronometer. (Note: When using HLl it is possible to subcool the core exit fluid, either continuously or cyclically.) l l The material ir) this section is provided to highlight the fact that positive feedback of core boron dilution will not be instantaneous. Somewhat continuous moriitoring of the sump boronometer is required both prior to and after the active mechanism is initiated to verify that dilution is occurring. It also highlights that cyclic or continuous core exit subcooling may be observed following the use APS and HLI, although it is most likely with HLI because it provides the highest flow rate into the upper plenum region. I I 58

Framatomo Technologies Inc. 86-1266272-02

7. Summary and Conclusions This report summarizes boron concentration control methods and calculations needed for the CR-3 ' plant to meet the NRC requirements for -post-LOCA. core boron

^ concentration control. Specifically, the active boron dilution methods available at CR-3 were summarized, calculations to demonstrate compliance to Criterion 5 of 10 CFR 50.46 were provided, post-LOCA boron concentration control guidance suitable for l Technical Support Center use was defined, and the time ranges over which changes in the sump boron concentration would be observed following initiation of an active dilution method were quantified. i The compliance calculations demonstrated that CR-3 can meet Criterion 5 of 10 CFR 50.46 by having at least one active dilution method that can be initiated prior to reaching the solubility limit when a decay heat of 1.2 times ANS 1971 was used. These calculations used revised core mixing volumes to define limiting times without credit for RVW overflow or gap flow. The DL RB-sump method was shown to be effective at lower RCS pressures, but the method cannot be used at higher RCS pressures because of potential sump screen damage. The flow rate that can be provided to the core via APS, limits the time post-trip that it is effective, but it has been shown to be adequate to cover the pressures above which the DL RB-sump method can be used. Considered together, at least one of the methods can be effectively established prior to the core reaching the solubility limit. This combination of methods meets the requirement to have an active boron dilution mechanism that is effective over any RCS pressure range that core boron dilution could be needed. ~ The TSC guidance includes a method for determining when and what form of active boron dilution can be used based on RB mixed-mean to sump boronometer measurements, RCS saturation temperature from the average of the core exit thermo:,ouples, and time post-LOCA. The preferred dilution method is via APS, because this method does not require an LPI pump to be shutdown. The guidance is 59

1 Framatomo Technologics inc. 86-1266272-02 i comprehensive in that it provides information for Ose with and without sump boronometer indications. In the event that the boronometer is unavailable, time and saturation temperature can be used to initiate active boron dilution methods, i s l 1 e e 9 60 l

U.S. Nuclear Regulatory Commission Attachment C 3F0498-17 Page 1 of1 ATTACHMENT C ACRONYMS AND ABBREVIATIONS APS...... Auxiliary Pressurizer Spray (mitigation method) BWOG..... B&W Owners Group BWST..... Borated Water Storage Tank CFT...... Core Flood Tank CR-3...... Crystal River Unit 3 DIeRB Sump. Drop Line to Reactor Building Sump (mitigation method) ECCS..... Emergency Core Cooling System ES....... Engineered Safeguards FPC...... Florida Power Corporation FTI....... Framatome Technologies Incorporated gpm...... gallons per minute HLI-RF.... Hot leg injection via Reverse Flow (mitigation method) HPI... ... High Pressure Injection system LAR...... License Amendment Request LBLOCA. . Large Break LOCA LOCA.. .. Loss of Coolant Accident LPI....... Low Pressure Injection system MCC...... Motor Control Center NRC...... U.S. Nuclear Regulatory Commission ppm...... parts per million RB....... Reactor Building RCS...... Reactor Coolant System RV....... Reactor Vessel RVVV..... Reactor Vessel Vent Valve SBLOCA... Small Break LOCA TSC...... Technical Support Center 1 l L}}

ML20217G699

Text

SUBJECT:

SUMMARY

SUMMARY

SUMMARY

SUMMARY

SUMMARY

A A

Navigation menu

Search