ML20203F079
| ML20203F079 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 12/11/1997 |
| From: | Klingenfus J, Seals J FRAMATOME |
| To: | |
| Shared Package | |
| ML20203F070 | List: |
| References | |
| 86-1266272, 86-1266272-00, M-97-0146, M-97-0146-R00, M-97-146, M-97-146-R, NUDOCS 9712170277 | |
| Download: ML20203F079 (43) | |
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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: l coC.c rec toCuuEm oEmrc.AteN eoMatm Rrv system:n tof At eActs TR ANsMT*Eo M-97 0146 0 RCS,DH #3 mE Post-LOCA Boron Concentration Management for CR 3 l l l KWDs (IDEmFY FEYwORDs 8oR LATER RETRirYAL) hot lea injection, decay heat drop line, precipitation DKREF (NETERENCEs oR FILES . LIST PRIMARY FILE hrs 7 86 1266272 00 WEND (VENDOR NAMQ VENDOR DOCLF 'Erfr NUMBER (DKREF) SUPEftE2DED DOCuMCms (DAREF) FTl 86 1266272-00 N/A
.PN Y-42 ~45 1 0 l I l l l l l ll l l l COMMENTS (USAGE REsTRICTONS. PROPRIET ANY, ETC )
NOTE: . Use Tag number only for valid tag numbers (t e., RCV 8. SWW34, DCH-99), otherwise, use Part number field (i.e., CSC14599, AC1459). If more space is required, write *See Attachment" and list on separate sheet.
FOR RECORDS MANAGEMENT USE ONLY *
- Quality Record Transmittal received and inform. tion entered into SEEK.
Entered by: Date (Return copy of Quality Record Transmittal to NOE Sup ort Specialist.) DEsoN ErciNCER MUM.4 w DATE VERFICATCN EN3INEER DATE NUCLEAR ENO DATE f N' U/tt/9/ U// GL. cc: Nuclear Projects (if MAR /CGWR/PEERE Calculation Review form Part lit actions required Oves TNo Return to Service Related) O ves TNo (If ves, send copy of the form to Nuclear Regulatory Assurance and a Supervisor, Config. Mgt. Info, copy of the Calculation to the Responsible Organizationtsi identified in Mgr., Nucl. Operations Eng. (Original) w/ attach Part til on the Calcu'.c. ion Review form.) 9712170277 971213 PDR ADOCK 05000302 p PM
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P:st LOCA Boron Concentration Management for CR 3 O Non Safety Folated - i uanwCowicar uweta i n/a I i v Noon ocewsNr wwera i 86 1266272 00 APPROVAL PRINTED SIGNATURES NAME 1 Design Engineer 7stg pf'Jpu/O V. M. Esquillo i Date 12/12/97 Verification Engineer N/A ! Date . Supervisor - 2f ^- R. W. Knoll Date /s//J/77 12/12/97 ft(MS MtVibtD N/A PUM8'Qbt bVMMAMV The purpose of this esiculation 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. These methods are predicated on betng able to induce , a dilution flow to prevent boron nrecipitation. The first involves opening the decay heat drop line (DHDL) to the sump the second is to refill the RCS by the auxiliary spray, and the third is hot leg injection via reverse flow ! through the DHDL. AtEvi.15 GOMMAmv The outcome of the effort consists of proposed EOP/TSC guidance for boron management. This guidance is based on inferring the core boron concentration from the measured sump concentration. The premise is that if boron is depleting in the sump, it must be concentrating in the RCS or core. Figure 11 shows the !!rn; to reach the solubility litait as a function of uncertainty adjusted temperature, as well as the times at which APS is cffective. Figure 12 provides the necessary guidance for ensuring that the solubility limits are not challenged i using the hot leg injection and dump to sump methods. Absent sump concentration measurements, a time based guidance based on Figure 13 is provided. This guidance constitutsc a means of effectively managing the boron concentration in the RC3. i
O CALCULATION REVIEW (v . ....... ...M _ Page 1 ofg, CALCV.ATION DdQ.Atfif. M 97 0146 Rev 0 7ARTI DESIGN ASSUMPTION / INPUT REVIEW: APPLICABLE 6 Yes O No The following organizations have reviewed and concur with the design assumptions and inputs identified for this calculation: f p ofr/t? Nuclear Plant Technical Support 4'. u ^1 System Engr 5"***" Nuclear Plant Operations 7 OTHtet(si 69*** **f wo,.. .... s- . .. PART 11 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 resultc. Nuclear Plant Technical Support System Engr sww. Nuclear Plant Operations s._. ._ y
& 4 =4 .
h Nuclear Plant Maintenance O Yes @ N/A Nuclear Licensed Operator Training C Yes @ N/A Manager. Site Nuclear Services O Yes @ N/A Sr. Radiat'on Protection Engineer (?,jN/A '"***" O Yes Nuclear PlagEOP Group
@ Yes O N/A sco.m N! M OTHER:
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3 ca.cuutem warv. M 97-0146 Rav 0 PART 1 - 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: j(ff$yg Nuclear Plant Technical Support [,4. If4 / 2.!/t !17 HWfb /f System Engt Wf* ///f ' Nuclear Plant Operations & Wl8dW M ' ' mmarsi 5*='<*o**' s, i . o 6,=w. o PARTll- 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 t mplemeat the results. 3F Nuclear Plant Technical Support - . CW[/lh7
/2- -
System Engr 6"*
- P" W '
Nuclear Plant Operations 4 w M '#"* & s,wi .m.4 Nuclear Plsnt Maintenance O Yes G N/A Nuclear Licensed Operator Training O Yu @ NM Manager, Site Nuclear Services O Yes @ N/A Sr. Radiation Protection Engineer O Yes @ N/A Nuclear Plant EOP Group B Yes D N/A s, M .o..M **"v 3WP PP - - OTHER: 5,=w.o.. Aev 1217
* @ CALCULATION REVIEW Pagegot/
r3 CALCVtATiON NO lhsV.
,H.91-o/Je #n'56 PART lli CONFIGURATION CONTROL: APPLICABLE Yes @ No The following is a list of Plant procedures / lesson plans /other documents and Nuclear EnpMeering calculations which require updating based on calculation results review: l Document Date Reavited Responsible Oraaniention Upon completion, forward a copy to the Manager, Nuclear Regulatory Assurance Group for tracking of actions if cny items are identified in Part lli, if celculations are listed, a copy shall be sent to the original file and the i calculation log updated to reflect this impact.
PART IV - NUCLEAR ENGINEER!NO DOCUMENTATION REVIEW ' The responsible Design Engineer must thoroughly resview the below listed documents to assess if the calculation requires revision to these documents, if "Yes,* the change authorizations must be listed below and issued concurrently with the calculation. Enhanced Design Basis Document @ves O No (tC'l 779,712718 Vendor Qualificaticn Package rV0'8' ) FSAR 3 ves O No ww8) Uf HI Topical Design Basis Doc. O ves dNo ffC81 ' Improved Tech. Specification O ves G No iL'"*8' E/SOPM O ves UNoiTcai tmproved Tech. Spec. Cases @ ves 3 No (L*"*'l /R D J ther Documents reviewed: Config. Mgmt. Info. System O ves O No Icio O ves O No ice =a poc meant =co Analysis Basis Document Oves 7NoFC'> 0 ves O No ice =ut poc metat=cti Desiqn Basis Document OvesTNoffC5 C ves O No icm=u poc munt=ce. Appendix R Fire Study 0 ves E No FCa O ves O No ecumu ooc mn==co Fire Hazardous Analysis O ves hNo E O ves O No icm=w poc aestw=co NFPA Code Conformarco Document O yes e No FC O ves O No tCM=ut doc NFtM=co PART V - PLANT REVIEWSIAPPAOVALS FGH INSTRUMENT SETPOINT CHANGE PRC/DNPO approvalis required if a setpoint is to be physically changed in the plant through the NEP 213 process. PRC Review Required O Yes d No /Date PRC Chairman DNPO Review Required Yes @ No DNPD /Date Dt%4NINGWtt%DAfE ogsiGN tNGNttR PMtNTED DeAME
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SUMMARY
SHEET (CSS) I.M M o D DOCUMENT 'DENTIFlER 86 1266272 00 TITLE Post LOCA Boron Concentration Management for CR 3 ! PREPARED BY: REVIEWED eY: NAME J A Klingenfus NAME J C Seals slGNATuRE . v stGNATURE TITLE Su rvisory Engine [ DATE /g///c/p TITLE Supervis.ory Engineer DATE jfjjh COST CENTER 41010 REF. PAGE(s) 5 TM STATEMENT: REVIEWER INDEPENoENCE, purpose AND
SUMMARY
oF REsuLTs: This r: port summarizes boron concentration control methods and calculations needed for the CR 3 plant to meet the commitment to the NRC via FPC letier 3F1297-12. Specifically, the active boron dilution methods available at CR 3 were summarized, calculations to demonstrate compliance to Criterion 5 of 10 CFR 50.46 wera provided, post LOCA boron concentration control guidance suitable for Technical Support Center use was d fined, and the time ranges over which changes in the sump boron concentration will be observed following initttion 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 one cetive 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 cr:dit 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. Tha flow rate that can be provided to the 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 cffsetive over any RCS pressure range that core boron dilution could be needed. Tha TSC guidance included a method for determining when and what form of active boron dilution can be used bas:d on RB mixed mean to sump boronometer measurements, RCS saturation temperature from the average of the core exit thermocouples, and time post LOCA. The preferred dilution method is via APS, because this m:thod does not require an LPl pump to be shutdown. The guidance was comprehensive in that it provided information for use with and without sump boronometer indications. In the event that the boronometer is unavcilable, time and saturation temperature can be used to initiate active boron dilution methods. THE FoLLoWING COMPUTER CooEs HAVE BEEN usED IN THis DOCUMENT: CODE IVERsioN l REV CODE IVERstoN t REV THis DOCUMENT CoNTAINs AssuMPTloNs THAT MusT BE VERIFIED prior To usE oN SAFETY RELATED WORK YEs ( ) No ( *) PAGE 1 OF 38
. Framat:me Technologbs Inc. 86-1266272-00 Record of Revision Rev.No. Chanae Sect / Para Description /Chanae Authorization 00 Initial release, December,1997. 2
. Frematome Techn:logi:s Inc. 86-1266272-00 I
i
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i LTable of Contents l 1 i List of Ta bles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . List of F ig u res . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
- List of Refe rences . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..1.
- I
- 1. I NTR O D U C T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
l
- 2. ACTIVE BORON DILUTION METHODS .................................................................... 7 [
2.1 DECAY HEAT DROP LINE DUMP TO SUMP (DL RB-SUMP) ..............................l........... 8 4 2.2 PRESSURIZER AUXILWRY SPRAY FLOW FROM THE LPI PUMP (APS) .........................10 .
.: 2.3 HOT LEG INJECTION Va REVERSE FLOW THROUGH THE DHDL.................................11 j 1
-3. COMPLIANCE TO 10 CFR 50.46 REQUIREMENTS............................................... 23 4 1
- 4. EOP GUIDANCE FOR POST-LOCA BORON DILUTION ........................................ 28 4.1 MINIMUM TIMES FOR ACTIVE BORON DILUTION WITHOUT SUMP BORON SAMPLING ..... 28 :
4.2 SUMP BORON CONCENTRATION METHOD FOR USE IN TSC GUIDANCE ..................... 29
- 5. CONFlRMATION OF BORON DILUTION VIA SUMP CONCENTRATION i
M EA S U R E M E N TS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .;
- 6.
SUMMARY
AN D CON C LU S IO N S . . . .. . . . .. .. .. . ... . . . . . ... .. . . .. .. .. . . .. . . . . .. . .. . ..... .. ..... ... .. .. . .... . 37 i n k i i i i 4 I 9
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. Frcm; tom]Yechnologi:s Inc. 86-1266272-00 l
List of Tables Table 1. APS Flow Rates and Time to Fill the Pressurizer., .......................................13 l Table 2. APS Matchup Times for B-LPI Pump Operation............................................14 i Table 3. APS Matchup Times for A LPl Pump Operation............................................14 Table 4. Minimum Solubility Time vs RCS Saturation Temperature and Pressure l with 1.2 AN S 1971 De ca y He at. .............. ... ......... ................... . . .................. . 2 6
- List of Figures '
Figure.1. CR 3 DHDL Dump to Sump Flow Patterns with the A-LPI Pump.................15 Figure 2. CR-3 DHDL Dump to Sump Flow Patterns with the B LPI Pump.................16 Figure 3. CR-3 Pressurizer Auxiliary Spray Flow Patterns with the A-LPI Pump. .......17 Figure 4. CR 3 Pressurizer Auxiliary Spray Flow Patterns with the B-LPI Pump. .......18 Figure 5. CR 3 DHDL Hot Leg injection Flow Patterns with the A-LPI Pump..............19 Figure 6. CR-3 DHDL Hot Leg injection Flow Patterns with the B-LPI Pump.............. 20 Figure 7. APS Effective Boron Dilution Time Without Gap Flow (2568 MWt at 1.2 AN S 1971 De ca y H e a t) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Figure 8. APS Effective Boron Dilution Time Without Gap Flow (2568 MWt at 1.0AN S 1971 Deca y H eat) . . . . . . . . . . .. . . . . .. . . . . .. . . . . .. . .. . . . . .. .. . . . .. . . .. . .. . . . . . . . . . . . . . . . . . . . . 22 Figure 9. Core Mixing Volume Versus Time at 2568 MWt and 1.2 ANS 1971. ........... 26 Figure 10,2568 MWt Matchup Times and Times to Solubility without Gap Flow or Active Boron Dilution with 1.2 ANS 1971 Decay Hest. ........................... 27 Figure 11. Matchup Times and Temperatures for Active Boron Concentration Control (2568 MWt with 1.0 ANS 1971) ...................................................... 33 Figure 12. Core Boron Concentrat!on Control Limits................................................... 34 Figure 13. Minimum Boron Solubility and Mixing Limit Time versus RCS S atu ration Tempe ratu re. . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5 4
. Frcmat::me Technologbs Inc. 86-1266272-00 List of References 1.* FPC Calculation S96-0134 Rev.1,
- Fluid Velocity Analysis for the Reactor Building Sump Screens."
- 2. FTl Document 32-1266221-01, *DHDL R5 Analyses for Boron Dilution," 12/97.
- 3. FTl Document 32-1266263-00,
- Sump Delta Method for CR-3," 12/97.
- 4.
- Interoffice Correspondence, S. K. Balliet to K. R. Campbell #NOE97-2331 dated 11/11/97.
- 5. FTl Document 32-1266110-01, *B&WOG Post LOCA Core Boron Dilution."
6.* FPC Calculation M97-0097, Rev.1, ' Low Pressure Auxillay Spray Flow Rate for Boron Precipitation."
- 7. FTl Document 51-5000519-03, " Boron Dilution by Hot Leg injection."
- 8. FTl Document 32-1266110-00, *B&WOG Post-LOCA Core Boron Dilution," 4/17/97.
- These docurnents are maintained and controlled by Florida Power Corporation. Per FTl procedures, use of these references are allowed in safety grade calculations with tb3 approval of the cognizant unit manager or contract manager. The signature below authorizes the use of these documents for input to this evaluation.
1/ N Nb7 (Unit Ma' nager / Contract Manager) (Dafe) 4 5
Framatome Tcchnologi s Inc. 86-1266272-00
- 1. Introduction Post-LOCA boron concentration control is a Nuclear Regulatory Commision (NRC) restart issue for CR-3. Florida Power Corporation (FPC) has committed to the NRC to provide calculations to support license amendment request (LAR) #223, which describes their approach to the boron concentration control. Framatome Technologies incorporated (FTI) has performed and documented 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 via FPC letter 3F1297-12. It summarizes the active boron dilution methods available at CR-3, provides calculations to demonstrate compliance to 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) and the drop line to the reactor building (RB) sump (DL RB-Sump) as active boron concentration control mechanisms. The calculations demonstrate that at 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 core 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.
6
. Frcmatome Technologics Inc. 86-1266272-00
- 2. Active Boron Dilution Methods Post-LOCA core boron concentration control is provided by any active or passive mechanisrn that results in a net liquid flow through the core. The passive mechanisms are reactor vessel vent valve (RWV) liquid overflow, hot leg nozzle gap liquid recirculation, loop refill, and boton carryover in steam. The active methods are initiated and controlled by operator actions. The viable 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.
There are two other potential boron dilution methods available at CR-3 but have not been validated for use. The first is decay heat drop line flow through a restricted flow bypass line into the sump or into the suction of an operating LPI pump using valves DHV-120 or DHV-121. This method could lead to NPSH concerns with the operating LPI pump or cause a water hammer transient if used under the wrong conditions. The second method is the APS flow via flow from the high pressure injection (HPI) pump. This alignment does not require termination of an LPI pump, but it does require long-term operation of an HPl pump. The main limitation of this method is that its initiation is based on manual opening of valves in a region that may or may not be accessible due to dose rate restrictions post-LOCA. This method has not been validated for use at CR-3, because the flow delivery rates have not been qualified, although estimates suggest that flows of approximately 100 gpm may be achievable. 7
. Frcm:toma Tcchnologi::s Inc. 86-1266272-00 The three viable dilution methods: DL RB-sump, APS from the LPl pump, and HLI have been analyzed and shown to be viable boron concentration control methods at CR-3.
The plant configuration required for use of each method and the equipment availability needed for each is described in the following sections, l 2.1 Decav Heat Drco Line Dump to Sumo (DL RB-Sumo) l 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 that of the sump. The LPI / HPl 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 and backward through the non-operating LPI pump suction line into the sump. This dilution method is currently available at CR-3 via the piping configuration and flow patterns as provided 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 it prevents debris in the RB from entering the sump and being entrained into an operating ECCS pump that takes suction from the same sump. The liquid velocity limit that protects the integrity of the sump screen is 30.5 ft/s (Ref.1). A 8 l
. Frcm; tome Tcchnologi::s Inc. 86-1266272-00 RELAPS analysis performed by 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. 2) without exceeding the velocity limit of 30.5 ft/s.
There are two methods available for determining the hot leg pressure. There is a I pressure tap located in the vertical pipe of the hot leg that directly reads the RCS pressure. This pressure tap has an instrument uncertainty that is too large to be used to determine when the DHDL could be opened. There are also sixteen qualified incore thermocoup.es 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 known. An average of a minimum of eight incore thermocouples using the plant computer results in an uncertainty band of +9.0/-19.25 F of indicated minus actual temperature (Ref. 4). 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 - 19.25 = 286.52 F or a saturated pressure of 54 psla. If the DHDL is opened , at this temperature, the actual conditions could be as low as 286.52 - 9 = 277.52 F, which coincidos with a minimum pressure of 47 psia. Therefore, the DHDL can be opened when the average of eight exit thermocouples is 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). This steam that flows into the sump should not be drawn into the intake of the operating LPl 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. 5). 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 l 9 L y t
9 . Frcmatom] Tcchnologi:s Inc. 86-1266272-00 the DHDL should be isolated immediately to protect the lone operating LPl pump. A different dilution method should be used if available,if not, reactivation of this method at a later time could be more successful. 2.2 Prossurizer Auxiliary Sorav Flow from the LPl Pumo (APS) The APS dilution method is currently available at CR-3. The piping arrangerrients and flow patterns are shown in Figure 3 and Figure 4. 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. 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 flovt rates. After the spray fills the pressurizer it begins to flow into the hot leg and finally to the core region. If the spray flow exceeds the core bolloff rate, the ewess flow will raise the level in the hot leg and upper plenum. The reactor vessel manometer between the downcomer and core regions will not support the higher level in the upper plenum. As a result, a small but somewhat continuous 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 cc,ncentration control when the boron outflow exceeds the boron inflow from the pressurizer spray. The core boiloff concentrates any boron in the spray. When the excess s;. ray flow carries out more boron than is concentrated in the core, a long-term dilution mechanism is achieved The minimum available spray flow as a function of RCS pressure (Ref. 6) is showr: on 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 used these flows to calculate the time at which the pressurizer auxiliary spray flow matches decay , heat and the time at which it provides an excess flow of six gpm such that boron dilution 10 1
. i
. Fram::toma Tcchnologins Inc. 86-1266272-0C is achieved (Ref. 5). Table 2 providos the decay heat matchup times and effective boron dilution times for spray flow provided by the B LPl pump considering 1.0 and 1.2 times ANS 1971 decay heat. Table 3 provides the same information for spray flow i provided by the A-LPI pump. This information is presented graphically in Figure 7 and Figure 8. These results 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 bypass some portion of the spray flow. However, if the gap flow is sufficient to bypass 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. 2.3 Hot lea inlection Via Reverse Flow Throuah the DHDL The DHDL can also be used to inject liquid int i the hot leg to initiate a net core reverse flow with discharge through the cold leg pur.p 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 HLl, the LPI cross-connect line must be opened and have a qualified flow indication, the operator must throttle the normal LPI flow to the core flood tank (CF1) nozzle, and the decay heat drop line valves must be opened to the RCS. Flow travels backwaH through the inoperable LPI pump. This method is currently avaliable for CR-3 pending NRC review and approval. The piping arrangements and flow patterns 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. 7). The results indicate that the hot leg injection alignment must provide flow for one HPl pump (~600 11
l l
. Frcmatoma Technologins Inc. 86-1266272-00 .
l gpm), a minimum hot leg injection flow of at least 500 gpm, and approximately 1000 gpm flow through one CFT nozzle. 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 I 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 l uncertainties. The drawback of this method is that it requires one LPI pump to be deactivated, and the 1 method must be initiated prior to exceeding the hot leg mixing limit described in Section
. 4. The required ECCS flow alignment is also unusual and complex in that the flow from the lone operating LPI pump must provide flow to an HPl pump and the remaining flow is split between the one CFT / LPI nozzle and the DHDL. The operator must throttle valves in the ECCS system to provide the targeted flow spic necessary to ensure adequate core cooling and provide adequate boron dilution via reverse flow through the Dh0L.
I i b i 12
- . - - . - - .. ... - - . . - . - = - .
. Frcmatoma Technologics Inc. 86-1266272-00 Table 1. APS Flow Rates and Time to Fill the Presturizer B-LPI Spray bow A-LPI Spray Flow l Pressure Flow Rate Fill Time Flow Rate Fl'l Time (psla) (gpm) (hr) (gpm) (hr) i 14.7 114.5 1.73 125.5 1E7 35 102.8 1.92 114.7 1.72 45 97.0 2.04 109.4 1.81 60 86.4 2.29 100.1 1.97
' ~
75 75.8 2.61 9O 7 2.18 105 46.3 4.27 67.'S 2.94 Note: These flows were calculated with throttled LPI flows and the assumed flow spliu of 600 gpm HPl and 1600 gpm LPI flow from either the A- and B-LPI pumps. This maximum flow is assured by throttling the LPI flow to an indicated flow of 1100 to 1300 gpm. 13
. Fram;toma Tcchnologbs Inc. 66-1266272-00 l Table 2. APS Matchup Times for B-LPl 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 (psla) (gpm) (br) (hr) (br) (br) 14.7 114.5 17.2 20.6 31.4 38.3 36 102.8 24.7 30.3 45.0 53.6 45 97.0 30.6 37.5 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 Table 3. APS Matchup T.imes 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 (psia) (gpm) (br) (br) (hr) (hr) 14.7 125.5 12.5 14.4 21.7 25.8 35 114.7 16.1 19.2 29.4 35.E 45 109.4 18.9 22.5 35.0 41.7 60 100.1 26.4 32.2 47.8 56.4 75 90.7 38.3 46.4 64.7 75.8 105 67.3 93.9 112.8 147.8 181.7 14
Framatome Technologies Inc. 86-1266272 00 Figure 1. CR-3 DHDL Dump to Sump Flow Patterns with the A-LPI Pump. Ilot Leg {RB DlIV-3[ { ouv-4X i m l' x l DIIV41 . l Y ToIIPI To PZR Aux Spray
- l. )N
, r l 3 7 DIIV-II j g DlIV-34 J '
DilP-lA DlIV-Il0 DlIV-5 {. DlIV-42
?
Fx w w N m -
" DEI-t-FEl J *g Mw "
- To CFTNozzle i DlIV-39' bDIIV120 I b #
' l ! Dh-38 . '
RB Sump ; 9 s L DlIV-40 : DII-t-FE2 J T DIIV-43 LJ V
- ToCFTNozzle D IV-Ill Dl W
; DIIV-351 y
] {DIIV-12 -
TollPI From BWST 15
. 6 _ 1 _ l e l e z z z z o o
. N N p i r
i r m c U _ o o u T T P ; : I P y L- 5-y B a p r W l D E ' e S x F- _ ht u 8 3-ht Aksj R I U D I I Z ' i P o J 0 w T 0- s 2 n r , M-7 e 1 2 t 1 1 i
- I 6 t N-i 6 a I D 2
1 P I P D I P I rL I I 6 w I o ,J 4 o 8 l o T f
)
T F g p f
] ~
> I I
I
} 3 '
m g r u . S _ o 1 4 I t p NlW-D - 0 2 1 1 2 1 B 1 P-m [ n- w u T i D m[ l i D T D S W S W L B { 9 3 PL B D m ' 'J m o o 4 V- 5 H r F 3 N-I I D 3 V r T D . I D I I c n 3 2 4-3 4-eD I s R- > V I V I C I I e B D D i I:l' R g l.!' .l!! l' , l * ; ' l o 2 g e o h n e r l l t o X g c u g I 3 4 p e W- V-I e T i F I D I D S e B R m t o a m e r F
Frcmatome Technologies Inc. 86-1266272-00 - Figure 3. CR-3 Pressurizer Auxiliary Spray Flow Patterns with the A-LPI Pump. Note: The B-LPI Train Operation is Optional. Hot Leg l {RB DlIV-3] [ f i DlIV-4] { l l kJ l r1
! DHV-41 .
l From BWST j To HPI To PZR Aux Spray
$ A )
-11 I
DilV-34] ( DlIP-1A DilV-110 ' DlIV-5 & y : o CFTNozzle
; DH-1-FE1 7 {pygy.g l )DIIV,9] -[:: DIN-120 J RB Sump I (Dif-38-FE l DIIV-43 " > >: To CFTNozzle '
m
,l -> DIIdh
{
~
l DHV-35] To HPI From BWST
- 17
Fr:matome Technologies Inc. 86-1266272-00 - Figure 4. CR-3 Pressurizer Auxiliary Spray Flow Patterns with the B-LPI Pump. Ilot Leg {RB DIN-3] { { DHV-4] { ! LJ
- F1
} DHV-41 '
l From BWST To HPI To PZR Aux Spr.y l "
- J
^
"II DIN-34] { . DHV-110 J
DlIV-5
; DIN-42 A gj g v gj
' LJ '
FT m r7 : To CFT Nozzle i FT RB Sump DHV-39] [:
- DiW-120 DH-38-FE
; l l
. J u
! DlIV-43 Dtw-121 ) m E y n : ToCFTNozzle
{ > DlIP-1B
~
jRB P DIIV-35' -
- J L y To HPI
. From BWST 18
Framatome Technologies Inc. 86-1266272-00
' ~
Figure 5. CR-3 DHDL Hot Leg Injection Flow Patterns with the A-LPI Pump. Ifot Leg i lRD DlIV-3[A :
- f DlIV-4 l 2 .
l DlIV-41 l From BWST l ToIIPI To PZR Aux Spray I k DlIV-34] [ DlIP-1 A DlIV-110 DlIV-5
- To CFTNozzle
; y - 7 Dii-1-FEl pity.g r DIIV-39] [ uDfiv-120 N , g RD Sump l - p j (Dii-38-FE DIIV-7 DlIV-40 ;t DH-1-FE2
" : To CFTNozzle m V3 I' '
- l. DlIV-111. DIIV-6 Dil -1 ' PDIIV-12 lRD -
l DHV-35] [ k ToIIPI From BWST gg
Frcmatome Technologies Inc. 86-1266272-00 Figure 6. CR-3 DHDL Hot Leg Injection Flow Patterns with the B-LPI Pump. Hot Leg t lRB DlIV-3[ A ,!
- DlIV-4{ !
l e N 2 m l DlIV-41 . l From BWST To IIPI To PZR Aux Spray l l
. M r , r "U
!' DlIV-34] [ DIN-lio Jk J k DHV-5 lDIIV-42 .
I LJ ,
; To CFTNozzle r i PT ,
DlIV-39 t DIN-120 M I RB Sump - > (Dif-38-FE
! DHV-43
-12 > Di m n % : To CFTNozzle
,' ) DHP-IB DlIV-35J' P
~
k To IIPI From BWST
. 20
Framatome Technologies inc. 86-1266272-00 i Figure 7. APS Effective Boron Dilution Time Without Gap Flow (2568 MWt at 1.2 ANS 197_1 Decay Heat). 80 , 4 60 -------- --------- ------- .---------.--- --- 4- ------ *-------- *---- ----*--------- g , e g
. . i . . .
e. 40 .---------;-___----- ,--- _---. ,-_--------;-----_---q---------3---------p---------;.-------- u , . . . . . e . . . . . n . . . . . . w ot . . . . . . . . l l l l l -dD-A-LPI - Pzr Aux Spray ENective 20 -------- ,---- 3--------- --*-B-LPI - Pzr Aux Sp.ay ENective
. i . . . . ., , . .
1 . . . . . . . 'j- . . . . q . . O 20 40 60 80 100 120 140 160 180 Time, hours l 21 j i
Framatome Technologies Inc. 86-1266272-00 Figure 8. APS Effective Boron Dilution Time Without Gap Flow (2568 MWt at 1.0 ANS 1971 Decay Heat). f . . s . $ . . 80 -_________,___ _ ___._______ _,_________,_________,_________._________,_________,_________ n . , . . . . . . s . r m . . . . . . . 3 . g 40 _________ _____ ___.__________._________ _________._________._________._________ . .
.o . . . .
g . . . . . . . g, . . . . . . . .
. . . -e-A_LPI- Pzr Aux Spray Effective
~~~-~~
20 -___-_- 7 _______-.-______.q-________;___------T-
+B-LPI - P& W EMm 0 ' '
O 20 40 60 80 100 120 140 160 180 Time, homs 22
Frcmatoma Tcchnologins Inc. 86-1266272-00
- 3. Compilance to 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 before 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 actise dilution method (Ref. 5). 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 lirnit without crediting hot leg nozzle gap or RVW entrainment or lionid 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 failu e renders the active methods inoperable, calculations performed in References 5 and 9 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 solubilit) timit is governed by the core concentration increase and the RCS pressure or temperature. The core concentration increases due to 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. Previous calculations described 5 Reference used 790.5 ft* and 1200 ft' for separate LBLOCA and SBLOCA applications, respectively, without defining clear transition criteria for the evolution from the small to the large volume. Figure 9 provides additional information from which a conservative estimate of the Q1e-dependent mixing volume was based (Ref. 3). Beginning at approximately 2 hours post-LOCA, the mixing volume increases gradually 23
Frematoma Technologics Inc. - 86-1266272-00 4 i until it reaches 1200 ft' at approximately 22 hours. Beyond this time, a constant mixing
. volume of 1200 ft' can be justified and used in boron concentration calculations to establish the minimum time that it takes for the core to reach the solubility limit.
The time-dependent core mixing volume was used in simulations of the spectrum of limiting CLPD LOCAs (from a full double-ended guillotine LBLOCA to 0.05 ft' SBt.OCA) to define the limiting core boron concentration versus time (Ref. 5). 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 from 14.7 to 30 psia to define the minimum time to reach the solubility limit during the time-dependent partion of core mixing volume curve. Figure 10 and Table 4 present 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 10 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) from Table 3 for the A LPI train and Table 2 for the B-LPI train. 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 prior to the APS matchup time, if the A-LPl pump is operating then the matchup time at 54 psia is as early as 43 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 35 hours. )
- -- The compliance calculations show that APS or DL RB-sump flow can be initiated to control the core boron concentration at or before the time that tne 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, the NRC has accepted calculations that 24
y Fram: tome Tcchnologics Inc. :86-1266272-00 show that the hot leg noule gap flows have been shown to be an adequate backup to
= provide effective core boron dilution until the active method can be established.
.i b
1 b i e Y a f 25
Frcmatoms Tcchnologi:;s Inc. 86-1266272-00 Table 4. Minimum Solubility Time vs RCS Saturation Temperature ari Pressure with 1.2 ANS 1971 Decay Heat. RCS Saturation Pressure RCS Saturation Time to Reach the (psia) Temperature (F) Solubility Limit (br) 14.7 212 9 20 228 13 25 240 19 30 250 27 40 267 50 50 281 75 60 293 121 70 303 270 80 312 Never Flgure 9. Core Mixing Volume Versus Time at 2568 MWt and 1.2 ANS 1971. 1400 RCS Pressure 1300 -----------l-----------h-----------{----------- x E '
- 1200 -----------------A.'------x. + >80 psia
- A * + ,
E a . .' A 70-80 psia
- 1100 t------ t-----------
- - - - - - - - ,l - - - - m - - l A o l m 60-70 psia
> 1000 x 50-60 psia tn -----------m----------f----------{-----------
900 - - - - A- - - - 3 '- - - . x 40-50 psia h ' ' g + i e l e 30-40 psia 800 ---------- --------- . ---------------------~
+ <30 psia 700 LBLOCA 100 1000 10000 100000 1000000 Time, s 26
Framatome Technologies Inc. 86-1266272-00 Figure 10. 2568 MWt Matchup Times and Time to Solubility
, Without Gap Flow or Active Boron Dilution,with 1.2 ANS 1971 Decay Heat.
-. . . . . .l . . . . .
. . . . .l . . . . l. . . . -l . . . .
.._q__...l_.....
c0 --------- ---------,------- -------- a--- ---a------- . - -- -.---------s- .------ gp as ct ' * * *
- 2 40 - - - - - - - - , ' - - - - - - - - - ;- - - - --,----------l---------i--------j-------t--------l----------
- s . . . . . . . .
en . . . . . . . v . . . . . . . e . . . . . g *
- l l
-e-A-LPI- Pzr Aux Spray Effective l l
^
B-LPI - Pzr Aux Spray Effective
- 1:- Dump to Sump Actuation Pressure
, l l 20 ----- - - - l- .- - - - - - - -l - --------l--------- '
-e_ Min Uncertainty Adj P for Dump to Sump --
l l l l - + - Max Uncertainty Adj P for Dump to Sump
--*--Composite Minimum Solubility Limit 0 ;. '
O 20 40 60 80 100 120 140 160 180 Time, hours 27
e Frcmntoma Tcchnologins Inc. 86-1266272-00
- 4. 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. These times are very conservative because of the additional decay heat contribution 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. These minimum tirnes would increase even further if lower decay heat levels existed.
4.1 Minimum Times for Active Boron Dilution without Sumo Boron Samoling _ The TSC guidance calculations were performed with the realistic decay heat levels (1.0 times ANS 1971) to determine the rate that the core boron concentration would increase and to define active boron dilutica initiation times for cases when the sump sampling method is not available. These analyses were similar to the compi.ance 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 baron dilution mechanisms such as RVW liquid entrainment or hot leg nozzle gap flow, because they are both transient-specific and time-dependent methods 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 28
< Framatomo Technologics Inc. 86-1266272-00 operator actions to reconfi' : ECCS flow paths, to shut dt,vn an operating L PI pump, or to throttle ECCS flow rates in the event that the core concentration could not be ,
determined. Figure 11 shows the minimum time to reach the solubility limit versus the uncertainty-adjusted saturation temperature. - That same figure shows the APS effective times versus the uncertainty -adjusted saturation temperature. For all three curves, the actual saturation temperature is increased by the maximum uncertainty of +9 F. t 4.2 Sumn Boron Concentration Method for Use in TSC Guidange - The post-LOCA management of core boron concentration has typically been demonstrated with time-based initiation of active boron dilution methods. While this 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. 5). This method allows the TSC operators to infer the core boron concentration using measurements of the sump boron concentration during sump recirculation phase. The underlying premise is that if boron is depleting in t!a 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 cannot refill. Under these conditions, liquid could be retained in the reactor vessel or 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 will have variable boron concentrations are the reactor vessel or reactor building regions. Following a certain CLPD LOCAs, the core boron concentration will increase if there is
- no liquid recirculation flow througa the core. If the core concentration is increasing, then the boron concentration must be depleting in the downcomer and in the reactor 29
,- Fram toma Technologi::s Inc. 86-1266272-00 building. For these calculations, the downcomer concentration was taken as equal to
- that of the sump. This is because of the flushing that occurs as the LPI flow enters the downcomer before mixing and flowing out of the broken cold leg. If the s' imp l
concentration can be measured,- then the core boron concentration can be determined l from bounding calculations that take into consideration limiting boron concentrations
)
and measurement uncertainties. CR-3 has the capability to sample the boron concentration of the recirculating sump liquid using a boronometer and a sample line that attaches to the sump on the opposite i side of the weir wall from the LPI intake pipes. 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 boron 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 e used with the RCS saturation temperature to determine if boron dilution methods are e needed and which methods can be used. 4 The sump difference method calculates an RB mixed-mean boron concentration (ppm liquid), BC%,, by taking the ratio of the total boron mass (Ibm B), B., to the total liquid mass (10'lbm), M., BC% ,,,=B /M.. The total liquid mass is calculated by the sum of the RCS, CFT, BWST liquid mass injected M = Mac3 + Men + M,ws7y , 30
-< Frcmatoma Tcchnologi;s Inc. 86-1266272-00 The total boron mass is determined by the sum of the products of the liquid mass and the boron concentration Bu = Macs
- BCacs + Men
- BCen + M,wsrn*BCows1 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
, cf interest. At a given RCS saturation temperature the boron concentration at the solubility limit is calculated as is the core liquid mass based on the saturatnd liquid density (Ibm /ft') and core mixing volume (ft'). The product of these two is the core 9 boron mass, B , at the solubility limit at the given temperature, B = BC %.
- V. .%
- pg .
The sump boron and liquid mass at these conditions is ct.lculated by B., = Ba - B. M., = M - Vm.w
- pg .
The sump boron concentration when the core is at the solubility limit is BC,, = B , / M., . 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-31
.* Frematoma Technologi::s Inc. 86-1266272-00 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 BWST liquid masses and boron concentrations to define a bounding sump boron difference curve that can be used to establish operator _ action times considering i
instrument uncertainties and reactor building holdup volumes (Ref. 3). Figure 12 demonstrates these results. Concentration differences below and to the right of this j 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. 5). This limit, also shown in Figure 12, will ensure that this dilution method 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 precipitation in the hot leg piping. l l l Figure 12 provides TSC guidance for HLI as a function of temperature. If the sump ! coricentration is unavailable, the TSC needs guidance for establishing _this method based on time. Reference 5 gives this time versus uncertainty adjusted saturation temperature shown in Figure 13. This additional TSC guidance when combined with 1 Figure 11 and Figure 12 provide a composite set of instructions that can be used with 5 or with[ sump boron concentrations to manage the core boron concentration post-LOCA. 6 $M i
-32 1
Framatome Technologies inc. 86-1266272-00 Figure 11. Matchup Times and Temperatures for Active Boron Concentration 140 Control (2568 MWt with 1.0 ANS 1971).
. . . . . . . l 120 -----------:------------!---------- --------j-------- - t------- ---------------;-----------
- APS Eff (B-LPI) 1.0 ANS 711ndicated '
=
- +
100 .-----
--M--APS Eff (A-LPI) 1.0 ANS 71 Indicated l l l l
---------4_----- . -s-----------
y, -m--Uncert Adj Max Precip Limit l l
-.f.-.._----.
l o . I --o-Min Uncert Adj Solubility Limit '
' {'. .
7 80 ------
---------j---------i------- -4r'----------'------------
<c o
/ .
o, o 60 ---------- *---- ------ a, .
-----------2.--------- 2.----------
E . . p . 40 .---------...-----.---- .--.-------. .---------.,---- 20 ----------- - --
! i Vi i
i g . . 200 220 240 260 280 30C 320 340 360 RCS Saturation Temperature,(r) i 33 l l .
4 Framatome Technologies Inc. 86-1266272-00 Figure 12. Core Boron Concentration Control Limits. 350; 3000 ------_ 4---------- 6-_. ------- .-------- --.---------- 2---_-------
-e-Core Solubility Limit a
--H-HLI Mixing Limit l l l l l
-*-DHDL Dump to Sump initiation . .
2500 ------- ' - T----
--------l-----
-+--Uncert Adj Max Precip Limit I' ,'-- l l'7----
[ . . . . . .- . 2000 -----.-----.----------_ -___--__---.__---------,_-. --------_----- - . - _------- ----------- 3. c g
. p. .
n o . . . . . . . e 1500
=-
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g . . . . . . . c . . . . . . G . . . . . .
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- n s . . .' . .' .
500 +---------a----------2---------L-- a.-----------
--i----------
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. . . . . o . .
n .. 200 220 240 260 280 300 320 340 360 RCS Saturation Temperature, F 34
Framatome Technologies Inc. 86-1266272-00 Figure 13. Minimum Boron Solubility and Mixing Limit Time Versus RCS Saturation Temperature.
<<0 - -
, t & . . 9 4 120 -+--Max Solubility Temp (314 F) l__---_----_I-__-__---, l_--_-----
-m--Core Solubility Limit *
--m-HLI Mixing Limit l l l 100 _ ._____ ___.-______ __.;_____ ._...j._________-;_____. . . .,t___.___ ___e_____ .. ._ _;_..._______
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---:---------:----.-----'-_---_----i---____---;_---_---
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40 ___________,________._.4_ -__ __ __ _- _____. ___.__ _______....__ -. ___,__________._,_ . .__.__
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0 ' ' ' 200 220 240 260 280 300 320 340 360 RCS Saturation Temperature, (F) 35
4- - 4 -- A J- m-- %.- 4 .ean-e - E,-s, 6 Frcmntoma Tcchnologi:;s Inc. 86-1266272-00
- 5. Cor.firmation of Boron Dilution via Sump Concentration Measurements Once an active boron dilution method has been initiated, a positive confirmation that it 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 the chosen active boron dilution method. A calculation was done to examine the time that it takes to obtain changes in the boron readings at the boronmeter for the APS and DL RB-sump boron dilution methods (Ref. 5).
The boronometer at CR-3 is located near the ECCS sump suction piping, outside of the sump screen. 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, time is for it to make its way from the break to the boronometm, and the time required to process the sample. The calculations demonstrated that feedback could be obtained between 3 and 9 hours plus the time it takes to process the sample from the boronometer (Ref. 5). 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 1 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 before . nine hours, plus the time it takes to process the sample from the boronometer (Ref. 5).
-These calculations are intended to demonstrate that positive feedback of core boron dilution will no' be instantaneous and that continuous monitoring of the sump boronometer is required both prior to and after the active dilution mechanism is initiated.
l i 36
e Framstom?Tcchnologins'inc. 86-1266272-00
- 6. Summary and Conclusions This report summarizes boron concentration control methods and calculations needed for the CR-3 plant to meet the commitment to the NRC via FPC letter 3F1297-12.
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 su' table for Technical Support Center use was defined, and the time ranges over which changes in the surhp 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 one active dilution method that can be initiated prior to reaching the solubility Smit 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 RWV 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 adcquate 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 4 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 included 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 thermocouples, and time post LOCA. The preferred dilution method is via APS, ) l 37 l i
N' Fram:toma Tcchnologi;s Inc. 86-1266272-00 because this method does not require an LPI pump to be. shutdown. The guidance was comprehensive in that it . provided-information for use 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. k i t '. 4 38
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