ML20212F419

Revised Boron Dilution by RCS Hot Leg Injection

ML20212F419
Person / Time
Site:	Crystal River
Issue date:	10/31/1997
From:	Carlton J, Wissinger G FRAMATOME
To:
Shared Package
ML20212F319	List: 3F1097-32, Application for Amend to License DPR-72,addressing Methodology for post-LOCA Boron Precipitation Prevention. Revised Framatome Technologies,Inc Document 51-5000519-02, Boron Dilution by RCS Hot Leg Injection, Encl ML20212F419
References
51-5000519-02, 51-5000519-2, NUDOCS 9711040280
Download: ML20212F419 (99)

Text

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51 5000519 42 si i I

i BORON DILUTION BY RCS HOT LEG INJECTION l

PREPARED FOR FLORIDA POWER CORPORATION BY FRAMATOME TECHNOLOGIES INC. .

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i OCTOBER 1997 i

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m' 18iE! 28L P PDR

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51 5000519 03  !

}

RECORD OF REVISIONS '!

Rev/Date- DESCRIPTION ' Page No. - i

- Sept.1997 l

' This revision replaces revision -00 entirely, j i

Section 4: Changes were made to the text discussing methods of j detection when boron is concentrating in the core. Boron 22 26 j concentration measurement and incore temperature  ;

measurement uncertainty discussion was added to the text. l Tables 2 and 3 were mod;fied and renumbered as were Figures 4 and 5. ' Bor'on concentration measurement and incore temperature measurement uncertainties were also added to ,

Figures 4A,48,5A, SB, and 50, 52 -l i

Section 5.2: Added discussion ofimpact of Hot leg injection _ on 28  :

the reactor outlet piping,' the reactor vessel and the internals j Section 5.4: The parenthesis after 0.00202 should read  !

(about 0.2 % power) rather than (about 0.12 power).

32 t

.\

' Section 5.4: The word only was added after should, to read.... 33 1

'should only be used in the long term (about 34 days post event)'. Only was added to clarify the Intent of the sentoime.

i Section 6: A paragraph and a new Figure (12 ) have been added 33 1

'o clarify.the dilution flow paths in the reactor vessel before and - 2 aP.?r the hot leg injection flow is large enough to reverse the direction of core flow.

Section 7:The second paragraph was modified to read the same 35

- as the last paragraph on page 20. These paragraphs discuss the sump boron concentration changos if boron is concentrating in the core. This change was made for clarity and continuity. >

Section 9 References 13,14,15 and _16 were added. 37 l

t The page numbers in all Appendices were changed from A1 1,-  !

consecutive text page numbers to A1-1, A2-1, A3-1, etc.

A2-1, t A3-1 '

i 1

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a, i

+ -

3-( ,,

. . . _ , _ ...__-..__ _.___~_,... . _ , . . _ . . _ _ _ - _ _.._ _,-

51c5000519-03 i A1-1 The decay heat relationship should be 1.2 ANS 1971 with  ;

the FTl heavy Isotopes, rather than 102% ANS 1979 with FTl heavy isotopes.

The tabulation of the results of the hot leg injection dilution A1-7 calculailons is identified as Table 4 in the main body of ,

the document rather than in Appendix 1.

Table A 2 is corrected to Table 5 in the main body of the A1-8 document. .

The units of coro power are incorrectly identified as Btu /lb. A1-10 The units are corrected to Blu/sec. .

Table A-3 la corrected to Table 6 in the main body of the A1-12 document.

Table A-4 is corrected to Table 7 in tne main body of the A1-13 document.

Appendix A3 was added to evaluate the Boronometer and incore A31 Temperature Measurement uncertainties.

/Oct 97 Minor editorial changes as reques'.ed by Florida Power Corp.

(David Rice)

/Oct'97 Corrected a calculation error and its results on page 32 and 33 in 4,32 Section 5.4. Changes are on pages 4,32, and 33.

& 33 4

51 5000519-02 TABLE OF CONTENTS l

R E C O R D OF R EVI SIO N S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3 i

1. I N TR O D U C TI O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ;.

2.

SUMMARY

.................................................................................................B

3. ECCS REQUIREMENTS FOR BORON DILUTION, ..............................,10

4. BORON CONCENTRATION CHARACTERISTICS .............................. 17 4.1 L8LOCA......................................................................................,18 4.2 SBLOCA.......................................................................................18

5. B O R ON DIL U TIO N M ETH O D S ... . . .. .... .. .... . . .. .. ... . .. .... . . ........ . ... ... .... . . .... . 26 5.1 O um p-t o-S um p . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.2 H o t L e g inje cti on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , 2 5.3 N o zz l e G a p s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5,4 Auxillary Spray to the Pressurizer...........,.................................... 32

6. REACTOR VESSEL FLOW PATHS FOR HOT LEG INJECTION,,, .....,33

7. CONCLUSIONS....................................................................................,35 8.

M AJ O R A S S U M P Tl O N S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9.

R E F E R E N C E S . . . . . . . . . . . . . . . . . . . . . *. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

APPENDICES

- 1. HOT LEG INJECTION DILUTION CALCULATIONS... ... ... ...... ...... ........A1-1 2.' REACTOR VESSEL HOT LEG INJECTION FLOW EVALUATIONS........A2-1

3. EVALUATION OF BORONOMETER AND INCORE TEMPERATURE .....A3-1' U.EASUREMENT UNCERTAINTIES 5

51-5000519-02 List of Tables 1.- Boron Solubility Limit 2A. Case 1: Spread Shoet for Determining the Sump Concentration Difference Allowed Versus RCS Temperature, Boron Concentrations = 3000 ppm RCS and BWST,3500 ppm CFTs.

28. Case 2: Spread Sheet for Determining the Sump Concentration Difference Allowed Versus RCS Temperature, Boron Concentrations = 2270 ppm RCS, BWST and CFTs 3A. Case 3: Spread Sheet for Determining the Sump Concentration Difference Allowed Versus RCS Temperature, Boron Concentrations = 0 ppm RCS,3000 ppm BWST and 3500 ppm CFTs.

38. Case 4: Spread Sheet for Determining the Sump Concentration Difference Allowed Versus RCS Temperature, Boron Concentrations = 0 ppm RCS,2270 ppm BWST and CFTs 3C. Case 5: Spread Sheet for Determining the Sump Concentration Difference Allowed Versus RCS Temperature, Boron Concentrations = 0 ppm RCS,2270 ppm BWST and CFTs. BWST Volume = 250,000 Gallons

4. LBLOCA Core Boron Concentration for Dilution By Hot leg injaction: 400 GPM Net Hot Leg injection Flow

5. LBLOCA Core Boron Concentration for Dilution By Hot Leg injection: 100 GPM Net Hot Leg injection Flow

6. SBLOCA Core Boron Concentration for Dilution By Hot Leg injection: 400 GPM Not Hot Leg injection Flow

7. SBLOCA Core Boron Concentration for Dilution By Hot Leg injection: 100 GPM Net Hot Leg injection Flow 6

l l

51-5000519-02 l LIST OF FIGURES l 1.- LBLOCA Core Boron Concentration Versus Time 2.

]

Reactor Vessel Arrangement

3. RV Upper Plenum Mixture Levels i

- 4A. Case 1: BWST to Sump Concentration Difference Versus RCS Temperature: Boron Concentrations = 3000 ppm RCS and BWST, 3500 ppm CFTs.

48. Case 2: BWST to Sump Concentration Difference Versus RCS Temperature Boron Concentrations = 2270 ppm RCS, BWST and CFTs SA. Case 3: BWST and " Average' Concentration Difference Versus RCS Temperature: Boron Concentrations = 0 ppm RCS, 3000 ppm BWST and 3500 ppm CFTs.

58. Case 4: BWST and ' Average

• Concentration Difference Versus RCS Temperature: Boron Concentrations = 0 ppm RCS,2270 ppm BWST and CFTs SC: Case 5: BWST and " Average' Concentration Difference Versus RCS Temperature: Boron Concentrations = 0 ppm RCS, 2270 ppm BWST and CFTs.

BWST Volume = 250,000 Ft'.

6. LBLOCA Core Boron Dilution With Dump To Sump

7. Required Dump to-Sump Flow Versus Operator Action Time

8. LBLOCA Core Boron Dilution With Hot Leg Ir:,Mellon

9. SBLOCA Core Boron D;lution With Hot Leg injection

10. SBLOCA Core Boron Dilution With Hot leg injection

11. Hot Leg injection Flow Paths In the Reactor Vessel

12. Hot Leg injection Flow Paths in The Reactor Vessel For Reverse Core Flow 7

q m , ,w - eq m --i-i>, =mm g

51-5000519-02

1. INTRODUCTION This document provides Florida Power Corporation (FPC) Information, evaluations and .

calculations to support emergency core cooling system (ECCS) and reactor coolant system (RCS) hot leg injection flow fo post loss of coolant accident (LOCA) boron control. SMcifically,it: 1) places information supplied to FPC in July 1997 in a formal Framatome Technologies (FTI) format, 2) provides information about boron concentration changes in the reactor building sump and the core with time as a function of core bolling,3) provides information about the change in boron concentrations in the core and sump sfter hot leg injection is initiated, 4) provides an evaluation of the hot leg injection water flow paths in the reactor vessel, and 5) evaluates possible logic for actuation of Crystal River Unit 3's boron precipitation mitigation system (s).

• Several sections of this report document the background information regarding ECCS flow rates required to either control or reduce core boron concentrations, provide boron concentration and solubility data for identification of steps to mitigate boron buildup, evaluate the hoi leg injection natural circulation flow paths in the reactor vessel, and kvaluate the auxiliary spray as a potential boron concentration reduction method.

2.

SUMMARY

Evaluations of core and sump boron concentrations have been performed for both large- and small break LOCAs. Under the most conservative assumptions (ANSI 1971 Decay heat with 1.2 multiplier and the B&W heavy isotopes, no reactor vessel vent '

valve (R\/W) liquid overflow or entralnment, no hot leg nozzle gap flow, and bounding borated water storage tank (BWST), core flood tank (CFT), and reactor coolant system (RCS) boron concentrations), core boron concentrations could approach the solubility limit within about 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> post-LBLOCA. The limiting SBLOCAs remain at elevated RCS temperatures and pressures, and have higher boron solubility limits that provide additional time to detect the core concentration buildup and initiate the active dilution mechanisms. In either case, the core concentration cannot reach the solubility !imit 8

w >m, ,, +,w-,, .-

l 51-5000519-02 l until after the B'WST has emptied.' While on sump recirculation, the core concentration j buildup can be derived from periodic monitoring of the sump boron concentration. The ,

simplest indication is the relationship of the difference between the initial BWST boron concentration and the current sump concentration versus RCS temperature. This  !

method implicitly considers the solubility limit versus temperature and any passive dilution mechanism, such as RVW liquid overflow or entrainment, recirculation of the  !

core liquid directly out of the break, hot leg nozzle gap flow, and boron carryover in steam. If the difference between the initial BWST and sump concentration begins to  ;

grow, then the boron must be concentrating somewhere, most likely in the core. The maximum concentration difference, considering measurement uncertainties, can be used to indicate the conditions under which an active boron dilution mechanism is needed. By monitoring the sump concentrations, the operators will not have to perform unnecessary actions to terminate one train of low pressure injection (LPI) and realign -

the remaining ECCS flow paths.

l If the post-LOCA sump concentration reveals that an active boron dilution process is l needed, then either hot leg injection or dump to-sump can be initiated by the operator  ;

as indicated in proccdures to reduce and control the core boron concentration to well below the solubility limits. LBLOCAs have the smallest allowed sump concentration change that occurs over the shortest post LOCa time interval (4 to 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />), if this time interval is insufficient to monitor the sump concentration, then the operator must initiate the active method based on the time post LOCA. The same is true if the instrument unce;1ainty (sump boron concentration and RCS temperature measurement uncertaintles) does not provide an acceptable operating range and no other vclid l

i Indicator of core boron buildup can be obtained. For SBLOCAs that remain at elevated pressures and temperatures, additional time is available to monitor the sump _

concentration, and the operational concentration margin is larger. The EOPs must be -

structured to include appropriate operator action times to bound any size LOCA with bounding operational limits that consider instrument uncertainty during post-LOCA

. conditions.

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,_ . , - . _.m.- _ . - . . , - ~.-._, , , - . - _ -...,.~~._,.- _ _ _ , _ .._-_, - , . - - - , . , , , , _ .

51 5000519-02 FTl calculations have shown that dump to sump or hot leg injection is successful in rapidly reducing the core boron concentrations. Any dump to sump flow in excess of approximately 10 gpm is adequate for controlling the core concentration once it is initiated, however, the inillation of dump to sump flow must not be performed at RCS cenditions that could compromise the integrity of the sump screens. If the dump-to-sump method cannot be used without possible damage to the sump screens, then hot leg injection by reverse flow through the decay heat drop line at 500 gpm should be used. This method also offers a positive and rapid means for reducing and controlling core boron concentration buildup. In addition to protecting the sump screens, the hot leg injection can be established at h!gher RCS pressures and temperatures, thereby covering the SBLOCAs that hold up in pressures that could not use dump to sump.

Hot leg injection could adversely effect the ability of the hot leg nozzle gaps to provide core boron dilution by reducing the concentrated boron flow through primarily one nozzle and possibly introducing debris entrained in the ECCS fluid at a different location, if the procedures that instruct the operator to initiate the hot leg injection are based on sump concentration change, then the hot leg nozzle gaps are not working effectively, in this case, hot leg injection is needed to provide boron dilution, and any adverse effect on gap flow is inconsequential. Based on these considerations, the activation for hot leg injection should be based only on indicated concentration, and not as a routine action.

3. ECCS REQUIREMENTS Folk BORON DILUTION FTI has ps formed numerous analyses and provided licensing support for CR-3 and the other B&W Owners to demonstrate adequate boron dilution following a postulated cold leg pump discharge (CLPD) loss of coolant accident (LOCA)(References 1 and 2).

During March of this year, a summary was sent to the NRC to report the latest Ret of generic analyses for small and large LOCAs (Reference 11 The largest LOCAs quickly depressurize and reach an equilibrium with the containment pressure veithin 20 to 25 10

51 5000519-02  !

seconds. These postulated break sizes in the Cl PD pipe have the lowest long term saturation temperatures and correspondingly the Icwest boron solubility limit that could i be achieved within 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> post LOCA without credit taken for reactor vessel vent valve (RWV) liquid entralnment or hot leg nozzle gap flow. Credit for RVW liquid entrainment can be taken for the largest LOLN, but as the break size decreases, so does the liquid entralnment, Therefore, the LBLOCA analyses did not credit the RVW I entrainment in bound the spectrum of possibla break sizes. This conservativc ,

approach defined the minimum time for operator initiation of an active buon dilution mechanism at 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> post-LBLOCA. For the larger break sizes, in which the reactor coolant system (RCS) and coatt:nment pressure are in near equilibrium, the dump to-sump method through the decay heat drop line can be used without concern for sump screen Integrity. Therefore, no ECCS flow is required for boron concentration control, This is not the case for the smaller LOCAs with elevated RCS pressures, ,

SBLOCA analyses performed for the boron dilution task identified that smaller break sizes (located on the bottom of the CLPD piping) would result in a long term RCS pressure holdup re!ated to a quasi steady balance achieved between the pumped emergency core cooling system (ECCS) flow and the break flow. The ECCS flow would enter the downcomer and condense the steam patsing through the RWVs. The ECCS inflow rate would exceed the core bolloff rate with ine excess ECCS flowing out of the break once the reactor vesselis refilled to the break elevation. Breaks of sufficient size can discharge all the excess ECCS not needed to match the core bolloff such that the system cannot refill any further. If the downcomer level cannot increase above the bottom of the CLPD nozzlo elevation, RVW liquid overflow cannot occur because of the manometric balances estab!!shed in the reactor vessel. Without RVW liquid overflow, core bolling removes the core decay heat with the RVW cteam flow acting as the necessary energy transport mechanism to the break location. This boiling to remove decay heat concentrates the boron in the core arid upper plenum region.

Calculations show that the hot lag nozzle gaps would be open and passing sufficient liquid fluw to adequately dilute the core boron concentration post-LOCA.

I l

11

_. _ _ _ _ _ _ _. _ _ . . - _ _ _ , , . .a

51 5000510-02  !

i Without credit for the hot leg nozzle gap dilution flow, the core boiling has the potential i

to concentrate all the boron in the BWST, RCE, and CFT in the core region. l

Comparls9n of the borio acid solubility in water with the total mass of boron available to l the systern, shows that the boron would not precipitate at saturation temperatures ,

4 above 305'F (72 psla). Therefore, to preclude the por>sibility of boron precipitation, some active dilution method must be initiated prior to reaching these conditions.

Specifically, an active method may be initiated when the RCS is at approximately 100 psie (328'F) or a higher pressure consistent with the design conditions of the system selected for boron concentration control. A tempercture of 328'F (100 psia )is above 4

the declgn tempersLJre (300'F) for the decay heat removal system (Reference 10), and operadng the decay heat drop line with flow from the hot leg above 300'F will require i turtherMdont ,

Another active dilution method may be available at CR 3 without significant hardware modification. This method uses one operating LPI pump in an alignment in which the LPI provides suction to one high pressure injection (HPI) pump, ECCS injection through the CFT nozzle in the piping run of the operating LPl pump, aM backflow through the LPI cross-connect Il .e backward thrcugh the other idle LPI pump into the RCS hot leg.

This alignment reverses the typical flow direction in the decay heat dropline. Since the  !

LPI fluid that is injected in the hot leg has passed through the decay hoat cooler and is cooled to about 140*F (Reference 10 ), there is no problem related to the design temperature in the decay heat drop line.  ;

To validate this boron dilution method, the hot leg injection alignment needs a definition of acceptable ECCS flow splits both for core cooling and boron dilution. At an RCS a

12 s -,w w .- - , ,-w,~-s- ,,v, .e,----- c--v, .v v e vme - u v gr ~ -- e+--- - ,-, -e m m m 4 .- ==

,v-,

51-5000519-02  !

pressure of 72 psia, the LPI pump should be capable of providing at least 2700 gpm of  !

flow (Reference 10). If a maximum flow of 600 ppm (Reference 11) is assumed for one HPl pump, the remaining 2100 gpm is split between the LPl nozzle and the hot leg l

Injection path with allowances also made for instrument uncertainty and nozzle gap flow

[

'(also refer to Section 9, Assumptions).

The CR 3 total hot leg gap flow at isothermal conditions at 300'F post-SBLOCA is 14.1 l

lbm/s or 103 gpm of ECCS liquid at 140'F. (Reference 1, Table 7A). Only one nozzle  !

gap would pass the hot leg injection flow, so only one-half, or F1.5 gpm of gap flow should be considered. For a LBLOCA, one-half of the non-lsothermal steam  !

cooldown is 22.5 lbm/s or 164 gpm ( Reference 1, figure SA).

The ECCS injection rates needed to match the 1.2 ANS 1971 decay heat bolloff rate and to totally suppress core boiling at 75 psia and 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />,24 hours, and 1 week post LOCA are as determined in the calculations below. (The five (5) hour time is the approximate time that the boron solubility limit is reached for a LBLOCA assuming the core bolling rate corresponds to the conservative decay heat assumptions). The necessary ECCS flow throughputs for more realistic decay heat levels are also calculated.

At 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, the decay heat is:

0.01131 (Reference 8)

• 2568

• 1.02

• 948 = 28,084 Blu/sec At 10G psis with an ECCS ;olut ie nperature of 140*F, the ECCS flow needed to match core bolloff is:

W = (28,084)/(1187 - 108) = 26.0 lbm/sec = 190 gal / min Bulk core bolling could be suppressed with an LPI flow of; 13

. -- - - - . .. . ~ . , - -

51 5000519-02 W = (28,084)/(298 - 108) = 147.8 lbm/sec = 1081 gal / min At 75 psia with an ECCS Inlet temperature of 140'F, thu ECCS flow needed to match core bolloffis W = (28,084)/(1182 - 108) = 26.1 lbm/sec = 191 gal / min Bulk core bolling could be suppressed with an LPl flow of:

W = (28,084)/(278 - 108) = 165.2 lbm/sec = 1208 gal / min At 14,7 psla with an ECCS inlet temperature of 140*F, the ECCS flow needed to match core bolloff is:

W = (28,084)/(1151 - 108) = 26.9 lbm/sec = 197 gal / min Bulk core boiling could be suppressed with an LPI flow of :

W = (28,084)/(181 - 108) = 384.7 lbm/sec = 2812 gal / min At 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the decay heat is:

0.00703 (Reference 8)

• 2568

• 1.02

• 948 = 17,< Blu/see At 75 psia with an ECCS inlet temperature of 140' F, the ECCS fbw needed to match core bolloff is:

W = (17,457)/(1182 - 108) = 16.3 lbm/sec = 119 gal / min Bulk core boiling could be suppressed with an LPI flow of:

W = (17,457)/(278 - 108) = 102,7 lbm/sec = 751 gal / min 14

51-5000519-02 At 14.7 psia with an ECCS inlet temperature of 140' F, the ECCS flow needed to match core bolloffis:

W = (17,457)/(1151 - 108) = 16.7 lbm/sec = 122 gal / min Bulk core bolling could be suppressed with an LPI flow of:

I W = (17,457)/(181 - 108) = 239.1 lbm/sec = 1748 gal / min  !

\

. At 1 week, the decay heat is:

0.00384 (Reference 8)

• 2568

• 1.02

• 948 = 9535 Dtu/sec ,

At 75 psia with an ECCS Infot temperature of 140*F, the ECCS flow needed to match core bolloff Is:

W = (9535)/(1182 - 108) = 8.88 lbm/sec = 65 gal / min Bulk core boiling could be suppressed with an LPI flow of:

W = (9535)/(278 - 108) = 56.1 lbm/sec = 410 gal / min At 14.7 psia with an ECCS inlet temperature of 140' F, the ECCS flow needed to match core bolloffis W = (9535)/(1151 - 108) = 9.14 lb.m/sec = 67 gal / min Bulk core bolling could be suppressed with an LPI flow of :

W = (9535)/(181 - 108) = 130.6 lbm/sec = 955 gal / min The ECCS injection rates needed to match the 1.2 ANS 1971 decay heat bolloff rate at 75 psia and 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />,24 hours, and 1 week _ post-LOCA were calculated to be: 191 gpm, 119 gpm, and 65 gpm, respectively. Th5 calculations also show that core boiling could -

15 d

.)

_ . . - - ,.x...-

51 5000519 02 be totally suppressed with core ECCS throughputs of 1208 gpm,751 gpm, and 410 gpm at 75 psia and 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />,24 hours, and 1 week, respectively, Using mcre realist!c decay heat levels (0.75 times the 1.2 ANS 1971 fission product decay plus B&W heavy isotopes), the core boiling could be suppressed with ECCS throughputs of 75% or 906, 563, and 308 gpm flow rates, respectively. Suppression of core boiling eliminates the mechenism that concentrates the boron, thereby addressing the boron concentration control for the duration of the transient.

Based on these required flows, the hot leg injection flow must be 191 gpm plus 52 gpm or approximately 250 gpm at 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> post LOCA at 72 psia RCS pressure to match decay heat and gap flow through one nozzle. Additionalliow, however, is needed to initiate a reverse core flow sufficiently large to totally suppress core boiling and to provide boron dilution. As noted above, a flow rate of 2812 gpm (at 14.7 psia and 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> post tip) is required to completely suppress core bolling. (Excess flow above 2812 gpm at 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> is required to assure that flow is sufficient to cover potential nozzle gap by-pass). FTl believes that a hot leg flow with a 250 gpm excess above the decay heat and gap flow is adequate for core boron dilution with or without an operator-assisted RCS cooldown. That is, a total hot leg injection flow of 500 gpm is adequate to provido boron dilution from 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> post-SBLOCA and beyond. If this were a LBLOCA,197 gpm (see above)is needed for core bolloff makeup at 14.7 psia and a maximum single gap flow of 27.25 lbm/s or 199 gpm (estimated CR-3 gap at 14.7 psia with Tnvi = 212*F and Tav = 400*F at 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> post-LOCA RV cooldown iri steam)

(Reference 2)is needed.

In this LBLOCA case, the recommended 500 gpm hot leg injection flow still exceeds the 197 gpm plus 199 gpm or approximately 400 gpm needed for boiioff makeup and gap flow considerations. This example o'nly has 100 gpm excess flow for boron dilution.

The excess will increase with time as the decay heat boiloff and gap size and flow decrease. At 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the boiloff is 122 gpm (see above) and the gap flow is extrapolated from the nozzle gap data of Reference 1 to be less than 100 gpm. The excess hot leg flow at this time will be greater than 250 gpm. For LBLOCA the excess 16

I 51-5000519-02  !

ECCS can be smallar, since the boron concentration does not have to be reduced to compensate for possible solubility decreas'es due to subsequent RCS_depressurization after 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Therefore, the recommended 500 gpm is adequate for LBLOCA I f

concentratico control as well, i

With a minimum of 500 gpm of hot leg injection How and 600 gpm for HPl flow, approximately 1600 gpm of the 2700 gpm LPI pump flow is left for LPI nozzle flow and '

instrument uncertainty. Historically,1000 gpm per LPI nozzle has been assumed to be the target value for securing the HPl pumps. When using the hot leg injection ,

alignment, it is reasonable to target 1000 ppm for the one flowing LPI line, which leaves 600 gpm of real pump flow for instrument uncertainty or flow imbalance at 75 psia.

Below 75 psia, the pump flow will increase and additional flow may be available to the t

hot leg injection path, such that, once initiated, the flow may be adequate to suppress core boiling with best-estimate or realistic decay heat levels.

in summary, FTl recommends that the hot leg injection alignment provide flow for one HPl pump, a minimum reverse flow of at least 500 gpm through the decay heat drop line for boron dilution, and approximately 1000 gpm into one CFT nozzle. If possible, the hot leg injaction flow should be increased from a minimum of 500 gpm to roughly 900 gpm. This flow rate is capable of both suppressing core bolling and removing the core boron concentration mechanism when realistic decay heat contributions are considereJ.

4. BORON CONCENTRATION CHARACTERISTICS Boron concentraFon effects have been reported by FT! for the B&WOG Boron Dilution project in Reference 1. Calculation of the boron concentration and dilution were-performed for the B&WOG plants, including CR-3. The cases of interest for CR-3 include the LBLOCA ( break size > than 0.5 Ft') and the Cold Leg Pump Discharge (CLPD) SBLOCA of 0.05 Ft' area, The following sections describe the boron concentrating and dilution processes for the large and small break LOCAs and discuss 17 l

s . . _ . -. 2. _ . . _ . . . ._ _ _ -,, _ _ _ . , _ . _ _ , _ _ , _ , _ _ -

51-5000519-02 the several methods for dilution of core boron concentrations.

4.1 LBLOCA The characteristic blowdown for the LBLOCA is rapid, and equilibrium between the RCS and the reactor building pressures can be expected to occur within about 30 seconds. The LBLOCA is of interest to deboration methods, because the LBLOCA thermal conditions offer early and vigorous core boiling such that the boron solubility limit is rapidly approached. Avoidance of boron precipitation in the core requires prompt recognition of the conditions and timely corrective measures.

The saturation temperature and pressure for the LBLOCA will rapidly approach atmospheric conciitions (212 'F /14.7 psla). The solubility of boron in reactor water is a function of the water temperature, and at 212'F (saturated) the limiting solubility is about 50,300 ppm boron. Table 1 gives boron solubility versus temperature (Reference 1). The core and sump boron concentrations with time for the LBLOCA, assuming no dump-to sump, hot leg injection or opening of nozzle gaps, is shown on Figure 1. The core boron concentration reaches the solubility limit at just over 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> post LOCA.

If boron is concentrating in the core region, the sump boron concentration fcc the LBLOCA will change about 600 ppm over the first five (5) hours post -LOCA.

Boronometer measurements along with reactor and reactor building pressure, incore temperature measurements and RCS temperature measurements, can form the basis for actuation of dump-to sump, hot leg injection or auxiliary spray methods of core boron dilution.

4.2 SBLOCA A SBLOCA transient results in a rapid subcooled primary system depressurization until the hottest regions in the RCS saturate. Hot leg flashing causes steam to accumdate 18

l 51-5000519-02 i

in the top of the hot leg U-bends, which interrupts the loop natural circulation flows. The loss of RCS flow reduces the core inlet subcooling and intensifies the core boiling due to the decay heat generation in the fuel pins. The steam produced from flashing and boiling 6 , cumulates in the upper portions of the reactor vessel, as shown in Figures 2 and 3. The reactor vessel inventory quickly approaches a quasi steady condition shown in Figure 3 in which the mixture level inside the plenum cylinder is slightly above the bottom of the largs holes in the upper plenum cylinder. The steam and liquid that flows through these ho:es separates in the outlet annulus region. The liquid flows  !

downward and returns to the inside of the plenum cylinder through the small holes found opposite the two hot leg nozzles. The separated steam flows up and out of the RWVs to be condensed on the ECCS flows or lost out of the break. The downcomer level remains near the bottom of the cold leg inlet nozzle. The outlet annulus level remains below the RVW spillover elevation such that no liquid flows through the RVWs. Withoilliquid circulation through the core region, the core boiling continues to concentrate the boric acid contained in the initial RCS fluid or injected by ECCS flows.

There is some !iMed boron solubility in the steam (i.e., boron carryout with the RVW steam flow) but m rate of outflow is much less than the boiling production rate, thus causing the concentration to increase.

The break size and location dictates the rate of RCS pressure decline end ultimately the maximum core boron concentration increase. A larger SBLOCA located on the bottom of the CLPD pipe at the elevation of the reactor vesselinlet nozzles will rapidly depressurize the RCS activating CFT and LPI flows. The break size is sufficient to discharge all the excess ECCS flow not needed to replace the liquid boiled by decay heat or lost by flashing during RCS depressurization and cooling to ambient conditions (14.7 psla). This loss of ECCS out of the breah 'imits the downcomer level to slightly above the bottom of the cold leg pipe. 'This de mcomer level produces an elevation head that supports a core and upper plenum mixture level (liquid and bubbles) that reaches the elevation of the large flow holes in the plenum cylinder. If the downcomer level could be increased significantly above the bottom of the cold leg pipe, there is a much better likelihood that some RWV liquid spillover would be predicted. This wou!d 19 l

51-5000519-02 be the case for e. cold leg pump suction (CLPS) or a cold leg pump discharge (CLPD) break at an elevation above the cold leg nozzle center,line or the core flood tank (CFT) line break. The excess ECCS would re r'! the downcomer to a higher level which would allnw RVW spillover and liquid recircts. a. out of the core region. The recirculation would begin to dilute the growth of the boron concentrations which had built up earlier in the transient. Similarly, a break in the hot leg pipe would allow the system to refill  !

until liquid is discharged out the break. This break location would also allow core liqJid circulation to restrict the traximum core concentration increase.

From the previous discussions, it is co,ncluded that a break on the bottom of the CLPD pipe will restrict the downcomer level to a maximum value such that the manometric balances in the B&W-designed reactor vessel and RCS will not support re-establishment of RVW overflow. This inventory distribution will tend to remain relatively constant for a very long time without operator intervention. The system will gradually depresstrize as core decay heat drops. As long as the break can ,

compensate for the core decay heat decrease by discharging the excess ECCS not boiled in the core and the core steam that is not condent.ed on the sub cooled ECCS injection the systom will remain in this state. This configuration can lead to extended periods of core boiling in which the core boron concentration will increase until a dilution mechanism is implerc. anted.

For SBLOCAs that remain at RCS temperature above 305'F (72 psia), the solubility of boron in RCS water is such that all the boron in the system can be in the core water solution (up to 156751 ppm) and not precipitate. An indicator : hat the nozzle gaps or other core boron dilution means are not effective would be an indication of sump concentration of about zero ppm, or a BWST initial concentration to sump concentra' tion difference of about 3000 ppm.

ACS cooling and pressure decline for small break LOCAs are determined by the size

-and location of the break. They also determine the path the must be established to vent l V 20

.- -- - ., , 3

51-5000519-02 l

the core steam from the system. The smaller small breaks are expected to refill and natural circulation will prevent core boiling so that boron concentratior, is not a concern. /

Larger small breaks (<0.5 ft') can remain in a core boiling mode for significan' periods, Those creaks that tend to remain at pres'sures greater than the cut in pressure fer the LPI system are not likely to cool until the operator iakes action (possib!/ with non-safety equipment) to depressurize and cool the RCS. It is these breaks that may require a means to control core boron concentration prior to cooldown.

As the system depressurizes and the c0re decay heat declines, the ECCS inflow will increase md provide a mechanism for system refill. The refill will not occur if the break is large enough because it will compensate by discharging any core steam not condensed by the ECCS injection plus the excess ECCS and condensate not needed to makeup for the core boil off rate, if this is the case, then the system will remain in this stable vesselinventory configuration for extended periods of time. The core heat is adequately removed by saturated pool boiling which continues to concentrate boron in the core until a liquid flow dilution mechanism is achieved.

System refill may be accomplished for tiny breaks where the HPl system flow can exceed the break discharge at higher RCS pressures, or once LPI flow is established at lower pressures. RVW liquid overflow may be established by system refill (The refill could be augmented by certain operator actions to depressurize the RCS. These actions to depressurize and cool the RCS may use non-safety grade equipment.) If RWV liquid overflow cannot be established, the hot leg nozzle gaps can provide a reliabin, passive core boron dilution flow that is very effective at low RCS pressures and temperatures.

The 0,05 ft' case represents the break size that does not depressurize rapidly and tends to " hang up" at or near the LPI injection pressure. The RCS leak flow rate from this break is maintained by one LPI pump for a relatively long period of time. Core bolling and boron concentration persist for this SBLOCA for a significant period: the RCS pressure is about 15G psia at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

21

l 51-5000519-02 The following discussion presents a method (the 'Delt a Method") that can be used to detect boron buildup in the core. Five LOCA cases are presented with different initial BWST, CFT and RCS boron concentrations and BWST volumes to support this of' ort.

The " Delta Method" is based on the assumption that, post-LOCA, boron is either in the sump or concentrating in the core. If boron is concentrating in the core, the sump concentration will be decreasing. If boron is not concentrating in the core, the sump boron concentration will be relatively constant. The core boron solubility limit can be determined for a range of core temperatures and related to the difference between sump concentration and an initial boron concentration value such as the initial BWST concentration or a mixed mean average initial post-LOCA sump concentration.

The cases identified below are developed to show the ' Delta Method" of boron concentration identification and the boron solubility limit as a function of temperature.

The cases are:

Volume Case 1 Case 2 Case 3 Case 4 Case 5 BWST 3000 ppm 2270 ppm 3000 ppm 2270 ppm 2270 ppm CFT 3500 ppm 2270 ppm 3500 ppm 2270 ppm 2270 ppm s RCS 3000 ppm 2270 ppm 0000 ppm 0000 ppm 0000 ppm, The BWST water volume is assumed to be 350,000 gallons for :ases 1-4. Case 5 assumes the BWST volume is 250,000 gallons. In all cases, a core volume of 790 Ft*

is used.

Tables 2A,28,3A,3B and 3C present the calculations from which the ' Delta Method' is developed. Cases 1 represents the upper bounds for boron concentration in the BWST, CFTs and the RCS at the beginning of a core cycle. Case 2 is a nominal boron concentration case with the BWST and the CFT at the improved Technical Specification (ITS) lowerlimits. Cases 3,4, and 5 are presented for RCS boron concentration near zero for the end of a core cycle. The tables present the ' Delta" function for BWST to sump and " average boron concentration" to sump concentration 22

51-5000519-02 1

differences. [The ' mixed mean average boron concentration ' is the calculated arithmetic average of the water and boron content in pp boron of the BWST, CFTe, and the RCS at the time the LOCA is assumed to occur). It is assurr 7d that the boron not in the sump is concentrating in the core. Figures 4A,4B, SA,58, and 5C are plots of the results. Each figure presqnts several curves as follows:

The " Delta function" as noted above is a boron concentration difference between the BWST or a mixed mean average boron concentration and the sump concentration.

In cases 1 and 2 the RCS boron concentration is assumed to be 3000 ppm and 2270 ppm boron res,oectively. For these cases (1 and 2) the BWST boron concentration and the mixed mean average concentrations are approximately equal so that the " mixed mean sump" and BWST- sump concentration differences are approximately equal. For cases 3,4 and 5 the RCS initial boron concentration is assumed to be zero. For these cases, the BW3T to sump and the Tilxed mean average boron concentration to sump boron concentration will be different because the assumption of zero boron concentration in the RCS , Zero ppm in the RCS gives a mixed mean avers; iinitial st'mp concentration less than the initial BWST boron concentration. Figures SA through SC show both the mixed mean average boron concentration to su,np boron concentration difference as solid square points and the BWST to sump difference as solid diamond points. The mixed mean average to sump concentration difference is the more appropriate boron concentration measurement for end-of-core cycle (EOC) conditions.

The figures also show the results of different treatnients of measurement uncertainties for the boronometer and the incore temperature measurements. The different measurement uncertainty treatments include:

- Subtraction of the boron measurement uncertainty from the " delta function" plus an incere temperature measurement uncertainty shift of 43.5'F

- Square root of the sum of the squares (SRSS) approach.

- A " Monte Carlo" approach for case 1 only.

23

l 51-5000519-02 The uncertainty in the boron measurement is taken directly from Attachment 1 of reference 13 which is a plot of the boronom^ter measurement uncertainty (+/- ppm) as a function of the actual boroa concentration in ppm. (This relationship is shown as i Figure A3-1 in Appendix 3). Over the boron concentration range of interest (up to about 3000 ppm), the boronometer uncertainty ranges from about +/- 65 ppm at 1000 ppm to about +/-185 ppm at 3000 ppm boron concentration. From reference 14, the incore temperature measurement uncertainty in the temperature range of interest of 212 'F to 305 'F, is + 33.25 'F, -43.5 'F. The boron and temperature measurement uncertainties shift the " Delta Function" ctirves down and to the right, resulting in less marg'n for acceptable operation. These measurement uncertainty approaches are discussed below.

Figures 4A through SC show treatment of the measurement uncertainties by simply subtracting the boronometer measurement uncertainty (a function of the boron concentration being measured as defined by reference 13) from the delta function and adding the incore temperature measurement uncertainty of +43.5 'F to the " Delta Function'. This incore temperature measurement uncertainty plus the boron measurement uncertainty are subtracted from the mixed mean average boron concentration minus the sump concentration to give the " Temperature & Boron Uncertainty Average -Sump" " Delta" function. This title is abbreviated to " Temp &

Boron Uncert Ave - Sump" and shown as a plot with open triangles on Figures 4A-5C.

The " Temp & Boron Uncertainty Ave- Sump' ' Delta function' indica'.ed by the open triangle plots on each Figure represents a very conservative treatment of the measurement uncertainties. (The data for this simple treatment of the measurement uncertainties is also tabulated on Tables 2A through 3C for the five cases).

A" square root of the sum of the squares"(SRSS) treatment of the measurement uncertainties is described in Appendix 3. The results of the SRSS approach are also plotted on Figures 4A through SC and are labeled SRSS Adj Ave-Sump. The SRSS plots are noted by -x- and a dashed line. The total measurement uncertainties 24

51-5000519-02 represented by the SRSS method is a reasonable approach to the measurernent uncertaintiec because the measurements (boronometer and incore temperatures) are independent of each other, FTl also performed a " Monte Carlo" measurement uncertainty evaluation for case 1.

The results of the Monte Carlo uncertainty evaluation closely match the square root of the sum cf the squares method discussed above. The Monte Carlo measurement uncertainty method and calculation is described in Reference 16. The results of the case i measurement uncertainty are shown as the curve defined by the solid diamond points on Figure 4A.

The measurement uncertainty results indicate that the lowest " Delta" boron concentration is indicated for the cases where the boron concentration is highest in the BWST, CFTs, and the RCS, (Case 1 above). The lowest SRSS indicated boron difference occurs at 212 'F (The lowest temperature expected for a LOC') for case 1 and is about 310 ppm. A ' Delta fanction indication of 310 ppm appears to give l

adequate margin to provide information to decide on actuation of an active dilution method. For smaller breaks, the RCS temperature is higher, and the boron measurement uncertainty is slightly smaller, but the increased boron solubility at the higher temperature provides a significantly larger " Del'a Method' margin on which actuation of active boron dilution procedures can be based.

. As can be seen from the Tables and Figures, the " Delta Method" indicates that boron is or is not concentrating in the core and provides information to actuate active boron dilution processes. The indicated " Delta Function" margin improves with decreasing initial boron concentration of the BWST, CFTs and RCS. For case 5, (smati BWST volume of 250000 gal, zero ppm boron in the RCS and 2270 ppm in the BWST and CFTs) the measurement uncertainty corrected " Delta Method' indicates an average initial boron concentration to sump difference of about 490 ppm at 212 'F, and about 900 ppm at 260 *F.

25 4

51-5000519-02 This information suggests that the ' Delta Method

• can be used to evaluate the need to actuate active boron dilution methods for LOCAs and that a more appropriate method for end-of-core cycle conditions is to use the " average boron concentration" (the mixed mean average) to sump concentration difference to account for conditions when the initial RCS boron concentration is low or zero.

5. BORON DILUTION METHODS 5.1 Dump-To-Sump The dump-to-sump method of dilution of core boron is an effective solution, provided the CR-3 sump screen issue can be resolved and/or for LBLOCAs that the LBLOCA reactor building pressure and the RCS pressure can be identified as equal or near equal so that blowdown through the dump to sump line will not damage the sump screen. A dump-to-sump deboration for the CLPD LBLOCA is shown on Figure 6. In this case, a 7.8 gpm dump to sump was initiated at 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The core boron concentration just reached the solubility limit from about 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> until 17 hours1.967593e-4 days <br />0.00472 hours <br />2.810847e-5 weeks <br />6.4685e-6 months <br /> and began a steady decrease thereafter. Earlier actuation of the dump to sump would have allowed the core boron concentration to decrease earlier. The amount of dump-to-sump flow required for various times of actuation this dilution method is shown in Figure 7 (from Reference 1). For example, a dump-sump-flow rate of 10 gpm allows a delay of about 5.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> post event to actuate the system.

5.2 Hot leg injection RCS

• Hot leg injection" provides an effective means of diluting core boron concentrations by aligning one decay heat (or LPI) pump to pump to the reactor vessel CFT nozzle as well as to pump flow backward through the other LPI pump (decay heat 26

)

51-5000519-02 pump), through the decay heat system piping cross connects and into the decay heat drop line attached to the hot leg pipe. . An evaluation using methods similar to the spreadsheet methods used in Reference 1 (see Appendix A) has been used to estimate the change in core and sump boron concentrations after the hot leg injection is initiated. The major assumptions associated with hot leg injection are:

. The Decay Heat Removal /LPI system equipment is accessible for alignment so that water can be injected in reverse flow th ough the decay heat dropline to the nozzie on the IRCS hot leg piping.

. The Hot leg injection flow is 500 GPM at 140 'F.

. The LPI injection flow to the reactor vessel (CFT) is 1000 gpm at 140*F.

Hot leg injection d;lution of high concentration core boron has been evaluated for two cases as follows :

Case 1: The first case is the CLPD LBLOCA. The core boron buildep fu this case is also shown in Figure 1. The saturation temperature for this case is assumed to be 212 F and the solubility limit at 212'F is about 50,300 ppm (Reference 1). The core boron concentration approaches the saturation limit at just over 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. Core boron dilution by hot leg injection is assumed to begin at 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and the boron concentration reductions in the core and the boron buildup in the sump are shown on Figure 8 and Tables 4 and 5. It is assumed that some of the hot leg injection flow leaks through the nozzle gaps and is not available for' core boron dilution. The core boron dilution rates given on Table 4 assteme that 100 gpm injection flow is by-passed through the nozzle gaps, leaving 400 gpm for core boron dilution. A net hot leg injection flow rate of 100 gpm (400 gpm by pass through the RV nozzle gaps) is also analyzed for this LBLOCA and reported in Table 5. The results of these cases indicate that the core boron concentration is rapidly reduced and approaches the sump boron concentration levels within about one-half hour after 400 net gpm hot leg injection was initiated. The lower not hot leg injection flow rate of 100 gpm also reduces the core boron concentration, 27 F

( .

51-5000519-02 but at a slower rate.

Case 2: The second case of hot leg injection core boron dilution was evaluated for the 2

limiting 0.05 Ft CLPD SBLOCA. This SBLOCA case tends to remain at or above 72 psla/304*F for a significant period. The boron saturation limit is approached at just over 159 hours0.00184 days <br />0.0442 hours <br />2.628968e-4 weeks <br />6.04995e-5 months <br /> (Reference 1). Hot leg injection was assumed to be initiated at 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> post trip for this case when the core boron concentration was about 122,000 ppm. The core boron concentration reduction case was also analyzed with net hot leg injection flow rates of 400 gpm (100 gpm by-pass) and 100 gpm,400 gpm by pass.

The reduction in core boron concentration again was relatively rapid for the rapid 400 gpm net hot leg injection flow rate and slower for the net hot leg injection flow rate of 100 gpm (Figure 9). The boron concentration approached the initial concentration within about an hour after net hot leg injection flow of 400 gpm was initiated. The core boron concentration dilution rate with 100 gpm net hot leg injection was slower but steady requiring about 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to reduce the core boron concentration from 122,000 ppm to about 9000 ppm. These eval:13tions indicate that hot leg injection is a 'talid and efficient deboration methods.

Although the hot leg injection evaluations have been performed on the basis of a hot /

leg injection flow rate of 500 gpm to the decay heat drop line, hot leg injection flow rates of the order of 700 to 800 gpm can be expected if hot leg injection through the decay heat dropline is required to dilute core boron concentration, in addition to the boron dilution evaluations discussed above, FTl has also evaluated the impact of the hot leg injection on.the hot leg (reactor outlet) piping, the reactor vessel, and the reactor vesselinternals. The evaluation inctudes:

-Steam water interaction and or cold water-hot water interactions (water hammer).

-Stratified liquid flow in the hot leg pipe

-Temperature rates of change for the reactor vessel and the reactor vessel internals.

-Operation within the Pressure -Temperature ( PT) limits.

28 1

51-5000519-02 Discussion of the evaluation follows:

" Water Hammer" The injection of sump water , assumed cooled to 140 'F by the operating decay heat coolet, into the reactor vessel hot leg is not expected to result in steam -water interactions (' water hammer") because the introduction of hot leg injection fluid into the hot leg is injected to a water-to water interface. The hot leg pipe will have a water level consistent with but deeper than the water level in the cold leg pipe for the assumed cold leg pump discharge (CLPD LOCA) break . The hot leg injection flow velocity is relatively low (less than about 0.25 ft/sec) in the hot leg pipe and is expected to run along the bottom of the hot leg pipe under the saturated fluid in the pipe, gradually mixing with the hotter water in the hot leg pipe until the injection fluid reaches the upper plenum cyiinder (Figure 11). This fluid injection into the hot leg is similar to the injection sites of the HPl into the RCS cold legs, and to the core flood line (CFL) nozzles on the reactor vessel. Direct contact of colder hot leg injection water with steam and the resultant " steam water interaction (" water hammer") is not expected to occur.

" Thermal Stratification" The hot leg injection flow velocity is relative low (less than about 0.25 ft/sec) in the hot leg pipe and is expected to run along the bottom of the hot leg pipe under the saturated fluid in the pipe, gradually mixing with the hotter water in the hot leg pipe until the injection fluid reaches the upper plenum cylinder (Fioure 11). At the reactor vessel, the injection fluid flows through the holes in the inner plenum (Figure 11) cylinder and is expected to begin vigorous mixing with the steam - water mixture in the plenum. The injection fluid is ruw expected to be at saturation temperature for the pressure in the reactor vessel (212 to 305 F).

Since the hot leg injection fluid !s expected to flow under the saturated fluid in the hot leg pipe and reactor outlet nozzle, thermal stratification of the hot leg injection fluid 29

51-5000519-02 between the decay heat drop line nozzle and the reactor internals can occur. However, there is no significant pressure on the system (about 72 psia maximum) and the delta between the hot leg injection fluid is relatively small (140 F to 212 F = 72 F or (140 F o 305 F= 165 F). Any stresses generated by this thermal stratification are expected to be insignificant for this LOCA event.

" Rates Of Temperature Change' As the decay heat rato decreases with time, hot leg injection fluid is expected to eventually remove the core decay heat by reverse flow through the core with sensible heat removal (delta T cooling). The suppression of core boiling is expected to be accompanied by a temperature reversal wnerein the colder (140 F) hot leg injection water enters at the top of the co.re flows downward through the core removing heat by subcooled heat transfer and exiting the core at a higher temperature but below the boiling point. Since the decay heat will be slowly decreasing the change in the decay heat removal process is expected to take place over a long period of time (days) so that the changes in temoerature in the reactor vesse! end the internals are slow and insignificant relative to the temperature changes in the reactor vessel and internals immediately post - LBLOCA.

" Pressure-Temperature Limits' in the temperature pressure range where hot leg injection is expected to operate, (saturated water in the range from 212 F to 305 F) , the temperature and pressure conditions are well below the temperature - pressure limits (Reference 15) for Crystal River Unit 3. No additional significant pressure or thermal stresses are expected for these operating conditions,

" Reverse Flow in The Core" The eventual reversal of flow direction in the core will have lo impact on tho fuel assemblies or their support structures. The downward flow velocity for flow rates in the range of 500 to 800 gpm is less than shout 0.05 ft/sec. This velocity is so much less 30

51-5000519-02

- than the normal core velocity (about 15 ft/sec) that hydraulic forces and flow loads on the fuel assemblies are basical!y gravitational forces. No impact is expected on the fuel assemblies because of reverse flow from hot leg injection.

P in summary, the results of this hot leg injection evaluation indicate there are no thermal-hydraulic, mechaolcal, or core conditions that will prevent use of hot leg injection to dilute core boron concentration. These evaluations indicate that hot leg injection is a valid and efficient deboration method.

5.3 Nozzle Gaps Hot leg to plenum cylinder nozzle gaps provide a passive means for dilution of core boron. Figure 10 shows the reduction in core boron concentration after the nozzle gaps are assumed to open.

The nominal nozzle gaps in CR-3's reactor vessel range from 0 inches up to 0.90 inches (Reference 1). The CR-3 sump has % inch mesh wire screen to prevent large debris from entering the sump (Reference 9). The largest pieces of debris that could reach the sump is % inch square. The center line of the horizontally mounted -suction nozzles for the LPl/DHR pumps are located 1 Ft-9 inches (21 inches) above the bottom of the sump liner (Reference 9). The LPl pump suction nozzles in the sump are 16 inches in diametei (lD) (Reference 9). This gives a clearance of 13 inches (21 inches -

8 inches) between the bottom of the sump and the bottom of the LPI suction nozzle. It is unlikely that any particles % inch gquare or less in size, and heavier than water will reach the suction of the LPI pumps. Any material % inch square of less that reaches the suction of the LPI pumps floats or is of neutral buoyancy. Assuming floating particles of this size reach the RCS hot leg through the decay heat drop line, such particles will float or be slowly swept by the hot leg injection stream to the reactor vessel and into the upper plenum, Particles of this size can be drawn into the nozzle

. gaps and potentially clog them.

31 r,-

1 51-5000519-03 Calculations (Reference 1) have shown that the hot leg nozzle gaps will be open and provide sufficient dilution flow in the absence of debris collaction in the gap itself.

Various studies were used to evaluate the variatione on gop size and flow and its effect on the boron dilution mechanism. It was confirmed that a reduction of the smallest as-built gap area by ninety percent (90%) during the long term cooling phase

-does not preclude gap flow from providing adequate core boron dilution. The gap flow mechanism was also shown to provide adequate flow for a small range of non-Isothermal temperatures. The shell temperature can be up to 23*F cooler than the RV

. internals without totally closing the gap and inhibiting the dilution flow.

5.4 Auxiliary Spray to the Pressurizer Auxiliary Spray (by the decay heat or LPI pumps)is a possiblo means to achieve hot leg injection (about 40 gpm) for boron dilution in the longer term (about 34 days post-event). A minimum _ time for operator action to initiate an active boron dilution flow peth is identified in Reference 1. The decay heat drop line method (dump-to-sump) for most of the B&W-designed plants is not single failure proof until after the decay heat arops below the value where 40 gpm (assumed flow rate) of pressurizer auxiliary soray can offset the core decay heat and initiate a reverse flow through the core. This limited auxiliary spray flow rate will be successful at matching the core decay heat at very long times after reactor shutdown. If the core power exceeds the auxiliary spray absorption, It will be totally boiled away, leaving the boron that was injected with this flow, thereby f

contributing to the core concentration increase at a rate similar to that obtained via the core inlet ECCS flow.

t The maximum core power fraction that 40 gpm (5.472 Lbm/sec) at 140 *F can absorb for an initial power level of 2568 MWt at an inlet enthalpy of 108 Btullbm and saturated steam enthalpy of 1150.5 Btu /lbm at 14.7 psia ( Reference 7) is:

l

- P/P.o 2sa um = 5.472 lbm/sec *(1150.5-108.0) Btu /lbm / [(1.02)*(2568 MWt)*

(948 Blu/s/MWt)) = 5704.56.Blu/sec / 2,4d3,299 Btu /sec = .00229, 32 u,

51-5000519-03 which occurs at about 2,900,000 seconds (33.6 days)(Reference 8). These calculations define the match point at which all the pressurizer auxiliary spray is boiled off. There is a longer time period required for the core power to drop below this match point such that there is excess flow that can initiate a small reverse core flow sufficient to dilute the core concentration.

N Credit for reverse core flow initiated by the pressurizer auxiliary spray is not guaranteed even though the flow rate is sufficient to remove the core decay heat. The auxiliary spray enters the pressurizer, and flows into the hot leg pipe. This low must pass over the hot leg nozzle gap before it enters the upper plenum and reaches the core. If the hot leg nozzle gap is open, it will possibly pass some or all of this injection flow rate out of the hot leg nozzle gap. In most cases the flow from one hot leg nozzle gap may be sufficient to bypass nearly all of the flow that was intended to dilute the core boron c.,oncentration. In fact, the pressurizer auxiliary spray may hinder the boron dilution that was available prior to the initiation of the spray injection. For these reasons, the pressurizer auxiliary spray method should only be used in the long term (about 34 days post event) on indication that core boron dilution methods are not diluting the core boron concentration.

If the sump concentrations and or other measurements indicate that the reactor vessel nozzle gaps dilution flow is not working and the auxiliary spray flow is equal to or greater than the decay heat boil off of all of the pressurizer auxiliary spray then the auxiliary spray method may be effective in controlling the core boron concentration.

6. REACTOR VESSEL FLOW PATHS FOR HOT LEG INJECTION Hot leg injection can be performed by reverse flow through the decay heat drop line as described in Sections 2 and 3 above and also potentially by the auxiliary spray. A net hot leg injection flow (injection fiow minus nozzle gap leakage) into the reacto; vessel upper plenum can provide dilution of the boron by mixing with the boron rich upper plenum fluid. Reverse flow of boron rich fluid down through the core barrel-baffle region or cold fuel channels and up the downcomer and out of the reactor vessel as 33

51-5000519-02 shown in Figure 11 will provide dilution of core boron. This is the dilution flow path when the hot leg irhetion flow is not large enough to overcome core boiling. Net

reverse flow through the core as shown in Figure 12 is expected when hot leg injection flow is sufficiently large to exceed boiloff. The net reverse flow through the core cools the core and controls the boron concentration by dilution of existing boron concentratiori, if any, at the time of core flow reversal.

The following discussion relates to the hot leg injection / boron dilution flow path in the reactor vessel (Figure 11) prior to complete suppression of core boiling.

The decay heat dropline is connected to the RCS hot log pipe at an elevation slightly above (4.7 inches) the elevation of the bottom of the hot leg pipe (Reference 3). (The hot leg injection nozzle is located within the start of the bend of the hot leg 90

• elbow).

The inner cylinder of the upper plenum assembly directly opposite the hot leg nozzle has 24 - 3 inch ID flow holes in addition to the larger flow holes-(6-34 inches ID and 4-22 Inches ID) located in the upper parts of the plenum cylinder (Reference 3). From the small holes opposite the hot leg nozzles, the hot leg injection flows to the upper plenum where it to mixes with core outlet steam and water. The saturated, boron rich injection fluid then flows down, by virtue of static head, to the top of tne core where it enters the flow holes that direct flow into the region formed between the core barrel and the former plates. There are 24 flow holes spaced around the periphery of the upper rue plate that provide the flow area for downflow of the injection fluid to the core barrel / baffle region. Within the core barrel / baffle region there are 8 former plates, each with 80 flow holes (Reference 6). Frora the barrel / baffle reglen the flow exits to the

_ periphery of the lower core plate where there are 64 flow holes arranged around the periphery of the plate (Reference 4). From the lower core plate the fluid enters the lower sections of the reactor vessel and then flows up the downcomer to exit the reactor vessel by way of the affected cold leg. At 500 gpm the dynamic pressure drop  ;

through the flow path described above is about 5.4 inch"s of water as calculated in Appendix 2. The head to provide this flow is developed by the injection fluid in the hot  ;

34 l

51-5000519-G2

\ .

( leg and the entrance to the upper plenum.

. 7. CONCLUSIONS Evaluations of core and sump boron concentrations have been performed for ,

LBLOCAs and SBLOCAs. Under the most conservative assumptions (ANSI 1971 Decay heat with 1.2 multiplier and the B&W heavy Isotopes), boron concentrations can reach the solubility limits within about 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> for LBLOCAs. An active mitigation process such as hot leg injection or durnp-to-sump can reduce and control the boron concentration to well below the solubility limits.

If boron is concentrating in the core region, the sump boron concentration for the LBLOCA will change about 600 ppm over the first five (5) hours post -LOCA.

Boronometer measurements along with reactor and reactor building pressure, incore temperature measurements and RCS temperature measurements, can form the basis for actuation of dump-to-sump, hot leg injection or auxiliary spray methods of core boron dilution. The limiting SBLOCAs, by virtue of longer (than LBLOCA) time at elevated RCS temperature and pressure have higher boron solubility limits and have more time available to detect concentration of boron in the core. For the SBLOCAs changes in sump boron concentration appear to be a valid indication of core boron buildup. The relationship of the difference be' ween the initial BWST boron concentration and the sump concentration or tha reistionship between the " average boron concentration" and the sump concentration versus RCS temperature, subject, to measurement uncertainties, offers a' valid core boron concentration indicator.

Hot leg injection by reverse flow through the decay heat drop line at 500 GPM offers a positive and rapid means for reducing and controlling core boron concentration buildup.

The flow areas within the reactor vessel for the hot leg injection flow are sufficiently large to offer little resistance to the injection flow paths. Dump-to-sump is also a viable means to provide positive and rapid control of core boron concentration.

35 )

51-5000519-02 i

_-b^

a Hot leg noule gaps gier a passive means for post-LOCA core boron control. The

- performance of the noule gaps for boron dilution can be inferred by indirect observations, such as long term changes in the sump concentration. Initial reliance on nonle gap dilution control can be used for SBLOC/a because of the higher temperatures and the longer time required for core boron concentrations to reach boron solubility limits.

8. MAJOR ASSUMPTIONS The major assumptions used include:

. The BWST volume is 350000 gallons.

. The BWST boron concentration is 3000 ppm This is the improved Technical Specification (Reference 12) upper limit for BWST boron concentration. Larger values of boron concentration are used to determine conservative boron concentrations in the core.

. The RCS volume is 11500 ft'.

. The RCS initial boron concentration is 3000 ppm.

. The CFT volumes are 8005 gallons each (1070 Ft' each). This value is the maximum water inventory from the CR-3 Improved Technical Specifications (Reference 12).

. -The CFT boron concentration is 3500 ppm. (This is the CR 3 Improved Technical Specificatwn (ITS) (Reference 12) upper limit for CFT boron

oncentration.

The core volume for LBLOCA boron concentration is 790 Ft'. FTl will use this value for all cases unless requested to use the SBLOCA ccre volume. This is a relatively low core volume used to conservatively predict core boron concentrating rates during core boiling following LOCAs.

Boron solubility versus temperature is as given on Table 1 from page 81, table 10 of Reference 1.

The hot leg injection flow rate (reverse flow through the decay heat drop line) is 36

51-5000519-02 assumed to be 500 GPM. This value is believed to be slight!/ conservative in that it provides a minimum of about 100 gpm net hot leg injection flow assuming the hot leg nozzle gaps are flowing up to about 200 gpm and with about 200 gpm core boiloff .

. The injection flow to a core flood nozzle is assumed to be 1000 GPM. (This value is used as an indicstor that the HPl injection pumps can be secured. This value is conservative because during a LOCA a significant amount of this flow can flow out the cold leg nozz!e back to the sump. Decay heat removal is by core boiling. The HPl pump flow requirements for SBLOCAs are def:ned in Reference 11.)

. The injection water temperature to either the core flood nozzle or the hot leg is assumed to be 140 *F (from Reference 10).

. The decay heat relationship is assumed to be 102% of 1.2 times ANS 1971 plus FTl heavy isotopes. This decay relationship is believed to be very conservative because of the long term operation assumptions and the heavy isotopes. FTl believes that a value of decay heat of 70 to 90 percent of this relationship is more correct.

. Enthalpy, temperature and pressure relationships will be cbtained from the 1967 or later ASME Steam Tables.

9. REFERENCES

1. FTl 32-1266110-00: "B&WOG Post-LOCA Core Boron Dilution"

2. FTl 51-1266113-00:" Post-LOCA Boron Concentration Management"

3. FTl 51-1212232-01: " Key Elevations for All Plants

4. FTl (B&W) Drawing : 02-142923E-04: " Lower Grid Top Rib Section

5. FTl (B&W) Crawing : 02-142917E-04: " Upper Grid Rib Section"

6. FTl 51-50C0396-00: "RVI Baffle Bolt Safety Assessment"

7. Meyer, C.A., McClintock, R.B., Silvestri, G.J., and Spencer, R.C. Jr.;

" Thermodynamic and Transport Properties of Steam", ASME,1967.

8. FTl 32-1258134-00: " Decay Heat for LOCA Analysis" 37

51-5000519-02

• 9. Florida Power Corporation Drawing s-521-038: " Reactor Building Sump, Liner, Screen and Covers Plan, Sections and Details".

• 10. Florida Power Corporation, Nuclear Operations Engineering, Crystal River Unit 3, " Enhanced Design Basis Document, Decay Heat Removal"

11. FTl 51-1229115-03: "CR-3 HPl Flow Requirements" *

• 12. Florida Power Corporation, Crystal River Unit 3, improved Technical Specification B.3.5 Emergency Coro Cooling Systems, B.3.5.1 Core Flood Tanks (CFTs).

• 13. Florida Power Corporation l Nuclear Operations Engineering, Crystal River Unit 3, " Instrument Uncertainty Analysis For Boronometer CA-56-CI, September 10,1997.

• 14. Florida Power Corporation, Crystal River Unit 3, Calculation 188-0019,

" Instrument Uncertainties For the Tincore".

15. FTl Document No. 32-5000185-01 "CR-3 Heatup and Cooldown PT Limits", September,1997

16. FTl Document No. 32- 5000654-00: Monte Carlo Analysis: Boron Dilution, September 1997 The documents marked with an asterisk are maintained and controlled by Florida Power Corporation. Per FTl procedures, use of th'e references are allowed in safety-grade calculations with the approval of the cognizant unit manager or contract manager. The signature below authorizes the use of these I

documents for input to this evaluation.

6 dbh For t rn . Lern J.K V 9 / ash 7 Unit Manager / Contract Manager Data 38

51-5000519-02 TABLE 1 -

BORON SOLUBILITY LIMIT

.y TEMPERATURE BORON SOLUBILITY LIMIT (F) (PPM WATER) g 68.0 <

1438 104.0 7363 140.0 16785 176.0 29592 212.0 50314 226.0 50467 x

242.0 72089 260.1 87930

.t 277.3 108128 289.9 128548 304.7 156751 318.9- 193721

.e 326.1 231771

^

333.1 280489 39 n

Framatome Technologies Inc.

TABLE 2A. Case t Spread Sheet for Detemuning the Sump Concentration Difference A!! awed VerSuS RCS Temperature.

Inputs l

BWST Concerdration Mcoppm barantwater , Core Mbdng VtArne

~

l CFT Contentratier. 3500 ppm baronArater 190.5y .

DC Uquid voksne 1285 23

• PCS Cswe.6. 3000 ppm boronAvater BWST L4M Vodume 35'000 gaf RCS Uguld Volume 11500 23 CFT UqtM Volume 2140 S3 RCS Average L4dd Derc2y 411, ihm/R3 ]

CFT LbH Dersty 61.5 Ewn/53 BWST todd Density 62.4 twit 1:3 ~ Berat Error < 1008 ppne Slope ppm 1006 615 0.006107 error 67.7 65 3 Borori Err t'>= 101 ppm ppm 409) 1008 0.065412 errer 2693 67.7' Calcadations 1.4M Baron Terriperature Uncertainty Shift cf: 43.5 F Mass Mass TotalMass Cornervaden

• Otwn) Obm)

BWST InMal Mass. Ibm 2919786 8759 0 mas ppm in core at 14.7 psia RCS InlBat Mass. lbm 477250 1432 47282 R)rn core water at 14.7 psla CFT ir:itta1 Mass.lbm 131610 461 l Tetal Mass 3528646 10652 3019 Mixed-mean averu9e baron concentraGon. ppm I

RCS Saturated Core Sat Uncer1Ml.

Core Core Boron DC Sat Sump DC and BWSrto ,*a. Baron Ave. Boron Boron Saturation Uquid Liqdd Solu 2ty Mass at Uguid thcertainty Uguid Sump Sump Conc to Sump l Temp Spec Vor Mass Umit Sat umit to Sump thcertainty Miusred Mass Mass Concen Differen:o Dfrar*nce Ddlerence Adjustment Teneera!ure F (ft3nbm) (ppm) i Obm) Obm)  %) Obm) (ppm) (ppm) (ppm) (mm) ppm) 140 0.016293 48518 16117 782 78868 3401260 (F) 2836 164 183 -71 253 160 0.016395 46218 23691 1833 1142 78378 3402053 2732 268 286 40 180 0.01651 47880 32765 248 203 5 1569 77832 3402934 2609 391 200 0 016637 409 171 238 223 5 d7515 43319 2059 77237 3403394 2468 532 550 321 229 212 0.016719 47282 50404 2383 2435 76859 3404506 2375 625 644 420 220 0.016775 47:24 54352 223 255.5 2561 76602 3404920 2324 676 240 0 016926 695 475 220 2615 46703 67998 3178 75919 3406024 2147 853 872 663 208 s

260 0.017089 46258 88467 4092 283.5 75195 3407104 *824 1118 1135 940 191 3015 j 280 0.01726 45800 113730 5209 74450 3406397 1563 3 1437 1456 1288 170 3235 300 0.01745 45301 144554 6548 73639 3409706 1178 /

1822 1841 - 1696 14S 3433 320 0 01766 4478t? 200898 8993 72763 3411121 476 2524 2542 2478 64 363.5 330 0 01776 44510 256156 11402 72354 3411782 0 3000 3019 2957 62 1733 340 0.01787 44236 280003 12 P5 71MMI 3412502 0 3000

.fyt 3019 2957 62 383.5 ^

W A

O b

M

-c

Framatome Techriologies Inc.

TABLE 28.' Case 2: Spread Sheet for Determining the Sump Concentration Difference All 11 nede . .

swsi Conewe.sen , 22 5 p,ra mmer*,aser Cars uns vs.no CFT Concenerseon 2270 ppen boronAvetor 790_s a3 '

aCs Concewmen DC Uguid Voksne 128t5 R3 2no ope ner ,*,mer swsT Up voi.no 350 m Sar aCs up voksne .11500 m3 ..

CFT Uguld Vo4wne 2140 R3 aCS Aversee Uguid oenemy 41.5 aunt.u CrTu suidoener 61.5 enwa3 awsTUguid oenemy 82.4 nuwa: Bomn Ecr < 1008 ppe Simpe opm 1006 -

. 615 error .a.00sto?* '

'67.7 65.3 -> *! ^

Seren Erwer >= 1008 ppm ppm 40001 100t 1 085412.

e ror ~69.3 c* ' _ .a - 67.7

, Uguid Baron Mass ' Mass Temperature Uncastakey SNR of:

TotalMass conservason . 42.5 F '

. (twn) Utum)

BwSTinnlaiMass. ten 2919786 6628 RCS inhief Moss, twn 0 men ppeln core at 14,7 pela 477250 1083 CFTinidal Mass, kun 47282 8mn core traser at 14.7 psie 131610 299 Total Mass 3528646 e110 2270 bEmedanean awarage baron concentranonJ9m RCS Saturated CoreSat Core Core Baron DC Sat Sump UhewtA4 ,-

Saturation Uquid uguld Solubility Mass at DC and LW3Tto* k. .3eren Ave. Baron Uquid Lktd1 Baron thcertainly Ternp Spec Vol Mass Lknit Solumit Sump Su g conc to Sawnp F htass Mass to Sump tJhrertainty A4; seed (43Atwn) gtwn) (ppm) Corran 140 0 016293 48518 Stwn) (2Nn) porn) (ppmi Dulerence D6fference Dulerance Adjustment Teriperature (rpm) ' (ppm) 16117 782 (ppm) dysn) '

160 0.016395- 48216 78868 3401260 2077 193 (F) 23691 1142 193 .it 204 180 0.01651 78378 3402053 1973 297 183.5 47800 32765 1569 297 100 19' 200 0.010637 77832 3402934 1851' 419 203.5 47515 4:339 2059 419 231 189 1 212 0.016719 77237 3403394 17f5 561 223.5 47282 50404 2383 561 381 100 220 0 016775 76859 3404508 1816 654 243.5 ,

47124 54352 2561 654 480 76602 3404920 15G5 173 255J5 240 0.016926 56703 M996 3176 705 705 535 75919 3406024 1388 170 263.5 ,

260 0.017059 46258 88467 882 882 723 4092 75195 3407194 159 283.5 i

280 . 0 01726 1125 1145 45800 113730 $209 74450 3408377 1145 1004 141 303.5 300 0n1745 804 1466 45301 144554 6448 73639 3409706 1486 13)9 66 323.5 _g'

'320 0.01766 420 1850 ,1850 44762 200098 8993 72763 3411121 1786 -

64 343.5

. a 330 0.01776 0 2270 2270 44510 256156 11402 72354 3411782 2209 62 363.5 [n '

340 0 01787 0  ::210 44236 280000 123J6 71908 3412502 0 2270 2270 2270 2209 2209 62 - 373.5 - Q 6

62 383.5 Ut a.

A -6 n

,, ., . e in ' e '

l l

i Framatome Technologieis lac.

TABLE 3A. Casa 3: Spread Sheet for Determining the Sump Conc:ntration Difference A!! awed VerSuS RCS Temperature.

Inputs BWST Concentrason 3000 rpm borarenster Core Ering Vol _s i .

CFT Concentration 3500 ppm baronArater '

790jf!3 DC Uquid volume 1285 ft3 RCS Cmcestration 0 ppm baronArater B;WTUguitf Volume 350000 gal RCS Liquid Volume 11500 u

_ CFT Uguid Vokame 2140 ft3 RCS Average Uquid Densey 41.5 !bm/ft3 CFT Ugu6d Denvfy 61.5 tbmfft3 Boren Error d1008 ppm Slope BWS1 Uguki Densky 62Astwrsit3 ppm 1006 615 0.006107

• rror 67.7 65.3 Baron Error = 1008 ppm ppm 4090 1008 0465412 error 269.3 67.7 Calcufations LkyJid Baron Temperatiare tJncertainty Shift of: 43.5 F Mass Mass Total Mass Conserva* ion * (1bm) (Ibm)

SWST Initial Mass. Ibm 2919786 9759 0 max ppn. In core at 14.7 psia RCS trdGalHass, bm 477250 0 47282 lbm core wafer 3114.7 psta CFT Initial Mass, Ibm 131610 461 Total Mass 3528646 S220 2614 Mixedeean avera9e boron concentration. ppm tJncert Adl.

RCS Saturated CoreSat Core Core Baron DC Sat Sump DC and BWSTto* Ave. Baron Ave. Boron Saturation Uquid Baron Uncertat.!y Uguid Solubitify Mass at Uquid Uquid Sump Surnp Cone to Sump Temp Spec Vol Mass to Sump tJheertainty Adjested umit Solumit M.ss Mass F Concen Difference Difference Difference Adjustment Temperrtum (ft3/tbrn) (1bm) (ppm) (!bm) (1bm) (pprn) (ppm)

(1bm) (ppm) (ppm) (ppm) 140 0.016293 '8518 16117 782 78868 3401260 (r) 2425 575 183 -38 226 160 0.016395 48216 23691 1142 1835 78378 3402053 2321 679 292 72 220 180 0.01651 47880 32765 203.5 1569 77832 3402934 2198 802 415 203 211 223.5 200 0.016637 47515 4"#39 2059 77237 3403894 2057 943 556 354 202 243.5 212 0.016719 47282 50404 2383 76859 3404506 1964 1036 649 453 196 255.5 220 0.016775 47124 54352 2561 76602 3404920 1913 1087 700 508 193 263.5 l 240 0.016926 46703 67998 3176 75919 340G024 1736 1264 P77 696 181 2835.

260 0.017089 46258 88467 4092 75195 3407194 1472 1528 1146 976 164 303.5 280 0 01726 45800 113730 5209 74450 3408397 1152 1846 1461 1318 143 32 1 300 0.01745 45301 144554 6548 73639 3409706 767 2233 a

• 846 1780 66 343.5 320 0.01766 44762 200898 8993 72763 3411121 65 2935 M 2548 2486 62 363.5 330 0.01776 44510 256156 11402 72354 3411782 0 3000 O

2613 2551 62 373.5 I

t 340 0.01787 4423S 280000 12386 71908 3412502 0 3000 2613 2551 62 383.5 O

01 h O t

FO to

u < ., s 7 y ; _, . + s.m ~ ,~ . .- . .

,. 3 y ' ..,

i :--

rC .x

,a.

a

=

8 '.-

t o . .

g T .

a ABLE 38. Case 4:- Spread Sheet for Determining the Sump Cersiai. tion Di5erence Allowed Versus RCS Te l Inpeile e L' a

_s v <

1 BWST Concentraean 2270 ppna borenAmeter , ,

, Case teming Valwne 790.5 R3 ,

j2270 CFT Concentraean ppna besenAmeser  ? y ~

DC Ugukt Vehnte 1295 e3 4 ' ftCS Concentsaten o ppse besen4seter 2 J- -

SWST 8jgidd Vaewne 350000 Sol -

• - RCS Uguld Volwee ,

.A pl:~ . . J 11S00 R3 -

- . CrT uguM, Veenne 214e a3-

.. - HCS Average 8 bred Doneer . .. ;41.5

^ >.

knam3 l -

'

• CrT nyde Denmay ' ~

et.s andt3 ,

i BWSTUguid Denmar .>

42.4 mudit3 . essen Ener < 1600 ppm . . Sepe 1 ppna - 1000 .;

615  ; 8.008111F ener' g

. 67.7 u e5.3 : ? ~ r- -

Sesen Esser p 1000 ppen ppna '4000 'i

1908 : ' 8.885412 i ener- 47.7 ,-

' 200.3 f

=hdanans p ~ Uguld

. Bosen

'@ Moss Moss TesnpereeweL '

M r' .SURafr  ::43.5 F ,

- TotalMoss Cn_ "

(aun) gtwn) -

. SWSTinitet Mass. Rwn 2919706 0628 HCS InitsiMoss, Own 0 meer ppm he cose at 14.7pois, 477250 '0

. CFTintleiMess, tun'- 47202 tun case weser at 14.7 pale

_ 131610 _299 r,

TotalMass _. .

352d646 6927

?

1983 Mised-sneen average boren-:

" Jipsn 7- '--' "

a T RCS'. Saturated Core Sat Core . Case Baron DC Sat Senp DC and SWSTte* Ave.Beren Ave.Desen Saturation Uqidd ~ : Uguid MW teess et Uquid Besen l. 8A- - ,

~ '

'_ i Tesnp 1. Spec Vol Moss 1 Limit Lk:uld ' Sump ' Sienp Conc le $nanp ., ' to Seenp '" A$seted F

SeeLimit . Mass Moss . ,

.i *

(a3ewn) - plun)  ;(ppm) . (Itun) Canoen 00lesence DWesence DWesence A$ssement Temperesuse '

Otwn) ptwig (ppm) . ppni) Gysn) -

140 0.016293 48518 :14117 ppa $  : ppa $

_782 70068 3401200 1798 - 504 (F) 160 0.014395 ' 48216= 23691 197- ~ 14 . 183 183.5-1142 78378 '3402053 1962

100 0.01651- 806- 301 125 47000 . 32765 1569 '77832 3402934 1539 178 203.5 >

731 424 255 168 - t

~ 200'D.016637 - -47515 ' 43339 2059 77237 3403094 1398 :f 223I 212 - 0.016719 - 47282 872 565 406 -159.

'50404 2383 78859 3404505 1305 '243 *

-220 0.016775 47124' 965 658 505 - 153-54352 ' 2561' 78002 3404920 256.5 '

1254

~

240'O.016926 '46703- 1016 709 559 150 67990 3176 75919 3400024 283.5 1077 1193 SOS 748 200 0.017009 " 46258 88467 4092 75195 3407194 138 203.5 .

814 1456 1949 '1003 200 ' O.01726~ '45000 i66 113730 5209 74450 3408397 3035 300 - 0.01745 45301 :144554 8544 73639 3409708 493 1777 1470 '1405 65 ~ 323.5 :m - ' '

l

~f tot 2161 1854 320 0.01706 44762 200090 8993 72763 3411121 1792 82 343.5 '

0 2270 1983 1901 4

' 330 s 0.01778 44510- 256156 11402 82 - 383.5 .

72354 3411782 0- 2270 1983 a

340 0.01707 44236 200000 :12308 71908' 3412502 1901 82 373.5 -

0 2270 1983 1991 82 - 303.5 "

a @. h

.- (d s; ,

PJ '

r 1 .

, p., J *

. . , . - ~ . . - , . . _

v- - - . - ._-.,,,..a , . , . ~.

p - - y c-  :

~

Framatome Technologies Inc. ~ o

% G

.. TABLE 3C. Case Si Spread Sheet for Determining the Sump Cor.:antration Difference ABowed Versus

' impues -

4 swSTC ncmaramon -2270 pps twar*mer CFT Conconeramon ; Core meno vw.ne 7903 a3

'227e ppse borer*resor ~ DC Ugtid Votane nCS Concenwaeon 0 ppm beror*mer 1285 6s swSTuges venan. - -

RCS Ugukt Volume 11500 R3 .

CFT Uguld Vohane '2143 R3

'RCS Average Uqdd Dens 8y 41.S Sun /R3

. CFTuguid Denser 81.5 endt3

'i swsT Uguid Dene8y 62.4 ensts Baron Ener< 1008 ppm . Stepe

. ppm 1063 615:

e.008107 error - 67J 65.3 Boron Ener u 1008 ppm _

,. ppm , 4090 1008 0.0054i2 error 209.3 47.7

~ -

Calcada6 ens Uguid Bornn Mass Mass Temporalwe uncertainty Shit of: 43.5 F - '

TotalM ss Conserva8on - Otwn) (Ibm) '

8WSTInital Mass.Rwn 2085561 4734 RCCIniSalMass,Run - 0 mas ppm in core at 14.7 psia

-477250 0 CFTIn81st Mass,Rwn 47282 Swn core water at 14.7 psee 131610 299 '

TotalMass . 2694421 5033 F

1868 n8 sed-mean average baron concentration. ppm

' RCS Saturated Core Sat ~ Core Core Baron DC Sat Sump Uncert A4 Saturadon Uguid DC and Uguld MW Mass at Uguid Uguld SwSTto* Ave. Baron Ave.Beren . Baron Uncertainty -

. Tarnp Spec Vol Mass Sump ' Sump Cone to Sump to Sump - W -- L. , Aquesed Umit . Soittnit Mass Mass F- (83atun) Otwn) (ppm) . Concen Dillerence Deerence Disorence Adjustment Temperatwo Otwn) Otwn) Otwn) (ppm) { ppm) 140 C.016293 48518 (ppm) (ppm) (ppm)

.16117 782 78666 2567036 (F) 160 0.016395 1907 663 261 , 88 48216 23691 1142 78378 2567828 .173 183.5 '

1470 800 398 180 0.01651 47880 32765. 1569 234 164 '.203.5

' 77832 2586710 1309 961 559 200 0.016637 47515 43339 .2059 40G 153- 223.5 77237 2589888 1123 1147 744 212 0.016719 47282' 50404 2383 803 141 243.5 -]

76859 2570281 1001 1289 867

, 220.0 011775 47124- SC52 799 68 255.5 2561 -76602 2570806 934 1336 934 240 0.016926 46703 67998 3176 867 67. 2ti3.5 75919 2571799 701 1569 1168 260'O.017089 46258 88467 4092 1101 66 283.5 75195 2572989 355 1915 1280 0.01726 45800 113730 5209 1513 1449 64 303.5 74450 2574172 0 2270 Ut-300 0.01745 45301 144554 1868 1808 62 323.5 320 0.01766 44762 200898 6548 8993 73639 2575482 0 2270 1888 1806  : 62 343.5 Y*

72763 2576896 0 2270 1858 330 0.01778 44510: 256156 11402 1806 '62- 383.5

~72354 2577556 0 2270 1868 340 O_01787 - 44238 280000 12386 1806 62 3 73.5 .

71908 2578277 0 2270 1888 g 1808 62 303.5 "-

a N b 6:

'N

, 'Y .f

_ _ . _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . - _ _ . _ _ _ ___ . _ , c . .+ m .., , , ~_

51-5000519-02

-I

- TABLE 4 -

l LBLOCA CORE BORON CONCENTRATION

- FOR DILUTION BY HOT LEG INJECTION 400 GPM NET HOT LEG INJECTION FLOW Ccore DCMB MCB Core Boron Time Delta Core Mass Mass of Core Boron Concentration (seconds) (Ibs) (Ibs) (ppm) 18000 -

2376.8 50300 0 18500 1254.6- 1122.2 23750.3

- 19000 528.5 593.7 12564.6 19500 222.5 371.2 7855.7 20000 95.8 277 4 5870.6 20500 39.5 247.9 5246.3 21000 22.4 225.5 4772.3 21500 9.4 216.1 4573.4 22000 4.0 212.1 4488.7 L

45 L

l l - . . - --_

+

I 51-5000519 4 2 TABLE 5 LBLOCA~ CORE BORON CONCENTRATION 4

FOR DILUTION BY HOT LEG INJECTION:

100 GPM NET HOT LEG INJECTION FLOW .

. Ocore.

DCMB MCB Core Boron Time Delta Core Mass Mass of Core Boron Concentration (seconds) (Ibs) (Ibs) (ppm) 18000 2216.8 50300.0 19000 570.0 1646.8 34851.4 20000- 358.4 1288.4 27266.6 21000 254.5 1033.9 21880.6 22000 180.7 853.2 180L. .

23000 128.2 725.0 15343.3 ,

24000 91.1 633.9 13415.3

. 25000 64.7 569.2 12046.0 L

S 46

. . .. . , , ~ . . _ , - -

51-5000519-02

~ TABLE 6 -

9

.SBLOCA CORE BORON CONCENTRATION FOR DILUTION BY HOT LEG INJECTION:

-s:

400 GPM NET HOT LEG INJECTION FLOW Ccore DCMB MCB Core Boron Time - Delta Core Mass Mass of Core Boron Concentration (seconds) (Ibs) (Ibs) (ppm) 360000 8228.2 120000.0 360500 3183.9 504403 73566.4 361000- 1913.9 3130.4 45653.4 361500 1150.5 1980.9 28889.3 362000 691.4 1289.5 18805.8 362500 416.2 873.3 12736.3 363000 250.2 623.1 9087.3 363500 150.4 472.7- 6893.9 364000 90.4 382.3 5575.5 364500 .54.4 327.9- 4782.1 m

47-

51-5000519-02

.s,.-

4. t

- TABLE 7--

TU- *

, SBLOCA CORE BORON CONCENTRATION FOR DILUTION BY HOT LEG INJECTIONf w 100 GPM NET HOT LEG INJECTION ' 8 OW '

s.

Ocore DCMB MCB Core Boron

. Time "' Delta Core Mass Mass of Core Boron Concentration (seconds) . (Ibs) _ -(Ibs) (ppm)'-

360000 8228.2 120000 361000 15780.8- .6657.4 97091.9 362000 1257.0 5400.4 78759.8 363000 1005.8 . 4394.6 64091.1 364000 804.8 3589.8 52353.9

, 365000 644.0 2945.8 42961.7 366000. 515.4 2430.4 35445.1 367000 412.4 2018.0 29430.6 t

I 368000 .320.0 1688.0 24617.9 369000 264.1 1423.9 20766.2 370000 211,3 1212.6 17684.6

371000 169.1 1043.5- 15218.5 372000- 135.3 908.2 13245.2-i N

1!

m v

b mYwOgO$@6" 5

3 0

3 E

M T'.

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)

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! I1  ! , l!(l: llliIl,l

51 5000519-02 FIGURE 2 REACTOR VESSEL ARRANGEMENT mmmmmma 6_ = = = = = = a

[ ,

g _

~

I - -

I_ -

~_ _ _N . I _B S jJA

~

su . _ _ _!! ,

gO OOU 24,21 A -

' 23.94 h 22.42 A- t

$ \ k -22,75 A

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, [ l' -

-21.25 A 20.00 h-  ; Id '

{ -19,75 h

_ . _ . . . . _ _ _ _ =-

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... g a / m-y /

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+

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1HIDDl1 HlWI l i ip 1--,,,

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,, ,, u ,

1 tv-- y y

\ g .

I NNN I I 50

51 5000519-02 FIGURE 3 REACTOR VESSEL UPPER PLENUM MIXTURE LEVELS if l

RW/ RVW ,

eam Upper . steam y- f Plenum q .

0 00 U OO Oo j O OO -Q- m - -

00 .}

e gO((

Cold '

O o D ** I -

Leg j'O O o (;/ Hot Leg

. goo h g00 0 OO p$

o 0 ,

O 00 4

j'u O

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o oA O o

o O O

@ j to O 0 00 m O O oO O O Steam Dubbles from Core 00 O j F U l

51

Figure 4A. Case t BWST to Sump Cars."e" en J Difference versus RCS Temperature with BWOT at 3000 ppm, CFT at 3500 pm RCS at 3000 ppm, and 350000 gal BWST.

3000.0 t^

2500 0 s --

NNW t DW 2000.0 7 '

I T

E -

t 15000 i b E

E O 1000.0 I

Ace op.,m..

/

0.0

// :.

seo 200 220 240 - 2s0 2s0 300 220 se aso m in a

4 acs saturamon Temp (F)

! m 5-NaD'AisiL-samp --5-$'as5MTUsamp g

i N 6 4

Figure 48. Case 2; BWST to Sump Concentation Difference versus RCS Temperatawe with BWST at 2270 ppm, CFT at 2270 ppm, RCS at 2270 ppm, and 350000 gal BWST.

3000 2s00 6

Unacceptabe Operat.ori, inesse Aceve soren tmam r -

menement a

._ /

3 tw c .

"9" 2

E 5 1500 h

E f 5

i E

O 1000 -

. .-4

.- ^'*"*

- 7,,,.

X ~~~

4 y

0 /\

180 200 220 240 260 280 300 320 340 m

360 300 y RCS Satwadon Temp (F) *

hed-Mean Ave-Samp --4--Temo & Baron theart Aq Ave -Senp -- M --SRSS Adj Ave-Sump a

Ut m to w 6 w

Figure SA. Case 3: BWST to Sump Concentation Difference versus RCS Temperature with BWST at 3000 ppm, CFT at 3500 ppm, RCS at 0 ppen, and 350000 gal BWST.

A at g

zwo p= =

%%~.

-E 2000 Inaia!e w somacaumm g -_ _. :.L insanenent 1500  ;

r 1000 M y

/ / ~

u

/ - 0 7,.

Y

....x w o,.<=or.

If ....

y

,... * /

a

/y .

'*

• m m m m a m , 2 RCS Saturation Temp (F) g i

• _-Sump Mixed-Mean Ave -S; ,,

A Temp & Baron Uncert A4 Ave-Semp -

3 m -- X . .SRSS M M eq ,

h c O

M

m

, - + s Figwe 58.' Case 4: BWST to Sump Concentation Difference vasus RCS T% ~

with swsT at me ppm, cFr at me ppm, acs at a pp , and 3soooo gas awsr.

i-l t

'2500 i I i

- 2000 mm soren m non L

?-

j A

<"w' i _

i 4

he> w f- -

5 1500 M C "".,---

P Jr -

• C i e 1000 J

/ 7 ( .

,e

....> y. . .. .

r g -- it u

x y.... 3V...

g ,

i 0  :

t

\

200 22-1 240 i

260 280 m - a g g RCS Satursson Tesap(F)

• i m

I+7t-f

Wh h - Em + . Ternp a so en uncont Aag Ave.Susnp ..

M --SRSS M h.%

g g

m

[

i w - e  !

t s

m t

r p

,,e--. a e.i - M e sw a W-e-.- - e.-'r-.._._ T - +r- 'n--+w imm.>- ,- ,em.w. ,rg--e y +. g ey-w8-'Wst++aw- --'y a-we-- y erNere v e- ------*T----' aim. C y 9 ---sw -M T'-www-

Figure SC. Case 5: BWST to Samp Concentation Difference versus RCS Temperature with BWSTat 2270 ppm, CFT at 2270 ppm, RCS at 0 ppm, and 250000 gal BWST.

2000 -

. 2500

]

i

)

Unacceptatk Operstaan.

-E 2000 la** Acta Baron D+Aon

$- f -,

=

=. =  ::

'e p - i a

. u. - _ _._.: a 5 1500 c /

M , &stnerord

~

f f l

c o

u 1000, ,

X

' *.X*,

.. Ac6 Opernemi g l y.-

~

l 0 ,

180 200 220 240 260 280 m a g g g-- RCS Saturmelon Tone (F) o o

! " A"

• S- + 1 Temp S Boron Unart Aq Ave-sun, . . x . . sass q w, er a 6

M

FIGURE 6 LBLOCA CORE BORON DILUTION WITH DUMP-TO -SUMP (CLPD BREAK AT2568 MWt; 7.8 GPM DUMP-TO-SUMP AT4 HOURS) sooo ,

l sownyuna :o t .

M- .

I -

% 4

• 000 - / .

Core 110 I_

f 2

"'I sww 5 ~

u 3_ _

1000 M

0 ht o s to is 2o 8

o

• 25 x n me.m g N 6 u

FIGURE 7 REQUIRED DUMP-TO-DUMP Fl.OWVERSUS OPERATOR ACTION TIME 12 11 I

to h

M g _

z. -

n-

[, -+-2568Imt Saewased Somng

& a

- j

---2= = - %

3

-*-2nz uwt *-t-= :soan, 0 7

f.  :: --

6

[

5 4

On 1 2 3 4 5 6

%m--x a

_f' oi O m 6 '

4 u

51-5000519-02 i

en N

.I 6

j! 9 5

$ f E!

@ I a /

_f as l,

ie s

-e -g l\)

t. ag

t. .

8 g!

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a d

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/

a a a g a

.-.~ ~

h.- m a 3/ l e

l o L

... .... ..-. . . . . N ,

!  !  ! I I  ! N (Wdd) skontaussuos

. 4 59

51 5000519 02 ,

FlGURE 9 SBLOCA CORE BORON DILUTION WITH HOT LEG INJECTION S

j4 g _

z 8

}

@ 8 8

._ V 5

.le -

h d

8 5 n: e 8 8 x 5 =

8

, b -

h- -

- -l',k, s, -

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8 5

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p

/ /

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S -

E \' i a 8

' b \ ' $

F x

! l l l l 1 8 8 i ~

(rfdd) vuorteaussues 60

51-5000519-02 FIGURE 10 SBLOCA CORE BORON DILUTION BY REACTOR VESSEL NOZZLE GAP FLOW

-H g

r I

if / 1 i .. g

. +

7 j k

, ,- [

~

~E_

/ .- / I a

.(I =a ~

\ *

( ) L. ,

E \ l . g

$ h Il Nx /

. O

!  !  !  !  ! l 8 9 R (Wdd) vuonsflussung 61

_ , . . _ . - .1 -

51-5000519-02 FIGURE 11 HOT LEG INJECTION FLOW PATHS IN THE REACTOR VESSEL L- Control Rod Drive Mechanism r=1 t : 3 cm t:2 t 1 m v=

=

C s

=

==r

/

x-

)

- -si\ f -

r' a

JJ;

~f gg y ReactorVessel p

[g Si

(

M I

JJ0 -

7 Plenum Cylinder Inner T t 1 0

b!  % l Y  : Plenum d

• o . d c m .

f.

Cylinder Hot 4i *

~

> Leo

)

• a >

, ,, , o '

g o, ,

f'!, 4 foR N ?~

~~~

+

,_.c Upper Core i ,. .. m . ,_

h Plate f /

3 , [ n s ' l l- ,

\i 5<,$ ... ... .. ... ... . . .'l-  ;

Tn L DH Drop Line,

' ^i Hot Leg Flow Holes .j . , . ... ... ,, ,,, ... , . . l injection I

Thermal Shield > -

A ... .. ... A f

1. Downcomer Core Bartol -

f}'; ) h

.% (

Former Plates  : . . . ... ... .. ... ... . . . -l Idf r ,

Fuel Assembly Baffle Plates - gw i l kh,7 y-y-y( - yyyy, M

~

Q l / Lower Core Plate l' 9 A

~

Flow Holes ^M~ .y I J  %

4g 62

51 5000519-02 FIGURE 12 HOT LEG INJECTION FLOW PATHS IN THE REACTOR VESSEL FOR REVERSE CORE FLOW C. Control Rod

Drive Mechanism em em e

:3 cm =3 cm e == = = = = = = m

" h6}E Q-f } i

~ Y j p Reactor Vessel h .

Plenum Cylinder M t d') h0 inner T f"i d A -

Plenum o Cy!!nder g h; . . Hot g ,' ' . / Leg

+)

a

=

2 . $..k '. f^..f&. ,,,

(a'ci p er Core - 1 A EL___ M gm-.

i

F -

y, u 3 ,,m ,, s ni,,, . . . . -. -. .. _. _. . .

' DH D Line, Hot og e injection Core Barrel

_14} ... .. ... -

4 1

< Downcomer if ir Former Plates . . . ... .... . ... ... . . .

4 < Fuel Assemaly Baffle Plates - g  ;

Ce - -

g,vT "-myprr T~m r Iri.,

ki auuu Alli.

"E f i

lliY . .

, Lower Core Plate 0

p r-[

0

+F '

63

51-5000519-02 APPENDIX 1 HOT LEG INJECTION DILUTION CALCULATIONS This Appendix contains calculations of CR-3 core boron concentrations following assumed actuation of hot leg injection at 500 gpm. Hot leg injection is accomplished by reversu flow from one running LPl pump, pumping through the LPI cross connect piping, backward thrcugh the idle LPl pump through the decay heat drop line, and into the hot leg.

These deborating calculations are for two cases:

Case 1: A LBLOCA where the RCS is assumed at 14.7 psia and the bnron solubility limit is about 50300 ppm boron.

Case 2: A SBLOCA that hangs up at about 72 psla/305 F saturated. The boron solubility limit for thea conditions is about 156 750 ppm boron (Table 1).

The major assumptions common to both cares include:

. Hot leg injection flow is assumed to be 500 gpm

. Decay heat is 1.2 ANS 1971 with the FTl heavy isotopes (Reference 8)

. The BWST volume is 350,000 gallons at 3000 ppm boron

. The CFT volume is 8005 galbns each at 4000 ppm boron

. Total CFT volume is 2140 ft'

. The RCS volume is 11,500 ft', at 3000 ppm boron A1-1

51 5000519-02

• The core / planum volume used for borating/deborating calculations is 790 ft'

. The initial temperature of the BWST and CFT water is 140*F e The RCS pre trip conditions are assumed to be 580'F/2200 psia

. The temperature of the hot leg injection water is 140'F e The LBLOCA thernal conditions are assumed saturated at 212'F/14.7 psia e The SBLOCA thermal conditions are assumed saturated at 72 psia /305'F e Nozzle gap flow is conservatively assumed to be 100 gpm of the hot leg injection flow that bypasses the reactor vessel upper plenum and core outlet.

Other data used in the deborating calculations are:

l

. Water specific volume at 140'F (Reference 7) = 0.01629 ft'/lb i e Water specific volume at 14.7 psia saturated =0.016719 ft'/lb >

e Core water volume is 790 ft' e Core water mass inventory at 790 ft' and 14.7 psia = 790 ft'/0.016719 ft'/lb = i 47252lbs Case 1: LBLOCA .

The general calculation process will be to conservatively calculate the core boron mass and concentrations at each time step. The sump boron mass and concentration will be assumed to be constant , consistent with a sump boron concentration of 3000 ppm. In addition, the core boiling flow rate over the time of interest will be assumed constant at 26 lb/sec. (The boiling flow rate is nearly constant at about 26 lb/sec over the 2000 second time of interest for the deborating A1-2

51 5000519 02 calculations). The' core boron mass calmletion will be performed as described ,

below. -  !

The boron mass change for each time step will be calculated as:  ;

i

1) boron mass into the core frnm 'ha core bolling f'.m times the sump concentration,  :

i plus,

2) the not hot lag injection flow of 400 gpm (500 gpm hot leg injection minus the [;

assumed reactor vessel nozzle gap flow of 100 gpm) times the sump concentration ,

. of 3000 ppm, and, f I

3) minus the not hot leg injection flow of 400 gpm times the core boron concentration at the beginning of the time step.

Core boron concentration is calculated from the core boron mass at the end of each  ;

time step divided by the core water mass, in equation form the boron tv. ass change  ;

Is:

DMCB= delta mass core boron, Ibs MCB= [Wb

• Csump + Nhli

• Csump - Nhli

• Ccore]

• Dt/10' Where:

Wb n core boiling flow rate, assumed constant at 26 lb/see t Csump = sump boron concentration, ppm boron, assumed constant at 3000 ppm Nhli = Net hot leg irjection flow of 400 gpm (500 gpm flow into the hot leg pipe from the decay hea! drop line minus assumed 100 gpm leakage through the  ;

A1-3

51 5000519 02 reactor vessel inlet nozzle to the dovncomer.

Ccore = Core boron concentration, ppm boron Dt = Time step, seconds 10' = ppm per Ib By assuming that the boiling flow rate is constant, that the sump boron concentration is constant, and that the time step is 500 seconds, the equation for change in core boron mass:

DMCB= (Wb*Csump+Nhli'Osump-NHli'Ccore]*Dt/10' , reduces to:

DCMB = [26lb/sec

• 3000 ppm + 54.7 Lb/sec

• 3000 ppm - 54.7 lb/sec

• Ccore),

or DCMB = [121.05 lb - 0.02735 lb/ ppm

• Ccore)

The initial core borore concentration is assumed to be 50300 ppm, the boron solubility limit at 212 F/14.7 psia (Reference 1). The corresponding initial core boron mass is:

8 50300 pprn

• 47252 lb /10 ppm /lb = 2376.8 lb.

The core boron mass with time is the core mass at the beginning of the time step time minus DCMB of the time step. The initial core boron inventory is 2376.8 lb at 18000 seconds A1-4

5105000519-02 ,

The core boron concentrationis:

Ccore = (Core boron mass, Ibs / Core water mass, Ibs)*10' ppm /lb, ppm Using the DCMB equation above: DCMB = (121.10.02735

• Ccore)  ;

The results of the first time step 18000 to 18500 sec is shown below:

DCMB = (121.1 ppm - 0.2735 lb/ ppm

• 50300 ppm) = 1254.6 ppm Core boron mass = 2376.8 lb - 1254.6 lb = 1122.2 lb and the core boron concentration is:

Ccore = 1122.2 lb / 47252 lb

• 10' ppm /lb = 23750.3 ppm Fe!!owing this process, the core boron mass and concentration with time are i

calculated as follows:

d 2 Time step,18500 to 19000 see DCMB = (121.1 lb - 0.02735 lb/ ppm

• 23750.3 ppm) = 528.5 lb CMB = 1122.2 lb - 528.5 lb = 593.7 lb Ccore = 593.7 lb /47252 lb *10' ppm /lb = 12564.6 ppm 3* Time step,19000 t's 19500 sec DCMB=(121.1 lb - 0.02735 lb/ ppm

• 12564.6 ppm) = 222.5 lb CMB: 593.7 lb - 222.5 lb = 371.2 lb A1-5

. . a .. ~ - - . - _ . . .. , . . . . . - . - . - . - -- .=. . . - - _ . . . - . - . .

51-5000519-02 core = 371.2 lb / 47252 ib

• 10' ppmab = 7855.7 e

h 4* Time step,19500 to 20000 sec DCMB= (121.1 lb - 0.02735 ppm /lb

• 7855.7 ppm) = 95.8 lb CMB = 371.2 lb - 05.8 lb = 277.4 lb .

Ccore = 277.4 lb /47252 lb

• 10' ppm /lb = 5870.3 ppm j 5* Time step,20000 to 20500 sec  :

DCMB = (121.1 lb - 0.02735 ppm /lb *5870.3 ppm) = 39.5 lb CMB = 277.4 lb - 39.5 lb 247.9 lb Ccors = 247.9 lb / 27252 lb

• 10' ppm /lb = 5246.3 ppm 6* Time step,20500 to 21000 see DCMB= (121 1 ' .b - 0.02735 lb/ ppm

• 5246.3 ppm) = 22.4 LB CMB = 247.5 .u - 22.4 lb = 225.5 lb .

Ccore = 225.5 lb / 47252 lb

• 10' ppm /lb = 4772.3 7* Time step,21000 to 21500 sec ~

DCMB = (121.1 It. - 0.02735 lb/ ppm * / 772.3 ppm ) = 9,4 'b CMB = 22SE lb - 9.4 lb = 216.1 lb Ccore = 216.1 lb / 47252 lb

• 10' =4573.4 ppm i

A16

. . - - - - _ = - -. - ._- . .-- . - . _. -- -._ -

l l

51 5000519-02  ;

8" Time step,21500 to 22000 see -

DCMB = (121.1 lb - 0.02735 lb/ ppm

• 4573.4 ppm) = 4.0 lb CMB = 216.1 lb-4.0 lb = 212.1 lb Ccors = 212.1 lb / 47252 lb

• 10' pp  : 7 ppm The changes in boron concentration and mass with time as shown above indicate that hot leg injection is a valid core deboration rnethod. A tabulation of the results of . '

this calculation are shown in Table 4 in the main body of this d.)cument.

In addition to this case, it is assumed that 400 gpm of the 500 gpm hot leg injection flow bypasses the upper plenum by flowing to and through the reactor vessel nozzle

_g aps. The following deboration case uses 100 gpm hot leg injection dilution flow and the core boiling flow rate is assumed to be constant at 26 lb/sec as used for the 400 gpm hot leg injection case.

The net hot leg injection mass flow rate at 100 gpm is:

100 ppm /7.48 Ft'/ gal /0.01629 Ft*/lb (@ 140 F: Reference 7) =13.7 lb/sec The DCMB equation becomes:

[26 lb/sec *3000 ppm + 13.7 lb/sec* 3000 ppm- 13.7 lb/sec

• Ccore)

• i L1000 sec/10' pprn/m]

A1-7

• w - pww --we*-er*, - y

e s a b- - .n- e 51-5000519-02 DCMB=[78 lb + 41.1 lb + 0.0137 lb/ ppm

• Ccore), Ib

= [119.1 lb -0.0137 lb/ ppm

• Ccore) i Two time steps will be used to illustrate the boron dilution calculation process:

/ 9

\

1" Time Step , i DCMB= 119.1 lb - 0.0137 lb/ ppm

• 50300 ppm = 119.1 lb-689.1 = -570 lb r MCB= 2216.8, Ib - 570 lb = 1646.8 lb Ccore = 1646.8 lb N7252 lb

• 10' ppm /m =34851.4 ppm 2* Time Step -

DCMB= 119.1 lb - 0.0137 lb/ ppm

• 34851.4 ppm = 119.1 lb -477.5 lb = 358.4 lb

! MCB =1646.8 lb - 358.4 lb = 1288.4 lb Ccore = 126a.4 lb /47952 lb *10' ppm /m =27266.6 ppm Following this calculstion method boron dilution for 100 gpm net hot leg injection is developed as shown in Table 5 in the main body of this document.  ;

I Case 2: SBLOCA .

Deborating calculations are performed for a SBL DCA, assumed to be at 72 '

L psla/305'F to show the capability of hot leg injection. The hot leg injection flow assumptions are the same as those for the LBLOCA described above. (The hot leg e

7 injection flow is assumed to be 500 gpm, but 100 gpm is assumed to flow through

. A1-8 I

, ... . - - . , - + - , . , - -

I 51-5000519-02

)

.the reactor vessel nonle gaps to the dcvneomer). The SBLOCA deboration -

calculation will be started t 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> (360000 seconds) post trip with an initial core f borori concentration of 120000 ppm. This case is chosen to be well out in time with  !

a significant core boron concentration. The case will show that hot leg injection can rapidly arrest core boron concentration buildup and reduce the concentration to >

values well below the solubility limit. Th's case will also assume that the core boiling flow is constant, the sump boron concentration is constant at 3000 ppm, and the deborating equations are the same as those for the LBLOCA.

In equation form the boron mass change is:

DMCB= delta mass core boron,Ibs

CMCB= [Wb

• Csump + Nhil

• Csump - Nhlt

• Ceore)

• Dt/10' -

Where:

Wb = core boiling flow rate, assumed constant Csump = sump boron concentration, ppm boron, assumed constant at 3000 ppm Nhli = Net hot leg injection flow of 400 gpm (500 gpm flow into the hot leg pipe from the decay heat drop line minus assumed 100 gpm leakage through the reactor vessel inlet nonle to the downcomer.

Ccore = Core boron concentration, ppm boron Dt = Time step, seconds 10' = ppm per Ib A1-9

.,, , ._,m'v , . , , . , ,,C,,---. _ , - , , . . - - .,- .,

,-.,..--,,-,,.--..n..-,.y-, , , , . - .. , .,,_y.y - , , , , - , .. . .

, , . . . . y., -

l 51 5000519-02 The initial thermal hydraulic conditions for the SBLOCA case are listed below; I e The reactor is operating at 72 psla/305 F saturated conditions  !

e The initial time is 360000 seconds (100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> post trip)

• Hg at 72 psia is 1181.1 Blu/lb (Reference 7)

• The enthalpy of the hot leg injection water at 140 F is 108 Btu /Lb (Reference 7) l e The density of saturated water at 72 psla is 1/0.017501 ft'/lb (Reference 7) e The core volume is assumed to be 1200 ft'

• The core water inventory is 1200 Ft'/0.017501 ft'/lb = 68568 lb e The initial core boron inventory, MCD=120000 ppm Ta85681b /10' l ppm /m=8228.2 lb e The decay heat fraction at 360000 seconds is 0.00461 (Reference 8). This fraction is the average of the fraction at 350000 seconds (0.00466) and the fraction at 370000 seconds (0.00456): (0.00466 + 0.00456)/2 = 0.00461

. The core decay heat is 0.00461

• 2483299 Btu /sse = 11448 Blu/Sec e 'The core boiling flow is 11448 Blu/sec / (1181.1 Blu/lb - 108 btullb) = 10.7 lb/sec 1

e Although the hot leg injection flow is assumed to mix with the core outlet and upper plenum fluid , no credit is assumed for heat transfer to the hot leg njection fluid.

1 i

By assuming that the boiling flow rate is constant, that the sump boron concentration is conrtant, and that the time step is 500 seconds, the equation for change in core boron mass is:

1 A1-10 9 w~' + " " - - " " ~ * * - e v -

1-- ---r-rv"v' uv -

• 51-5000519 42 DMCB= delta mass core boron,Ibs DMCB= [Wb

• Caump + Nhli

• Csump - Nhli

• Ccore)

• Dt/10' ppm /m reduces to:

DMCB = [10.7 lb/sec

• 3000 ppm +54.7 lb/sec

• 3000 ppm - 54.7

• C core j

• 500 sec/10' pprn'Ib DCMB= [16.05 lb +C2 05 lb 4.02735 lb/ ppm

• Ccore)

DCMB = [98.1 lb - 0.02735

• Ccore)

The deboretion calculations for the SBLOCA follow:

1 Tirne step: 360000 to 360500 seconds DCMB = 98.1 lb - 0.02735 lb/ ppm

• 12n000 ppm = 3183.9 lb CMB, Core boron mass = 8288.2 lb - 3183.9 lb = 5044.3 lb Ccore, core boron concentration = 73566.4 ppm 2* Time step:

DMCB= 98.1-0.027.5 lb/ ppm *73566.4 ppm =1913.9 lb CMB= 5044.3 lb 1913.9 lb=3130.4 lb Ccore = 3130.4 lb/68568 lb

• 10' pprdm =45633 ppm 3* Time step DCMB=98.1 lb .02735 lb/ ppm

• 45653.4 ppm =1150.5 lb MCB= 3130.4 lb-1150.5 lb = 1980.9 lb A1-11

~

51-5000519-02 Ccore = 1980.9 lb / 68568 lb *10' ppm /m = 28869.3 4* Time step DCMB= 98.1 lb - 0.02735 lb/ ppm *28889.3 ppm =691.4 lb MCB = 1980.9 lb - 691.4 Lb = 1289.5 lb Ccore = 1289.5 lb / 68568 lb *10' ppm /m = 18805.8 Followin0 this calculation for 6 more time steps '11 total time steps) produces the data for Table 6 in the main body of this document, in addition to this case, it is assumed that 400 gpm of the 500 gpm hot leg injection flow bypasses the upper plenum. A second case of SBLOCA deboration is evaluated, assuming that the net hot leg injection flow to the upper pienum is only 100 ppm of the 500 ppm injection flow entering the hot leg through the decay heat -

dropline. In this case flow through the reactor vessel nozzle gaps is assured to be 400 gpm. The purpose of this case is to provide further evidence that hot leg injection can control and reduce the bore boron concentration.

As noted above the net hot leg injection flow is assumed to be 100 gpm. This is 100 gpm/7.48/0.01629 Ft'/lb/60 sec/ min =13.7 Lb/sec. This case will use time steps of 1000 seconds. The DCMB equation becomes :

A1-12

_ .. . _ _ ~ _ _ - . . _ . . . _ . . - _ _ _ . - - _ _ _ _ _ _ _ . . . _ . . __ - . . .

i 4 51-2000519-02 DCMB= [Wb *Csump + Nhli

• Csump - Nhil

• Ccore)*1000 sec/10' ppm /m  :

DCMB= 10.7 lb/sec

• 3000 ppm + 13.7 lb/sec

• 3000 ppm - 13.7 lb/sec *

' Ccore)*1000 sec/10' ppm /m DCMB= [32.1 lb + 41.1 lb. 0.0137 lb/pom

• Ccore]

The initial core boron mass is 8228.2 lb, the initial coru concentration is assumeJ to '

be 120000 ppm, and the core volume is . conservatively assumed 1200 fT', and the _

corc water inventory is 1200 Ft' / 0.017501 FT' (Reference 7) = 68568 lb.

Calculation for the first two time steps will be'shown.

1" Time Step DCMB= 73.2 lb-12.7 lb/ ppm *120000 ppm =1570.8 lb MCB = 8228.2 lb - 1570.8 lb =6657.4 lb Ccore = 6657.4 lb /68568 lb *10' ppm /m = 97091.9 d

2 Time Step DCMB= 73.2 lb - 0.0137 lb/ ppm

• 97091.9 ppm =1257.0 lb -

MCB = 6657.4 lb - 1257,0 It v5400.4 lb Ccore = 5400.4 lb /68568 lb *10' ppm /m = 78759.8 Continuing the calculations for 13 more time steps, (15 time steps total) provides the det> oration data for Table 7 in the main body of this document.

I

l. ,

A1-13

51-5000519-02 E

The results of these calculations suggest that hot leg injection provides a rapid

, means of deborating boron build up in the core and outlet plenum.

i k

[ .

E L

e K

E i

A1-14

51-5000519-02 l

APPENDIX 2 REACTOR VESSEL HOT LEG INJECTION FLOW EVALUATIONS

1. INTRODUCTION A sketch of the flow path of the hot leg injection by back flow thrt ugh the decay heat dropline is shown in Figure 11. The decay heat dropline is connected to the bottom of the RCS hot leg pipe at an elevation of 20.14 ft. (00 ft elevation is taken at the upper face of the lower tube sheet of the steam generators). The bottom of the 36 inch ID hot leg pipe is at elevation 19.75 ft. The hot leg injection nozzle is located within the start of the bend of the hot leg 90 ' elbew, about 4.7 inches above the bottom of the hot leg pipe (Reference 3). The inner cylinder of the upoer plenum assembly directly opposite the hot leg nozzle has 24 - 3 inch diameter flow holes in addition to the larger flow holes (6-34 inches ID and 4- 22 Sches ID) located in the plenum cylinder (Reference 3). The area of these small flow holes directly opposite the hot leg nozzles is 1.18 ft' per nozzle (see below). From the n.;l holes opposite the hot leg nozzles, the hot leg injection flows to the upper pienum whers it continues to mix with core outlet steam and water. The saturated, boron rich injection fluid then flows down, by virtue of static head, to the top of the core where it enters the flow holes that direct flow into the region formed between the core barrel and the former plates. There are 24 flow hole's (8 each of 2 inches,3 inches and 4 inches diameter) spaced around the periphery of the upper core plate that provide a flow area of 1.26 ft' for downflow of the injection fluid to the core barrel / baffle region (Reference 5).

Within the core barrel / baffle region there are 8 former plates, each with 80 - 1.312 inch diameter flow holes (Reference 6). These former plate holes make up a flow area of 0.75 ft' From the barrel / baffle region the flow exits to the periphery of the lower core plcte l

A2-1

r- - .

51-5000519-02 l

where there are 64 flow holes ranging in diameter from 1.75 inches to 6 inches (Reference

4) The total flow area for the injection fluid at the lower core plate is 4.30 ft'. From the lower core plate the fluid enters the lower sections of the , eactor vessel and then flows up the downcomer to exit the reactor vessel by way of the affected cold leg. At 500 gpm the l l

dynamic pressure drop through the flow path described above is about 5.4 inches of water (see calculation below). The head to provide this flow is developed by the injection fluid in

^ the hot leg and the entrance to the upper plenum.

The argument to support the hot leg irjection is that the pressure drop in the hot leg injection flow path is small because of the low flow rate (only 500 gpm) and the flow areas, except for the flow area of the reactor vessel internals former plates, are large if the pressure drop in the flow path is relatively small that indicates that a small driving head in the hot leg pipe or the upper plenum will support the hot leg injection flow path.

The fluid in the reactor vessel is assumed to be saturated at 14.7 psia or the RCS pressures of the SBLOCAs. (The incoming injection fluid from the LPI or HPl is heated to saturation by the vent valve steam flow. The boiling tiow rates through the downcomer, the core and the upper plenum are low because of the relatively low flow core boiling flow rates and the large flow areas. The driving head for the boiling flow is the gravity head formed by the density difference between the boiling in the upper core and the saturated water downcomer.)

A2-2

7 51-5000519-02 The water density in the hot leg injection flow path is expected to be saturated water throughout the flow path.

2. CALCULATION OF HOT LEG IN,lECTION FLOW PATH PRESSURE LOSSES Calculailon of the pressure losses through the several plate flow holes in the hot leg injection flow path is performed below.

2.1 Identification of Flow Holes a) Plenum Cylinder Flow Holes (Referece 3)

There are 24- 3 inch flow holes in the plenum cylinder adjacent to the hot leg nozzle. These holes are arranged in rows as follows:

Row Number of flow holes 1 2 2 2 3 4 4 2 5 4 6 2 7 4 8 2 9 .2 24 The flow area of these holes is:

2 2 24*0.785*(3.0 in)'/144 in'/ft =1.1775 ft'. Use 1.18 fi .

b) Upper Core Plate Flow Holes (Reference 5 )

There are 24 flow holes in the upper core plate. Their numbers and dimensions are:

2 8-3 inch dia holes: 8*0.785*(3.0 in)'/144 in'/Ft = 0.392 ft' 8-2 inch dia holes: 8*0.785*(2.0 h)2/144 in'/Ft'= 0.174 ft' 2

84 inch dia holes: 8*0.785*(4.0 in)2/144 in'/Ft = 0.70 ft2 1.266 ft' I

A2-3

51-5000519-02 c) Former Plate Flow Holes (Reference 6)

The former plates have 80-1,312 in dia flow holes.

The flow area por former plate is:

2 80*.785*(1.312 in)'/144 in /ft'=0.75 ft' d) Lower Core Plate flow holes:(Reference 4)

There are:

8-3 in dia holes S*.785*(3 in)'/144 in'/ft* = 0.392 ft' 8-2.5 in dia holes S*.785*(2.5 in)'/144 in'/ft'= 0.273 ft' 8-2.0 in dia holes S*.785*(2.0 in)'/144 in'/ft'= 0.174 ft' 84.0 in dia holes S*.785*(6.0 in)'/144 in'/ft'= 1.57 ft' 8-3.5 in dia holes S*.785*(3.5 in)'/144 in'/ft'= 0.534 ft' 161.75 in dia holes-16*.785*(1.75 in)'/144 in'/ft'= 0.267 ft' 8-5,0 in dia holes--8*.785*(5.0 in)'/144 in'/ft'= 1.090 ft' 2

Total 1.30 ft e) Summary of Flow hole areas in the hot leg injection flow path Plenum cylinder adjacent to hot leg nozzle 1.18 ft' Upper core plate inlet to core barrel / baffle area 1.26 ft' Former Plate 0.75 ft' 2

Outlet holes in lower co're plate d.30 ft 2.2 Calculation of Velocities in the Flow Holes velocity = flow / area / density Flow = 500 gpm Density of water at 140 F=1/0.01629 ft'/lb=61.39 lbKt' Mass flow =500 g/miT61.4 lb/ft'/7.48 gal /ft'/60 sec/ min =68.4 lb/sec a) velocity in plenum cylinder flow holes =

A2-4

. . _ _ _. . . __ - _ ~ _ _ . . _

51-5000519 02 1

' 68.4 lb/sec/1.18 ft2/61.4 lbM'=0.944 ft/see b) - velocity in upper _ core plate flow holes =

68.4 lb/sec/1.26 ft2/61.4 lbM'=0.88 ft/sec c) velocityin former plate flow holes; 68.4 lb/sec/0.75 ft2/61.4 lb/ft'=1.49 ft/sec -

d) velocity in lower core plate flow holes; ,

68.4 lb/sec/4.30 ft2/61.4 lbm8=0.26 ft/sec

- 2.3 Calculation of pressure drops in the several flow holes:

delta p= DP = k* rho'v'/144/2g:

k = is assumed to be 1.5 velocity heads entrance (k=0.5) and exit loss (k=1.0) at esch plate (Total loss factor =0,5 +1.0 velocity heads) rho is water density = taken as 61.4 lb/ft' as above. This value of density is used for conservatism (higher DP) of the pressure losses in hot leg injection flow path.

g= gravitational constant =32.2 ft/sec/sec a) DP plenurn cylinder flow holes =

2 1.5'61.4 lb/ft**(0.944 ft/sec)'/(144 in /ft2*2*32.2 ft/sec')=0.00885 psi b) DP upper core plate:

1.5*61.4 lb/ft(0.88 ft/sec)'/(144 in'/ft'*2*32.2 ft/sec')=0.00769 psi c) DP former plates:

8 plates *1.5T1.4 lb/ft'*(1.49 ft/sec)'/(144 in'/ft'*2*32.2 ft/sec')=0.176 psi d) DP lower core plate:

1.541.4 lb/ft'*(.026 ft/sec)2 /(144 in'/ft 2.2*32.2 ft/sec )=0.0000067_

2 psi

- A2-5

51-5000519-02 e) Sum of DPs =(0.00885+0.00769+0.176+0.00067)=0.193 psi Convert DP in psi to inches of water one psi =lblin'*144 in'/ft'/61.4 lb/ft'=2.345 ft or 1/2.345=.4264 psi /ft then 0.193 psl/0.4264 psi /ft = a water column 0.453 ft or 5.4 inches high.

This is a small head required to drive the hot leg injection flow through the flow path described above. This head can be easily created in the reactor vessel upper plenum by the hot leg injection.

3.0 REFERENCES

The references list for this Appendix is the same as that identified in Section 9 of the text.

l 1

A2-6

I 51-5000519 b2 APPENDIX 3 EVALUATION OF BORONOMETER AND INCORE TEMPERATURE BORON MEASUREMENT UNCERTAINTIES

1. INTRODUCTION This appendix presents the uncertainty evaluation of the boronometer measurement uncertainties and incore temperature measurement uncertainties that can be used to determine if boron is concentrating in the core post LOCA and if active boron dilution methods are required. Five LOCA cases are evaluated for the measurement uncertainties. The cases from Section 4 are:

Volume Case 1 Case 2 Case 3 Case 4 Case 5 GWST 3000 ppm 2270 ppm 3000 ppm 2270 ppm 2270 ppm CFT 3500 ppm 2270 ppm 3500 ppm 2270 ppm 2270 ppm RCS 3000 ppm 2270 ppm 0000 ppm 0000 ppm 0000 ppm, The BWST volume assumed for cases 1-4 is 350,000 gallons. The BWST volume for case 5 is assumed to be 250,000 gal ons.

2. Discussion Approach The total boron measurement uncertainty is to be determined as the square root of the sum of the squares of; 1) the boron measurement uncertainty, and,2) the incore temperature measurement uncertainty as defined in References 13 and 14 respectively. This " square root of the sum of the squares " approach is reasonable because these measurements (boronometer and incore temperature) are independent of each other.

The uncertainty in the boron measurement is taken directly from Attachment 1 of A3-1

I 51-5000519-02 q reference 13., included here as Figure A3-1. The boron measurement uncertainty, Figure A3-1, is a plot of the boronometer measurement uncertainty (+/- ppm) as a function of the actual boron concentration in ppm. Over the boron concentration range of interest (up to about 3000 ppm), the boronometer uncertainty ranges from, about +/- 65 ppm at 1000 ppm to about +/-185 ppm at 3000 ppm boron concentration.

The boron measurement uncertainty is fitted to a straight line approximation in the range frem 1000 ppm to 6000 ppm boron. The equation for this straight line approximation is derived below.

Below 1000 ppm boron, the barm measurement uncertainty is assumed to be

+/- 65 ppm. This allows a ready determination of the error as a function of the assumed sump concentration.

From reference 14, the incore temperature measurement uncertainty in the temperature range of interest (212 'F to 305 'F ) is + 33.25 'F or - 43.5 'F. The boron and temperature measurement uncertainties will shift the " Delta Function" curves to the right resulting in less margin for acceptable operation.

The boron concentration worth (ppm boron) of incore temperature uncertainty is developed by shifting the concentration difference (in ppm) at RCS saturation temperature by plus 43.5 'F at given RCS saturation temperature points. A curve of the " Delta" concentration difference (i.e., average boron to sump difference) for the incore temperature uncertainty versus RCS Saturation Temperature is developed for each of the five cases defined above.

Figure A3-2 illustrates this procecs. The incore temperature uncertainty in ppm boron is the difference between the Delta function curve and the incore temperature uncertainty curve derived above. The measurement uncertainty is then determined at several temperature points. The total boron uncertainty is determined by taking the square root of the sum of the squares (SRSS) of the boronometer measurement uncertainty and the incore temperature uncertainty.

A3-2

l

[

i 51-5000519-02 in addition to the SRSS determination of the boron measurement uncertainties, methods, FTl also performed a " Monte Carlo' measurement uncertainty evaluation for case 1. The results of the Monte Carlo uncertainty evaluation closely match the SRSS method discussed above. The results of the boron measurements and incore temperature measurement uncertainty evaluation are shown on Figures 4A, 48,5A,58, and SC as the SRSS uncertainty.

3. Calculations Boron Measurement Uncertainty The equation of the boronometer measurement uncertainty (Figure A3-1) is developed as follows:

UB= A + m x CB, where, UB = boron measurement uncertainty, ppm boron A= constant = (Y axis intercept) m = slope of the line, ppm boron uncertainty / ppm boron CB = boron concentration From Figure A3-1 at 6000 ppm the boron measurement uncertainty is 372 ppm at 1000 ppm the boron measurement uncertainty is 68 ppm thus,372 ppm = A + m x 6000 pprp, and 68 ppm = A + m x 1000 ppm, subtracting, 304 ppm = 5000 ppm *m m = 304 ppnV5000 ppm = 0.0608 ppm / ppm and A= 372 ppm - 0.0608

• 6000 ppm = 372 ppm -364.8 ppm = 7.2 ppm and, UB= 7.2 ppm + 0.0608 ppm / ppm

• CB A3-3

..--.r

51c5000519-02 ~

Incore Temperature Measurement Uncertainty .

The boron worth of the incore temperature measurement is determined as shown ,

below:

At several RCS saturation temperature points, such as 180 F,200 F,220 F, and 240 -

F the boron concentration difference (ppm) is moved to the right by

~

43.5 *F The table below illustrates the development of boron worth for the incore - -

temperature measurement uncertainty for Case -1: t RCS Saturation Ave Boron to Sump RCS Saturation - Ave Boron to Sump .

Temp, *F Diff, ppm . Temp + 43.5 F Diff, ppm 180- 409 223.5 409 200 550- 243.5 550 212 644 255.5 644 220 695 263.5 695 240- 872 283.5 872 -

260- . 1135 303.5 1135

-280 1456 323.5 1456

" The data in columns 3 and 4 are plotted as the incore temperature measurement uncertainty. on the same plot as columns 1 and 2 and subtracted to obtain the boron uncertainty at given temperature points. This yields the following; RCS Saturation Temperature,' 'F ,

. Boron Worth ofincore Temperature -

measurement Uncertainty, ppm -

_'212' 294-220' -295:

240 332 2601 455 t280 596

~

g gg +y--* g e-y= . p- - - = - w---hq- g* -- Mer r- g V>-se i

51-5000519-02 The measurement uncertainty of the boronometer measurements are calculated from: UB=7.2 ppm _+ 0.0608 ppm / ppm

• CB and are:

RCS Saturation DC & Sump Boronometer Uncertainty,-

Temperature, F Concentration, ppm ppm

212- 2375- 151.6 220' 2324 148.5 240 2147- 137.7-260 1884 121.7 280- 1563 102.2 The SRSS unceitainty for the boron and Incore measurement uncertainties are:

RCS Ave Boron SRSS Calculation SRSS Indicated Saturation to Sump Measurement SRSS Ave Temperature, Diff, ppm Uncertainty, Boron to F ppm Sump Diff, ppm 212- 644 2 2 (151.6 + 294 as = 330.8 313.2 220 695 (148.5' + 295 2

"' = 330.3 364.7 240 872 (137.7' + 332 as = 359,4 2

512.6 260 1135 (121.7' + 455' = 471.0 664 280 1456 (102.2' + 596 2

= 604.7 851.3 This same procedure is followed for cases 2-5 to determine the indicated SRSS Ave Boron to sump Diff.

6 A3-5 4

y,-m e-m8- -

9 w-e r- m p -

51-5000519-02 Case 2: Refer to Figure A3-3 : Case 2 : Delta Difference and incore Temperature versus RCS Saturation Temperature.

ROS 212 220 240 260 280 Saturation Temp.

• F Ave Boron S54 705 882 1145 1466 to Sump Diff, ppm RCS 255.5 263.54 283.5 303.5 323.5 Saturation Temp +

43.5 'F lncore 298 300 330 450 616 Temp.

Meas.

Uncertainty Boron Worth , ppm DC & Sump 1616 1565 1388 3125 804 Conc., ppm Boronmeter 105.5 102.4 91.6 75.6 68 Uncertainty, ppm 2 2 SRSS (105.5'+ (102.4 + (91.6'4 (75.6 + (68'+

2 2 2 2 Calculation 298 )'5 300')'5 330 )5 450 )5 616)s SRSS Total 316.1 317 342.5 456.3 619.7 Uncertainty, ppm Indicated 654-316.2 705- 882-342.5= 1145-456.3= 1466-Delta =337.9 317.0=388 539.5 688.7 619.7 Function, =846.3 ppm A34

51-5000519-02 Case 3: Refer to Figure A3-4: Case 3: Delta Difference and Incore Temperature versus RCS Saturation Temperature.

RCS- 200 220 240 260- 280 Saturation Temp.

• F Ave Boron -556 700 877 1140 1461 to Sump Diff, ppm RCS 243.5- 263.5 283.5 303.5 '323.5 Saturation '

Temp +

43.5 'F Incore 296 300 337 460 611 Temp.

Meas.

Uncertainty Boron Worth , ppm JC & Sump 2057 1913 1736 1472 1152 Conc., ppm Boronmeter 132.2 123.5 112.7 96,7 77.2 Uncerta!nty, ppm 2

SRSS (132.2'+ (123.5 +

2 (112.7 + (96.7 +

2 (77.22 ,

2 2 2 Uncertainty 296')* 300')" 337 )" 460)3 611)s Calculation -

SRSS Total 324.2 324.4- 355.3 470.0 615.9 Uncer'ainty, Ppm Indicated - 556-324.2= 700-324.4= 877-355.3= 1140470= 1461-Delta 231.8 375.6 521.7 670 615.9=

. Function, 845.1 ppm A3-7

5000519-02 ~

i:

h t

, Case di Refer to Figure A3-5: Case 4 Delta Difference and incore Temperature -

' versus RCS Saturation Temperature.

RCS :200' 220 240 260 280 Saturation Temp. ' F

' Ave Boron 565 709 886 1140 1470 to Sump Diff, ppm RCS 243.5 263.5 283.5 303.5 323.5 Saturation -

. Temp + '

43.5 *F Incore- 290 299 341 449 584 l

Temp.

Meas.

Uncertainty Boron DC & Sump 1398 1254- 1077 814 493 Conc., ppm Boronm5ter 92.2 83.4 72.7 68 68 Uncertainty, Ppm 2

SRSS- (92.2'+ (83.4'+ (72.7'+ (68 + (68'+

2 2 2

' Calculation 290')* 299 )5 341')* 449)s 584)4-

' SRSS Total 304.3 310.4- 348.7 454.1 587.9

. Uncertainty, ppm-Indicated ~ 565 -304.3= 709 -310.4= 886 -348.7= 1149- 1470-Deltc 260.7 - 398.6- 537.3 /,54.1 = 587.9=

Function, - 694.9 882.1

ppm-A3-8

__ ,_ ~ _ . . _ - _ - .,

5000519-021 1

RCS 200 220. 240'- 260. .280-

. Saturation  !

- Temp. F t

~ Ave Boron :744- 934 1166. 1513 .1868' to Sump '

Diff, ppm

RCS 243.5 ~ 263.5 < -283.5 303.5 - 323.5

. Saturation Temp +

43.5 'F '

incore .

369 389 '446 613-Temp.

- Meas.

, Uncertainty l

Boron Worth , ppm DC & Sump - 1123 - ~934 701 355 0

. Conc., ppm Boronmeter 75.5 68 . 68 68 Uncertainty, p.om 2

SRSS- (75.5+ ' (68'+ (68'+ (68'+

L Calculation 369')' 389')' - 446')* 613')*

' SRSS Total 376.6 394.9 451.2 616.8 Uncertainty, ppm. -

Indicated 744-376.6= : -934-394.9= 1166- -1513-

- Delta 367.4 . 539.1 ~ 451.2= . 616.a=

Functione ' 714.8 -896.2 ppm.

t-l L

r.. - -

I' I_

i L - A3-9 l l

51-5000519-02 ihe indicated ' Delta Function' data as developed above is' plotted on Figures

4A through 50. .

4. REFERENCES

- The references for this Appendix are included in the Reference Section (9) of the main body of this report.'

j l -

)

e l r

~

A3-10

('

y

._. ~ . , . - .--2._ . _ . _ . _ _ _ . _ _ . . . _ , . .

FIGURE A3-1 51-500051h-02 Machmt.11 Nof: 971828 BORONOMETER MEASUREMENT UNCERTAINW P'8' 1 # I VERSUS ACTUAL BORON CONCENTRATION, PPM (REFERENCE 13)

,I

\  :

N -

g N' .

x .

I

\ ,

= .

I

s .

8g i

d xN '

i 3

I g.

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