ML20211H308

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Rev 3 to Allowable Leakrate Calculation for SG Interim Plugging Criteria
ML20211H308
Person / Time
Site: Byron, Braidwood  Constellation icon.png
Issue date: 09/30/1997
From: Launi C
COMMONWEALTH EDISON CO.
To:
Shared Package
ML20211H271 List:
References
BRW-97-0798-M, BRW-97-0798-M-R03, BRW-97-798-M, BRW-97-798-M-R3, NUDOCS 9710060320
Download: ML20211H308 (26)
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l l

l l Attachment C Braidwood OMSite Dose Calculation 1

9710060320 971001 4 ADOCK 0500 gDR L:nla bybwd umgen & mal 2 6

l PREPARATION, REVIEW AND APPROVAL OF CALCULATIONS CALCULATION TITLE PAGE Calculation No: BRW 97-0798.hi l DESCRIPTION CODE:_B9f I DISCIPLINE CODE: hi IIRAIDWOOD STATION UNITS 1&2 SYSTEM CODE: RC. hts TITI,E: Allowable Leakrate Calculation for Steam Generator Interim Plugging Criteria l

__ X Safety Related __ Augmented Quality .._

_ Non Safety Related REFERENCE NUMDERS Type Number Type Number COMPONENT EPN: DOCUMENT NUMHERS:

EPN Compt Type Doc Type / Subtype Document Number REMARKS:

REY. REVISING APPROVED DATE O.

ORGANIZATION PRINT / SIGN 0 S&L C, hi. Launi/(See original for signature) 8/29/97 1 S&L C. hl. Launi/(See original for signature) 9/3/97 2 S&L C. hi. Launi/(See original (or signature) 9/22/97 3 SeL- 0,M. Lhat/f./N&,y Hog

/

c

l I

COMMONWEALTII EDISON COMPANY CALCULATION REVISION PAGE CALCULATION NO 11RW.97-0798 M PAGE NO.: 2 REVISION SUMMARIES REV: 0 IGVISION

SUMMARY

Originalissue, pages 123 Electronic Calculation Data Files:

(Propam Name, Ymion, file name eWilm'datehour/: min)

None Prepared by: W J. Johnson /(See original for signaturc)_. 8/29/97 Print / Sign Date Reviewed by:.R. G. Chow /(See original for signature) 8/29/97 Print / Sign Date Type of Review

[ X ] Detailed [ ] Alternate [ ] Test DO ANY ASSatiqlONS IN1111S CAlfULA110N RIVJ!RE LAllRVE RIFICA110N [ ]iTS [X]NO Tracked by:

REV:1 REVISION

SUMMARY

Corrected typographical error on page 24.

Electronic Calculation Data Files:

(Propam Name, Version. File name etsindatehourl: min)

None Prepared by: W. J. Johnson /(See original for signaturet_ 9/3/97 Print / Sign Date Reviewed by: R. G. Chow /(See original for signature) 9/3/97 Print / Sign Date Type of Review

[ X ] Detailed [] Alternate [ ] Test DO ANY ASSatI910NS IN 1111S CAlfULAT10N REQUIRE IATER VERIFICATION [ ] YES [ X] NO Tracked by:

COhlh10NWEALTil EDISON COh1PANY CALCULATION REVISION PAGE CALCULATION NO. BRW.97-0798-hi PAGE NO.: 2.1 REVISION SUhth1 ARIES REY: 2 REVISION SUhihiARY:

Corrected secondary side activities based on new information from Westinghouse. Also corrected typographical errors on page 12 and 23.

Electronic Calculation Data Files:

(Propam Name, Version, File name en'alts/datshourh rnin)

None Prepared by: 3V. J. Johnson /(See original for signature) 9/22/97 Print / Sign Date Reviewed by: R. G. Chow /(See original for signature) 9/22/97 Print / Sign Date Type of Review

[ X ] Detailed [ ] Alternate [ ] Test DO ANY ASSUMITIl0NS IN 1111S CALLULA110N REQUIRE IATIR VIRIDCA110N [ ] YES (X]NO Tracted by:

REV: 3 REVISION SUhthtARY:

Added secondary side releases to LPZ 0-2 hr dose. Clarified references, design inputs, and text.

This revision completely supersedes all previous revisions.

f Electronic Calculation Data Files:

(Iwyam Name, Version, File nanw en'aize/datshourh min)

None Prepared by: W. J Johnson / - 'D/ W/o 7

~

Reviewed by: R. G. Chow V g

'Prin't/ Sign '

Date Type of Review

[ X ] Detailed [ ] Alternate [ ] Test DO ANY ASSUMI910NS IN1111S CAlfU1All0N REQUIRE IATIR VERIHCA110N [ ] YES [ X ] NO Tracked by:

I

COMMONWEALTil EDISON COMPANY CALCULATION TABLE OF CONTENTS CALCULATION NO. BRW 97-0798 M REV.NG.3 PAGE NO. 3 SECTION PAGE NO. SUB PAGE NO.

111LE PAGE I REVISION

SUMMARY

2 2.1 l TABLE OF CONTENTS 3 l

PURPOSE /0BJECTIVE 4 METilODOLOGY AND ACCEPTANCE CRITERIA 4 ASSUMPTIONS 5 DESIGN INPUT 5 REFERENCES 6 CALCULATIONS 7

SUMMARY

AND CONCLUSIONS 24 ATTACliMENTS N/A

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW.97 0798.M PROJECT NO. PAGE NO. 4 l PURPOSE AND OBJECTIVE:

The purpose of this calculation is to generate the maximum allowable primary to secondary steam generator tube leak rate during a postulated main steam lird break using 24% plugging criteria design date. The evaluation was performed for both a pre accident and accident initiated lodine spike. The release of lodine and the resulting thyroid dose at the Exclusion Area Boundary and Low Population Zone were considered in the leak rate determination. Whole body dose due to noble gas immersion is less limiting than thyroid dose as documented in UFSAR Table 15.011. Given the large margin to the 25 rem whole body dose limit, whole body dose was not re evaluated.

This calculation also determine the resulting thyroid dose at the Exclusion Area Boundary and Low Population Zone for the actual predicted end of cycle 7 steam generator tube leakage during a postulated Main Steam Line Break METHODOLOGY AND ACCEPTANCE CRITERIA:

The Main Steam Line Break (MSLB) accident is evaluated because the event causes a sustained large pressure difference across the steam generator tubes providing a motive force for reactor coolant system (RCS) release.

The dose attributed to a 1 gpm leak rate from the reactor coolant system was calculated. This value was then used to determine the allowable leak rate without exceeding the Standard Review Plan dose criteria.

The cctivity released to tue environment due to a MSLB is analyzed in two distinct releases:

1. The release of the iodine activity that has been established in the secondary coolant prior to the accident, and
2. The release of the primary coolant iodine activity due to tube leakage.

The methodology used for calculating the Radiological Consequences of a MSLB with primary to secondary leakage is consistent with the Standard Review Plan (NUREG 0800),15.1.5 Appendix A.

TID 14844 dose conversion factors were used to determine dose equivalent lodine concentrations for the RCS, which is the Technical Specification definition of dose equivalent lodine. The TlO values are based on ICRP 2,

' Permissible Dose for intemal Radiation,1959.*

The off site dose assessment uses ICRP 30,

  • Limits for intakes of Radionuc!! des by Workers,1979' rbse conversion factors. ICRP 30 is also the basis for Federal Guidance Report No.11, ' Limiting Values oi Radionuclide intake and Air Concentration and Dose Conversion Factors for Inhalation, Submersion, and Ingestion,' dated 1988.

The dose Acceptance Criteita are based on the guidance of Standard Review Plan (NUREG 0800) Section 15.1.5, Appendix A. For a MSLB with a postulated pre-accident lodine spike, the calculated doses should not exceed the guideline values of 10CFR Part 100 Section 11. The numerical values used for these doses are 25 rem to the whole body and 300 rem to the thyroid from lodine exposure for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> following the accident. For a MSLB with an accident inttlated lodine spike, the calculated doses should not exceed a small fraction of the 10 CFR 100 guideline values, i.e,2.5 rem and 30 rem respectively for the whole body and thyroid doses.

l REVISION NO.: 3 I

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 974798 M PROJECT NO. PAGE NO. E l ASSUMPTIONS:

1) The effect of boron on the RCS density is assumed to be negligible since the boron mass is less than 1%

of the total RCS mass at the beginning of core life.

DESIGN INPUTS: l

1. The total volume of the RCS is 12.062 ft', (Ref.1)
2. The full power RCS temperature and pressure are 586.2 *F and 2250 pala. (Ref.1 cnd 2)
3. The RCS specific volume at full power is 0.02258 ft'/lbm. (Ref 3)
4. (Deleted)
5. Letdown Purification System temperature and pressure are 130 *F and 2300 psig. (Ref.1).
6. Letdown Purification System specific volume is 0.01613 ft'/lbm. (Ref. 3)
7. Breathing rates are taken from UFSAR Table 15A 1 (Ref 6)
8. Atmospheric Dilution Factors, X/Q, are the fifth percentile values taken from UFSAR Table 15.014.

(Ref. 7)

9. RCS lodine concentrations are based on UFCAR Table 11.12. (Ref. 8)
10. The initial steam release from the defective and intact steam generators are taken from UFSAR Table 15.1 3. (Ref. 9)
11. The secondary side faulted steam generator has a partition coefficient of 1.0 and the intact steam generators have partition coefficient of 0.1 (Reference 15)
12. The half life for 1131 is 8.04 days,1132 is 2.30 hrs,1133 is 20.8 hrs,1134 is 52.6 min, and 1135 is 6.61 hrs (4 = 0.693/ half life). (Ref. 21)
13. The initial primary coolant activity for the pre accident spike is 60 pCl/g DE l 131 and 1 Cl/g for the accident initiated spike (Ref,12 and 14)
14. The Inillal secondary coolant activity is 0.1 Cl/g DE l 131, (Ref.12 and 14)
15. The duration of the spike is 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. (Ref. 24)
16. No fuel failure attributable to the accident since DNB design basis is met. (Ref.12 and 25)
17. lodine partition coefficients for all SGs are 1.0 for primary to secondary leakage. (Ref.15)
18. Normal letdown purification flow is 75 gpm. (Ref 1)
19. (Deleted) l REVISION NO.: 3 l

.. ..____ ___~_ _. _ _ _ _ - _ _ _ _ . . . _ _ . . _ _ . . _ . _ _ _ _ _ . . _ _ _ .

COMMONWEALTH EDISON COMPANY ,

l CALCULATION NO. BRW 97 0798 M PROJECT NO. PAGE NO. 6 l i

20. (Deleted)
21. Domineralizer Decon Factor, DF, for lodine is 10. (Ref 1)
22. The lodine release rate spike factor Is 500. (Ref 12)
23. Allowable primary to secondary leak rate is 150 gallons per day (0.1 gpm) per steam generator. (Ref.14)
24. Dose conversion factors are based on ICRP 30 values using the significant digits from Federal Guidance Report No.11. (Ref.17 and 20)
25. Projected end of cycle 7 IPC leak rate is 57.1 and circumferentialleak rate is 5 gpm based on room temperature and pressure. (Ref. 5) i REFERENCES
1) B/B UFSAR Table 11.1 1, Revision 0, as amended in Reference 22
2) B/B UFSAR Table 5.1 1, Revision 0
3) ASME Steam Table, Fifth Edition
4) (Deleted) i
5) BRW DIT 97 278, inputs into Offsite Dose Calculation to Support Unit 1 Reduced RCS DE I.131 Activity Limit, Rev.1
6) B/B UFSAR Table 15A 1, Revision 0
7) B/B UN AR Table 15.014 Revision 0
8) B/B UFSAR Tab!e 11.12, Revision 0
9) B/B UFSAR Table 15.13, Revision 6
10) Introductory Nuclear Physics by Kenneth S. Krane,1988
11) (Deleted)
12) Standard Review Plan (NUREG 800),15.1.5 Appendix A
13) (Deleted)
14) Technical Specifications 3.4.8 (Amendment 69),3.7.1.4 (Original), 3.4.6.2 (Amendment 57)
15) WCAP 14046,'Braldwood 1 Technical Support for Cycle 5 Steam Generator Interim Plugging Criteria?

dated May,1994, I REVISION NO.: 3 l

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 97 0798 M PROJECT NO. PAGE NO. 7 l

16) ICRP Publication 2, Report of Commit'ee il on Permissible Dose for Intemal Rau. tlon,1959
17) ICRP Publication 30, Limits for intakes of Radionuclides by Workers,1979
18) J. P. Adams and C. L. Atwood,'The lodine Spike Release Rate During a Steam Generator Tube Rupture,' Nuclear Technoloav, Vol. 94, pp 361371 June,1991 and EGG NERD-8648 Technical Report

' Probability of the lodine Spike Relesse during an SGTR,' September.1989

19) Westinghouse Letter CAE 97171, dated July 21,1997, pertaining to the Reactor Coolant Water Density used in Determining Byron and Braidwood Altemate Tube Plugging Limit.
20) Federal Guidance Report No.11,'Li niting Values of Radionuc!!de intake and Air Concentration and Dose Conversion Factors For Inhallition, Submersion, and Ingestion,1988
21) NUREG/CR 1413,'A Radionuclide Decay Data Base -Index and Summary Table,' 1980
22) ' Primary Coolant Source Terms,' Westinghouse letter CAE 97185, CCE 97 225, dated September 19, 1997
23) TID 14844,' Calculation of Distance Factors for Power and Test Recctor Sites,' March 23,1962
24) B/B UFSAR Section 15.1.5.3, Revision 6
25) B/B UFSAR Section 15.1.5.1, Revision 4 VARIABLE AND CONSTANT DEFINITIONS:

M RCS mass [g]

Mem Steam Generefor $

steam release mass [lb)

V RCS volume [ft )

v A RCS specific volume [ft'/lbm))

RCS leak rate constant [sec' 4,e Fuel Release constant [Cl/sec) 4 Isotope Decay Constant [sec")

d ko Letdown Purification Removal Constant [see )

4 Total lodine Removal Rate [sec")

t Time [sec)

A. RCS lodine activity [Cl)

C, lodine Concentration [Cl/g or CL/01 C, Inltiallodine Concentration [Cl/0 or Cllg)

I', Letdown Purification Flow [g/sec)

R. Activity Released of nuclide,i[Cl)

D Thyroid Inhalation Dose [ rem]

r4 Breathing Rate [m*/sec) 3 X/Q Atmospheric Dilution Factor [sec/m )

W. DCF Weighted Activity [ rem]

DE I 1.'1 Dose Equivalent 1131 l REVISION NO : 3 l

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 97 0798 M PROJECT NO. PAGE NO. 8 l DEFINE UNITS:

Cl = 1 Curie pCl = 1E 6 Cl 11bm = 454 g i ft' = 7.46 gal 1 min = 60 sec 1 Sv/Bq = 3.7E12 rem /Cl

1. CALCULATION OF DO8E CUE TO STEADY STATE ACTIVITY IN SECONDARY 8IDE The first dose component to be calculated will be the dose from the se?ondary side. The secondary side activity is conservatively taken as the Technical Specification limit of 0.1 Cl/g (Design input 14). This value is the same for both the pre-accident and accident initiated events. The steam release for the faulted steam generator (SG) Is 96.000 lbs (Design input 10) which is the entire initial SG water mass.

The faulted SG is assumed to steam dry in 1015 minutes so all of the lodine is available for release.

The combined 0-2 hr steam release for the three intact steam generators is 406,716 lbs (Design input 10). The combined 2 8 hr steam release for the three intact SGs is 939,604 lbs (Design input 10). For the three intact SGs a partition coefficient of 0.1 is used (Design input 11).

a. The lodine concentrations are obtained from UFSAR Table 15.0-9 as updated in Reference 22 and are converted to Cl/lb, since the steam release is defined in Ibs.

C = C, x 454 x 1E - 6 Equation 1.a TABLE 1.a

Nuclide ' lodine Concentration, C., lodine Concentration, Ci, (UF8AR Table 16.0 9, Ref 22)  ?(Equation 1.a)-

[gCl/el:

[Cl/lb) ?

l131 0.0645 2.93E 5 l132 0.0723 3.26E 5 l133 0.1032 4.69E 5 l134 0.0155 7.04E-6 l135 0.0567 2.57E 5

. I REVISION NO.: 3 l

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 97 0798 M PROJECT NO. PAGE NO. 9 l

b. The lodine concentration for each nuclide, C, from Table 1.a Is multiplied by the mass of steam released (96,000 lbs for the faulted SG and 406,716 lbs for the three intact SGs) and then multiplied by the partition coefficient (1.0 for the faulted SG and 0.1 for the intact SGs) to obtain the curies released, R., for 0-2 hours.

Rl"d(Ci]= C, x M'"d (Ib)x 1.0 Equation 1.b.1

. lb.

Rl"(Ci]= C, x Mb"(Ib]x0.1 Equation 1.b.2

. lb.

TABLE 1.b Nuclide - Activity Released from Activity Released from Faulted SG, Ri" " . = intact SGs (0 2 hrs), R",

(Equation 1.b.1) [Cl) (Equation 1.b.2) [Cl]

l131 2.81E0 1.19E0 1132 3.15E0 1.33E0 1133 4.50E0 1.91 E0 1134 6.76E 1 2.66E 1 1135 2.47E0 1.05E0

c. The activity released, R. determined above,is multiplied by the ICRP 30 Dose Conversion Factor, DCF., (Design input 24) for each lodine isotope and then summed separately for the faulted SG and intact SGs. The DCF weighted activity released is:

I'*

W["d(rem]= R["d(Ci]x DCF, Equation 1.c.1

. Ci .

W,'"(rem]= Rl"(Ci]x DCF, 1*- Equation 1.c.2

. Ci .

l REVISION NO.: 3 l

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

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 97 0798 M PROJECT NO. PAGE NO.10 l TABLE 1.c Nuclide ICRP 30 Dose Weighted Activity Wolghted Activity conversion Factor, from Faulttd 80, from Intact sos, DCFi, (Design input W' *", . W'",(0 2 hrs)

24) [ rom /Cl] (Equation 1.c.1) [ rem] (Equation 1.c.2) [ rem]

l.131 1.08E6 3.03E6 1.29E6 1132 6.44E3 2.03E4 8.57E3 1133 1.80E5 8.10E5 3.44E5 l134 1.07E3 7.23E2 3.06E2 1135 3.13E4 7.73E4 3.29E4 TotalI(Re xDCFi) 3.94E6 1.68E6 The 0 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> weighted activity released from the faulted and the three intact SGs is 5.62E6 rem (3.94E6 + 1.68E6 rem). This total weighted activity can also be defined as I,(R,xDCF).

The DE l 131 activity released from the faulted and intact seam generators is the total weighted activity from Table 1.c divided by the 1131 dose conversion factor. Numerically this is 5.20 Cl DE l 131 '5.62E6 rem /1.08E6 rem /CI)

d. The off site thyroid Inhalation dose at the exclusion area boundary, Dr.Aa, is calculated in accordance with UFSAR equation 15A 2. The LPZ doses for both the pre accident and accident initiated lodine spike cases include the activity released from the secondary side and are calculated in steps 2.f and 3.f. respectively. The breathing rate is based on the 0-8 hour time period.

Exclusion Area Boundary Dose (0-2 hours) for Secondary Side Release r 3 Dm(rem]= L xBx (R, x DCE) Equation 1.d.1 (Qsm 3-

= 7.7E- 4 x3,47E-4 *-- x 5.62E6[ rem)

$m , ,sec,

= 1.50 (rem) l REVISION NO.: 3 -]

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW.97 0798 M PROJECT NO. PAGE NO.11 l

2. GALcVLATION OF DOSE DUE TO PRIMARY TO4ECONDARY LEAKAGE DURING PRE.

ACCIDENT INITIATED 8PlKE '

In accordance with Reference 12, the pre accident case occurs when the reactor is operating at the

, maximum value permitted by the Technical Specifications prior to the postulated MSLB. The radioactive isotopes are assumed to be evenly distributed throughout the RCS. The lodine activity changes over time due to radioactive decay and the rate at which activity leaves the RCS due to primary to secondary tube leakage.

2

a. The RCS mass inventory, M, will be calculated given the hot full power volume and specific volume.

RCS Volume: V=12062 ft' (Design input 1) ,

RCS specific volume v=0.02258 ft'/lbm (Design input 3) dg) = - x 454 Equation 2.a v

y -

12062 ft' . x 454 g'

O.02258

= 2.42E6 {0}

b. The RCS activity needs to be calculated for 60 Cl/g DE l 131. UFSAR Table 11,12 is used to obtain RCS activity, which is based on 1% fuel clad defects per UFSAR Table 11.1 1. The total initial RCS activity is calculated by multiplying the initial concentration by the RCS mass. The initial DE I 131 activity is then determined by multiplying each isotope's activity by its dose conversion factor, summing the values for each nuclide and dividing the sum by the 1 131 dose conversion factor to normalize the activity to 1 131. This DE l 131 activity is the contribution due to 1% fuel clad defects. To determine the activity at 1 pCl/g DE l 131, the fraction of each isotopes contribution to the DE l 131 is calculated and then multiplied by the RCS mass to obtain the corrected total activity in the RCS at i pCilg DE l 131. To obtain the total activity at 60 pCl/g DE l 131, each isotope activity is multiplied by 60, l REVISION NO.: 3 l

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 97 0798.M PROJECT NO. PAGE NO.12 l A,[Ci]= C, xM(g) Equation 2.b.1

. 8 W,(rem]= A,[Cl)x DCF, Equation 2.b.2

.Ci .

DE ll31(Cl]=

- .= 1.39E9(rem # 939.2 (Cl) 1.48E6 DCFnu

'Ci, *l

.C .

Nuclide Concentration at 1

/ DE l-131 = A' g DE 1131 Cl) Equation 2.b.3

/ / x I

Equation 2.b.4 RCS Activity at 1 8 (Ci]= Equation 2.b.3 x8 M(g]x1 .lE6/ Cl, RCS Activity at 60 8 (Cl)= Equation 2.b.4(Ci]x 60 Equation 2.b.5 TABLE 2.b -

Nuclide RCS RCS - lCRP 2 Weighted - . Nuclide RCS Total RCS Total Concent., Activity, Dose Activity, Concent., Activity at Activity at C. As Conversion . Wi . at 1 pCilg i pCilg to pCilg .

(UFSAR (Eq. Factor DCFi (Eq. 2.b.2) (Eq. 2.b.3) (Eq. 2.b.4) (Eq.- 2.b.5 '

Table 2.b.1) [ rom /CI] [ rom] ' .

[ Cilg) . [Cl] [Ci]) '

11.1 2) -- (Cl] (Ref. 23)

[Cile]

l131 2.5E 6 605 1.48E6 8.95E8 0.645 156.1 9.36E3 1132 2.8E 6 678 5.35E4 3.63E7 0.722 174.8 1.05E4 l133 4.0E 6 968 4.00E5 3.87E8 1.032 249.7 1.50E4 l134 6.0E 7 145 2.50E4 3.03E6 0.155 37.5 2.25E3 1135 2.2E 6 532 1.24E5 6.60E7 0.566 137.3 8.23E3 IW 1.39E9 l REVISION NO.: 3 l

I l

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW.97 0798 M PROJECT NO. PAGE NO.13 l

c. The two removal mechanisms for this accident are due to decay and leak rate to the secondary side of 1 gpm. The time dependent activity after two hours with the removal constants can be calculated using the basic decay equation methodology (Refere.nce 10),

dA(t)

= - A dA(t) - AgA(t)

Ad t' '

Al ^A(t)

(I) 0

= l(- A - A }\t o

-t A+A

'd I' '

A(t) = A0e Where : t = 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> = 7200 sec I gpm

ir , Volume of RCS g,g I , I n - - -

A . -""" .x - -

x 1*A tr 3 7 48 60 sec 12062 A l?"I] - ,

= 1.85E - 7 sec - I

d. Since the isotope activity is assumed to remain evenly distributed throughout the RCS volume, then the rate at which the isotope activity leaks from the RCS, R(t), is simply the RCS leak rate times the activity. The total activity released during a given time interval is the integration of the release rate over that interval, in this case,2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

R(t)= 4 x A(t)

R(t) = 4 x A,e(4'4)

R(t)dt = 4A,e(4*AIdt 0 0

= k^n ' _ Q g-i(4+4)dt

-(& + 4)b b^"

R = (A + A)(1-e(4'4)) Equation 2.d l REVISION NO.: 3 l

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 97 0798 M PROJECT NO. PAGE NO.14 l TABLE 2.d RCS Activity at 60 18080Pe Decay. Activity Constant, A. Released, Re Nuclide pCile.

(Equat "~}

(Table 2.b) [Cl) D'I8"g ,".f 12) (C l131 9.36E3 9.97E 7 1.24E1 1132 1.0$E4 8.37E 5 1.05E1 1133 1.50E4 9.25E 6 1.93E1 1134 2.25E3 2.20E 4 1.50E0 1135 ,8.23E3 2.91E 5 9.88E0

e. Calculate the 0-2 hour thyroid inhalation dose at the Exclusion Area Boundary (EAB) In accordance with UFSAR equation 15A 2.

TABLE 2.e ICRP-30 Dose

' Activity Weighted Activity Nuclide Released, 'R'-

D ( gnInpui "'I"d' "' x DCFi (Table 2.d) [Cl) 24) [ rem /Cl] I"*I l131 1.24E1 1.08E6 1.34E7 1132 1.05E1 6.44E3 6.76E4 l133 1.93E1 1.80E5 3.47E6 l134 1.50E0 1.07E3 1.60E3 1135 9.88E0 3.13E4 3.09ES Total I(RixDCFi)sas. 1.72E7 The total DE l 131 activity released is the weighted activity from Table 2.e divided by the 1131 dose conversion factor Numerically this is 15.9 Cl DE l 131 (1.72E7 rem /1.08E6 rem /Cl). The breathing rate is based on 0-8 hour time period.

Exclusion Area Boundarv Dose for 0-2 hours for a 1 com leak rate r S Dm[ rem]= E xBx (Ri x DCF,)w Equation 2.e.1 (Qsm

= 7.7E - 4 x 3.47E -4 x l.72E7[ rem]

.m . ,sec.

= 4.60 (rem]

l REVISION NO.: 3 l

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW.97 0798 M PROJECT NO. PAGE NO.15 l

f. Calculate the thyroid inhalation dose at the Low Population Zone (LPZ) using the equation from UFSAR Section 15A.4. The activity released during the accident from 2 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> was obtained from UFSAR Table 15.14 (as amended in Ref. 22). This activity includes the dose contribution from a 9.4 Opm primary to secondary leakage and the secondary side release.

TABLE 2.f.1 ICRP 30, Dose RCS lodine Activity 2 40 Hour Weighted -

Nuclide Released. Ri,(UFSAR - Conversion Factor' Activity Released, Table 18,14) [Cl)

DC ,( N' x DCFe, [ rom]

4) re /C ]

l131 1.9E3 1.08E8 2.0$E9 l132 3.8E1 8.44E3 2.45E5 1133 1.8E3 1.80E5 3.24E8 1134 3.7E0 1.07E3 3.98E3 1135 3.8E2 3.13E4 1.19E7 Total E(R4 x DCF) 2.39E9 The total 2 40 hour4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> weighted activity calculated above in Table 2.f.1 is separated into specific time periods of 2 8 hrs,8-24 hrs,24 40 hrs. This is based on scaling the total 2 40 hour4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> weighted activity by the fraction of steam released during the same time period. The 2 40 hour4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> steam release was obtained from UFSAR Table 15.13.

TABLE 2.f.2 steam Release, Fraction of Total Weighted Activity.

We g ted Act vity Time Period. (UF8AR Table Steam Release Released in Time -

Me ase ble. '

18.13) [lb) for Time Period q) Period [ rem]

2 8 hr 939,804 0.30 2.39E9 7.17E8 8-24 hr 1,234.515 0.39 2.39E9 9.32E8 24 40 hr 980,808 0.31 2.39E9 7.41E8 Total Steam Total Weighted 3,154,925 2.39E9 Release . Activity Released The atmospheric dilution f actors (X/Q) for 0-8 hrs,8 24 hrs, and 24 40 hrs were obtained from UFSAR Table 15.014. The breathing rates for 0 8 hrs,8 24 hrs and 24 40 hrs were obtained from UFSAR Table 15A 1. Calculate the thyroid Inhalation dose at the Low Population Zonv (LPZ) using the equation from UFSAR Section 15A.4.

r D ug[ rem)= I-3 x 11x Z(R, x DCF,) Equation 2.f.1 s Q s uz l REVISION NO.: 3 l

COMMONWEALTH EDISON COMPANY CALCULATION NO. BRW 97 0798 M PROJECT NO PAGE NO.16 l TABLE 2.f.3 Atmos. - .

Wolghted Dispersion . Breathing Rate,- Activity . LPZ Dose, Dm, Time . Factor, X/Q,4 B,(UF8AR Released, w/ 9.4 opm Leak Period (UFSAR Table Table 18A 1)- IRixDCFi, Rate (Equation 18.0 14) ; [m'/sec]- (Table 7.f.2) 2.f.1) [ rom] .

[sec/m1 [ rom]

0 2 hr 7.1 E 5 3.47E 4 1.67E8' 4.11 2 8 hr 7.1E 5 3.47E 4 7.17E8 17.66 8 24 1.4E 5 1.75E 4 9.23E8 2.28 24 40 7.1E 6 2.32E 4 7.41E8 1.22 Total LPZ Dose -

w/ 9.4 gpm Leak 25.27 Mate [ rom]

'From Tables 2.e and 1.c, [(1.72E7x9,4) + (3.94E6 + 1.60E6) = 1.67E8]

3. CALCULATION OF DOSE DUE TO PRIMARY TO SECONDARY LEAKAGE DURING ACCIDENT INITIATED SPIKE The at Wnt initiated spike model is the same as the pre accident model except an additionallodine appearance rate term is added for fuel release rate into the RCS In accordance with the Standard Review Plan, the reactor trip and/or primary system depressurization associated with the MSLB creates an lodine spike in the primary system. The spiking model assumes that the lodine release rate from the fuel rods to the primary coolant increases to a value 500 times greater than the Technical Specification limit. This factor adds an additional release rate factor for lodine activity,6
a. Calculate the total removal rate of lodine, N, through letdown purification and radioactive decay.

Equation 2 of Reference 18 defines this total as:

sec =Ao 4 Ai t sec + A,(sec ) Equation 3.a.1 F,, t 3 sec Equation 3.a.2 Where : 'Ao t

= x 17

[ REVISION NO.: 3 l

COMMONWEALTH EDISON COMPANY l

l CALCULATION NO. BRW 974798 M PROJECT NO. PAGE NO,17 l l The 75 gpm letdown purification flow F,, is converted from gpm to grams /sec at letdown design

parameters (Design inputs 2 and 3).

~ '

8" I 454 g' Imin'

,1 F' sec , = 75

, min, x x

,7.48 gal; L0.01013 fP, x

Ib ,

,60 sec,

= 4704 1

.sec, Substituting the values of F,, M and DFInto Equation 3.a.2 gives :

4704 1 g 3

-"'" xl1 b sec~',=

2.42E8(g,

( 10s

=1.75E-S sec

TABLE 3.a Letdown Purtf ; . Isotope Decay -. - Total loditis. ~

Remwal Conent, Conent, k .Romway.ek,4 Nuclide

. At o. (Equation 3.a.2) (Design input it) : En,' Loon 3.a.1 -

[sec] ' [sec] - = [sec]

I131 1.75E 5 9.97E 7 1.85E 5 l132 1.75E 5 8.37E 5 1.01E 4 1133 1.75E 5 9.25E 6 2.67E 5 l134 1.75E 5 2.20E-4 2.38E 4 1135 1.75E 5 2.91E 5 4.66E 5

b. The equilibrium fuel release rate,6, is defined as the product of the RCS activity at i pCl/g DE l 131 (from Table 2.b) and the total lodine removal rate for each isotope:

6 (Cl/sec) = A,[Cl) x 4 [sec) Equation 3.b l REVISION NO.: 3 I

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 97 0798 M PROJECT NO. PAGE NO.18 l Each equilibrium fuel release rate is multiplied by 500 (Design input 22) to obtain the spiked release rate.

Table 3.b Totallo3me Fuel Release Spiked Nuclide '

Removal Re, y Raw, M  ; Rekase Rate (Table d3.a)' (Equation 3 b) 600 x 6

[see ] [Cl/sec) ' - [Cl/sec]

l131 1.85E 5 2.89E 3 1.45 l132 1.01E 4 - 1.77E 2 8.85 l133 2.67E 5 6.67E 3 3.34 l134 2.38E 4 8.92E 3 4.46 l135 4.66E 5 6.39E 3 3.20

c. Neglecting the loss terms (radlodecay, leakage and letdown), the time dependent RCS activly due to the accident initiated lodine spike may be written as:

dA(t) = 5004, dt 6 '.

dA(t) = , 500bdt A. O A(t)= A, ^500bt Equation 3.c

d. Since the Isotope activity, A(t) is assumed to remain evenly distributed throughout the RCS volume, then the rate at which the isotope activity leaks from the RCS, R(t), is the RCS leak rate constant, b, multiplied by the activity determined by Equation 3.c. The total activity released during the event is calculated by integrating the release rate over the time interval.

R(t)= 4 A(t)

= 4(A, + 500A,1)

, i.

R(t)dt = , 4(A, + 5004at)dt 0 0 D

R = 4 A,t + 5 04 it Equation 3.d 2 >

l REVISION NO.: 3 l

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 974798 M PROJECT NO. PAGE NO.19 l TABLE 3.d RC8 Activity at 0 2 Hour Activity-Nuclide 1 pCilg, A. -

' '* * . Released, Re (Table 2.b) [CQ fb .bh*Vsec (Equation 3.d) [CQ l131 156.1 1.45 7.16 l132 174.8 8.85 4.27E1 1133 249.7 3.34 1.63E1 1134 37.5 4.46 2.14E1 1135 137.3 'l.20 1.55E1

e. Calculate the thyroid Inhalation dose at the Exclusion Area Boundary and Low Population Zone in accordance with UFSAR equation 15A 2.

TABLE 3.e 0 2 Hour Activity Released. DCFi RxDCF Nuclide:

Ri(Table 3.d) [CQ ' [ rem /CQ [ rem]

li31 7.16 1.08E6 7.73E6 l132 4.27E1 6.44E3 2.75ES l133 1.63E1 1.80E5 2.93E6 l134 2.14E1 1.07E3 2.29E4 l135 1.55E1 3.13E4 4.35E5 I(RixDCFi) 1.14E7 The total DE l 131 activity released in 0 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> is the total weighted activity released, I(R,xDCF), from Table 3.e divided by the 1131 dose conversion factor. Numerically this is 10.6 Cl DE l 131 released in the first two hours (1.14E7 rem /1.08E6 rem /Cl). The breathing rate is based on the 0-8 hour time period.

Exclusion Area Boundary Dose for a 1 com lets i&'c:

r S Dm(rem]= b xBx (R i xDCF.) Equation 3 e.1 sQsm 3-

= 7.7E - 4 *---

$m x, 3.47E - 4 SCC, x1.14E7(rem]

= 3.05 (rem]

l REVISION NO.: 3 l

l COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 97-0798.M PROJECT NO. PAGE NO. 20 l

f. Calculate the thyroid inhalation dose at the Low Population Zone (LPZ) using the equation from UFSAR Section 15A.4 The activity released during the accident from 2-40 hours was obtained from UFSAR Table 15.14 (as amended in Ref. 22). This activity includes the dose contribution from a 9.4 gpm primary to secondary leakage and the secondary side release. ,

I TABLE 3.f.1 l

' lGitP 30, Dose -

. RCS lodine Activity : -

2 40 Hour Weighted ~.

Nuclide Released, R4,(UF8AR

. Cersion Factor, Activity Released, DCF,(Des nput Table 15.14) [Cl] Re x DCFe, [ rem] -

I131 2.1E3 1.08E6 2.27E9 l132 1.0E3 6.44E3 6.44E8 l133 2.9E3 1.80E5 5.22E8 1134 1.4E2 1.07E3 1.50E5 1135 1.2E3 3.13E4 3.76E7 Total E(R x DCF,) 2.84E9 The total 2 4C, hour weighted activity released calculated above in Table 3.f.1 is separated into specific time periods of 2 8 hrs,8 24 hrs, and 24 40 hrs. This is based on scaling the total 2 40 hour4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> weighted activity released by the fraction of steam released during the same time period.

The 2 40 hour4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> steam release was obtained from UFSAR Table 15.13.

TABLE 3.f.2 Steam Release, Total 2 40 Hr '

Weighted Activity Fraction of Total Weighted Activity Time Period - - (UFSAR Table Steam Release : Released in Time for Time Period N' '*d

  • 15.1-3) [lb] - 3 Period [ rem] -

2 8 hr 939,604 0.30 2.84E9 8.52E8 8 24 hr 1,234,515 0.39 2.84E9 1.11E9 24-40 hr 980,806 0.31 2.84E9 8.80E8 Total steam Total Weighted 3,154,925 2.84E9 Release Activity Released The atmospheric dilution factors (X/Q) for 0-8 hrs,8 24 hrs, and 24-40 hrs were obtained from UFSAR Table 15.014. The breathing rates for 0-8 hrs,8-24 hrs and 24-40 hrs were obtained from UFSAR Tabie15A 1, Calculate the thyroid inhalation dose at the Low Population Zone (LPZ) using the equation from UFSAR Section 15A.4.

l REVISION NO.: 3 l

i i

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW.97 0798 M PROJECT NO. PAGE NO. 21 l r

Duz(rem)= 8- S x B x[(R, x DCE) Equation 3.f.1

( Q suz TABLE 3.f.3 I

Breath'ing Rate. LPZ Dooe, Dm, w//

Time Di n.

_. Factor, X/Q,1 - 5 (UPSAR W'I( '

a 9.4 gpm Leak Period , l(R xDCFi), - p,,, ggq,,gg,,

(UPSAR Table Table 18A 1)s-1[m'/eec] , -(Table 3.f.2) 3,,,99 g,,,j

.18.0 14)1 I'**I feecim T 0 2 hr 7.1E5 3.47E 4 1.13E8' 2.78 2 8hr 7.1 E.5 3.47E 4 8.52E8 20.99 8 24 1.4E 5 1.75E 4 1.11E9 2.72 24 40 7.1E 6 2.32E-4 8.80E8 1.45'

! Total LPZ Does w/ a 9.4 LeakL 27.94 Rate [ rom] '

'From Tables 3.e and 1.c [(1.14E7x9.4) + (3.94E6 + 1.68E+6) = 1.13E8]

4. CALCULATION OF SITE ALLOWABLE LEAK RATE
a. Results of the Pre Accident lodine Spike Model The EAB dose for a 9.4 gpm leak rate is 44.74 rem (4.60 X 9.4+1.50). The total LPZ dose calculated in Table 2.f.3 is 25.27 rem. Therefore, the EAB dose is more limiting.

The thy old dose due to the release of activity in the secondary side of all four steam generators is 1.50 rem (page 10). The dose due to 1 gpm primary to secondary leakage in 4 steam Generators with a concentration of 60 Cl/g is 4.60 rem (page14). Given that the dose limit in the Standard Review Plan is 300 rem for the pre accident model, the maximum allowable leak rate without exceeding 300 rem is:

e 3

'** I'"

Allowable Leak Rate =

4.60 "

s SPm j

= 64.89 gpm l REVISION NO.: 3 l

)

COMMONWEALTH EDISON COMOANY l CALCULATION NO. BRW 97-0798 M PROJECT NO. PAGE NO. 22 l Consequently, the total EAB dcse due to a 64.89 gpm leak during a MSLB is 300 rem. Allowing 0.1 gpm room temperature leakage per each of the three intact steam generators leaves 64.47 gpm (64.89-0.3x1.406) for the faulted loop.

Note that the 64.89 gpm allowable leak rate is calculated at RCS operating conditions. Should the allowable leak rate be desired to be expressed at rosm temperature conditions, the 64.89 gpm must be divided by 1.406 (Reference 19) to account for RCS density differences.

Therefore, the room temperature allowable leak rate is 46.15 gpm.

b. Results of the Accident initiated lodine Spike Model The EAB dose for a 9.4 gpm leak rate is 30.17 rem (3.05 x 9.4+1.5). The total LPZ dose calculated in Table 3.f,3 is 27.94 rem. Therefore, the EAB dose is more limiting.

The thyroid dose due to the release of activity in the secondary side of all four steam generators is 1.50 rem (page 10). The dose due to 1 gpm primary to secondary leakage in 4 steam Generators with a concentration of 1 Cl/g is 3.05 rem (page 19). Given that the dose limit In the Standard Review Plan is 30 rem for the accident inillated spike model, the maximum allowable leak rate without exceeding 30 rem is:

4 e 8 30 rem-1.50 rem Allowable Leak Rate =

3.05 "

s gpm j

= 9.34 gpm Consequently, the total EAB dose due to a 9.34 gpm leak during a MSLB is 30 rem. Allowing 0.1 gpm room temperature leakage per each of the three intact steam generators leaves 8.92 gpm (9.34 0.3x1.406) for the faulted loop.

Note that the 9.34 gpm allowable leak rate is calculated at RCS operating conditions. Should the allowable leak rate be desired to be expressed at room temperature conditions, the 9.34 gpm must be divided by 1.406 (Reference 19) to account for RCS density differences. Therefore, the room temperature allowable leak rate is 6.64 gpm.

l REVISION NO.: 3 l J

COMMONWEALTH EDISON COMPANY l CALCULATION NO. BRW 97 0798 M PROJECT NO. PAGE NO. 23 l

6. CALCULATION OF END OF CYCLE 7 PREDICTED DOSES in accordance with the requirements for Braidwood Unit i voltage based repair criteria (IPC) for outer diameter stress corrosion cracking at tube support plates, the potential tube leakage during a MSLB event with containment bypass must be predicted at the end of the next operating period. In addition to the predicted IPC leakage, the MSLB leakage contribution from circumferential cracking at the top of the tubesheet must also be factored into the end of cycle assessment. This combined predicted leak rate must be compared to and shown to be less than the maximum site allowable leak rate determined in Section 4 above.

Braidwood Statica is currently preparing a request for Technical Specification change to lower the RCS Dose Equivalent lodine -131 limit to 0.1 pCl/g. As documented in Section 3, the site allowaL!e leak rate of 6.64 gpm at room temperature conditions is based on an RCS DE 1131 limit of 1 Cl/g. The site allowable leak rate can be increased proportional to a reduction in RCS DE 1131. Therefore by reducing the RCS DE 1131 limit to 0.1 Cl/0, the allowable leak rate at room temperature conditions is increased to 66.4 gp:n (6.64 gpm/0,1).

The predicted end-of cycle 7 IPC leak rate is 57.1 opm based on room temperature conditions (Design input 25). To thir is added 5 gpm to account for the contribution from circumferential cracking at the top of the tube sheet and operationalleakage from three steam generators (0.1 gpm per steam generator) for a total leak rate of 62.4 gpm at room temperature conditions. This is bounded by the requested 66.4 l gpm site allowable leak rate limit at room temperature conditions.

This section of the calculation determinet the EAB and LPZ thyroid dose for the predicted end-of-cycle leak rate of 62.4 Opm to validate that the currerd operating conditions are bounded by existing calculations. The EAB and LPZ dose is bounded by Section 3 of this document, which showed that the accident initiated spike is the limiting accident.

a. The most restrictive EAB thyroid dose limit is 30 rem per section 4.b (page 22). This dose limit corresponds to an allowable leak rate of 6.64 gpm at an RCS DE l-131 concentration of 1 Cl/g.

The calculated EAB dose remans the same when allowable leakage is increased to 66.4 gpm because RCS DE l 131 is decreased by a proportional amount. The EAB dose, XeAa, due to current cycle projected leakage of 62.4 gpm is calculated by performing a ratio of calculated values to projected vaines.

62.4 gpm _ Xm 66.4 gpm ~ 30 rem 62.4 gpm 30 rera 66.4 gpm Xm = 213.2 rem at a 0.1 Ci/g RCS DE1131 concentration Therefore, the end-of cycle 7 predicted EAB dose is within the 30 rem dose limit under end-of-cycle 7 operating conditions.

l REVISION NO.: 3' l l

COMMONWEALTH EDISON COMPANY

[ CALCULATION NO. BRW 97-0798 M PROJECT NO. PAGE NO. 24 l

b. The LPZ calc..'ated thyroid dose is 27.94 rem per Section 3.f (page 21). This dose limit corresponds to an allowable leak rate of 6.64 gpm at an RCS DE l 131 concentration of 1 Cl/g, which again remains the same under the proposed allowable leak rate of 66.4 gpm because RCS DE l 131 is reduced to 0.1 pCl/g DE l 131. The LPZ dose for projected end-of-cycle conditl0ns, Xgz, is calculated by performing a iatlo of calculated values to projected values.

62.4 gpm , Xm 66.4 gpm 27.94 rem A Spin 27.94 rem Xuz = 66.4 gpm Xuz = 26.26 rem at a 0.1 p Ci/g RCS DE I-131 concentration Therefore, the end-of cycle 7 predicted LPZ dose is within the 30 rem dose limit under end-of.

cycle 7 operating conditions.

SUMMARY

AND CONCLUSIONS It is concluded from Section 4 that the accident initiated spike is more limiting, therefore the maximum site allowable SG leak rate during a postulated MSLB is g.3 gpm at RCS operating conditions (6.6 gpm at room temperature) with a RCS DE l 131 concentration of 1 Ci/g. This value includes the 0.1 gpm contribution from each of the three intact SGs.

Section 5 determined that the Unit 1 end-of cycle 7 pret ided MSLB tube leakage results in off site thyroid doses that are less than a small fraction (10%) of 10CFR100 limits, The resulting EAB and LPZ -loses, with a 0.1 pCl/0 RCS DE l-131 limit, are 28.2 rem and 26.26 rem, respectively, which are less than the 30 rem limit for the limiting accident initiated splke case.

- FINAL -

l REVISION NO.: 3 l

. _

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