L-79-347, Responds to Re Containment Purge Issue.Forwards C-E ECCS Performance Evaluation,Assessment of Radiological Release from Containment & Discussion of Containment Purge Isolation Instrumentation & Control Circuit Designs

Responds to Re Containment Purge Issue.Forwards C-E ECCS Performance Evaluation,Assessment of Radiological Release from Containment & Discussion of Containment Purge Isolation Instrumentation & Control Circuit Designs

ML17207A666
Person / Time
Site:	Saint Lucie
Issue date:	12/13/1979
From:	Robert E. Uhrig FLORIDA POWER & LIGHT CO.
To:	Reid R Office of Nuclear Reactor Regulation
References
L-79-347, NUDOCS 7912200408
Download: ML17207A666 (31)

Text

REGULATORY I RMATION DISTRIBUTION SYS1 (BIDS)

ACCESSION NBR e 7912200408 DOC ~ DATE i 79/12/13 NOTARIZED:

YES F'ACIC;So-335 St. Luc/e Planti Unit ii Florida Power L'Light Co.,

AOTH;NAME 'AU'THOR AFFILIATION UHAIGgR ~ ED Flo.iida Power" L Light Co, REC IP, NAME RECIPIENT AFFILIATION Of f >ce of Nucfeal Reactor Regulation

SUBJECT:

Responds to 781129 1 tr re containment purge issue,Forwards C

E ECCS performance evaluationiassessment of radiological release from containment 8 discussion o,f containment purge isolation instrumentation 8 control 'circuit designs, DISTRIBUTION CODE:

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Office of Nuclear Reactor Regulation Attention:

Mr. R.

W. Reid, Chief Operating Reactors Branch g4 Division of Operating Reactors U.

S. Nuclear Regulatory Commission Washington, D.

C.

20555

Dear Mr. Reid:

FLORIDA POWER 8 LIGHTCOMPANY December 13, 1979 L-79-347 Re:

St. Lucie Unit 1 Docket No. 50-335 Containment Pur e

References:

(1)

NRC letter dated September 27,1979 from Darrell G. Eisenhut to All Light Water Reactors (2)

NRC letter dated October 23, 1979 from R.

W. Reid to R.

E. Uhrig (applicable to Docket No. 50-335)

In response to your letter of November 29, 1978, several analyses/evaluations have been performed in an effort to resolve the contai nment purge issue.

A description of this effort, which is responsive to references (1) and (2), is given below.

In order to bound the worst case purge mass release, two different purge valve closure scenarios were examined.

The first assumed no single failure, i.e.,

complete operability of all six pur ge valves and an arbitrarily slow valve closure time of ten seconds.

This yielded a calculated mass loss of 5224 pounds of air from the containment.

The second case conservatively assumed the worst single failure (a complete contai nment isolation signal train failure),

a Technical Specification purge valve closure time of five seconds, and a delayed purge valve closure initiation time of 2.3 seconds.

This case resulted in a calculated air mass loss of 5104 pounds.

Attachment 1 represents Combustion Engineering's Emergency Core Cooling System (ECCS) performance evaluation documenting the effect of containment purging using the higher mass release scenario. 'his evaluation clearly shows that the impact of purging on ECCS performance is small with only a 26 F increase in peak clad temperature.

An'ssessment of the radiological release from contaianent through the closing purge valves is presented in Attachment 2.

The results clearly indicate that any potential dose increase is small and well within the limits of 10 CFR 100.

Attachment 3 discusses the containment purge and isolation instrumentation and control circuit designs.

It demonstrates that the appropriate separation and single failure criteria are satisfied.

goSY 5

y 91SSGO~O~

PEOPLE... SERVING PEOPLE

la Office of Nuclear Reactor ul ation.

Page 2

Finally, in order to demonstrate purge valve integrity under postulated accident transients, FPL (through Ebasco Services, Incorporated) has contracted with the valve manufacturer (Henry Pratt Company) to perform the necessary analyses.

The results of the analyses are antici pated by June 1980-'owever, for the interim period, FPL, in consultation with Henry Pratt

Company, has determined that satisfactory operability under accident transient conditions is expected when purge valve opening is limited.

A plant change/modification is being processed,to implement a purge valve modification restricting the valve opening to a maximum of 50 degrees.

I'n addition, the containment purge system'was previously evaluated with respect to I 8

E Bulletins 79-01 and 79-01A.

The FPL response concerning the ualification of class lE electrical equipment was sent to you on July 2, 1979 L-79-181).

As indicated then, the investigation for data identified problems relating to qualification documentation for AVCO solenoid valves and NAMCO limit switches, which have an application on the containment purge supply and exhaust valves.

Despi,te the lack of initial test data, the construction of the valves and materials utilized therein can withstand the initial seconds of the containment environment following a LOCA.

The use of NAMCO switches on

'he purge valves does not affect the ability of the valves to close.

In spite of a potential lack of position indication of the valves in, containment, those purge valves that are not located in the post-containment environment will show actual position.

However, in order to provide additional safety margin and to ensure long term solenoid valve operation and purge valve position indication, FPL has ordered replacement solenoid valves and limit switches which are post-LOCA qualified.

These will be installed at the first available opportunity following their receipt.

In conclusion, Florida Power 8 Light Company plans to operate the containment purge system in compliance with our letter of May 25,

1979, which contained a

commitment to limit containment purging at St. Lucie Unit 1 to 90 hour0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br />s/year in operational modes 1 and 2, until such time as the 50 degree modification is implemented.

The effect of purging on ECCS performance and radiological dose has been shown to be minimal.

The results of the valve integrity evaluation, to be performed by the valve vendor, are expected to be available by June, 1980.

We will continue to keep you informed of our progress in this matter.

Very truly yours, Robert E. Uhrig Vice President Advanced Systems 8 Technology REU/MAS/cph Attachments cc:

J.

P. O'Reilly, Region II Harold Reis, Esquire

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0 St. Lucie Unit'1, Cvc'.e III'CCS Perfori>>ance valuation filth and Wit!;out Containmont Purging l.o

. Ir'TPODUCTION AND SU'MRY The ECCS performance calculations for St. Lucie Unit 1 presented herein demonstrate appropriat conformance with 10CFR50.46 which pr sents the Acceptance Criteria for Emergency. Core Cooling Systems for Lioht '<tater.

Cooled Reactors This evaluaticn report documents the results of'wo-separate ECCS performance analyses for St. i ucie Unit 1.

A one break analysis using Core Cycle 3 specific data.

was performed to demonstrate acceptable ECCS performiance at a Peak 'near Heat Generation Rate (PLHGR} of 14.8 kw/ft for St. Lucie Unit 1, Cycle 3.

Reference 10'resented an ECCS evaluation for Cycle 3 which by demonstrating that, the Cycle 2

FCCS performance analysis 'as bounding for Cycle 3 justified a Cycle 3 PLHGR of 14.8 kw/ft.

Reference 10 did not, however, contain a

Cycle 3 specific analysis.

A penalty of 0.12 kw/ft was imposed limiting

'ycle 3 to a PLHGR of '}4 68 kw/ft pending a Cycle 3 analysis.

The results of such an. analysis are docum nted in this report and justify operation of Cycle 3 at a

PLHGR of 14.8 kw/ft In response to Reference 2 a second one. break analysis was performed, also using Cycle 3 specific data, to determine the effect on ECCS per-formance 'oi containment pu. ging.

Th results of this analysis demcnstrates 1

that the ECCS perf.ormance for St. Lucie Unit 1, Cycle 3 is acceptable at a

PLHGR of 14.8 kw/ft for a LOCA initiat d during containment purg',ng.

2 0 HETHOD OF ANALYSIS The analyses were performed using the approv d C-E large break evaluation model The b. eak size and type, 0.8 D"3/PD~, is the same as

• 0.8 x Double-Ended Slot Break in the Re ctor Coolan Pu;ip D',scnarge Leg

O ai ',,

.(a.s) was analyzed for th= St. Lucie Unit 1 Cycle 2

ECCS pe~~...ance

=valuation Both analyses used St. Lucie Unit,l Cvcle 3 sp cific d=-ta for input.

The major differences in the input data between Cycle 2 and Cycle 3 are:

1.

A'conservative approach was empldyed to generate the initial fuel stored energy.

This approach resulted in a 16 F increase (over the Cycle 2 value) in the hot spot fuel average temperature for Cycle 3.

2 The radial power distribu+ion used in the thermal rod-to-rod radlatson-model is less limiting for Cycle 3.

Table 1 compares the important system parameters for both core cycles.-

The analysis without containment purging'sed the exact same methodology as employed for the Cycle 2.analysis Because

~he

~wo input data chang s

. (4,s) ca only affect the clad temperature (STRIKIH-II) and hence the cnre wilde clad (6) oxidation {CONZIRC)'

calculations, the blowdown (CEFLASH-4A) and

'g)

{y)-.

refill/reflood

{COlRPERC-II) calculations employed in this analysis are the same as docu..ented in References 4 and 5

The analysis with containment'urging employed the same methodology and input data as described above.

The effect of the mass loss through the purge system was modeled by reducing the i~i ial containment pressure..

Separate COYiPERC-II, STRIYIN-II, and COIIZIRC calculations mere then performed.

CEFLASH-4A results are not affected by changes in initial containment pressure since break flow remains critical throughout the 'blowdown. period.

Reference 11 documents the amount of air lost 'from the containment via the t

\\

purge ]in.s (one intake and one exhaust).

The containment, pressure transient from the Cycle 2 analysis' was used to determine the flow rate.

The.

purge'g) system isolation valves were assumed to start closing at 0.8 seconds and be fully closed at 10.8 seconds following the break Figure 1 presents the total

-flow rate versus time or both lines.

The vlow rate is based on the cgnservative assumpt'.on

+hat.only air was flowing through the puro l~nes.

1 a

n 1

In ne

~al "ulation o> the containm>ent press re, thc to air m>zss expelle

" t~

~d bv integrating the f1o;r rate versus

~ >,e function Tnis mass of'ir (5224 ibm) was then subtracted from the initial containm nt a>r r-ass and a new initial pressure determined.

This r;>ethod exaggerates ne eY Tee+

on h

con ainmen" pressure for the first ten seconds Since the containment pressure is not an important paraqieter un~>1 a> ~er 20 seconds into the transient (after blowdown is over), the difference as determined by eak clad temperature,'f rer,",oving the total mass expelled at the begznnsng versus removing it over a 10.8 second period is only slightly conservative 3.0 RESULTS Times of interest and significant results are summ>amazed an Table 2.

The results for both ana'lyses are presented graphically in the figures listed in Table 3.

C As stated in Section 2.0, these analyses used data specific to St Lucie Unit 1, Cycle 3.

The analysis without purging therefore can be compared to the Cycle 2 ECCS analysis 'o show the effect of Cycle 2 to Cycle 3 data changes

~

The resulting Peak Clad Temperature (PCT) of 1872 F for Cycle 3 is over 150 F lower than, the Cycle 2 PCT (2035'F) and demonstrates

. acceptable ECCS per>ormance for core Cycle 3 at a PLHI R of ]4.8 kw/ft.

The analysis with containment purging r'esulted in a PCT of 'l898'F, demonstrating that a

PLHGR of '14.8 kw/ft is also acceptable in terms of ECCS performance if the LOCA occurs during purge ng opera a on.

The 26 F

difference in PCT (1898 F 1872 F) between the two arialyses shows that the impact 0> containment purging on FCCS performance Js smar r Tol St. J.uci 'nit ),- Cycle 3.

ca

'."PER."-.ACES l.

Acceptance Criteria for Er:..ergency Core Cooling Syst ms for Ligh -nater Cooled nuclear Po'i;er Reactors, Federal Register, Vol. 39, No. 3, Friday, January 4, 1974.

2.

Letter, from R.

M. Peid (fiRC) to R

E. Uhrig (FPEL), Subject=

"Containm nt Purging During I'ormal Plant Op ration",

Do ket Ho. 50-335, 11/29/78.

CEHPD-132, "Calculative Yiethods for the CE,Larg Break LOCA Evaluation Model", August 1974 (Proprietary}

CEhPD 132, Supplpment 1, "Updated Calculative thethods for the CE Large Break LOCA Evaluation t)odel",

December 1974 (Proprietary).

l CEi<PD-'132, Supplement 2, "Calculational hethods for the CE Large Break LOCA Evaluation i)odel", July 1975, (Proprietary).

Transmittal 'of F-LOCA-78-005 (R.H.Uhrig to V.Stello, March 22, l978)

Transnittal of F-,LOCA-78-017 (R.H.Uhrig to V.Stello March 22, 1978)

'I

. CEHPD-135, "STRIi'IH-II,.A Cylindrical Geometry Fuel Rod iieat Transfer Program, April 1974 (Proprietary).

CEHPD-]35, Supplement 2, "STRIVE.'!-II, A Cylindrical geometry Fuel i Rod Heat Transfer Program (jiodification)", Feb> uary 1975 (Proprietary)

CEhPD-T3'5, Supplement.4,

",STRIKIH-II, A Cylindrical 6 om try Fuel Pod Heat T) ansfe1 Progr am", August 1976 (Proprie ary}.

CE>>PD-135, Suppl m nt 5;'"STRIKING-II, A Cylindrica'i Ceome ry Fu 1

P.-d Heat Transfer Program",

August 1976

(. rnprie ary}.

7.

C-"f>PD-] ~

"C~ r LA"i!"4R, A FORTR.-";4-~ V Oigital Cc:"%e>

Prog r

f Reactor Bloi;co~n Analysis", April 1974 (Proprietary).

I CEhPD-133 Supplement 2,

"C FLRSH-4A, A FO."-.TPPf'l-IV D i gital Computer Program Tor Reactor Blo:;:do;~n Analysis (tlodirication)", Dec mber 'l974 (Proprietary); '-

8.

CEHPD-134, "COhPERC-II, A Program for Em rgency Pefill-tcef]ood of the Core", April 19N {Proprietary)

P 9.

'CEhPD-134 SUpplement 1

"COlIP PC-II, A Program for Enargency. Refill-1 Ref lood of the'Core (tlodification)", December 1974 (Proprietary)

/

I 10.

Transmittal of F-LOCA-79-002 (FPL letter L-79-45,- l"ebruary 22, l979)

Letter, ASS-l-,79-01, from L J.

Sas (Ebasco) to A. S.

Bameson (CE),

6/4/79.

lab le St. Lucie Unit 'I General Systemi Parameters guanti ty Val ue.

~Cele Ill

~Cele II Reactor Power Level (102" oi Nominal)

Averaoe Linear Heat Rate Noderato:- Temperature Coefficient at Initia'I D nsity System Flow Rate (Total )

Core Flo>v Rate Initial System Pressure Core Inlet Temperature Core'Outle Temperature i

Active Corp Height Fuel Rod OD Number of Cold Legs

'umber vf'ot Legs Cold Leg Diameter Hot Leg Diameter Safety Injection Tank Pressure Safe y Injection Tank Gas/Mater Volume Peak Linear Heat Generation Rate

{PLHGR)

Gap Conductance at PLHGR Fuel Centerline Temperature at PLHGR Fuel Average Temperature at'LHGR Hot Rod G'as P res s u re Hot Rod Burnup 2611 i.6.0956

+0. 2x10 a

'139.44xl0 6 134.6xl 0 2250 548

~.'98 11 39 0.44 2

30

, 42 215 930/l090 14.8 1525 3512

.-1031 820

+0. 2xl 0 139.4axl 0 134.6xl0 2250 548

'll 39

'0 pa, ap/

F lbs/hr lbs/hr psia oF oF ft in 2

30 42

. 2'I5 930/1090 14.8 1552 3484 2181 1048 820 in 1n ps 1 a fJ 3 kw/ft BTU/hr-F oF psia I"iÃD/i~iiTI 2611 YiMt 6.2126 k~/ft'

Ta Dle St. Lucie Unit II Sun-ary of Analytical B sulcus Times ot Inter st (seconds)

Hot Rod

~Rv tvre SI Tanks On Start or Re flood SI Tanks

~Emt Mithout Purge Mith Purge 55.5 52.8 17.6 17.6 35.8 35.8 63.3 63.2 Resul ts PCT ~F Local Zirc.

Core Mide Zirc Hithout Purge Mith Purge 18?2 1898

6. 81 7.24

<0.515

~0.649

~ ~

0 Tab e

3 St. Lucie Unit II Ana.lysis Plo s

Variable Fioure Number Conta)nment Press'ure*

Hass Added to Core During Reilood*

Peak Clad Temperature*

Rupture Node Peak Clad Temperature-Local Clad Oxidation*

Hot Spot Gap Conductance*

Hot Spot Heat Transfer'Coefficient*

'ot Rod Internal Gas Pressure C1ad Temperature; Centerline Fuel Temperature,

-Average Fuel Temperature, and Coolant Temp rature

<or Hottest trode (vlithout puroing)

Clad. Temperature, Centerline Fuel Temperature, Average F'uel Temperature, and Coolant Temperature for Hottest Node {With purging) 6 7

8 9

10

• Figure presents results for both analyses.

II I

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" TINE, SECONDS r"florida PP=L Co.

S c. Luci8 PIBAt t.fait Nt.:mbet I

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CYCLE 3 CONTR I Hi'iii'lT PRESSURE

4'iTI.OUT PURGE

<OXU 20XQ 8

0

. TIJ<E, SECONDS r=larida P~L Co.

~>+. LUc)B f IBi"lc UAl c +1L)i Ab~f CYCLE 3 j'ASS fQi3iH) TO CORE BUR1I~G BEFLOOD

)ARITH PVRGE vmeuT F uRt;E

-')N TI!iF, SECO!lDS

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-3iCO WITH PURGE H1TI.DUT'URGE TIi-',E, SECO;~OS FIol-icosa Fc"" L Co.

St,. L uc,'~.'ant unit l'-u-i-"

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PFAK CLAD TEi'lr'PATUP,;,

RUPTURE ZOHE C'(CLE ""

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Nl iran PUr~SE H1TrOUT PURGE l0 C9

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t TIl'lE, SECOI~DS LOCAL CLAD 0XtBPTIOh'YCL E 5

1t-IQJ h1TH PURGE s'sITt GUT PURGE j.DXJ l~rt~

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0 TItiC, SLCO,'nS

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I HOT SPOT 6AP COi"DUCT&!"CE Ch't LE Fl i 3t 'I

l20

WITH PURGF, HITrQUT PL~IDGE 20 0

0 TIi'IE, SECONDS HOT SPOT HVT TR".1'lSFER COFFF I CIENT

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=103l.3 PSIA 1MJ TLAT

'fUTH PURGE HIT'DUT PURGE 52.8 SEC iHUPTURE 200 0

0 20 LIO TIflE, SECONDS

-torida Pc= L Co.

St. LucIe Fiant Unt. )~lUmber I

CYCLE 5 HOT ROD I~i EPl'4 6AS PRESSURE Figure 0

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. St. Lucie Unit 1

'ost LOCA R diological Assessment

-1!ith Containment Purging The radiological doses due to a postulated

~<ss of Coolant Accident (LOCA)'ave been previously established and documented in the FSAR (Appendix 68).

At that time it was assumed that no containment purging the accident.

was occurring at the onset of This assessment includes t1>e dose increment due to the operation of the purge I

" system.

The assumptions used in the evaluation of the dose increment are as follows:

1.

Purge valve closure is completed in 7.'3 seconds from the onset of the LOCA; 2.

No fuel failure is assumed to occur during the time interval of valve

,closure, i.e'., 7.3 seconds; 3.

The primary coolant iodine activity corresponds to the maximum limit of 60 pci/gm, dose equivalent; 4.'00% of the blowdown from the FSAR worst case break (1.0 x DES/Ps)*

'lashes to steam.

All the iodine in the flashed steam is assumed to become airborne; 5.

The flow through the purge valves is base on air considering the worst.

case scenario resulting in a 510~> pound mass loss; 6.

All other relative assumptions are in accordance with the FSAR.

The results of the evaluation are nresented below:

Offsite Th roid Dose RE1)

Location Site Boundary (ZAB) (0-2 >>ours)

LOCA 66.0 Increment due to Pur in 12.8 Tota1

78. 8 Low Population Zone (LPZ) (30 days) 150-0 6.1 156.'

Offsite hhole Bo~d Dose (lIlE~l Site Boundary (EAB) (0-?hours) 4.0 0.08 Low Population Zone (LPZ) (30 days) 5.5 0.04 5.54 As clearly indicated, the anticipated doses attributable to a LOCA occurring during purging operation is'well within the limits of 10 CPR 100 in the most conservative sense.

A realistic anticipated iodine dose equivalent is less than 1 pci/gm which would result in a'n offsite B.ose increment due to purging of orders of magnitude less than shown above.

-"Double Ended Slot Break at the Pump S ction (9.82 ft.

).

2'

St,- Lucie Unit 1 Conta'nment Purge and Isolation Instrumentation and Control Circuit Design The containment purge valves are situated in two separate flow paths (FCV-25-1,

-2,-3 and FCV-25-4,-5,-6).

These valves are closed upon an engineered safety features actuation systems (ESFAS) initiation of containment isolation.signal (CXS) through de-energization of the control solenoids associated with each valve.

The ESFAS is designed in accordance with XEEE 279 1971 as discussed in FSAR Section 7.3.1.4 and 7.3.2.3.

The ESFAS provides two (2) independent (physically and electrically isolated) actuation paths to initiate and complete containment isolation.

These are CXS 'A'nd CXS

'B' CXS 'A'e-energizes the solenoids thereby causing them to vent and close valves FCV-25-1,-3,-5 while CXS

'B'e-energizes the solenoids causing valves FCV-25-2,-4,-'6 to close in a similar fashion.

Operation of either'A'r 'B'rain will effect the isolation of both containment purge paths.

\\

Xn addition, the review of the design of the safety actuation signal circuits that incor'porate a manual override feature, previously reported to the NRC via our submittal of January 5, 1979, confirmed that existing physical features are provided to facilitate adequate administrative controls.

Overriding one

)

safety actuation signal does not cause the bypass of any other safety actuation signal.

STATE OF FLORIDA

)

)

COUNTY OF DADE

)

ss

~

Robert E. Uhrig, being first duly sworn, deposes and says:

That he is a Vice President of Florida Power

& Light Company, the Licensee herein; That he has executed the foregoing document; that the state-ments'made'in this said document are true and correct to the best of his knowledge, information, and belief, and that he is authorized to execute the document on behalf of said Licensee.

Robert E. Uhrig Subscribed and sworn to before me this day of NOTA Y PUBLIC, in an State of Florida Ny commission expires:

for the county of Dade, Notary Public, State of Prorata ar Large My Commission Expires May 5,

1881 Bonded thru Maynard Bonding Agency

1 E,

C