TXX-9232, License Amend Request 92-003 to License NPF-87,replacing Wflash Computer Code W/Notrump Computer Code for Small Break LOCA ECCS Evaluation Model

License Amend Request 92-003 to License NPF-87,replacing Wflash Computer Code W/Notrump Computer Code for Small Break LOCA ECCS Evaluation Model

ML20114D678
Person / Time
Site:	Comanche Peak
Issue date:	09/03/1992
From:	William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20114D680	List: ML20114D681 TXX-9232, License Amend Request 92-003 to License NPF-87,replacing Wflash Computer Code W/Notrump Computer Code for Small Break LOCA ECCS Evaluation Model
References
TXX-92323, NUDOCS 9209090249
Download: ML20114D678 (13)

Text

.. - _ _ _ _ _ - ___ _ _ . - _ _ _ . - _ _ _ _ _ . _ _ _ _ _ _ _ . _ _ .

Log # 1xX-92323 lF""

~ -

. File # 916 (6)

Ref. # 10CFR50.90 1UELECTRIC September 3, 1992 wmlam J. Cohm Jr, amp he fresidner .

V. S Nuclear Regul6 tory Commission t Atta: Document Control Desk ,

Washington, DC 20555

$UBJECT: C0HANCHE PEAK STEAM ELECTRIC STATION (CPSES) - UNIT 1 DOCKET NO. 50-445 LICENSE AHENDHENT REQUEST 92 003 REPLACEMENT OF THE.WFLASH C0HPUTER CODE WITH THE NOTRUMP COMPUTER CODE FOR THE SHALL BREAK LOSS OF COOLANT ACCIDENT (LOCA) EMERGENCY CORE COOLING SYSTEM (ECCS) EVALUATION H0 DEL Gentlemen:

Pursuant to 10CFR50.90, TV Electric hereby renuests an amendment to the CPSES Unit 1 Operating License (NPF 87) by incorporating the enclosed change into the CPSES Unit 1 Technical Specifications.

The proposed change involves replacement of the analysis of record for the CPSES Unit 1 Small Break LOCA. The change replaces the 1976 Small Break

-LOCA evaluation model using the WFLASH computer code with the 1985 Small Break LOCA evalurtion model using the NOTRUMP computer code.

This change is being requested because the Small Break LOCA Peak Cladding Temperature (PCT) i s greater than 2200 F when the PCT penalties (due to plant modifications and analysis changes) are added to the base PCT calculated by the 1975 evaluation model. To obtain a PCT of less than 2200*F, the event '

needed to be reanalyzed with the plant modifications and analysis changes incorporated, or a new analysis needed to be performed using a more current model. Since Westinghouse was already using the more advanced 1985 Small Break LOCA evaluation model with the NOTRUMP computer code to perform new analyses and update existing analyses for other plants, as well as CPSES Unit 2, TV Electric. decided that the analysis of record should be changed to the.1985 Westinghouse evaluation model.

Upon receiving written notification from Westinghouse on July 14, 1992, TV Electric orally reported th* PCT exceeding 2200*F in accordance with 10CFR50.46 and 10CFR50.72. 's ectric issued a written report describing the condition and corrective a,tions in accordance with 10CFR50.46 and 10CFR50.73 on August 13, 1992.

E . Attachment 2 provides a detailed description of the proposed change, the basis ~for the change, a safety analysis of the change, and TV Electric's determination that the proposed change does not involve a significant hazards consideration.

9209090249 920903 Af '

PDR ADOCK 05000445 Pt PDR moun sw La.st o.n u a n u m ot

- l(kf l

_e - - - . , .n

. nn-, r-, , , - - - . ~

l TXX 92323 Page 2 o'. 2 Attachment 3 provides the affected Technical Specification pages

( NUREG 1399), marked-up to reflect the proposed thange.

In accordance with 10CFR50.91(b). TV Electric is providing the State of Texas l with a copy of this proposed amendment.

TV Electric requests approval of the proposed amendment by August 31, 1993, with implementation to occur within thirty days af ter NRC approval.

Should you have any questions in this matter, please contact David Bize at (214) 812 8879.

Sincerely, William J. Cahill, Jr.

DNB/dnb Attachments: 1. Affidavit

2. Description and Assessment

3. Marked-up Technical Specification Page (NUREG-1399)

Enclosures:

1. Westinghouse letter, WPT-14670, 'TU Electric Company, Comanche Peak Steam Electric Station Unit Number 1, Small Break LOCA Using W-FLASH Peak Clad Temperature (PCT),'

July 13, 1992

2. Westinghouse letter, WPT-14387, 'TU Electric Company, Comanche Peak Steam Electric Station, Unit Number 2. Small Break LOCA ECCS Reanalysis (PCT)," February 26, 1992

3. Westinghouse Letter, WPT 14479 'TU Electric Company, Comanche Peak Steam Electric Station. Unit Number 1, NOTRUMP Small Break LOCA Analysis - Engineering Assessment in Support of Continued Operation,' July 13, 1992 c - Mr. J. L. Milhoan, Region IV Resident inspecter, CPSES (2)

Mr. T. A. Bergman, NRR Hr. D. K. Lacker Bureau of Radiation Control Texas Department of Public Health 1100 West 49th Street Austin, Texas 78704

i i

Attachment I to TXX 92323 Page 1 of I l

UNITED STATES OF AMER]CA tiUCLEAR REGULATORY COMMISSION in the Matter of )

)

Texas Utilities Electric Company ) Docket No. 50 445 l

) I (Comanche Peak Steam Electric ) l Station, Unit 1) ) i i

AFFIDAVIT W. J. Cahill, Jr. being duly sworn, hereby deposes and says that he is Executive Vice President, Nuclear of TV Electric, the lead Applicant herein; that he is duly authorized to sign and file with the Nuclear Regulatory Commission License Amendment Request 92+003 ' Replacement of the WFLASH Computer Code with the NOTRUMP Computer Code for the Small Break Loss of Coolant Accident (LOCA) Emergency Core Cooling System (ECCS) Evaluation Model,'

for the captioned facility; that he is familiar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge, information and belief.

W. J. Cahill . _V Executive Vi President. Nuclear STATE OF TEXA5 )

)

COUNTY OF DAMAS)

Subscribed and swore to before me, on this day of G 6[ ._u 1992.

-/

n 1 A SHARION HAMDRICK

,!

• Notary Puolic, S.ste of Toass Notary Public

1. 1. cuamium caos.. is et '

l 1

l i

1 t

i i

F b

f i

DESCRIPTION AND ASSESSMENT t

i,TTACHMENT 2 TO TXX 92323 f PAGE-1 0F 10 i

l t

?

h i

T

?

I

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

< e Attachment 2 to TXX 92323 Page 2 of 10 REPLACEMENT OF THE WFLASH COMPUTER CODE WITH THE NOTRUMP COMPUTER CODE FOR THE SMALL BREAK LOSS OF COOLANT ACCIDENT (LOCA)

EMERGENCY CORE COOLING SYSTEM (CCCS) EVALUATION MODEL

1. BACKGROUND The CPSES Unit 1 Small Break LOCA analysis described in the CPSES Final Safety Analysis Report (FSAR) Chapter 15.6.5 (Ref. [1]) was licensed using Westinghouse's 1975 Small Break LOCA evaluation model incorporating the WFLASH computer code. Currently. Westinghouse is using the 1985 Small Break LOCA evaluation model with the NOTRUMP computer code to perf orm new analyses and update existing analyses. The 1985 Small Break LOCA evaluation model with the NOTRUMP computer code was developed following Three Mile Island (THI) *n response to NUREG 0737 TMI Action Item !!.K.3.30 (Ref. [2]). This

- model, which incorporates a number of advanced features over-its -

predecessor, was developed to provide a more realistic Small Break LOCA simulation as required by the NRC. TV Electric participated as a member of-Westinghouse Owners Group inLthe development of the modified Small Break

' LOCA code NOTRUMP. NOTRUMP demonstrated compliance with Appendix K to 10CFR50 and the NRC issued a Safety Evaluation Report (SER) on May 21.-1985.

As: required by NUREG 0737 TMl Action item !!.K.3.31 (Ref. -[2]). plant-specific calculations with the models described in-TM1 Action Item II.K.3.30 must be' submitted to the NRC demonstrating compliance with 10CFR50.46. The NRC staff further indicated that this may be accomplished by generic

- analyses to demonstrate that the previously--NRC approved WFLASH Small Break LOCA results were-conservative when compared with the new NOTRUMP Small Dreak LOCA results.

The generic _results, documented in WCAP-11145 (Ref. [3]), demonstrated'that a plant . specific reenalysis of CPSES with the NOTRUMP Small Break LOCA should result in the calculation of a limiting Peak Cladding Temperature (PCT) which would be significantly-lower than that calculated by WFLASH r

y a u-, .,,,,,w h- g .-r+ 4.c-,--,r,.m-~n ,- 4 r w a ,,,.,wr 4 -w e p ,, , , ,,.,,m-- , ,, ,,,,..,,,p -- w e, w e r-,v v - - ,, -w

I

]

l l

Attachment 2 to TXX 92323 Page 3 of 10 j i

Small Break LOCA. It was therefore concluded that a plant specific  ;

I reanalysis using the 1985 Small Break LOCA evaluation model with the NOTRVHP '

computer was not needed to comply with TH! Action Item II.K.3.31 because the l WFLASH Small Break LOCA analyses results conservatively had shown compliance  ;

with 10CFR50,46. #

On July 13, 1992 -Westinghouse transmitted the results of a 10CFR50.59 safety' evaluation to TV Electric (Ref. [4) Enclosure 1). The safety evaluation was for an error in the portion of the CPSES Small Break LOCA 7

analysis which addresses fuel cladding burst and the resultant coolant channel blockage. -Correction of the error increased the Small Break LOCA I PCT over the 10CFR50.46 criteria of c200*F. TV Electric received the

. Westinghouse letter on July 14, 1992, and notified the NRC Operations Center via the-Emergency Notification System in accordance with 10CFR50.72.

TU~ Electric provided a written report, Licensee Event Report LER 92 018 00 *

(transmitted via TU Electric letter TXX 92371), which satisfied the reporting requirements of 10CFR50.46(a)(3) and 10CFR50.73, to the NRC on August 13. 1992.-

i TU Electric decided that the analysis of record should be changed to the more advanced 1985 Wentinghouse evaluation model with the NOTRUMP computer ,

code because Westinghouse was already using the 1985 evaluation model to periWrm new analyses or update existing analyses for other plants, the 1985 evaluation model code had previously received NRC approval for use at other plants, and the 1985 evaluation model had been- used in the .Small Break' LOCA analysis for CPSES Unit 2 (submitted.to the NRC for review in Ref. [5),

Enclosure 2).-

In-anticipation of changingfthe analysis of record and to' demonstrate continued compliance with 10CFR50.46. TV Electric had Westinghouse perform an analysis of CPSES Unit 1 for the limiting break size using the 1985 Small Break.LOCA evaluation model with the NOTRUMP_ computer code. A single break

-size was analyzed rather_than a break spectrum because a comparison between b

. - - - . - - . - ~ - - . - . - . . . - ~ . - - - . - - - . - .

-Attachment 2 to TXX 92323 Page 4 of 10 CPSES Unit 1 and CPSES Unit 2 demonstrated that the results of the break spectrum study for CPSES Unit 2 could be applied to CPSES Unit 1, The results of the analysis confirmed that CPSES Unit 1 continued to comply with -!

10CFR50.46.

11. DESCRIPTION Of TECHNICAL SPECIFICATION CHANGE RE0 VEST TV Electric is proposing to replace the 1975 Westinghouse Small Break LOCA

. evaluation model of record for CPSES Unit I with the 1985 Westinghouse Small Break LOCA evaluation model for the reasons discussed above. The proposed change revises the Small Break LOCA analytical method referenced in the  ;

Administrative Controls Section of.the Technical Specifications (Ref. (63).

Specifically, in section 6.9.1.6 of the Technical Specifications the changes o deletes '

WCAP 8200, "WFLASH, A FORTRAN IV COMPUTER PROGRAM FOR SIMULATION Of i

TRANSIENTS IN A MULTI LOOP PWR,* Revision 2. June 1974 (H Proprietary). :(Methodology for Specification 3.2.2 - Heat -Flux Hot Channel Factor.), and ,

o adds WCAP 10079-P A, *HOTRUMP.- A N0DAL TRANS!ENT-SHALL BREAK AND GENERAL NETWORK CODE," August' 1985, (H Proprietary!. . ( Hethodology'for -

Specification 3.'2.2 Heat flux Hot Channel f actor. )

WCAP-10054 P A, ' WESTINGHOUSE SHALL ECCS F JALVATION MODEL USING THE

.N0 TRUMP CODE,' August 1985, (W Proprietark). (Hethodology for Specification 3.2.2 - Heat Flux Hot Channel factce.) _  !

WCAP 11145-P A,_' WESTINGHOUSE SHALL BREAK LOCA-ECCS EVALVATION MODEL GENERIC STUDY WITH THE NOTRUMP CODE, October 1986, (H Proprietary).

(Methodology. f or -Specification 3.2.2 Heat Flux Hot Channel Factor. )

. .. 1 l

Attachment 2 to TXX 92323 -l Page 5 of 10 The affected Technical Specification page. 6-25 has been marked to reflect these changes and has been provided as Attachment 3.

!!!. ANALYSIS l

The CPSES Unit 2 Small Break.LOCA analysis (Ref. [5]) has been perfomed

-with the NRC approved 1985 Small Break LOCA evaluation model and submitted to the NRC for review. The CPSES Unit 2 analysis included a break spectrum consisting of 2 . 3+ and 4 inch breaks. In Small Break LOCA, the thermal- {

hydraulic response is governed mainly by system parameters; the effect on the thermal-hydraulic response due to minor core dif ferences is less significant. The system parameters of the two units are very similar.

Table 1 is-a comparison'of the pertinent plant' system and design parameters of CPSES Unit 1 and Unit 2. As shown, the plant specific data for the two q plants are-almost identical. This similarity can also be applied to the break spectrum studies because the system response to the different break sizes would be similar. 'Due-to the similarity of the two units, the I

-limiting break size for Unit 2 would also be the limiting break size for Unit 1.

~ Based on the NOTRUMP Small Break LOCA analyses performed for CPSES Unit 2, 6-

, single Small Break LOCA analysis (Ref. [7], Enclosure 3) wLs performed for -

-. - r CPSES-Unit 1 using the NOTRUMP evaluation model. That is, the most limiting break identified in the CPSES Unit 2 analyses, the 3-inch cold leg break, '

was analyzed for CPSES Unit 1 with the changes necessary to model the CPSES Unit 1 core (17x17 standard fuel anj the D4 steam generator instead-of 17x17 optimized fuel and the model 05 steam generator). The PCT results for both e units are-shown in Table 2. Comparison of the CPSE! Jnit 1 and Unit 2

results for the~ 3-inch break show the dif ference in PCT is small as expected. - The results are well below the 2200'F limit set forth-in 100FR50.46.

L )

L

_. - _ _ _ ___._. _ _ . _ _ _ .. _ . _ _... . . _ _ _ _ _ _ _ -m _ _ _ _

Attachment 2 to TXX 92323 Page 6 of 10 lable 1 CPSES Unit 1 and Unit 2 Comparison Unit 1 Unit 2  ;

ilSSS Thermal Power (HWt) 3411+14 (RCPs) 3411+14 (RCPs)

Total Peaking Factor, F,. 2.32 2.32 Limiting Power Shape = Same (F5AR_ Fig. 15.6 48, Ref..(1])

Accumulator. Water Volume (f t') 850 850 Accumulator Gas Pressure (psia) 600 600 Safety injection Pumped Flow Same (FSAR Fig. 15.6 47, Ref. [1])

_ Initial Con _ditions-(loop flow. Same vessel inlet & outlet temps, reactor coolant pressure, steam generator pressure and tube p1'ugging levels)

Steam Generator Tube OD (in) _0.75 0.75  ;

Tube Thickness (in) 0.043 0.043 tio, of U tubes 4578 4570 lieat Transfer Area (f t') _ 48,'300 .48,165 Core Desion Fuel Array 17x17 17x17 Clad OD-(in) 0.374 0.360 Gap Gas' Pressure-(psig) 450 275 Clad Thickness (in) 0.0225 0.0225 l: ~ ~

E

l l

i i

l Attachment 2 to TXX 92323 Page 7 of 10  ;

Table 2 N01 RUMP Analysis Peak Cladding Temperature ('F) Comparisons Break Eltg Unit 1 Uni.t 2  :

2' 1005

• 3' 1418- 1434 4' 1291  ;

Although the NOTRUHP analysis was run for only one break size, a spectrum of breaks (2 inch and 4 inch) is not required for CPSES Unit 1. as previously discussed, because of the similarities of the two units. The break spectrum results for CPSES Unit 2 exhibit large differences in the calculated PCTs ,

between the 2 inch and 4 inch breaks when compared to the limiting 3 inch break. Due to plant similarities and the similar analysis results, the i trend of the break spectrum results for CPSES Unit 2 can be ,

applied to.the. analysis for CPSES Unit 1. The CPSES Unit 1 current licensed I analysis' of record Lsing the-less refined WFLASH computer code shows that

-the 4-inch cold leg break is limiting. The 3 inch cold-leg break reported in Ref. [7] using the more advanced NOTRUHP code has been shown to be limiting.for CPSES Unit 2 and traditionally _ analyses performed using the Westinghouse N01 RUMP code have shown smaller breaks to be more limiting when ,

compared to' analyses performed using the WFLASH code for the same-plant.  ;

~

The'CPSES' Unit 1 specific analysis using NOTRUMP results in a significantly lower PCT compared to the current PCT using the WFLASH code in the 1975 Small Break LOCA evaluation model. The revised analysis results meet the regulatory requirements set forth in 10CFR50,46.

'The plant conditions. prior to and after this amendment will remain  :

unaffected.

1 L

4 mg srm-'-pt=p-g- m-~-y yr m r,w'4 e +-We- em w-ige +mW6- 4 mh4==-

Attachment 2 to TXX-92323 Page 8lof 10 IV. BASIS FOR NO SIGNIFICANT HAZARDS DETERMINATION TV Electric has evaluated the no significant hazards consideration involved with the' proposed change in accordance with the three standards set forth in 10CFR50,92(c) as discussed:

Does the proposed change; (1) Involve a significant-_ increase in the probability or consequences of an accident previously evaluated?

The proposed change pertains to replacing the CPSES Unit 1 1975 Small Break LOCA evaluation model using WFLASH with Westinghouse's current 1985-Small Break LOCA evaluation model using the NOTRUMP code. There are no potential failure modes identified or hardware and process parameters affected by the proposed change. Selection of an updated evaluation model does not increase the probability or consequences of an event.

Thus, implementation-of this change does not increase the probability-or the consequences of-an accident previously analyzed.

(2) _ Create the possibility of a new or different kind of accident from any accident previously evaluated?

The evaluation model that is being changed determines the effectsoof a licensing basis accident._ Because this change ~only affects analysis methods, there are no new-failure modes or new types of accidents introduced as a result of this proposed change. There sre no previously deemed -incredible events being made credible.

Therefore, this change does not create'the possibility of an accident

-different from any_ accident evaluated in the licensing basis documents.

_?fy w a-ir e + D e -am"re--m-tws- re,-&---_+-e--,n -+ w+ n a t-eeVsv- w -vww r, - -e %M O M- tw eh.ia. saW

Attachment 2 to TXX-92323 Page 9 of 10 (3) Involve a significant reduction in the margin of safety?

The proposed change will not have any ef f ect on equipment perf ormance and availability. The analysis results must meet the regulatory requirements set forth in 10CFR50.46(b). The principle Small Breat LOCA result is the calculated PCT. Since the PCT remains under the 2200 F acceptance criteria, there is no increase in LOCA consequences. _

Therefore, the proposed change does not involve a significant reduction in the margin of safety.

Based on the above evaluations, TV Electric concludes that the above described change satisfy the no significant hazards consideration standards of 10CFR50.92(c) and, accordingly, a no significant hazards finding is justified.

V. ENVIRONMENTAL EVALUATION o p

As stated in Section IV(3), results satisfying he requirements of  ;

10CFR50.46 will pose no increase in LOCA consequences or a reduction in the I

margin of safety. Therefore, the environmental evaluation is excluded, j VI. REFERENCES

[1] CPSES Final Safety Analysis Report, Section 15.6.5, ' LOSS OF COOLANT ACCIDENTS RESULTING FROM A SPECTRUM OF POSTULATED P!P!NG BREAKS WITHIN THE REACTOR C00LAftT PRESSURE BOUNDARY.*

[2] CPSES Final Safety Analysis Report , Response to NUSEG 0737 THI Action items ll.K.3.30 and ll.K.3.31, pp. II.L-15 through ll.K-18.

_ _ _ . _ _ _ . _ _ _ .._._... _ _ _ q i

- Attachment 2 to TXX-92323 l

- Page_10..of 10 l

\! l l

[3] WCAP-11145 P A, '

WESTINGHOUSE SHALL BREAK LOCA ECCS EVALVATION H0 DEL GENERIC STUDY WITH THE NOTRUMP CODE." October 1986.

[4] Westinghouse letter, WPT 14670. 'CPSES UNIT-1 SHALL BREAK LOCA ECCS REANALYSIS USING NOTRUMP

• July 13. 1992. (Enclosure 1)

[5] Westinghouse Letter, WPT*14387,

• CPSES UNIT-2 SMALL DREAK LOCA ECCS REANALYSIS," February 26, 1992. (Enclosure 2)

[6] CPSCS Unit 1. Technical Specifications, Administrative Controls, Section 6.9.1.6. ,

[7] Westinghouse Letter, WPT 14479, 'CPSES UNIT +1 NOTRUMP SMALL BREAK l LOCA ANALYSIS ' ENGINEERING ASSESSMENT IN SUPPORT OF CONTINUED OPERATION," April 15. 1992. (Enclosure 3) 1 1

6

-+

k T

.,;m,.,......-e ,,w._,m,m.,y,w,,-_-r-_wr-m,..,.,, -pe n yy. w..-e-e m.y r- w .m.,r.,. -,,py,..v---=,