ML20011E810

Final & Interim Deficiency Rept CP-90-001 Re Feedwater Isolation Valve (FWIV) Impact Testing.Initially Reported on 900116.Pressure & Temp Limitations Associated W/Fwiv Incorporated in Technical Requirements Manual,Rev 2

ML20011E810
Person / Time
Site:	Comanche Peak
Issue date:	02/07/1990
From:	William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CP-90-001, CP-90-1, TXX-90068, NUDOCS 9002220519
Download: ML20011E810 (3)

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' 4 4 1 FQ .- . Log- # TXX-90068

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-20010 .;

' ' 910 3 TUELECTRICl .Ref. # 10CFR50.55(e)  !

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February:7 -1990. F p <

- Wmism J. cahill, Jr. .l

Executive Vke he

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U.' S Nuclear Regulatory' Commission  ;

p . Attn:- Document Control-Desk '

.Washington.~D. C. 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET NOS. 50 445 AND 50-446 1 FEEDWATER ISOLATION VALVE IMPACT TESTING 1 SDAR:. CP-90-001 (FINAL REPORT - UNIT 1

' INTERIM REPORT - UNIT 2)-

j Ref: 1) .TV Electric Letter TXX-89748 From William J. Cahill, Jr, -t to U.S.N.R.C. Dated November 27, 1989

2)- TV Electric Letter TXX-90012 from W1111am'J. Cahill, Jr.  ;

to'U.S.N.R.C. Dated January 15, 1990

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3) TV Electric Letter TXX-90034 from William J. Cahill, Jr. *

.to U.S.N.R.C. Dated January 26, 1990 >

-Gentlemen: ,

On January.16, 1990 TV Electric verbally notified-the NRC.of'a potentially reportable: deficiency involving unverified assumptions, utilized.in a fracture '

mechanics analysis performed to demonstrate the acceptability of'ferritic-pressure retaining components of the Feedwater Isolation Valves (FWlV). After i

further evaluation TV Electric is conservatively reporting this deficiency .

-: pursuant to the provisions of 10CFR50.55(e), t

. Discussion -

1 The FWIV's are ASME Class 2 valves procured from Borg-Warner in accordance '

with CPSES Specification 2323-MS-208.1. ASHE Code (1974 edition, Winter '74 L addendum) -states that impact testing is. optional. ' It was invoked in-the t i

original purchase specification for these valves, but suissequently deleted, y

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-However,=as described in Reference 1, the CPSES Final Safety Analysis Report  ;

~ (FSAR) prior to Amendment.77 stated that ferritic materials in the Containment Pressure Boundary are impact resistance tested. This resulted in an

inconsistency with the specification.

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.TXX-90068' February 7 1990 i Page 2 of 3

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In lieu of impact-resistance testing TV Electric elected to change the FSAR i (Amendment 77)'and perform a fracture mechanics analysis to demonstrate  :

acceptability of the ferritic (SA-105 carbon steel forging) pressure retaining components of the FWlV's. This analysis was accomplished utilizing conservative assumptions for the FWlV material fracture toughness and maximum postulated flaw size. However, these assumptions were not verified to be  !

valid for the specific heats of material utilized in the FWIV's at CPSES.

, To confirm the fracture toughness assumption utilized ~in the fracture i mechanics analysis, samples were taken from the body,-neck and bonnet of a-Unit 2 FWlV manufactured from the same heat. numbers as the Unit I valves (with

, the exception of the valve body material on FWlV,1FW 0077). Testing of these L

Unit 2 samples confirmed that the material toughness values utilized in the L

analysis'were conservative. Examination of a material sample removed from the body of 1FW 0077 established the similarity of the microstructure and hardness in-this heat to that of the Unit 2 test specimens, and established that the samples exhibited the proper chemical composition for SA-105 carbon steel.

These examination.results, in conjunction with the Certified Material Test Report from the material supplier confirming that the material has acceptable tensile strength properties, provide reasonable assurance- that this heat would i exhibit a toughness similar to that of the Unit 2 samples.

Volumetric examination was performed on the bonnets of the Unit 1 FWIV's to

. provide additional confidence in the flaw size assumptions. This testing confirmed the conservative nature of the flaw size assumptions for the bonnet 1 material. Volumetric examination of the body / neck material was not considered -l practical due to valve body geometry. Because the flaw size assumptions were not completely confirmed for the valve body and neck material, TU Electric has conservatively elected to utilize the impact testing acceptance criteria of

-the ASME Code as additional guidance in establishing the acceptability of 1

-these parts. This has resulted-in establishing a FWIV lower service l temperature of 900F for the valve body and neck when exceeding 675 psig. As i discussed in Reference 3 a temperature of 400F was determined to be an acceptable lower service temperature for the bonnet material based on the .i information provided in CPSES Engineering Report ER-DBE-ME-045 (Feedwater  :

Isolation Valves Impact Testing and Analysis). For consistency with the valve body and neck, the pressure restriction of 675 psig at temperatures below- q~

900F will also.be observed for the bonnet.

This deficiency was potentially applicable to other ASME Class 2 or 3 Main Feed or Hain Steam valves (performing a containment isolation function) which were qualified for use by a fracture mechanics analysis. A review of specification requirements for applicable components has indicated only the FWIV's were affected.

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f TXX-90068

' February 7, 1090 Page 3 of 3 i Engineering Report ER 0BE-ME 045 supporting the conclusions provided above is

• available for your inspector's review,  ;

-Safety Sionificance The FWIV.'s-are relied upon to perform a containment isolation function during accident conditions. A conclusive verification of the flaw size assumptions used in the fracture mechanics analysis was determined _to be impractical and' therefore the possibility of existence of a condition adverse to the: safety .;

of plant' operations could not be conclusively eliminated. In addition, extensive evaluation was required to resolve this issue, therefore it is being conservatively reported pursuant to 10CFR50.55(e). ->

Corrective Action Pressure and temperature limitations associated with the FWlV's have been incorporated.in the Technical Requirements Manual Revision 2 (transmitted to the NRC per Reference 2), and appropriate operating procedures have been '!

changed to ensure compliance with the limit.

l, Resolution of this' issue for Unit 2 will be' accomplished prior to Unit 2 fuel:

load.

. Sincerely, William J. Cahill, Jr.

) 'l L By:

D. R. Woodlan Docket Licensing Manager CBC/daj c - Mr. R. O. Hartin, Region IV Resident Inspectors, CPSES (3)

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