ML20078G728

Application for Amends to Licenses NPF-87 & NPF-89,revising TSs Re Exclusion of Failures from Total Number of Failures Used to Determine Diesel Generator Test Frequency

ML20078G728
Person / Time
Site:	Comanche Peak
Issue date:	11/11/1994
From:	Terry C TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20078G729	List: ML20078G728 ML20078G736
References
TXX-94306, NUDOCS 9411160153
Download: ML20078G728 (9)

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Log # TXX 94306 M= File # 916 (3/4.8)

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Ref. # 10CFR50.90-Z C 10CFR50.36 1UELECTRIC C. Lance Terry a - g w ,r m a,ar November 11, 1994 l

U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

CGHANCHE PEAK STEAM ELEC TIC STATION (CPSES) 30CKET NOS. 50 445 AND 5C-446 SUBHITTAL OF LICENSE AMENDHENT REQUEST 94-017 EXCLUSION OF FAILURES FROM TOTAL NUMBER OF FAILURES USED TO DETERMINE DIESEL GENERATOR TEST FREQUENCY Gentlemen:

Pursuant to 10CFR50.90, TU Electric hereby requests an amendment to the CPSES Unit 1 Operating License (NPF-87) and CPSES Unit 2 Operating License (NPF-89) by incorporating the attached changes into the CPSES Units 1 and 2 Technical Specifications. These changes exclude the recent failures of the tubing for a vent valve off the fuel oil header for the Unit 2 Train B Diesel Generator from consideration in determining the Unit 2 Train B Diesel Generator test frequency. These changes affect CPSES Unit 2 only.

Attachment 1 is a required affidavit. Attachment 2 provides a detailed description of the proposed changes, a safety analysis of the proposed changes and TU Electric's determination that the proposed changes do not involve a significant hazard consideration. Attachment 3 provides the affected technical specification pages (NUREG 1468) marked-up to reflect the proposed changes. Also enclosed is a copy of Generic Letter 94 01, " Removal of Accelerated Testing and Special Reporting Requirements for Emergency Diesel Generators," May 31, 1994.

TU Electric requests that the License Amendment be approved on an expedited basis so that, if approved, the license amendment can be made effective as soon as possible.

c In accordance with 10CFR50.91(b), TU Electric is providing the State of Texas with a copy of this proposed amendment request.

9411160153 941111 PDR P

ADOCK 05000445 PDR 400 N. Ouve LB. 81 Da!!n.Texn 75201 0()I m

TXX-94306 Page 2 of 2 Should you have any questions, please contact Mr. Manu C. Patel at (214) 812-8298. .

1 Sincerely.

C. L. Terry By:_ ~ M Rogerf,0. Walker Regulatory Affairs Manager HCP/grp Attachments: 1. Affidavit

2. Description and Assessment

3. Affected Technical Specification pages (NUREG-1468) as revised by all approved license amendments

Enclosures:

1. Generic Letter 94-01, dated May 31, 1994

2. Applicable pages of Safety Evaluations. Inspection Requirements for TDI Diesel Generators (TAC No H85325).

March 17, 1994, c- Mr. L. J. Callan, Region IV Hr. T. J. Polich. NRR Hr. D. D. Chamberlain, Region IV Resident Inspectors, CPSES (2)

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

I Attachment 1 to TXX-94306 Page 1 of 1 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION

In the Matter of )

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1 Texas Utilities Electric Company ) Docket Nos. 50-445

) 50 446 (Comanche Peak Steam Electric )

Station, Units 1 & 2) )

AFFIDAVIT Roger D. Walker being duly sworn, hereby deposes and says that he is Regulatory Affairs Manager of TV Electric, that he is duly authorized to sign and file with the Nuclear Regulatory Commission this License Amendment Request 94 017; 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.

M Roger D" Walker Regulatory Affairs Manager STATE OF TEXAS )

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COUNTY OF DALLAS )

Subscribed and sworn to before me, a Notary Public, on this lith day of November , 1994. l 0t k - J

- Notar / Public l L

Gayle R. Peck

• Notuy Pubhc Sute of Texas My Comm. Expres 01/06/98 E ., >

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S ATTACHHENT 2 TO TXX 94306 DESCRIPTION AND ASSESSMENT l

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Attachment 2 to TXX 94306 Page 1 of 5 DESCRIPTION AND ASSESSMENT I, BACKGROUND The Comanche Peak Steam Electric Station (CPSES) design employs Emergency Diesel Generators (EDGs) to provide on site AC power in the event that off <

site AC power is not available. The EDGs are required to be tested on a periodic basis (normally monthly) to provide an ongoing demonstration of performance and reliability. In accordance with Technical Specifications, EDG failures are reported to the Nuclear Regulatorv Commission (NRC) in special reports, and when certain values for the , imber of failures per number of valid tests (as defined by Regulatory Position C.2.e of Regulatory Guide 1.108, Revision 1) are exceeded, the frequency of testing is accelerated to weekly.

The NRC Generic Safety Evaluation Report for TDI Diesel Generators, dated March 17, 1994, included as part of Generic Topical Report TDI-EDG 001-A (Reference 1), concluded that deletion of accelerated testing along with the addition of slow starting the EDGs decreases the wear and tear of the engines and increases the reliability and availability by reducing outage time. The data from engines in nuclear service which have implemented the slow start option support these conclusions. The technical specification i change covering the slow start of the EDGs was submitted to the NRC by LAR l 94 010 (TXX-94118, dated April 25, 1994) and has been approved by NRC as i License Amendment 29/15.

While the special reporting and accelerated testing program prescribed by Technical Specifications addresses EDG performance and reliability, implementation of the provisions of the maintenance rule for EDGs, including the applicable regulatory guidance, is an alternative program that provides desired flexibility, while maintaining necessary assurance of EDG reliability and availability. In Generic Letter 94-01 (Reference 2) the NRC concludes that such a program is an acceptable alternative to accelerated testing. Deletion of the special reporting and accelerated testing program was not included in the improved Standai j Technical Specifications, NUREG- '

1431 (Reference 3), which was issued prior to Generic Letter 94-01.

On October 31, 1994, the Unit 2 Train B Diesel Generator was in operation for testing. It had successfully completed a start and loading above 50% l for greater than one hour (one hour at 100% and two hours at 110%). During the run, a vent valve (1/4-inch) on the fuel header came free of the line it was attached to and fuel oil sprayed into the room. The diesel was shut down manually.

l An event had occurred previously at which time. the tubing which had failed was replaced with thicker tubing to make the line less susceptible to failure (see TXX 93430, dated January 14, 1994). The mode of failure is fatigue cracking which occurs due to the mass of a valve vibrating at the end of the tubing. This then stresses the rigid point of the tubing connection to the fuel piping causing failure. The tube that failed on the '

l Unit 2 Train B Diesel Generator is the only location that uses this configuration in a sent connection. The other such vent location on Unit 2

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. l Attachment 2 to TXX-94306 i Page 2 of 5 I has the vent valve connected directly to the tap off the fuel oil header and tubing is not used between the ta.p and the vent valve.

Surveillance Requirements (SRs) 4.8.1.1.2a and 4.8.1.2 require. in part, that each Diesel Generator be demonstrated OPERABLE (on a STAGGERED TEST l BASIS) in accordance with the frequency specified in Table 4.81. Table 1 4.81 requires, in part, that the frequency be increased from once per 31 days to once per 7 days if the number of failures in the last 20 valid tests is greater en or equal to 2. The seven day test frequency must be maintainec until seven consecutive failure free demands have occurred and the number of failures in the last 20 valid demands has been reduced to one.

TU Electric requests that the technical specifications be changed such that both failures on the Unit 2 Train B Diesel Generator caused by vent tubing failure be excluded from the total number of failures used to determine the Diesel Generator test frequency.

II. DESCRIPTION OF TECHNICAL SPECIFICATION CHANGE REQUEST On TS Table 4.8-1, the "*" footnote is being changed. The following phrase is to be added to the end of the first sentence in this footnote:

....except that the valid test failures of the Unit 2 Train 8 diesel generator identified on December 16, 1993, and October 31, 1994, may be excluded from the total number of failures used to determine the diesel generator test frequency.

This change excludes this failure from the total number of failures when determining test frequency.

III. ANALYSIS The functional requirement for the EDGs is to provide electric power for safe shutdown of the plant during loss of offsite power. To provide an ongoing demonstration of the reliability of the EDGs to fulfill this requirement, the EDGs are required to be tested on a periodic basis (normally monthly). In accordance with existing Technical Specifications, EDG failures are reported to the NRC in special reports, and when certain values for the number of failures per number of valid tests (as defined by Regulatory Position C.2.e of Regulatory Guide 1.108. Revision 1) are exceeded, the frequency of testing is accelerated to weekly.

Increased EDG testing does not equate to improved reliability. Each EDG start and operational cycle subjects the EDG components to stress and wear.

This, in turn, requires additional maintenance with out of service time.

Furthermore. each test start conducted when the EDG can be removed from service includes approximately two hours of unavailability while pre and post run checks are made to ensure that cylinder jacketwater has not entered

an engine cylinder. Therefore, deletion of prescribed accelerated testing will increase reliability by reducing engine wear and increase availability by reducing the time required for maintenance and the unavailability time associated with most test starts.

Attachment 2 to TXX 94306 Page 3 of 5 On October 31, 1994, the Unit 2 Train B Diesel Generator was in operation for testing. It had successfully completed a start and loading above 50%

for greater than one hour (one hour at 100% and two hours at 110%). During the run, a vent valve (1/4 inch) on the fuel header came free of the line it was attached to and fuel oil sprayed into the room. The diesel was shut down manually.

An event had occurred previously, at which time, the tubing which had failed was replaced with thicker tubing to make the line less susceptible to failure (see TXX 93430, dated January 14, 1994). The mode of failure is fatigue cracking which occurs due to the mass of a valve vibrating at the end of the tubing. This then stresses the rigid point of the tubing connection to the fuel piping causing failure. The tube that failed on the Unit 2 Train B Diesel Generator is the only location that uses this configuration in a vent connection. The other such vent location on Unit 2 has the vent valve connected directly to the tap off the fuel oil header and tubing is not used between the tap and the vent valve.

The intent of these Surveillance Requirements, in part, is to identify events that result in unsuccessful runs of the diesel generator to identify when additional actions are appropriate to assure the reliability of the diesel generators. The ultimate goal is to assure a reliable diesel generator - a diesel generator that can perform its safety function when called upon to do so.

The vent valve that caused the leak has been removed from the line and the line has been capped. This event will not recur on this machine. During the test of interest, the diesel generator performed properly in all other respects. Therefore, the failure mode is precluded from recurrence.

The accelerated testing schedule is inappropriate and would be counter to safety. Generic Letter 94 01, the NRC's SER for the Inspection Requirements for Transamerica Delaval Diesel Generators, and other documents have recognized the harmful impacts of excessive testing of these diesel generators. Excessive or unnecessary testing causes increased wear and degradation and contributes to reduced reliability. The accelerated Diesel Generator testing would provide no benefit as the failure mechanism which existed is no longer credible.

TU Electric has concluded that the granting of this license amendment has no negative safety impact and in accordance with Generic Letter 94 01, would avoid unnecessary testing which is detrimental to the Diesel Generator reliability.

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Attachment 2 to TXX-94306 Page 4 of 5 VI. SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION TV Electric has evaluated whether or not a significant hazards consideration is involved with the proposed changes by focusing on the three standards set forth in 10CFR50.92(c) as discussed below:

Do the proposed changes:

1) Involve a significant increase in the probability or consequences of an accident previously evaluated?

There are no initiating events in accidents previously evaluated that involve testing of EDGs. Therefore, deletion of accelerated testing of EDGs does not involve a significant increase in the probability of an accident previously evaluated.

A reduction in the number of test starts decreases EDG component stress and wear and decreases unavailability time for maintenance and pre and post run checks. The resulting change in EDG reliability and availability is an improvement toward ensuring the EDGs are capable of fulfilling their functional requirement to provide electric power for safe shutdown of the plant during loss of offsite power. The failure mode that caused the failures being excluded have been eliminated with the result that their impact on future reliability has likewise been eliminated. Therefore, deletion of accelerated testing of EDGs does not involve a significant increase in the consequences of an accident previously evaluated.

The end result of this technical specification change is to prevent unnecessary testing. As such, this action does not impact the probability of an accident. It only impacts the consequences of an I accident positively by eliminating unnecessary testing which could  !

reduce the reliability of the Diesel Generator; and therefore this -

Technical Specification change does not significantly increa.e the l probability or consequences of an accident.

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

The frequency at which EDG testing occurs does not affect the potential failure modes of the EDGs, which have already been assessed in the CPSES design. Therefore, a reduction in accelerated testing of EDGs does not create the possibility of a new or different kind of accident from any accident previously evaluated. .

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3) Involve a significant reduction in a margin of safety? I The margin of safety impact associated with accelerated testing relates to EDG reliability and availability. A reduction in the number of test  ;

starts decreases EDG component stress and wear and decreases unavailability time for maintenance and pre and post run checks. The resulting change in EDG reliability and availability is an improvement i i

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Attachment 2 to TXX-94306 Page 5 of 5 toward ensuring the EDGs are capable of fulfilling their functional requirement to provide electric power for safe shutdown of the plant during loss of offsite power. Therefore, a reduction in the accelerated testing of EDGs does not involve a significant reduction in a margin of safety.

Avoiding unnecessary testing has no impact on failure points and will reduce the likelihood of Diesel Generator failure when the engine is needed to perform a safety function. As a result, the requested technical specification change does not significantly reduce the margin of safety. This technical specification change does not constitute a significant hazards consideration.

Based on the above evaluations and the fact that these changes are consistent with Generic Letter 94 01 as issued by the NRC, TV Electric concludes that the activities associated with the proposed changes satisfy the no significant hazards consideration standards of 10CFR50.92(c) and accordingly, a no significant hazards consideration finding is justified.

V. ENVIRONMENTAL EVALUATION TV Electric has evaluated the proposed changes and has determined that the changes do not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released off site, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed changes meet the eligibility criterion for categorical exclusion set forth in 10CFR51.22(c)(9). Therefore, pursuant to 10CFR51.22(b), an environmental assessment of the proposed changes is not required.

VI. REFERENCES

1. Generic Topical Report TDI-EDG 001-A, " Basis for Hodification to ,

Inspection Requirements for Transamerica Delaval, Inc., Emergency Diesel Generators". April 28, 1994.

2, Generic Letter 94 01, " Removal of Accelerated Testing and Special Reporting Requirements for Emergency Diesel Generators". Hay 31, 1994.

3. NUREG-1431, " Standard Technical Specifications Westinghouse Plants",

Rev. O. September 28, 1992.

4. TV Electric letter logged TXX-93430 from William J. Cahill, Jr. to Mr. J. L. Hilhoan, USNRC dated January 14, 1994.

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