TXX-4556, Forwards Update of Results of Util Evaluation of Design Review/Quality Revalidation Recommendations Re Maint & Surveillance Activities Associated W/Tdi Diesel Generators & Provides Clarification Concerning Several Rept Components

Forwards Update of Results of Util Evaluation of Design Review/Quality Revalidation Recommendations Re Maint & Surveillance Activities Associated W/Tdi Diesel Generators & Provides Clarification Concerning Several Rept Components

ML20133K232
Person / Time
Site:	Comanche Peak
Issue date:	10/14/1985
From:	Counsil W TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	Noonan V NRC - COMANCHE PEAK PROJECT (TECHNICAL REVIEW TEAM)
References
TXX-4556, NUDOCS 8510210131
Download: ML20133K232 (9)

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Log # TXX-4556 TEXAS UTILITIES GENERATING COMPANY File # 10010 RKirWAY TOWER

• 400 NOR118 OtJVE frrREET. I.B. 5 &

• DALLAN. TEXAM 7830E i

WILLIAM G. COUNSIL EXECUTrwE WCE P#EusDEast Director of Nuclear Reactor _ Regulation

, Attention: Mr. Vince S. Noonan,. Director Comanche Peak Project Division of Licensing

.U. S. Nuclear Regulatory Commission Washington, D.C. 20555 l

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET N0. 50-445 DESIGN REVIEW / QUALITY REVALIDATION (DR/QR)

PROGRAM AUDIT FOR THE CPSES DIESEL GENERATORS REF: J. W. Beck letter TXX-4501 to V. S. Noonan dated June 27, 1985

Dear Mr. Noonan:

On July 1 and 2, 1985, an audit was performed at CPSES by the NRC concerning the Design Review / Quality Revalidation (DR/QR) _ efforts for TDI diesel generators. The results of the audit were favorable in that agreement was reached by all participants on the methods for successful resolution of all audit items.

The attachment to this letter, previously sent to the NRC by the referenced letter,.provides an update of the results of Texas Utilities' evaluation of the CPSES DR/QR recommendations regarding maintenance and surveillance activities associated with the TDI diesel generators. Changes discussed during the audit in regard to the maintenance and surveillance activities are reflected in this update.

In addition to the above, further clarification is provided below concerning several DR/QR report components: *

1. Engine Driven Fuel Oil Pump (Component 02-445) - The DR/QR report states "al> of the seal failures to date at Comanche Peak occurred during startup when there was the greatest probability of foreign matter getting between the seal faces and causing damage and leakage".

As a clarification, seal leakage on both Unit 1 engines occurred only j during plant startup testing.

2. Main Bearing Shells (Component 02-3108) - Concerning the main bearing upper placement shell for Train B engine, number 10, the DR/QR report states "this bearing is 0.0003 inches over the TDI specified thickness, but the clearance for the bearing is still within the TDI 8510210131 851014 5I DR ADOCK 050 s osvssson or rxxAs trrst.trass ns.scrasc contPANY

recommend:d clearance range, and is not censidered detrimental to engine operation". As a clarification, this component was addressed

.by Failure Analysis Associates in their report SP-84-6-ll(b) of.

6/11/84, " Evaluation of Main Bearing Shells at Comanche Peak", thereby providing the basis for the Owners' Group conclusion that the main bearing shells at CPSES are acceptable for their intended use.

3. Full Flow Lube Oil Filter (Component 02-820F) - The DR/QR report references the use of a full flow lube oil filter at CPSES with a particle retention size of 10 microns. In regard to the above, CPSES mechanical maintenance work orders C850002134 and C850002136 dated 7/24/85 document the installation of these filters for both engines.

Very truly yours, T

W. G. Counsil RWH/grr Attachment

Attachment to TXX-4556 dated October 14, 1985 4

Results of Texas Utilities' Evaluation of the CPSES DR/QR

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Recommendatio_nsRegardinika~in'tenanceandSurveillanceActivities Texas Utilities concurs with all Owners' Group recommended maintenance and surveillance activities as stated in the revised CPSES OR/QR component reports and revised maintenance matrix, with the following '

proposed modifications and/or clarifications:  !

1) Component F-068, Intercoolers Item 2 in the revised maintenance matrix recodimends cleaning and inspection of intercooler shell and tube sides after every refueling outage. Texas Utilities concurs with the inspection interval for the tube side, however, it is proposed that the shell side be comparably inspected at a five (5) year interval, based on a lack of identified problem experience for the shell side.

2) Component MP-022/23 Turbochargers Item 2 in the revised maintenance matrix recommends cleaning of the turbocharger impeller and diffuser at every refueling outage.

Texas Utilities proposes as a more practical maintenance approach that the impellers and diffusers be inspected every refueling outage and cleaned if necessary.

A supplementary Phase I report on turbocharger nozzle ring assemblies has also been issued by the Owners Group (Reference 1) l which contains the following additional Utility recommendations:

, a. At any turbocharger disassembly there should be a visual inspection of nozzle ring components for any apparent damage, failure or apparent mispositioning of vanes.

Replace all affected nozzle ring components. During reassembly ensure that capscrews are properly installed with recommended pretorque,

b. Monitor engine operation to ensure exhaust gas temperatures do not exceed those specified.

Texas Utilities will comply with the utility recommendation a) above during all turbocharger disassemblies and will perform pre-turbine exhaust temperature monitoring on a monthly basis.

3) Component 00-420, Lube Oil Pressure Regulating Valve Item 1 in the revised maintenance matrix recommends valve disassembly and cleaning at every outage. Texas Utilities concurs, but proposes that the interval be changed based on satisfactory industry experience with this valve. The valves for one engine will be disassembled, cleaned and inspected during the ,

first refueling outage. If no problems are identified, valve maintenance for each engine will be performed on an alternate refueling outage frequency.

4) Component 02-3078, Lube Oil Fittings, Internal Texas Utilities concurs with the recommendation in Item 1 to check tubing for dents or crimps at every refueling outage, however, this will be performed on accessible tubing only.

5) Component 02-310A u _ank, Cr shaft Item 2 in the revised maintenance matrix recommends that all crank journal diameters be measured at alternate outages. Texas Utilities proposes that a sample of main journals be measured at alternate refueling outages in order to be compatible with the established sampling frequency for the main bearing shells (see component 02-3108). TDI is in agreement with this proposal in their letter VTG-85041 of July 26, 1985.

6) Component 02-3108, Main Bearing Shells Item 1 in the revised maintenance matrix recommends visual and dimensional inspection of all main bearing shells for evidence of wear or misalignment at the first refueling outage and at alternate outages thereaf ter. Texas Utilities believes that the minimal problems encountered with the CPSES Unit 1 DG main bearing shells do not warrant inspection to the degree recommended by the Owners' Group. This' position is in agreement with the assessment by NRC and PNL of CPSES main bearing shell experience, as stated on pages 5.12 and 5.13 of PNL-5234 (enclosure to Reference 2). As l recommended by NRC and PNL, Texas Utilities will perform a sample inspection of two (2) highly loaded bearings per engine (bearings 5 and 6) at alternate refueling outages. Associated caps and saddles will also be checked. The need for additional inspection will be determined by the results of the initial sample inspection. Due to accessibility restrictions, inspection of bearings 1, 9, and 10 are to be performed only during an engine teardown (every 5 years). TDI is in agreement with this proposal in their letter VTG-85041 of July 26, 1985.

7) Component 0_2_-310C, Thrust Bearing Ring Item 2 in the revised maintenance matrix recommends a visual inspection of the thrust bearing for signs of wear or degradation concurrently with visual and dimensional main bearing shell inspections as recommended above. However, the main bearing shell inspection frequency has been modified as stated above. Texas Utilities proposes that the recommended visual inspection would be adequate if performed at a five (5) year interval (i.e., at overhauls) since a " bump check" for thrust bearing clearance will be performed at every refueling outage.

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'8 ) Component 02-315A, Cylinder Blocks Item 1 in the revised maintenance matrix recommends a visual inspection of the cylinder block and eddy-current inspection for stud-to-stud cracks between cylinder heads and for cracks between the block edge and studs at the block ends. The recommended frequency for the inspection is prior to returning the engine to standby service after any period of operation above 50% load.

Texas Utilities agrees that surveillance of the block top surfaces to ensure the absence of stud-to-stud cracks z.nd stud-to-edge cracks is appropriate for the first cycle of operation at CPSES Unit 1, until such time as the indications found on Train A, cylinders 4R and SR and on Train B, cylinders 1R and 4R are reinspected at the first refueling outage, fature inspection requirements should be based on the results of the above inspections and on any additional information provided by the Owners' Group. This position is in agreement with PNL's position in PNL-5234. Texas Utilities proposes at this time, however, that a visual and boroscopic examination be substituted for the eddy-current technique at the same frequency of performance. Texas Utilities believes that the use of visual /boroscopic examination will result in greater engine availability and is justifiable based on the stated conservatism in the Owners' Group assessment of the CPSES block indications as " ligament cracke" and on the absence of Widmanstaetten graphite in the CPSES cylinder blocks.

The indications in the Train A right bank cylinder block are the largest found at CPSES, but the Owners' Group has concluded that they were casting induced not service induced. The smaller indications in the Train B right bank cylinder block were also determined to be casting defects (by TUGCO) and are less than 0.050 inches in depth. All of these indications are in lower stress regions of the block top than ligament cracks and are all smaller than ligament cracks.

Widmanstaetten graphite is a degenerate microstructure that reduces the strength and fatigue resistance of grey cast iron.

The Owners' Group has determined that there is no Widmanstaetten graphite present in the CPSES Unit 1 cylinder blocks.

The Owners' Group has stated in the latest Phase I report (Reference 3) that blocks which have or are assumed to have l ligament cracks and which have no Widmanstaetten graphite are capable of withstanding a LOOP /LOCA event with sufficient margin, provided no stud-to-stud or stud-to-edge cracks exist.

Furthermore, engines with such cracks can still be returned to standby service provided these cracks are less than li inches in depth from the block top. Because initiation of stud-to-stud or stud-to-end cracks occurs at the block top surface and because they propagate downward, visual surface inspection of the block top will be adequate to assure the absence of such cracks.

As required in Reference 2, Texas Utilities will also perform l routine daily visual inspections of the block and external f

surfacts during op:; rating psriods, with a more thorough monthly inspection under strong lighting (also with the engine operating).

As stated above, block indications are to be reinspected for propagation at the first refueling outage.

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To ensure engine availability after surveillance testing above 50%

load, Texas Utilities will maintain the engine in standby service and perform the required surface inspection of the block top within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

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9) Component 02-340A, Connecting Rods CPSES is in agreement with the revised DR/QR report.

3 10) Component 02-3408, Connecting Rod Bearing Shells CPSES is in agreement with the revised DR/QR report.

I 11) Component 02-341A, Pistons ,

CPSES is in agreement with the revised DR/QR report.

12) Component 02-350A,_C_am Shaft Assembly, CPSES is in agreement with the revised DR/QR report.

13) Component 02-380A, Exhaust Manifold Item I in the revised maintenance matrix recommends magnetic particle examination of a sample of circumferential pipe welds and corresponding heat affected zones at the first refueling outage and at alternate refueling outages thereafter.

l Texas Utilities proposes to visually examine all accessible welds at the frequency given above, instead of a sample.of magnetic particle tests. It is felt that this procedure would provide a more practical approach with broader weld inspection coverage.

14) Component 02-387A, Crankcase Vacuum Fan Item 1 in the revised maintenance matrix recommends cleaning and inspection of the fan at alternate outages. Texas Utilities proposes, as a more practical approach, that the fan be inspected at alternate refueling outages with cleaning as necessary.

15) Component _ 62-390E,_R,0ck_er, A_rrr. Bushings r Item 1 in the revised maintenance matrix recommends visual and dimensional inspection of intake rocker arm bushings at the outage which precedes 2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br /> of operation by at least the sum of expected hours of operation in a LOOP /LOCA plus the expected hours of operation between outages. Similarily, exhaust rocker arm ,

bushings are to be inspected before 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> and intermediate rocker arm bushings before 730 hours0.00845 days <br />0.203 hours <br />0.00121 weeks <br />2.77765e-4 months <br />.

Texas Utilities proposes to p:rform a visual inspection of all rocker arms at every refueling outage, with a visual and dimensional inspection of all rocker arm bushings every 5 years during overhaul.

16) Component 02_-410A, Overspeed Trip Governor CPSES is in agreement with the revised DR/QR report.

17) Component 02-410C, Overspeed Trip Drive Couplings Item 1 in the maintenance matrix recommends that the present L-110 Lovejoy couplings be replaced with new units at the next outage.

As a clarification, Texas Utilities does not intend to replace these couplings at the first refueling outage per the Owners Group recommendation because they were inspected and reinstalled per TDI Service Information Memorandum (SIM) 363 instructions prior to the Owners Group making their recommendations.

18) Component 02-413A, Governor Linkage As a clarification, Texas Utilities will install lockwire on all l fasteners designed for use with lockwire. Other locking hardware will be installed where specified.

19) Component 02-415A, Woodward Governor Recommended settings will be reviewed to ensure compatibility with the Texas Utilities grid system requirements, and may be adjusted accordingly.

20) Component 02-441B, Starting Air Strainer Item 4 in the revised maintenance matrix recommends that air start strainers be cleaned and inspected monthly. Fouling of these strainers is not expected because this portion of the system contains air which has been dried and filtered by the air dryer.

CPSES is in agreement with the revised DR/QR report. However, if no problems are identified by the first refueling outage, Texas Utilities proposes cleaning and inspecting the strainers every outage. Texas Utilities will continue to blowdown the starting air lines at the drip legs assembly daily, as recommended in the revised DR/QR report.

21) Component 02_-500C, Breakers & Con _ tac _t Blocks Item 3 in the revised maintenance matrix recommends that circuit breakers be trip-checked at each outage. Texas Utilities believes that breakers of the molded case type should not be tested at frequent intervals and proposes to perform this test every 5 years for this type of breaker. Other types of breakers would be tested at each refueling outage as recommended.  ;

'22) Components 02-525B, C, Barring 02vice Controls & Filter Because the barring device is not required during engine operation, the Owners' Group recommendations for the associated components may not necessarily be incorporated by Texas Utilities, but will be taken into consideration.

23) Component 02-717C, Jacket Water Piping, Couplings, Fittings, Orifices &'T-5 trainers The DR/QR component report recommends that flanges be torqued per the general torque tables in the TDI Instruction Manual. Texas Utilities flange torquing procedure provides for greater torque than the general torque tables and will provide adequate load transfer to attaching supports.

24) Component 02-717G, K, Lube Oil Valv_es ,and Fuel Oil Valve _s, CPSES is in agreement with the revised DR/QR report. However, as a clarification, Item 1 of the OG maintenance matrix corresponds to 02-717K and item 2 corresponds to 02-717G. Item 1 covers the valves (relief) addressed iri the component report.

25) Component 02-810E, Jacket Water Heaters The Owners' Group recommends in the revised maintenance matrix that the following be performed at each outage: 1) measure heater insulation resistance, 2) inspect and clean heater elements, and

3) check calibration and inspect thermostat. 'However, this recommendation appears to be arbitrary in that it is not based on either a design review or on adverse component experience according to the component report. Texas Utilities believes that the activities recommended above would be adequate if performed at alternate refueling outages and intends to implement that interval.

26) Component 02-820A, Lube Oil Sump Tank Heaters The Owners' Group recommends that heater insulation resistance be measured and that thermostats be checked and calibrated at every outage. Based on satisfactory experience with these heaters, however, Texas Utilities proposes that these activities be performed at alternate refueling outages. The heater elements will be inspected at every refueling outage in conjunction with the tank inspection, as recommended.

27) Component CP-10_2_, Generator Controls CPSES is in agreement with the revised DR/QR report. ,

. 'Tha DR/QR maintenance and surveillance activities recommended by the Owners' Group are to be incorporated into the CPSES Unit I diesel generator preventive maintenance and surveillance program, as modified and/or clarified above, as follows:

Monthly and daily surveillance and maintenance items are to be incorporated into the surveillance or maintenance programs prior to exceeding 5% power at CPSES Unit 1. Items based on number of engine starts or hours of operation, as well as 18 month surveillance items, are included in this category.

Surveillance and maintenance items which are to be accomplished on a refueling outage or longer basis will be incorporated into the appropriate programs prior to the first refueling outage.

It should be noted, however, that evolution of the maintenance and surveillance program can be expected to occur based on implementation feedback, inspection results and on additional input from NRC, the.

Owners' Group, TDI or other applicable sources. Also, variations in the methods of achieving the intent of the recommendations may be necessary upon implementation in order to provide a practical approach to maintenance. Finally, the TDI inspection and maintenance forms l referenced in the " Comments" section of the maintenance matrix may or may not be used in the performance of the recommended activities.

Maintenance instructions and procedures will specify which forms are to be used, if any, for a specified activity.

REFERENCES

1. Letter OGTP-591-N-48 to H. R. Denton from C. L. Ray, Jr. dated November 27, 1984.

2. Letter to M. D. Spence from B. J. Youngblood dated October 1, 1984.

3. Letter 0GTP-627-N-51 to H. R. Denton from C. L. Ray, Jr. dated December 11, 1984.

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