ML20235S827
| ML20235S827 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 02/24/1989 |
| From: | William Cahill TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20235S831 | List: |
| References | |
| TXX-89077, NUDOCS 8903080036 | |
| Download: ML20235S827 (6) | |
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Log # TXX-89077 File-# 909.5 j
10010 c1o 1UELECTRIC February 24, 1989
- Esecutive Vice President
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U. S. Nuclear Regulatory Commission Attn: Document ~ Control Desk Washington, D. C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)-
DOCKET NOS.-50-445'AND 50-446 STATUS OF THE CPSES DIESEL GENERATOR ACTION ITEMS REF:
1)
NUCLEAR REGULATORY COMMISSION ~(NRC) SAFETY EVALUATION REPORT ON THE OPERABILITY / RELIABILITY OF EMERGENCY DIESEL GENERATORS-MANUFACTURED BY TRANSAMERICA DeLAVAL, INC. (TDI),
DATED AUGUST 5, 1986 (ALSO ISSUED AS NUREG-1216) 2)
TV ELECTRIC LETTER TXX-6236, DATED FEBRUARY 13, 1987
' Gentlemen:
NUREG-1216 the' generic Safety Evaluation Report (SER) on.the operability / reliability'of emergency diesel generators manufactured by Transamerica Delaval, Inc. (TDI) (see reference 1) requests licensees that own TDI emergency diesel. generators to review the SER and respond to certain action ~ items. TV Electric provided the CPSES )lant specific response to NUREG-1216 by letter logged TXX-6236, dated Fe)ruary 13, 1987 (see reference 2).
The following information is provided to revise'the TV Electric response to certain of the action items and to provide a report on the' current status of-these items:
4.2 CPSES Revised Status:
TV Electric will inspect the bearings in accordance with Revision 2 of the Design Review / Quality Revalidation (DR/QR)
Appendix II Maintenance and Surveillance (M/S) program.
See item 4.4 below for discussion of lube oil analysis M/S program.
4.4 CPSES Revised Status:
TV Electric will perform monthly lube oil analysis, including spectrochemical and ferrographic analysis, as specified in Revision 2 of the DR/QR Appendix II M/S program, component 02-540A, " Lube Oil Sump Tank."
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Rbruary 24, 1989 Page 2 of 6-r 6.2 CPSES Revised Status:
The Owners Group recommendation for centerline bowing inspection was published after the reassembly of the CPSES Unit 1 engines.
Reference 1 indicates that excessive centerline bow in connecting rods would result in axial misalignment of journal bearings and skewing of bearing oil film pressure profile, with pressures being higher on the side where oil film thickness is reduced.
This would tend to cause uneven wear of connecting rod bearing shells.
The inspection of CPSES Unit I connecting rod bearing shells, however, revealed no indication of uneven wear.
Further, if there was excessive centerline bowing in a connecting rod, installation and operational difficulties would have been' encountered.. TV Electric will verify the Unit 1 connecting rod bow is within the Failure Analysis Associates (FaAA) recommended limit at the 10 year major engine overhaul which is the next scheduled major.
engine disassembly.
Connecting rod bow will be checked for the Unit 2 diesels prior to Unit 2 fuel load.
6.3.1 CPSEE Revised Status:
Eddy-current testing was performed in late 1987 on all of the connecting rod box threaded holes of both Unit 1 engines.
FaAA conducted the testing using their non-destructive examination (NDE) procedure NDE 11.15 Revision 1, " Eddy-current Inspection Procedure-Threaded Carbon Steel Holes." No recordable indications were found in any of the connecting rod threaded holes.
6.3.2 CPSES Revised Status:
The Unit 1 connecting rod bolts were inspected in late 1987 using a wet fluorescent Magnetic Test (MT) method.
Inspection criteria for bolt, washer and rod seating surface galling developed by TDI as a follow-up to their July 2, 1986 10CFR21 report on connecting rods was also utilized during this inspection. Washers were changed to electroless nickel plated type to reduce the possibility of galling based on TDI recommendations.
6.3.4 CPSES Revised Status:
TV Electric will verify that the contact between the rack teeth in all Unit i diesel connecting rods is no less than the manufacturers recommended contact by the first major engine disassembly.
Twenty five percent of the connecting rods in the Unit 1 engines will be checked at the one-time 5 year sample inspection with the remainder of the rods being inspected at the 10 year major engine overhaul.
The Unit 2 connecting rod rack teeth will be checked prior to Unit 7 fuel load.
TDI's manufacturing process for the rods includes lapping and blueing the rack teeth to ensure that a minimum of 75% surface area contact exists between the mating teeth.
This process is considered by the Owner's Group to be adequate for joint assembly.
MT and Penetration Test (PT) examinations of the rack teeth
TXX-89077-Frebruary 24, 1989 Page 3'of 6 contact surfaces were performed during the 1984 engine teardowns.
If there was either improper joint fit or inadequate bolt torque (joint clamping force), fretting would have shown up as an indication or been noted by the inspector as a visual observation.
No. indications or abnormalities are noted on the inspection reports. Quality Control personnel who performed the NDE have t
confirmed that if there had been surface fretting present or the rack teeth it would have been noted.
None of the inspectors recall any such surface abnormalities.
6.3.5 CPSES Revised Status:
TV Electric performed a dimensional verification of-the link rod to link pin locating dowels and counter bores.
Results of this ver.ification show that the dowels are not long enough to interfere with proper contact.(i.e., zero clearance) between the rods and pins when the bolt torque is applied.
Excessive dowel' length with respect to the counterbore was found to be the original cause of-past adverse experience with rod to pin clearances based on a 1980 10CFR21 report from TDI, service information memo (SIM) 349, and' the Owner's Group evaluation of the condition.
The above dimensional check adequately establishes resolution of this concern for CPSES Unit 1.
6.4 CPSES Revised Status:
Ultrasonic measurement of connecting rod bolt preload was performed in late'1987. Measurements of the bolts were taken using a Raymond bolt gauge (Ultrasonic Test device), both prior to installation and following torquing, to determine bolt elongation.
Bolt elongation and bolt torque are both used as verification that there is sufficient clamping force in the connecting rod joint.
9.1 CPSES Revised Status:
TV Electric concurs with the concern regarding the 4th order resonance of the crankshaft and has incorporated precautions into site procedures regarding operation of the engine below 440 rpm.
9.3 CPSES Revised Status:
TV Electric concurs and will evaluate the severity of any unbalanced operating condition.
The Owner's Group position on
" severe" imbalance is that one cylinder not firing is not " severe" but more than one cylinder not firing can be " severe", depending on which cylinders are not firing.
TV Electric procedures use "more than one cylinder not firing" as the criterion for judging whether there is severe imbalance.
Additionally operating procedures provided precautions that apply when the difference between the highest and lowest cylinder exhaust temperature exceeds 1500F. Any unbalanced condition evaluated as " severe" will be identified to the NRC for review prior to returning the engine to service.
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11.3 CPSES Revised Status:
TV Electric will inspect the CPSES engine blocks in accordance with Revision 2 of the DR/QR Appendix II M/S program, which incorporates the Owners Group clarifications.
Inspections will be performed using either a borescope or an eddy-current probe. The CPSES blocks do not currently have any stud-to-stud or stud-to-end cracks.
If any are discovered during scheduled inspections, the NRC Staff will be promptly informed and the engine will not be considered operable until the proposed disposition and/or corrective actions have been approved by the NRC Staff.
11.6 CPSES Revised Status:
TV. Electric will conduct cylinder block top inspections in accordance with the CPSES site NDE program.
This pro upon American Society of Mechanical Engineers (ASME) gram is based Section V and is consistent with Pacific National Laboratory's (PNL's) recommendations.
Specific acceptance criteria using ASME SA-613 have been incorporated into site procedures.
Additionally, TV Electric ensures that contractors' NDE procedures are consistent with the CPSES program prior to performance of any contracted inspection.
12.1 CPSES Revised Status:
The cylinder heads in the Unit 1 engines have been replaced with-new cylinder heads that were inspected by TDI or TV Electric using the recommended liquid penetrant, magnetic particle and ultrasonic inspection methods.
Future cylinder heads will be examined in
'this manner prior to release from.the vendor's shop.
12.2 CPSES Revised Response:
TV Electric will conduct cylinder head inspection in accordance with the CPSES site NDE program.
This program is based upon ASME Section V and is consistent with PNL's recommendations. Specific acceptance criteria using ASME SA-613 have been incorporated into site procedures.
Additionally, TV Electric ensures that contractors' NDE procedures are consistent with the CPSES program prior to performance of any contracted inspection.
12.3 CPSES Revised Status The cylinder heads at r' 3ES were inspected in late 1987 for plug welds in the fuel injection nozzle bore area by FaAA.
Those heads identified as having plug welds were returned to the manufacturer and either repaired using a newer, NRC accepted technique (see NUREG-1216, Section 2.1.3.13) or scrapped.
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F;bruary 24, 1989 Pag:> 5 of 6-13.1 CPSES' Revised Status The studs were replaced with the latest design and installed in accordance with procedures recommended by TOI.
For the Train B diesel, no documentation exists for the installation of the head stud to engine lock washer or lubrication of the stud to block threads.
TDI informed TV Electric that the stud end would be 2-3 threads below the nut if the lock washer was missing.
This-condition does not exist on the Train B studs which are visible
'(half of the studs are inside the rocker box cover). TDI also stated that installation of the stud could be performed dry or with lubrication.
Based upon the observation that the visible Train B studs exhibit characteristics which. indicate the presence of lock washers and the fact that lubrication of the studs is opt.ional, TV Electric concludes that the studs were installed in accordance with manufacturer's recommendations.
14.1 CPSES Revised Status For Unit 1 Train A, linear indications were noted on main bearings nos. 1, 3, and 9.
The indications on bearing nos. 1 and 9 were evaluated by the Owner's Group as acceptable mincr casting discontinuities.
Fracture mechanics analysis of the bearing saddles indicates that there is a factor of safety of 15.8 against growth and propagation.
(Reference FaAA calculation support package SP-84-6-7(b).)
Based on this large factor of safety and the fact that the CPSES engine bases have been found to be free of Widmanstaetten graphite, there is ample justification -for differing inspection of the indication on the number 3 main bearing for Unit I train A to every engine major overhaul.
14.2 CPSES Revised Status The engine bases of the CPSES Unit 1 Diesel Generators were checked for Widmanstaetten graphite in late 1987 using method 1 of the Owner's Group supplemental report for component 02-305A.
FaAA performed the evaluation and reported that the microstructure in both CPSES engine bases is typical for ASTM A48 CL-40 grey cast iron and that there was no evidence of degenerative microstructure (Widmanstaetten graphite).
17.1 CPSES Revised Status Piston skirt boss areas on all 32 type AE piston skirts received licuid penetrant inspections for mapping and evaluation of linear inc ications.
Linear indications exceeding the liquid penetrant inspection acceptance criteria were noted on piston skirts SR and 6R on Train A and on piston skirt 7L on Train B.
The Train A, SR and 6R indications were also eddy-current tested to more sharply
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',Page 6.of 6-7 determine. the depths of the indications.
The Train B, 7L-indication visibly extended through the boss lip.
Evaluations of-the indications.by both TDI-and the Owner's Group found thatithe indications in all-three piston skirts were located in portions of
.the piston skirt which serve no structural purpose.
The indications were therefore ground to within acceptance criteria and satisfactorily retested.with liquid penetrant prior to-installation.in the engines.
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.CPSES Revised Status'-
The modification.to the turbocharger lubrication system has been completed per the TDI recommendation specified as a follow-up to l
the 10 CFR 21 ' report of February '15,1984. TV Electric will also:
ll continue to use the full-flow auxiliary lube oil pump.to provide prelubrication of. the' turbocharger-prior to all phnned engine.
starts.
TV Electric intends. to allow for pre-lubrication of all planned
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engine starts and is currently-discussing this matter with the NRC technical' specification reviewers.
If approved,.TV Electric will-
' pre-lubricate all' planned engine starts.
Sincerely, William'J. Cahill, Jr.
MCP/ddm c-Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3) hm
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