ML20154M138
| ML20154M138 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 10/15/1998 |
| From: | Terry C, Walker R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TXX-98222, NUDOCS 9810200180 | |
| Download: ML20154M138 (3) | |
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' Log # TXX-98222
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File # 10010 C
C 902.5 (clo)
-1UELECTRIC October 15,1998 c.14.c w rry Senior Mce President
& PrincipalNuclear OBicer.
U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)- UNITS 1 & 2 DOCKET NOS. 50-445 AND 50-446
' RESPONSE TO INSPECTION ITEMS REGARDING THE CPSES SAFE SHUTDOWN IMPOUNDMENT DAM REF:
1)
NRC Letter from Timothy.J. Polich to C. Lance Terry, dated April 16,1998 Gentlemen:
On May 5,1997, an inspection was conducted at the CPSES ' Safe Shutdown impoundment Dam. On April 16,1998, the NRC transmitted a Federal Energy Regulatory Commission E
(FERC) inspection report to TU Electric (Reference 1). The NRC requested a written response i
to four action items identified in the FERC report. TU Electric's response to the four action items is provided in Attachment 1.
This communication contains new commitments regarding CPSES Units 1 and 2 as identified in
' Attachment 2.
If you have any questions, please contact Mr. Carl B. Corbin at (254) 897-0121.
Sincerely, 8.9. Q ll C. L. Terry 9810200180 981015 0
By:
M' A
f A N 0500 g 5 i Roger M. Walker hd b
Regulatory Affairs Manager
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Attachments c-Mr. E. Merschoff, Region IV Mr. J. I. Tapia, Region IV (clo)
Mr. T. J. Polich, NRR Resident inspectors, CPSES CoMANCllE PEAK STEAM ELECTRIC STATION P.O. Hox 1002 Glen Rose. Texas 76043 1002
, to TXX-98222 5
- F ags 1 of 1 Item 1 NRC/ Federal Energy Regulatory Commission (FERC) Report Finding:
j "Ah th'e s'urface rock on the outer shells of the SSID [ Safe Shutdown impoundment Dam] deteriorates, new rock should be evaluated for durability and be sized for fetch
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and wave run up determined from updated design criteria."
t TU Electric Response:
The existing inspection procedure requires us to examine the rock slopes regularly for benching, rock degradation and slope stability. In the future when it becomes necessary to replace the dam riprap or surface rock, engineering will have to evaluate the new replacement rock since the original rock was quarried from quarries that are now under water. The design criteria for the outer shell surface rock (riprap) will also be re-evaluated.
Item 2 NRC/FERC Report Finding:
I "Piezometers should be tested and evaluated as to the cause of the readings above reservoir levels."
TU Electric Response:
TU Electric has consulted with Freese and Nichols (F&N), the original architect-engineer for the SSI. F&N has reviewed the piezometer readings and has determined the readings were suspect. F&N has reviewed the design basis for SSI and verified that, even with the worst case of accuracy for these instruments, the structural integrity of the dam is intact.
j However, in order to optimize the usability of the existing SSI Dam instrumentation, CPSES is in the process of conducting additional piezometer testing in accordance with guidelines from F&N. This testing is needed to identify the cause of the observed inconsistency and
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to determine what, if any, action / correction factors would be required to obtain the 1
appropriate consistency.
Item 3 NRC/FERC Report Finding:
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" Survey base monuments should be checked to ensure the accuracy of the data."
i TU Electric Response:
The SSI Dam base monuments have been checked for accuracy and were found acceptable.
i Item 4 NRC/ Federal Energy Regulatory Commission (FERC) Report Finding:
" Lastly, the licensee should inspect and / or survey the slopes underwater to ensure the quality of the outer shells of the SSID."
TU Electric Response:
l To determine if there was a problem with benching below the waterline, TU Electric requested the Texas Water Development Board Hydrologic Monitoring Section to take computer controlled, satellite-located depth readings along the underwater slope of both sides of the dam during the course of their 1997 sedimentation survey (completed after the FERC inspection). The results of the survey indicate a uniform underwater slope. In addition, the CPSES will visually verify the slope uniformity with underwater divers. This will be done during the next Service Water intako Channel Sedimentation Inspection (currently scheduled in 1998).
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4ttachm:nt 2 to TXX-98222
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,i Page 1 of 1 This communication contains the following commitments which are one-time actions:
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,CDF Number Commitment 27.163 In the future when it becomes necessary to replace the dam riprap or surface rock, engineering will evaluate the new replacement rock since the original rock was quarried from quarries that are now under water. The iz design criteria for the outer shell surface rock (riprap) will also be re-
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evaluated.
l 27164 Conduct additional piezometer testing in accordance with guidelines from i
Freese and Nichols (F&N). This testing will determine what, if any, action correction factors would be required to obtain the appropriate piezometer
. consistency, h
27165 Visually verify the safe shutdown impoundment dam slope uniformity with underwater divers. This will be done during the next Service Water intake Channel Sedimentation inspection (currently scheduled during 1998).
I The CDF (Commitment Data Form) number is used by TU Electric for internal tracking of CPSES commitments.
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