TXX-4134, Comments on Containment Sump Isolation Valves & Recommendations Made in Cygna Independent Assessment Program Rept Re Cable Tray Supports & Anchor Bolt Embedment Lengths. Std Set of Instructions for Supports Expected by 840501
| ML20087P243 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 04/02/1984 |
| From: | Schmidt H TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | Youngblood B Office of Nuclear Reactor Regulation |
| References | |
| TXX-4134, NUDOCS 8404060193 | |
| Download: ML20087P243 (4) | |
Text
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TEXAS UTILITIES GENERATING COMPANY Log # TXX-4134 File # 10010 surw4r rowen..oo xourn ouve ruxx1, o.a. ui. nuus,1xum,no, April 2, 1984 Mr. B. J. Youngblood Chief, Licensing Branch No. 1 Division of Licensing U. S. Nuclear. Regulatory Coninission Washington, D.C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION INDEPENDENT ASSESSMENT PROGRAM PERFORMED BY CYGNA
Dear Mr. Youngblood:
Texas Utilities has reviewed your concern regarding the containment sump isolation valves and the two recommendations made in the CYGNA IAP Report regarding:
(1) that a standard instruction be prepared for the design, revision and review of cable tray supports and, (2) that the anchor bolt embedment lengths be deleted from the support drawing.
In addition, Texas Utilities is presently reviewing the CYGNA IAP Report and any formal comments will be submitted to the NRC Staff and to CYGNA in the near future.
Containment Sump Isolation Valves The NRC Staff requested that Texas Utilities review the control and interlock mechanisms of the containment sump isolation valves (1-8811A/B).
In the CYGNA IAP Report Appendix H, Checklist Number EE-02 reviews the control circuitry of the containment sump isolation valves for compliance to FSAR Chapter 7.
Although the valve 1-8811B is not directly interlocked _to a RCS pressure setpoint of 425 psig, CYGNA indicates that such and interlock exists.
During the injection mode, the RWST/RHR pump suction isolation valves are open and allow flow to the RCS.
These valves can only be opened if the containment sump isolation valves are closed. The containment sump isolation valves open automatically.when two of four refueling water storage tank level signals are i
less than the 10-10-1 level setpoint, coincident with an engineered safety feature actuation signal (S signal). Furthermore, the design allows for automatic switchover from the ECCS injection mode to the recirculation mode during an accident. Operator action is required to close RWST/RHR pump suction
' isolation valves 8812A/B immediately following the opening of the containment sump isolation valves (cold leg recirculation mode).
In addition, the containment sump isolation valves must be closed before the RHR system can be aligned to the RCS hot leg during a normal cooldown.
The RCS pressure must be below approximately 425 psig before the RHR isolation valves will open.
Thus, the containment sump isolation valves are interlocked so that they must be closed before the following valves can be opened:
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B. J.-Youngblood Page 2~
- 1. ~ RWST/RHR pump suction isolation valves (8812A/B);
2.
RHR inner or: outer-isolation valves 8701A, 8701B, 8702A and 87028.
(below 364 psig RCS pressure setpoint) r
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FSAR Section 7.6.2.1 describes the control logic of the inner and outer RHR
-isolation valves (8702A/B and 8701A/B). These valves are normally closed and can only be opened after the RCS pressure is reduced below approximately 425 psig and the. containment sump isolation valves are closed.. Additionally, the RHR system ic only used for conditions below approximately 425 psig and 3500F.
Thus, the design of the RHR. system precludes the exposure to high pressure.
- The CYGNA comment regarding a direct interlock between the containment sump isolation. valve and RC pressure is not clear and should be clarified or reworded.
The design of the control-and interlock circuitry for the recirculation sump _ isolation -valves, RHR isolation valves and RWST/RHR pump suction isolation valves is correct and there is not a 425 psig RCS pressure permissive required to open the recirculation sump isolation valves.
Standard Iristructions - Cable Tray Supports A standard set of bstructions for the design, revisions.and review of cable tray supports as suggestad by CYGNA is being prepared and will be provided to CYGNA prior to May 1.
Anchor Bolt Embedment Lengths 4
-CYGNA suggested that anchor bolt embedment. lengths should be removed from pipe support drawings.
This. suggestion.was made to ensure that there would be no confusion between the embedment length.shown on the drawing and the embedment length used for design calculations.
Installation procedure CEI-20 (Rev. 9,12/16/83), " Installation of 'Hilti' Drilled-in Bolts" requires that anchor bolts be embedded to a minimum depth i
below the surface of the 4000 psi (28-day strength) structural concrete prior to setting. (torquing). A table in the procedure provides the anchor bolt diameter and the minimum embedment length for Hilti-Kwik and Super Kwik-Bolts.
(The minimum embedment length is approximately 41 times the diameter of the bolt for Kwik-Bolts and 61 times the diameter of the bolt for Super Kwik-Bolts).
The instruction has-been revised to state that the minimum embedment length shall be that specified in the anchor bolt installation procedure and that specified on the drawing.
Quality control procedures ensure compliance to these instructions.
Original design calculations to ensure adequate qualification of the anchor bolt design assumes-the minimm anchor bolt embedment lengths required based'on the CEI-20 procedure.
If, for an initial calculation, a greater embedment depth is necessary than required by the CEI-20 procedure, the required depth is indicated on the design drawing..
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B.LJ. Youngblood LPage 3 4.
Furthermore, if for any reason (re-analysis, "as-built" verification, etc.)
loads -are high and a deeper snbedment length is necessary than provided by the initial calculation using the minimum snbedment lengths in' the CEI-20 procedure
-or on the design drawing, then a calculation can be made to determine the Eminimum installed embedment length based on the actual bolt -length. This calculation.is done by knowing the actual-length of the bolt and subtracting the' Lthickness of the concrete topping (if any), steel plates, washers, and assuming the nut is-fully torqued.at the bottom of the threaded run of the bolt.
This provides a conservative estimate of.the installed enbedment depth. This depth can then be used in load calculations to determine the adequacy of the pipe
~ support design.
The engineer can also have a field verification made to determine the actual snbedment _ depth, if necessary.
Although the design support drawings and Installation Procedure CEI-20 provides a minimum enbedment length required, the design calculations can be based on a i
conservative estimate of the actual embedment length.
Therefore, there may be differences between the drawing minimum embedment length and the snbedment
-length used in the calculations, but, as CYGNA rightly states, the differences has no design impact. We feel that no further changes are required.
Summary Texas. Utilities will provide formal comments regarding the CYGNA IAP Report.
In addition, a standard set of instructions for cable tray support design, review and revision will be provided to CYGNA prior to May 1.
If there are any questions regarding the remaining concerns or those discussed above, please contact us.
Very truly yours, H. C. Schmidt 4
Manager, Nuclear Services i
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COMANCHE PEAK-.
s Mr. M. D. Spence!
President
- Texas ' Utilities-Generating Company.
400 N. Olive, L.B. 81
~ Dallas, TX 75201
- cc
- Nicholas S. Reynolds, Esq..
Mr. James E. Cummins Bishop, Liberman, Cook, Resident Inspector / Comanche Peak
-Purcell & Reynolds-Nuclear Power Station
'1200 Seventeenth St., N.W.
c/o U. S. Nuclear Regulatory Washington, D.C.
20036.
Commission P. O. Box 38 Robert A. Woodridge, Esq.
Glen Rose, Texas 76043 Worsham, Forsythe, Sampels &
-Wooldridge Mr. John T. Collins
~2001 Bryan' Tower; Suite 2500 U. S. NRC, Region IV Dallas, TX 75201 611 Ryan Plaza Drive Suite 1000 Mr. Homer C. Schmidt Arlington, TX 76011 Manager,' Nuclear Services Texas Utilities Generating Company Mr. Lanny Alan Sinkin Skyway Tower - 400 N. Olive St., L.B. 81 114 W. 7th, Suite 220 Dallas, TX 75201' Austin, TX 78701
.Mr. H. R. Rock B. R. Clements Gibbs and Hill,:Inc.~
Vice President Nuclear 393 Seventh Avenue Texas Utilities Generating Co.
New York, NY.10001 Skyway Tower 400 N. Olive St., L. B. 81 Mr. A. T. Parker Dallas, TX 75201 Westinghouse Electric Corporation
- P. O. Box 355 William Burchetta, Esq.
Pittsburgh, Pennsylvania 15230*
Law Office of_Northcutt Ely Watergate 600 Building IDavid J. Priester
' Washington, D.C.
20037 Assistant Attorney General Environmental Protection. Division Ms. Billie Garde
_;P. O.'_ Box 12548, Capitol Station Government Accountability Project Austin, TX 78711 1901 Q Street, N.W.
Washington, D.C.
20009 Mrs. Juanita Ellis, President
- Citizens Association for Sound Ms. Nancy H. Williams Energy CYGNA
_1426 South Polk-101~ California Street
' Dallas, TX 75224 San Francisco, CA 94111-5894
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