ML20204H625
| ML20204H625 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 03/22/1999 |
| From: | Alexion T NRC (Affiliation Not Assigned) |
| To: | Cottle W HOUSTON LIGHTING & POWER CO. |
| References | |
| TAC-MA3519, TAC-MA3520, NUDOCS 9903290117 | |
| Download: ML20204H625 (5) | |
Text
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Mr. William Ti Cottis March 22, 1999 President and Chief Executive Officer STP Nuclear Operating Company South Texas Project Electric Generating Station i
P. O. Box 289 Wadsworth, Texas 77483
SUBJECT:
' REQUEST FOR ADDITIONAL INFORMATION ON PROPOSED AMENDMENT TO COLD OVERPRESSURE MITIGATION CURVES IN TECHNICAL SPECIFICATION FIGURE 3.4-4, SOUTH TEXAS PROJECT, UNITS 1 AND 2 (STP) (TAC NOS. MA3519 AND MA3520)
Dear Mr. Cottle:
The Nuclear Regulatory Commission staff is reviewing STP Nuclear Operating Company's j
(STPNOC's) August 31,1998, application on the above subject. This amendment is associated with the Replacement Steam Generator Project.
i Based on its review, the staff has determined that additional information is needed, as i
discussed in the enclosed request for additional Information (RAI). This request was discussed with Mr. Mark VanNoy of your staff on February 24,1999, and a mutually agreeable target date l
of a response to the RAI by April 19,1999, was established. The staff appreciates the efforts l
expended with respect to this matter.
Sincerely, l
ORIGINAL SIGNED BY:
Thomas W. Alexion, Project Manager Project Directorate IV-1 1
Division of Licensing Project Management Office of Nuclear Reactor Regulation
' Docket Nos. 50-498 and 50-499 l
Enclosure:
As stated cc w/ encl: See next page DISTRIBUTION:
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4,*****,d March 22, 1999 l
l Mr. William T. Cottle President and Chief Executive Officer STP Nuclear Operating Company South Texas Project Electric Generating Station P. O. Box 289 Wadsworth, Texas 77483
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION ON PROPOSED AMENDMENT TO COLD OVERPRESSURE MITIGATION CURVES IN TECHNICAL SPECIFICATION FIGURE 3.4-4, SOUTH TEXAS PROJECT, UNITS 1 AND 2 (STP) (TAC NOS. MA3519 AND MA3520)
Dear Mr. Cottle:
The Nuclear Regulatory Commission staff is reviewing UD Nuclear Operating Company's (STPNOC's) August 31,1998, application on the above subject. This amendment is associated with the Replacement Steam Generator Project.
Based on its review, the staff has determined that additional information is needed, as discussed in the enclosed request for additional information (RAI). This request was discussed with Mr. Mark VanNoy of your staff on February 24,1999, and a inutually agreeable target date of a response to the RAI by April 19,1999, was established. The staff appreciates the efforts expended with respect to this matter.
Sincerely, fWL Thomas W. Alexion, Project Manager Project Directorate IV-1 Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-498 and 50-499
Enclosure:
As stated -
cc w/ encl: See next page
'a +
Mr. William T. Cottle STP Nuclear Operating Company South Texas, Units 1 & 2 cc:
Mr. Cornelius F. O'Keefe Jack R. Newman, Esq.
Senior Resident inspector Morgan, Lewis & Bocklus U.S. Nuclear Regulatory Commission 1800 M Street, N.W.
P. O. Box 910.
Washington, DC 20036-5869 Bay City, TX 77414 Mr. T. H. Cloninger Vice President 4
A. Ramirez/C. M. Canady Engineering & Technical Services J
City of Austin STP Nuclear Operating Company 3
Electric Utility Department P. O. Box 289 721 Barton Springs Road Wadsworth,TX 77483 i
Austin, TX 78704 Office of the Govemor i
Mr. M. T. Hardt ATTN: John Howard, Director Mr. W. C. Gunst Environmenta! and Natural City Public Service Board Resources Policy P. O. Box 1771 P. O. Box 12428 San Antonio,TX 78296
'ustin, TX 78711 Mr. G. E. Vaughn/C. A. Johnson Jon C. Wood Central Power and Light Company Matthews & Branscomb P. O. Box 289 One Alamo Center Mall Code: N5012 106 S. St. Mary's Street, Suite 700 Wadsworth,TX 74483 San Antonio, TX 78205-3692 INPO Arthur C. Tate, Director Records Center Division of Compliance & Inspection 700 Galleria Parkway Bereau of Radiation Control Atlanta, GA 30339-3064 Texas Department of Health 1100 West 49th Street Regional Administrator, Region IV Austin, TX 78756 U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Jim Calloway Arlington,TX 76011 Public Utility Commission of Texas Electric Industry Analysis D. G. Tees /R. L. Balcom P. O. Box 13326 Houston Lighting & Power Co.
Austin, TX 78711-3326 P. O. Box 1700 Houston,TX 77251 Judge, Matagorda County Mategorda County Courthouse 1700 Seventh Street i
Bay City, TX 77414 1
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s Reauest for AdditionalInformation Cold Overoressure Mitiaatina System Curves for Reolacement Steam Generators South Texas Project. Units 1 and 2 l
1.
In your submittal of August 31,1998, you stated that the new Model A9i steam l
generator design results in an increase in the reactor coolant system (RCS) volume.
For the mass injection limited regions this is expected to have a relaxing effect on the cold overpressure mitigating system (COMS) setpoints. However, in your submittal you stated that the new setpoint curves for the A94 steam generators are more bounding than your existing curves. During a conference call on January 14,1999, you stated that while the increase in RCS volume had a relaxing effect on the setpoint, the increase in RCS flow as a result of the steam generator replacement had the opposite effect because of the increase in hydraulic pressure drop between the beltline region and the pressure instrument. Please provide a quantitative justification for your conclusion that the new curves for the new steam generators bound the existing cuwes in the mass injection limited regions. In your justification, please also include a discussion of the assumption for the amount of tubes plugged in the new analyses and the effects of this assumption.
2.
As described in your submittal of August 31,1998, your assumptions for the mass injection transients include flow from one charging pump with letdown isolated and the charging control valve in its normal position in WCAP-13782, the methodology referenced for determining the COMS power-operated relief valve (PORV) setpoints, the assumptions for the mass injection transients include the maximum deliverable flow from one centrifugal charging pump with letdown isolation and charging control valve fully open. In addition, WCAP-13782 includes Figures 2.1 and 2.3, which provide the maximum credible flow rates at a given pressure for the two cases analyzed (RCS temperature < 200 *F and RCS temperature 2 200 'F). There appears to be a discrepancy between the assumptions stated in your submittal dated August 31,1998, and the assumptions listed in WCAP-13782 with the assumptions listed in the WCAP being more conservative with respect to injection flow rates. Please address this apparent discrepancy and provide the flow rates used for the two cases (RCS temperature < 200 'F and RCS temperature 2 200 *F). Also, please provide a discussion of how this is conservative with respect to the mass injection analyses.
3.
In the August 31,1998, submittal you indicated that the proposed COMS setpoint curve (proposed TS Figure 3.4-4) considers overshoot and undershoot and valve stroke times.
Your submittal also indicated that pressure instrument uncertainty was not accounted for in the development of the proposed setpoint curve. Section 50.36(c)(2)(i) of 10 CFR defines limiting conditions for operation (LCOs) as the lowest functional capability of equipment required for safe operation of the facility. Section 50.36(c)(2)(ii)(C) requires LCOs for components that actuate to mitigate a design-basis transient that presents a challenge to the Integrity of a fission product barrier. Section 50.36(c)(3) requires Enclosure
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surveillance requirements for calibration of components to assure that the LCOs will be met. The pressure ! strument uncertainty in the COMS system, if not accounted for, can lead to a delay in the actuation of COMS, consequently causing system pressure to exceed the Appendix G pressure temperature limit. Therefore, in order to assure that
/ppendix G pressure temperature limits are not exceeded, instrument uncertainty must be accounted for. Please address this apparent deficiency.
4, in your mass addition analyses you did not account for injection from the safety injection accumulators. In addition, only one of the charging pumps was assumed to inject. The staff has reviewed your proposed technical specifications and could not find the corresponding restrictions to isolate the safety injection accumulators and to disable all but ono charging pump. Section 50.36(c)(2)(ii)(B) requires that an operating restriction that is an initial condition of a design-basis transient analysis that presents a challenge to the integrity of a fission product barrier be included in technica; specification LCOs.
Please address this apparent inconsistency.
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