ML20151U199

Responds to NRC 880714 Telcon Request for Addl Info Re Util Application for Amend to License NPF-68 Amending Tech Specs to Allow Operation W/Positive Moderator Temp Coefficient

ML20151U199
Person / Time
Site:	Vogtle
Issue date:	08/12/1988
From:	Hairston W GEORGIA POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20151U204	List: ML20151U199 ML20151W463
References
VL-22, NUDOCS 8808180446
Download: ML20151U199 (3)

Text

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Georg a Power Ccepany 333 Piedmont Avenue

, Attama.Georgta 30308 Telertone 404 52&C526 Maing Addrcrt post omce so, esas l At'ana. Georg's 30302 Nuclear Opeutions Depadrnent ' *N N C' t W" VL-22 1077m X7GJ17-Y600 August 12, 1988 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 PLANT V0GTLE - UNIT 1 NRC DOCKET 50-424 OPERATING LICENSE NPF-68 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION POSITIVE MODERATOR TEMPERATURE COEFFICIENT Gentlemen:

By letter dated May 19, 1988, Georgia Power Company (GPC) applied for an amendment to the Vogtle Unit 1 Technical Specifications to allow operation with a positive moderator temperature coef ficient. The NRC staff requested additional information concerning our application in a July 14, 1988 telephone call. The enclosures to this letter provide the requested information.

Please contact this office if you have any further questions.

Sincerely, W. , // S-I W. G. Hairston, III l Senior Vice President, Nuclear Operations JH:llh

Enclosures:

1. Responses to NRC Staff Questions

2. Revised Tech Spec Page B 3/4 9-1 c: U. S. Nuclear Regulatory Commission Dr. J. N. Grace, Regional Administrator Mr. J. B. Hopkins, Licensing Project Manager, NRR (2 copies)

Mr. J. F. Rogge, Senior Resident Inspector-Operators, Yogtle I

800 f

I G808180446 880812 8 i PDR ADOCK 03000424 1 P PDC >

GeorgiaPower A ENCLOSURE 1 PLANT V0GTLE - UNIT 1 NRC DOCKET 50-424 OPERATING LICENSE NPF-68 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION l POSITIVE MODERATOR TEMPERATURE COEFFICIENT l QUESTION 1: Are DNB figures available for the rod withdrawal from subcritical ,

and loss of normal feedwater events?  :

1 RESPONSE 1: For the rod withdrawal from subcritical analysis, the most limiting conditions during the transient are evaluated to confim that the DNB limit is met. DNBR versus time plots are not generated during this confirmation. This approach is consistent with the analysis currently presented in the FSAR.

DNBR versus time plots are not presented for loss of normal feedwater or loss of offsite power. With respect to DNB, the loss of nomal feedwater event is bounded by the loss of load / turbine trip analysis. The pertinent difference between these two events is that in a loss of normal feedwater the turbine trip is not assumed to occur until after reactor trip. This allows for continued heat removal (steam flow) which is a benefit.

Similarly, the loss of offsite power event is bounded by the complete loss of flow analysis. The coastdown in the loss of offsite power event does not occur until after reactor trip (the time of rod motion) which is less limiting. Therefore, the event is not analyzed for DNB concerns, but rather, for the long-term heat removal capability. This approach is consistent with the current FSAR analysis.

QUESTION 2: Figures 3.7-5 (pg. 3-60) suggests that there is water relief through the pressurizer PORVs. Please explain the apparent discrepancy between the text (pg. 3-11) and the figure.

RESPONSE 2: Figure 3.7-5 does show relief through the pressurizer PORVs at approximately 25 seconds. This mass relief, however, is steam.

This can be demonstrated by reviewing Figure 3.7-1 which plots pressurizer water volume versus time. It can pressurizer water volume is less than 1700 ft.geen

, while seen that th the Vogtle pressurizer volume is 1800 f t.J. Therefore, there is no water relief.

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mm

GeorgiaPower d ,

ENCLOSURE 1 (CONT'0)

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION POSITIVE MODERATOR TEMPERATURE COEFFICIENT QUESTION 3: P1 case explain RWST water volumes.

RESPONSE 3: o TS 3.1.2.5.b (Modes 5 & 6)

RWST contained volume: 70,832 gal . -> 99,404 gal . (PMTC) o TS 3.1.2.6.b (Modes 1-4)

RWST contained volume: 631,478 (no change) o BASES 3/4.1.2 (Modes 1-4) ,

RWST usable volume: 87,720 gal . -> 178,182 gal. (PMTC)

(Modes 5-6)

RWST usable volume: 12,630 gal . -> 41,202 gal . (PMTC)

NOTE:

Contained Volume = Usable volume + unusable volume Unusable Volume = tank volume not deliverable because of tank outlet location or instrument uncertainty Usable Volume = RWST volume deliverable to RCS, QUESTION 4: The revised PMTC wording of tech spec bases, 3/4.9.1, page 3/4 9-1 removes the "uncertainty allowance of 50 ppm".

Please explain, i RESPONSE 4: The revised text reflects the analysis assumption. The cycle specific analysis determines the required boron concentration to obtain a 0.95 shutdown margin. A conservative allowance of 109 ppm is then added to this calculated boron concentration. The adjusted 0.95 boron concentration (which includes the additional 100 ppm) is compared to the 2000 ppm boron concentration limit. The most restrictive value is then the value provided to demonstrate compliance with Tech Spec 3/4.9.1. A revised Technical Specification page B 3/4 9-1 clarifying the 100 ppm uncertainty allowance is enclosed.

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