ML20012D037

Responds to Generic Ltr 89-19 Re Design of Steam Generator Overfill Protection.Util Does Not Plan to Implement Physical Mods or Administrative Changes Since Overfill Protection Sys Meets or Exceeds Guidance in Generic Ltr

ML20012D037
Person / Time
Site:	Summer
Issue date:	03/19/1990
From:	Bradham O SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-89-19, NUDOCS 9003260353
Download: ML20012D037 (3)

Text

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March 19, 1990 '

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l l Document Control Desk U. S. Nuclear Regulatory Commission i

Washington, D. C. 20555

Subject:

Virgil C. Summer Nuclear Station Docket No. 50/395  !

Operating. License No. NPF-12  !

Response to Generic Letter 89-19 Gentlemen:

l

Attached is the South Carolina Electric & Gas Company (SCE&G) response to Generic Letter 89-19 concerning the design of steam generator overfill protection. This response supports the conclusion that the Virgil C. Summer ,

Nuclear Station currently has in place a design and supporting administrative i control that meets or exceeds all of the guidance as prescribed by Generic i Letter 89-19.

1 I declare that the statements and matters' set forth herein are true and correct -

to the best of my knowledge, information and belief. '

If you have any questions, please call at your convenience. ,

l Very truly yours, l

f

0. S. Bradham

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DCH/0SB: led Attachment '

I c:- D. A. Nauman/0. W. Dixon, Jr./T. C. Nichols, Jr.

E. C. Roberts R. V. Tanner J. C. Snelson S. D. Ebneter R. L. Prevatte J. J. Hayes, Jr. -J. B.'Knotts, Jr.

General Managers NSRC C. A. Price NPCF.

R. B. Clary RTS (LTR890019)

K. E. Nooland File (815.14) 9003260353 900319 Ih ADOCK 05000395 PDR N P PDC 00 '?

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Attachment 1 to Document Control Desk letter March 19, 1990 Page 1 of 2  ;

i South Carolina Electric & Gas Company Response to Generic Letter 89-19 l

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l Generic Letter 89-19 provides guidance with respect to acceptable designs for .

, overfill protection systems currently existing in Westinghouse designed PWR i plants. This guidance establishes certain criteria for plants which ,

currently have an overfill protection system which is initiated on a 2-out-of-3 channel logic and is safety grade, but uses one of the three channels i for both control and protection (Enclosure 2. Item 2. Group I of Generic Letter 89-19). The criteria for acceptance are as follows: ',

1) The protection and control systems must be sufficiently separate to ensure:  ;

A) They are not powered from the same power source.

B) They are not located in the same cabinet.

C) They are not likely to both be affected by a fire.

2) The plant must have in place plant procedures and Technical Specifications that require periodic checks to verify operability of the protection system.

A review of the Virgil C. Summer Nuclear Station (VCSNS) confirms that its design is consistent with the above description. -Therefore, VCSNS will address the issue of meeting the criteria as described above.

Each protection channel and each control channel is powered from individually separate 1E power sources which are backed up by both battery and diesel i generated power. Each protection channel and each control channel is housed-in an individually separate cabinet. Physical separation between each of the protection channels is in full compliance with IEEE-279 requirements.

• Separation between the protection channels and the control channels is through a IE qualified isolation device and meets circuit separation requirements of IEEE-279. The separation of each channel into individual cabinets, the routing of circuits in compliance with IEEE-279 and each channel having individually separate power sources assures the actuation of the overfill protection system will occur in the event of a fire.

A common-mode failure that results in a main feedwater pump trip is explained to be acceptable in Enclosure 2 of Generic Letter 89-19. The overfill protection system at VCSNS is not designed to prevent a common-mode failure; however, should a common-mode failure occur, the failure would ultimately e result in a Feedwater Isolation. It is important to note that both the protection and control cabinets are located in a common room which is environmentally controlled by redundant trains of ventilation. The ventilation systems are designed as safety-grade systems and meet single t

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• , Attachment I to Document Control Desk Letter March 19, 1990 Page 2 of 2 failure criteria. For this reason, the loss of ventilation is not a credible concern. .

The overfill protection circuitry is a part of the Reactor Protection System and, as such, is addressed in Technical Specification 3/4.3.2, " Engineered Safety Feature Actuation System Instrumentation," Functional Unit 5. " Turbine .

Trip and feedwater Isolation." As a requirement of this specification, plant  !

procedures are in place that verify the operability of the overfill protection circuitry as follows:

1) A Channel Check is performed each shift.

2) A Channel Calibration is performed every 18 months.

3) An Analog Channel Operational Test is performed monthly.

4) An Actuation Logic Test is performed monthly. a

5) A Master Relay Test is performed monthly.

6) A Slave Relay Test is performed quarterly.

7) An Engineered Safety Response Time Test is performed every 18 months.

In conclusion, for the reasons explained above, the steam generator overfill protection system at VCSNS meets or exceeds the guidance given in Generic Letter 89-19; therefore, VCSNS does not anticipate implementing any physical modifications or administrative changes in response to Generic Letter 89-19.

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