ML20101C272

Submits Addl Info Discussed During 960311 Telcon Re Modifying Main Steamline Tunnel Automatic Isolations

ML20101C272
Person / Time
Site:	LaSalle
Issue date:	03/11/1996
From:	Benes G COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9603180163
Download: ML20101C272 (2)

Text

,

Comnuinu ralth Idivin Company I

, l a%dle Generating Station

. 501 North 21st Hoad

• Marstdirm. II,613 il-9757 l Tel H15 357476i

, March 11,1996 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

Subject:

LaSalle County Nuclear Power Station Units 1 and 2 Submittal of Additional Information discussed during the March 11, 1996 Conference Call Regarding Modifying the Main Steamline Tunnel Automatic Isolations NRC Docket Nos. 50-373 and 50-374

References:

(a) G. Benes letter to U. S. NRC, dated January 18,1996, LaSalle Submittal Regarding Main Steamline Tunnel Leak Detection Isolations (b) G. Benes letter to U. S. NRC, dated March 1,1996, Comed

, Response to NRC Staff Request for Additional Information Reference (a) provided LaSalle Station's proposal for revising the Technical Specification requirements for the Main Steamline Tunnel Automatic Isolations.

Reference (b) provided ComEds Response to the NRC staff request for additional information. The purpose of this letter is to provide additional information that was discussed during a conference call between the NRR Project Manager and Comed on March 11,1996.

The engineering calculation, NED-I-EIC-0208, " Main Steam Tunnel Temperature Isolation Setpoint Error Analysis", included with the Reference (b) submittal, was prepared in accordance with the Comed's setpoint error analysis methodology.

This methodology is documented in Comed Technical Information Documents, TID-E/I&C-10, " Analysis ofInstrument channel Setpoint Error and Instrument Loop Accuracy" and TID-E/I&C-20, " Basis for Analysis ofInstrument Channel Setpoint Error & Loop Accuracy". This methodology is consistent with ISA Standard 67.04-1988, "Setpoints for Safety Related Instruments in Nuclear Power Plants" which provides an acceptable method of analysis as described in RG1.105,

" Instrument Setpoint for Safety-Related Systems".

l The Comed setpoint methodology does not deviate from nor require Comed to take any exceptions to RG1.105. The Comed methodology was previously reviewed during the Systems Based Instrumentation and Control Inspection (SBICI) performed at Comed's Dresden Nuclear Power Stations, August / September 1994. The inspection results, provided in report numbers 50-237/94016(DRS) and 50-249/94016(DRS)" concluded that the methodology was kAnla'JaSa!!eimsidt3.wpf I

9603180163 960311 ADOCK 05000373

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USNRC (2) March 11,1996 technically sound, consistent with current industry practices, such as ISA 67.04-1988, and sufficiently comprehensive for their intended purpose."

The Technical Specification amendment request is for the Leak Detection system l Group I isolation logic. This circuitry will remain on AC power supplies, as -

l currently configured. The Reactor Building Ventilation system isolation logic is l l

being changed to 125 VDC power to reduce the possibility of system isolations due  !

to loss of power. This change to the power supplies is not being installed until  ;

l L2R07/L1R08 (the first outage begins in September of 1996).

LaSalle has a reliable 125 volt DC distribution system. The Division 1 and Division 2 batteries each consist of 58 lead-calcium cells rated at 1200 amp-hours  !

for an 8-hour discharge rate at 77* F. The Division 3 battery consists of 58  ;

lead-calcium cells rated at 330 amp-hours for an 8-hour discharge rate at 77 F.

These batteries are Gould batteries and consist of rectangular cells with plates that are vertically oriented within the cells. This type of cell construction has ,

, been used in the Nuclear industry for approximately 20 years, with a history of l l

acceptable reliability. l l The 125 volt batteries at LaSalle were replaced within the past 5 years due to I

aging, and for additional capacity to support the current plant configuration. The i batteries have performed well since then, with one isolated cell failure (internal l short). The failed cell was discovered during quarterly surveillance testing of the 125 volt DC batteries. This failure represents less than a 0.03% failure rate. The failed cell was replaced immediately.

l The original Significant Hazards Consideration, that was included in the l Reference (a) submittal, remains valid.

If there are any further questions, please contact this oflice.

l l Sincerely, h/S W i Gary" . Benes Nuclear Licensing Adminintrator cc: H. J. Miller, Regional Administrator - RIII M. D. Lynch, Project Manager - NRR

. P. G. Brochman, Senior Resident Inspector - LaSalle l Office of Nuclear Facility Safety - IDNS i

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