ML20106G058

Interim Significant Const Deficiency Rept 118 Re Plant Protection Sys (Pps)/Plant Monitoring Computer Interface. Initially Reported on 840928.Plug-in Connectors at PPS Disconnected,Tagged & Logged

ML20106G058
Person / Time
Site:	Waterford
Issue date:	10/17/1984
From:	Cook K LOUISIANA POWER & LIGHT CO.
To:	Knighton G Office of Nuclear Reactor Regulation
References
118, W3P84-2891, W3P84-2894, NUDOCS 8410310021
Download: ML20106G058 (2)

Text

.

9' Louissama ,4a o -o~oe .mee7 .

P O W E R & L 1 G H T ! New onteANa LouSMNA m80xeoo.

70174-8008 . (504) 3ee-a345 MIDDLE SOUTH UTluTIES SYSTEM October 17, 1984 W3P84-2891 3-A1.01.04 3-C41 Director of Nuclear Reactor Regulation Attention: Mr. G. W. Knighton, Chief Licensing Branch No. 3 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Knighton:

Subj ect: Waterford 3 SES Docket No. 50-382 Meeting with NRC Staff October 11, 1984

Reference:

Significant Construction Deficiency No. 118

" Plant Protection System (PPS)/ Plant Monitoring Computer (PMC)

Interface" This letter is to confirm discussions held during the subject meeting, and to document our position regarding actions in resolving the referenced 10CFR50.55(e) deficiency (SCD-118) which was reported by LP&L to the NRC on September 28, 1984.

In response to a requast by the NRC staff for a detailed discussion on SCD-118, members of LP&L, Ebasco Services, and Combustion Engineering met with NRC staff personnel on October 11, 1984. A description of the details of SCD-118 was given with special note made that the condition or failure mode never actually h.s.pened (there was no event), and the condition was discovered by plant technicians while troubleshooting a different problem in a related circuit.

The problem is related to only those analog setpoint signals generated in the Plant Protection System (PPS), and in particular only to those process measurements with two dropping resistors in the transmitters current loop. For Waterford 3 this is steam generator (SG) 1 & 2 Level, SG 1 & 2 Pressure, and Containment Pressure for each of four protection channels. Since the failure mode connects the common together effectively altering only one of the setpoint signals, the result is conservative for all but the contair. ment pressure reactor trip signal.

O g a

>: g o

Mr.'.G. W. Knighton W3P84-2891~

Page 2

- Our analysis of other common mode failures, including-complete fusion of the computer input cabinet, shows that the. tying-together of the commons and connecting then to ground-does not compromise or effect-the PPS function other than for the above two-dropping resistcrs circuits.

Immediate corrective action has been to disconnect, tag, and log the plug-in connectors at the PFS for the five setpoint signals discussed above. We have obtained concurrence from both Ebasco and CE that the'removall of these inputs

.from the plant computer is acceptable, and this action satisfies all isolation Concerns.

We believe that.we have comprehensively explained the details of SCD-118 to .the staff and are available to discuss it further if you require.

Very truly yours, K.W. Cook Nuclear Support & Licensing Manager KWC:RVS:GEW:sms cc: E.L. Blake, W.M. Stevenson, J.T. Collins, D.M. Crutchfield, J.H. Wilson, G.L. Constable, T.A. Flippo, G. Holahan, J.T. Beard, J.P. Joyce l

J f

l l

l I

(

. ._. . . .- . ._ . _ _ _ _ -_.