ML20091P124
| ML20091P124 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 01/24/1992 |
| From: | Chrzanowski D COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| REF-GTECI-048, REF-GTECI-049, REF-GTECI-NI, TASK-048, TASK-049, TASK-48, TASK-49, TASK-OR GL-91-11, NUDOCS 9201310235 | |
| Download: ML20091P124 (2) | |
Text
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a Crmm:nwealth Edis:n i
1400 Opus Place b '
Downers Grove. Illinois 00$15 January 24,1992 Dr. Thomas E. Murley, Director Office of Nuclear Roactor Rogulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Attn: Document Control Desk
Subject:
Commonwealtn Edison Rosponse to Generic Letter 91 11 for LaSalle County Station LaSalle Units 1 and 2, NRC Docket Numbers 50-373 and 50 347
]
Referenco:
Generic Letter 01 11, "Rosolution of Generic Issuos 48, LCOs for Class 1E Vital Instrument Buses, and 49, interlocks and LCOs for Class 1 E Tio Breakers",
dated July 18,1991,
Dear Dr. Murioy:
Generic letter 91 11 was issued as part of the resoluilon of Gonoric Issue 128, " Electrical Power Reliability". The Generic issues (Gl 48 and GI 49) addressed by this letter involvo vital AC buses and tie breakers. Specifical:y the Generic Letter recommends that nuclear plants ensure that procedures are in place that include time limitations and surveillance requirements for the following; vitalinstrument buses (VIBs), inverters to VIBs, and tio breakers that can connect redundant class 1E busos (AC or DC) at one unit or that can connect Class 1E buses between units at the same sito.
Commonwealth Edison (Ceco) has reviewed Generic Letter 91 11 and has determined that LaSalle County Station (LaSalle)is in compliance with the Letter's recorr$mondations, The following evaluates the Generic Letterissues against Laballe's Class 1E AC and DC electrical distribution system.
Ilme Llmitations.and_Su!YelllaDC0$_f0LVltadnStrum0Dt.Bu00s_(VlBS)_andJRVD!terS DLOthonOns!to Po. Wet. Sources tolhe YJBs At LaSalle, most AC/DC vitalInstrumon'ation and ESF logic are fed from Class 1 E 120/208 VAC/125 VDC distribution panels that are part of the Class 1E divisional distribution sptem.
The 1E distribution system is required to be operable and energized by Technical Specification LCO 3.8.2.1 and 3.8.2.3 with appropriate Allowed Outage Times and surveillances. The Class 1 E AC divlslons, controlled by 3.8.2.1, have an eight hour LCO, The Class 1E DC divisions, controlled by the 3.8.2.3 specification have a 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> LCO. Those buses cannot be cross tied to a redundant i
- division, L
l The Division 1 and 2 AC buses can be tied to the opposito unit Division 1 and 2 buses, respectively, on tho 4,16 KV level via Unit tle Breakers. Th!s arrangement is contrciled with LCOs, actions, and survolilances established by Technical Specification 3.8.2.1.
The 125 VDC Divisional buses can be cross tied on the respective division 125 VDC buses on the opposite unit. The 125 VDC bus crost "os are administratively controlled by Technical Specification 3.8.2.3 which limits the time that ;he r
e is allowed.
The remaining AC vitalinstrumentatle egned to be ' fall safo* and is fed from the Reactor Protection System (RPS) buses. Each t s (A and B) is fed by a motor generator through Safety Related Power Monitoring Assemblies,(PMAs).
Therefore, LaSailo's vitalinstrument buses moet the requirements of the Generic Lettor. j j A
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Dr. Thomas E. Murley January 24,1992 Time Llrnitations and Surveillances for Tio Breakets connecting Common Unit 1E Buses (AC or DC).
The Class 1E Divlslons 1 and 2 are the only busos on each unit that can be crosstled to other busos. Each bus has a bus tio breaker that connects it with a non class.1E bus, which is fod from the Unit Auxillery Transforrner (UAT). The associated Class 1E bus is fed by the System Auxiliary Transformer (SAT). The IE to non IE bus tio breakers automatically trip on undorvoltago and thus may be olther open or closed without violation of the singlo.falluto critoria. Proper breaker alignment is verified by Techalcal Specification survolitance at least once ovory sovon days por Technical Specification 4.8.2.1. Technical Specification 3.0.2.1 limits the time breakers can be misaligned by this required curveillanco, and propor alignment is controlled by procedoro.
Timo Limitations and Surveillance for_TI.e Breakers Connecting Unit 1 E Duses (AC or DC) Between Units.
Division 1 and 2 Class 1E busos each can be cross tied to respective Division 1 and 2 bue.e9 on the oppoe.ito unit via unit tio breakers (one por bus, two breakers in sorios). Thorn are appropriato interlocks and alarms associated with closing of the unit tio breakers and the busos and breakers and SATs are sized to provide the total auxillary power for ono unit plus the onginoorod safety featuros auxiliary power for the other unit. This meets the requirements of General Design Urltoria 17.
The 125 VDC distribution ystem breaker alignment is controlled by proceduto with verification of proper alignment required by Technical Specification 4.8.2.3.1 m ioast onco per sovon days. Tho 250 VDC distribution system broakor alignment is also controlled by proceduto with verification of propor alignment required by Technical Specification 4.7.3.d.1.a at least once por s9 von days. The DC cross tlo breakers (ono por bus, two breakers in series) are used for ground isolation and maintenance activitlos. This maintenance arrangement is considered by proceduro to be an abnormal breaker alignment and the appropriato Technical Specification Action statomonts are applied to limit tholt uso.
Based on the above information CECO concludos that LaSallo's Technical Specifications for AC and DC distribution systems provido controls that assure the recommendations of Genotic Letter 91 11 are mot.
To the best of knowledge and belief, tho statomonts contalncd in this document are true and correct. In sorne respect those statomonts are not 'ased on personal knowledge, but on information furnished by other CECO employees, con' ; tor employees, and consultants. Such information has been reviewed in accordanco with Company practico, and I believe it to be rollable.
If there are any questions of comments, plonso contact me at (700) 515 7282.
Sincerely, L]. g A -( x, David J. Cbrzanowski Nuclear Licent'no Administrator Genonc Issues cc:
A. Dort Davis, Regional AdminirtratoeRill B. Siegel, Project Manager-NRR R. Elliott, Project Engineer NRR Senior Resident inspector, LaSalle j
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