ML19325D490

LER 89-017-00:on 890914,discovered That Present Position of Transfer Switch for Power Supplying Control & Protection Relays for Diesel Generator Does Not Meet Requirements of App R.Caused by Inadequate procedures.W/891016 Ltr

ML19325D490
Person / Time
Site:	Prairie Island
Issue date:	10/16/1989
From:	Hunstad A, Parker T NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-017-01, LER-89-17-1, NUDOCS 8910240253
Download: ML19325D490 (6)

Text

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i 414 Nicollet Mall I Minneapohs, Minnesota 55401 1927 i Telephone (612) 330-5500 October 16,1989 10 CFR Part 50 Section 50.73 Director of Nuclear Reactor Regulation U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATINC PIANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR 60 Discovery That the Present Position of the Transfer Switch for Power Supplying Control and Protection Relays for D2 Diesel Cenerator Does Not Meet the Reauirements of Annendix R i

4 The Licenseo Event Report for this occurrence is attached.  ;-

Please contact us if you require additional information related to this event.

l l Thomas M Parker l

Manager Nuclear Support Services c: Regional Administrator Reglon III, NRC NRR Project Manager, NRC l Senior Resident Inspector, NRC MPCA Attn: Dr J V Ferman Attachment *

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68 Discovery That the Present Position of the Transfer Switch for Power Supplying Control and Protection Relays for D2 Diesel Generator Does Not Meet the Requirements of App. R tytNT Daf t ill Lem Nunesta son ARPORT Daf t (Te CTMen s ActLiTIES INv0Lvt0 tai

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An internal technical review of the plant 10 CFR 50 Appendix R design against the as-built configuration is being conducted. On September 14, 1989, this ,

review revealed that the normal control power to D2 Emergency Diesel Generator was supplied from 22 Battery instead of 12 Battery as described in the Safe Shutdown Analysis. One fire area exists containing normal control power cables for both D1 and D2 Diesel Generators, thus creating a condition that was out of compliance with the requirements of 10 CFR 50 Appendix R.

l The control power for D2 Diesel Generator was transferred to 12 Battery (the l

[ alternate or standby supply), thereby placing the plant back within its 10 CFR l

50 Appendix R design basis.

Administrative controls of the modification process in 1983 had not yet implemented the means to ensure incorporation of 10 CFR 50 Appendix R criteria

( into the design. This situation was rectified with the administrative control l

procedure revisions issued in 1984 The internal technical review is l continuing and will be completed to ensure that the as-built configuration is j in compliance with 10 CFR 50 Appendix R.

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0 ]O 0l2 or 0 l5 rixi ,,- a . w. . r=cs maunn EVENT DESCRIPTION On November 30, 1983, Design Change 82N505, DC CAPACITY AND DISTRIBUTION ADDITION was approved. D2 Emergency Diesel Generator Transfer Switch (EIIS Identifier JS) was installed by this design change on December 7,1983 (Se e Figure 1). The purpose of the transfer switch is to provide an alternate source of control power to D2 Emergency Diesel Generator (EIIS Identifier DG) during maintenance of the normal source. The Design Change 82N505 designated 22 Battery (EIIS Identifier BTRY) as the normal source and 12 Battery as the standby source for D2 Emergency Diesel Generator control circuitry. The original plant configuration had 12 Battery as the only source of control power.

During the process of identifying cables that require fire protection to be in compliance with 10 CFR 50 Appendix R, drawings which still showed the original configuration were utilized. On June 4,1984, Cable No. 2DCB 71 (EIIS Identifier CBLS) for D2 Emergency Diesel Generator Control Power from 125V DC Panel 22 Circuit 10 (EIIS Identifier PL), its source ultimately 22 Battery, to D2 Emergency Diesel Generator Transfer Switch (See Figure 1) was declared to l

be not a safe shutdown cable. On the same date, Cable No. 1DCB-83 for D2 l Emergency Diesel Generator Control Power from 125V DC Panel 12 Circuit 5, its l source ultimately 12 Battery, to D2 Emergency Diesel Generator Transfer Switch l

(See Figure 1) was declared to be a safe shutdown cabic.

l l These designations were just the reverse of what they should have been. These I

designations allowed Cable No. 2DCB 71, providing the normal supply of control power to D2 Emergency Diesel Generator to be not fire protected, although its i routing is through a fire area that also contains control power cabling to D1 l Emergency Diesel Generator. This is not in compliance with 10 CFR 50 Appendix R.

In order to assure that the as-built configuration of the plant met all the design assumptions that formed the basis for the Fire Hazards Analysis, an internal technical review was initiated. On September 14, 1989, the review disclosed the configuration discussed above.

Later in the day of September 14, 1989 the D2 Emergency Diesel Generator Transfer Switch was shifted to the Standby position (See Figure 1), thereby restoring the associated circuitry to compliance with 10 CFR 50 Appendix R.

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0 l0 0[3 or 0 l5 rum- . .c,mn. vim GAUSE OF THE EVENT The cause of the condition was the lack of adequate administrative control procedures over the modification process. Specifically, the modification l

process did not require the review of modifications for compliance with 10 CFR 50 Appendix R requirements at the time of the modification which changed the normal control power source to D2 Emergency Diesel Generator from 12 Battery to 22 Battery. The adn.inistrative control procedure which mandated that modifications be reviewed for 10 CFR 50 Appendix R considerations was first issued on July 6,1984. Additionally, at the time that the cables requiring fire protection were being identified, Design Change 82N505 was physically  ;

completed but the drawings had not been updated yet.

The determination of the cables requiring fire protection thus was made without knowledge of this  !

modification. On October 17, 1984, an administrative control procedure was issued which established the Construction Drawing Files. These files contain l marked-up drawings of modifications which have been made but for which the j drawings have not yet been revised. This procedure assures that a designer or i reviewer would have drawings available that accurately reflect as-built conditions even though the drawing revisions are not completed immediately after the modification is made.

ANALYSIS OF THE EVENT  ;

i With D2 Emergency Diesel Generator Transfer Switch in the Normal position, the unprotected control power cable 2DCB 71 for D2 Emergency Diesel Generator passes through Fire Areas 31 and 32. Therefore, a Design Basis Fire in either of these areas would disable D2 Emergency Diesel Generator No unprotected cables for D1 Emergency Diesel Generator are in Fire Area 31.

A Design Basis fire there could disable D2 Emergency Diesel Generator but D1 Emergency Diesel Generator would be available for shutdown from the control room, i

Unprotected control cable for D1 Emergency Diesel Generator passes through j Fire Area 32. A Design Basis Fire there could disable both Emergency Diesel '

Generators. Transient combustibles would have to be placed in a location well '

away from a normal traffic path or work area in order to cause this much damage.

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Prairle Island Unit 1 o[s;ololol2l8l2 8;9 0 l1 l7 0l0 0l4 or 0 l5 firi . e u.cw maaum Fire Area 32 is pan shaped in cross section. The bowl of the pan contains machinery and cables including 20 gallons of lubrication oil. The handle is a congested crawlspace containing cable and bus duct. This crawl space is 11 feet above the main floor and is 9 feet high. About nine feet of Cable No.

2DCB-71 is located in the crawl spaco 21 feet horizontally from the machinery area. Therefore, it is not possible for the installed lubrication oil to get close enough to Cable No. 2DCB 71 to cause damage to it.

The fire severity for Fire Area 32 has been designated "very light" in the Fire Hazards Analysis. Cable No. 2DCB-71 is installed in conduit. In practical terms, transient combustibles of sufficient quantity to cause damage through rigid metal conduit would have to be carried up 11 feet and over 21 feet through significant congestion in order to disable D2 Emergency Diesel Generator. This is highly implausible.

, During the period of time that this configuration existed, no fire occurred in Fire Area 32; thus there was no adverse effect on the health and safety of the public.

CORRECTIVE ACTION The immediate corrective action was to shift the transfer switch to the Standby position and administrative 1y to hold in that position with a SECURE CARD. This transferred the control power back to 12 Battery, whose power l cable (No. 1DCB 83) is fire protected. The Normal and Standby positions u ll

, be reversed and the drawings, procedures, and other documents will be revised

! to show the correct configuration.

The administrative control procedural problems which allowed the condition to be created have already been correc.ted.

The internal technical review of the 10 CFR 50 Appendix R design versus the as built conditions will be completed to assure that all discrepancies are identified, and corrections made as necessary.

PREVIOUS SIMILAR EVENTS There have been no previous similar events at Prairie Island.

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