ML20012D165

LER 90-004-00:on 900208,determined That Holes Left in Auxiliary Shutdown Panel Could Allow Water Spray Into Cabinet.Cause Unknown.Holes Covered W/Duct Tape & Repaired. W/900319 Ltr

ML20012D165
Person / Time
Site:	McGuire
Issue date:	03/19/1990
From:	Mcconnell T, Sipe A DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-004-01, LER-90-4-1, NUDOCS 9003260559
Download: ML20012D165 (8)

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DUKEPOWER March 19, 1990 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555

Subject:

McGuire Nuclear Station Unit 1 Docket No. 50-369 Licensee Event Report 369/90-04 Gentlemen:

Pursuant to 10 CFR 50.73 Sections (a)(1) and (d), attached is Licensee Event Report 369/90-04 concerning holes that were lef t in the Auxiliary Shutdown Panel in violation of the Environmental Seal program. This report is being submitted in accordance with 10 CFR 50.73(a)(2)(1)(B). This event is considered to be of no significance with respect to the health and safety of the public.

Very truly yours, C

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T.L. McConnell DVE/ADJ/cb1 Attachment xc: Mr. S.D. Ebneter American Nuclear Insurers Administrator, Region II c/o Dottie Sherman, ANI Library U.S. Nuclear Regulatory Commission The Exchange, Suit 245 101 Marietta St., NW, Suite 2900 270 Farmington Avenue Atlanta, GA 30323 Farmington, CT 06032 INPO Records Center Mr. Darl Hood Suite 1500 U.S. Nuclear Regulatory Commission 1100 Circle 75 Parkway Office of Nuclear Reactor Regulation Atlanta, GA 30339 Washington, D.C. 20555 _

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M&M Nuclear Consultants Mr. P.K. Van Doorn 1221 Avenue of the Americas NRC Resident Inspector bJ; f New York, NY 10020 McGuire Nuclear Station 9003260509 900319 PDR ADOCK 05000369

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. . LER 369/90-04 Pete 2 bxc: B.W. Bline L.G. Bost J.S. Warren R.L. Gill R.M. Glover (CNS)

T.D. Curtis (ONS)

P.R. lierran S.S. Kilborn (W)

R.E. Lopez-Ibanez M.A. Mullen R.O. Sharpe (MNS)

G.B. Swindlehurst K.D. Thomas M.S. Tuckman L.E. Weaver R.L. Weber J.D. Wylie (PSD)

J.W. Willis QA Tech. Services NRC Coordinator (EC 12/55)

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[ vas trere. remP== f x*tetto suemssio= 04 fts ] No O! 6 3 10 Q 10 Au,m Acf ev , w am am .e ewe-mm, um. ve.e-e emme. s~e,> osi On February 8, 1990, Quality Assurance (QA) personnel performed a random walk through inspection of electrical equipment in the Auxiliary Building. The inspection was performed to determine if the station was in compliance with the Environmental Seal Program. QA personnel inspected the Unit 1 Auxiliary Shutdown Panel (ASP) and found several holes in the panel. QA personnel wrote Problem Investigation Report (PIR) 0-M90-0038 to document the discovery of the holes in the ASP. Subsequently, Compliance personnel requested that Design Engineering personnel perform an Operability Evaluation to determine the status of the ASP. On February 15, 1990, Design Engineering personnel issued an Operability Evaluation I

and determined that because the holes in the ASP would allow water spray into the I cabinet the operability of the components controlled from the ASP is indeterminate; therefore, they are considered inoperable. This event is assigned a cause of Unknown. It could not be determined during this investigation when or under what direction the holes were left in the panel. The McGuire Safety Review Group will continue to investigate this event and will write an addendum if the cause is discovered. Construction and Maintenance Division (CMD) personnel have begun to plug the holes in the ASP. Unit I was in Mode 6 (Refueling) at the time this event was discovered.

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Background

The ASP [EIIS:JL] is provided to ensure sufficient instrumentation and controls are available to bring the plaat to Hot Shutdown in the unlikely event the Control Room

[EIIS:NA] must be evacuated.

Technical Specification 3.3.3.5 states that the remote shutdown monitoring instrumentation shall be operable in Modes 1 (Power Operation), Mode 2 (Startup),

and Mode 3 (Hot Standby).

The environmental sealing requirements for safety related electrical boxes and equipment are conveyed to the station through Installation Specification MCS-1390.01-00.53, Safety Related Electrical Equipment Sealing for the Turbine

[EIIS:NM], Service [EIIS:MF] and Auxiliary Building [EIIS:NF], Annulus and Outdoor Yard Areas. This specification was used by Station personnel to generate procedure IP/0/A/3090/10, Procedure for Sealing Safety Related Equipment Outside of Containment and Doghousas. These sealing requirements protect electrical terminations from water spray and other hostile environmental effects.

The ASP is classified as a National Electrical Manufacturers Association (NEMA) 4 enclosure. A NEMA 4 enclosure is a watertight, dust tight enclosure intended for use indoors to protect enclosed equipment f rom water splashing, seepage, or hose directed spray. The enclosures will have neoprene gasketed fitted doors [EIIS:DR]

with several latch mechanisms spaced around the door to provide an even and tight door seal [EIIS: SEAL].

One-half hour rated fire blankets were installed on the ASP before~ initial startup of Unit I to comply with the requirements of 10CFR50 Appendix R. Appendix R stated in part that one train of equipment necessary to achieve Hot Shutdown from either ~

the Control Room or emergency control stations must be maintained f_ree of fire damage by a single fire. For the station to comply with this requirement, the ASP and its associated cables [EIIS:CBL] were wrapped with one-half hour rated fire blankets. After the Standby Shutdown Facility (SSF) was made operable in 1983, the extra fire protection provided by the fire blankets was no longer needed. With the SSF operable, a single fire would not be able to prevent bringing the unit to Hot Standby. A letter dated August 31, 1983, from Safety Review, Analysis and Licensing Division stated, "the one half hour rated fire barriers installed on various cooponents as interim measures prior to SSF operability are no longer necessary since the SSF is now operable. Replacement of the Unit 1 barriers, if removed, is not required."

Description of Event On February 8, 1990, QA personnel performed a random walk through inspection of electrical equipment in the Auxiliary Building. The inspection was performed to determine if the station was in compliance with the Environmental Seal Program for '

electrical cabinets. QA personnel inspected the Unit 1 ASP and discovered several

. holes in the panel. Since the ASP is designated as a NEMA 4 enclosure, QA comu ma av.s. c ni tese- m e, e l

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McGuire Nuclear Station, Unit 1 0 l5 lo lo j o l3 ] 6l 9 9l0 0l0]4 0l0 oj 3 or 0 l6 rixt rn --. . w. w =ac s asu w mi personnel initiated PIR 0-M90-0038 to document the discovery of the holes. Later, it was determined by station personnel that there were approximately 90 one quarter inch holes in the ASP. Design Engineering personnel performed an Operability Evaluation for the ASP and on February 15, 1990, determined that the possibility of water spray intrusion into the ASP caused the operability of the components controlled by the ASP to be indeterminate; therefore, they are considered inoperable. Unit I was in Mode 6 at that time. The ASP is required to be operable in Modes 1, 2, and 3.

Conclusion This event is assigned a cause of Unknown. It could not be determined during the time frame of this investigation when or under what direction the fire blankets were removed from the ASP without filling the holes drilled in the panel to hold the iire blankets in place.

This investigation included discussions with personnel in the following groups:

Operations, Planning, Mechanical Maintenance, Instrumentation and Electrical, Mechanical Engineering Services, Compliance, Project Services, Construction and Maintenance Division, Integrated Scheduling, and General Office Design Engineering.

Also, a review of work requests was performed for the years 1983, 1984, 1985, and 1986. Discussions with the personnel mentioned led to the belief that the fire blankets were most likely removed during this time. Also reviewed were Nuclear Station Modifications that involved fire protection, the ASP or the Auxiliary Feedwater System [EIIS:BA]. It could not be determined during this investigation when the fire blankets were removed or by what process and why the holes in the ASP were not repaired.

The McGuire Safety Review Group (MSRG) will continue to investigate this event and will write an addendum to this LER if the details of the fire blanket removal can be determined.

The holes in the ASP are being repaired in accordance with McGuire Exempt Variation Notice (MEVN) 2241 and WR 953722. This work will be completed prior to Unit I reaching Mode 3.

A review of McGuire LERs for the past 24 months revealed several events with a cause of Unknown. None of these reports involved a TS violation because of a violation of the Environmental Seal Program or involved the Auxiliary Shutdown Panel. This event is not considered recurring. ,

This event is not Nuclear Plant Reliability Data System (NPRDS) reportable.

There were no personnel injuries, radiation overexposures or uncontrolled releases of radioactive materials as a result of this event.

CORRECTIVE ACTIONS:

Immediate: The holes in the ASP were covered with duct tape, i geoavsma .v.s. cro, teio ,so se cooio

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0]O 0l4 OF 0 l6 nxm . ,wwe %asimnn Subsequent: CMD personnel according to MEVN 2241, began to repair the holes in the ASP.

Planned: The MSRG will investigate this event further to determine when the fire blankets were removed from ASP.

SAFETY ANALYSIS:

The numerous drilled penetrations found in the Unit 1 ASP resulted in indeterminate operability of remote shutdown instrumentation as determined in the Design Engineering Operability Evaluation. Inoperability is due to the possibility of water intrusion into the particular portions of the panel housing the electrical termination strips. The water source is from a postulated break or leak of any of several high and low flow pipe lines located in the immediate area. Since the ASP control circuits parallel those of the Control Room downstream of the circuit fuses, the presence of water on the electrical connections presents an electrical short hazard; therefore, the consequences relative to plant operations are indeterminate.

This safety analysis will address the potential nuclear safety consequences of such an electrical short; the precursor event and the postuleted affects will be outlined under two operational circumstances.

l The failure mechanism, which will be common under both circumstances, involves water entry into the A or B Train terminal strip compartment, located at either end of the ASP, causing some degree of circuit shorting. Circumstance A shall be the occurrence of the electrical short at a time when the ASP is required for remote shutdown following a Control Room evacuation. It is postulated that electrical shorting would be to an extent such that manipulation of certain components would be prevented and the ability to attain a Hot Standby condition would be compromised. Circumstance B involves the water induced electrical short occurring during normal operation of the Control Room. Under this circumstance, the short is postulated to cause either a spurious component actuation, a transfer of individual component control away from the Control Room, or a loss of all remote control for an individual component.

In the unlikely event of a necessary Control Room evacuation, the ASP is the means for achieving a unit shutdown condition, except in the postulated cases of a plant fire or sabotage event, in which cases the SSF is utilized. Activities associated with the Control Room evacuation are directed by abnormal procedure AP/1/A/5500/17, Loss of Control Room. The first operational circumstance involves the premise that the effects of the water induced electrical short withip the ASP are present when a control transfer to the panel is necessary. Since the degree of malfunctioning could be minimal and limited to only certain components, operating personnel may elect to remain at the ASP and alter activities accordingly. However, the Loss of Control Room Procedure directs that if the ASP controls do not respond properly, that the SSF is to be utilized according to operating procedure OP/1/B/6100/17, Operation of the Standby Shutdown Facility. Use of the SSF is an alternate and independent means to achieve a Hot Standby condition. An electri~ cal short associated with the ASP would not affect control from the SSF. Routine maintenance and surveillance testing would have made the SSF unavailable at times, but is normally maintained in an operable condition. The ability to trip the reactor

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0l0 015 0F 0 l6 taxts . w. ancs an m nn would not be compromised by an electrical short as the trip function is not provided on the ASP. Rather, a Reactor Trip is accomplished locally from the Reactor Trip Switchgear on command according to the Loss of Control Room procedure.

The scenario described for Circumstance A, consisting of a Loss of Control Room event coincident with a break or directed leak of local low energy piping, is considered to be of insignificant possibility.

Although the sequence of events surrounding Circumstance B is more likely since the requirement for a control evacuation is not included, the possibility of occurrence remains insignificant. As previously stated, the electrical short is considered capable of causing a transfer of control away from the Control Room, spurious equipment actuation, or a loss of all remote control (relative to the equipment).

The electrical design of the control system provides for a Control Room annunciating alarm when an ASP selector switch has been placed in the local operating position. If an unintentional control transfer should occur, Control Room personnel would be made aware of the condition by the annunciating circuit and appropriate corrective measures could be taken. Transfer of control for a particular component does not infer that an accompanying plant transient results nor eliminates the capability of switchgear control.

l l Spurious equipment actuation is a consequence also of which Control Room personnel would most likely be aware (depending on the component actuated and plant conditions). The resulting plant transient, if any, would not place the unit in a condition not already analyzed in the Final Safety Analysis Report Accident t Analysis. Perhaps the most vulnerable components controlled from the ASP and capable of a significant impact on plant conditions are the pressurizer Power-Operated Relief Valves (PORVs). The ASP does not provide remote control for the pressurizer PORV block valves; therefore, the block valves would not be similarly affected by an electrical short and would remain available for isolation of the PORV. More conservatively, the spurious PORV opening event as presented in the accident analysis, does not take credit for availability of the block valves.

This primary depressurization event is bounded by the more limiting inadvertent opening of a pressurizer safety valve.

The ASP is located in the Auxiliary Feedwater (CA) Pump Room where the potential water flood and leak sources within close proximity include:

a) 36-inch Nuclear Service Water (RN) pipe (RN pump suction train crossover) b) Auxiliary Feedwater Pumps and associated piping, particularly an 8 inch CA Pump 1A suction line c) 3/4 inch and 4 inch Liquid Waste System (WL) piping associated with Ventilation Unit Condensate Drain Tank (VUCDT) Radiation Monitor (EMF-44) d) Ventilation Unit Condensate Drain Tank (4000 gal.).

There have been no known instances where the ASP, with unsealed penetrations, has been subjected to harsh environmental conditions involving water. The water sources, as they have the potential to affect the ASP, pose either a flooding or NIC 90mW 344A 'U.S. Chh 196 6 - 5 & 5 F 9 W4t M' t9 43)

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0l0 Ol6 OF 0 l6 rixtin . w. .an wancs an4 m i leaking spray source. Although the likelihood of a flood from a break is far less than spray from a leak, it is inevitable that the flood water would eventually enter thrcugh the holes of the ASP compartment. The spray from a pipe leak, on the other hand, needs to be directed onto the panel in the vicinity of the hole.

The most vulnerable flooding source is considered to be the 36 inch RN line, and specifically the RN strainer expansion joints. In conjunction with Auxiliary Shutdown Panel Flooding Study MGDS-0100/00, it was identified that a drawing specified cylindrical cover for protection of the expansion joint had not been installed. The protective cover has since been installed, thereby reducing the likelihood of expansion joint failure by external means and also would reduce the resulting flow rate into the CA pump Room should a joint randomly fail.

The two potential spray sources of higher concern are the VL System EMF 44 sample lines and the CA Pump 1A Suction line. Both are located within approximately three feet of the electrical termination compartment described earlier. The VL system piping in question is only pressurized during periods of VUCDT discharge, expected to occur daily but depends on plant conditions. The discharge pressure of the VUCDT pumps is relatively low (design pressure of 120 psig in stainless steel) and i is therefore not expected to be a pipe failure hazard. The fluid in the CA pump r

suction piping (carbon steel) is normally static at a pressure ranging form 25 to l 35 psig, depending on the suction source. This value is well below the design pressure of 135 psig. Because the system is not subject to the dynamic stresses of continuous flow, and the low operating pressure at the suction, the CA system piping in question is likewise not considered to be a pipe failure hazard.

Although the Unit 1 ASP existed in a degraded condition for an extended length of time, it is concluded that a local pipe failure leading to an electrical short within a ASP is an unlikely occurrence, that the operational consequences of the electrical short would not be undetectable, and that an alternate and independent means of remote unit shutdown was maintained as practical.

This event did not affect the health and safety of the public, i

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