ML20155D658

Forwards Description of 10CFR50,App R Deficiencies Re Decoupling Circuitry for Train B Emergency Diesel Generator & fire-induced Spurious Operations & Clarification of Two Items in NRC 871112 Safety Evaluation Granting Exemption

ML20155D658
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	06/08/1988
From:	Cockfield D PORTLAND GENERAL ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
NUDOCS 8806150350
Download: ML20155D658 (10)

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David W. Cockfield Vice President, Nuclear Juno 8, 1988 Trojan Nuclear Plant Docket 50-344 License NPF-1 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington DC 20555

Dear Sirs:

Resolution of Appendix R Deficiencies and Clarifications to Exemption This lottor is written to notify the Nuclear Regulatory Commission (NRC) of two fire protection deficiencies related to Appendix R to Title 10, Code of Federal Regulations Section 50 (10 CFR 50), and our proposed plans and schedules for correcting these deficiencies. This letter also providos clarifications to two items described in the November 12, 1987 Appendix R exemption granted by the NRC.

The two Appendix R deficiencies are (a) the decoupling circuitry for the Train B emergency diosol gonocator (EDG), and (b) a firo-induced spurious operation (s) which could damago redundant trains of centrifugal charging pumps (CCPs). Prob-lem descriptions and corrective action plans and schedules for both those defi-ciencies are detailed in Attachments 1 and 2, respectively.

Attachment 3 provides a detailed clarification to two items described in the Safety Evaluation enclosed with the November 12, 1987 Appendix R exemption granted by the NRC.

We would bo pleased to discuss any questions or comments you may have regarding this information.

Sincerely, Attachment c: Mr. John B. Martin

~ l V Regional Administrator, Region V U.S. Nuclear Regulatory Commission Mr. Bill Di:.on Stato of Oregon Department of Energy Mr. R. C. Barr NRC Resident Inspector Trojan Nuclear Plant

<o 8806150350 880608 PDR ADOCK 05000344 F ncn 1215 W Saimon Sueet. Portuni Oregy1972C4

Trojan Nuclear Plant Document Control Desk Docket 50-344 June 8, 1988 Licenso NPF-1 Attachment 1 DESCRIPTION OF DECOUPLE CnCUIT DEFICIENCIES FOR TRAIN B EMERGENCY DIESEL GENERATOR AND CORRECTIVE ACTION PLAN AND SCllEDULRS Description A review of the Train B Emergency Diosol Generator (EDG) decoupling circu-itry revealed two design deficiencies which could provent operation of the EDG following a fire in the control room or cable spreading room (CR/CSR).

The first deficiency involves a postulated single hot short to Cablo BA2S which could permanently damage the electrical governor of the EDG and prevent its subsequent operation. Cable BA2S is used to provido electrical signals to motors in the control room.

The second deficiency involves a postulated single hot short to Cablo BA2082E which could force the EDG to maintain itself at an idle speed and prevent its subsequent operation.

Corrective Actions The first deficiency will be resolved by providing a separato electrical circuit to supply only the control room meters. A second set of current transformers will bo installed in the local EDG control panol to power this separato electrical circuit. This modification will ensure adequato protection for the EDG electrical governor.

The second deficiency will be resolved by modifying the existing decouple switch circuitry in the local EDG control panel. The proposed modification will allow Plant operators to overcome this particular hot short condition by operation of the decouple switch. Use of the decouple switch is currently required by Emergency Fire Procedures for fires in the CR/CSR which would create this hot-short condition.

Corrective Action Schedules All actions required to correct the two deficiencies described abovo will be completed prior to restart from the current refueling outage.

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Trojtn Nuclscr Pitnt Document Control Desk Docket 50-344 June 8, 1988 Licenso-NPF-1 Attachment 2 Page 1 of 4 f

DESCRIPTION OF SPURIOUS OPERATION PROBLEM FOR THE CENTRIFUGAL CHARGINC PUMPS (CCPs) AND CORRECTIVE ACTION PLAN AND SCHEDULES Descript.'on Section III.C.1'of Appendix R to 10 CFR 50 requiros, in part, that one train of systems necessary to achieve and maintain hot shutdown condi-tions be froo of fire damage.Section III.G.2 of Appendix R prescribes specific criteria for ensuring that cables and equipment (including associated circuits) of redundant trains of safe shutdown systems located in the same fire area are free of fire damage.

To demonstrate the safe shutdown capability of the Trojan Nuclear Plant, a worst-caso exposure fire is assumed to occur in a given Plant fire area. In addition to the fire, a concurrent loss of offsite power is assumed.

The CCPs are ro"iod upon to provide Reactor Coolant System (RCS) makeup and Reactor Coolant Pump (RCP) seal cooling. One CCP is required for safo shutdown followl.ig an Appendix R postulated exposure fire.

There are two scenarios involving the outlet valves for the volume con-trol tank (VCT), MO-112B and C, that could result in the loss of both CCPs, P205A and B:

1. As described in FSAR Table 8.3-2, Dioscl Loading Sequence, a loss of offsito power would result in the shutdown sequencer starting both CCPs. With both CCPs operating, a fire-induced spurious closure of MO-112B or C would stop the suction flow from the VCT. This would quickly damage both pumps.

2. There are several fire areas in which the control cables for the VCT outlet valves are located with the power and/or control cables for one of the CCPs. As a result, one fire could cause the spurious operation of MO-112B or C and result in damaging the CCP in opera-tion. The same fire could also damage the power or control cables for the other CCP. The not result is that a single fire could dis-able both CCPs, whether or not offsito power is lost.

Fire-induced spurious closure of the CCP miniflow isolation valves, MO-8110 and MO-8111, could also lead to damage of both CCPs. This is of concern only in the event of a concurrent loss of offsito power (loss of load). A low discharge flow (loss than 60 gpm) from each of the CCPs into the RCS (requiring the nood for miniflow) could result from either (a) high RCS pressure following the loss of load transient, or (b) from the throttling down of FCV-121 to restoro pressurizor level to its no-load value.

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Trojan Nuclear Plant Document Control Desk Docket 50-344 June 8, 1988 License NPF-1 Attachment 2 Page 2 of 4 Corrective Actions l

Several actions are required to resolvo tho spurious operation problem l for the CCPs. Table 1 summarizes in matrix format, for each relevant  !

fire area, how this problem will be corrected and any interim I compensatory measures applied. I l

First, the positivo displacement charging pump (PDP), P-217, will be used l i

as an alternato charging sourco for those fires that result in loss of '

both CCPs. The following changes are required to enablo using the PDP:

1. Although the PDP is currently poworod from an emergency diesel gono-rator (EDG)-backed Train B sourco, it will be necessary to provido power to the PDP from an EDG-backed Train A source. This will be accomplished by routing a new 4.16-kV power cable from the Train A switchgoar room in the Turbino Building to a transfor switch on the 25-foot lovel of the Auxiliary Building. The transfer switch will be in the same fire area as the PDP (Fire Area A1) and will allow an operator to align the PDP to either the Train A EDG or the. Train B EDC. A mechanical interlock will prevent the PDP from being aligned to both power supplies at the same time. Power to the transfer switch will be supplied from the Train A switchgear room in one of three ways: installation of a new Class 1E breaker in a sparo cubicle in Bus A01; installation of a new non-Class IE breaker and cubicle poworod from Bus A05; or connection to an existing Class 18 breaker in Bus A01 which currently services the switchyard. An engineering ovaluation will determine the preforced option of the procoding three choices.

2. Use of the PDP will also require provision of a backup source of nitrogen to provido motivo power for the spoed controller. This change to the pneumatic control system will enable local control of the PDP spood on the 25-foot level of the Auxiliary Building in the event of a loss of offsite power or the unavailability of the com-pressed air system. Backup nitrogen is required because the com-prossed air system is not relied upon for safe shutdown following a fire.

3. In order to provent spurious operation of the PDP, the circuit breakers (in each switchgoar room) will be opened and the control power fusos removed. Power for PDP operation will be provided via operator action by closing breakors in the appropriato switchgoar room. Installation of the control power fuses will not be necessary for local control.

Second, for a fire in the same fire area where the PDP is located (Firo Area A1), the cables for the motor-operated valves (MOVs) from the VCT w,11 bo protected with throo-hour rated fire wraps, or they will be relocated outside the firo area, to prevent a spurious operation from

Trajan Nuciser Pignt Document Control Desk Docket 50-344 June 8, 1980 Licenso NPF-1 Attachment 2 Page 3 of 4 damaging a CCP. Cables for one of the MOVs from the refueling water storage tank (RWST), MO-112D and E, will also be protected by providing theco-hour rated fire wraps, or by relocating the cables outside of the fire area. This will ensure that a source of borated water will be available for RCS makeup and RCP seal cooling, without need for operator access through the 25-foot level of the Auxiliary Building.

Third, a separato firo area will bo defined for the VCT outlet valves (MO-112B and C). These valves are located in Fire Area Al on the 45-foot level of the Auxiliary Building. This action will require a detailed fira area boundary evaluation and may or may not involvo'the addition or modification of fire barriors.

Fourth, a review will bo performed to dotormine if adequato emergency battery lighting is available in the Auxiliary Building to support those operator actions necessary to locally operato the PDP. If necessary, additional emergency battery lighting will be installed.

Finally, the Emergency Fire Procedures will be revised to provide instructions for operating the PDP.

Corrective Action Schedules Correctivo action schedules for the deficiencies described above are proposed as follows:

1. Prior to Restart from the Current Refueling Outage:

Completo all changes necessary to assure that a fire in the control room or cable spreading room (CR/CSR) will not result in loss of all charging capability. These changes include opening the power supply breaker and removing control power fuses for the positive displaco-ment charging pump (PDP); installing a backup nitrogen supply to enablo local operation of the PDP' speed controller independent of the compressed air system; and revising Emergency Fire Proceduro (EFP) -1, "Alternativo Shutdown for Evacuation of Control Room Caused by Firo",

to provido instructions for operating the PDP. In addition, EFP-0 "Procedure in the Evant of a Fire", will bo revised to provido instructions for opersting the PDP for fires in certain other fire areas in the Auxiliary and Turbine Buildings.

In addition to the above, hourly fire patrols will be provided in the Traits B switchgear room (Firo Area C2) and various elevations of the Auxiliary Building (as identified in Table 1) as an interim compen-satory measure for fires in areas other than the CR/CSR.

Trojen Nucis!r Pltnt Document' Control Desk Docket 50-344 June 8, 1988

' License NPF-1 Attachment 2 Page 4 of 4

2. Prior to October 1. 1988:

Install three-hour rated cable wraps for motor-operated valve cir-cults on, or relocate these circuits independent of, the 25-foot level of the Auxiliary Building, as described above.

3. Prior to Restart from the 1989 Refueling Outage (June 1. 1989):

Provide a Train A electrical power supply and transfer switch for the PDP as described above; define a new fire area for the volume control tank outlet valves (MO-112B and C), and, if required, make fire bar-rier modifications; provide additional emergency battery lighting units, if required, to support operation of the PDP; and complete revisions to the Emergency Fire Procedures to enable PDP operation for all affected fire areas.

DRS/mr 2691P588

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PROBLEM / RESOLUTION MATRIX FOR SPURIOUS OPERATION IMPACT ON CENTRIFUGAL CHARGING PUMPS Page 1 of 2

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Fire Area P-205 P-217 MD-112 MO- Compensatory No. Description A B (Train B) B C D E 8110 8111 Problem Resolution Measure Al Auxiliary Building, X X X X X X X X(4) X(4) Loss of CCP suction. Use P-205A(.1) Wrap 1-hour fire patrol on Elevation 5 ft through or relocate circuits Elevations 5 foot, 77 ft for MO-ll2BSC, and 25 foot, and 45 foot D or E. Provide of Auxiliary Building separate fire area (Area A1).

for MO-il2B&C.

A2 Auxiliary Building, X X X Loss of CCP suction. Use P-217 (breaker None required.

Elevation 5 ft to be opened and fuses removed before restart).

A3 Auxiliary Building, X X X X X X X Loss of CCP suction. Use P-217 (breaker None required.

P-205A Roarp to be opened and fuses removed before restart).

A4 Auxiliary / Fuel Build- X

' X X X X X X Loss of CCP suction. Use P-217 (breaker Mone required.

ings, Elevation 45 ft to be opened and through 77 ft fuses removed before restart).

A4a Auxiliary / Fuel Build- X X X X X Loss of CCP suction. Provide Train A 1-hour fire patrol on ings, Elevations 61 ft power supply for Elevation 61 ft of and 77 ft P-217 independent Area A4a.

of Area A4a.

C2 Control Building, X X X X X Loss of CCP suction and Provide Train A 1-hour fire patrol in Train B Switchgear miniflow. power supply for Area C2.

Room P-217 independent of Area C2.

(1) Cable for P-205A currently provided with 3-hour fire wrap in Area Al.

(2) Control cables only; not required for solid breaker operation. Breaker for P-217 will be opened and control power fuses removed to prevent spurious pump operation.

(3) Enbedded conduit in less than 6 inches of concrete.

(4) Fault in cables cannot cause spurious valve closure.

PROBLEM / RESOLUTION MATRIX FOR SPURIOUS OPERATION IMPACT ON CENTRIFUGAL CHARGING PUMPS Page 2 of 2 Fire Area P-205 P-217 MD-ll2 MD- Compensatory No. Description A B (Train B) B C D E 8110 8111 Problem' Resolution Measure C7 Control Building, X X X( X X X X X X Loss of CCP suction and Use P-217 (breaker None required.

Cable Spreading Room miniflow. to be opened and fuses removed before restart).

Cll Control Building, X X X X X X X X X Loss of CCP suction and Use P-217 (breaker None required.

Col. trol Room miniflow. to be opened and fuses removed before restart).

Tl Turbine Building, X X X X Loss of CCP suction and Use P-217 (breaker None required.

Elevation 45 ft miniflow. to be opened and through 93 ft fuses removed before restart).

T8 Turbine Building, X X X X Loss of CCP suction and Use P-217 (breaker None required.

Train A Switchgear miniflow. to be opened and Room fuses removed before restart).

(1) Cable for P-205A currently provided with 3-hour fire wrap in Area Al. ,

(2) Control cables only; not required for solid breaker operation. Breaker for P-217 will be opened and control power fuses removed to prevent spurious pump operation.

(3) Embedded conduit in less than 6 inches of concrete.

(4) Fault in cables cannot cause spurious valve closure.

DRS/2693P

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' Trojan Nuclea'r. Plant . Document Control Desk--

Docket'50-344 June 8, 1988 Licenso NPF-1 Attachment 3 Page 1 of 2 i

CLARIFICATIONS TO NOVEMBER 12, 1987 NUCLEAR REGULATORY COMMISSION (NRC) EXEMPTION ON APPENDIX n ,

This attachment identifies two items in the Safety Evaluation for the November 12, 1987 exemption granted by the NRC.for Section III.G.2 of

' Appendix R to Title X to the Code,of Federal Regulations, Section 50 (10 CFR-50) which do not accurately describe the configuration of fire protection' features at frojan.

Fire Area E1/Tl Boundary Wall The first item concerns the fire protection features provided at the Fire Area E1/T1 boundary wall. .The last paragraph of Section 5.2.2.3 of the safety Evaluation states that "The metal section of the wall will be protected with an_ automatic water suppression system to provide cooling and structural protection of the wall", . and that ". . . the system will discharge water directly onto the structural steel and metal siding to provide cooling and structural protection of the wall".

- It was Portland General Electric Company's (PGE's) original intention to provide a water spray system whose function was to cool and protect the metal siding and supporting steol; however, this was changed to provide a wet pipo sprinkler system for the areas adjacent to the wall to prevent propagation of a fire. The fire protection objective of the wet pipe sprinkler system is the same, ie, prevent a Turbine Building fire in Area T1 from propagating to the electrical penotration area in Area El, which contains safo shutdown electrical cabling. The primary advantages of using an automatic wet pipo sprinkler system, rather than an automatic water spray system, include the following

• The sprinkler system will control and/or extinguish a fire in the Turbino Building. A water spray system on the wall would not control and/or extinguish a fire.

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• The estimated flow of the sprinkler system will be 1,000 gpm. The estimated flow to the water spray system would requiro 2,800 gpm, not including additional water required to extinguish the fire.

, . The sprinkler system's reliability is high, with inadvertent dis-chargo of water very unlikely. The water spray system's reliability is not as high, with an inadvertent discharge of system involving water flow from all nozzlos.

This chango was discussed with the NRC during a November 26, 1985 meeting at Trojan; was documented in a lotter to the NRC dated December 20, 1985; and was described in Amendment 3 to PCE-1012. "Trojan Nuclear Plant Fire Protection Plan", which was submitted to the NRC on Juno 30, 1987.

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• Trojan Nucicir.Plcnt Document Control D2ck s . Docket 50-344 June 8, 1988 License NPF-1 Attachment 3 Pago 2 of 2 Firo Area Tl 69-Foot Floor Slab The second item concerns the fire protection features.provided in Fire

. Area T1 at the 69-foot floor slab above the Emergency Diesel Generator (EDG) air intakes. The last paragraph of Section 6.2 of the Safety Eval-ustion states that "The Licensoo has committed to . . . upgrade the floor slab to a three-hour rated fire barrior".

The concrete portion of the floor does qualify for a three-hour rating and all penetrations have been upgraded by installation of three-hour rated seals; howevor, the structural steel supporting the slab has not been upgraded. Since supporting structural steel is an integral part of a fire barrier, the 69-foot floor slab is not actually a rated fire bar-rier. The elevation 69-foot floor slab is erroneously described as a throo-hour rated fire barrior on Pages 3.4-62 and 3.4-65 of Volume I to PGE-1012, and Pages 5-27 and 5-28 of Volume II to PCE-1012 (those errors will be corrected in the next update to PGE-1012). Page 2-50 of Volume II to PGE-1012 correctly describes the upgrading as installation of three-hour fire-rated seals in all slab openings. In all these references, however, the document is silant on the unprotected structural steel sup-porting the floor slab.

The structural steel supporting the slab consists of unfireproofed beams and columns. A method for determining an approximate fire tolerance of this unprotected steel is described in Section 4.2.2 of Appenoix C to Volume II of PGE-1012. Application of this method to the supporting beams indicates a fire tolerance of 15 to 30 minutes of exposure to temperatures from the standard fire specified in American Society for Testing and Materials (ASTM) Designation E119. A fire tolerance of 35 to 40 minutes is indicated for supporting columns. Based on the in situ and estimated transient combustibles in the area under the slab, the approximato equiva-lent fire soverity is estimated to be as much as 70 minutes.

It was nover PGE's intention to upgrado the protection of structural steel supporting the 69-foot floor slab. Tho justifications for this were the normally low combustible loading on the 45-foot elevation, the open areas with high ceilings, and the addition of an automatic wet pipe sprinkler system under the slab. The wot-pipe sprinkler system is not designed to spray directly on the structural steel but will provido a water density of 0.3 GPM/sq ft of floor area for the most remote 2500 sq ft. The system will extinguish fires whilo also maintaining the temperaturo underneath the slab, near the beams, below the 1000 degroo critical strength temper-aturo. Temperatures near a column could exceed the 1000 degroo critical temperature for a short time duo to a firo starting next to the column; however, the operation of the sprinkler system would assure that the effect on the column would be loss than the fire tolerance of the column as described above. Provision of a wot-pipe sprinkler system in the area is considered an acceptablo alternato to fireproofing the support beams and columns. Theso justifications should have been included in PGE-1012.

The 69-foot floor slab should be described as a concreto floor slab with sealed penetration openings which is supported by unfiroproofod structural steel. Theso justifications and descriptions will be included in the next update to PGE-1012.

DRS/mr/2691P.588 l