ST-HL-AE-1950, Forwards Responses to Electrical Concerns Identified During 870128-30 Audits of Electrical Sys,Instrumentation & Control Sys,Spds & Crdr

Forwards Responses to Electrical Concerns Identified During 870128-30 Audits of Electrical Sys,Instrumentation & Control Sys,Spds & Crdr

ML20207R946
Person / Time
Site:	South Texas
Issue date:	03/11/1987
From:	Wisenburg M HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ST-HL-AE-1950, NUDOCS 8703180335
Download: ML20207R946 (11)

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March 11, 1987 ST-HL-AE-1950 File No.: G4.02 10CFR50 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Responses to Electrical Systems Audit Items

Reference:

A. Notes From Review Meeting with Instrumentation & Control Systems Branch; M. R. Wisenburg, H14P Letter to George W.

Knighton, NRC; dated May 13, 1985; ST-HL-AE-1239 During the period of January 28-30, 1987, the NRC staff held audits in the areas of Electrical Systems, Instrumentation & Control (I6C) Systems, Control Room Design Review (CRDR), and the Safety Parameter Display System (SPDS) at the South Texas Project site. An exit meeting was held at the conclusion of each audit to summarize the concerns which had been identified.

Responses to the concerns identified during the Electrical audit are provided in the attachment.

If you should have any questions on this matter, please contact Mr.

J. S. Phelps at (713) 993-1367.

JW w M. R. Wis nburg Deputy Prdject Manager JSP/yd

Attachment:

1. Responses to Electrical Systems Audit Items

2. ESF Status Monitoring Lampbox Arrangement for ESF Bus A S

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8703180335 070311 PDR ADOCK 03000498 A PDR

ST-HL-AE-1950 Filo No.: G4.02 flouston Lighting & Power Company pag 2 cc:

Regional Administrator, Region IV M.B. Lee /J.E. Malaski Nuclear Regulatory Commission City of Austin 611 Ryan Plaza Drive, Suite 1000 P.O. Box 1088 Arlington, TX 76011 Austin, TX 78767-8814 N. Prasad Kadambi, Project Manager M.T. Hardt/A. von Rosenberg U.S. Nuclear Regulatory Commission City Public Service Board 7920 Norfolk Avenue P.O. Box 1771 Bethesda, MD 20814 San Antonio, TX 78296 Robert L. Perch, Project Manager Advisory Committee on Reactor Safeguards U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission 7920 Norfolk Avenue 1717 H Street Bethesda, MD 20814 Washington, DC 20555 Dan R. Carpenter Senior Resident Inspector / Operations c/o U.S. Nuclear Regulatory Commission P.O. Box 910 Bay City, TX 77414 Claude E. Johnson Senior Resident Inspector /STP c/o U.S. Nuclear Regulatory Commission P.O. Box 910 Bay City, TX 77414 M.D. Schwarz, Jr. , Esquire Baker & Botts

- One Shell Plaza Houston, TX 77002 J.R. Newman, Esquire Newman & Holtzinger, P.C.

1615 L Street, N.W.

Washington, DC 20036 T.V. Shockley/R.L. Range Central Power & Light Company P. O. Box 2121

- Corpus Christi, TX 78403 Ll\nrc\qy. Revised 2/3/87 f

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• ' Attcchment 1 ST-HL-AE-1950 Page 1 of 8 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Responses to Electrical Audit Items

1. Concern: The reviewer inspected Raychem cable-to-cable terminations (splices) at penetration B1PHEP036I and two were found to be improperly installed. This raised a concern for the proper installation of all Raychem splices.

• Response: All safety-related. cable-to-cable terminations (splices) at the in'-board side of the containment penetrations are documented on a computerized cable report. The termination documentation associated with the cable-to-cable splices on this report was reviewed to verify that materials used in the Raychem splice conformed to the vendor's installation instructions. This review has been completed for safety-related penetration splices inside containment (approximately 500); 22 splices, including those found by the NRC reviewer, were found to be deficient.

These 22 splices will be reworked to conform to the vendor's installation instructions. Ten other splices require further evaluation. Other safety-related cable-to-cable terminations (splices) will also be reviewed. Any splices found to be deficient in this review will be reworked to conform to the vendor's installation instructions.

This item has been reported to the NRC pursuant to 10CFR50.55(e).

2. Concern: The reviewer inspected the safety injection (SI) and containment spray (CS) pumps and found Class lE cables and non-Class 1E cables entering the same motor junction box on each of these pumps. It was explained to the reviewer that the non-Class lE cable was connected to a Resistance Temperature Detector (RTD), and this is a low energy circuit which cannot affect the Class 1E cable. The reviewer was concerned with this response and asked for more information.

l l Response: Calculation EC-5060, Rev. 1, Low Energy Circuit Analysis,

discusses RTDs in Section H of Part 3.0. 600 V rated cables j consisting of shielded twisted triads connect RTDs to signal i conditioners. Signal conditioners use wheatstone bridges, of l which the RTD is one leg, driven by a power supply. Due to the

' wheatstone bridge's inherent configuration and operating characteristics, a fault in the RTD cable is limited to values almost identical to normal operating currents. This current was calculated in EC-5060 and is approximately 20 ma. RTD circuits are therefore low energy and cannot affect other cables in their vicinity.

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Attachment 1 ST-HL-AE-1950 Page 2 of 8

3. Concern: Upon touring the ESF pump rooms in the Fuel Handling Building (FHB), the reviewer noted that the pump tags were not color-coded to indicate the associated trains (A, B or C) similar to the designations which exist in the cable spreading areas or switchgear rooms.

Response: Unlike cable trays, switchgear and other electrical equipment, which are color-coded per the requirements of IEEE 384-1974, mechanical equipment, such as safety injection or containment spray pumps, does not have color-coded tags or markings which indicate specific train orientation during construction. STP has developed a procedure for equipment labeling that will be implemented by the plant operations department.

This procedure will ensure that valves, major components and instrumentation are permanently labeled with an identifying tag or plate to provide operators and maintenance personnel with sufficient information for positive identification.

The identifying labels for major equipment such as pumps, compressors, etc., will be attached to a structural member of the equipment and will include the unit number, component number, component description (i.e., Component Cooling Pump 1A) and the power supply to the component (i.e., MCC 1G3 Cubicle 4).

The procedure will require the following:

Equipment (including electrical parts of mechanical components), room, and valve labels shall be made of stainless steel when used inside the Reactor Containment Building.

Aluminum labels used outside the Reactor Containment Building shall be color coded as follows depending on system or use.

Color System /Use Stainless Steel All systems and components in the Reactor Containment Building (not color coded) l l

Violet Safety Train A (outside containment) l Brown Safety Train B (outside containment)

Grey Safety Train C (outside containment) i Black Breathing Air l Ll\nrc\qy.

Attrchment 1 ST-HL-AE-1950 Page 3 of 8 Dark Red Fire Protection Gold Systems / components under Chemical Operations control. (not assigned specific color)

Dark Green Systems / components under Reactor Operations control. (not assigned specific color)

Blue Systems / components under Chemical Analysis control.

Tan Systems / components under Health and Safety Services control.

Electrical equipment (panels, switchgear, etc; not including electrical parts of mechanical components, such as pump motors and motor operated valve actuators) shall have labels with a colored background according to the following color scheme (FSAR Section 8.3.1.3):

Color System /Use Red Class lE equipment related to ESF Train A, 125 VDC Train A, 125 VDC Channel I and PAM 1. (Red may be replaced by violet for cables and equipment tags)

Blue Class 1E equipment related to ESF Train B, 125 VDC Train B and 120 VAC Channel III. (Blue may be replaced by brown for cables and equipment tags)

Yellow Class 1E equipment related to ESF Train C, 125 VDC Train C, 120 VAC Channel IV and PAM 2. (Yellow may be replaced by grey for cables and equipment tags)

White 125 VDC Train D and 120 VAC Channel II Orange Reactor trip and ESF actuation Train "R" Ll\nrc\qy,

Attcchment 1 ST-HL-AE-1950 Page 4 of 8 Green Reactor trip and ESF actuation Train "S" Black All non-Class lE equipment-Equipment in the FHB had'not yet been labelled at the time of the NRC site visit (week of January 26, 1987), but labeling has subsequently been completed.

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i 4. Concern: The NRC reviewer stated that the electrolyte level indications on the DC battery cells should be marked "high" and " low".

1 Response: Each battery has only 2 level indications _(upper and lower).

Although the indications are not identified specifically as "high" and " low", they are placed conspicuously on each battery. The STP Technical Specifications (Chapter 3/4.8.2, "D.C. Sources") require that the electrolyte levels in each battery be verified to be within the appropriate range. This verification occurs every seven days.

A station procedure has been developed for the 7 day surveillance test of the 125 Volt class lE batteries. This procedure specifically states (as acceptance criteria) that the electrolyte level is to be above the bottom line and less than 1/4" above the top line. The data sheet, which must be com-pleted per the procedure, also refers to the " top line" and

" bottom line".

It is STP's position that the battery cells are marked l sufficiently to enable proper maintenance of the electrolyte levels per the procedure and, therefore, do not need to be l

further identified by labels (or other means) which state "high" and " low".

5. Concern: The reviewer expressed a concern regarding electrical l penetration protection devices. It was observed that in some cases, credit was being taken for a control power transformer (CPT) as the " backup protection device". The reviewer requested more information on this matter.

, Response: In the response to Question 430.21N of the STP FSAR, the protection of electrical penetration conductors is discussed in detail. A discussion concerning CPT's is in part 6 of the response to Question 430.21N.

! In NUREG-0781, the Safety Evaluation Report (SER) for STP, l'

Section 8.3.3.5 contained an open item concerning maximum available fault current at electrical penetrations. Houston Ll\nrc\qy.

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Attcchment 1-ST-HL-AE-1950 Page 5 of 8 Lighting & Power Company (HL&P) submitted the requested information for this item by letter ST-HL-AE-1687, dated June 11, 1986. In Supplement No. 1 to the SER, the NRC staff concluded "...that the STP design provides independent primary and backup fault protection, for each penetration conductor, to preclude a single failure from impairing the integrity of a containment electrical penetration. This meets the require-ments of GDC 50 and the guidancs of Regulatory Guide 1.63 and is, therefore, acceptable."

6. Concern: While inspecting the ESF electrical control panel (ZCP-003),

the reviewer questioned why STP did not have a dedicated "DG Out for Maintenance" alarm window in the bypass / inoperable window box.

Response: The South Texas Project control room design provides one system to indicate the status of all the ESF systems and components, including the emergency diesel generators. This ESF Status Monitoring System is described in Section 7.5.4 of the STP FSAR and 7.5.1.3 of the SER (NUREG-0781). One portion of this system performs the bypass / inoperable status monitoring (BYP/INOP) function sud is specifically designed to meet RG 1.47 and BTP ICSB-21.

The bypass / inoperable status monitoring function provides:

1. Visual indication (through lampbox lights) that specific ESF equipment has been bypassed or deliberately rendered inoperable during normal plant operating modes.

2. Annunciation to alert the operator that an ESF system or any of its support systems has been bypassed or deliberately rendered inoperable during normal plant operating modes.

The component BYP/INOP windows are arranged by system to facilitate monitoring of the safety system status and determination whether continued reactor operation is permissible by the operator. In addition to the windows provided to automatically monitor specific components which may render an ESF system inoperable, the capability to manually initiate BYP/INOP indication is provided. This capability is administrative 1y controlled and used when a component is taken out of service for maintenance.

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Attcchment 1 ST-HL-AE-1950 Page 6 of 8 The BYP/INOP windows are physically separated from the ESF status monitoring fail-to-actuate windows within the lampbox for each system. The arrangement for ESF Bus A is shown in Attachment 2. In addition, the BYP/INOP windows are white when illuminated, while the fail-to-actuate windows are red when illuminated.

When any component level BYP/INOP window is illuminated, a larger system level window engraved "BYP/INOP" is also illuminated and an audible warning is provided.

When a DG is to be taken out for maintenance, the control room operators will approve this action and could then manually activate the BYP/INOP window. In addition, the manner in which the DG is taken into a maintenance condition will also light individual windows (and the system level window, if not already-lit). These additional conditions include control transfer switch not in the remote position and loss of control power.

The South Texas Project position is that the ESF Status Monitoring System meets the requirements of BTP PSB-2 " Criteria-for Alarms and Indications Associated with Diesel-Generator Unit Bypassed and Inoperable Status". This position is rupported by the STP Safety Evaluation Report (NUREG-0781, det.ed April 1986), Section 8.3.1, pages 8-8 and 8-9 which state:

"The staff reviewed the diesel generator alarm and status (bypass or inoperability) information provided for the control room operator. The bypass or inoperability status of each standby diesel generator is automatically indicated in the control room through the ESF status monitoring system. The.FSAR identifies a number of conditions that will render the diesel generator incapable of responding to an automatic emergency start signal. These conditions are alarmed through the ESF status monitoring system, and each condition has its individual alarm windows. These conditions are limited to those within the diesel generator system itself. The staff finds the alarming of inoperable conditions within the diesel generator system acceptable."

Therefore, no additional "DG Out for Maintenance" alarm window is needed in the STP control room.

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Attcchment 1 ST-HL-AE-1950 Page 7 of_8

7. Concern: While inspecting the ESF systems control panels in the STP control room, the reviewer indicated that redundant valve position indication for the safety injection system accumulator discharge isolation valves should function continuously. He did not consider the STP design as adequate since the set of indication powered by the normal valve control circuit is deenergized when the power lockout is actuated.

Response: Redundant valve position indication is provided for the accumulator discharge isolation valves. In the STP design, one

, set of indicating lights is operated by limit switches within the motorized valve operator, powered from the 120VAC valve control circuit. The redundant set of indicating lights is 1-operated by sten-mounted limit switches on the valve, powered from the 120VAC power lockout control circuit. Therefore, two j different power sources are used although of the same safety ,

train.

[ The redundant position indications for these valvos are functional whenever the valve actuator has power available.

Administrative controls require that the valve position be verified correct for the plant condition prior to removing power from the actuator. On the basis stated in BTP ICSB-18 that no single failure can reasonably restore power to the actuator and cause mechanical motion of the valve, there is no need for redundant position indication when power is locked ,

out. Since the valve position is verified correct prior to -

locking out power, the valve position cannot change 4- (electrically) while power is locked out, and a spurious

reapplication of power will not cause the valve to reposition, there is no safety concern for the accuracy of indicated <

, position while power is locked out. Actual position can always j be confirmed by temporary reapplication of power.

In addition to the redundant Class 1E position indications, non-Class 1E computer indication, annunciation, and

{ bypass / inoperable status monitoring are provided for these '

valves. An annunciator window is provided for each valve, with an audible and visual alarm in the control room when RCS l pressure is above the P-11 SI reinstatement setpoint and that l valve is not fully open, as sensed by either the MOV limit

switch or stem mounted limit switch. This alarm is reflashed

on approximately an hourly basis while the valve is abnormally positioned. A BYP/INOP alarm for each safety injection train is provided through the ESF Status Monitoring System when that train's accumulator discharge isolation valve is not fully f

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Att:chment 1 ST-HL-AE-1950 <

Page 8 of 8  !

( open. Position of these valves is also displayed on an SI system graphic in the ERFDADS computer. These alarms and indications function independently of the power lockout status of the valves.

The power lockout design is discussed in Sections 7.6.3 and 6.3.5.5.1 of the STP FSAR and in the responses to NRC questions 032.32, 430.18N, and 430.107N. Power lockout valves were also discussed with the NRC staff during the ICSB meeting in March

of 1985 (refer to Reference A, Item 21). Logics and schematics were reviewed in detail at that time. The STP Safety Evaluation Report subsequently states

"There are two sets of valve position indicating lights on the main control board. One set of lights is operated by

, a valve motor limit switch, and the other set is actuated by a valve stem;1imit switch. The valve stem limit switch lights are powered by a separate Class lE power supply that will not be affected by the removal of power from the valve motor circuit breakers. An alarm will sound when either of the limit switches senses that the valve is not fully open. The staff finds that the design conforms to BTP ICSB-4 and is acceptable."

(Refer to NUREG-0781, dated April 1986, Section 7.6.2.2, page 7-39).

It is therefore the STP position that no changes to these valve position indication circuits are necessary.

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' l Attachment 2 '

ST-HL-AE-1950 l Page 1 of 1 l

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1 ESF STATUS MONITORING LAMPBOX l ARRANGEMENT FOR ESF BUS A

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