ML20212M414

Forwards Addl Info Re Electrical Isolation Devices (SER Open Item 7) & Class 1E/non-Class 1E Control Circuit Interfaces (SER Confirmatory Item 16),per 870113 Request.Smoke Detector Configuration Acceptable.W/Five Oversize Drawings

ML20212M414
Person / Time
Site:	South Texas
Issue date:	02/19/1987
From:	Wisenburg M HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20212M416	List: ML20212M414 ML20212M420 ML20212M425 ML20212M447 ML20212M477 ML20212M492 ML20212M591 ML20266D945 ML20266D949 ML20266D954 ST-HL-AE-1917, Marked-up Schematic Diagram - Relay Logic. Sheet 2 of 5
References
ST-HL-AE-1917, NUDOCS 8703120008
Download: ML20212M414 (12)

Text

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The Light NE f Ilouston Lighting & Power P.O. Box 1700 llouston, Texas 77001 (713) 228-9211 February 19, 1987 ST-HL-AE-1917 File No.: C9.15, J41.3, J9, J28 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 Additional Information Concerning Electrical Isolation Devices and Class 1E/Non-Class lE Control Circuit Interfaces During a conference call on December 1, 1986, the NRC staff raised several questions concerning electrical isolation devices (SER Open Item #7) and non-Class lE control signals interfacing with Class 1E control circuits (SER Confirmatory Item #16). Subsequently, by letter dated January 13, 1987, the NRC staff submitted a Request for Additional Information (RAI) relative to several of these issues.

Attachment 1 to this letter provides responses to the questions concerning electrical isolation devices. This information was provided informally to the NRC staff during the audits at the STP site on January 28-30, 1987.

During those audits, questions were raised concerning Magnetics current transformers and Struthers-Dunn relays used as isolation devices in main control panel CP-003. Responses to these questions are contained in the next two paragraphs.

The Magnetics current transformers were previously discussed with the NRC staff during the ICSB meeting in March, 1985. See Attachment 16 for reference to the meeting minutes. As this was not identified as a concern in the SER, we believed that the issue was closed.

Struthers-Dunn relays were qualified as Class lE devices in accordance with IEEE 323-1974, IEEE 344-1975, and the test report provided as Attachment

12. This testing includes a dielectric strength test at 2200 Vac. In addition, a surge withstand test was performed at 2500 V, 1 Mllz, in accordance with ANSI /IEEE C37.90-1978 and IEEE 472-1974; the test report is provided as Attachment 13. The surge potential was applied in both the commot. and transverse modes.

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. Houston Lighting & Power Company -File No.: G9.15, J41.3, J9, J28L Page-21 J

.The'following five paragraphs address the questions regarding Confirmatory Item 16 in the subject RAI.

-Attachment 14 is a copy of HL&P letter ST-HL-AE-1840, dated December 9, 1986 which transmitted Revision 4 to the Component Cooling Water Pump Logic ' l Diagram,' drawing SR20-9-Z42040. An additional copy of the drawing is provided .l

.as Attachment-17. l 1

.. lThe 10CFR50.55(e) report concerning Potential' Failure of Non-Seismic CCW:

-Tank Level and Flow Switches was submitted by HL&P. letter ST-HL-AE-1691, dated July 22, 1986. A copy of this revised final report is provided as Attachment' )

22.  !

-Regarding the non-Class 1E toxic gas and smoke detector control signals

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interfacing with Class 1E. control circuits,-on December 19, 1986, HL&P reported a deficiency pursuant to 10CFR50.55(e) concerning the failure mode of the toxic gas detectors at STP. ,

A copy of this report is included as Attachment 15. The toxic gas detectors are required to function to isolate the control room ventilation system, in the event of a toxic gas release, to protect the operators from injury. The actuation circuitry is.being modified such that a failure of the toxic gas detectors will initiate isolation, thus performing the protective function.

HL&P has evaluated the similar application of smoke detectors and 4 determined that their configuration was acceptable. Unlike a toxic gas ,

t release, smoke entering the control room ventilation system is easily

' detectable by the operators. Manual isolation of the ventilation system will prevent operator injury or loss of habitability within the control room.

. Therefore, no change is required to the smoke detector circuitry.

The information provided above and previously submitted should be adequate to resolve any remaining NRC staff concerns relative to electrical isolation' devices and non-Class lE interfaces with Class lE control circuits.

If you should have any further questions on this matter, please contact S

l, Mr. M. E. Powell at (713) 993-1328.

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s M. R. ise urg i Deputy Proj ct Manager THC/yd Attachments: 1. Responses to NRC questions (Reference E) concerning  !

electrical isolators (SER Open Item #7).

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2. STP-704: Energy Incorporated ~ Test Procedure for_ .

Performance and-Isolation Testing of 1E Analog and Digital

' Isolators (also'EIP-24).  !

3 ~. ~EIP-37: Energy. Incorporated Integrated Test: Procedure

'for Analog and Digital Isolation System, including Design Basis System Fault Testing.

4. -EIP-TR013: Energy Incorporated Test. Report on Eight-Channel Digital Isolator.

5. Cooper Energy Systems Diesel Generator Isolator, Wyle Laboratories Report.No. 57719 - Electrical Test Report on Isolation Relays and Transmitter and Receiver for.Bechtel.

Energy.

~ 6. Sorrento Electronics Letter ST-DW-YB-509, dated January l

21, 1987, concerning Seabrook Isolators.

7. Sorrento Electronics Letter ST-DW-YB-511 dated-January 21, 1987, concerning Hope Creek and River Bend Isolators.

8. ERFDADS Isolation System Block Diagram and Schematics.

9. Sorrento Electronics Letter ST-DW-YB-515, dated January 122, 1987, concerning Radiation Monitoring System

Isolator's Immunity to Electromagnetic Interference (EMI).

l 10. Cooper Energy Systems Diesel Generator Control Panel Isolator Block Diagram and Schematics.

1 11. Radiation Monitoring System Communications Isolation

Device Schematic.

l 12. SPD#328: Struthers-Dunn Relay Qualification Testing Procedure,

13. Wyle Report on Surge Withstand Testing of Struthers-Dunn Relays, Bechtel Log #14926-4304-00776-AMD.

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14. Responses to NRC Staff Questions regarding Review of the i Component Cooling Water Pump Logic Diagrams; M. R.

Wisenburg, HL&P, Letter to Vincent S. Noonan, NRC; dated

' December 9, 1986; ST-HL-AE-1840.

15. Final Report concerning Toxic Gas Detectors; J. H.

Goldberg, HL&P, Letter to U.S. NRC; dated January 20,

1987; ST-HL-AE-1885.

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ST-HL-AE-1917'

. Houston I.ightmg & Po , -r Company - File No. : - G9.15, J41.3, J9, J28 Page 4

~ 16. . References to Previous STP Correspondence concerning Electrical Isolation Devices.

17. Component Cooling Water Pump Logic Diagram, Bechtel Drawing SR20-9-Z42040, Rev. 4.

18. Diesel Cenerator Control Cabinet Assembly, Cooper Energy

-Systems Drawing, annotated to'show location of isolator transmitter and receiver cards, Bechtel Log

^#14926-4041-00051-FCE.

19. Digital Communication Interconnection, Sorrento-Electronics Drawing, annotated to'show Communications Isolation Device power sources, Bechtel Log

1. 14926-4301-00098-CDW.

20. Schematic Diagram - Relay _ Logic, Sorrento Electronics Drawing annotated to show Emergency Operation actuation logic power sources, Bechtel Log #14926-4301-00084-CDW.

21. Schematic - PORV Isolation Box, Sorrento Electronics Drawing, annotated to show'the PORV position input isolation device power source and radiation monitor power sources for the isolator output logic, Bechtel Log ,

1. 14926-4301-00293-ADW.

22. Revised Final Report Concerning Potential Failure of Non-Seismic CCW Tank Level and Flow Switches; J. H.

Coldberg, HL&P, Letter to Robert D. Martin, NRC; dated July 22, 1986; ST-HL-AE-1691.

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1ST-HL-AE-1917

Filo N3.:: G9.15, J41.3, J9, J28

. Houston Lighting & Power Company Page 5 cc:

. Regional' Administrator, Region IV :M.B. La'e/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

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• i N. ' Prasad Kadambi, - Project Manager . M.T. Hardt/A.Lvon Rosenberg

.U.S.:. Nuclear Regulatory Commission' City Public Fervice Bot.rd 7920 Norfolk Avenue- ,P.O. Box 1771-Bethesda,- MD : 20814 San Antonio -TX 78296 i e . 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 .

I*- 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. 0.-Box 2121 Corpus Christi, TX 78403

• With Attachments 1 through 22; all others with Attachment 1 only.

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', l' Attachment -'l' Responses.to'NRC Questions (Reference E)'Concerning Electrical Isolators (SER Open Item #7)

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-Attcchment 1.

ST-HL-AE-1917 File.No.: G9.15, J41.3, J9, J28

_Page 1 of 4 Responses'to'NRC Question Concerning Electrical Isolators Note: These questions were raised by Reference E as listed in Attachment 16.

.1. _Q uestion: The applicant'should forward information regarding the EI test ~ ,

-report on the digital isolators, Model 01026-17.

Response

The'information requested is contained in Attachments 2 through 4.

Please note that the digital isolator part number shown on Page 7 of our original response (Reference D) should be 01026-13 in lieu of 01026-17,

2. Question: The applicant should forward information regarding the Cooper Energy Systems test report on their digital isolators. The test report should give the details of the maximum _ credible fault testing and the Class 1E to non-Class lE interfaces.

Response

The test report for the Cooper Energy Systems isolator is included as Attachment 5. However, as noted in our original response, fault testing was not performed due to the physical separation between the transmitter and receiver. The transmitter and receiver cards are separated by 2-1/2 feet and are connected by an 8-foot fiber optic cable. The energy released by a failure on an output card (receiver) cannot affect an input card (transmitter). .The layout of the transmitter and receiver cards is shown in Attachment 18. This arrangement was inspected by members of the NRC staff during the audits at the STP site on January 28-30, 1987.

3. Question: The applicant should check their CA DRMS isolation modules and provide information that reassures the staff that the modules are the same as those used by Hope Creek and River Bend and are not the same as those used by Seabrook.

Response

The isolation modules on STP are the same as those used by Hope Creek and River Bend. The STP isolation modules are not the same as those used by Seabrook, where a fuse and transorb were provided as an isolation device.

Attachments 6 and 7 contains Sorrento Electronics letters that substantiate the above.

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IAttachment 1-ST-HL-AE-1917 1 . -

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" . File No.: G9.15', J41.3',' J9, J28 Page 2 of 4

4. _The applicant;should' provide' responses to the following-questions "f" and "g":

. Question f. Provide a description of the measures taken to protect- ,

the safety systemsufrom electrical interference (i.e.,

Electrostatic Coupling.. Electromagnetic Interference,,

Common Mode Signals) that may be generated as a result of using the electrical isolators.

1 Response:.

-Emergency Response Facilities Data Acquisition and Display System (ERFDADS) Isolators Safety systems connected to ERFDADS isolators are protected from electrical' interference by physical location of equipment, grounding provisions and interconnections via. shielded cables. A block diagram of.

this arrangement is provided as Attachment 8.

The major potential source of electrical interference generated by ERFDADS at the location of the-Class lE' connections is the multiplexing equiment, since the computer is linked via a fiber optic cable and is a minimum distance of 50 feet away. This equipment is located in the

- multiplexer cabinet, which is separate from the isolation / termination cabinets. This arrangement provides two metal shell cabinets, ' esc *n

. grounded for shielding of electrostatic and EMI coupling,_between the potential noise source and the Class 1E connections. All connections between these cabinets are made via shielded twisted pair wiring to alleviate any noise coupling in the wire runs. Common mode coupling and crosstalk of the digital signals are avoided by the use of opto-isolators in the multiplexer cabinet and the'1E isolators in the isolator cabinets.

Each analog signal has its own separate twisted pair for transmission

'from the Class 1E isolator to the multiplexer cabinet. Each signal is multiplexed through standardized equipment with a very high crosstalk rejection ratio. The Class lE isolators were type tested for crosstalk effects by Energy Incorporated test procedure STP-704 (Attachment 2).

Both digital and analog isolators guarantee that no effect at the output will be propagated to the input with sufficient energy to damage connected Class 1E components, or to cause false indication on another channel.

Radiation Monitoring System Isolators The safety related functions of the Radiation Monitoring System will not be affected by EMI in the vicinity of the isolators based on the Sorrento Electronics discussion provided in Attachment 9.

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t Att chment'1 ST-HL-AE-1917

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' File No.: G9.15, J41.3, J9,-J28 4

.Page 3 of 4

Diesel Generator Control Isolators:

The safety- related functions 'of the Diesel Generator System will not be

affected by EMIsin the vicinity.of the isolation system. Esis statement

~is based'on the following:

The isolation' system is enclosed in a 3/16" thick

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steel cabinet which is' grounded to-the station ground.

2._ The fiber optic transmitter. requires at least 12 milliamps-at 125 volts DC to turn on.

In addition,. control circuit interface with the fiber optic isolation system is such that,no failure will affect the operation of~the standby diesel generators when they:are operating in the emergency mode.

A block diagram and schematics of.the transmitter and> receiver cards are provided as Attachment 10. An annotated drawing of the cabinet arrangement is provided as Attachment 18.

Question: g. Provide information to verify that the Class lE isolators are powered from a Class 1E power source.

Response

ERFDADS Isolator Power-Supply A' block diagram and schematics showing how the Class IE isolators are powered are provided in Attachment 8. Class 1E power is provided to the Class 1E portions of the circuitry, including the passive side of the isolation modules. Non-Class lE power is provided to the' active, non-Class 1E output side of the isolation modules.

Radiation Monitoring System Isolator Power Supply Power corresponding to the appropriate electrical separation train is provided to each of the three types of electrical isolation devices ,wed in the Radiation Monitoring System.

Attachment 19 shows a typical application of the communications isolation device (CID). For STP, separate communications loops are used for

. monitors assigned to separation groups A, C, and N respectively.

Separation group A monitors form one communications loop; separation

, group C monitors form another loop; and separation group N (non-Class IE) monitors form three additional loops. Therefore, no safety s train to-safety train isolation is utilized in communication loops.

. Although each CID transmits data bidirectionally, one side contains passive circuitry, from an electrical standpoint, while the other side

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AttCchment 1 ST-HL-AE-1917 File No.: G9.15, J41.3, J9, J28 Page 4 of 4 contains an active loop power supply (refer-to Attachment 11). Power for the CID passive side loop is provided from the active side of the adj acent, connected assembly. ' Power for the CID active side loop is provided from the CID power supply, which also drives the passive side of the adjacent connected assembly.

-A typical schematic diagram for relay logic used for emergency damper actuation is provided as Attachment 20. Power for each safety-related radiation monitor and the actuation logic within its train corresponds to the separation group assigned to that monitor. Power for the actuation logic for other safety trains is provided from each of those separation groups, respectively.

The PORV isolation box schematic diagram is provided as Attachment 21.

This device provides Class 1E to Class lE isolation between two safety trains. Power for the steam generator PORV limit switch and isolation device input is provided from the safety train associated with the respective PORV. Power for the isolation device output is provided from the +24 VDC Class lE power supply in the radiation monitor which receives

'the PORV position signal.

Diesel Generator Control Panel Isolator Power Supply A block diagram and schematics showing how the Class lE isolator is powered are included as Attachment 10. Class lE power is provided'to the transmitter card, while non Class lE power is provided to the receiver card.

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v-Attachment 2-STP-074: Energy Incorporated Test-Procedure for Performance and Isolation Testing of IE Analog.and Digital Isolators (also EIP-24)

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