ML20092J856
| ML20092J856 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 06/20/1984 |
| From: | Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE, YANKEE ATOMIC ELECTRIC CO. |
| To: | Knighton G Office of Nuclear Reactor Regulation |
| References | |
| SBN-671, NUDOCS 8406270155 | |
| Download: ML20092J856 (5) | |
Text
.
SEABROM STAHON Lj PUBLIC SERVICE Engin ana omee:
Company of New Han-npshre 1671 Worcester Road Framinchom. Mossochusetti 01701 (617) - 872 - 8100 June 20, 1984
':YN-r, ; 1 T.F. B7.1.2 United States Nuc lea r Regulatory Commission Wa s hi ng t on,
D.
C.
20555 Attention:
Mr. Ge o rg e W. Knighton, Chief Licensing Branch No. 3 Division of Licensi ng
References:
(a) Construc t @n Permi ts CPPR-13 5 and CPPR-136, Docket No s. 5 0-4'1D and 50-444 (b) PSNH Letter SBN-427, dated January 20, 1983, "Open Item Re s pons e s", J. De Vi nc en t i s to G.
Knighton (c)
PSNH Letter SBN-587, dated December 1, 1983, " Electrical In t e rconnec t io ns Be tween Re du nda n t Divisions",
J.
DeVincentis to G.
Knighton
Subject:
Elect rical Inte rconnec t ions Be tw ee n Re du nda n t Di visi on s
Dear Sir:
Reference (c) transmitted the results of a study performed to identify any cables be t wee n redundant divisions whe re physical separation is not fully in accordance with the criteria established in the FSAR.
Identified deviations and proposed cor rec tive actions were also documented as part o f t he study.
At the time of the submittal, the analysis of Item 10 of the study, pe rtaining to the compute r In telligence Remote Te rminal Units (I RTL' )
1, 2, 4, and 6 had not been completed. We had indicated in Reference (c) that the result of this analysis will Le submit ted as soon as they become available.
The analysis is now complete and is forwarded herewith for your review.
Very truly yours, Y ANKEE ATOMIC ELECTRIC COMPANY J
ru Jo hn DeVincentis Enginee ring Ma nager cc: Atomic Safety and Licensing Boa rd Service List
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i A
William S. Jordan, III, Esquire Brentwood Board of Selectmen Harmon & Weiss RED Dalton Road 1725 I Street, N.W. Suite 506 Brentwood, New Hampshire 03833 Washington, DC 20006 Roy P. Letsy, Jr., Esquire Office of the Executive Legal Director Edward F. Meany U.S. Nuclear Regulatory Commission Designated Representative of Washingtor DC 20555 the Town of Rye 155 Washington Road Robsrt A. Backus Esquire Rye, NH 03870 116 Lowell Street P.O. Box 516 Calvin A. Canney Mancehster, NH 03105 City Manager City Hall Philip Ahrens, Esquire 126 Daniel Street Assistant Attorney General Portsmouth, NH 03801 D2partment of the Attorney General Augusta, ME 04333 Dana Bisbee, Esquire Assistant Attorney General Mr. John B. Tanzer Office of the Attorney General Designated Representative of 208 State House Annex the Town of Hampton Concord, NH 03301 5 Morningside Drive H:mpton, NH 03842 Anne Verge, Chairperson Board of Selectmen Roberta C. Fevear Town Hall Designated Representative of South Hampton, NH 03842 tha Town of Hampton Falls Drinkwater Road Patrick J. McKeon Hempton Falls, NH 03844 Selectmen's Office 10 Central Road Mrs. Sandra Cavutis Rye, NH 03570 Dasignated Representative of the Town of Kensington Carole F. Kagan, Esq.
RFD 1 Atomic Safety and Licensing Board Panel E4st Kingston, NH 03827 U.S. Nuclear Regulatory Commission Jo Ann Shotwell, Esquire Assistant Attorney General Mr. Angie Machiros Environmental Protection Bureau Chairman of the Board of Selectmen D2partment of the Attorney General Town of Newbury One Ashburton Place, 19th Floor Newbury, MA 01950 Boston, MA 02108 Town Manager's Of fice Senator Gordon J. Humphrey Town Hall - Friend Street U.S. Senate Amesbury, Ma.
01913 W:shington, DC 20510 (Attn: Tom Burack)
Senator Gordon J. Humphrey 1 Pillsbury Street Dieno P. Randall Concord, NH 03301 70 Collins Street (Attn: Herb Boynton)
SEabrook, NH 03874 Richard E. Sullivan, Mayor Donald E. Chick City Hall Town Manager Newburyport, MA 01950 Town of Exeter 10 Tront Street Exeter, NH 03833
PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE SEABROOK STATION - UNITS 1 AND 2 CABLES BETWEEN REDUNDANT SEPARATION GROUPS EOUIPMENT ANALYSIS / RECOMMENDED ITEM DESCRIPTION NODE NO.
MODIFICATION EVALUATION 10.
Computer IRTU The Separation Group B Intelligence Remote Terminal Unit (IRTU) contains IRTU 1 SC-CP-122 FD9 Separation Group A (Train A Associated)
IRTU 2 SC-CP-125 FES and Separation Group B (Train B l
IRTU 4 SC-CP-204 GYS Associated) cables.
IRTU 6 SC-CP-212 JWO The Separation Group A cables are for the scan synchronization circuits between the host computers and the IRTU. These circuits are pulse circuits operating at 30 volt maximum and are considered low power circuits, incapable of propagating the power required to damage other circuits.
The train A Associated power supply to the IRTU does not interface with Train B or Train B Associated power supplies, except through isolation devices or low power semiconductor devices.
The Separation Group B cables are for i
analog, digital, RTD, and thermocouple inputs to the IRTU, which gathers and preprocesses the information for the host computer.
The Separation Group A and Separation Group B cables and wiring are in proximity to one another inside the IRTU.
The analysis below indicates that a failure involving Train A associated circuits in an IRTU will not challenge S'paration Group B circuits.
Therefore, this deviation from the independence between separation gevups is acceptable and no modification is required.
The following is a discussion of each type of Train B Associated input.
1.
Westinzhouse Dixital Inputs These inputs to the IRTU are through a Modcomp Model 1125 Isolated Current Input Card which contains aa optically coupled LED-photo transistor and provides up to 200 volts isolation.
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l PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE SEABROOK STATION - UNITS 1 AND 2 CABLES BETWEEN REDUNDANT SEPARATION GROUPS EQUIPMENT ANALYSIS / RECOMMENDED ITEM DESCRIPTION NODE NO.
MODIFICATION EVALUATION l
In addition, all inputs to the IRTU are protected by surge suppression equipment (varistors for digitals inputs and transorbs for analog inputs) located in the i
IRTU termination cabinet.
Further, all of these circuits are very low power circuits which are protected by a variety of fuses, circuit breakers and current / voltage limiting devices.
These protective measure will prevent propagation of failure from one separation group to another.
2.
Other Dixital Inputs i
These inputs are isolated field contacts that are scanned by monitoring the voltage applied to the contacts by the IRTU. The inputs ara not isolated from their Train A t
Associated power supply; however, they are electrically separate from other Train B
[
and Train B Associated circuits.
Additional protection is provided as noted in the second paragraph of #1 above)
Westinghouse Digital Inputs 3.
Analon Inputs For these inputs isolation credit can be claimed by the following design features:
a.
The analog multiplexer selects only one input at a time; hence, the Train A Associated and Train B Associated inputs do not connect directly to each
- other, b.
There is isolation in the wide range analog input subsystem between the scanning analog to digital (A/D) conversion circuitry and the computer interface point. This isolation is in the form of an isolating transformer; hence, there is no electrical connection between the computer i
circuitry and the wide range analog subsystem circuitry.
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PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE SEABROOK STATION - UNITS 1 AND 2 CABLES BETWEEN REDUNDANT SEPARATION GROUPS EQUIPMENT ANALYSIS / RECOMMENDED ITEM DESCRIPTION NODE NO.
MODIFICATION EVALUATION c.
The multiplexing A/D Conversion module is powered by a Train A Associated power cource. However, this module is a very low power microelectronic semiconductor unit which is incapable i
of propagating the power required to i
damage other circuits. The power to this module comes from an internal low voltage power supply, which includes an isolating transformer. This transformer acts as a barrier between Train A Associated power supply and the internal circuitry of the module.
Additional protection is provided as noted in the second paragraph of #1 above, Westinghouse Digital Inputs i
4.
Thermocouples Inputs i
These inputs are similar to the analog inputs with the exception that they come from electrically separate thermocouples whose circuitry does not interface with Train B Associated power supplies.
5.
RTD Inputs These inputs are similar to the analog inputs with the exception that they come from the conversion cabinets (see Item 11) and are ultimately powered from Train A Associated power supplies. The RTDs do not interface with Train B or Train B Associated power supplies.
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