ML20203K258
| ML20203K258 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/31/1986 |
| From: | Opeka J NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | Thadani A Office of Nuclear Reactor Regulation |
| References | |
| TASK-1.D.2, TASK-TM A02959, A05577, A2959, A5577, TAC-51257, NUDOCS 8608070133 | |
| Download: ML20203K258 (5) | |
Text
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July 31,1986 Docket No. 50-336 A02959 A05577 Office of Nuclear Reactor Regulation Attn:
Mr. Ashok C. Thadani, Director PWR Project Directorate #8 Division of PWR Licensing - B U.S Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:
Millstone Nuclear Power Station, Unit No. 2 Safety Parameter Display System In a letter dated February 11,1986(l), the NRC Staff requested that Northeast Nuclear Energy Company (NNECO) provide additional information on the Safety Parameter Display Systpp (SPDS) beyond that already forwarded in our letter dated March 25, 1985.W In accordance with that request, NNECO hereby provides the attached information.
Should you have any further questions, please contact us.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY hb
- 3. F. OpikA O
Senior Vice President (1)
A. C. Thadani letter to 3. F. Opeka, dated February 11,1986.
(2)
W. G. Counsil letter to 3. R. Miller, dated March 25, 1985.
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Attachment Millstone Nuclear Power Station, Unit No. 2 Safety Parameter Display System Additional Information July,1986
d MILLSTONE NUCLEAR POWER STATION, UNIT NO' 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION SAFETY PARAMETER DISPLAY SYSTEM General Information:
The Safety Parameter Display System (SPDS) at Millstone Unit No. 2 is part of the plant process computer. All existing safety-related instruments are isolated from the plant computer as discussed in the Millstone Unit No. 2 FSAR, Section 7.
All new safety-related SPDS inputs are to be isolated using the Foxboro SPEC 200 Model N-2A0-VAI and Energy Incorporated Model 00993 Class IE electrical isolation devices.
Specific Information:
a.
For the type of device used to accomplish electrical isolation, describe the specific testing performed to demonstrate that the device is acceptable for its application (s). This description should include elementary diagrams when necessary to indicate the test configuration and how the maximum credible faults were applied to the devices.
Response
Both the Foxboro SPEC 200 and the Energy Incorporated Class IE electrical isolation devices were tested in a similar manner. The devices were set up for normal operating conditions with either a digital voltmeter or a strip chart recorder connected to the input. A series of fault conditions were then applied to the output while the input was observed on the test equipment.
The series of conditions included open circuit, short circuit, and test voltages.
The test results revealed that sufficient isolation was maintained when the test faults were applied.
Foxboro isolation devices of the same design were used l
for the SPDS at Millstone Unit No. 3.
These devices and their testing were evaluated by the NRC Staff and judged to be acceptable and in conformance with NUREG-0737, Supplement I as documented in NUREG-1031, Supplement 4, " Safety Evaluation Report Related to the Operation of Millstone Nuclear Power Station, Unit No. 3", November 1985.
The testing of the Energy Incorporated Class IE isolation devices is documented in the following report:
i Qualification Report for Energy incorporated Series 00993 Class IE Single Channel Encapsulated Isolator EIP-QR-001 Rev. 2 l
.. This report is designated as El proprietary and therefore has not been provided with this submittal.
However, this report is available in our files for inspection at any time.
b.
Data to verify that the maximum credible faults applied during the test were maximum voltage / current to which the device could be exposed, and define how the maximum voltage / current was determined.
Response
The instrumentation cables at Millstone Unit No. 2 are separated from all high voltage cables, as discussed in FSAR Section 8.7.2.
Taking this into account, the maximum credible voltage fault the iso!ators could be subjected to is 120 volts AC and 125 volts DC. The voltages and faults applied during the isolator testing meet or exceed all credible events.
c.
Data to verify that the maximum credible fault was applied to the output of the device in the transverse mode (between signal and return) and other faults were considered (i.e., open and short circuits).
Response
The Foxboro SPEC 200 and the Energy Incorporated Class IE electricalisolation devices were both tcsted in the transverse mode. Qualification details of this test and other faults are documented in the following reports:
Foxboro Test Report Nos.
QOAAA20 QOAAB17 Energy Inc. Test Report Nos.
EIP-QR-001 Rev. 2 d.
Define the pass / fail acceptance criteria for each type of device.
Response
The pass / fail acceptance criteria require that no credible failure at the output of an isolation device prevent the associated protection system channel from meeting the minimum performance requirements as specified in the design basis, Provide a commitment that the isolation devices comply with the e.
environment qualifications (10 CFR 50.49) and with the seismic qualifications which were the basis for plant licensing.
Response
The isolation devices are located in a mild environment and, as such, are not subjected to the requirements of 10CFR50.49.
Nonetheless, the isolation devices are
w o environmentally qualified in accordance with IEEE 323-1974 for use in a mild environment. These devices are also seismically qualified in accordance with IEEE 344-1975 standards. A review of the test results indicates that the isolators comply with the Millstone Unit No. 2 seismic design basis, f.
Provide a description of the measures taken to protect the safety systems from electrical interference (i.e., Electrostatic Coupling, EMI, Common Mode and Crosstalk) that may be generated by the SPDS.
Response
Safety-related systems are protected from electrical interference using the following methods:
1)
Instrumentation and power cables are physically separated, 2)
Instrumentation cables use twisted and shielded conductors, and 3)
The shield is grounded at a single point.
g.
Provide information to verify that the Class IE isolator is powered from a Class IE power source.
Response
The Class IE instruments are powered by four physically isolated and electrically independent safety-related inverters.
All equipment in the instrument loop, including the isolators, are powered from the same source.
L..