ML20205Q279
| ML20205Q279 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 05/23/1986 |
| From: | Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | Noonan V Office of Nuclear Reactor Regulation |
| References | |
| SBN-1066, NUDOCS 8605280245 | |
| Download: ML20205Q279 (8) | |
Text
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SEABROOK STATION
'A Enginesring Office f,';N May 23, 1986 Put2c Service of New HampeNro SBN-1066 T.F.
B7.1.2 United States Nuclear Regulatory Commission Washington, DC 20555 Attention:
Mr. Vincent S. Noonan, Project Director PWR Project Directorate No. 5
References:
(a) Construction Permits CPPR-135 and CPPR-136, Docket Nos. 50-443 and 50-444 (b) PSNH Letter (SBN-903), dated November 27, 1985,
" Resolution of Power Systems Confirmatory Items",
J. DeVincentis to G. W. Knighton (c) PSNH Letter (SBN-1020), dated April 25, 1986,
" Resolution of Power Systems Confirmatory Items",
J. DeVincentis to V. S. Noonan
Subject:
Response to Request for Additional Information on SER Confirmatory Issue No. 25
Dear Sir:
Attached is our response to the Requests for Additional Information on the analysis and test program submitted by Reference (c) on the com-puter IRTUs and the RTD/TC Conversion Cabinets.
We trust that the attached responses are acceptable and reques t that resolution of the above referenced confirmatory issue be reflected in the next supplement to Seabrook's SER.
Very truly yours,
)
ohn DeVincentis Director of Engineering Attachment cc: Atomic Safety and Licensing Board Service List 8605280245 860523 k
PDR ADOCK 05000443 E
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l Seabrook Station Construction Field Office. P.O. Box 700 Seabrook, NH O3874
Dicn3 Curran, Esquire Calvin A. Cannsg Het1 son & Weiss City Manager 2001 S. Street N.W.
City Hall Suite 430 126 Daniel Stredt Washington, D.C.
20009 Portsmouth, NH 03801 Sherwin E. Turk, Esq.
Stephen E. Merrill, Esquire Office of the Executive Legal Director Attorney General U.S. Nuclear Regulatory Cossaission George Dana Bisbee, Esquire Tenth Floor Assistant Attorney General Washington, DC 20555 Office of the Attorney General 25 Capitol Street Robert A. Backus, Esquire Concord, MN 03301-4397 116 Lowell Street P.O. Box 516 Nr. J. P. Nadeau I
Manchester, NH 03105 Selectmen's Office 10 Central Road
]
Philip Ahrens, Esquire Eye, NH 03870 Assistant Attorney General Department of The Attorney General Mr. Angie Nachiros Statehouse Station M Chairman of the Board of Selectmen hugusta, NE 04333 Town of Newbury Newbury, MA 01950 Nrs. Sandra Cavutis Chairman, Board of Selectmen Mr. William S. Lord RFD 1 - Box 1154 Board of Selectmen Kennsington, NH 03827 Town Hall - Friend Street Amesbury, MA 01913 Carol S. Sneider. Esquire Assistant Attorney General Senator Cordon J. Humphrey Department of the Attorney General 1 Pillsbury Street one Ashburton Place,19th Floor Concord, MN 03301 Boston, MA 02100 (ATTN: Herb Boynton)
Senator Cordon J. Humphrey H. Joseph Flynn, Esquire U.S. Senate Office of General Counsel Washington, DC 20510 Federal Emergency Management Agencyg (ATTN: Tom Burack) 500 C Street, SW Washington, DC 20472 Richard A. Hampe, Esq.
Hampe and McNicholas Paul McEachern, Esquire 35 Pleasant Street Matthew T. Brock, Esquire Concord, NH 03301 Shaines & NcEachern 25 Maplewood Avenue Donald I. Chick P.O. Box 360 Town Manager Portsmouth, NH 03801 Town of Exeter 10 Front Street Cary W. Holmes, Esq.
Exeter, NH 03833 Holmes & Ells 47 Winnacunnet Road i
Brentwood Board of Selectmen Hampton, NH 03841 RFD Dalton Road Brentwood, NH 03833 Mr. Ed Thomas FEMA Region I Peter J. Mathews, Mayor 442 John W. McConnack PO & Courthouse City Hall Boston, MA 02109 Newburyport MA 01950 Stanley W. Knowles, Chairman Board of Selectmen P.O. Box 710 North Hampton, NH 03862
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SBN-1066 ATTACHMENT 1 RESPONSE TO REQUESTS FOR ADDITIONAL INFORMATION ON SER CONFIRMATORY ISSUE No. 25
- 1) QUESTION The " Analysis" section of the report,Section III, Page 8, takes credit for fuses, circuit breakers and other protective devices.
This invalidates the analysis.
RESPONSE
The statement on protective devices in Section III.C.2 (Page 8) was not intended to actually take credit for the protective devices preventing degradation of field devices but really was simply a statement of the circuit's response to a short circuit, i.e.,
pro-tective devices will operate. A short circuit at this point in the circuit (on the 120 volt side of the low voltage power supply) presents no potential for field device degradation because the fault current would flow directly back to the source through the short without going through the field devices.
Even if the pro-tective devices do not operate, the short circuit current would flow until some component (wire, terminal, etc.) burns open with no impact on field devices because the f ault current does not flow through the field device. Any damage to the IRTU (for example, burned open components) as a result of the short circuit or the protective devices not operating is of no concern since the IRTU performs a non-safety related f unction. Therefore, the conclusion is still valid that a short or short circuit to ground will not cause any detrimental impact on the analog input devices.
- 2) QUESTION Explain how the analysis is still valid should the optical coupler fail (Page 8).
RESPONSE
The analysis of the typical digital input applies to the optically coupled digital input shown in Figure 3 as follows:
Short Circuits and Shorts to Ground (a and c)
The analysis on Page 6 of a short circuit or short to ground on the 120 Vac input to the power supplies or within the low voltage power supplies is directly applicable since the optically coupled circuit uses the same power supplies as the typical digital input circuit.
The statement on Page 6 about components shorting is still applicable since the optical coupler is an electronic component similar to a diode. There is no credible short circuit failure mode of the optical coupler or the capacitor and diode which could result in abnormal current through the field device.
SBN 1066 Open Circuits (b)
The analysis on Page 7 of open circuits is still applicable since an open at any point within the power supply or in the optical coupler circuit including an open in the optical coupler itself will potentially disable the I0IS function but would not cause any detrimental impact on the field device.
Application of Maximum Voltage (d)
The analysis on Page 7 is applicable to the optical coupler circuit since it uses the same power supplies. This analysis involved a catastrophic f ailure within the low voltage power supply such that 120 Vac was applied to the circuits where the low voltage normally exists.
Although failure of the power supply in this manner is not very likely, and would most probably result in a short circuit and operation of a protective device, we assume the protective de-vice does not operate to add conservatism to the analysis.
With application of the 120 volts, the circuit components (resistor, diode, and capacitor) would limit the current to a low level.
Be-cause of the optical coupler, this current would not flow through the field device.
Even if the optical coupler shorts input to out-put, the current would not flow through the field device because there would be no return path.
In conclusion, the above analysis shows that a short circuit, short to ground, open circuit and application of maximum voltage will have no detrimental impact on the field devices similar to analysis on Pages 6, 7, and 8.
- 3) QUESTION If the Train "A" power and the convenience outlet power are not from the same division, explain the separation criteria invoked for these two power sources (Page 11).
RESPONSE
The power sources for the electronic's power supplies and for the convenience receptacles are f rom the same separation group (division).
- 4) QUESTION The determination and selection of the most sensitive field device (Page 14) is not acceptable.
Each different type of device used to interf ace between Train "A" power and Train "B" input signals
(
should be tested to determine their ability to stop the propaga-tion of the MCVP f rom Train " A" to Train "B".
l
/
SBN-1066
RESPONSE
The basic concept of the analysis and test program was to demon-strate that any failure within the IRTU would not have a detri-mental effect on the field input devices.
By showing this, the field devices did not have to be qualified isolators.
The analysis was discussed with and accepted by the Staff; however, they requested a test program be performed to substantiate the re-suits of the analysis.
During discussion of the test plan, the Staf f agreed that a Most Sensitive Field Device (MSFD) could be used as the test device. The MSFD would be selected by reviewing the different inputs and determining which device was most sus-ceptible to degradation (most sensitive). Using the MSFD would eliminate the need to test every field device since if the tiSFD was not degraded by the MCVF then the other devices would not have been damaged since they are less susceptible to damage.
- 5) QUESTION With respect to Figure No. 5 how are the IAV relay terminals 1 and 2 protected from the MCVF.
RESPONSE
Since the test setup was designed to simulate actual field condi-tions, no special precautions were taken to protect the IAV con-tacts.
The contacts were exposed, during the test, to the actual voltage and current they would experience in the field should a fault actually occur. The test results showed that the IAV relay contacts were not degraded.
- 6) QUESTION Provide the data that qualified the isolators mentioned on Page 21 that are used for the Westinghouse and neutron detector inputs.
RESPONSE
Westinghouse Reports WCAPs 8584, 8760, and 8892-A are applicable to the Westinghouse inputs. Thesn reports have also been refer-enced in our response to Item 5 of C-25 package attached to Refer-ence (a).
We believe that these reports have been submitted to the NRC by Westinghouse for review and approval and that they are available for the reviewer's use.
The qualification of the isolators for the neutron detector input is addressed in Gammametrics Report No. RCS-10.
The same type isola-tors and qualification report has been used in the following plants:
Millstone III, Wolf Creek, Calloway 1, Byron 1 and 2. t i.
J SBN-1066
'7)
QUESTION Are the five or so transducers listed on Page 21 non-lE devices and has their ability to degrade the Class IE bus that they are monitoring been analyzed.
RESPONSE
The five transducers listed on page 21 perform a non-lE function which is to provide an analog input to the computer. However, since the transducers interface with a Class 1E circuit, they have been seismically qualified as part of the Class IE equipment in which they are mounted as they will not degrade the Class IE circuit.
From a circuit interaction consideration, the analysis and test program have demonstrated that a failure within the computer IRTU will not degrade the Class lE circuit into which the transducers are connected.
- 8) QUESTION Integrated components IC3 and IC4 are not shown on any of the supplied figures. Their removal from the circuit under test may have created an open circuit that would not normally exist in actual operation.
RESPONSE
The integrated components referenced in the test report are IC2 and IC3 (not IC3 and IC4). These ICs are shown in the attached figure.
These components are not directly in the signal processing path so the open caused by removal of the ICs had no ef fect on the test results.
As stated in the report, reapplication of the voltage af ter the input breaker tripped and the ICs were removed is very conservative because this represents multiple faults. Voltage measurements in the signal processing path made after the test 120 Vac was removed demonstrated that the signal processing circuit was
.not damaged and that the IC removal had no effect on the signal flow path.
- 9) QUESTION Photograph No. 15 shows unprotected 120 Vac wiring adjacent to ribbon connectors and what appears to be exposed printed circuit (pc) traces.
The pc traces should be tested with the MCVF.
RESPONSE
The physical failure of wiring within the IRTU is addressed in Section III.C.3 of the report. This section concluded that physical inter-action with 120 Vac within the cabinet was not a problem.
This eval-uation was reviewed and accepted by the Staff prior to their request to perform a test program.
SBN-1066
.c The Staf f's test program request did not include any requirement to test interaction with the printed circuit (pc) board traces.
However, the test which applied the test 120 Vac to the multiplexing relay coil circuit can be used to address this concern. The ribbon cable and connectors and the pc traces supply the relay enable sig-nals to the relay coils on the multiplexing switch card (signals that pickup the relays).
Applying 120 Vac to the pc traces would actually result in 120 Vac being applied to the relay enable circuit which was the test conditions mentioned above.
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