ML20197D753
| ML20197D753 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/25/1988 |
| From: | Trzyna G COMMONWEALTH EDISON CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| 4701K, NUDOCS 8806070381 | |
| Download: ML20197D753 (4) | |
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N' Commonwealth Ediscn a
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- ) One First N:Sonal Plaza Chicago, trincis a
O J Aodress Reply to: Post Dffce Box 76I
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Chicago, litinois 60690 - 0767 v-May 25, 1988 Director of Nuclear Reactor Regulation US Nuclear Regulatory Commission Mail Scation P1-137 Washington, DC 20555
Subject:
Zion Nuclear Power Station Units 1 and 2 ATWS Protection NRC Docket Nos 50-295 and 50-304 t
References (e): July '7,1986 letter from C.E. Rossi to L.D. Butterfield transmitting the SER for WCAP-10858 (b):
February 26, 1988 letter from G.E. Trzyna to US NRC (c): March 9, 1988 telephone conversation between NRR and CECO Gentlemen:
A March 9, 1988 telephone conversation was held between NRR representatives and Corm.onwealth Edison personnel to discurs the proposed ATWS installation at Zion Station. This conversation indicate ( that an evaluation as described in Appendix A of reference (a) must be performed on the isolation device that will be installed 1-etween the ATWS logic and the downstream safety-related circuitry. Appendix A is contained in Attachment 1.
Originally, Potter-Brumfield relays were proposed as the isolation device. However, subsequent to the telephone conversation, Commonwealth Edison had contacted other utilities and decided to substitute a Struthers-Dunn relay model No. 219XDX181NE for the Potter-Bcumfield relays.
It is our understanding that the Struthers-Dunn relay has been used as the isolation device in ATWS designs at other utilities. A schematic of our proposed design is outlined in Figure 1.
A review of our proposed installation indicates that it will satisfy criteria items "a" through "d" of Appendix A.
However, items "e" through "g" address specific installation concerns and therefore warrant further discussion, h0b
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Item "e" The isolation device for this modification will be located in a non-harsh area and therefore the requirements of Environmental Qualification (10 CFR 50.49) are not applicable.
In addition, the' relay will be purchased with seismic qualifications and will be installed in accordance with the seismic requirements for Zion Station.
2)
Item "f" Each isolation device will be installed in an individual metal junction box with a metal partition to separate the non safety-related ATWS logic from the safety-related circuitry in order to protect the safety systems from electrical interference.
3)
Item "g" The proposed ATWS installation has been designed to maximize the separation between the components of the reactor protection system and the ATWS system. The ATWS design including the isolation device, will be supplied from an independent power supply, however, not a Class 1E power supply. All the Class lE power supplies are associated with the reactor protection system. Therefore, the same power supply cannot be used for both the reactor protection system and ATWS system.
The implementation dates for installation are contingent upon MRC review and approval of the proposed design. Commonwealth Edison requires substantial lead time in order to ensure appropriate outage planning and scheduling of mulifications.
If the proposed design is approved by August 1988, then the installation will be completed during the Fall 1989, Unit 1 and the Spring 1990, Unit 2 refueling outages.
Please direct any further questions regarding this matter to this office.
Very truly yours,
/I Sg 6
G.E. Trzyna Nuclear Licensing Administrator i
cc: Resident Inspector-Zion J.A. Norris-NRR I
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- N NXA AMSAC ISOLATION DEVICE -
REQUEST FOR ADDITIONAL INFORMATiON Each light water cooled nuclear reactor shall be provided with a system for the mitigation of the effects from anticipated transients without scram (ATWS).
The Comission approved requirements for the ATWS are defined in the Code of Federal Regulations (CFR) Section 10, paragraph 50.62.
The staff has reviewed the Westinghouse Owner's Group generic functional AMSAC designs for compliance with the ATWS Rule.
As a result, the staff has deter-mined that the use of isolators within AMSAC will be reviewed on a plant specific basis. The following additional information is required to continue and com-plete the plant specific isolator review:
Isolation Devices Please provide the following:
a.
For the type of device used to accomplish electrical isolation, describe the spe~cific testing perfomed to demonstrate that the device is acceptable for its application (s).
This description should include elementary diagrams t
when necessary to indicate the test configuration and how the maximum credible faults were applied to the devices, b.
Data to verify that the maximum credible faults applied during the test were the maximum voltage / current to which the device could be exposed, and de-fine how the maximum voltage / current was detemined.
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).
d.
Define the pass / fail acceptance criteria for each type of device.
e.
Provide a comitment that the isolation devices comply with the environ-ment qualifications (10 CFR 50.49) and with the seismic qualifications which were the basis for plant licensing.
f.
Provide a description of the measures taken to protect the safety systems from electrical interference (i.e., Electrostatic Coupling, EMI, Comon Mode and Crosstalk) that may be generated by the ATWS circuits, g.
Provide information to verify that the Class IE isolator is powered from Class 1E source.
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