ML19329C726
| ML19329C726 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/23/1975 |
| From: | Stello V Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19329C724 | List: |
| References | |
| NUDOCS 8002190845 | |
| Download: ML19329C726 (2) | |
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ENCLOSURE d
d UPDATE TO DAVIS BESSE UNIT 1 SAFETY EVALUATION REPORT l
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4 The following changes shall be made to the Davis Besse Unit 1 EICSB l
Safety Evaluation Report dated June 23, 1975.
Section 7.2 Page 2 U
Replace Paragraph 5, 6 and 7 with the following:
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The applicant has identified two changes from the referenced design.
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These involved the power supply interrupt interface between the RPS and i
i the control rod drive mechanisms. These changes are:
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1.
Two manual reactor trip switches in series (instead of one) which l
interrupt power to each undervoltage coil of the main ac feeder breakers and thereby disconnect power to the rod drive mechanisms.
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A redundant diverse method of power interrupt utilizing silicon control rectifiers (SRC) in the rod group power supplies instead of de breaker interrupt of the holding power supplies.
l During the course of the review it was determined that the diverse j
method of power interrupt was not seismidally qualified, and therefore t
unacceptable.
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The applicant committed to modify his design by providing two additional l
qualified Class IE ac main feeder breakers ( in series with the existing j
ac breakers ) and retain the diverse SCR trip scheme as a non-safety l
back-up. These changes conform to the requirements of IEEE Std 279-1968 I
(which is the applicable design criteria for the Davis Besse RPS system) and are therefore acceptable conditioned only on the satisfactory doc-umentation of this change in the FSAR-1 The applicant referenced BAW-10003 Topical Report for the RPS equipment l
qualification testing.
This document has recently been reviewed generically t
and found conditionally acceptable subject only to the satisfactory f
resolution of various interface concerns.
The applicant was requested to address these concerns and document their responses in the FSAR.
We will report the results of our review of this outstanding item in the supplementary safety evaluation report.
Subject to the satisfactory resolution of this item, we have concluded that the RPS design is acceptable.
t Section 7.3.1 General Page 3 Delete the reference to Section 7.3.1 in the last sentence of the second i
i paragraph.
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n Section 7.3.1 ESF Actuation / Basic Logic Page 3 1.
Replace sentence 5 and 6 of the first paragraph with the following:
The applicant has documented in the FSAR a comparison of his design to that of Millstone Unit 2.
The staff's review and
. conclusions pertaining to the logic design and the automatic test features described in Millstone 2 SER, dated May 10, 1974, are applicable for this case and have been found acceptable.
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Replace Paragraph 2 with the following:
We have concluded that the system meets the requirements of IEEE Std 279-1971 and is therefore acceptable.
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