ML20058F567
| ML20058F567 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 07/13/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20058F565 | List: |
| References | |
| NUDOCS 8207300566 | |
| Download: ML20058F567 (2) | |
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NUCLEAR REGULATORY COMMISSION
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 72 TO -
FACILITY OPERATING LICENSE NO. DPR-53 CALVERT CLIFFS NUCLEAR POWER PLANT UNIT NO. 1 DOCKET NO. 50-317 Introduction By application for license amendment dated June 30, 1982, Baltimore Gas and Electric Company (BG&E) requested changes to the Technical Specifi-cations (TS) for Calvert Cliffs Unit 1.
The proposed changes would decrease the maximum allowable response and closure times for the Main Steam Isolation Valves (MSIVs).
In addition, this license amendment corrects a typographical error which occurred in issuance of License Amendment 71~for Calvert Cliffs Unit 1.
Discussion i
On June 24, 1982, the NRC issued License Amendment 71 for Calvert Cliffs Unit I which authorized Cycle 6 operation at 2700 MWt. As part of Amendment 71, TS 4.7.1.5, " Main Steam Isolation Valves" was changed to permit an increase in the maximum allowable MSIV closure time fr'om 3.6 to 4.0 seconds.
In addition, a change was made in TS Table 3.3-5,
" Engineering Safety Features Response Times" to increase the MSIV response
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time
- from 6.9 to 12.9 seconds.
A subsequent evaluation by BG&E indicated that implementation of the revised MSIV closure and response times might lead to decreased plant 1
availability resulting from an increased frequency of reactor trips due to low st am generator level. Accordingly, by application dated June 30, 1982, BG&E requested that the previous values of MSIV closure and response times, 3.6 and 6.9 seconds, respectively, be reinstatea
. in the TS.
Evaluation Of the two design basis events which result in automatic MSIV. closure, the main steam line break is the most limiting in that it produces the lowest minimum DNBR.
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An MSIV response time of 6.9 seconds is more conservative than 12.9 seconds because the mass / energy blowdown from the unaffected steam generator is 1
greater in the 12.9 second case. This increases the rate and extent of l
reactor coolant system cooldown and results in a more limiting, transient, minimum DNBR.
l In addition, for the same preaccident steam generator water / steam mass, i
an MSIV response time of 6.9 seconds would produce a lower maximum con-tainment pressure than an MSIV response time:of 12.9 seconds. Accordingly, the consequences of the main steam line break are less severe for an MSIV response time of 6.9 seconds (with a corresponding MSIV closure time of 1
3.6 seconds) than for an MSIV response time of 12.9 seconds (with a j
corresponding MSIV closure item of 4.0 seconds). No new accidents have been introduced, or any safety margins reduced, as a result of the decrease in maximum allowable MSIV closure and response times, j
An additional change to the TS is being made to correct a typographical error which occurred in our issuance of License Amendment 71 for Calvert i
Cliffs Unit 1.
TS Table 3.2-1, "DNB Parameters", footnote (***), contains i
the phrase, "...when BASSS is inoperable..." This phrase should actually i
have been, "...when BASS is operable..." This change is consistent with 1
BG&E's application for License Amenament 71, dated February 17, 1982..
.i Furthermore, the change has no safety significance and is administrative in nature.
i Environmental Consideration i
We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact.
Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 551.5(d)(4), that an environmental impact statement or negative declaration and environ ~
mental impact appraisal need not be prepared in connection with the issuance of this amendment.
2 Conclusion We have concluded, based on the considerations discussed above, that:
(1) *because the amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated, i
does not create the possibility of an accident of a type different from any evaluated previously, and does not involve a significant reduction in a margin of safety, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health
,I and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
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