ML19274C925
| ML19274C925 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 12/21/1978 |
| From: | Ippolito T Office of Nuclear Reactor Regulation |
| To: | Jackie Jones CAROLINA POWER & LIGHT CO. |
| References | |
| NUDOCS 7901050393 | |
| Download: ML19274C925 (5) | |
Text
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NUCLEAR REGULATORY COMMISSION j
WASHINGTON, D. C. 20555
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December 21, 1978 Docket tios. 50-325 and 50-324 Mr. J. A. Jones Executive Vice President Carolina Power & Light Company 336 Fayetteville Street Raleigh, florth Carolina 27602
Dear Mr. Jones:
As discussed in o'ur phone conversation with your staff on December 8,1978, we are considering the role of physics startup tests in the licensing of reload cores for BWRs. We have refined the list of tests that constitute what we believe is a minimum startup test program for a reloaced core.
It is planned that these tests will become part of the Regulatory Guide on Reactor Reloads.
The safety analysis for a reloaded core is based upon a specifically designed core configuration.
In our review we assume that the reloaded core configuration will conform to the designed configuration. A physics startup test program provides some assurance that the core conforms to the design. We believe that the minimum list of tests should be:
1.
A visual inspection of the core including a photographic or videotape record.
2.
A check of core power symmetry by checking for mismatches between symmetric detectors.
3.
Withdrawal and insertion of each control rod to check for criticality, and mobility.
4.
Comparison of predicted and measured critical insequence rod pattern for nonvoided conditions.
Before we could judge the adequacy of a physics startup test program we would need additional information. The added information would be:
(a) A description of the test sufficient for us to evaluate the adequacy of the test.
(b) The acceptance criteria and the bases that provide assurance that the core conforms to design.
790105039 3
r Mr. J. A. Jones December 21, 1978 (c) The specific actions to be taken if the acceptance criteria are not met.
You may wish to review your present startup test program to ensure conformance with the above list of tests (1-4).
Your reload submittals should include information detailed in items (a)-(c).
For your con-venience the attachment to this letter provides a set of questions used in connection with previous reload reviews regarding specific physics startup tests.
We hope this information will be helpful in preparing your reload ~
submittals for Brunswick Units 1 and 2.
Sincerely,
.i
.&54l/pna $h Thomas A/fIppolito, Chief Operating Reactors Branch #3 Division of Operating Reactors
Enclosure:
Physics Startup Test Rr. load Questions ces w/ enclosure:
See next page
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.. Describe how the calculated critical rod pattern is to be determined including identification of the computer code to be used and the method for adjusting or biasing the calculated rod worths. Also, indicate how adjustments for temperature differences between the predicted and actual core conditions are to be taken into account.
Indicate the criteria for determining when a detected reactivity anomaly has safety significance and the action to be taken when such an anomaly is discovered.
ATTACHMENT PHYSICS STARTUP TEST RELOAD QUESTIONS 1.
Provide a description of tne core locu!ng verification procedures to be followed during the refueling of the core for the upcoming cycle, including the number of 17 dependent checks to be made of the actual core loading, the intended core loading and the consistency between the two.
2.
The application of the 1.06 safety limit MCPR to your plant is based among other things on the assumption that the total TIP uncertainty during the upcoming cycle will not be significantly higher than 8.7%.
The 8.7% total TIP uncertainty currently accepted as typical for BWR reload cores includes a contribution from geometric and random noise uncertainties amounting to 6.5%.
A total TIP uncertainty larger than 8.7% or more specifically a combined geometric-random noise uncertainty greater than 6.5% would indicate that the 1.06 safety limit MCPR is not appropriate and that a higher limit should be applied.
In view of this, provide the details of the methods to be used in deter-mining the geometric and rando, noise TIP uncertainties during the upcoming cycle. The descriptivn should be adequate to show that the measurement and data analysis techniques are consistent with the methods originally used by GE to arrive at the currently accepted uncertainties, i.e., those on which the 1.06 limit is based.
Include the acceptance criteria for TIP geometric-random noise uncertainty.
We suggest that if this uncertainty exceeds 6.5% to such an extent that the total TIP uncertainty increases from 8.7% to 10.7% and/or any difference between pairs of symmetric TIP's is observed to be greater than 23% of their average signals, an analysis should be performed. This analysis should demonstrate that the plant is operating in compliance with the safety limit CPR for all anticipated transients and that no bundles will be operating in boiling transition or in excest of the 1%
cladding strain limit during steady state operation.
Acceptable means of showing compliance could be the identification of offsetting plant specific conservatisms or an increase in the safety limit.
If com-pliance cannot be demonstrated by analysis, an appropriate report should be made to the NRC pursuant to Regulatory Guide 1.16 and steps taken to formally change the safety limit.
3.
The comparison of measured and calculated critical rod pattern is intended to detect any significant reactivity anomaly.
It would be expected that such a test would sample an adequate portion of the care to assure that localized reactivity anomalies do not exist, and for that reason should be a multiple-rod test rather than a few rod criticaility such as a face-adjacent test. Also, the core should be free of voids at the time of the test.
r Carolina Power & Light Company December 21, 1978 cc: Richard E. Jones, Esquire Carolina Power & Light Company 336 Fayetteville Street Raleigh, North Carolina 27602 George F. Trowbridge, Esquire Shaw, Pittman, Potts & Trowbridge 1800 M Street, NW Washington, D. C.
20036 John J. Burney, Jr., Esqeire Burney, Burney, Sperry & Barefoot 110 North Fifth Avenue Wilmington, North Carolina 28401 Southport - Brunswick County Library 109 W. Moore Street Southport, North Carolina 28461
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