ML20083K736
| ML20083K736 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 01/26/1979 |
| From: | Gilleland J TENNESSEE VALLEY AUTHORITY |
| To: | Varga S Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7901300124 | |
| Download: ML20083K736 (3) | |
Text
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TENNESSEE VALLEY AUTHORITY OH ATTANCCG A. TENNCssEE 37401 500C Chestnut Street Tower II JAN 2 01979 Director of Nuclear Reactor Regulation Attention:
Mr. S. A. Varga, Chief Light Water Reactors Branch No. 4 Division of Project Management U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Varga:
In the Matter of the Application of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 Enclosed is TVA's revised response to Quality Assurance Branch question 2 on our application for the Sequoyah Nuclear Plant trans-mitted by your letter dated September 20, 1978, to N. B. Hughes. This revised response will be incorporated into the Sequoyah Nuclear Plant Final Safety Analysis Report by Amendment 60.
Very truly yours, l)s MS?4'-
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E. G111 eland Assistant Manager of Power Enclosure 4
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EECLOSURE RESPONSE TO QAB QUESTION 2 0F SEPTEMBER 20, 1978, LETTER 14.5 With regard to the initial test program,'our review of the test descrip-tions modified in amendment 48 disclosed that the description of SU-9.4, Plant Trip From 100% Power, is not sufficiently descriptive to conclude that satisfactory acceptance criteria have been established.
Modify the test abstrset to:
(1) identify the variables or parameters to be monitored for each trip; (2) pr, ovide assurance that test results will be compared with predicted results for the actual trips to be performed (vice accident analysis predictions); and (3) provide quantitative acceptance criteria and their bases for the required degree of con-vergence of actual test results with predicted results for the monitored variables and parameters for each trip.
Response
The FSAR test abstract for SU-9.4 is considered to be saticfactory as revised in Amendment 48, September 15, 1977.
Regulatory Guide 1.68 states that plant dynamic response should be verified to be in accord-ance with design for the two transients addressed by SU-9.4.
This objective is satisfied by Test Objectives 1 and 2 and Acceptance Criteria 1-5 of SU-9.4A and by Test Obj ective 1 and Acceptance Criteria 1-3 of SU-9.4B.
The primary intent of this test is to (1) observe plant dynamic response with automatic control systems configured for normal power operation, and (2) verify that sensor response times assumed in the accident analyses are conservative. The basic design function of automatic control systems is that they should prevent protective or safeguards features actuation for their associated design transient.
The verification of this basic design function of automatic control systems is reflected in the Acceptance Criteria for this test in that'the control systems should prevent pressurizer and steam generator safety valve lift, safety injection, and turbine overspeed. Adequate monitoring is provided during the test to measure the hot leg RTD and nuclear flux response referenced in Acceptance Criteria 2 and 3 of SU-9.4A and turbine speed referenced in Acceptance Criteria 1 of SU-9.4B.
Objective (3) of SU-9.4A and Objective (2) of SU-9.4B whic'h refer to test data evaluation for possible i=provement of automatic control system response are. considered to be secondary to the primary objectives and Acceptance Criteria discussed above.
The monitoring of several additional parameters during the transients is a logical use of the opportunity provided by these transients to add detailed knowledge of centrol systems performance.
Quantitative evaluation criteria are established in the startup test instruc-tions to be used as guides.to evaluating individual parameter responses monitored during the transients.
Due to the preliminary nature of control system settings (gain, time, constants, etc.) as well as the variable nature of core decay heat with burnup, failure to satisfy an evaluation criteria does not necessarily Q14.5-1
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l indicate improper control system response as would be indicated by a failure to meet a primary Acceptance Criteria discussed in the preceding paragraph.
Since this secondary test otjective is concerned only with control system optimization and not with the basic design function of control systems and has no impact on plant safety, it is not appropriate to include the particular variables monitored or evaluation criteria associated with this test objective in the FSAR.
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