ML19316A850
| ML19316A850 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 05/05/1980 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Parris H TENNESSEE VALLEY AUTHORITY |
| References | |
| NUDOCS 8005270646 | |
| Download: ML19316A850 (8) | |
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May 05,1980 Docket Nos. 50-327 and 50-328 Mr. H. G. Parris Mdnager of Power Tennessee Valley Authority 500A Chestnut Street, Tower II Chattanooga, Tennessee 37401
Dear Mr. Parris:
SUBJECT:
REQUESTS FOR ADDITIONAL INFORMATION ON SEQUAYAH This letter covers several matters that have been discussed with your staff. is a request for additional information on the low power test program and procedures. A response by May 9,1980 is needed to keep on schedule. is related to the Executive Order Floodplain Management (E.G.
1195S) which we need responses by May 21, 1980. is our position on full load testing of transformers supplying power to vital buses.
Please advise us if your tests have been conducted in accordance with Regulatory Guide 1.68 and the enclosed position.
Please call if there are questions.
Sincerely, A. Schwencer, Chief Licensing Branch No. 2 Division of Licensing Enclo '!res:
As stateo cc w/ enclosures:
See next page j
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Te'nnessee Valley Authority CCs*
Herbert S. Sanger, Jr. Esq.
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General Counsel Tennessee Valley Authority
- L' 400 Co== cree Avenue E11B33 l
Knoxville, Tennessee 37902 Mr. H. N. Culver Tennessee Valley Authority 400 Commerce Avenue, 249A HBB Knoxville, Tennessee 37902 Mr. Michael Harding Westinghouse Electric Corporation P. O. Box 355 Pitt'sburgh, Pennsylvania 15230 Mr. David Lambert Tennessee Valley Authority 400 Chestnut Street Tower II Chattanooga, Tennessee 37401 Mr. J. F. Cox Tennessee Valley Authority 400 Commerce Avenue, W10Cl31C Knoxville, -Tennessee 37902 Resident Inspector / Watts Barr NPS c/o U.S. Nuclear Regulatory Commission-P. O. Box 629 Spring City, Tennessee 37831
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ENCLOSURE 1 REQUEST FOR ADDITIONAL INFORMATION EVALUTION OF SPECIAL TEST PROGRAM 1.
Pre-test predictions have been made to guide the operating crews in the performance of the tests. For example see Table 1 attached to each pro-cedure.
This guidance should be supplemented by providing the,following information to the operating crew and the NRC staff.
a.
The predicted variation of hot leg temperature, core delta T and flow rate versus time. A single transient calculation, initiajing at perhaps 3% power, using FSAR analyses should be sufficient for tests ~1, 2, 5 and 7.
b.
An estimate of the rate of prassure decrease with time for Test 3 in which the pressurizer heaters are turned off.
c.
Bounding analyses for Test 6 to determine the maximum rate of cooldewn and the maximum rate of heatup that may be expected.
d.
The predictions in Table 1 of the procedure for Test 4 (and the other tests) indicate that analyses were performed for operation with various numbers of isolated loops. Provide the assumptions and results of these analyses regarding the variation of RCS and steam generator shell side temperatures versus time in the isolated and non-isolated loops. Also provide your prediction of the direction of primary side flow in the isolation steam generator (s).
e.
In Test 8 you specify a maximum rate of power increase of.75%/ min.
What is the minimum rate of power increase needed for a meaningful test?
For the maximum rare of power increase, provide an analysis which shows the variation of th with time and shows the 65 F loop delta T criteria will not be exceeded.
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2.
Since system pressures may vary appreciably during the tests, the core exit and average temperature limits of Section 2.1.1 are not appropriate,through-out the test. The margin to saturation appears to be the key limiting para-meter.
It appears that errors in temperature and pressure readings under low flow conditions could be such that a subcooling of less than 10 F would not be indicated even if an actual subcooling of 0 F occurs. With respect to core exit thermocouples, the following is noted:
(a) thermocouples are located within sampling chambers in the UHI support columns, (b) with all pumps operating, flow inside the support columns and above the thermocouple is from the upper head region (T close to cold leg T) for outer locations and in upward direction for central region; (c) flow directions and temper-atures for natural circulation conditions have not been tested. Provide a tabulation and discussion of potential inaccuracies and unr.ertainties in the core exit thermccouple and pressure readings that affect the sub-cooling margin.
3.
Although the hot and cold leg pipe Reynolds numbers indicates turbulent flow under natural circulation conditions, flow stratification can exist.
Provide information on the immersion depth, size, number and location of th RTD's foi hot and cold leg temperature measured during the test program.
. Discuss the capability of this instrumentation to give representative values for hot and cold leg temperatures and provide an estimate of the potential inaccuracies and uncertainties in the readings.
4.
Using Tables 2.2-1, " Reactor Trip System Instrumentation Trip Setpoints" and 3.3-4, " Engineered Safety Feature Actuation System Instrumentation Trip Setpoints" of the Technical Specifications, provide, for each ofct-he pro-posed tests, a matrix identifying each functional unit that.will.be bypassed using the permissive interlocks.
For functional units otherwise defeated, identify the trip and describe the method, time, and manpower requirements for restoring its operability.
Verify that the analyses and results presented in the " Evaluation of Special Test Program" did not take credit for any func-tions that were bypassed or defeated using the interlocks or by other means.
5.
Section 2.1.3 refers to a positive moderator temperature coefficient that was considered in the analyses.
Provide the following information: predicted coefficient as a function of temperature; a description of measurements of the moderator temperature coefficient to be made before the special test program starts to verify the prediction, including the temperature range the measurements will cover.
6.
From the discussions during the meeting on 4/23/80 it was understood that the auxiliary spray would be used for pressure control for some tests.
If either of the two valves in the charging lines, which are in parallel with the auxiliary pressurizer spray line, are open there may be no auxiliary spray flow.
If the valves in the charging lines are closed to permit pres-sure control with the auxiliary pressurizer spray, how is pressurizer level controlled, if normal letdown is used?
7.
Explain item (5) in Section 2.1.4 of the Safety Evaluation.
8.
You proposed to block the automatic actuation of safety injection during the performance of the low power test program. Provide a discussion of the safety considerations (both the benefits and possible adverse impacts) of the approach you propose relative to changing setpoints during the test program.
9.
For tests when pressurizer heaters a : turned off or rendered inoperable by loss of power, it is stated in Section 2.1.7 that pressurizer pressure will be controlled by changing pressurizer level.
The recent North Anna incident showed that the pressurizer pressure is very sensitive to level under these conditions. How has this effect been included in the pre-test analysis and test procedures?
10.
You propose to lock out the UHI system during the performance of the low power test program. Provide a discussion of the safety considerations (both the benefits and possible adverse impacts) of the approach you propose.
Clearly list the tests and postulated accidents that may cause the system pressure to decrease sufficiently to result in UHI injection if the system were not locked out.
.- 11. For each instrument that provides an automatic reactor trip, engineered safety feature actuation, or visual indication of a parameter monitored (Section 3.0, Operational Safety Criteria) for manual reactor trip or safety injection, submit an evaluation of the methods used to compensate for this during operation outside the Technical Specification limits. For example, T av is as low as 425 F (Section 2.1.4).
Are the temperatu're readings accurate? Are the measurements of other parameters (e.g., steam generator level) affected?
- 12. Section 4.1.1.1 indicates that at least one RCS pump will be started following every reactor trip. Explain the basis of this action in light of the following considerations:
effects on heat transfer, additional heat source from pump heat, boron mixing, and system pressure cor. trol. Specify that all four pumps should be operating prior to rod withdrawal from a sub-critical position.
- 13. Provide a description of the analyses which indicate that the core will remain covered 'for at least 6000 seconds" following a small LC0A.
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(Section 4.1.2)
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- 14. Low probability alone does not seem sufficient reason to dismiss the single rod withdrawal (Section 4.1.2.3) and rod ejection (Section 4.1.3.6) accidents without analysis. Provide the maximum core heat flux (or fraction of nor-mal heat flux) for this event. Determine whether the conclusion stated in the last sentence of Section 4.2.3.2 is applicable to these events.
- 15. Provide a description of the analyses which indicate that the core will remain covered for 1.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> following a large LOCA.
(Section 4.1.3).
- 16. For the analysis described in Section 4.2.1, provide a figure of core heat flux versus time corresponding to Figure 4.2.1.
- 17. The last sentence of Section 4.2.3.2 states that " Analyses of core'condi-tions" indicate thct the DNB criterion of the FSAR is met. Describe the data or correlations that were used to determine the critical heat flux for low flow conditions that will exist during the test program. Why dcasn't the same conclusion regarding meeting of DNB criteria apply for the RCC bank withdrawal of transients described in Section 4.2.2?
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ENCLOSURE 1 RE00EST FOR ADDITIONAL INFORMATION PROCEDURES FOR LOW POWER TEST PROGR:'1 General :
It is not clear what written instructions the operator will use in the event plant conditions go outside the limits listed in the special test procedures that only the test engineer will use. How will the operator know that he should manually trip' the reactor or manually initiate safety injection?
.g-Specific Comments on Test Procedures Test #7:
Explain why the battery charger is not maintained connected to the DC bus as it would be in a real blackout condition. Any loading effect by the charger should be included in the test.
Justify the use of temporary lights as mentioned in Step 2.14 NOTE.
Unless all areas are blacked out, the test does not validate the assumption that all areas of importance have been identified.
Test #98: In Step 3.4, identify the direction that the pressure will change so that the operator will know the type of " care" he must take.
In Step 5.1.7, 100 ppm increase in boron concentrating should be determined by mass balance rather than by sampling. Sampling may not be valid because of stratification or other lack of uniformity throughout the reactor coolant system.
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EtiCLOSURE 2 HYDROLOGIC EflGIf1EERING QUESTI0t45 RELATIfiG.T0 E.0. 11988 FLOODPLAI1 MAtiAGEMEilT SEQUOYAH fiUCLE/' PLAitT UtlITS 1 AtID 2 DOCKET NUMBERS 50-327/328 Definition (from Executive Order 11988 Floodplain Management)
Floodplain: The lowland and relatively flat areas adjoining inland and coastal waters including floodprone areas of offshore islands, including at a minimum that area subject to a one percent or greater chance of flooding
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in any given year.
1.
Provide descriptions of the floodplains of all water bodies, within or adjacent to the site. On a suitable scale map provide delineations of those areas i
that will be flooded during the one-percent chance flood.
Provide details l
of the methods used to determine the floodplains.
Include 1
your assumptions of and bases for the pertinent parameters used in tne computation of the one-percent flood flow and water elevation.
If studies 4
approved by Flood Insurance Administration (FIA), Housing and Urban Develop-ment (HUD) or the Corps of Engineers are available for the site cr adjoining area, the details of analyses need not be supplied.
You can instead provide the reports from which you obtained the floodplain infcrmation.
2.
Identify, locate on a map, and describe all structures in the ficodplains.
3.
Discuss the hydrologic effects of all. items identified in 2. above. Discuss the potential for-altered flood flows and levels, both u: stream and downstream.
f Include the potential effect of debris accumulating on the plant structures.
Additionally, discuss the effects of debris genera:ed from the site on down-stream facilities.
Provide the details of your analysis.
The level of detail is similar to that identified in item 1. above.
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ENCLOSURE 3 LOCAL TESTING OF TRANSFORMERS It has come to our attention that some applicants did not intend to conduct confirmatory tests of some distribution systems and transformers supplying praer to vital buses as required by Position 3 of Regulatory Guide 1.68, and more specifically by Part 4 of the staff position on degraded grid voltage (applied to all plants in licensing review by the Power Systems Branch since 1976).
Part 4 of the degraded grid voltage position states as follows:
"4 The voltage levels at the safety-related buses should be optimized for the full load and minimum load conditions that are expected throughout the anticipated range of voltage variations of the offsite power source by appropriate adjustment of the voltage tap settings of the intervening transformers. We require that the adequacy of the design in this regard be verified by actual measurement and by correlation of measured values with analysis results.
Provide a description of the method for making this verification; before initial reactor power operation, provide the documentation required to establish that this verification has been accomplished."
Your test descript,f on in FSAR Chapter 14 does not contain sufficient detail for us to determine if you intend to conduct such a test.
It is our position that confirmatory tests of all vital buses must be conducted including all sources of power supplies to the buses. fiodify your test description to indicate that this testing will be conducted in accordance with Regulatory Guide 1,68 and the above cited position.