ML20058G602
| ML20058G602 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 11/29/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20058G596 | List: |
| References | |
| NUDOCS 9312090311 | |
| Download: ML20058G602 (5) | |
Text
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j ff UNITED STATES.
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NUCLEAR REGULATORY COMMISSION j
WASHINGTON. D.C. 200b6-0001 g v'p I
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION I
i RELATED TO AMENDMENT NO. 173 TO FACILITY OPERATING LICENSE NO. DPR j AND AMEN 0 MENT NO. 164 TO FACILITY OPERATING LICENSE NO. DPR-79 TENNESSEE VALLEY AUTHORITY SE000YAH NUCLEAR PLANT. UNITS 1 AND 2 i
i DOCKET NOS. 50-327 AND 50-328
1.0 INTRODUCTION
By application dated September 27, 1993, the Tennessee Valley Authority (TVA or the licensee) proposed amendments to the Technical Specifications (TS) for' i
Sequoyah Nuclear Plant (SQN) Units 1 and 2.
The changes would revise the emergency diesel generator (EDG) surveillance test requirement specified in
.I Section 4.8.1.1.2.a.5 and Section 4.8.1.1.2.d.7, and the combined Basis.
i Section for Specification 3/4.8.1 and 3/4.8.2.
j; Surveillance Requirement 4.8.1.1.2.a.5 presently requires that the EDG be loaded to greater than or equal to 4400 kw for 60 minutes;'whereas, the proposed change would specify that the load is between 3960 kw and 4400 kw.
j Surveillance Requirement 4.8.1.1.2.d.7 (the 24-hour EDG test) presently requires that the EDG be loaded to greater than or equal to 4840 kw during the j
first 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of the test, and to greater than or equal to 4400 kw during the i
remaining 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> of the test.
The proposed amendment would:. (1) change the i
initial time specification of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to a time span of 2 to 2.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />;
)
(2) change the initial load requirement from 4840 kw to a span of 4620 kw to 4840 kw and add a reactive load span of 2380 kvar to 2600 kvar; and (3) change the load requirement for the remainder of the 24-hour test from 4400 kw to a span of 3960 kw to 4400 kw and add a reactive load span of-2140'kvar. to 2370 kvar. Thus, the time and kw load requirements would be changed to spans and reactive load specifications would be added.
A proposed change to the Bases Sections for Specifications 3/4.8.1 and 3/4.8.2 would add the reference for the load-run and the 24-hour endurance tests, which is Regulatory Guide (RG) 1.9, Revision 3, dated July 1993. Also,'the licensee has proposed including a statement that would' allow momentary transients outside the kw and kvar load ranges to occur.without invalidating the test.
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. 2.0 EVALUATION The present TS requirements for short-term EDG loading (4840 kw) and continuous EDG loading (4400 kw) surveillance tests were approved in Unit I and Unit 2 TS amendments issued on January 7,1988. The values were based on guidance given in RG 1.108, Revision 1, " Periodic Testing of Diesel Generator Units Used as Onsite Electric Power Systems at Nuclear Power Plants," the Institute of Electronics Engineers Standard 387-1972, "IEEE Standard Criteria for Diesel-Generator Units Applied as Standby Power Supplies for Nuclear Power Generating Stations," and earlier versions of the Standard Technical Specifications. The limits were designed to ensure that the EDGs are capable of operating at the design maximum short-term and continuous load ratings.
However, at the time that the changes were being incorporated, the test guidance did not provide guidance to ensure that the maximum EDG loads were not exceeded during the tests; i.e., no consideration was given to the maximum EDG load.
During an Operational Readiness Assessment Team inspection conducted in August 1993, the team expressed a concern that the EDGs had been subjected to loads higher than their design rating during surveillance tests.
It was determined that the EDGs had been subjected to loads as high as 5000 kw. A subsequent review of data for tests conducted since February 1993, identified four tests that were performed with loads between 4800 kw and 4900 kw for periods ranging from 47 minutes to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
New guidance related to EDG testing is contained in RG 1.9, Revision 3 and the revised Standard TS (NUREG-1431). Using this guidance, and based on the continuous duty rating of 4400 kw, the licensee has determined that the lower 4
value for testing the EDGs should be 3960 kw (90 percent of the continuous rating). Thus, the load range for the 60-minute test and the long-term test proposed by the licensee is 3960 to 4400 kw. Also, in accordance with the guidance, the range for the short-term rating proposed by the licensee is 4620 kw (105 percent of the continuous rating) and 4840 kw (110 percent of the i
continuous rating).
Based on the new guidance in RG 1.9 and NUREG-1431 that require the 24-hour EDG test be conducted at a power factor range between 0.8 to 0.9, the ranges of excitation reactive (kvar) loads corresponding to the diesel generator output load (kw) ranges specified above have been calculated by the licensee and submitted with this TS amendment for inclusion into the appropriate specifications.
The licensee has chosen to specify a range of reactive loads, rather than the power factor range, because the reactive load (and not the power factor) is a direct readout in the control room.
This will simplify performance of the surveillance tests. The staff has verified that when the EDG load and the exciter load is between the respective kw and kvar values specified in the submittal for the 24-hour test, the EDG will be operating at a power factor between 0.8 and 0.9.
The licensee has determined that the load ranges specified are representative of the actual design basis inductive loading that the EDG would experience under accident conditions. Therefore, the EDG tests will verify operability of the generator excitation circuits as well as operability of the engine.
j
. The proposal to change the length of time that the initial short-term portion of the 24-hour test is conducted from 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to a time span of 2 to 2.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> is designed to clarify the length of time that the EDG is required to operate at the maximum load. The change is designed to incorporate the NUREG-1431 guidance (which states that the test should be conducted for greater than or equal to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />) and the RG 1.9 criteria that recommends only that the test duration be 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. This length of time has been verified by the licensee to be within the EDG rating.
As a result of these calculations, the following limits would be established for the 24-hour test:
EDG LOAD EXCITER LOAD TEST PERIOD 4620 kw - 4840 kw 2380 kvar - 2600 kvar Initial 2 - 2.25 hrs.
3960 kw - 4400 kw 2140 kvar - 2370 kvar Remainder of 24 hrs.
The changes to the Bases sections have'been proposed to indicate that the EDG surveillance tests are in accordance with RG 1.9, Revision 3.
Another proposed change to the Bases would indicate that transients that cause the kw and kvar to momentarily go outside of the specified load ranges would not invalidate the test. Since the new load ranges are small, momentary swings outside of the respective bands are not unexpected. This is consistent with the guidance given in NUREG-1431.
The proposed changes were generated using the guidance provided in RG 1.9, Revision 3 and NUREG-1431.
In addition, they are consistent with the guidance provided in NRC Information Notice 91-13, " Inadequate Testing of Emergency Diesel Generators (EDGs)." The method used to determine that the EDG is operating at the proper power factor during the test by specifying reactive load limits is consistent with the intent of the guidance. The ranges of EDG load and excitation load provide assurance that the EDGs will be tested within the capabilities of the generator and exciter, and within the constraints of the manufacturer's capability curves to ensure that the ratings are not exceeded. Based on this information, the staff has determined that the proposed changes are satisfactory.
3.0 STATE CONSULTATION
4 In accordance with the Commission's regulations, the Tennessee State official was notified of the proposed issuance of the amendments.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the i
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. amendments involve no significant hazards consideration, and there has been no public comment on such finding (58 FR 57858). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the l
public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Consnission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
l Principal Contributor:
D. LaBarge Dated: November 29, 1993 i
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e AMENDMENT NO. 173 FOR SEQUOYAH UNIT NO. 1 - DOCKET NO. 50-327 and AMENDMENT NO. 164 FOR SEQUOYAH UNIT NO. 2 - DOCKET NO. 50-328 DATED:
tiovember 29, 1993 DISTRIBUTION:
Docket Files-
~ NRC & Local PDRs SQN Reading File S. Varga i
F. Hebdon B. Clayton D. LaBarge l
E. Merschoff RII P. Kellogg RII R. Crlenjak RII OGC 15-B-18 D. Hagan MNBB-3206 l
G. Hill PI-37 (2 per docket)
C. Grimes 11-E-22 ACRS(10)
OPA 2-G-5 OC/LFDCB MNBB-9112 1
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