ML20059E357

Safety Evaluation Supporting Amend 126 to License DPR-79

ML20059E357
Person / Time
Site:	Sequoyah
Issue date:	08/27/1990
From:	Office of Nuclear Reactor Regulation
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ML20059E343	List: ML20059E357
References
NUDOCS 9009100151
Download: ML20059E357 (4)

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+*gCao g-UNITED STATES f

NUCLEAR REGULATORY COMMISSION 5

WASHINGTON, D. C 20666 e.,,4 h

ENCLOSURE l

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION

SUPPORTING AMENDMENT NO.126 TO FACILITY OPERATING LICENSE NO. OPR-79 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT, UNIT 2

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DOCKET NO. 50-328 i

1.0 INTRODUCTION

By letter dated May 21, 1990, the ' Tennessee Valley Authority (the licensee).

requested a change to Section 3/4.6.1, Primary Containment, of the Sequoyah NuclearPlant, Unit 2,TechnicalSpecifications(TSs)oncontainmentAppendixJ Type A or integrated leak rate tests (CILRTs). The proposed change is'to add L

a footnote to Surveillance Requirement (SR) 4.6.1.2.b regarding accelerated L

CILRT test schedules. The two tests perfomed on Unit 2 during the Unit 2-L Cycle 2' refueling. outage (November 1984) and the Unit 2 Cycle 3 refueling outage (March 1989) were classified as failed tests. In accordance with SR 4.6.1.2.b, these two consecutive failures require an accelerated test frequency..

.The licensee's proposed TS change requests an exemption from the accelerated test frequency in SR 4.6.1.2.b for.the Unit 2 Cycle 2 and Cycle 3 test. failures.

Without this change, the accelerated test frequency would require a Unit 2 CILRT in-the upcoming Cycle 4 refueling outage which is scheduled to begin in October 1990.

2.0' DISCUS $10N I

In its application, the licensee also requested an exemption for Unit 2 from the requirements of 10 CFR Part 50, Appendix J. Section 'III.A.6.(b) on consecutive CILRT (i.e;, Ty)e A test) failures. The last two Type-A tests performed on L

1 Unit 2 during tie Cycle 2 (November 1984) and Cycle 3 (March 1989) refueling l

outages'were classified as failures. Due to these two consecutive failures, Unit 2 is required to perform Type A tests at an accelerated frequency of at least every 18 months until two consecutive T The l-licensee's bases for. the exemption are that (ype A tests meet 0.75 La.1) increasing th Type A tests and conducting a-test in the Unit 2 Cycle 4 refueling outage would.

not increase the level of confidence for containment integrity, and (2) the hardships and impact of performing a test during the Cycle 4 refueling outage.

.q The exemption will be'a separate evaluation issued by the staff.

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3.0 EVALUATION

' Appendix J,Section III.A.6.(b) requires that if two consecutive periodic CILRT tests fail to meet the ap)licable acceptance criteria (i.e., 0.75 La), a test i

shall be performed at eac1 plant shutdown for refueling'or approximately every 18 months, whichever occurs first, until two consecutive tests meet the accept-ance criteria, after.which time the retest schedule of these tests will be three approximately equal intervals during each 10. year service period. The staff has reviewed the history of CILRT tests conducted at the plant and found-that the last two CILRT as.found results have been failures as noted below:

CILRTs As.found' O.75 La 1.0 La Status performed leak rate limit limit

-(%perday)

(%perday)

(%perday)

Preoperational test-(1981) 0.14 0.1875 0.25 pass Test 1 (1984) 0.22 0.1875 0.25 failure Test 2 (1989) 0.20 0.1875 0.25 failure-l The staff noted that the last two CILRT results exceeded the acceptable limit.

of 0.75 La required by Appendix J but did not exceed the maximum allowable rate of 1.0 La. This is the leakage rate assumed for the containment during a loss.of.

e coolant accident. The licensee stated that the root cause of the Cycle 2 CILRT failure was packing leakage from two outboard root valves on two containment pressure sensing lines. The licensee performed maintenance on'the pressure sensing lines during the Cycle 2 refceling outage and repaired the root valves which resulted in an immediate reduction in the measured leak rate to below the TS -limit and the applicable. Appendix J acceptance criteria. -The licensee also implemented corrective actions to prevent the pressure sensing line leakage.

l-These. actions include:-

l (1) Programmatic review of the instrument maintenance and operation activities to identify _ potential impacts on containment integrity, and i

'(2) Expansion of the local leak rate test (LLRT) program to require an LLRT p

following any maintenance performed on the pressure sensing lines.

L Post-maintenance leak rate testing is required and added to the Surveil =

L lance Instruction (SI) 159.1, " Leak Rate Test on Containment Pressure L

-Instrumentation."

The licensee. stated that the primary cause of the Cycle 3 CILRT failure was due to excessive leakage through Penetration X-59. The root cause was stated to be personnel error in connecting the hose from the test equipment to the test connection for the valves associated with Penetration X-59. Another

. factor that contributed to the excessive leakage through Penetration X ~

involved a maintenance sequence that occurred when the outboard containment isolation valve (FCV-67-88) was previously disassembled, cleaned, and reassembled during the outage. The licensee has implemented _ corrective actions for the root causes of excessive leakage from Penetration X-59.

These actions include:

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'(1) ~ Revision of the LLRT program (SI-158.1) to include instructional steps thatL require the test hoses to be visually inspected to ensure that no restrictions or crimped conditions exist, and p

(2) Revision of the Maintenance Instructions (0-M1-MVV-000-008.0) to ensure that when soft-seated butterfly valves without. internal disc stops are removed from the piping, the valve operator limits are set with the valve body attached to ensure that valve position is established prior to reinsta11ation.

t The staff has reviewed the licensee's submittal and agrees with the licensee H

that the root cause of each of the last two CILRT failures was due to excessive leakage of a single component or penetration in the containment boundary and not a general containment integrity problem. Even with the leakage, the CILRT 1

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results were found within the maximum allowable leak rate of 1.0 La.

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licensee has corrected and repaired'the components that caused the CILRT L

f ailure and implemente? corrective actions to prevent future component frilure.

Additionally, the current Appendix J allowable leak rate limit on Type A tests contains a 25% safety margin between the leak rate acceptance criteria and the leak rate assumed for the containment during a loss-of-coolant accident.

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L proposed revision to Appendix J currently under consideration would remove p'

the margih. With the above corrective actions and the fact that the last two-1 b

CILRT failures were below the maximum allowable leak rate of 1.0 La, and the l

staff issued an exemption to Section III.A.6.(b) of Appendix J of 10 CFR Part i

50 in its letter dated August 27, 1990, the staff concludes that the failures have no significant impact on containment integrity and no benefit would be gained by requiring the licensee' to perform an accelerated Type A test, j

'Therefore, the staff concludes that the proposed TS changes are acceptable.

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1 4.0 ENVIRONMENTAL CONSIDERATIO_N c

.This amendment involves a change'to a requirement with respect to the installa-tion or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements. The i

y staff has determined that the amendment involves 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 i

cumulative occupational radiation exposure. The Comission has previously issued a proposed finding-that this amendment involves no significant hazards consideration and there has been no public comment on-such finding. Accordingly, the amendment meets the eli forth in 10 CFR 51.22(c)(9)gibility criteria for categorical exclusion set Pursuant to 10 CFR 51.22(b), no environmental impact statement nor environmental assessment need be prepared in connection L

with the issuance of this amendment.

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5.0 CONCLUSION

The Comission made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Register (55 FR 26296) on June 27,1990 and consulted with the State of Tennessee. No public comments were received and the State of Tennessee did not have any comments.

The staff has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the will not be endangered by operation in the proposed manner, and (2) public such-activities will be conducted in compliance with the Comission's. regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security nor to the health and safety of the public.

Principal Contributor:

J. S. Guo Dated: August 27, 1990

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