ML20028G854

Exemption Allowing Unit 2 to Continue on Normal Type a Test Frequency Having Util Conduct Third Type a Test of First 10- Yr Svc Period in Unit 2,Cycle 5 Refueling Outage in 1992

ML20028G854
Person / Time
Site:	Sequoyah
Issue date:	08/27/1990
From:	Varga S Office of Nuclear Reactor Regulation
To:	TENNESSEE VALLEY AUTHORITY
Shared Package
ML20028G855	List: ML20028G854
References
NUDOCS 9009050167
Download: ML20028G854 (7)

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4-3 7590-01

_ UNITED STATES OF AMERICA E

NUCLEAR REGULATORY COMMISSION r

In the Matter of

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TEtifiESSEE VALLEY AUTHORITY

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Docket No. 50-328 (Sequoyah Nuclear Plant, Unit 2)

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EXEMPTION p-i I.

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= The Tennessee Valley Authority (TVA) holds facility Operating License No.

DPR-79 which authorizes operation of the Sequoyah Nuclear Plant, Unit ? (the facility, Unit?). The license provides, among other things, that the

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facility is subject to all rules, regulations, and orders of the Nuclear l

Regulatory Cour,ission (the Comission) now or hereafter in effect.

l The facility consists of a pressurized water reactor located on TVA's Sequoyah site in Hamilton County, Tennessee.

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II.

Section Ill.A.6(b) of Appendix J to 10 CFR Part 50 requires that if two consecutive Type A tests fail to meet the applicable acceptance criteria, a Type A test shall be conducted at each refueling cutage. This increased testing frequency would continue until two consecutive Type A tests shall meet' the acceptance criteria, after which time the normal retest frequency of three Type A tests at approximately equal intervals within each 10-year service period would resume. The approximately equal intervals are defined in Surveillance Requirement 4.6.1.2.a of the Sequoyah Technical Specifications (TSs) as 401 10 ' months. Type A tests means tests of the primary reactor containment to measure the expected overall integrated leakage rate of the containment for the loss-of-coolant accident conditions.

The exenption would allow (1) Unit 2 to continue on the normal Type A test frequer.cy having TVA conduct the third Type A test of the first 10-year service period in the Unit 2 Cycle 5 refueling outage in 1992 and (2) TVA not to conduct a Type A test in the upcoming Unit 2 Cycle 4 refueling outage which is scheduled to begin in September 1990. Type A tests conducted in the Unit 2 Cycle 2 (November 1984) and Unit 2 Cycle 3 (March 1989) refueling outages are both' considered failures because they did not meet the leak rate acceptance criteria.

In its application dated May 21, 1990 for relief, TVA stated that it was requesting an exemption from Appendix J because it considered the increased

-frequency of the type A tests inappropriate for the causes of the two consecutive Type A test failures. TVA stated that the measured leakage results i

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for the two tests were below the maximum allowed leakage for the Unit 2 con.

tainmunt and a general containment leakage problem does not exist. A correc.

tive action program that addresses-the causes of the test tuilures has been inipleniented at Sequoyah. TVA_ concluded that increasing the frequency of the L

Type A tests at Unit 2 would not provide a corresponding increase in _the level of confidence of demonstrating Unit 2 containment integrity. TVA further stated that the economic impact of performing the test in engineeri.,9 time and the additional unit shutdown time to conduct the test would be an imprudent use of its resources.

The' staff has reviewed the history of Type A tests conducted at the plant and found that the last two Type A as-found test results have been 1

j failures as' noted below:

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Type A Tests As.found 0.75 La 1.0 La Status i

performed leak rate limit limit

(%perday)

(% per day)

(% per day)

Prcoperational 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 The staff noted that the last two test results exceeded the acceptance limit of 0.75 La required by Appendix J but did not exceed the maximum allowable rate of 1.0 La for Sequoyah. TVA stated that the root cause of the Cycle 2 failure

. was packing leakage from two outboard root valves on two containment pressure sensing lines. TVA stated-that it performed maintenance on the pressure sensing lines during the Unit 2 Cycle 2 refueling outage and repaired the root valves

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O which resulted in an immediate reduction in the measured leak rate to below the acceptance limit. TVA further stated that it had also implemented corrective actions to prevent the pressure sensing line leakage in the future. These actions include the following:

(1) Programmatic review of the instrument maintenance and operation activities to identify potential impacts on containment integrity, and (2) Expansion of the local leak rate test (LLRT) program to require an LLRT following any maintenance performed on the pressure sensing lines.

Post-t maintenance leak rate testing is required and added to the surveillance Instruction (SI) 159.1, " Leak Rate Test on Containment Pressure Instrumen-tation".

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TVA stated that the primary cause.of the Cycle 3 test failure was due to excessive 1(akage through Penetration X-59. ' The root cause was a personnel I

l error in connecting the hose from the test equipment to the test connection for the valves associated with Penetration X-59. TVA further stated that another j

i factor that contributed to the. excessive leakage through Penetration X-59 involved a maintenance sequence that occurred when the outboard containment L

iscletion valve (FCV-67-88) was previously disassembled, cleaned, and reassembled during the outage. TVA stated that it has implemented corrective actions for the root causes of excessive leakage from Penetration X-59.

These actions include the following:

(1) Revision of the LLRT program (SI-158.1) to include instructional steps that

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require the test hoses tc be visually inspected to ensure that no restrictions or crimped conditions exist, and l

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5 (2) P.evision of the Maintenance Instructions (0-MI-MVV-000-008.0) to ensure that when soft-seated butterfly valves without internal disc stops are.

rcmoved from the p aping, the _ valve operator limits are set with the valve body attached to ensure that valve position is established prior to reinsta11ation.

The staff has reviewed TVA's submittal and agrees with TVA that the-root cause of each of the-last two Type A test failures was due to excessive leakage of a single component or penetration in the containment boundary and that a-general cor.tainment leakage problem does not exist. Even with the excessive leakage, the test results were below the maximurn allowable leak rate of'1.0 La for.Sequoyah Unit P.

TVA has corrected and repaired the components that caused the two Type A test failures and implemented a corrective action program that addresses the causes of these test failures to prevent future test failures.

/dditich611), the current Appendix J 1eak rate limit for Type A tests contains a 25% safety rargin between the leak rate test acceptance criteria and the leak rateassuredforaloss-of-coolantaccident(i.e.,La). A proposed revision to Appendix J currcntly under consideration would remove this margin in the h

- futurG llith the above corrective actions and the fact that the last two test failures were below the maxirnum allowable leak rate of 1.0 La, the staff has L

concluded that the requested exemption has no significant impact on containment 1:

L integrity and no benefit would be gained by requiring TVA to perform Type A

t tests on an accelerated test frequency. Therefore, the staff concludes that the.lihnsee's requested exernption from the accelerated Type A test frequency

-for the Type A test failures should be granted. This exemption applies only to

g the Type A test failures in the' Unit 2 Cycle 2 and Unit 2 Cycle 3 refueling Lo outages as two consecutive '.est failures. Thus, if a Type A test failure were to occur during the Unit 2 Cycle 5 refueling outage, the next scheduled test for Unit 2, that failure w)uld constitute a second consecutive failure follow-ing the test failure in t'ie Unit 2 Cycle 3 outage and TVA would be required to take action accordingly. There is no condition on the operation of Unit 2.

III.

Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12, this exemption is authorized by law, will not present an undue risk to-the public health and safety, and is consistent with the common defense and security. The Commission further determines that special circumstances, as provided in 10 CFR 50.12(a)(2)(ii),' are present justifying the exemption; namely, that the application of the regulation in the particular circumstances for Unit 2 in the-Unit 2 Cycle 4 refueling outage would not serve, and is not necessary, to achieve the underlying purpose of the rule. The application of the ' regulation is not necessary to assure the integrity of the containment in the event of a postulated design basis loss-of-coolant accident.

Accordingly, the Commission hereby grants an exemption from Section 111.A.6(b) of Apper. dix J to 10 CFR Part 50 for Sequoyah Unit 2.

Pursuant to 10 CFR 51.32, the Commission has determined that the granting of this Exemption will have no significant impact on the environment. An

" Environmental Assessment and Finding of No Significant Impact" related to this Exemption was published in the Federal Register (55 FR 34972) on August 27, 1990.

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For further details with respect to this action, see the request for exemption dated May 21,-1990, which is available for public-inspection at the_

Ccmission's Public Document Room, Gelman Building, 2120 L Street, N.P.,

Washington, D.C., and at the Chattanooga-Hamilton County Library,1001 Broad Street, Chattanooga, Tennessee'37402.

This Exemption-is effective upon issuance.

FOR THE NUCLE R

ATORY COMMISSION d

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ven A.

rja, Wre t r Division of Reactor Pr ts - 1/II Office of Nuclear Reactor Regulation Dated at Rockville, Maryland, this 27th day of August, 1990.

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