ML20246C870

Proposed Tech Specs Re Surveillance Requirements for Type a Containment Leakage Rate Tests

ML20246C870
Person / Time
Site:	Sequoyah
Issue date:	05/01/1989
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20246C867	List: ML20246C862 ML20246C870
References
NUDOCS 8905100052
Download: ML20246C870 (12)

Text

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ENCLOSURE 1 PROPOSED TECH ICAL SPECIFICATION CHANGE SEQUOYAH NUCLEAR PLANT UNIT 1 DOCKET NO. 50-327 (TVA-SQN-TS-89-11)

LIST OF AFFECTED PAGES Unit 1 3/4 6-3 b

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CONTAINMENT SYSTEMS SURVEILLANCE REQUIREMENTS l I L

4.6.1.2 I The containment leakage rates shall be demonstrated at the following test schedule and shall be determined in conformance with the criteria speci-fied in Appendix J of 10 CFR 50 using the methods and provisions of ANSI N45.4-1972; however, the methods of ANSI /ANS 56.8-1987 for mass point data analysis may be used in lieu of the methods' sp~ecified in ANSI N45.4-1972. R106 1 l

a. l Three Type A tests (Overall Integrated Containment Leakage Rate) shall be conducted at 40 + 10 month intervals # during shutdown at P (12psig)duringeach10-Fearserviceperiod. The third test of each set shall be conducted during the shutdown for the 10 year plant inservice i 5pection.  ;

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If any periodic Type A test fails to meet 0.75 La, the test schedule for subsequent Type A tests shall be reviewed and approved by the  !

Commission.

If two consecutive Type A tests fail to meet 0.75 L '

a a Type A test shall be performed at least every 18 months until two consecutive Type A tests meet 0.75 aL at which time the above test schedule may be resumed, c.

The accuracy of each Type A test shall be verified by a supplemental test which:

1.

Confirms the accuracy of the Type A test by verifying that the difference between supplemental and Type A test data is within 0.25 La*

2.

Has a duration sufficient to establish accurately the change in leakage rate between the Type A test and the supplemental test.

3.

Requires the quantity of gas injected into the containment or bled from the containment during the supplemental test to be l

equivalent to at least 25 percent of the total measured leakage at Pa (12 psig). .

d.

Type B and C tests shall be conducted with gas at Pa (12 psig) at intervals no greater than 24 months except for tests involving:

1. Air locks, 2.

Penetrations using continuous leakage monitoring systems, and 3.

Valves pressurized with fluid from a seal system.

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• fnbr fo onof SEQUOYAH - UNIT 1 3/4 6-3 Amendment Nc.102 Starch 2, 1989

i ENCLOSURE 2 PROPOSED TECHNICAL SPECIFICATION CHANGE SEQUOYAH NUCLEAR PLANT UNIT 1 ,

1 DOCKET NO. 50-327 -

(TVA-SQN-TS-89-11)

DESCRIPTION AND JUSTIFICATION FOR q PROPOSED REVISION TO SPECIFICATION 4.6.1.2.a 1

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ENCLOSURE 2 Description of Change TVA proposes to modify the SQN unit 1 technical specifications (TSs) to request a one-time extension of the 40 10-month, Type A, test schedule as described by containment system surveillance requirement (SR) 4.6.1.2.a. The l proposed change would permit the third containment integrated leak rate test (ILRT) to be performed during the unit 1 cycle 4 refueling outage. The current SR 4.6.1.2.a states:

"Three Type A tests (Overall Integrated Containment Leakage-Rate) shall be conducted at 40 t 10 month intervals during shutdown at Pa (psig) during each 10-year service period. The third test of each set shall be l conducted during the shutdown for the 10-year plant inservice inspection."

TVA proposes to add a footnote to allow a one-time extension of the current test interval. The footnote reads as follows: "A one-time extension of the test interval is allowed for the third Type A test within the first 10-year service period provided unit restart following unit 1 cycle 4 refueling  !

outage."

Reason for Change SQN's unit 1 entered its cycle 3 refueling outage on August 22, 1985. On December 15, 1985, unit 1 successfully completed its second periodic Type A test. Unit I returned to power operation on November 10, 1988, following an extended shutdown period. In accordance with the 40 10-month test interval, SQN would be required to perform its third periodic unit 1 Type A test before February 15, 1990 (50 months). Application of the 40 110-month test interval requires TVA to schedule a unit i shutdown sometime during cycle 4 for the sole purpose of performing a Type A test. TVA's current unit 1 cycle 4 schedule does not include a shutdown for the performance of a Type A test.

The only outage currently scheduled during unit 1 cycle 4 is an 8-day outage for conducting an ice condenser flow passage inspection. This outage is scheduled to begin October 1, 1989. This inspection will be conducted while in mode 4 and will involve entering TS limiting condition for -

operation 3.6.5.1 for a 78-hour duration. The inclusion of a Type A test to l 1

this outage would require entry into mode 5. This would add an additional 2 to 3 days for temperature stabilization within containment; 14 days for setup, testing, and recovery; and 5 days for conducting mode 5 surveillance tests.

The additional downtime described above would cost TVA approximately

$2.5 million in replacement power costs. A forced outage for the sole purpose N of performing a Type A test would similarly require a 22-day outage that would require 2-3 days of deadtime for temperature stabilization within i

containment. Based on the above cost options, TVA finds the extension of the i Type A test to coincide with the unit 1 cycle 4 refueling outage to be economically prudent.

The proposed modification to the Type A test schedule is a temporary exemption to the required test interval. The proposed extension of the 40 10-month '

test interval would enable unit 1 to complete its fourth fuel cycle without ,

i requiring a forced shutdown for test purposes. Considering that unit 1 has not experienced any unusual temperature or pressure excursions within the reactor containment building since the last Type A test and considering

l that no modificational have occurred that would have altered containment integrity, TVA finds no reason to suspect degradation in the unit 1 containment during the approximate 3-year shutdown period. It is important to note that the unit 1 containment structure was vented to the atmosphere during the extended outage. This configuration precluded any pressure oscillations ~

that would be expected when the containment structure is in a closed condition (i.e., normal purging and/or venting). TVA investigated the option of pirforming a Type A test before the November 1988 unit i restart. This was discussed with NRC's Office of Special Projects. From these discussions, it' was concluded that performance of two Type A tests within the 3-year extended outage would have imposed undue hardship with little or no compensating increase in the level of quality or safety. For these reasons, combined with the cost in man-hours for planning, scheduling, and conducting a Type A test, TVA requests a one-time exemption from the 40 10-month test interval of unit 1 SR 4.6.1.2.a.

Justification for Change Performance of the 10 CFR 50, Appendix J, Type A test during a forced shutdown would require an unusual set of valve alignments and system configurations for setup and recovery. Performance of an ILRT during the early stage of an outage results in additional downtime required for stabilizing temperature inside containment (i.e., high levels of decay heat within the reactor coolant system). Typically, the Type A tests are performed at the end of a refueling outage to prcelude fluctuations in containment temperature because of decay heat and residual heat within the reactor coolant system. Periodic test scheduling requirements for the Type A tests are provided in 10 CFR 50, Appendix J.Section II.D.1. This section requires that three Type A tests be performed at approximately equal intervals during each 10-year service period. It also states, "The third test of each set shall be conducted when the plant is shutdown for the 10-year plant inservice inspections." This j

10-year milestone would occur at a time when the plant is shut down for refueling. Based on the above requirement, it is clear that Appendix J intended the Type A test schedule to coincide with plant refueling outages.

This is also evidenced within the Types B and C test schedules contained in 10 CFR 50, Appendix J, Sections III.D.2 and III.D.3.

l It is important to note that TVA conducted a complete local leak rate program on all Types B and C penetrations before entry into mode 4 during the November 1988 restart.2 This ensured that all Types B and C containment penetrations were within their acceptance criteria (0.60 La) and would not N I

ITVA's workplan review process under Administrative Instruction (AI) 19

" Plant Modifications After Licensing," part IV, requires the Mechanical Test Section to review all modifications that would affect the containment structure. No workplans were identified with modifications affecting unit 1 containment. '

2By letter dated August 5, 1987, TVA requested exemption from 10 CFR 50, Appendix J, to defer (on a one-time basis) the Types B and C test interval prior to unit I restart. NRC granted approval of TVA's exemption request'in a July 14, 1988, letter.

impact the overall containment leakage limit of 0.75 La. TVA also verified that the structural integrity of the containment steel ve:sel and shield building was maintained during the extended outage. To ;atisfy the requirements of 10 CFR 50, Appendix J, Section V.A, anc JQN TS SR 4.6.1.6 TVA conducted a visual inspection of the containment vessel and shield building prior to mode 4 to ensure no inadvertent damage occurred during~the extended outage. -This inspection was performed to verify that there w re no apparent changes in appearance of the surfaces or other abnormal degradation. This inspection was accomplished in accordance with Surveillance Instruction (SI) 254, " Containment Vessel and Shield Building Integrity Verification," and fulfilled TS SR 4.6.1.6. This inspection fulfilled IVA's letter of commitment dated August 19, 1988, as referenced in Section 3.6.3 of the NRC Safety Evaluation Report for SQN unit i restart (NUREG-1232, Volume 2, Supplement 1).

Since the first Type A test was conducted on unit 1 in March 1979, the overall  !

leakage from unit 1 has remained at very low levels. Based on the test data i (95 percent confidence level) from the two previous Type A tests 3 combined with the preoperational functional test data (0.04008 percent per day

[preoperational), 0.09429 percent per day [ test 1], and 0.05388 percent per day [ test 2]), the unit 1 overall leak rate has consistently remained below 0.10 percent per day (SQN's limit of 0.75 La is equivalent to 0.1875 percent per day). Given these historical margins, combined with the fact that the unit 1 containment has not undergone modifications that affect the containment or have been subjected to any thermal or pressure transients, TVA considers j the proposed change to be justified. j Environmental Impact Evaluation The proposed change request does not involve an unreviewed environmental question because operation of SQN unit 1 in accordance with this change would I not alter any assumptions or information contained in the " Final Environmental Statement" related to the operation of SQN units 1 and'2 dated February 13, 1974.

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Preoperational test data (reference TVA letter to NRC dated July 18,'1979) l represents the baseline leak rate results for SQN unit 1. Test data provided for tests 1 and 2 (reference TVA letters to NRC dated February 17, 1983, and March 4, 1986) represents as-left leak rate values. Test results contained r in the above reports indicate that SQN unit I has been a low-leakage containment.

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I ENCLOSURE 3 PROPOSED TECHNICAL SPECIFICATION CHANGE 1

SEQUOYAH NUCLEAR PLANT UNIT 1 DOCKET NO. 50-327 -

(TVA-SQN-TS-89-11)

DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATIONS ]

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1 ENCLOSURE 3

.l Significant Hazards Evaluation I

1 TVA has evaluated the proposed TS change and determined that it does not represent a significant hazards consideration based on criteria established in 10 CFR 30.92(c). Operation of SQN in accordance with the proposed amendment ,

will not: _ l (1) Involve a significant increase in,the probability or consequences of an accident previously evaluated. The proposed change is a one-time extension of the 40 +10-month, Type A, test interval as contained in I SR 4.6.1.2.a. The purpose of the Type A test is to ensure that leakage through the primary containment and systems and components penetrating primary containment does not exceed allowable leakage rate values as specified in the TSs (SQN's limit is 0.75 La). Because the most likely leakage paths through containment are the penetrations, TVA completed a local leak rate test program on all penetrations and valves requiring Types B and C testing before unit i restart following the unit 1 cycle 3 refueling outage. This ensured that all Type B and C penetrations and valves were within the allowable containment leakage limit of 0.6 La. In addition TVA performed SI-254 to visually inspect the surfaces of the containment liner and the shield building for changes in appearance or other abnormal degradation before unit restart. Performance of these tests, coupled with the fact that unit i remained in cold shutdown ,

condition during an extended 3-year period and did not experience any )

temperature excursions or pressure oscillations since the last Type A j test, ensures that containment integrity was maintained during the 3-year i shutdown period. On this basis, TVA has determined that the extension of I the test interval would not involve a significant increase in the probability or consequences of an accident previously evaluated.-

(2) Create the possibility of a new or different kind of accident from any previously analyzed. No new accident scenarios are created by the proposed change because the one-time extension affects only the test q frequency and does not affect the physical containment structure, t h.e  ;

penetrations, or the facility. Previous Type A test results have shown that the leak rates for unit 1 have remained well below the 0.75-La limit. In addition, the unit 1 containment structure has not undergone modifications or been subjected to thermal or pressure excursions since the last Type A test that would have altered containment integrity.

Because the 0.75-La leakage limit has not been compromised, the requested extension of the test interval will in no way create the possibility of a new or different kind of accident from any previously analyzed.

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(3) Involve a significant reduction in a margin of safety. SQN's unit I was shut down for refueling in August 1985 and has remained in cold shutdown since that time. The second regularly scheduled Type A test for unit I was successfully completed in December 1985. The data from the December 1985 test indicates a significant margin exists between the measured overall leak rate (0.05388 percent per day) and the 0.75-La limit (0.1875 percent per day). Because unit 1 has remained in cold  ;

shutdown and considering that no modifications have been performed on the  !

containment boundary, the observed margin provided by the December 1985 test would not be expected to degrade beyond the 0.75-La leak rate limit. To ensure this margin is maintained. TVA completed-a local leak rate program on all penetrations and valves requiring Types B and C testing before the November 1988 restart. In addition, TVA performed SI-254 to visually inspect the surfaces of the containment liner and the shield building for changes in appearance or other abnormal degradation.

Based on these actions and the previous test margin, the one-time extension of the 40 10-month, Type A, test interval would not involve a significant reduction in the margin of safety.

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. i ENCLOSURE 4  ;

PROPOSED TECHNICAL SPECIFICATION CHANGE SEQUOYAH NUCLEAR PLANT UNIT 1 DOCKET NO.'50-327 i

.(TVA-SQN-TS-89-11) .

REQUEST.FOR EXEMPTION FROM 10 CFR 50, APPENDIX J. SECTION III.D.1.(a) 1 s

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ENCLOSURE 4 REQUEST FOR EXEMPTION FROM 10 CFR 50, APPENDIX J, SECTION III.D.1.(a)

In accordance with 10 CFR 50.12(a)(2)(iii), compliance with 10 CFR 50, Appendix J.Section III.D.1.(a), to perform ~ Type A tests at approximately equal intervals during each 10-year service period would result in undue hardship or other costs that are significantly in excess of those contemplated when the regulation was adopted. It is the intent of 10 CFR 50, Appendix J, to require that three Type A tests be performed at approximately equal intervals during each 10-year service period and that these Type.A tests be performed during shutdowns that would coincide with milestones such as the 10-year inservice inspection refueling outages.

SQN unit 1 entered its cycle 3 refueling outage on August 22, 1935, and 3 successfully completed its second periodic Type A test on December 15, 1985.

Unit 1 remained in a shutdown condition for approximately 3 years before returning to power operation on November 10, 1988. This unusual outage history has resulted in hardship to TVA in complying with the 10 CFR 50,

\ppendix J, Type A, test schedule. Compliance with the 10 CFR 50, Appendix J, rype A, test schedule requires that TVA either achedule a forced unit 1 outage for the sole purpose of performing a Type A test or conduct a Type A test during the ice condenser flow passage inspection outage projected to start October 1, 1989. A forced outage would require 22 days to conduct the Type A test. The estimated cost to TVA would be $2.5 million in replacement power costs. Inclusion of a Type A test during the ice condenser flow passage inspection (8-day duration) would add an additional 22 days to the outage.

Br.ced on the SQN unit 1 unusual outage history (3-year shutdown peried) and the undue hardship and costs that would be required to comply with 10 CFR 50, Appendix J, Section III.D.l(a), TVA is requesting an exemption from Appendix J to allow extension of the Type A testing frequency to coincide with the SQN unit 1 cycle 4 refueling outage. This one-time extension would require that SQN unit 1 shut down no later than May 1, 1990, and that Type A testing be successfully completed before unit restart following unit 1 cycle 4 refueling. This exemption is requested in accordance with I 10 CFR 50.12(a)(2)(iii). -

I Environmental Assessment '

In addition to th's above exemption request, TVA is providing the following environmental assessment and finding of no significant impact.

, Identification of Proposed Action TVA's request for a one-time extension cf the Type A test frequency for SQN unit 1 will require unit shutdown no later than May 1, 1990, and requires performance of Type A testing before unit restart following the unit 1 cycle 4 ,

refueling outage. TS SR 4.6.1.2(a) requires Type A tests be conducted at 1 40 110-month intervals during shutdown within each 10-year service period.

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10 CFR 50, Appendix J.Section III.D.1(a), requires performance of Type A tests at approximately equal intetvals during each 10-year service period.

The need for the proposed extension arose because of the extended unit 1 outage period (3 years) required to address safety concerns at SQN. Under t.he proposed extension, TVA would successfully~ complete Type A testing on SQN unit 1 before restart (mode 4) from the unit I cycle 4 refueling outage. This outage would begin no later than May 1, 1990.

The Nood for the Proposed Action The proposed one-time extension is needed for SQN unit 1 because performance of Type A testing during a forced outage or during an ice condenser -inspection outage would impose undue hardships and cost with no compensating increase in the level of quality or safety.

Environmental Impact. of the Proposed Action

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The proposed one-time extenr, ion of the type a test interval would allow 74 days of additional operation time beyond the TS required 40 110-months test 4 l interval. Considering that the SQN unit 1 containment structure was vented to I the atmosphere during the extended 3-year outage period (this condition l precluded any pressure oscillations that would be expected when the I containment vessel is in a closed condition) and considering that TVA conducted a complete local leak rate program (Types B and C penetrations) and performed a complete visual inspection of the containment vessel before unit i restart, TVA finds no apparent reason to suspect that containment integrity would be compromised under the proposed extension. TVA thereby concludes that the proposed one-time extension of the Type A test interval would not involve a significant environmental impact.

Alternative to the Proposed Action The alternative to the proposed one-time extension of the Type A test interval would be to perform the Type A testing in accordance with the required TS test interval (the 40 110-month test interval expires January 22, 1990). This alternative would require a forced outage sometime during cycle 4 for the solo purpose of performing a Type A test. This alternative would impose undue ~

harduhip and costs to TVA with little or no compensating increase in the level of quality or safety.

Alternative Use of Resources The one-time extension of the Type A test interval for SQN unit 1 does not 1 involve the use of resources not previously considered in connection with the

" Final Environmental Statement" related to the operation of SQN units 1 and 2 f

, dated February 13, 1974.

1 Findinn of Uo Significant Tapact I 1

l TVA finds no basis for preparing an environmental impact statement for the proposed one-time extension of the SQN unit 1 Type A test interval. Based on ,

the above environmental assessment, we conclude that the proposed exemption will not have a significant offect on the quality of the human environment.

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