IR 05000259/1991012

Insp Repts 50-259/91-12,50-260/91-12 & 50-296/91-12 on 910315-20.No Violations Noted.Major Areas Inspected:Test Procedures,Test Preparation,Test Performance & Test Results of Primary Containment Integrated Leak Rate Test

ML20138G104
Person / Time
Site:	Browns Ferry
Issue date:	04/16/1991
From:	Jape F, Whitener H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20138G102	List: IR 05000259/1991012 ML20138G096
References
50-259-91-12, 50-260-91-12, 50-296-91-12, NUDOCS 9610180227
Download: ML20138G104 (8)

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• /g# #810q'o UNITE) STATES

[ NUCLEAR REGULATORY COMMISSION n REGION il l, g j

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1. 101 MARIETTA STREET, #

ATLANTA, GEORGI A 30323 s,...../

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Report No /91-12, 50-260/91-12, and 50-296/91-12 Licensee: Tennessee Valley Authority l 6N 3SA ' ookout Place

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1101 Market Street Chattanooga, TN 37402-2801 Docket Nos.: 50-259, 50-260 and 50-296 License Nos.: DPR-33, DPR-50, l and DPR-68 Facility Name: Browns Ferry 1, 2. and 3 Inspection Conoucted: Maren 15-20, 1991 i

Inspector: $

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H. L. Whitener ~

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' Date Signed l Approved by:

//d#f F. Jape, Chief ~

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Test Programs Section Date Signed Engineering Branch Division of Reactor Safety SUMMARY Scope:

This routine, primary announced containment integra tedinspection was conoucted in the areas of witnes proceoures, test preparation, test performance and test results. leak rate Results:

In the areas inspected, violations or deviations were not identifie The Rate licensee had developed a thorough and detailed Containment

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Test Integrated Leak i requirements and cetailed pre-planning for test preparation i Management involvement was evident in the development of procedures and an .

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expanded test organization which provided adequate support j containment was demonstrated to be leak tign for tne test. The the da upper confidence limit (incluces probable The calculated error) was 0.258leak rate for percent weight per 1.5 weightThis is approximately percent per da percent of the allowable leakage limit of Two concerns were identified curing this insoection: (1) the reactor building to torus vacuum breaker system air r operated cutterfly valves opened on pressure rather than on vacuum and; 9610180227 960416 PDR G ADOCK 05000259 PDR ,

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(2) certain ventilation

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leakage problems during a local leak rate test. system air operated butterfly valves s a are discussed in paragraph 3 of this repor Resolution of these concerns i

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REPORT DETAILS Persons Contacted Licensee Employees

• * Austin, Mechanical Engineer, Compliance Clark, Supervisor, Corporate Maintenance L. Farmer, Engineer, Corporate Maintenance C. Miller, Engineer, Corporate Maintenance M. Morrison, Engineer, Compliance

• L. Myers, Plant Manager

• "J. Nilsen, Engineer, Engineering Support Shaw, Supervisor, Engineering Support Other licensee engineers, employees operators, contacted during this inspection included and technician NRC Resident Inspectors

• Patterson, Senior Resident Inspector W. Bearden, Resident Inspector E. Christnot, Resident Inspector K. Ivey, Resident Inspector i

" Attended exit interview

< Containment Integrated Leak Rate Test (70313)

The to inspector determine thatreviewed test documentation and witnessed test activit test the Unit 2 primary containment integrated leak rate Primary (CILRT) was performed in accordance with 10 CFR 50, Appendix J, Reactors;Reactor Containment Leakage Testing For Water-Cooled Power ANSI-45.4-1972, Leakage-Rate Testing of Containment Structures for Nuclear Reactors; Technical 2-SI-4.7. A.2.a-f, Primary ContainmentSpecification 4.7. A.2; test procedure Integrated Leak Rate Test; and, of Primary Containment Structures for Nuclear Poweri Selected sampling of the licensee's included: activities which were inspected was properly (1) review of the test procedure to verify that the procedure !

approved and conforms with the regulatory requirements !

listed above; (2) observation of test performance to determine that tes}!

prerequisites were completed, special equipment was installed, and appropriate data were recorded; and (3) preliminary evaluation of leaka rate test results to verify that leak rate limits were me aspects of the test are discussed in the following paragraphs. Pertinent ;

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l l General Observations

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The inspector witnessed and/or reviewed portions of the test preparation, containment pressurization, and temperature stabilization, data processing during March 15-20, 199 were inspected: The following items t (1)

The test was conducted in accordance with an approved procedure l

maintained at the test control center.

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changes to the procedure were properly documented, Test discrepanci

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! (2) Selected completed.test prerequisites were reviewed and found to be

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l Selected plant systems, required to maintain test control, were reviewed and found to be operationa (4) Special test instrumentation was reviewed and found to be installed.

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Data required for the performance of the containment leak rate i calculations were recorded at 10-minute interval (6)

Events event encountered during the test were described in the test lo (7)

Pressurized gas sources were reviewed for proper isolation and through containment isolations valves. venting to preclude (8)

draining.Certain system alignments were reviewed to verify venting i

No violations were identified in the above area Procedure Review, Unit 2 (70307)

Review of 2-SI-4.7.A.2.a-f showed that adequate test controls, instructions and acceptance criteria are specifie Acceptance criteris are for include both the short duration (8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />) and the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> te instructions are included as attachments to the procedure Also, systems in procedur service and the add on leakages are specified in the acceptabl The inspecter concluded that the procedure was Other

included: instructions or procedures reviewed for the d

leak rate test t

Technical Revision 1. Instruction 2-TI-173, Primary Containment Inspection,

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Technical Instruction 2-TI-179, CILRT Data Acquisition System Setup, Revision 0.

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! Containment Temperature Survey Test Performance (1) Method t

The containment integrated leak rate analysis program of TVA has the capability of analyzing the data in accordance with the requirements of BN-TOP-1 for a short duration test or in Containment tes System Leakage Testing Requirements for a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> For thethe Consequently, Unit 2 test, the data met the BN-TOP-1 criteri BN-TOP-1 analysis for a short duration test. licensee used the The mass point analysis method was simultaneously calculate (2) Description Containment March 17, 1991,pressurization was initiated at 2305 hours0.0267 days <br />0.64 hours <br />0.00381 weeks <br />8.770525e-4 months <br /> on subsequent to final containment inspectio The following sequence of events was taken from the test log:

Date Time Condition 3/17 2305 2315 Air compressors starte Inboard reactor building to Torus Vacuum breaker valves opened at 1.5 psig. The outboard check valves held the pressur /18 0511 0537 One air compressor shutdow Pressurization terminated at 0555 50.46 psi Compressors isolated from 0715 containment and vente Leak checking in accordance with TI-173 initiated. No significant leakage was 0751 identifie Stabilization period starte /19 1201 i

Stabilization period terminate Temperature criteria me _ _ . .. _ - . . _ , . . ._. -

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First data point for the

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Eight hour Type A test ( terminated.

! 2151 Verification test started !

0151 after one hour stabili:atio '

Four hour verification test 0530 terminate Began depressurization of containmen (3) Test Results - Unit 2 i (a) Type A Test  !

Technical specification allowable leakage (La) for Browns Ferry Unit 2 is 2.0 weight percent per day. Therefore, the ( integrated leak rate test leakage limit of 0.75 La as required by Appendix J is 1.5 percent per day.

I The following measurement are the results of the eight hour leak rate l'

and the leak rate compensated for error (95

percent Upper Confidence Limit) for both the Mass Point (MP) analysis according to ANSI /ANS 56.8 and total time  ;

(TT) analysis according to BN-TOP-1: i

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Measured Leak Rate Upper Confidence Limit

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MP 0.234 wt.% per day i'

TT 0.234 wt.% per day 0.238 wt.% per day 0.258 wt.% per day The inspector's calculated values agreed closely with licensee calculation (b) Supplemental Test - Unit 2

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l Appendix J requires that a supplemental test be performed

, of rat the CILRT instrumentation to measure a chan{ '

l The following is an acceptable supplemental test method as described in Appendix C of ANSI N45.4 - 197 A known leak rate (Lo) is imposed on the containment and the measured composite leak rate (Lc) must equal, within 10.25 La, the sum of the measured leak rate (Lam) plus the  !

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known leak rate (Lo).

The acceptance criteria is expressed as:

Lo + Lam - 0.25 La < Lc < Lo + Lam + 0.25 La

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' 1 A four hour verification test was performe The following I day): measured values were obtained (Units are in wt. percent per II MP LAM 0.234 0.234 Lo 1.67 1.67 Lc 2.26 0.25 La 2.27 .5 Substitution of these values into the acceptance criteria

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shows that the inequality equation was satisfied as follows:

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Mp 1.404 < 2.26 < 2.404

!- 1.404 < 2.27 < 2.404 The inspector concluded that the verifi .ation test confirmed the instrument system capability to measure the containment leak rat (d) Type A Test Status The Unit 2 Type A test was classified as a failed test.(CIRLT) performed in February 1983 Since this was the first

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failed Type A test the NRC allowed Unit 2 to remain on a 401 10 month CIRLT schedule. The decision to keep Unit 2 shutdown indefinitely was made while the unit was in an outage in 1985 for which no Type A test was schedule The inspector concluded that due to the extended outage and numerous modifications, the Type A test just performed s.

would leak ratebe penalty treated as a preoperational test and no "as found" applied.

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rate must be determined for future Type A tests.However, The plant the remains on a 401 10 month test schedul .

! Concerns Relating to Leak Rate Testing (61720)

! Reactor Building to Torus Vacuum Breaker the reactor building atmosphere with the torus

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outer inch air 20 inch butterfly operated check valve valve. and an inner (closest to contain i

allow air vacuum in flow from the building to the torus in the event the toru of aThe ch

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differential pressure between The air operated butterfly valve opens on reactor building and toru This-design provides double isolation barriers against containment leak if the containment torus from negative pressure.is at pressure and vacuum relief to protect the

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During the CILRT the opposite to its intended function. inner valve appeared to operate in a manner The butterfly valves in the two

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systems, 64-20 and 64-21, opened at 1.5 psig when pressurizing the containment and closed at 0.6 psig when depressurizing containment.

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7 The inspector informed licensee management at the exit interview that a the Resident Inspectors will follow this matte Ventilation System i

Just prior to the CILRT a local leak rate test was performed which involved valves leak testing five ventilation system air operated butterfly simultaneousl Significant leakage was identified. In attempting to identify and repair the leaking valves, the licensee cycled . certain valves with the result that leakage increased dramaticall penetrations 26The andlicensee 231 weredeterminedleak ti that the inner valves far between the inner and outer valves, ght and elected to open vents the inner valves during the CILRT. thereby The taking credit for only repaired and locally tested before startup. leaking valves will be Since ventilation system valves have a leakage problem history, the inspector asked licensee management leakage performancewhat corrective of these valves. action will be taken to improve the Management indicated that the valve performance will be pursued and resolved. The options available are being evaluate replacement of these Included in these options is possible valves with valves of improved design and leakage desig characteristics or rebuilding the current valves to improve This matter. will be reviewed during future leak rate inspection . Exit Interview The inspection scope and results were summarized on March 20, 1991, with those persons indicated in paragraph inspected Proprietary and discussed in detail the inspection results listed below information is not contained in this repor Dissenting comments were not received from the license *

The by theinspector CILRT. stated that a leak tight containment was demonstrated

The inspector discussed two identified concerns as follows:

(a) vacuum vacuum breaker signal. system valves opening on a pressure rather than a (b) ventilation system valve leakage problem The licensee has agreed to investigate and resolve these concern ..L

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