ML18039A817

LER 99-007-00:on 990623,discovered That SR for Monitoring of Primary Containment Oxygen Concentration Had Not Been Met. Caused by Failure of Operators to Adequately Communicate. Required Surveillances Were Performed.With 990720 Ltr

ML18039A817
Person / Time
Site:	Browns Ferry
Issue date:	07/20/1999
From:	Herron J, Rogers A TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-99-007, NUDOCS 9907270243
Download: ML18039A817 (20)

Text

~ CATEGORY 4 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RZDS)

ACCESSION NBR:9907270243 DOC.DATE: 99/07/20 NOTARIZED: NO DOCKET FACZL:50-260 Browns Ferry Nuclear Power Station, Unit 2., Tennessee 05000260 AUTH.NAME AUTHOR AFFILIATION ROGERS,A.T. Tennessee Valley Authority HERRON,J.T. Tennessee Valley Authority RECIP.NAME'ECIPIENT AFFILIATION

SUBJECT:

LER 99-007-00:on 990623,discovered that SR for monitoring of primary containment oxygen concentration had not been met.

Caused by failure of operators to adequately communicate.

Required surveillances were performed. With 990720 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES 0 ID CODE/NAME LTTR ENCL ID'ODE/NAME LTTR ENCL LPD2-2 PD 1 1 LONG,W 1 1 INTERNAL: ACRS 1 1 ILE C 1 1 NRR/DZPM/IOLB 1 1 REXB 1 1 NRR/DSSA/SPLB 1 1' RES/DE//ERAB 1 1 RES/DRAA/OERAB 1 RGN2 FILE 01 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LMITCO MARSHALL 1 1 NOAC POORE,W. 1 1 NOAC QUEENER, DS 1 1 NRC PDR 1' NUDOCS FULL TXT 1 1 D C'

NOTE TO ALL "RIDS" RECZPZENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD) ON EXTENSION 415-2083 1

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER'F COPIES REQUIRED: LTTR 16 ENCL 16

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Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609.2000 John T. Herron Interim Vice President, Browns Ferry Nucfear Rant July 20, 1999 U.S. Nuclear Regulatory Commission 10 CFR 50.73 ATTN: Document Control Desk Washington, D. C. 20555

Dear Sir:

BROWNS FERRY NUCLEAR PLANT {BFN) UNITS 2 AND 3 DOCKET NOS.

50-260 AND 296 FACILITY OPERATING LICENSE DPR-52 AND 68 LICENSEE EVENT REPORT {LER) 50-260/1999007 The enclosed report provides details concerning an event where the Technical Specifications surveillance requirements were not being met.

This condition is reportable in accordance with 10 CFR 50.73 (a) (2) (i) (B) as a condition prohibited by .the plant' technical specifications.

Sincerely, John T. Herron In crim Site Vice President cc See page 2

'tf'tf07270248 990720 0500026 PDR ADOCK

U.S. 'Nuclear Regulatory Commission Page 2 July 20, 1999 Enclosure cc (Enclosure):

Mr. William O. Long, Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. Paul E. Frederickson, Branch Chief U.S. Nuclear Regulatory Commission Region II Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, Georgia 30303-3415 NRC Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611

il U.S. Nuclear Regulatory Commission Page 3 Jul'y 20, 1.999 TEA'GMM'ATR'BAB Enclosure cc (Enclosure):

J A. Bailey., LP 6A-C

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=M. J. Burzynski, BR 4X-C E. S. Christenbury, ET 11A-K C. C. Cross, LP 6A-C R. G. Jones, POB 2C-BFN J. Scott Martin, PMB 1A-BFN F. C. Mashburn, BR 4X-C R. P. Greenman, PAB 1C-BFN C. M. Root,, PAB 1G-BFN J. A. Scalice, LP 6A-C K. W. Singer, LP 6A-C R. E. Wiggall, PEC 2A-BFN NSRB Support, LP SM-C EDMS, WT 3B-K

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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EKPIREs (6-19981 OerscnOO1 Estimated burden per response to comply with this mandatory hformation collection request: 50 hrs. Reported lessons learned are Incorporated into LICENSEE EVENT REPORT (LER) the Ecensing process and fed back to industry. Forward comments egarding burden estimate to the Records Management Branch (TA F33). U.S.

Nudear Regrdatory Conrmission. Washingtorl OC 205550001, and to the (See reverse for required number of Paperwork Reduction Project (31500104). Once of Management and digits/characters for each block) Budget. Washirxrton, OC 20503. If an informstbn ooBecUon does not display a currently vahd 0MB control number. the NRC may not conduct or sponsor, and a person Is not required to respond to. the hformadon cosset ion.

FACIUTY NAME ill DOCKET NUMBER I2) PAQE (31 Browns'Ferry Nuclear, Plant Unit 2 05000260 1 of6 t

TITLE (41 Surveillance Requirement Not Met For Monitoring of Primary Containment Oxygen Concentration EVENT DATE (SI LER NUMBER (6) REPORT DATE (7) OT ER ACI IT S 0 IB)

MONTH DAY YEAR YEAR, SEQUENTIAL REVISION A ILI DOCKET NUMBER NUMBER NUMBER Browns Ferry Unit 3 05000296 DOCKET NUMBER 06 23. 99 1999 007 000 20 99 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5: (Chock ono or mora) (11)

MODE (9) 1 20.'2201(b) 20.2203(a) (2) (v) 50.73(a)(2)(i)(B) 50,73(a) (2)(viii)

POWER 20.2203(a) (1) 20.2203(a)(3)(i) 50.73(a) (2) (ii) 50.73(a) (2) (x)

LEVEL (10) 100 20.2203(a) (2) (i) 20.2203(a)(3)(ii) 50.73(a) (2) (iii) 73.71 20.2203(a) (2) (ii) 20.2203(a) (4) 50.73(a)(2)(iv) OTHER 20.2203(a) (2) (iii) 50.36(c)(1) 50.73(a) (2) (v) Specify in Abstract below or In NRC Form 366A 20.2203(a) (2)(iv) 50.36(c)(2) 50.73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER tircsrde Ares Cede)

Anthony T.'Rogers, Senior Licensing Project Manager (256) 729-2977 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

SYSTEM COMPONENT MANUFACTURER REPORTABLE TO CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE NPRDS TO NPRDS NA SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH OAY YEAA YES NO SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE).

X DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

The Surveillance Requirements (SR) of Technical Specification (TS) 3.6.3.2, Primary Containment Oxygen Concentration require the primary containment oxygen concentration be verified below four percent by volume to ensure the containment remains inerted. Each unit has two oxygen analyzers, one that is normally aligned to the drywell and the other aligned to the suppression chamber. The 3B oxygen analyzer had become inoperable and in order to satisfy the SR, plant procedures require, the operable monitor be manually aligned to verify both the drywell and suppression chamber are within limits as required on a seven day frequency. However on June 23, 1999, it was discovered that the SR was not being met since the operable analyzer was aligned to the drywell and no valid data had been collected or recorded for the suppression chamber in the past seven days. Further investigation revealed the same SR was not being met on Unit 2 since the operable analyzer had not been aligned to the suppression chamber within the last 7 days.

Upon discovery of the failure to meet the requirements of SR 3.6.3.2.1, a 24'hour TS Limiting Condition for Operation (LCO) was entered for each unit until a valid sample was obtained. The root cause of the event was failure of the operators (utility-licensed) to adequately communicate and track the status of the inoperable oxygen sample pumps. There were no actual or potential safety consequences as a result of this event nor did this event adversely affect the safety of plant personnel or the public.

This condition is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the plant's Technical Specifications.

NRC FORM 366B (6-1998)

il NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-I 998I LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITYNAME 1 DOCKET LER NUMBER 6 PAGE 3 YEAR SEQUENTIAL REVISION NUMBER 2 of 6 Browns Ferry Nuclear Plant - Unit 2 05000260 1999 007 " 000 TEXT ilfmore space, is required, use edditionel copies of itiRC Form 366A/ i17I I. PLANT CONDITION(S)

At.the time of the discoveryof.this condition, Unit 2 and Unit 3 were operating at 100.percent power, and Unit 1 was shutdown and defueled.

II. DESCRIPTION OF EVENT A.:Event:

The SR of TS 3.6.3.2, Primary Containment Oxygen Concentration requires the primary containment oxygen concentration be verified below four percent by volume to ensure the containment remains inerted. Each unit has two oxygen analyzers, one that is normally.aligned to the drywell and the other aligned to the suppression chamber. Each oxygen analyzer is a sub-component of a hydrogen/oxygen (H202) analyzer system. The-38 oxygen analyzer had become inoperable and in order to satisfy the SR, plant procedures require the operable monitor be manually aligned to verify both the.drywell and suppression chamber are within limits as required on a seven day frequency. However on June 23, 1999,.it was discovered that the SR was not being,met since the. operable analyzer was aligned to the drywell and no valid data had been collected or recorded for the suppression chamber in the past seven days. Further, investigation revealed the same SR was not being met on Unit 2 since the operable analyzer had not been aligned to'the suppression chamber within the last 7 days.

Upon discovery of the failure to meet the requirements of SR 3.6.3.2.1, a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> TS LCO was entered for each unit until a valid sample was obtained.

These conditions applied to both Units 2 and 3. This condition is reportable in accordance with 10.CFR:50.73(a)(2)(i)(8) as a condition prohibited by the plant's Technical Specifications (TS).

'B. Ino erable Structures Com onents or S stems that Contributed to the Event:

28 and 38 Oxygen Analyzers inoperable.

C. Dates and A roximate Times of Ma or Occurrences:

May 8; 1999 Last valid reading taken, for suppression chamber oxygen concentration on Unit 3.

May 12, 1999 1715 hours0.0198 days <br />0.476 hours <br />0.00284 weeks <br />6.525575e-4 months <br /> CST Maintenance personnel found the 38 Oxygen Analyzer Inlet Pump not operating. Corrective maintenance initiated.

May 13,,1999'925 hours0.0107 days <br />0.257 hours <br />0.00153 weeks <br />3.519625e-4 months <br /> CST Caution order placed on the 3A H202 Analyzer which identifies it as the only operable analyzer.

June 12, 1999 Last'valid reading taken for suppression chamber oxygen concentration on Unit 2.

June 17, 1999 2130 hours0.0247 days <br />0.592 hours <br />0.00352 weeks <br />8.10465e-4 months <br /> CST 28 H202 analyzer declared inoperable due to water in the sample lines. Corrective maintenance initiated.

NRC FORM 366 I6-1998)

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NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I6-1998I LlCENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME 1 DOCKET LER NUMBER 6 PAGE 3 YEAR SEQUENTIAL NUMBER 3 of 6 Browns Ferry Nuclear Plant - Unit 2 05000260 1999 - 007 000 TEXT ii!more spece is required, use eddidonel copies oi NRC Form 366Ai I17)

C. Dates and A roximate Times of Ma'or Occurrences continued:

June 18, 1999 Caution order placed on the 28 H202 Analyzer which requires it to remain out of service until corrective maintenance is completed.

June 23, 1999 1015 hours0.0117 days <br />0.282 hours <br />0.00168 weeks <br />3.862075e-4 months <br /> CST Operations personnel determined that TS SR was not being met on Unit 3 since the operable analyzer had not been aligned to the suppression, chamber to obtain

~ an oxygen sample within the last seven days. Entered 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> TS LCO.to obtain the required oxygen sample in accordance with SR 3.0.3.

June 23, 1999 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> CST Operations personnel determined that TS SR was not being met on Unit 2 since the operable analyzer had not been aligned.to the suppression chamber to obtain an oxygen sample within the last seven days. Entered 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> TS'LCO to obtain the required oxygen sample in accordance with SR 3.0.3.

June 23, 1999 1150 hours0.0133 days <br />0.319 hours <br />0.0019 weeks <br />4.37575e-4 months <br /> CST Aligned the 2A H202 Analyzer to the suppression chamber and obtained the required sample. Exited the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> TS LCO on Unit 2.

June 23, 1999 121 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> CST Aligned the 3A H202 Analyzer to the suppression chamber and obtained the required sample. Exited the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> TS LCO on Unit 3.

D.'ther S stems or Seconda Functions Affected None.

E. Method of Discove These conditions were discovered by the Shift Technical Advisor during the periodic review of procedure SR-2, Instrument Checks and Observations which documents the SR specified by TS 3.6.3.2.

F. 0 erator Actions This event resulted from a cognitive error by the operators (utility-licensed) to adequately communicate and track the status of the inoperable sampling systems. Upon'discovery of this condition, a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> LCO was entered until the requirements of the SR were met for Units 2 and 3.

G. Safet S stem Res onses None.

NRc FDRM 366 (6-1998I

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'J NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION

~ (6 19981 LlCENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME 1 'DocKET LER NUMBER 6 PAGE 3 YEAR SEQUENTIAL REVISION NUMBER 4 of 6 Browns Ferry Nuclear Plant - Unit 2 05000260 1999 007 000 TEXT (lfmore spece is required, use edditionel copies of NRC Form 366A/ (17)

III. CAUSE OF THE EVENT A. Immediate Cause The requirements of SR 3.6.3'.2.1 to.verify primary containment oxygen concentration every 7 days had not been.met.

B. Root Cause The root cause of this event was failure of the operators to adequately communicate and track the status of the inoperable oxygen sampling system.

IV. ANALYSIS OF THE EVENT Two cases of an SR not being met were found by operations personnel during a periodic review of SR-2, Instruments Checks and Observations. In each case, once on Unit 2 and once on Unit 3, a containment oxygen analyzer was inoperable. This condition alone did not result in failure to meet the SR. However, with one. of the analyzers inoperable, plant procedures allow either alternate sampling or operator manipulation of controls. This'provides the operator allowance to align an operable analyzer to either the diywell or suppression chamber..However, the operator performing the 7 day verification, did not,realign the operable analyzer to the suppression chamber and a valid reading for the suppression chamber was not obtained. In each case, the inoperable analyzer was providing a comparable,recordable reading although it would not be valid without a sample pump in service.

Upon, recognition of this condition, a valid sample was obtained for the suppression chamber on both Unit 2 and 3. The procedure used to document these results has been revised to ensure a valid reading is obtained from the diywell and suppression chamber from each operable analyzer every 7 days as required.

V. ASSESSMENT OF SAFETY CONSEQUENCES In normal operation, the primary containment atmosphere is maintained at less than four percent oxygen by.

volume,,with the balance nitrogen. The calculations for a loss of coolant accident, as described in the Final Safety Analysis Report, assume that the primary containment is initially inerted. Thus, the hydrogen assumed to be released to the primary containment as a result of metal water reaction in the reactor core will'not produce combustible,gas mixtures in the primary containment. Oxygen, which is subsequently generated by radiolytic decomposition of water, is diluted and removed by the Containment Air Dilution System more rapidly than it is produced. These are the only significant sources of hydrogen and oxygen. If the concentrations of hydrogen and oxygen were not controlled, a combustible gas mixture could be produced: To ensure that a combustible gas mixture does not form, the oxygen concentration must be kept below five percent by volume, or the hydrogen concentration kept below four percent by volume. During normal operation, TS require the primary containment be incited such that the oxygen concentration is maintained less, than four percent by volume. Therefore, a combustible mixture cannot be present in the primary containment for any hydrogen concentration. The oxygen concentration monitors provide the ability to monitor oxygen concentration from the main control room. The LCO for Primary Containment Oxygen Concentration requires the primary containment oxygen concentration to be less than four percent by volume and the SR requires the concentration be verified within limits every 7 days in both the drywell and NRC FORM 366 I6-1998)

NRC FORM 366A U.s. NUCLEAR REGULATORY COMMISSION (6-1996)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME 1 DOCKET LER NUMBER 6 'PAGE 3 YEAR SEQUENTIAL REVISION NUMBER 5 of 6 Browns Ferry Nuclear Plant - Unit 2 05000260 1999 007 000 TEXT (If more spacois required, use additional copies of'NRC Form 366A/ I17)

V. ASSESSMENT OF SAFETY CONSEQUENCES (continued) suppression chamber. The. frequency is based:on the slow rate at which oxygen concentration can change and on other indications of abnormal conditions which would lead to more frequent checking by operators in accordance with plant procedures.

Each Hydrogen/Oxygen Analyzer (H202) consists of independent oxygen and hydrogen sample inlet pumps, filter/coaiescers, traps, valves, and analyzers. Each analyzer. can function independent of the other provided the flow path and single sample return pump is operable. During the period when the suppression chamber oxygen was not being sampled, on Unit 2 and 3, the oxygen analyzers were sampling the drywell.

At no time was the oxygen concentration found to be above the requirement of four percent by volume in the drywell. Upon discovery of the missed SR, a sample was obtained for the suppression chamber on Unit 2 and 3. The results were, verified to be within limits and recorded, as required. Therefore, it can be concluded that at no time was the oxygen concentration ever above the limits in the suppression chamber.

Furthermore, since the drywell is maintained at'a higher pressure with respect to the suppression chamber

.by the Delta P air.compressor, adequate mixing of the diywell.and suppression chamber can be assured during the entire period while the SR was not being met.

There were no actual or potential safety consequences as a result of this event. For the reasons stated above, this event did not adversely affect the safety of plant personnel'or the public.

VI. CORRECTIVE ACTIONS

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A. Immediate Corrective Actions Entered a 24.hour TS LCO in accordance with SR 3.0.3 and performed surveillance requirements for both Unit 2 and 3.

B. Corrective Actions to Prevent Recurrence The procedure used to document oxygen concentration was revised to require samples from both the drywell and suppression chamber from any operable analyzer weekly.

AII licensed personnel were'briefed on this event.

A tracking mechanism will be developed to track TS equipment compensatory actions.

expectations were reviewed with licensed personnel. 'anagement VII. ADDITIONALINFORMATION A. Failed Com onents None.

'VAdoes not consider. this corrective action a regulatory commitment. The completion of this item will'be tracked in TVA's Corrective Action Program.

NRC FORM 366 I6-1698)

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NRC FORM 366A 'U.S. NUCLEAR REGULATORY COMMISSION (6. (99SI LICENSEE EVENT REPORT (LER}

TEXT CONTINUATION FACILITY NAME 1 DOCKET LER NUMBER 6 PAGE 3 YEAR SEQUENTIAL NUMBER 6 of 6 Browns Ferry Nuclear Plant - Unit 2 05000260 1999 007 000 TEXT Iffmore spaceis required. use addidonal copies of NRC Form 366AJ (17)

B. Previous'LERs on Similar Events LER 260/97004 documented a TS surveillance which was missed. The root cause was determined to be ineffective control of outage schedules. Therefore, the corrective actions for that event would not have prevented this missed surveillance requirement.

LER 259/1998001 documented non-compliance with ANSI standard requirements for Standby Gas Treatment system HEPA filter testing which resulted from improper procedure revisions.

The corrective actions for this condition would not have prevented this missed surveillance requirement.

LER 259/1999002 documented an inadequate surveillance instruction for calibration of Standby Gas Treatment Train B relative humidity control heater flow switches due to technical inaccuracies in the surveillance instruction. The corrective actions for this condition would not have prevented this missed surveillance requirement.

LER 260/97002 documented, an inadequate surveillance, procedure, discovered during a review associated with Generic Letter 96-01. The corrective actions for this condition would not have prevented this missed surveillance requirement.

L'ER 260/296/1998004 documented improper implementation of SR requirements for drywell inleakage,and Average Power Range Monitors voter checks due to misinterpretation of the requirements and procedural inadequacies. The corrective actions for this condition would not have prevented this missed surveillance requirement.

LER 260/1999002 documented failure'to perform the required 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> check of all control rods inserted due to misinterpretation of the'SR resulting from an inadequate procedure. The corrective actions for this condition would not have prevented this missed surveillance requirement.

No other LERs were identified where a'SR was not met. This event was the result of improper tracking and statusing of an out'of service piece, of TS equipment which in and:of itself did not invoke any action LGO or require any compensatory measures for oxygen sampling. Therefore, it is unlikely any of the past corrective actions would have prevented this event.

C. Additional Information None.

D. Safet S stem Functional Failure:

This event did not result in a safety system functional failure in accordance with NEI 99-02.

Vill; COMMITMENTS

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None.

NRC FORM 366 (6.1998(

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