ML18053A561

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LER 88-012-00:on 880808,steam Generator Tube Leakage Noted. Cause Undetermined.Eddy Current Testing in Progress & Supplemental Rept Discussing Test Results,Cause of Failure & All Planned Corrective Actions Will Be Submitted
ML18053A561
Person / Time
Site: Palisades Entergy icon.png
Issue date: 09/06/1988
From: Johnson B, Kozup C
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
LER-88-012, LER-88-12, NUDOCS 8809140150
Download: ML18053A561 (5)
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Text

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LICINllll CONTACT 11011 TMll Liii 1121 I0.711alllll. .1181 I0.7JCall211*1 Informational NAMI TIL.,HONI NUMlllll AlllA COOi C S Kozup, Technical Engineer, Palisades 6 I 11 6 7 I 61 4 1- I 81 9 11 13

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  • I.&. _ _.,, fl'- I I , , . . _ ry~""" liMBJ 1111 Abstract On August 8, 1988 at 1308 the Shift Supervisor was notified by Plant Chemistry that the calculated primary to secondary leak rate was at 0.31 gpm. An Unusual Event was declared at 1310. Due to a concern that previous leak rate calculations had been in error and the leak may have existed for some time, Plant shutdown was commenced at 1315. The Plant was operating at 95 percent power at the time of the event.

Technical Specification 3.1.5.d indicates that "the primary to secondary leak rate in a steam generator [AB;SG] shall not exceed 0.3 gpm for any period of steaay state operations greater than 24 consecutive hours".

Although a subsequent investigation determined that the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> action requirement had not been exceeded, the Plant was brought to hot standby at 1835 on August 8, hot shutdown at 2145 on August 8 and cold shutdown at 0405 on August 10.

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111-131 LER 88012-L!Ol

NRC Form JllA U.S. NUCLEAR REGULATORY COMMISllON 19-831 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVED OMB NO. 3150--0104 EXPIRES. 8/31185 FACILITY NAME 111 DOCKET NUMHR 121 LEll NUMHR 181 PAGE Ill YEAll llEVISION NUM E ..

PALISADES NUCLEAR PLANT 8 osooo25 0 0 0 2 OF 0 4 TEXT (/f - - ii t9qClitw/, . , . <<ldlllotrel NltC Fann .-.C '1J 1171 Description Listed below is the sequence of events leading up to the August 8, 1988 Plant shutdown. The Plant was operating at 95 percent steady state power during this sequence.

August 4, 1988 at 1405: Condenser off-gas radiation monitor RIA-0631

[SH;RI] alarmed in the Control Room. Off-gas activity had increased to 1287 cpm from a previous average of 750 cpm.

August 4, 1988 at 1415: The off-gas monitor reading increased to 15.240 cpm.

August 4, 1988 at 1420: Plant Operations requested that Chemistry sample the condenser off-gas.

August 4, 1988 at 1445: The off-gas monitor reading had increased to 176,900 cpm. Operations requested a second off-gas sample.

August* 4, 1988 at 1508: Operations requested that Chemistry sample both steam generators [AB;SG].

August 4, 1988 at 1515: It was determined that a steam generator tube leak had occurred which was estimated to be 0.004 gpm based on the first condenser. off-gas sample.

August 4, 1988 at 1620: Results of the second off-gas sample indicated a 0.010 gpm primary to secondary leak.

Operations requested a primary coolant system sample.

August 4, 1988 at 1700: The third off-gas sample indicated a 0.022 gpm leak~

August 4, 1988 at 1755: A fourth off-gas sample indicated a 0.027 gpm

- leak.

August 4, 1988 at 1826: Results from the primary coolant system sample, drawn at 1650, indicated no increase in primary coolant activity.

August 4, 1988 at 1915: Operations requested condenser off-gas and steam generator samples for radioactivity taken every two hours.

August 4, 1988 at 2000: Condenser off-gas radiation monitor RIA-0631 reading 290,200 cpm.

N .. C FOlllJM 389A 19.a31 LER 88012-LIOl

NRC Form JNA U.S. NUCLEAR REGULATORY COMMISSION 19-831 LICENSEE EVENT REPORT (LERI TEXT CONTINUATION APPROVED OMB NO. 3150--0104 EXPIRES: 8131185 FACILITY NAME f1I DOCKET NUMSEFI 121 LEll NUMHll 181 PAGE 131 PALISADES NUCLEAR PLANT 0 15 I 0 I 0 I 0 I 215 15 s, s - 011 I 2- 0 I 0 0 I 3 OF 0 14 TEXT /If - _ . ia ,..,,_, - _ . . , NllC Fonn -.C'1I 1171 August 5, 1988 at 0300: RIA-0631 reading 318,400 cpm.

August 5, 1988 at 1135: Results from an 0805 condenser off-gas sample calculated the primary to secondary leak rate at 0.06 gpm. This increase was attributed to an increase in the off-gas flow rate since there had been no increase in the stack gas radiation monitor RIA-2326 [VL;RI].

August 6, 1988 at 0000 to August 7, 1988 at 1800: Calculations of condenser off-gas samples indicated essentially no primary to secondary leakage even though the condenser off-gas radiation monitor RIA-0631 increased to as high as 481,432 cpm. An investigation of this anomaly disclosed that there was considerable air inleakage at the condenser off-gas sample

. point which was diluting the samples and leading to a low estimate of the primary to secondary leakage.

Cause Of The Event Initial investigation of the primary to secondary leakage revealed some leakage from several mechanically plugged steam generator tubes in the "B" steam generator hot leg. Eddy current testing is in progress. A supplemental report will be submitted that discusses the results of the eddy current testing, the cause of the failure and all planned corrective actions.

Analysis Of The Event This report. is being made for information purposes. Our subsequent investigation of the primary to secondary leak rate determined that the Plant did not exceed Technical Specification 3.1.5.d time limit of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with leakage greater than 0.30 gpm.

The investigation based its findings on valid leak rate calculation of 0.31 gpm and 0.33 gpm and the corresponding readings from the condenser off-gas radiation monitor RIA-0631. This calculation showed that a leak rate of 0.30 gpm corresponded to an RIA-0631 count rate of approximately 450,000 cpm. A review of RIA-0631 data determined a leak rate exceeding 0.30 gpm occurred from 1815 on August 7 to 1238 on August 8. Because the Technical Specification limit was not exceeded, it is concluded that no safety consequences resulted from this event. In addition, steam generator tube leaks are bounded by the analysis for steam generator tube rupture which is an analyzed accident.

N .. C FO .. ~ 388A 19-a31 LER 88012-LIOl

NRC Form JllA U.S. NUCLEAR REGULATORY COMMISSION 19-831 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVED OMS NO. 3150-0Ta.

EXPIRES: 8/31 /85 FACILITY NAME 111 DOCKET NUMHR (21 LEll NUM8ER 1111 PAGE (31 YEA,_

PALISADES NUCLEAR PLANT osooo2 558 8-o i2 0 0 4 OF 0 4 TEXT ! I f - - II ,.,,.,;r.J. - Mlt/lliotwl NltC Fomt ~*111171 Corrective Action Technical Specification 4.14~2.6 requires a six percent eddy current sample of unplugged tubes in the affected leg. Eddy current testing is currently in progress. Specific corrective actions will be determined based on the results of the tests.

Regarding the air inleakage problems at the condenser off-gas sample point, Plant Chemistry is evaluating possible modifications to the sample point to verify system integrity to ensure representative samples. In addition, possible alternate backup methods for determining primary to secondary leakage are being evaluated.

Additional Information A similar event occurred in 1982 and is addressed in Licensee Event Report 82-012.

N .. C FO .. M 388A 1H3 i LER 88012-LIOl

consumers Power POWERINli MICHlliAN'S PROliRESS General Offices: 1945 West Parnall Road, Jackson, Ml 49201 * (517) 788-0550 September 6, 1988 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -

LICENSEE EVENT REPORT 88-012 - STEAM GENERATOR TUBE LEAKAGE Licensee Event Report (LER)88-012, (Steam Generator Tube Leakage) is attached. This event is being reported to the NRC as an informational LER.

Brian D Johnson Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades Attachment OC0988-0ll 7-NL02

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