05000289/LER-1984-007, Corrected LER 84-007-01:on 841116,once-through Steam Generator a Tubes Identified as Category C-3 Defective (More than 1% of Insp Tubes Defective).Further Manifestation of Problem Found During 1981 & 1982 Testing
| ML20126F897 | |
| Person / Time | |
|---|---|
| Site: | Three Mile Island  |
| Issue date: | 05/31/1985 |
| From: | Hukill H, Otto S GENERAL PUBLIC UTILITIES CORP. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20126F876 | List: |
| References | |
| 5211-85-2064, LER-84-007-01, LER-84-7-1, NUDOCS 8506170663 | |
| Download: ML20126F897 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| 2892084007R00 - NRC Website | |
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THREE MILE ISLAND, UNIT 1 oIeioIoIo12 8;9 i jopl 0 ;5 TITLE tel DEFECTIVE OTSG TUBES l EVENT DATE 15 LER NURSER tt) R$PO8IT DATE 171 OTHER F ACILITIES INvoLytD les MONTH DAY vtAR v4AR ". M n'" ",' M MONT*4 Day vtAR '*C' Levy asaues DOCuty Nuvetm<si o 15 t o l o l o l I i 1l1 1l6 84 8 l4 0l0 l 7 0l1 0l 5 3 l1 8l5 o isio io i o , i i l
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S 20.40SisH1Het se.734sH2Hius to.73?aH2Hal uCENSEE CONTACT POR TM80 LER H3) 41mg TELEP ONE NvHSER j Susan Otto, TMI-1 Licensing Engineer 711 17 9 I4 I 8I- 18131515 cOesPLaTa ONa uNa POR sAcw cOesPONaNT PAsLums DescReso iN TMie REPORT nn !
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On November 16, 1984, tubes in 0TSG A were identified during Eddy Current Testing (ECT) as being defective. The inspection results in the periphery of OTSG A were declared to be in category C-3 (more than 1% of inspected tubes are defective) per T.S. 4.19. ECT continued in both 0TSG A and B to identify the full extent of the indications..
The root cause of this event is discussed in TOR-666, " Adequacy of TMI-1 OTSG Return to Service Safety Assessment After 1984 Technical Specification ECT l Examination," which concludes the most probable and reasonable explanation for the new indications during the 1984 examination is the enhanced visibility of !
pre-existing indications on the threshold of detectability. TDR-666 concludes that the corrosion failure mechanism identified in 1983 is still the correct description of what the OTSGs have undergone. The precautions taken to prevent reoccurrence have been adequately observed and are effective; no new material attack has occurred.
Defective tubes were removed from service in accordance with T.S. 4.19.4.a.6. The results of the eddy current inspection have been evaluated and reported to the NRC in TDR-652, " Evaluation of the 1984 Required Technical Specification Examination of the TMI-1 OTSG."
In accordance with 10 CFR 50.59, GPUN has performed a safety evaluation to ensure that plugging up to 2000 tubes with up to 75% of plugged tubes in 0TSG A would have no adverse affect on performance of the steam generators and would not involve an "Unreviewed Safety Question." l 8506170663 850606 ;
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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION areaovao ous ao siso-oio.
ExPtRES 8/3145 FACILITV Naast (13 OOCKET NUedBER (28 ggn quuggn (g) Paos (33 THREE MILE ISLAND, UNIT 1
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. < ~ ~nc- meenm I. PLANT OPERATING CONDITIONS BEFORE THE EVENT !
TMI-1 was in a cold shutdown condition with the Once Through Steam Generator (OTSG) upper manways removed for access to conduct routine technical specification surveillance testing of OTSG tubes. Reactor Cooling System cold leg piping (including the OTSG's) was drained.
II. STATUS OF STRUCTURES / COMPONENTS Prior to Eddy Current Testing (ECT), both OTSG A and B were considered operable (no leakage observed during the October 1984 bubble and drip tests). Routine ECT was being conducted per Technical Specification 4.19 requirements.
During 1981, TMI-l's 0TSG A and B tubes experienced intergranular stress assisted cracking (IGSAC) originating in the tube primary side, which is the inside diameter of the tube. The IGSAC was in the tubes primarily in the upper tubesheet region. As discussed in GPUN Topical Report #008, both OTSG A and B tubes have been repaired by: 1) a kinetic expansion process in the upper tubesheets, 2) and removing some tubes from service. At present OTSG A has 1217 tubes removed from service and the OTSG B has 325 tubes removed from service. There are 15,531 tubes in each OTSG.
III. EVENT DESCRIPTION On 11/16/84 tubes in OTSG A were identified by ECT as being defective
(>_40% through wall). The inspection results in the periphery of 0TSG A were declared to be in category C-3 (more than 1% of the inspected tubes are defective) per T.S. 4.19 at 1715 hours0.0198 days <br />0.476 hours <br />0.00284 weeks <br />6.525575e-4 months <br /> on 11/16/84, and the NRC was notified by phone. In OTSG B less than 1% of the tubes in the first 3% inspection sample were identified by ECT as being defective.
.O AM 308A
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION A>Paovf o ous =o siso-oiu EXPIRES S/31/88 FACILITY esAmet m DOCKET NueeBER 125 LEA h m ERIS) PAGE13)
THREE MILE ISLAND, UNIT 1 o l510 lo 1012 l 819 814 -
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Further ECT continued in both OTSG A and B to identify the full extent of these indications. ECT was completed in December, 1984.
Most of the ECT indications were in peripheral tubes, on the primary side (which is the inside diameter of the tubes), of limited circumferential extent, and were not through wall. Generally, the ECT indications were predominantly found in the 46 inch free span between the bottom face of the upper tubesheet and the 15th tube support plate.
By letter 5211-85-2010 dated January 14, 1985, GPUN transmitted TDR-638
" Evaluation of Eddy Current Indications Detected During the 1984 Tech.
Spec Inspection." Subsequently, by letter 5211-85-2073 dated April 11, 1985 GPUN submitted our final report, TDR-666, " Adequacy of TMI-1 OTSG Return to Service Safety Assessment After 1984 Technical Specification ECT Examination," which reiterates the TDR-638 conclusion that the most probable and reasonable explanation for the new indications during the 1984 examination is the enhanced visibility of pre-existing indications on the threshold of detectability. TDR-666 concludes that the corrosion failure mechanism identified in 1983 is still the correct description of what the OTSGs have undergone. The precautions taken to prevent reoccurrence have been adequately observed and are effective; no new material attack has occurred.
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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION AerRovEo ove No. mo-om EMPIRES 8/3145 F ACIUTV NAME til DOCKET NUMBER (21 gga gyugga (g3 pagg(3 THREE MILE ISLAND, UNIT 1 "'" "20E" '
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011 014 0F 0B rur - . - mm4,,nn IV. CCMP0NENT FAILURE DATA Component Name: Once Through Steam Generator Component System: Reactor Coolant System Component Manufacturer: Babcock and Wilcox Reportable to NPRDS: Y Method of Discovery: Eddy Current Testing V. AUTOMATIC OR MANUALLY INITIATED SAFETY SYSTEM RESPONSE Not applicable to this event.
VI. ASSESSMENT OF THE SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT TMI-1 was in a cold shutdown condition. Tube leakage tests completed in October, 1984, several weeks prior to this event, indicated no detectable tube leakage. Therefore, no safety consequences have occurred.
VII. PREVIOUS EVENTS OF A SIMILAR NATURE As stated in Section II, IGSA cracking in OTSG tubes at THI-1 had previously been detected in Eddy Current tests conducted in 1981 and 1982 which required tubes to be repaired or removed from service.
VIII. CORRECTIVE ACTIONS PLANNED Defective tubes were removed from service in accordance with the Technical Specification 4.19.4.a.6, as summarized in GPUN letter 5211-85-2071 dated April 18, 1985. The results of the eddy current inspection have been evaluated and reported to NRC in TDR-652,
" Evaluation of the 1984 Required Technical Specification Examination of the TMI-1 OTSG," submitted by GPUN letter 5211-85-2073. As discussed with F. Young of NRC on April 10, 1985, this satisfies the T.S. 4.19.5 requirements for reporting results of OTSG inservice inspections.
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asRC Form 336A U S. NUCLEA2 K EIULAToRY CoastestsioN
"* LICENSEE EVENT REPORT (LER) TEXT CONTINUATION AreaovEo out No aiso-oio.
ExpenES 8/3i/85 F AciLITV NAASE in DOCKET NutASER (2) LER NuneSER ISI PAGE (31
"'" " E" '#'U THREE MILE ISLAND, UNIT 1 olslolojol2l8l9 8j 4 -
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0 l1 0l5 os 0l5 Text ,- ., N.C w mi.w nn TR-008, Rev. 3 " Assessment of TMI-1 Plant Safety for Return to Service After Steam Generator Repair," described the results of analyses performed to determine if the steam generators could be operated safely with up to 1500 tubes removed from service. In accordance with 10 CFR 50.59, GPUN has performed a safety evaluation to ensure that plugging of up to 2000 tubes with up to 75% of the plugged tubes in OTSG A would have no adverse effect on performance of the steam generators. Our evaluation has established that this modification does not involve an "Unreviewed Safety Question" as defined in 10 CFR 50.59.
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GPU Nuclear Corporation Nuclear o
- ems =$o Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
May 31,1985 5211-85-2064 Office of Nuclear Reactor Regulation Attn: J. F. Stolz, Chief Operating Reactor Branch No. 4 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Stolz:
Three Mile Island Nuclear Station Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 LER 84-007-01 This letter transmits Licensee Event Report (LER) No. LER 84-007-01. LER 84-007-00 submitted December 17, 1984 dealt with defective Once Through Steam Generator Tubes. As corrective action, defective tubes have been removed from service by plugging. LER 84-007-01 summarizes information previously submitted, including our assessment of the root cause of the event. Public health and safety were unaffected.
This LER is being submitted pursuant to 10 CFR 50.73, using the required NRC forms (attached). NRC form 366 contains an abstract which provides a brief description of the event. For a complete understanding of the event, refer to the text of the report which appears on Form 366A.
Sincerely, H. D. 11 Director, TMI-1 SK: dis:1835f Attachment l
GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
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