ML20064L245
| ML20064L245 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Crane |
| Issue date: | 04/08/1982 |
| From: | Vollmer R Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML082180535 | List:
|
| References | |
| CON-FIN-B-2506-2, FOIA-82-261 20-82-283, NUDOCS 8204200442 | |
| Download: ML20064L245 (1) | |
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APR 0 81982 STANDARD ORDER FOR DOE WORK ISSUE D TO: IDOL Of fice)
ISSUI O BY: INRC Of ficel ACCOUNTING CIT ATION AP8'RO5'H 4 AT OON $Y MtsOt.
Richland Operations Office Office of Nuclear Reactor 31X0200.202 Regulation, DE se.a nount,4 20-19-10-11-2 PERF OIMING ORG ANIZ ATION AND LOC ATION Battelle Pacific Northwest Laboratory e iN uuuno H
.Richland, WA B2506-2 WOR K PEHIOD - THIS ORDE R FIN TITLE FIXED D ESTIMATED LN Evaluation of Three Mile Island, Unit No. 1 Steam Generator FHOM.
TO:
Corrosion 1/25/82 5/31/82 OBLIGATION AVAILABILITY PROVIDED BY:
5 0 A. THIS ORDER 21, TOTAL OF OHDERS PL ACED PRIOR 10 lHIS DAT E WITH THE PERF OHMING ORG ANIZATION
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3,396,000 E
C. TOTAL ORDERS TO DATE (TOT AL A & B) 5 3,396,000 D. AMOUNT INCLUDED IN "C" APPLICABLE TO THE " FIN NUMBER" CITED IN THIS ORDER.
$ 20,000 FINANCIAL FLEXIBILITY:
D TUNDS WILL NOT BE REPROGRAMMED BETWEEN FINS. LINE D CONSTITUTES A LIMITATION ON OBLIGATIONS AU T HORIZ E D.
8 FUNDS MAY BE REPROGRAMMEDNO TO E XCE ED 10% OF FIN LEVEL UP TO S50K. LINE C CONSTITUTES A LIMIT ATION ON OHLIGATIONS AUTHORIZED 1 SEE BELOW STANDARD TERMS AND CONDITIONS PROVIDED DOE ARE CONSIDERED PART OF THIS ORDER UNLESS OTHERWISE NOTED, AT T ACH ME NTS.
THE FOLLOWING ATTACHMENTS ARE HEREDY SECURITY:
MADE A PART OF THIS ORDER:
O WORK ON THIS ORDER IS NOT CLASSIFIED.
O STATEMENT OF WORK O WORK ON THIS ORDER INVOLVES CLASSlFIED INFORMATION. NRC FORM 187 IS ATTACHED.
O ADDITIONAL TERMS AND CONDITIONS O OTHER REMA2KS:
This order approves Dr. Digby Mcdonald as a subcontractor to PNL on this work and changes the period of performance at no additional cost to the NRC.
After acceptance, please send to the NRC Office of the Controller ATTN: D. Dandois, and provide a copy-to the Office of Nuclear Reactor ReculatiOn. AYTN D. Corlev.
JSsUING AUTHORITY ACCEPTING ORGANIZATION Nr kl Richa d H r
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)ivision of Engineering, NRR
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NHC FORM 173 (?-78) 1/ Reprogramming 1imited to
<hanges on FINS siithin the same B&
fnd the same Appropriation Symbol.R Number In order for this reallocation to b effective, this
}ounter-signed to completffice must be notified within 5 days so that an appropr the action prior to receipt of any bills.
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UNITED STATES e
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7, NUCLEAR REGULATORY COMMISSION
)"E WASHINGTON. D. C. 20665 APRIL 't 81982 Docket No. 50-289 FACILITY: Three Mile Island, Unit No.1 (TMI-1)
LICENSEE: GPU Nuclear Corporation (GPU)
SUBJECT:
SUMMARY
OF MEETING WITH GPU ON APRIL 7,1982 CONCERNING STEAM GENERATOR TUBE PROBLEMS ON TMI-l
Background
In late November 1981, while the plant was in a cold shutdown condition, primary to secondary leakage was detected in the Once Through Steam Generators (OTSGs). GPU's investigation of this problem has revealed that there are 8-10,000 tubes with defects as detennined by eddy current testing (ECT).
GPU has conducted a comprehensive program in the areas of ECT, tube failure analysis, and tube repair techniques. The purpose of this meeting was to update the staff on the results of GPU's program since the last meeting on January 25, 1982 and to brief the staff on the proposed repair technique. Copies of GPU's presentation and a list of attendees are enclosed.
Discussion GPU has completed the majority of the effort related to detennining the extent and cause of the tube failures. The extent of the attack within the OTSGs has been almost entirely limited to the top 2-3 inches of the tubes within the 24 inch tubesheet near the roll transition area. Only about 2% of the total defects fall below the 3 inch level as measured from the top face of the upper tubesheet (UTS). 1he majority of the defects are located near the outer periphery of the tube bundle although there is an assymmetry in the defect locations between the "A" and "B" OTSGs in the radial direction which cannot presently be explained.
With regard to the failure mechanism, GPU's failure analysis effort con-cluded that the "right" conditions of sensitized material subjected to relatively high stress (residual plus operational) and exposed to an aggressive chemical environment were needed to car e the corrosion. The failures were caused by stress assisted intergrant..ar corrosion initiated from the ID surface resulting in circunferential intergranular cracks. The aggressive chemical species was sulfur in a reduced form although carbon and chloride were also present as contaminants on the tube surfaces.
GPU's failure analysis effort has been a very comprehensive program involving: 1) an extensive metallographic and chemical laboratory analysis of portions of 19 removed tubes; 2) an OTSG fabrication history review including heat treatments and stress history; 3) an operational history review of the past 3 years to determine how sulfur entered the Reactor Coolant System (RCS) and other operational indicators which may have con-tributed to the problem; and 4) review of industry experience with inter-granular stress corrosion cracking of Inconel 600. Other important con-Alg6 o y pt, 7 poAL/4
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clusions from the failure analysis effort indicate that: 1)theeddy current examination is a reliable indicator of crack location; 2) uncracked tubing still exceeds minimum tube specifications and 3) corrosion tests in actual primary coolant indicate that the coolant is currently innocuous.
GPU fomulated the following proposed failure scenario which is con-sistent with their investigation results. Sulfate and thiosulfate' were inadvertently added to the RCS during the shutdown period. Reduced sulfur species formed during hot functional testing in August and September 1981. Following plant cooldown when the RCS water level was lowered, a high concentration of aggressive sulfur species fomed in the dryout region and cracking occurred in this region. The cracking then teminated due to a reduction in concentration.
With respect to the steam generator repair method, GPU intends to expand the tubes below the present roll area in order to close the existing crevice area and then establic a new leak limiting / load carrying hard roll at the 8-10 inch level in the tubesheet. By this method, the vast majority of l
the defects would be above the new primary to secondary seal. Any tubes t
with defects below this rolled area would be plugged. This procedure has l
the benefits of allowing use of remotely operated tooling resulting in lower man rem exposure, allow continued NDE of repaired tubes, and pemit sleeve installation if that is later dett. mined to be necessary. Using this repair procedure, GPU perdicts that the repairs could be completed and the plant ready for operation by October.1982 Prio:- to commencing repains, a comprehensive qualificat on program will be undertaken. Since the repair method involves mechanichl joints, some amount of primary to secondary leakage is possible, but leakage must remain within the Appendix I and other Technical Specification limits.. Even if it is assumed that large numbers of tubes fail within the UTS, the cumulative failure would remain within the design basis tube rupture accident envelope.
GPU intends to perform a complete internal review under the provisions of l
10 CFR 50.59 and will have the internal safety review reassessed by GPU's General Office Review Board (G0RB) as well as an external independent review group.
With rer,ect to the potential that the corrosion attack may have affected other RCS materials, GPU outlined their intended inspection program. To l
date, they have classified all RCS materials as to their corrosion sus-l ceptibility and have developed an inspection plan which calls for use of various NDE techniques as well as some destructive laboratory testing.
I ISulfuric acid, which provides sulfate, may trave entered the RCS during an event in 1979. Thiosulfate entered the RCS from valve leakage from the sodium thiosulfate tank associated with the Reactor Building Spray System and then subsequent system cross connection.
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The inspection of the reactor vessel internals is scheduled to begin this week.
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Richard H. Jac s Project Manager Operating Rea t s Branch #4 Division of Licensing
Enclosures:
1.
List of Attendees 2.
GPU Presentation cc w/ enclosures:
See next page
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ORBf4:DL MEETING SUPfMRY DISTRIBUTION Licensee:
GPU Nuclear Corporation
- Copies also sent to those people on service (cc) list for subject plant (s).
Docket File NRC PDR L PDR ORB #4 Rdg TNovak JStolz Project ihnager-RJacobs 1
Licensing Assistant-RIngram OELD Heltemes, AE0D IE-3 SShowe (PUR)
Meeting Sumnary File-0RBf4 RFraley, ACRS-10 Program Support Branch ORAB, Rm. 542 BGrimes, DEP SSchwartz, DEP SRamos, EPDB FPagano, EPLB FCombs H0rnstein KWichman EBrown
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RVollmer Abates WJohnston Bli.aw CMcCracken JGray PMatthews JCutchin EIgne PWu PGrant WCollins CSellers EMurphy l
DHaverkamp FYoung I
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LIST OF ATTENDEES - MEETING WITH GPU NUCLEAR APRIL 7,1982 STEAM GENERATOR TUBE PROBLEMS AT TMI-1 NRC GPU NRC Consultants D. Eisenhut P. Clark C. Dodd, ORNL R. Vollmer*
H. Hukill R. Dillon, PNL T. Novak R. Wilson D. MacDonald, Ohio State W. Jo'inston R. Long u
J. Stolz D. Slear C. McCracken E. Wallace GPU Consultants R. Jacobs J. Colitz P. Matthews M. Graham J. Pearson, B&W E. Igne D. Cowfer R. Kosciba, B&W H. Ornstein R. Barley S. Weems, MPR E. Brown S. Giacobbe R. Jones, EPRI A. Bates F. Trowbridge, Counsel B. Liaw T. Baxter, Counsel
'J. Gray J. Cutchin P. Wu W. Collins Other Attendees E. Murphy P. Grant W. Dornsife, Commonwealth of Pa.
C. Sellers S. Maingi, Commonwealth of Pa.
D. Haverkamp C. Gardner, GA0 F. Young D. Leighton, Leighton Ass., Inc.
.Part time P. Hinsburg, Inside NRC L. Connor, Doc. Search, Ass.
J. Reisland EPRI R. Borsum, B&W
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