ML19256D680
| ML19256D680 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 09/08/1977 |
| From: | Stello V Office of Nuclear Reactor Regulation |
| To: | Thornburg H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| NUDOCS 7910220600 | |
| Download: ML19256D680 (3) | |
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j MEMORANDUM FOR: Harold D. Thornburg Director, Division of Reactor Operations Inspection FROM:
Victor Stello, Jr. Director, Division of Operating Reactors
SUBJECT:
THREE MILE ISLAND UNIT NO.1. DECAY HEAT REMOVAL
. PUMPS By letter dated September 1,1977 to Metropolitar. Edison Company (Fot Ed), you outlined an agreement between your office and Met Ed wherein disassembly and liquid penetrant examination of the decay heat removal
.,' pumps at Thme Mile Island Unit No.1 (TMI-1) would be initiated by
. ; 8:00 a.m.,' September 9,1977 ur.less deferred in writing by your
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A / office based on a safety analysis submittsd by Met Ed.
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By. letter dated September 6,1977 Het Ed submitted a safety analysis 8
presenting reasons why such an inspection could be deferred ur.til a
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. later date. Incicded in this safety analysis were conclusions drawn from the results of vibration measurements and ultrasonic examinations performed on both of the TMI-1 pumps on the weekend of September 3 and e
- 4. 1977. These measurements indicated that the pump shafts wem free of defects and t'% continuities and that vibration levels were well within the acceptance criteria of the Hydraulic Institute Standard.
On September 7,1977, members of the NRC staff met with representatives of Met Ed, Babcock & Wilcox, and their consultants to obtain further brekground information relating to the safety analysis.
Included in the infomation obtained at this meeting was the fact that the earlier failure of a similar pump shaft at Crystal River Unit No. 3 was in the form of a basically transverse (cup and cone) crack and the opinion expressed by tre staff that ultrasonic examination could detect early phases of cracks with this orientation. It was also noted that vibration measurements could be of value in detecting j
pump mechanical degradation.'
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m As a result of the meeting. the staff concluded that the liquid penetrant examination could be deferred temporarily on the condition that Het Ed promptly supplied a written comitment relative to the following:
1.
To perfom vibration measurements and ultrasonic examiration of the Decay Heat pu m shafts monthly. To perfom the vibration measurements at a flow rate of 600 gpm. To provide an icmediate report to OI&E of any UT inc'ications or a 50% increase in vibration emplitude at any frequency.
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To provide the results of the vibration and UT measurements perfomed on these pumps on the weekend of September 3 and 4,1977.
Io propose corrective action to be followed in the event defects are detected or the vibration limits is exceeded.
- 2.
To provide the results of a metallurgical and fracture
. examination of the shaft which failed at Crystal River Unit No. 3 (preliminary results due 9/14/77; final report due9/28/77).
3.
To provide a summary of the metallumical properties of the
? TMI-1 and failed Crystal River Unit No. 3 pump shafts.
(Preliminary report due 9/2T/77; final report due 10/5/77).
v 4r To provide a discussion of the suitability of the pump design, including recirculation flow, for the present TMI-1 application 7
(due10/5/77).
5.
To provide copies of letters from Worthington (stating the
-expected prap life at 80 g;::a) and from Babcock & Wilbox (stating the required punp life at 80 grm{ by September 8,1977.
Met Ed agreed at this meeting to provide a written comitment to the above items. Accordingly, subject to receipt of this written comit-ment and the specified information, we conclude that deferral of the liquid penetrant examination to a future date is acceptable.
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3-The future date at which liquid penetrant examination should be perfonned will be determined following our review of the infomation to be subciitted by Met Ed.
Victor Ste110. Jr., Director Division of Operating Reactors Office of Nuclear Reactor Regulation 4.
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