ML20199F270
| ML20199F270 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 01/22/1998 |
| From: | Alexion T NRC (Affiliation Not Assigned) |
| To: | NRC (Affiliation Not Assigned) |
| References | |
| TAC-M98968, TAC-M98969, NUDOCS 9802030115 | |
| Download: ML20199F270 (1) | |
Text
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UNITED STATES i
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NUCLEAR REGULATORY COMMISSION WASHINGTON D.C. 20066-0001 s***+,$;
January 22, 1998 NOTE TO: PD IV 1 File -
'FROM kom Alexion -
Project Dwoctorate IV-1 Division of Reactor Projects lil/IV Office of Nuclear Reactor Regulation
SUBJECT:
LICENSEE'S 10 CFR 50.59 FVALUATION OF THlMBLE GUIDE TUBE NUT REPLACEMENT, SOUTH TEXAS PROJECT, UNITS 1 AND 2 (TAC NOS. M98968 AND M96969)
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By letter dated December 17,1996, the licensee provided its 10 CFR 50.59 Summary Report.
Based on my review of the Summary Report, Unroviewed Safety Question Evaluation (USQE) 96-0027, titled, " Replace Original Compression Nuts in the BMI [ Bottom Mounted Instrument].
Thimble Guide Tubes with an Altemate Split Nut Design," was selected for further review by the j
Office of Nuclear Reactor Regulation (NRR) technical staff. The reviewer was G. Homseth Materials and Chemical Engineering Branch, Division of Engineenng.
This USQE supports replacing damaged original compression nuts in the incore neutron flux -
monitoring system Mttom mounted instrument thimble guide tubes with an attemate split nut design. During the *
- refueling outage on Unit 1, several of the compression nuts were found ga; led and could not. repaired.-
f The staff has reviewed the licensee's 10 CFR 50.59 documentation for the thimble guide tube nut.
replacement and finds the licensee's design and design evaluation to be acceF4&MG. The licensee selecte1 appre 'ste materials for the redesigned nut (incorporating a split nut and fasteners). The ASTM A479 grade 316 or 316L stainless steel specified for the' split nut material is comparable to the original installation and is comparable with the intended service. The -
rW ASTM F837, group 1l condition CW austenitic stainless steel socket head cap screws usad in the modified design are also appropriate for the intended service.
Docket Nos. 50 498 and 50-499
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Attachment:
As stated h
D6STRIBUTION:
Docket File PUBLIC (PDR)
PDIV-1 r/f :
JTapia TAlexion HC TM DENTSBCDPV 9802030115 980122
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PDR ADOCK 0500~198 P
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