ML17037B648
| ML17037B648 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 12/29/1976 |
| From: | Rhode G Niagara Mohawk Power Corp |
| To: | Lear G Office of Nuclear Reactor Regulation |
| References | |
| Download: ML17037B648 (6) | |
Text
U.S. NUCLEAR REGULATORYCOM'ON l
NRC FORM 195 I2 7B) h1RC DISTRIBUTION FoR PART 50 DOCKET NIATERIAL DOCKET NUMBER
$0-z zo FILE NUMBER Mr. Lear
@LETTE R
~O R IG INAI OCOPV I-INOTOR IZED
@UNCLASSIFIED PROP Niagara Mohawk Power Corp.
Syracuse N.Y.
13202 Geral< K. Rhode INPUT FORM DATE OF DOCUMENT 12-29-76 DATE RECEIVED 1-4-77 NUMBER OF COPIES RECEIVED 1 signe org.
DESCRIPTION Ltr. Ref 5<<11-76 ltr, Furnishing A, information on the Fee water Nozzle Inspection program to be starte< in the Spring of 1977...
( 2 pages
)
ENCLOSURE j
IACKNOWLEDGED 90 NOT REMOVE PLANT NAME: NINE MIZg PrP UNIrP P SAFETY ASSIGNED AD:
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Hegnlatory Docket File NIAGARA MOHAWK POWER CORPORATION DOCKETED USNRC NIAGARA~
MOHAWK
- ABa, 300 ERIE BOULEVARDWEST SYRACUSE, N, Y. I3202 U.S. NUCIEAR REGULA ORY COMMISS ION Moll Soct Ion December 29, 1976 Q)
I5T Dire Nuclear Re'actor Regulation Attn:
Hr. George Lear, Chz,ef Operating Reactors Branch III3 U. S. Nuclear Regulatory Commi'ssion Vashington, D. C.
20555 HF
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I Re:
Nine Bile Point Unit 1 Docket No. 50-220 DPR-63
Dear 14z. Lear:
As discussed in our May ll, 1976 letter, a feedwater nozzle inspection is planned during the Spring 1977 refueling at'ine Bile Point Unit 1.
This letter provides additional information concerning the inspection program.
Plans and tooling development are in progress to effect removal of feedwater nozzle defects, cladding and a thin layer of base material should this become necessary, during this Spring 1977 outage.
Criteria and supporting analysis for removal of defects, cladding and a thin layer of base material, as such removal affects reinforcement requirements, are being developed.
Ultrasonic examinations of the nozzle blend radii, bores and safe ends will be performed to establish a baseline for future verification of nozzle integrity.
Additionally, dye penetrant in-spections will be performed on all feedwater nozzles.
If feedwater spargers need replacement, they will be replaced with spargezs of an improved design, which combines conservative features of the existing spargers with improvements to reduce ther-mal cycling at the nozzles.
The replacement design will have a
rectangular cross section with its attendant low velocity and resistance to vibration.
The new spargers will be made of carbon steel.
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2 Each sparger will incorporate a piston ring seal section on the thermal sleeve to minimize bypass leakage.
A moderate inter-ference fit between the thermal sleeve and the nozzle will also be used.
Flow shrouds will be used to. prevent the mixing of reactor water with colder feedwater in the nozzle-thermal sleeve annulus and blend radius.
A controlled leakage path via flow holes in the shrouds will be provided.
The improved design has been discussed w1th the Nuclear Regulatory Commission staff on September 7i 1976.
Prior to implementation, this program will be reviewed by the Site Operations Review Committee and the Safety Review and Audit Board.
In any case, t'e criteria for removal of defects, cladding and base materi'al on the feedwater nozzles wall be submitted to you by March 1, 1977
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A final report of t'e results of the inspection will be provided for information after completion of this outage.
Si ncerel y,
'I NIAGARA MOHAWK POWER CORPORATION GERA K. RHODE Vice Preside t
-. Engineering MGM/sz
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