ML20127G475
| ML20127G475 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 03/19/1973 |
| From: | Mayer L NORTHERN STATES POWER CO. |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9211160615 | |
| Download: ML20127G475 (1) | |
Text
.rm me-x NSED NORTHERN STATES POWER COMPANY l
Minneapolis, Minnesota 55401 g y(-
i\\d March 19,1973 V
N
.c m
~
o
,9{ '. y. \\', I I
/*
N.g'j3 ' Q
,' gjS
'I Mr. A. Gi ambusso I
Deputy Director for Reactor Projects i.
/.
United States Atomic Energy Conrnission
\\
Washington, D C 20545 e,7 7 p
Dear Mr. Giambusso:
LOtBICELLO f1CLE AR GEfERATifG PLAfD Docket No. 50-263 License No. IPR-22 Main Steam Tunnel High Area Temperature Switch Set Point Deviation A condition occurred at the Monticello Nuclear Generating Plant recently which we are reporting to your office in accordance wi th Section 6.6.C.1 of Appendix A, Technical Specifications, of Provisional Operating License DPR-22. On Tuesday, March 6,1973, while performing a refueling outage surveillance test, the trip setpoint of one of the sixteen " Main Steam Tunnel Hich Agea Temperature-Group I isolation" temperature switches was found to be 204 I; 4 F above the Technical Speci fication limi t.
The switch trip setting was readjusted.
Subse-quent bench testing denonstrated repeatable performance at the desired trip setting.
The tenperature switch was re-installed and functionally tested with satisfactory resul ts.
The sixteen tenperature switches are connected in a "one of two twice" logic schene at four locations in the steam tunnel.
Redundant tenperaturo switches at the sane location would have provided the desired trip action at the desired trip setting, had a steam line break occurred during reactor operation.
Yours very truly, gd.
n>
L 0 Mayer, PE c) poemtn 4
Director of Nuclear Support Services 9AEC fE MAR 231973 " 3 LOWkik i
REGULATORY cc:
Boyce Grier WAIL MCTION G Charnoff DOCET CLERK 6
Minnesota Pollution Control Agency, ATTN:
Ken Dzugan a
oo 9211160615 730319 t