ML20090E175
| ML20090E175 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 06/03/1974 |
| From: | Schneider R NIAGARA MOHAWK POWER CORP. |
| To: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 5217, AO-50-220-74-8, NUDOCS 8303140025 | |
| Download: ML20090E175 (3) | |
Text
.
n) r y.
NIAGARA MOHAWK POWER CORPORATION NI AGAH A MOHAWK g
/
soo omt noutavAno wtst nr I
s synacusc.n.v sazoa c
9]
JUN111974- -2 L8. nc:n: tamy CDMMtt,t c,
gyg f
a June 3, 1974 S0-220 g
Mr. D'onald J. Skovholt Assistant Director for Reactor Operations Division of Reactor Licensing United States Atomic Energy Commission Washington, D.C.
20545
Dear. Mr. Skovnolt:
In accordance with Technical Spec,ifications for Nine Mile Point Unit 1, 1.13d, the enclosed Abnormal Occurrence Report is submitted.
This report is in accordance with the format set forth in Regulatory Guideline 1.16.
Very truly yours, Original Signed by R.R. Schneider R.R. Schneider Vice' President - Electric Operations RRS/bar.
O sgo 830314 5 740603
~
).
q q
S w
g 5217.
cory sexr armeg
/
~'
-O r.
- s o
o V
ABNORMAL ~ OCCURRENCE REPORT 1.
-Report No.
50-220/74-8 2a.
Date June 3, 19.74 2b.
Occurrence Date May 31, 1974 3.
Facility Nine Mile Point Nucicar Station Unit 1-4.
Ident'ificaticn of Occurrence Setpoint drift on Drywell High Pressure 5.
Conditions ~ Prior to Occurrence Unit I was shutdown for annual' refueling
-6.
Description of Occurrence During routine surveillance testing on May 31, 1974 at'approximately 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br />, two Barton Instruments used= in the Drywell High Pressure.
(3.5 psig) RPS were found-to ~have drifted. 20 psi higher' than required.
The surveillance -test consists of operating the ! switch thru regulated (mercury tanometer) air signal to the. sensor. The two Barton Instruments-Model 289,-E.P. #RE04AGD are in; separate RPS trip. systems.
With reactor in. refuel mode and the.drywell under -atmospheric conditionse no operator action was necessary, as the. plant was in a safe condition.
7.
Designation of Apparent Cause of-the-Occurrence-Setpoint drift 8.
Analysis 'of Occurrence The high drywel1~ pressure trip requires a~one out.of two ;twice logic.~
to actuate _ the protective function. One1 channel'inf eachltrip sy' stem
)
would have actuated'at the required setpoint and thus' produced-the?.
- protective 5 function. Therefore, no hazard would have 'been1 presented c -
to the general public. or: station hadJthe protective function been"
' required.
-9.
Corrective Actioni m-j;,
i E
The-immediate' corrective-action involved recalibration of the-Barton-ication haslbeen made to the Barton switch,.% +.053 psig. lA modif--
switch. The normal valveJof-setpoint is: 3
.' A new; switch plate 11ocking device to prevent setpoint ' drift' has ' been~ insta11e'd h '(AOR '74-1). ;This
~ modificationfshould reduceJsetpoint drift-problems.withithis switch.
~
g T _
~
.a i
+
+
s
~
s
'f an-1 lJ
^
U"
'i Z y
[Shh M
jj k
- o.
~
O June 3,1974 ~
yAbnormal0ccurrence; Report el
+
~
1
'10.
- Failure Data i'
No~ previous setpoint drifting has occurred on these switches this year. -AOR 74-1.concerning a Barton switch setpoint drift is the only,
}
other drift in setpoint to date in 1974.
ej 1
1 y
t e
i<'
+
4 r
f t
e J.
k 9
9 4
9 y.
b
' 4 3
i+ ' ' f^
a?.
E a
r
~ l f
2
+
',"a.
J-e s
t L_^'
Am
-