Part 21 Report - 1997-591
ACCESSION #: 9709050020
Illinois Power Company
Clinton Power Station
PO Box 678
Clinton IL 61727
ILLINOIS Tel 217 935-6220
POWER Fax 217 935-4632
An Illinova Company
Wayne D. Romberg
Assistant Vice President Nuclear
U-602823
4F.140
August 28, 1997
Docket No. 50-461 10CFR21.21
Document Control Desk
Nuclear Regulatory Commission
Washington, D. C. 20555
Subject: 10CFR21 Final Report 21-97-015: Improper Clearance for
Westinghouse Model 50DHP350 Circuit Breaker Arc Chute
Rear Arc Horn
Dear Madam or Sir:
On May 7, 1997, Illinois Power (IP) identified that five arc chutes,
manufacturer part number 567F417G02, for Westinghouse Model 50DHP350,
4160-volt circuit breakers, in stores were different in configuration
from the original arc chute and exhibited an inadequate clearance between
the rear arc horn and the arc chute molded case during installation.
Because of the inadequate clearance, excessive force would be required on
the line pole unit to allow the arc chute to attach to the front arc
chute support. When attempts were made to install one of the arc chutes
in the "A" Residual Heat Removal (RHR) system pump breaker, the line pole
unit of the circuit breaker deflected upwards. Attempts were made to
install the arc chute on all three phases of the breaker with the same
result. A suitable replacement for the RHR pump breaker arc chute was
located on an original spare breaker. Condition report 1-97-05-085 was
initiated to track investigation and resolution of this issue. This
issue was identified as potentially reportable under the provisions of
10CFR, Part 21.
IP notified the NRC via letter U-602779, dated July 2, 1997, that
the investigation of the arc chute rear arc horn issue was not completed
and additional time was needed to complete the investigation. IP has now
completed the evaluation of this condition under 10CFR21 and concludes
that this issue should be reported under the provisions of 10CFR21. The
basis for this conclusion is that installation of the arc chute could
cause the line pole unit to deflect, potentially causing the main and
arcing contacts to be out of adjustment and potentially affecting the
safety related function of the circuit breaker. The failure of the
breaker to operate properly could result in the loss of power to safety-
related equipment loads. The breaker's function is to supply Class 1E
power until a fault occurs (trip open) and shed loads, or close on demand
and supply Class 1E power to safety-related equipment.
U-602823
Page 2
IP is providing the following information in accordance with
10CFR21.21(c)(4). Initial notification of this matter will be provided
by facsimile of this letter to the NRC Operations Center in accordance
with 10CFR21.21(c)(3) within two days of the date the responsible officer
signs this letter.
(i) Wayne D. Romberg, Assistant Vice President of IP, Clinton
Power Station, Highway 54, 6 Miles East, Clinton, Illinois,
61727, is informing the Nuclear Regulatory Commission of a
condition reportable under the provisions of 10CFR, Part 21.
(ii) The basic component involved in this condition is the arc
chute, manufacturer part number 567F417G02, for Westinghouse
Model 50DHP350, 4160-volt circuit breakers.
(iii) The arc chute and rear arc horn were supplied to Clinton Power
Station by Westinghouse, Pittsburgh, PA.
(iv) The arc chute appears to be different in configuration from the
original arc chute and exhibited an inadequate clearance
between the rear arc horn and the arc chute molded case during
installation. Specifically, the replacement rear arc horn
contact currently in production for the breaker appears to be
different from the original rear arc horn contact installed in
the breaker. The major differences appear to be the position
and angle of bend for the contact. Because of the inadequate
clearance that occurs during installation, excessive force
would be required on the line pole unit to allow the arc chute
to attach to the front arc chute support. When attempts were
made to install one of the arc chutes in the "A" Residual Heat
Removal (RHR) system pump circuit breaker, the line pole unit
of the breaker deflected upward, indicating excessive tension
on the unit. Attempts were made to install the arc chute on
all three phases of the breaker with the same result.
IP has concluded that this issue should be reported under the
provisions of 10CFR21. The basis for this conclusion is that,
despite assurance from the supplier that the arc chute is the
correct part, IP is unable to determine if the rear arc horn
can be installed without adverse impact on the circuit breaker.
Installation of the arc chute could cause the line pole unit to
deflect, potentially causing the main and arcing contacts to be
out of adjustment and adversely affecting the safety-related
function of the circuit breaker. The impact of the additional
stress applied to the pole units is not known. However, the
failure of the breaker to operate properly could result in the
loss of power to safety-related equipment loads. The breaker's
function is to supply Class 1E power until a fault occurs (trip
open) and shed loads, or close on demand and supply Class 1E
power to safety-related equipment.
U-602823
Page 3
(v) The improper clearance condition was identified and determined
potentially reportable under the provisions of 10CFR21 on May
7, 1997. IP notified the NRC in a letter dated July 2, 1997,
that the investigation of the issue was not complete, and
additional time was needed for completion.
(vi) Clinton Power Station (CPS) has 5 of the potentially affected
arc chutes in stores. When attempts to install the deficient
arc chute were unsuccessful, a suitable replacement arc chute
was located on an original spare circuit breaker. None of the
deficient arc chutes have been installed in the plant. IP is
not aware of other facilities that could be affected by this
deficiency.
(vii) The deficient arc chutes are currently on hold and will not be
released for installation until appropriate corrective actions
are identified that allow proper installation of the arc chute.
Discussions between CPS and Westinghouse (Cutler-Hammer) are
continuing in an attempt to resolve this issue.
(viii) IP has no advice about this issue for other purchasers or
licensees.
Additional information about this issue may be obtained by
contacting D. G. Lukach, Plant Engineering, at (217) 935-8881, extension
3952.
Sincerely yours,
Wayne D. Romberg
Assistant Vice President
RSF/krk
cc: NRC Clinton Licensing Project Manager
NRC Resident Office, V-690
Regional Administrator, Region III, USNRC
G. C. Wright, Region III, USNRC
Illinois Department of Nuclear Safety
INPO Records Center
Westinghouse
Eaton Cutler-Hammer
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