ML17305B313
| ML17305B313 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 01/07/1991 |
| From: | Zimmerman R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| NUDOCS 9101160010 | |
| Download: ML17305B313 (10) | |
See also: IR 05000528/1989056
Text
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UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION V
1450 MARIALANE,SUITE 210
WALNUTCREEK, CALIFORNIA94596
January
7,
1991'ocket
Numbers 50-528,
50-529,
and 50-530
Arizona Public Service
Company
P.O.
Box 53999, Station
9012
Phoenix, Arizona
85072-2034
Attention:
IIr. W. F.
Conway
Executive Vice President,
Nuclear
Gentlemen:
SUBJECT:
REPLY TO APS
LETTER REGARDING DIAGNOSTIC EVALUATION
TEAN REPORT
NOTICE OF VIOLATION (INSPECTION REPORT
50-528,
529, 530/89-56)
. In
a letter dated July 17,
1990,
a Notice of Violation was issued related to
the findings from the Diagnostic Evaluation
Team Report for the Palo Verde
Nuclear Generating Station.
You provided
a response
to the Notice of
Violation in a letter dated August 31,
1990.
In that response
you admitted
some of the violations and while you disagreed
with certain violations, you
stated that the underlying concerns
associated
with these violations were
addressed.
We will review your corrective actions to the violations
and the
issues
raised in the Diagnostic Evaluation
Team Report in subsequent
inspections.
Enclosure
1 to this letter provides our reply regarding
those violations
which you contest d.
In sumIary, after careful review of your response
and
discussions
with your staff,
we have concluded that the contested
violations
should
be withdrawn.
For these violations our records will be modified to
reflect withdrawal of the violations.
In accordance
with 10 CFR 2..790 of the
NRC's "Rules of Practice",
a copy of
this letter and the enclosure will be placed in the
NRC's Public Document
Room.
Should you have any questions
concerning this letter,
we will be pleased
to
discuss
them with you.
Sincerely,
Division of Reactor Safety
and Projects
9101160010 910i07
ADOCK 05000'M8
8
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January
7
1991
cc w/enclosure:
Nr. 0. Nark OeHichele,
Mr. James
M. Levine,
Nr. Jack
hl. Bailey,
Nr. E.
C. Simpson,
Nr. Blaine E. Ballard,
Nr. Thomas
R. Bradish,
Nr. Robert
W. Page,
Nr. Arthur C. Gehr, Esq., Snell
5 Milmer
Hr. Al Gutterman,
Newman
5 Holtzinger P.C.
Mr. Charles
R. Kocher, Esq., Assistant Council,
SCE Company
Mr. James
A. Boeletto, Esq.,
SCE Company
Mr. Charles
B. Brinkman, Combustion Engineering,
Inc.
Hr. Charles Tedford, Oirector, Arizona Radiation Regulatory
Agency
Chairman,
Haricopa
County Board of Supervisors
Nr . John
M. Norman, Chief, Arizona Corporation
Commission
January
7,
1991
bcc:
J. Martin,
RV'.
Faulkenberry,
RV
A. Johnson,
RV
G.
Cook,
RV
Resident
Inspector
Project Inspector
M. Smith,
RV
J. Zollicoller,'V
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RESPONSE
TO CONTESTED VIOLATIONS
DIAGNOSTIC EVALUATION TEAM REPOPT
NOTICE OF VIOLATIOH
On July 17,
1990,
a Notice of Violation was issued for violations identified
during an
NRC Diagnostic Evaluation.
The licensee
responded
to the Notice on
August 31,
1990.
In the licensee's
response,
the licensee
admitted
seven of
the violations and contested
the validity of four violations.
A summary of
the licensee's
response
for the contested
violations and our evaluation
and
conclusions
are
as follows:
A.
Violation I.B.2 -
This violation involved the failure to track the
number of cycles of an overthrust condition which occurred
on Limitorque
motor operators
to assure
that the maximum number of cycles
recommended
by
Limitorque were not exceeded.
The licensee
responded
that because of
the design conservatism of the Limitorque actuators,
the actual final
design thrust limit is 110 percent of the published rating.
While at
one time torque switch trip setpoints
were above
100 percent,
the final
thrusts for these
valves did not exceed
110 percent
as evidenced
by
MOVATS testing
and
APS engineering
evaluation.
In addition,
the
licensee
states
that Limitorque recommends
replacement of the actuator
after
100 cycles
when the torque switch setpoints
are set at 110 percent
of the rated thrust and that
APS does not set these setpoints
such that
the final thrust would exceed
110 percent.
NRC response
-
In that the final actual thrusts for motor operated
valves
were
shown
by analyses
or actual testing to not exceed
110
percent of the rated thrust,
the
NRC agrees
that
a violation as stated
in
the Notice of Violation did not occur and therefore,
this violation
should
be withdrawn.
B.
Violation I.B.3 -
This violation involves the apparent
contradiction
between
Notes
14 and
15 of Document 13-J-ZZI-004 related to the removal
of torque switch limiter plates.
The licensee
disagrees
that the notes
are contradictory
and that the limiter plate
does
not act as
a locking
device.
The licensee
argues
that the limiter plates
were installed
by
Limitoraue to control the maximum torque switch settings
and that
because:
(I) APS is now using
MOVATS to set the torque switch settings,
and (2) torque switch setpoints
are established
in the
MOV data
base
document, administrative controls are sufficient to control the settings
when the limiter plate must
be removed to increase
the switch setting
above the range of the limiter plate.
NRC response
- It is the
NRC's view that Notes
14 and
15 are at best
confusing
as to whether torque switch limiter plates
should
be left in
place or not following MOVATS testing.
Note
14 apppears
to recommend
leaving the limiter plate in place if possible after testing,
and Note
15 appears
to recommend
not installing the limiter plate after testing.
Based
on discussions
with APS personnel,
we have confirmed that the
basis of the maximum thrust values in Document 13-J-ZZI-004 assure
that
the design basis of the valve and valve components
are maintained
and that
MOVATS testing assures
that the torque switch setpoints
are within the
values established
in the
MOV data
base
document.
Therefore,
in the
event that torque limiter plates
are
removed after
NOVATS testing, there
is assurance
that valve design requirements
are met.
We note that Limitorque Maintenance
Update 89-1, in discussing
maximum
torque switch settings,
states,
"Removal of the torque switch limiter
plate to obtain
a higher torque switch setting risks the possibility of
damage
to the valve/actuator
or exceeding
the motor's ability to
generate
output torque"
and "Limitorque does
not recommend
removal of
the torque switch limiter plate."
These
statements
and recommendations
clearly caution against
the removal of the limiter plate.
While we conclude
a violation did not occur,
we recommend that
carefully consider the benefits of maintaining the torque limiter plates
in place for all HOVs.
Violation I.C.3 -
This violation involves the apparent failure to
follow work instructions in that
a diesel
generator cylinder cock was
apparently left open after completion of a work order.
The licensee
disagrees
that
a violation occurred in that
a
Human Performance
Evaluation
was performed,
and
APS concluded that the valve was closed
following maintenance,
but may have
opened slightly as
a result of
engine
cooldown or vibration.
The licensee
indicates that if the
cylinder cock was left open during testing,
the increase
in diesel
engine noise would readily indicate
an open cylinder cock.
NRC response
-
In that the exact causal
factor has not been
determined
for why the cylinder cock was found slightly open
and in that the
licensee's
explanation
may be as probable
as
any other,
the
NRC concludes
that this violation should
be withdrawn.
Violation II.A -
This violation involves the apparent failure of the
licensee to take appropriate corrective actions to preclude repetition
of the bending of an Auxiliary Feedwater
valve stem.
During replacement
of a bent valve stem,
the licensee
apparently did not recognize
the
cause of the bent stem and during the maintenance
process
bent the
replacement
stem.
The licensee
disagrees
with the violation in that the
original valve stem was bent due to material strength
problems
and the
replacement
stem was bent
as
a result of a different problem,
namely
torque switch setpoint drift.
Since these
two problems
are unrelated,
the licensee
argues that corrective actions for the original problem
would not have precluded
the bending of the replacement
stem to the
extent that it was caused
by setpoint drift.
NRC response
-
Based
on the response
provided by APS and discussions
with APS personnel, it appears
that while some as-found information was
lost regarding the original identification of the bent valve stem issue
in Unit 3, enough information was available to conclude that
an
inappropriate
torque switch setting
was not
a concern
and that spring
pack relaxation
was considered
as
a reason
that the motor was burned out
with the torque switch contacts
in the closed position.
APS focused
on
the valve stem material properties.
This was eventually confirmed in
subsequent
evaluations.
The
NRC agrees
that this violation should
be
withdrawn.