ML17305B308
| ML17305B308 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/27/1990 |
| From: | Zimmerman R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| Shared Package | |
| ML17305B309 | List: |
| References | |
| NUDOCS 9101150060 | |
| Download: ML17305B308 (7) | |
See also: IR 05000528/1990042
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UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION V
1450 MARIALANE,SUITE 210
WALNUTCREEK, CALIFORNIA94596
DEC sv
teSP
/
Docket Nos.
50-528,
50-529,
and 50-530
Arizona Public Service
Company
P. 0.
Box 53999, Station
9012
Phoenix, Arizona
85072-3999
Attention:
Mr. W. F.
Conway
Executive Vice President,
Nuclear
Gentlemen:
Subject:
NRC Inspection of Palo Verde Units 1,
2 and
3
This refers to the electrical distribution system functional
(EDSFI)
team
inspection
conducted
by Mr. C.
W. Caldwell, and other
NRC and contractor
personnel
from October
1 through November 9, 1990,
and review of additional
licensee
provided information through
November 23, 1990, involving activities
authorized
by NRC License
Nos.
and NPF-74,
and to the
discussion of our findings held by the inspectors
with members of the Arizona
Nuclear Power Project staff at the conclusion of the inspection
on November 9,
1990.
e
Areas examined during,this inspection
are described
in the enclosed
inspection
report.
Within these areas,
the inspection consisted of selective
examinations of electrical distribution system
(EDS) design calculations,
relevant
procedures
and representati.ve
records,
installed equipment,
interviews with personnel,
and observations
by the inspectors.
Based
on the results of this inspection, it appears
that several of your
activities were not conducted
in full compliance with NRC requirements,
as set
forth in the Notice of Violation, enclosed
herewith
as Appendix A.
Your response
to this Notice is to be submitted in accordance
with the
provisions of 10 CFR. Part 2.201,
as stated in Appendix A, Notice of Violation.
We are particularly concerned with deficiencies related to calculations
supporting the adequacy of the electrical distribution system
(EDS).
Specifically, the inspection
team noted
a number of examples
where the
original design calculations
were either missing or inadequate
to demonstrate
the adequacy of the
EDS design to meet General
Design Criteria
(GDC) 17
requirements
under worst case conditions.
For example,
the effects of the
addition of non-Class
1E loads
(40 MVA) being automatically transferred
from
the unit auxiliary transformer to the startup transformer
on a fast bus
transfer
and the effects of this additional
load on the evaluated
voltages to
safety related
components
were not considered.
Subsequent
APS calculations,
performed in response
to the team findings, confirmed that the
EDS design will
satisfy the requirements
of GDC 17, with the exception of the following case.
910i150060 90i227
ADDCK 05000528
8
~~50 /
It appears
that the offsite power system was.not designed to preclude
the
simultaneous failure of both 'sources
when the three units are powered from two
startup transformers
and
a fast bus transfer of non-Class
1E loads
from the
unit auxiliary transformer to the startup transformer occurs in one unit with
another unit in startup.
In response
to the team finding, APS identified five
occasions
in which the rating for the secondary winding of at least
one
startup transformer would have
been
exceeded ii'
or loss of coolant accident
had occurred in one of the units.
On one of these
occasions,
excess
current
may have occurred
on the secondary of two startup
transformers that were supplying power to Unit 2 if one of the above scenarios
had taken place.
This may have resulted in a loss of both offsite power
sources
to Unit 2.
As
a result, administrative controls for the loading of
the startup transformers
were implemented
by the licensee.
The team also noted several
examples of errors in original design
calculations.
For example,
non-conservative
load values
were
used for a load
center
and
a calculation involving a plant design modification on the spray
pond system
had the wrong information concerning the maximum spray
pond level.
During the exit meeting,
the team emphasized
that since
APS has not yet
performed
a great deal of design modification work, now is
a significant
opportunity to correct current
and past design control weaknesses
which have
allowed deficiencies,
such
as those
noted
by the team, to occur.
We understand that
a design basis reconstitution effort is in progress
and
that
APS intends that calculation
problems
such
as those
noted by the team
will be identified and corrected
by; this effort.
However,
we also note that
although
APS has
completed electrical
systems reliability assessments,
these
efforts failed to identify the significant discrepancies
noted by the team.
In this regard,
we consider that current
and future efforts should
be
performed with more careful attention to detail
and that efforts should
specifically challenge
and confirm the original design assumptions.
In
addition, integration of the
NRC team's
inspection findings should
be factored
into your efforts.
Due to the significant problems noted, it is requested
that you provide an appraisal
of why these discrepancies
were not identified
in any of your previous
EDS assessments.
The inspection
team noted that relatively little design margin remains
on the
diesel
generators
and other components.
Accordingly, we also encourage
you to
better integrate
the various engineering
and quality oversight functions to
enhance
performance in the engineering
and technical
support area,
to ensure
that'adequate
EDS design margins continue to be maintained.
We will review
your corrective actions in response
to the Notice of Violation and your
continued
program enhancements
during future inspections.
In accordance
with 10 CFR Part 2.790(a),
a copy of this letter and the
enclosures will be placed in the
NRC Public Document
Room.
The responses
directed
by this letter and the accompanying
Notice are not
subject to the clearance
procedure of the Office of Management
and Budget
as
required by the Paperwork Reduction Act of 1980,
PL 96-511.
E.
0
0
Should you have any questions
concerning
thi.s inspection,
we will be pleased
to discuss
them with you.
Sincerely,
R. P.
Zimaerman, Director
Division of Reactor Safety
and Projects
s
Enclosure:
1. Appendix A - Notice of Violation
2. Inspection Report Numbers 50-528/90-42,
50-529/90-42,
and
50-530/90-42
cc w/enclosures:
Mr. Jack
N. Bailey,
8r. Blaine E.. Ballard,
Mr. Thomas R..Bradish,
Mr. 0. Mark De.Michele,
Mr. James
M. Levine,
Mr. Robert
W. Page,
Mr. E.
C. Simpson,
Mr. Arthur C. Gehr, Esq., Snell
8 Willmer
Mr. Al Gutterman,
Newman
8 Holtzinger,
P.
C.
Mr. Charles
R. Kocher, Esq., Assistant Council,
SCE Company
Mr. James
A. Boeletto, Esq.,
Company
Mr. Charles
B. Brinkman, Combustion Engineering,
Inc.
Mr. Charles Tedford, Director, Arizona Radiation Regulatory Agency
Chairman,
Maricopa County Board of Supervisors
Mr. John
W. Norman, Chief, Arizona Corporation
Commission
0
bcc w/enclosures:
Docket File
Resident
Inspector
Project Inspector
G.
Cook
B. Faulkenberry
J. Hartin
A, Johnson
bcc w/o enclosure
2:
N. Mester.n~ J. Zollicoffer
M. Smith
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