ML16343A237
| ML16343A237 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/06/1994 |
| From: | Howell A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML16342C618 | List: |
| References | |
| 50-275-94-21, 50-323-94-21, GL-89-13, NUDOCS 9407130018 | |
| Download: ML16343A237 (8) | |
See also: IR 05000275/1994021
Text
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APPENDIX
U.S.
NUCLEAR REGULATORY COMMISSION
REGION IV
Inspection Report:
50-275/94-21
50-323/94-21
Licenses:
DPR-82
Licensee:
Pacific
Gas
and Electric Company
(PG&E)
77 Beale Street,
Room
1451
P.O.
Box 770000
San Francisco,
Facility Name:
Diablo Canyon Nuclear
Power Plant, Units
1 and
2
Inspection At:
Pacific Gas
& Electric Corporate offices
333 Market Street
San Francisco,
94177
Inspection
Conducted:
Hay 24,
1994
Inspector:
P. Narbut,
Regional
Team Leader, Division of Reactor Safety
Approved:
owe
,
epu y
erector
Division of Reactor Safety
te
Ins ection
Summar
Areas
Ins ected
Units
1
and
2
Routine,
announced
inspection of PG&E's
activities performed in response
System
Problems Affecting Safety-Related
Equipment,"
issued
on July 18,
1989.
The inspection
examined
some additional questions that
had arisen
subsequent
to the inspection reported in NRC Inspection
Report 50-275/94-08;
50-323/94-
08.
Temporary Instruction (TI) 2515/118
and Inspection
Procedure
40500 were
used
as guidance during this inspection.
Results
Units
1
and
2
The licensee satisfactorily resolved the concerns
developed
subsequent
to the issuance of NRC Inspection
Report 50-275/94-08;
50-323/94-08.
Attachment:
~
Attachment - Persons
Contacted
and Exit Meeting
9407i300i8 940707
ADOCK 05000275
9
0
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DETAILS
1
FOLLOWUP IWESTIONS REGARDING AUXILIARYSALT WATER SYSTEN OPERABILITY
1.1
~Back round
The
NRC issued
System
Problems Affecting
Safety-Related
Equipment,"
on July 18,
1989.
The generic letter described
recurring industry problems with the service water systems
at nuclear
power
plants.
Service water systems
are important to plant safety
as the ultimate
heat sink following a design basis event.
The generic letter recommended
certain actions to be taken
by licensees
and required that each licensee
advise the
NRC of the programs to be implemented
in response
to the generic
letter recommendations.
PG&E Letter No. DCL-90-027, dated January
26,
1990,
provided
PG&E's response
to the generic letter and: hommitted to perform
certain actions.
PG&E Letter No. DCL-91-286, dated
November 25,
1991,
provided
a supplemental
response
to the generic letter
and reported the
completion of the initial program actions.
NRC Inspection
Report 50-275/93-36;
50-323/93-36
examined the licensee's
actions taken in response
The inspection report
identified
a number of unresolved
and followup items regarding the adequacy of
the licensee's
actions
taken in response
to the generic letter,
and requested
that the licensee
address
the items in a written response
to the
NRC.
The
licensee
provided
a response
to the inspection report in
PG&E Letter No. DCL-
94-037,
dated
February
15,
1994.
The response
addressed
each of the
inspection
items
and stated that there were instances
in 1987
and
1990 when
the Auxiliary Saltwater
System
(ASW) may not have
been operable.
The response
also stated that
a supplemental
response
would be provided when the results of
the past operability study were completed.
The results of that past
operability study were documented
in Licensee
Event Report
(LER) 1-93-012-01,
"Auxiliary Saltwater
System Outside Design Basis
Due to Fouling," dated
Harch 8,
1994.
NRC Inspection
Report 50-275/94-08;
50-323/94-08 followed up the issues
identified in NRC Inspection
Report 50-275/93-36;
50-323/93-36,
closed the
majority of the unresolved
items,
and described
three
apparent violations to
be addressed
by separate
correspondence.
This inspection
examined
several
concerns
regarding the licensee's
studies of
ASW operability which had arisen during the period subsequent
to the issuance
of NRC Inspection
Report 50-275/94-08;
50-323/94-08.
1.2
Case Studies with Low Flows
The licensee
had performed
a number of case
studies to demonstrate
ASW system
operability.
The cases
were numbered
"A" to "S" and were described
as
evolutionary in that the cases
evolved into the cases
the licensee
considered
to be realistic representations
of the relevant plant parameters
in effect
0
"
-3-
during the periods of high microfouling and high macrofouling.
Some of the
case
studies
which the licensee
performed
(Cases
C,
G, J,
and
L) had flows in
the 9000-10,000
gpm range,
whereas
the cases
the licensee
considered
to be
most representative
(Cases
0 and
P)
had flows in the 11,000
gpm range.
The
concern
arose
as to why the lower flow cases
weren't utilized.
The licensee
demonstrated
that the lower flow cases
were based
on the lowest
flow recorded for ASW flow Refueling Cycle 4.
This value was
11,008
gpm which
occurred
on January
5,
1990.
The flow value
was then projected
downward to
account for low tide,
a crosstie configuration,
instrument error,
and
maximum
macrofouling differential pressure.
The result
was
a flow of 9886
gpm used in
Cases
G and
L and
a slightly higher flow of 9968
gpm in Cases
C and J due to a
small error in the tide calculation.
The licensee utilized flows of 11,676
and 11, 196
gpm for Cases
0 and
P
respectively.
Case
0 was the study of the period of high microfouling in
August
1990
and
Case
P was the period of high macrofouling in 1987.
The
licensee utilized what they considered
to be more realistic flow data (rather
than the minimum recorded flow) which was
an average
flow derived from flow
data from their quarterly
ASHE pump performance tests.
The licensee
did not
use data from their monthly tests
because
the statistical
deviations for that
data were higher than the deviations for the quarterly test data.
This was
not
a conservative
decision since the monthly data
was generally slightly
lower than the quarterly data.
Both data sets
are derived from the
same
annubar flow instruments.
However, the inspector noted that the licensee's
study of data deviation
appeared
to support their decision that the quarterly
data
was more accurate.
During the inspection,
the licensee
performed 'an
estimate that use of the more conservative
monthly data would have resulted in
higher calculated
CCW temperatures
of only 0. 15-0.20 'F, which was not
significant to the conclusions of the operability study.
Additionally the licensee
corrected
the raw annubar
averages
upward by about
500 gpm, or about 4.5 percent of the total flow, based
on recently developed
flow measurement
correlation data which showed that the annubar data
was low
compared to actual flow as measured
by more accurate
dye dilution flow
measurement
methods.
The inspector concluded that although this could be
viewed
as another non-conservative
approach,
the licensee
had compensated
by
utilizing more conservative
time/temperature
blocks or envelopes
in their
equipment operability evaluations.
These time/temperature
blocks
conservatively
enveloped
the detailed time/temperature
curves which resulted
from the licensee's
calculations,
and were used to evaluate
the increased
temperature
effects
on equipment operability.
The inspector therefore
concluded that the Case
0 and
P flow data
used for the
licensee's
operability analysis
was reasonable.
The flow data
was not as
conservative
as it could have
been but the use of a more conservative
approach
would not have affected the ultimate conclusion that the system
had
been
but not within design basis during the periods of high microfouling
and high macrofouling.
0
~TTACHNENT
1
PERSONS
CONTACTED
1.1
Licensee
Personnel
- H. Angus,
Manager,
Technical
and Support Services
- T. Grebel, Supervisor,
Regulatory
Compliance Supervisor
- J. Kelly, Mechanical
Group Leader,
Nuclear Engineering Services
- H. Leppke, Assistant
Manager,
Technical
and Support Services
- J. Sexton,
Manager,
Nuclear Regulatory Services
K. Smith, Hechanical
Engineer,
Nuclear Engineering Services
G. Starnes,
Mechanical
Engineer,
Technical
and Ecological Services
1.2
Contracto
for Pacific
Gas
and
ectric
Com an
F. L. Steinert,
Senior Scientist,
Aquatic Systems
Inc.
- Denotes those attending the exit interview on May 24,
1994.
2
EXIT MEETING
An exit meeting
was condu'cted
on Hay 24,
1994.
During this meeting,
the
inspectors
reviewed the scope
and findings of the report.
The licensee
acknowledged
the inspection findings documented
in this report.
The licensee
did not identify as proprietary
any information provided to, or reviewed by,
the inspectors.
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