ML16342C730
| ML16342C730 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/07/1994 |
| From: | Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML16342C729 | List: |
| References | |
| 50-323-94-28, NUDOCS 9411170047 | |
| Download: ML16342C730 (16) | |
See also: IR 05000323/1994028
Text
APPENDIX B
U.S.
NUCLEAR REGULATORY COMMISSION
REGION IV
Inspection Report:
50-323/94-28
License:
Licensee:
Pacific
Gas
and Electric Company
77 Beale Street,
Room 1451.
P.O.
Box 770000
San Francisco,
Facility Name:
Diablo Canyon Nuclear
Power Plant, Unit
2
Inspection At:
Diablo Canyon Site,
San Luis Obispo County, California
Inspection
Conducted:
October
19-28,
1994
Inspector:
H. Tschiltz, Resident
Inspector
Approved:
.
K rsc
,
C i
, Reactor
Prospects
rane
t
Ins ection
Summar
D te
Areas
Ins ected
Unit 2
A special
inspection of the circumstances
associated
with the loss of residual
heat
removal
(RHR) cooling during diesel
generator
(DG) testing
on October
18,
1994.
During the inspection,
Inspection
Procedures
92901
and
92703 were used.
Areas
Ins ected
Unit
1
No inspection of Unit
1 was performed.
Results
Unit 2
On October
18,
1994, during
DG surveillance testing,
the failure of licensee
personnel
to follow the procedural
requirements
resulted
'in the inadvertent
shutdown of the
RHR pump providing cooling to the core.
After a period of
approximately
6 minutes the control operator
noted that the'running
RHR pump
had
been de-energized
during the testing
and restarted
the
RHR pump.
Prior to
de-energizing
Bus H, there were two separate
steps
in the procedure
which, if
performed properly,
would have identified that
RHR Pump 2-2 should not be in
operation during the testing which de-energized
4 kv Bus H.
Additionally,
a
note in the procedure
should
have alerted operators
to the fact that
Pump 2-2 should not
be in service to support
any critical plant operations
during the testing.
9411170047
941109
ADOCK 05000323
9
0
Plant
0 erations
Weaknesses:
The inspection identified two instances
of operator failure to follow
surveillance
procedure
requirements
which resulted
in the loss of RHR
cooling flow through the core.
A detailed tailboard
was not conducted prior to performing the
surveillance.
Neither the shift foreman nor shift supervisor
were
involved with the discussion
of DG testing.
The tailboard conducted
by
the operator
and
system engineer did not meet
management
expectations
for integrated
plant testing.
~
The shift foreman did not provide adequate
oversight of testing which
had the 'potential to impact core cooling.
The level of involvement
by
the shift foreman did not meet
management
expectations
for integrated
plant testing.
~
The control operator failed to adequately
consider the effect of the
surveillance test
on core cooling.
A visual examination of the control
boards to identify components
that would be de-energized
during the
surveillance test failed to identify that
RHR Pump 2-2 was in operation.
t
~R1 i:
N
pl i
b1
Summar
of Ins ection Findin s:
~
Violation 323/94-28-01
was identified (Section 2).
Attachment:
~
Attachment
I - Persons
Contacted
and Exit Heeting
~
Attachment
2
0
'
DETAILS
1
BACKGROUND
At the time of the Diablo Canyon Unit 2 loss of RHR cooling,
on October
18,
1994,
the unit was in Mode
5 with a reactor coolant
system temperature
of
96'F.
The unit was in the 25th day of 'Refueling Outage
2R6.
Core reload
was
complete
and both trains of RHR were available.
RHR Pump 2-2 was running
and
powered
from 4 kv Bus
H.
DG surveillance testing
was being performed that
required vital
4 kv Bus
H to be de-energized.
Pump 2-2 was improperly
left in service during this testing.
When power to 4 kv Bus
H was secured,
per the surveillance,
DG 2-2 autostarted
and aligned to re-energize
4 kv
Bus
H; however,
as expected for the autoload feature
under test,
the
RHR pump
did not autoload
back onto the
4 kv bus
~
The de-energization
of RHR
Pump 2-2
resulted
in the loss of core cooling.
The loss of RHR flow was noted
by the
control operator
approximately
6 minutes after the
pump was de-en'ergized,
at
which point
Pump 2-2 was restarted.
During the interruption of core
cooling core temperature
increased
approximately 6'F from 96 to 102'F.
" The
licensee
made
a 4-hour nonemergency
report regarding this event to the
NRC in
accordance
with 10 CFR 50.72(b)(2)(iii)(B).
2
DG SURVEILLANCE TESTING
2. 1
DG 2-2 Autostart
and
Load Transfer Testin
On the evening of October
18,
1994,
DG 2-2 testing
per Surveillance
Test
Procedure
STP M-9G, Revision
18,
"Diesel Generator
24-Hour Load Test,"
was
performed which involved the
demonstration
of autostart
and load transfer
functions.
The autostart
portion of the test involved running
DG 2-2 at full
load for
1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or until operating
temperature
stabilized,
unloading
and
securing
the
DG, opening the auxiliary power feeder breaker
supplying the
4 kv
bus associated
with the
DG being tested,
and verifying that the
DG autostarted
and loaded onto the
bus within 10 seconds.
The load transfer portion of the
test verified that breakers for 4 kv auto-connected
loads closed
onto the
bus
after the
DG breaker closed.
A licensed operator
was assigned
to operate
and align equipment
per
STP M-9G,
as required,
during the test.
A system engineer
was assigned
to the testing
team to provide technical
guidance if required during testing.
Control
room
equipment alignments,
required during the performance
of STP M-9G, were
accomplished
by the licensed operator with the surveillance
procedure
in hand.
Changes
in equipment
lineups
were communicated
to the control operator.
In preparation for the autostart
auto load test portion of STP M-9G, the
procedure
specified
alignment of Vital Bus
H equipment.
Systems
and
components
affected
by the loss of 4 kv Bus* H power were required to be
realigned, prior to de-energizing
the bus,
to ensure
the test did not
adversely
impact plant operation.
Step
12.3. I.e.4, stated,
in part, that
"The
following equipment will not autostart
in this test
and must
be shut
down:
a)
0
0
'
Pump
No.
2
b) Containment
Spray
Pump
No.
2 c) SIS
Pump
No. 2."
This step
was initialed by the operator
as complete
in error,
since the
RHR pump was not
secured.
Immediately following Step
12.3. l.e-.4, the procedure
contained
a
note which explains that these
4 kv bus
H loads
are secured
because
the load
shed signal,
which is generated
during the test, will trip the breakers
supplying
power to the
pumps if they are in service.
The note additionally
cauti'oned that "if the autotransfer
signal
cannot
be reset
these
pumps
can not
be manually restarted"
and concludes with the statement
that "these
pumps
should not be in service to support
any critical plant operations."
At a subsequent
point in the procedure,
prior to securing
the power to
4 kv
Bus
H, Step 12.3.2.g.
1 required that
a review be performed to verify that the
equipment lost. due to the transfer will not place the plant in a Technical
Specification
(TS) action statement.
The step
was initialed as being
completed
by the operator;
however,
the operator did not identify that the
operating
RHR pump
was
powered
from 4 kv Bus
H and that securing
power to
4 kv
Bus
H would result in the entry into TS 3.4. 1.4. 1 action statement.
1 requires that
one
RKR train be operable
and in operation
when in
Mode
5 with the reactor coolant loops filled.
Prior to securing
the auxiliary power feed to the bus,
the control operator
discussed
the
sequence
of events
from de-energizing
the
bus to the
autostarting of the loads with the operator.
The shift foreman
was informed
.
when the portion of the test which de-energized
the bus
commenced.
The
control operator
scanned
the control
board to determine
which loads would be
lost during the transfer.
During the scan,
the control operator did not
identify that the running
RHR pump would be stripped
from the
bus during
testing.
Caution tags were'hanging
on the control
board which obscured
the
control operator's
view of color coded labeling indicating equipment
power
sources;
however,
the tags did not obscure
Pump 2-2 running light
indication.
The control operator did not recognize that the running
RHR pump
would be affected
by the surveillance.
Conclusion
The two instances
where the operator failed to follow the instruction of the
surveillance test procedure,
STP M-9G, are
examples of failure to follow
procedural
requirements
and are
a violation of TS 6.8. 1.
TS 6.8. 1 requires
that written procedures
shall
be established,
implemented,
and maintained
covering the applicable
procedures
recommended
in Appendix
A of Regulatory
Guide 1.33,
Revision 2, including procedures
covering the performance of
surveillance tests
on emergency
power systems
{Violation 323/9428-01).
2.2
Tailboard
and
Su ervision
Involvement
During the previous
performance
of STP
M-9G for DG 2-2 on October
17,
1994,
DG 2-2 failed to meet the acceptance
criteria for time to hot restart
and load
onto the bus.
The actual
time for this portion of the testing
was greater
than
10 seconds,
which is the maximum allowable per the surveillance
procedure.
The licensee's
preliminary review of the conditions in effect
!
during the test indicated that the failure to meet the test criteria was
related to the slow rate of voltage decrease
following the opening of the
auxiliary feeder breaker.
NRC review of the initial failure of DG 2-2 to meet
the acceptance
criteria will be documented
in NRC Inspection
Report 50-
323/94-27.
On October
18,
1994,
the shift foreman
made the decision to not conduct
a
tailboard for the
STP M-9G testing
scheduled for the evening of October
18,
1994.
This decision
was
based
on the shift foreman's
assessment
that the
involved system engineer
and operator familiarity with STP
M-9G was
acceptable,
in part,
because
portions of STP
M-9G had
been
performed
by the
operators
and the
system engineer
the previous day.
Neither the shift foreman
or the senior control operator
were directly involved with supervision
or
oversight of the
M-9G testing prior to commencing
the testing which
resulted
in de-energizing
the running
RHR pump.
The shift foreman relied upon
the system engineer to conduct the test with the operator.
The system
engineer
and the operator did review portions of the test procedure
together
prior to performing the test.
The review included
a basic overview of the
sequence
of the test
and
DG limitations.
The control operator participated
in
a portion of the test review for the discussion of the electrical
loads which
would be de-energized
during the test
and the loads which would autoload
onto
4 kv Bus
H.
During this review the system engineer
explained that all
Bus
H
loads
would initially be de-energized
during the test.
The operator's
primary
concern
was the
480 volt loads which were to be de-energized
and the loads
which were to autoload
onto the
bus during the test.
Conclusion
The decision of the shift foreman to not
be involved with critical portions of
the testing involving de-energizing
Bus
H was not in accordance
with
management
expectations
for integrated plant testing.
Additionally, the
decision that
a formal tailboard for the
DG testing
was not required
was not
in accordance
with management
expectations
for the conduct of tailboards.
As
a result of these
problems,
licensee
management
has initiated actions to
reinforce expectations
for the conduct
and content of tailboards.
'.3
S stem
En ineer Involvement with Surveillance Testin
The authority and responsibilities of the system engineer during the
surveillance test were not clearly understood.
Perso'nnel
involved with the
test
had differing views of the system engineer's
role during the test.
The
system engineer role in the performance of testing is defined in licensee
administrative
Procedure
AD13. ID1, Revision
1A, "Conduct of Plant
Equipment
Tests,"
paragraph
5.4.3,
which states, "if technical
guidance of testing
activities is needed,
the person
in charge of the test
should contact the
appropriate
System
Engineer
or the procedure's
sponsor."
0
'
Conclusion
There is not
a clear definition or understanding
of system engineer
responsibilities
during system testing.
The involvement of system engineers
with surveillance testing
has
increased
with the shortened
outage periods.
The
NRC views the increased
involvement of the system engineer
as
a strength
of the outage testing
program;
however,
increased
system engineer
involvement
without clear definition of system'engineer
responsibilities
during the
conduct of testing creates
an increased
potential for errors in
communications.
The licensee
is reviewing the-need for more clearly
establishing
the role of the system engineer during the conduct of testing.
0
'
1
PERSONS
CONTACTED
ATTACKHENT 1
1. 1
Licensee
Personnel
G.
H. Rueger,
Senior Vice President
and General
Manager,
Nuclear
Power
Generation
Business
Unit
J.
D. Townsend,
Vice President,
Nuclear Technical
Services
- W. K. Fujimoto, Vice President
and Plant Manager,
Diablo Canyon Operations
R.
P.
Powers,
Manager,
Nuclear guality Services
- H. J.
Angus,
Manager,
Nuclear Technical
Services
D.
B. Barkley, Shift Foreman,
Operations
S.
Bednarz,
System Engineer,
Systems
Engineering
- C.
C
Belmont, Auditor, equality Assurance
- B. J.
Berndt,
Engineer,
Regulatory
Compliance
- T. L. Grebel,
Superv,isor,
Regulatory
Compliance
- W. G. Crockett,
Manager,
Technical
and Support, Services
- S.
R. Fridley, Director, Operations
C.
H. Harvey, Control Operator,
Operations
- J.
R. Kinds, Director, Nuclear Safety Engineering
- K. A. Hubbard,
Engineer,
Regulatory
Compliance
H,
S.
Lemke, Shift Supervisor,
Operations
- D. B. Hiklush, Manager,
Operations
Services
- D. K. Oatley, Director, Materials Services
- R. Ortega,
System Engineer,
Systems
Engineering
- J. L. Portney,
System Engineer,
Systems
Engineering
J.
B. Whetsler,
Nuclear Operator,
Operations
1. 2
NRC Personnel
- H. Tschiltz, Resident
Inspector
- Denotes those attending
the exit meeting
November
2,
1994.
In addition to the personnel
listed above,
the inspectors
contacted
other
personnel
during this inspection period.
I
2
EXIT MEETING
An exit meeting
was conducted
on November
2,
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.
'
KV
TS
ATTACHNENT 2
ACRONYHS
Diesel
Generator
Ki 1 o-volt
residual
heat
removal
Technical Specification
surveillance test procedure
I