ML17286B211
| ML17286B211 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 12/11/1991 |
| From: | Johnson P, David Proulx, Sorensen R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML17286B210 | List: |
| References | |
| 50-397-91-44, NUDOCS 9112310006 | |
| Download: ML17286B211 (26) | |
See also: IR 05000397/1991044
Text
U.S.
NUCLEAR REGULATORY COMMISSION
REGION
V
Report
No:
Docket No:
Licensee:
Facility Name:
Inspection at:
50-397/91-44
50-397
Washington Public
Power Supply System
P. 0.
Box 968
Richland,
WA 99352
Washington Nuclear Project
No.
2
(WNP-2)
WNP-2 site near Richland,
Inspection
Conducted:
Nove
er
4 - December
8,
1991
Inspectors:
o en
,
en'
ess
t
nspector
.
Prou x,
si ent
nspector
ate
i ne
/2. il
a
e
igne
Approved by:
~Summ au
nson,
se
React
Projects
Section
3
/+/// q/
ate
>gne
S ecial
Ins ection
on November
4
December
8
1991
Re ort No. 50-397 91-44
Areas
Ins ected:
Special
inspection
by the resident
inspectors of various
problems,
both reported
and" NRC-identified, associated
with the containment
atmospheric
control
(CAC) system.
During this inspection,
Inspection
Procedures
61726,
62703,
71707,
71710,
90712,
and
92700 were utilized.
Safet
Issues
Mana ement
S stem
SIMS
Items:
None.
Results:
General
Conclusions
and
S ecific Findin
s
Si nificant Safet
Matters:
The material condition
and operability of
the containment
atmospheric
control
(CAC) system
have not been main-
tained
as required.
Pii"'3iOOOE
Pii213'DR
ADDCVi 05000397
8
(i
F
~
l
')'
1
Summar
of Violations and Deviations:
Four apparent violations were
identified involving the
CAC system,
as follows:
Seismic supports for the
CAC system were not assembled-'as
required
(paragraph
4.a).
The "A" Train of the
CAC system
was inoperable
from December
1990
until September
1991
because
of loss of lubricating oil from the
blower housing
(paragraph
5.a).
Both trains of the
CAC system were inoperable
from before initial
plant startup until procedures
were revised in August
1991 to
provide for manual operation,
because
improper recycle flow
controllers
were installed
(paragraph
5.b).
The licensee
did not report the inoperability of both trains of.
CAC (caused
by the use of improper flow controllers) within the
time periods required
by 10 CFR 50.72
and 50.73
(paragraph
S.b).
1t
I)
4
L',
N
DETAILS
1..
Persons
Contacted
- L. Oxsen,
Deputy Managing Director
- J. Baker,
Plant Manager
L. Harrold, Assistant
Plant Manager
- J. Irish,
Program Analyst, Bonneville Power Administration
- R. Webring, Plant Technical
Manager
- A. Hosier,
Licensing Manager
- S. Davison, guality Assurance
Manager
- J. Peters,
Administrative Manager
.
S.
HcKay, Operations
Manager
- K. Worthen, Operations
Engineer
- J. Snyder,
Lead Engineer
P. Inserra,
System Engineer
D. Bosi, Plant Support Engineering
- L. Sharp,
Plant Support Engineering
The inspectors
also talked with other cognizant licensee
represen-
tatives.
- Attended the Exit Heeting
on December
6,
1991.
Back round
The'ontainment
atmospheric
control
(CAC) system is composed of two
redundant, full capacity
hydrogen-oxygen
recombiners
manufactured
by Air
Products
and Chemicals,
Inc., with associated
piping, valves,
and
components.
The system is designed
to Seismic Category
I requirements
and in accordance, with Regulatory
Guide 1.7
and Criterion 41 of 10 CFR 50, Appendix A.
The recombiners
serve to limit the concentration
of
and hydrogen in the primary containment .following a postulated
loss-of-coolant
accident
(LOCA).
The recombiners
are located outside
the primary containment.
Each
CAC train was procured
from the vendor
as
a skid-mounted unit,
and is composed of a water scrubber,
a constant-
speed
blower,
a catalytic recombiner,
and
an aftercooler.
The process
gas
from the containment
atmosphere first enters
the water
scrubber
where particulates,
droplets,
and soluble trace impurities are
removed
by direct continuous
contact with water in a packed
bed column.
After leaving the top of the water column, the gas
passes
through a-
demister which traps
any entrained water (the water, with entrapped
particulates
and dissolved solids,
leaves
the bottom of the scrubber
and
is directed to the suppress.ion
pool).
The gas
then, enters
the blower.
The blower is designed
to provide
a constant
65.7
SCFH flow through the
system
and connected
piping.
The process
gas
then enters
the preheater
where it is heated to'a temperature
of 500 to 550 degrees
F.
Heating of
the gases
to
a temperature
of 500 degrees
prior to their entering the
catalytic recombiner prevents
degradation
of the catalyst
bed
by
halogens that are potentially present
in the process
gas.
The gas
then
enters
the catalytic recombiner,
where
and hydrogen react
on the
catalyst
bed to form water vapor.
The hot effluent gas is then cooled
in the aftercooler;
which utilizes standby service water
as
a heat sink.
The condensate
from the aftercooler is separated
in a moisture separator
and directed to the suppression
pool.
Typically, 55X of the recombiner discharge
flow is recycled
back to the
blower suction.
Thus, the hydrogen/oxygen
mixture that enters
the
blower is diluted by this recycle flow (principally nitrogen).
It is
very important to closely control this recycle flow.
For every IX
concentration of hydrogen in the process
stream,
the catalytic recom-
biner exit temperature will increase
approximately
140 degrees
above the
500 degree
recombiner inlet temperature
supplied
by the preheater.
The
recombiner unit is designed to trip at
an exit temperature
of 1150
degrees.
Thus, insufficient recycle flow could eventually cause
the
unit to trip on high temperature (if containment
hydrogen concentration
were greater
than about.5X).
An important consideration for the
CAC system is that the blower and
motor are enclosed within a steel
vessel.
The vessel
is bolted closed
and
has
no access
port.
The inside of the vessel
is part of primary
containment;
thus,
the blower cannot
be inspected
during normal plant
operation.
3.
Previous
NRC Findin
s
Re ardin
the
S stem
Previous
NRC findings regarding the
CAC 'system
were documented
in
NRC
Inspection
Report
No. 50-397/91-28
(inspection period ending
on
September
17,
1991).
The following is
a summary of those findings.
The inspector
had performed
a detailed
walkdown of the
CAC system to
verify that the plant configuration
and system lineups
were in accord-
ance with the as-built drawings, that system operating
procedures
correctly reflected the
FSAR and as-built drawings, that the material
condition of the system
was satisfactory,
and that vendor-recommended
preventive maintenance
activities were being performed.
The findings in
these
various
areas
can
be categorized
as follows:
a.
Preventive
Haintenance
Some maintenance
activities specifically recommended
in vendor
technical
manuals
were not being addressed
by the licensee.
Although the vendor (Switzer Co.)
recommended
that the lubricating
oil in the
CAC blowers
be changed
every 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> of operation,
or
at least every six months
(whichever
comes first),
a lubrication
schedule
had,not
been established.
The licensee
stated that the
decision
had
been
made during startup that,
since the
CAC blowers
are run on
a very infrequent basis for short periods of time,
a
lubricating oil changeout
frequency of once per 40 years
was suf-
ficient.
Based
on this, the licensee
had
no lubricating schedule
for the
CAC blowers.
No records
were available at the time of the
inspection
documenting that this evaluation
had
been
accomplished.
However, the licensee
stated
at the exit meeting that these
records
would be provided.
It
III
/
Further, it was noted
by the inspector that the licensee's
lubri-
cation schedule for the motor that drives the
CAC blower
was more
restrictive than that for the blower itself, in that the schedule
required the motor's oil to be changed
every five years.
The
vendor technical
manual for the motor recommends
an oil change
every
3 to
9 months, of oper ation, which is much less restrictive
than the vendor recommendation for the
CAC blowers.
It appeared,
therefore,
that the licensee
had used inconsistent
engineering
judgement
in the rationale for developing lubrication schedules
for
these safety related
components.
The licensee
stated
at the exit
meeting that they were planning to establish
a preventive eainte-
nance action to change
the oil in the blowers every five years.
The vendor technical
manual
also
recommends that the blower and
motor should
be
"bumped" at least
once every two weeks
by applying
'power
and rotating .the shaft to a new position.
This is to prevent
flat spots
from developing
on the motor/blower shaft.
The licensee
had not periodically rotated these
fans since plant startup,
and
was unaware of this vendor recommendation.
The system engineer
stated that this could lead to "running the
CAC fans to destruc-
tion," and felt that the biweekly rotation of the fans
was not
warranted.
The inspector noted,
however, that the vendor manuals
guarantee
that the
CAC motors
and blowers
can run for several
years
of continuous operation without failure.
This finding was
especially significant, given that the licensee
found one of .the
CAC blowers seized while trying to conduct
a surveillance test in
September
1991
(see
paragraph
5.a below).
It had apparently
been
seized
since
December
1990, the last time this particular surveil-
lance test
had
been
conducted.
This problem would have
been
discovered
much sooner
had this vendor recommendation
been imple-
mented.
The licensee
stated
at the exit meeting that additional
consideration
was being given to periodically rotating the blowers.
b.
S stem Naterial Deficiencies
C.
While conducting
a walkdown of the
CAC system
(during the previous
inspection),
the inspector
had noted the following labeling or
material condition discrepancies:
The label plates for valves
CAC-V-307A and
308A were reversed.
The label plates for valves
CAC-V-301A and
302A were reversed.
Loose bolts were noted
on, the torque switch cover for CAC-V-6.
Review of CAC 0 eratin
Procedures
PPHs 2.3.3A and 2.3.38
The inspector
had also noted minor discrepancies
in operating
procedures.
No verification and validation
(V&V) had
been
accomplished for them as of the time of the previous inspection.
This was especially significant given that the
CAC operating
procedures
are directly referenced
by the
Emergency
Operating
Procedures
(EOPs).
Discrepancies
noted were:
0
t
il
i
1
I
I
II
V
4
Plant Procedures
Manual
(PPH) Sections
2.3.3A and 2.3.38
directed operators
to use
a key to operate
keylocked switches
for valves
CAC-FCV-lA, 18,
4A, and 48.
None of these
valves
has
a keylocked switch for operation
from the control
room.
PPHs 2.3.3A and 2.3.38 listed drawing H-554, Revision
16,
as
the applicable reference for the valve lineup.
The actual
revision for drawing H-554 in effect during the inspection
period
was Revision 46.
Revision
16 dates
from prior to plant
startup.
CAC-TCV-48 was listed
as
CAC-TCV-48 in
PPH 2..3.38.
The as-built drawing listed the proper position of CAC inter-
face valves
RHR-V-134A and
RHR-V-1348 as open, while PPHs
2.3.3A and 2.3..38 required these
valves to be shut.
Valves
CAC-V-5A and
CAC-V-58 perform identical functions for
Trains
A and
8 of CAC, respectively.
However, the required
position of CAC-V-5A was
open in
PPH 2.3.3A and the required
position of CAC-V-58 was shut in
PPH 2.3.38.
Drawing M-554 and
PPHs 2.3.3A and 2.3.38 listed different
positions for CAC-V-316A and CAC-V-3168 (isolation valves for
similar pressure
gauges).
The licensee
stated that these discrepancies
would probably have
been identified by VEV of the most recent revision to these
proce-
dures.
However, the inspector
noted that these errors
had existed
in these
operating
procedures
through several
previous revisions.
These fiqdings gave
an initial indication, in the aggregate,
of insuffi-
cient attention to proper maintenance
and operation of the
CAC system.
This was addressed
in the cover letter which transmitted
the inspection
report to the licensee.
4.
Additional Findin
s
Re ardin
CAC Maintenance
and Confi uration Control
Additional inspector observations
related to the
CAC system
were
made
during late September
and early October,
1991,
as follows:
a,
While observing
a surveillance test
on
CAC Temperature
Control
Valve (TCV)-4A, just prior to plant startup
on September
26, the
inspector
observed
a 3/4-inch hex nut on the floor of the "A" CAC
skid near
TCV-4A,
This nut appeared
to have
come from CAC piping
restraint
PS-5,
which the inspector
noted
was, not made
up properly.
This restraint
had apparently
been disassembled
for work on TCV-4A,
although the maintenance
work request
(HWR) that authorized
work on
this valve did not authorize
removal of PS-5.
The inspector
informed the equipment operator
who was performing the surveillance
and the Shift Manager,
who indicated that mechanical
maintenance
would restore
PS-5 to its proper configuration.
'On October 2, the inspector revisited the
licensee's
action,
and noted that the hex nuts for restraint
PS-5
were loose.
The inspector .informed the Plant Manager of the
findings of September
26 and October
2, at the resident
!inspectors'eekly
exit meeting
on October 3,
1991.
On October
9,
1991, the inspector
again
checked
restraint
PS-5
and noted that the hex nuts for this restraint
were
still loose.
The inspector then checked
the
PS-5 restraint
on the=.
"B" CAC skid for a possible generic problem.
Although the
inspector
noted that the hex nuts
on PS-5 of the "B" train of CAC
were tight, the rest'raint configuration was different from PS-5
on
the "A" train.
PS-5 for CAC "A" was configured such that two hex
nuts straddled
the restraint
bar (and were loose)
on one side of
the restraint's
"U-bolt", with the other side of the U-bolt
having'nly
one hex nut.
However, the configuration for PS-5
on the "B"
of two hex nuts outside of the restraint
bar on
each side of the U-bolt (hereafter referred to as
a lock nut and
jam nut configuration).
The inspector obtained the licensee's
vendor drawing CVI-4-1371-
18.20 to determine
the proper method for the PS-5 restraint
configuration.
The drawing revealed that the lock nut and jam nut
configuration
was proper,
leading the inspector
to conclude that
PS-5
on the "A" train was
made
up improperly.
Since this vendor
drawing also
showed the configuration for other restraints
on the
two trains of"CAC, the inspector
inspected
a sample of 20 of the
76
pipe restraints to determine
whether
any additional deficiencies
existed.
Besides
the problem with PS-5,'the
inspector
noted the
following additional discrepancies:
CAC "A" Train Skid:
PS-3
PS-15
PS-18
Missing one jam nut, other nuts straddling
support
Hissing both jam nuts
All nuts loose
CAC "B" Train Skid:
PS-11
Missing both jam nuts
PS-15
PS-18
Missing both jam nuts
Hissing
one jam nut
The inspector notified the Plant Manager of these deficiencies
on October
10,
1991,
and. the Plant Manager directed
a
100%%d
verification of the pipe supports for both
During the
licensee's
walkdown of these
supports,
the following additional
deviations
from the vendor drawing were noted:
f
II
)
)
CAC "A" Train Skid:
PS-10
PS-12
Hissing
3 of 4 nuts, U-bolt, held ih place
by
the only remaining nut
All nuts loose
PS-10
PS-14
All 4 nuts missing, U-bolt in place
Hissing one lock nut, all other nuts loose
PS-20
Two nuts loose
PS-22
PS-23
PS-35
~ Hissing bothjam nuts, lock nuts staked
in
place
Hissing one jam nut, other nuts tight
Excessive
gap between U-bolt and pipe
(3/16 inch vice allowable 1/16 inch)
PS-38
Two nuts loose
The licensee
issued
Problem Evaluation
Request
(PER)
291-841
on
October
11,
1991 to address
issues
associated
with the
supports.
It was the licensee's
position that the
CAC system
was
still operable
and seismically qualified,
based
on engineering
judgement,
because
sufficient rigidity of the system piping
apparently still existed.
However, the above deficiencies
taken
together
appear to violate
10 CFR 50, Appendix B, Criterion V,
"Instructions,
Procedures,
and Drawings" (397/91-44-01).
It is important to note that,
according to knowledgeable
licensee
representatives,
the method
used to seismically qualify the
was to place
each
on
a shaker table
and subject it to
a safe
shutdown
(SSE).
Since they were not qualified by
analysis,
there are
no calculations
which support the seismic
qualification.
The loose, missing, or improperly configured pipe
supports
depicted
above therefore- appeared
to place the seismic
qualification of the
CAC skids (at the time of the inspector's
observations)
in question.
The licensee
corrected
the identified
discrepancies
on October
11,
1991.
b.
Technical Specification 4.6.6. I.b.4 states
that the
CAC system
shall
be demonstrated
at least
every
18 months
by
"verifying through
a visual examination that there is no evidence
of abnormal
conditions within the recombiner enclosure; i.e., loose
wiring or structural
connections,
deposits of foreign materials,
etc."
The licensee
interpreted this visual examination to apply to
each of the
However,
a specific procedure
or checklist
for performing this visual examination did not exist at the time of
0
0
l;
C.
this inspection.
The licensee
performs this inspection
as
a single
step at the completion of the required
18 month
CAC functional
test.
This single procedural
step did not provide any:specific
direction
on how to perform this examination; it merely repeated
verbatim the words of the Technical Specification
quoted
above.
Specific guidance
also
had not been provided for the performance of
system
walkdowns
by the system engineer.
The inspector
noted that
this
TS is unique in specifically requiring
a periodic walkdown of
-the
CAC system,
and concluded that improved guidance
on its
implementation
was needed.
Vendor drawing CVI-4-1371-18.20 provided
no torquing specification
for the pipe support nuts.
Since
a number of these
nuts were found
to be loose or missing,
the inspector requested
more information
concerning
the torquing requirements
the licensee utilizes in this
application.
The inspector will review this information during
a
future inspection
(Followup Item 397/91-44-02).
On October 21,
1991 the inspector verified that the licensee
had
restored
the
CAC pipe restraints
to the correct configurations
in
accordance
with the vendor drawing.
However, during this walkdown,
the inspector identified an additional deficiency.
The inspector
found
a conduit plug for CAC-PT-1A (a pressure
transmitter for CAC
fan
1A) on the floor, and discovered that another plug was loose
on
that
same pressure
transmitter.
An opening in the side of the
pressure
transmitter,
with electrical
leads visible inside,
was
apparently
where the plug on the floor belonged.
This was brought
to the attention-of the electrical
maintenance
engineering staff,
who initiated prompt corrective action to fix the apparent
problem.
The pressure transmitter
was later determined to be subject to
environmental qualification requirements.
However, the system
engineer stated that the 572-foot elevation of the reactor building
(where the
CAC skids are located) is not susceptible
to
a high
energy line break,
as other parts of the reactor building are.
The
are only qualified for a warm, moist environ-
ment; thus,
he preliminarily indicated that the environmental
qualification of CAC-PT-1A would not have
been affected
by the
missing
and loose plugs discussed
above.
According to Technical
Memorandum
(TH) 2004,
Revision 0, electrical
and instrumentation
equipment for the
have bottom entry
conduit,
which precludes
condensation
in the conduit from draining
into a component
and potentially resulting in failure or loss of
accuracy.
TM-2004 does not address
the case
wherein
an instrument
such
as the pressure
transmitter described
above is exposed
to the
secondary
containment
environment at one side.
The inspector
therefore
concluded that the environmental qualification of this
configuration
was indeterminate
(Unresolved
Item 397/91-44-03).
The above findings, taken
as
a whole, further demonstrate
a persistent
weakness
in the proper attention to,
and configuration control 'of,
an
important safety-related
system.
The licensee
also missed opportunities
'k
t
to identify the above deficiencies
on their own by not providing more
complete
guidance
on the implementation of TS surveillance
requirement
4.6.6. l.b.4,
as discussed
above.
5.
Recent
Licensee
Event
Re orts
LERs
Associated with the
CAk S stem
a 0
LER 91-25 - "A" Train of the
CAC S stem Rendered
Ino erable
Lon er
Than Allowed b
the Technical
S ecifications
TS
Due to Loss of
Oil in K dro en Recombiner
Blower
On September
3,
1991,
the
CAC functional test for train "A" was
initiated.
The
CAC blower tripped approximately six seconds
after
receiving
an auto-start
signal
(there is
a six-second
time delay
for the low flow trip signal to allow the blower to establish
an
adequate
flow rate).
The blower motor was found to be drawing
excessive
current, indicating
a locked rotor condition.
An oil
drain plug in the bottom of the blower housing
was found completely
removed
and lying at the bottom of the steel
enclosure
around the
motor/blower assembly.
This had caused
the lubricating oil to
drain from the blower housing.
Upon uncoupling the motor from the
blower, the motor was found to rotate freely, but the blower was
seized.
Disassembly of the blower revealed
severe
bearing
damage.
The immediate six-second
time delay trip, coupled with the bearing
damage,
indicated that the blower was already in a locked rotor
condition when the functional test
was initiated on September
3.
This,led the licensee
to conclude that the bearing
damage
must have
occurred the'ast
time the blower was operated.
This was deter-
mined to have
been during
a surveillance test
on December
8,
1990.
Thus, the "A" train of CAC had
been
since that time.
This meant that
WNP-2 had operated for over four months in Node
1
with the "A" train of CAC inoperable
and the appropriate
action
statement
of the
TS not carried out.
This is an apparent violation
'of the TS, Section 3.6.6. 1,
as stated
in TS 3.0.2 (397/91-44-04}.
The action statement
for TS 3.6.6.
1 requires that
an inoperable
train be restored
to an operable
status within 30 days or that. the
reactor
be placed in Hot Shutdown within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The licensee
speculated
that the oil drain plug fell out due to
vibration from the blower while it was operating.
The oil had
been
replaced
during the
1990 annual refueling outage,
but inadequate
maintenance
instructions
had
been provided,
in that
no torquing
requirements
had
been
speci fied for reinstallation of the drain
plugs.
.The blower,was operated for about eight hours
on December
8
and the licensee
speculates
that it was during that time period
that the drain plug fell out.
Lockwires were installed
on all
blower drain plugs,
both'"A" and
"B" trains,
in September
1991.
Maintenance
procedures
were
enhanced
to require the drain plugs in
each
blower to be torqued,
lockwired,
and verified.
The
LER stated
that the
1990 refueling outage
was the first time the "A" train
blower/motor assembly
had
been
removed since startup
~
The "B"
blower/motor assembly
had not been
removed prior to September
1991.
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The licensee
did not adequately
explain in the
LER how this bearing
damage
escaped
detection during the surveillance test 'conducted
on
December
8.
Further,
had the licensee
implemented
a periodic rota-
tion of the blower as
recommended
by the vendor (paragraph 3.a),
this failure of the blower would have
been discovered kch sooner,
perhaps
in time to comply with the action statement
requirements.
This is especially important, given that normal
system configur-
ation
(as discussed
in paragraph
2 above)
does not allow easy
detection of a low bearing oil level condition.
Although there
are
sightglasses
associated
with both the blower and motor, they are
contained within the steel
enclosure
vessel.
This enclosure
forms
a part of primary containment
and cannot
be opened during plant
operation,
severely limiting the licensee's ability to verify
adequate
lubrication.
Failure of the "A" train
CAC in this manner is another
example of
poor maintenance
of,
and insufficient attention to, the material
condition of an important safety related
system.
As noted above,
the licensee
missed
an opportunity to identify this failure in a
timely manner
by not implementing
a preventive maintenance
action
(periodic rotation of the
CAC blowers)
recommended
by the vendor.
LER 91-29
Inade uate
Primar
Containment
H dro en Recombiner
Rec cle Flow Control
A problem dealing with the recycle flow in each
discovered
by
a contract engineer during the licensee's
setpoint
evaluation
program.
Recycle flow, as discussed
in paragraph
2, is
used to control the rate of hydrogen recombination in the catalytic
recombiner.
It is controlled by varying the position of flow con-
trol valves
(FCV).
Valves
CAC-FCV-6A and
6B serve this function.
By further opening
CAC-FCV-6A or 6B, more flow is passed
through
the recycle line back to'he, blower suction, further diluting the .
stream
from the drywell and decreasing
the rate of hydro-
gen recombination'.
Conversely,
further closing
CAC-FCV-6A or 6B
.
results
in less recycle flow to the blower suction, resulting
im
less dilution of the hydrogen
stream from the drywell and
increasing
the rate of hydrogen recombination.
CAC valve
FCV-6A (Train
B is identical) is controlled
by
a locally
mounted flow indicating controller,
CAC-FIC-67A, which receives
a
signal of actual
recycle flow from flow transmitter
CAC-FT-7A.
CAC-FIC-67A was designed
to be controlled by Haster Controller
CAC-FC-67A, located in the control
room.
CAC-FC-67A receives
input
on total recombiner discharge
flow from CAC-FT-6A and provides
a
setpoint signal, in the automatic
mode, to CAC-FIC-67A.
To operate
properly,
CAC-FC-67A must also
be able to ratio the flow
sensed
in the recycle line (CAC-FT-7A) to the total recombiner
discharge
flow, which is sensed
in the recombiner discharge line
(by CAC-FT-6A).
However, the type of controllers installed
are not
ratio type controllers,
but are proportional-integral
controllers,
'nd
do not receive
an input from actual
recycle flow (CAC-FT-7A).
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Since they are not capable of ratio type control, their output will
either integrate
up or down until the recycle valves
are either
fully open or fully closed.
Consequently,
when 'in automatic,
the
recombiner would have, either tripped
on high exit temperature
(because
of too little recycle flow, if containment
hyh ogen con-
centration
was greater than about
5X) or failed to effectively
remove
(because
of too much recycle flow),'llowing
hydrogen concentration
in the primary containment to increase
to
a
potentially flammable mixture.
It should
be noted that
PPM 2.3.3A and
PPM 2.3.3B required
CAC-FC-
67A and
67B to be in the automatic
mode for post-LOCA operation.
This would have required the operator to correctly diagnose
improper operation of the
CAC system
and then place the controllers
in the manual
mode.
It appeared
to the inspector that operation of
the
CAC system in this manner could have presented difficulty to
the operators,
particularly since existing procedures
did not
provide guidance
on manual
operation of the system.
As stated
in
the
LER,
PPMs 2.3.3A and 2.3.3B were revised
(on August 29,
1991)
to require operation of CAC with CAC-FC-67A/B in the manual
Mode.
This
LER noted that the design discrepancy
being reported
had
existed
since plant construction
and startup.
Records
indicated
that
a Startup
Problem Report
(SPR)
was written in 1981 to document
that the wrong type of controller was supplied for use with the
This discrepancy
was dispositioned
and tracked
by a Project
Engineering Directive
(PED) in 1982
and the applicable
SPR was
closed out.
The
PED directed that
new ratio controllers
be
procured
and installed
as designed.
A memorandum
from Bechtel to
their electrical contractor directed that the work be accomplished
per the
PED.
However, the work was never
accomplished
and .there
are
no records indicating that the
new controllers were ever
procured.
Failure of the licensee's
tracking systems
to ensure
implementation of the
PED was still being researched
by the licen-
see at the conclusion of the inspection.
It appears,
therefore,
that these controllers
have
been
unable to perform their intended
function since plant startup,
and consequently,
that the
CAC system
has
been inoperable
since the plant was first started
up in 1984.
This is an apparent violation of the TS, Section 3.6.6. 1 (397/91-
44-05).
As previously stated,
the licensee
revised
system
procedures
on August 29,
1991 to provide for manual
system
operation.
A System
Lineup Test
was performed in April 1983
and
a Preopera-
tional Test
was performed in December
1983.
Neither of these tests
identified that the wrong type of controllers
was installed.
The
required
18 month surveillance test of the
CAC system
was also
unable to identify the existence of this controller deficiency.
Another aspect of this
LER is noteworthy.
A safety evaluation
was
performed in November
1991 to allow for manual
operation of
CAC-FC-67A/B. It determined that the
55X recycle flow used
as the
analyzed
flow rate in the
FSAR,
and originally used
as the setpoint
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for CAC-FC-67A and
67B in the
CAC operating procedure,
would
probably have resulted
i'n tripping of the recombiner
due to high
catalyst temperature.
This was because
the blower flow rate during
the preoperational
test was"actually measured
to be 86,SCFH at
atmospheric
pressure
vs. the 65.7
SCFH stated
in the
FEAR.
The
flow-rate would be even higher at elevated
containment'pressures.
As
a result of these findings, the licensee
made additional
changes
to
PPHs 2.3.3A and 2.3.3B to provide for stationing
an additional
operator at the
CAC operating
panel
during post-LOCA conditions.
Finally, the inspector
noted that the controller deficiency was
first discovered
and documented
in a
PER on August 7,
1991,
and
was
addressed
by a procedure revision which was issued
on August 29.
However, the licensee's
reportability assessment
was not completed
until October
31 (at which time
a report was
made pursuant to
and
LER 91-29 was not issued until December
2.
This
extended
period after the controller deficiency was identified
before it was reported to the
NRC is an apparent violation of- the
reporting requirements
of 10 CFR 50.72
and 50.73 (397/91-44-06).
The inspector
concluded that the licensee
had missed opportunities
to discover
and correct this problem with the
CAC flow controllers.
It appeared
that without operator action,
the
CAC system would not
have
been
able to fulfillits intended safety function.
In
addition, operati'ng
procedures
in effect from plant startup until
August 29,
1991 directed the use of the automatic
mode for the
controllers
and provided
no guidance to operators
on how to control
the
CAC system in the manual
mode.
6.
Hiscellaneous
Problem Evaluation
Re uests
Other problems with valves
CAC-FCV-6A and
6B have also
been identified
by the licensee.
Problem Evaluation
Request
(PER)
291-481
documented
a
deficiency in Hay 1991, in that neither valve would achieve its full
1-3/8" stroke.
Valve FCV-6A would only stroke 1".
Also, the valve was
80X closed
when
a 50X signal
(12 milliamps) was applied to it, vs. the
50% closed that it should
have
been.
Likewise,
FCV-6B would only stroke
1-1/8" and reached
80X closed
when
a 50X closed signal
was applied to
it.
These conditions
were significant, in that they would have affected
the ability of the
CAC system to achieve the proper recycle flow, and
therefore to avoid system
shutdown
on high catalyst temperature.
These
conditions
were corrected
before the end of the
1991 refueling outage,
and were determined
by the licensee
not to have affected
system opera-
bility.
7.
Conclusions
Apparent violations of regulatory requirements
were identified during
this inspection,
as discussed
in the foregoing paragraphs.
These
are
summarized
as follows:
Seismic supports for the
CAC system were not assembled
as required
(paragraph
4.a).
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The "A" Train of the
CAC system
was inoperable
from December
1990
through September
1991
because
of loss of lubricating .oil from the
blower (paragraph
5.a).
Both trains of the
CAC system were inoperable
from before initial
plant startup, until procedures
were revised in August '1991 to
provide'for manual
operation,
because
improper recycle flow
controllers
were installed
(paragraph
5.b).
The licensee
did not report the inoperability of both trains of CAC
(caused
by the use of improper flow controllers) within the time
periods required
by 10 CFR 50.72
and 50.73
(paragraph 5.b).
The
NRC expects
safety
systems to be operable
in accordance
with the
Technical Specifications,
configured in accordance
with design drawings
and the Final Safety Analysis Report,
operated with correct procedures,
and maintained
in a manner which provides
a high degree of confidence
that the system will perform its intended safety function when called
upon.
The above apparent violations
and other inspection findings
discussed
earl'ier in this report indicate that this requisite attention
to the
CAC system
by Supply System
management
has not been provided.
It
appears
that the involvement of the engineering,
quality assurance,
operations,
and maintenance
organizations
in the
CAC system
has
been
insufficient.
8.
Unresolved
Item
Unresolved
stems
are matters
about which the
NRC requires further infor-
mation in order to determine
whether the matters
represent
violations,
deviations,
or acceptable
items.
An unresolved
item identified during
this inspection is 'discussed
in paragraph
4.c of this report.
9.
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An exit meeting
was conducted with the indicated licensee
personnel
(refer to paragraph
1)
on December
6,
1991.
The scope of this
inspection
and the inspectors'indings,
as noted in this report,
were
discussed
and acknowledged'by
the licensee
representatives.
The licensee
did not identify as proprietary
any of the information
reviewed
by or discussed
with the inspectors
during the inspection.
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