ML17312B414
| ML17312B414 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/01/1997 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML17312B412 | List: |
| References | |
| 50-528-97-09, 50-528-97-9, 50-529-97-09, 50-529-97-9, 50-530-97-09, 50-530-97-9, NUDOCS 9705070087 | |
| Download: ML17312B414 (44) | |
See also: IR 05000528/1997009
Text
ENCLOSURE 2
U.S. NUCLEAR REGULATORY COMMISSION
REGION IV
Docket Nos.:
License Nos.:
Report No.:
Licensee:
Facility:
Location:
Dates:
Inspectors:
50-528; 50-529; 50-530
50-528;-529;-530/97-09
Arizona Public Service Company
Palo Verde Nuclear Generating Station, Units 1, 2, and 3
5951 S. Wintersburg Road
Tonopah, Arizona
March 11-21, 1997, with inoffice inspection continuing until April 4,
1997
Lawrence
E. Ellershaw, Reactor Inspector, Maintenance
Branch
Division of Reactor Safety
e
Approved By:
Attachment:
Daniel R. Carter, Resident Inspector, Project Branch F
Division of Reactor Projects
Dr, Dale A. Powers, Chief, Maintenance
Branch
Division of Reactor Safety
Supplemental
Information
.
9705070087
97050k
ADOCK 05000528
G
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EXECUTIVE SUMMARY
Palo Verde Nuclear Generating Station, Units 1, 2, and 3
NRC Inspection Report 50-528/97-09; 50-529/97-09; 50-530/97-09
This special inspection was performed to assess
the circumstances
surrounding the
inadvertent drain down of the Unit 3 spent fuel pool ~
The report covers
a 4-week period of
announced
inspection by a region-based
inspector and the resident inspector.
~Oerations
A violation regarding
a failure to comply with a procedure,
in conjunction with poor
work planning (i.e., not having required equipment available to perform the
designated
task), resulted in the installation of incorrect equipment.
In addition, a
violation of work controls was identified, when operations personnel performed
undocumented
work prescribed
by a maintenance
procedure,
which resulted in a
loss of configuration control over the pressurization
supply for the spent fuel pool
gate seals.
There was a lack of communication and coordination between the
maintenance
and operations departments
(Section 01.1).
e
The shift supervisor and operations staff performed well in taking appropriate
and
timely actions to identify and correct the immediate causes of the spent fuel pool
inadvertent drain down (Section 01.1).
The licensee's investigative report of the inadvertent partial drain down of the spent
fuel pool was very thorough, comprehensive,
and objective (Section 01.1).
~
A violation was identified by the inspectors when it was determined that
valve PCE-V125 was unlocked and its status was not properly documented
in the
record book.
The applicable procedure
lacked the specificity required to
preclude confusion regarding the circumstances
as to when a valve should be
locked in its required position (Section 08.1).
Maintenance
~
The inspectors identified a violation regarding preventive maintenance
requirements
applicable to the spent fuel pool gate seals.
The initial preventive maintenance
requirements
(in effect through December 1994) included replacement of the spent
fuel pool gate seals every 4 years.
However, certain gate seals have never been
replaced,
and others were not replaced within the established
4-year replacement
frequency (Section E.8.1).
-3-
~
The inspectors identified a violation pertaining to inadequacies
of inspection criteria
used to determine whether a gate seal required replacement.
The applicable
procedure failed to prescribe specific inspection technique or methodology, the
necessary
inspection conditions (i.e., lighting, aided or unaided visual with respect
to magnification, and scope or area of the seal to be inspected),
the
training/qualifications of the personnel who perform the inspection, and what
constitutes acceptance
criteria (Section E.8.1).
~En ineerin
The safety-related
spent fuel pool transfer canal gate seal had never been provided
with an alarm to detect or provide abnormal pressure
conditions, nor had any
provisions been established for conducting periodic monitoring of gate seal pressure
(Section E8.1).
The inspectors identified a long-term design control violation regarding
a failure to
establish provisions for assuring that the safety-related function of the spent fuel
pool gate seals would not be lost (Section E8.1).
The licensee had performed
a design bases validation of gate seal design which
resulted in the development of a prudent and conservative modification to eliminate
the need for the decontamination
pit gate seal by welding the gate shut in each unit
(Section E8.1)
~
The licensee conservatively set new design bases criteria for spent fuel pool and
cask loading pit water levels so that a failure of both the cask loading pit and fuel
transfer canal gate seals would not result in the spent fuel pool cooling water
pumps losing suction during a design basis accident.
It also ensured that with a
failure of'the cask loading pit gate seal, the maximum dilution of the spent fuel pool
would not decrease
spent fuel pool boron concentration below the Technical
Specification minimum level (Section E8.2).
The licensee's evaluation of Generic Letter 88-14 did not appear to consider the
safety-related
spent fuel pool gate seals, which resulted in a missed opportunity to
assure that the seals would continue to perform their safety-related function upon
loss-of-instrument
air (Section E8.3).
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Re ort Details
Summar
of Plant Status
During the onsite inspection period, Units
1 and 2 were at power operations while Unit 3
was in Refueling Outage 3R6.
I. 0 erations
01
Conduct of Operations
01.1
Inadvertent Draindown of the S ent Fuel Pool
Unit 3
On March 6, 1997, the Unit 3 control room received
a fuel pool cooling system
trouble alarm.
The fuel pool level hi-lo annunciator
on the local alarm panel
was found to be in alarm.
The normal level of the spent fuel pool was 138 feet,
while the low level alarm setpoint was 137 feet 6 inches.
The observed
spent
fuel pool level was found to be 137 feet 5 inches.
Abnormal Operating
Procedure 43AO-3ZZ53, "Loss of Refueling Pool and/or Spent Fuel Pool Level," was
entered
as required by the alarm response
procedure.
Non-essential
personnel were
evacuated
from the fuel building and the fuel building essential ventilation system
was manually actuated.
The Fuel Building Essential Exhaust Fan A supply damper
failed to open and Fuel Building Essential Exhaust Fan A did not start.
The damper
was manually opened
and the fan started.
The spent fuel pool level was restored to
normal level. A notice of unusual event was declared based on an uncontrolled
water level decrease
in the spent fuel pool, and terminated upon restoration of
normal level.
a.
Ins ection Sco
e
92901
The inspectors reviewed the circumstances
surrounding this event to determine if
the licensee had taken appropriate actions to identify the cause and establish
corrective actions to prevent recurrence.
b.
Observations
and Findin s
b.1
Back round
The Palo Verde Nuclear Generating Station fuel pools were designed with three
gates.
Two of these gates (fuel transfer canal and the cask loading pit) were
equipped with single bladder pneumatic seals.
The instrument air system is the
normal source of air for these seals.
In the event the instrument air system fails,
-5-
the plant service gas system
is to provide automatic backup service (compressed
nitrogen).
As discussed
in Section E.8.1 below, the gate between the cask loading
pit and the cask decontamination
pit was modified (gate welded in place) to
eliminate any leakage of spent fuel pool cooling water past the spent fuel pool/cask
loading pit boundary.
Up until early 1993, temporary nitrogen bottles were installed as a backup gas
supply through the use of temporary modification requests,
each of which
underwent the 10 CFR 50.59 screening
and evaluation process.
In an effort to
reduce the number of temporary modifications, the licensee determined that the
backup gas installation process should be proceduralized.
This was accomplished
with the development of Maintenance Test Procedure 31MT-9IA01, "Installation
and Removal of Temporary Air/Nitrogen Supply for Fuel Transfer Canal Gate,"
which received
a 10 CFR 50.59 screening
and evaluation dated February 25, 1993.
In conjunction with this effort, Engineering
Evaluation Request
EER 93-IA-001 was
initiated in order to establish specific hardware/equipment
requirements
in the new
procedure.
The engineering
evaluation request stated that substitutions
on some of
the tubing fittings were allowed as long as a minimum flow diameter was
maintained.
It also stated that the nitrogen cylinder, regulator valve, and pressure
relief valve were sized so that the pressure
relief valve would release any excess
flow should the regulator fail, thereby, precluding overpressurization
and bursting of
the seal.
It further required that the procedure
be changed to specify the equipment
selected
in the engineering
evaluation request,
and that there was to be no
substitution of these valves or the nitrogen cylinder without prior engineering
approval.
The hardware/equipment
selections
and material substitution comments were
incorporated into Procedure 31MT-9IA01 as "Appendix A - Temporary Back-Up
Assembly - Parts List." This revision included a description of the nitrogen cylinder,
which stated: .Stock Code 27, 2500 psig, and 330-cubic foot volume capacity.
b.2
Event Descri tion
On February 23, 1997, Unit 3 was in Refueling Outage 3R6.
Before flooding up the
containment refueling cavity and removing the fuel transfer tube blind flange, a
backup nitrogen gas supply to the spent fuel pool transfer canal gate seal was
required to be installed.
The installation was also required each time the instrument
air system was taken out of service.
Work Order 00756589, "Installation and Removal of Temporary Air/Nitrogen Supply
for Fuel Transfer Canal Gate," was released
and assigned to the refueling and
mechanical support group on February 23, 1997.
For implementation purposes,
the
work order was attached
(became a'cover sheet) to Procedure 31MT-9IA01,
Revision 2. The refueling and mechanical support team leader was told by
warehouse
personnel that the nitrogen cylinder (Stock Code 27) required by the
procedure was not in stock,
-6-
The refueling and mechanical support team leader tasked his crew to search
the gas cylinder storage areas of each unit for the proper cylinder.
No cylinder
of that size/designation
was found; however, the heating, ventilation, and air
conditioning group had a smaller nitrogen cylinder (40-50 cubic foot, 1800 psig)
that was available.
Even though the maintenance
procedure stated, "No
substitutions without prior Engineering approval," the refueling and mechanical
support team leader (an engineer) made the decision to install the smaller cylinder,
completed Step 4.1.8 of the maintenance test procedure showing that the backup
nitrogen gas supply was installed (but not in service), and notified outage central.
During subsequent
discussion with the inspectors, the refueling and mechanical
support team leader stated that he considered
himself qualified to make that
decision based
on his engineering background,
training, and knowledge regarding
previous outages.
The inspectors observed,
however, that neither the basis for his
decision nor the cylinder substitution were documented
or noted in the maintenance
procedure,
and the shift supervisor was not informed of the substitution.
Technical Specification 6.8 requires written procedures to be established
and
implemented for various activities, including refueling operations.
The failure to
comply with Procedure 31MT-9IA01 resulted in a condition different from what was
required and expected
by Engineering Evaluation Request
EER 93-IA-001. The
inspectors considered this a failure to comply with Pr'ocedure 31MT-9IA01, which
constituted
a violation of Technical Specification 6.8 (50-528;-529;-530/9709-01).
Concurrent with his decision to install the smaller cylinder, the refueling and
mechanical support team leader ordered the correct size nitrogen cylinder and was
told it would be delivered approximately February 25, 1997.
On February 25, the
refueling and mechanical support team leader was informed that the ordered
nitrogen cylinder was delivered to the 140-foot level of the fuel building; however,
no action was taken to replace the previously installed smaller cylinder with the
correct size cylinder.
The instrument air system, which provided the normal air supply to the spent fuel
pool gate seals, had been scheduled for a planned outage of approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />
to replace some gaskets.
This also required isolation of the plant service gas
(nitrogen) system.
Procedure
31MT-9IA01 contained
a cautionary note that stated,
"Steps 4.1.9 through 4.1.12 are to be performed only if the instrument air system
is lost or taken out of service.
Maintenance'will be notified by Outage Central or
the Shift Supervisor to proceed."
Steps 4.1.9 through 4.1.12 described the actions
to place the backup nitrogen cylinder in service and.isolate instrument air from the
transfer canal gate seal
~
On March 4, 1997, between
3 and 4:25 a.m., operations
personnel attempted to
place the temporary backup nitrogen cylinder in service.
However, there was a leak
at the regulator-to-cylinder connection.
Operations personnel
called refueling and
mechanical support and requested
assistance
to repair the leak.
The refueling and
mechanical support personnel went to the backup cylinder location, tightened the
I
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I
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I
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leaking fitting, and performed
a leak check to verify that no additional leaks existed.
The inspectors
noted that Step 4.1.11
in Procedure
31MT-9IA01 required the
performance of a leak check on all the applicable connections;
however, no leak
test method was specified.
The inspectors discussed
this activity with the involved
mechanics to determine how leak testing was performed.
The mechanics
said that
it was left up to their discretion as to how they checked for leaks.
In this case,
they said that they used their physical senses
(i.e., hearing and touch).
They also
informed the inspectors that it appeared
operations personnel
had used the
maintenance
procedure to place the backup nitrogen cylinder in service.
The inspectors determined that on March 4, 1997, at 3:13 a.m., clearance tag
placement was authorized
and at 4:25 a.m. the instrument air outage was initiated.
At 8:30 a.m. instrument air work commenced
and was completed at 11:25 a.m.
Clearance tags were removed at 1:05 p.m. and the instrument air outage was
completed at 4 p.m.
However, the required verification signoff (Step 4.1.14)
showing completion and'acceptance
of these activities was not performed by
operations
personnel.
Since the step had not been signed off, refueling and
mechanical support personnel were unaware that the next sequence
of steps (i.e.,
Steps 4.2.1 through 4.2.8 - removal of backup nitrogen and restoration of
instrument air to the transfer canal gate seal) needed to be performed.
This
oversight, including the failure to document work performance,
resulted in an
unclear operational status of the instrument air system and contributed to the
subsequent
inadvertent drain down of the spent fuel pool.
Section 3.7 in Procedure
30DP-9MP01, "Conduct of Maintenance,"
Revision 21,
required maintenance
work instructions to be documented
and statused,
including
final acceptance
and signoffs of verification steps.
Verification Step 4.1.14 in the
working copy of Procedure 31MT-9IA01 was not signed off by operations personnel
subsequent
to the completion of the previous work steps.
The inspectors
considered this a failure to document and status work performance
as required by
Procedure 31MT-91A01 and constituted
a second example of a violation of
Technical Specification 6.8 (50-528;-529;-530/9709-01).
On March 6, 1997, the core had been fully off loaded to the spent fuel pool.
The
reactor coolant system was at the half pipe level of the cold leg (i.e., licensee
description of mid-loop reactor coolant system operation with no fuel in the reactor
vessel) and the spent fuel pool level had been controlled at approximately 138 feet
2 inches.
At 6:25 a.m., the control room received
a fuel pool cooling system
trouble alarm.
Since this alarm can be actuated by a number of different inputs, the
alarm response
procedure
required sending
an operator to the fuel building local
panel to determine the reason for the alarm.
The fuel pool level hi-lo annunciator on
the local alarm panel was found to be in alarm.
The low level alarm setpoint
was 137 feet 6 inches, arid the observed
spent fuel pool level was found by the
auxiliary operator to be 137 feet 5 inches.
The control room dispatched
auxiliary
operators to determine the cause of the decreasing
level. Abnormal Operating
Procedure 43AO-3ZZ53, "Loss of Refueling Pool and/or Spent Fuel Pool Level,"
-8-
Revision 3, was entered
as required by the alarm response
procedure.
At
approximately 6:43 a.m., non-essential
personnel were evacuated
from the fuel
building and the fuel building essential ventilation system was manually
activated.
Fuel Building Essential Exhaust Fan A supply damper failed to open
and Fuel Building Essential Exhaust Fan A did not start.
The damper was manually
opened from the control room and the fan started.
At 6:45 a.m., the shift
supervisor left the control room to assist with determining the source of the
spent fuel pool water loss.
At 6:47 a.m., a boric acid makeup pump was started
to provide approximately 165 gpm makeup to the spent fuel pool. At approximately
7:05 a.m., the shift supervisor 'discovered:
(1) the fuel transfer canal gate seal
pressure was at 5 psig; (2) the backup nitrogen bottle, which was still in service,
was depleted
and indicated 0 psig; and (3) instrument air to the gate seal remained
isolated.
The shift supervisor initiated action to isolate the backup nitrogen bottle,
restore instrument air to the gate seal, and refill the spent fuel pool. At
approximately 7:10 a.m., with the transfer canal gate seal pressure
restored, the
spent fuel pool level started to rise to the normal level.
At 7:15 a.m., the shift supervisor declared
a notice of unusual event based on an
uncontrolled water level decrease
from the spent fuel pool, which was terminated
with the restoration of normal spent fuel pool water level. At 8:02 a.m., the boric
acid makeup pump was secured with spent fuel pool level re-established
at
138 feet.
The licensee initiated Condition Report/Disposition Request 3-7-0116 on March 6,
1997, with a recommendation to perform. an evaluation of the event to determine
the root cause.
The licensee assembled
an investigative team to conduct a
significant root cause investigation, which was performed, essentially,
in parallel
with this inspection.
The inspectors were informed that the expected date for
issuance of a final report detailing the investigative effort and conclusions was
March 19, 1997.
The completed investigative report, however, did not receive final
licensee management
approval until March 25, and was subsequently
received on
March 28, 1997.
The report identified the root cause of the event to be insufficient
technical rigor, follow through, and operational controls applied in the development
of the temporary nitrogen backup supply to the spent fuel pool transfer canal gate
seal.
The report also identified the need for 18 corrective actions associated
with
this event
(1 of which had been completed).
Of the remaining 17 corrective
actions, 16 are due to be completed by October 1, 1997, and
1 (provide a site-wide
video briefing emphasizing
spent fuel pool design and activities) was to be shown
prior to each unit's next scheduled
refueling outage.
Conclusions
The shift supervisor
and operations'staff performed well in taking appropriate
and
timely actions to identify and correct the immediate causes of the inadvertent partial
draind own.
I
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A violation regarding
a failure to comply with a procedure,
in conjunction with poor
work planning (Le., not having required equipment available to perform the
designated
task), resulted in the installation of equipment different from that
specified.
In addition,
a violation of work controls was identified when operations
personnel performed undocumented
work prescribed
by a maintenance
procedure,
which resulted in a loss of configuration control over the pressurization
supply for
the spent fuel pool gate seals.
The spent fuel pool partial drain down event could
have been precluded
had there not been
a lack of communication
and coordination
between the maintenance
and operations departments.
The licensee's investigative report of the inadvertent partial drain down of the spent
fuel pool was very thorough, comprehensive,
and objective.
08
miscellaneous
Operations Issues
08.1
Im lementation of Locked Valve Pro ram
a 0
Sco
e 92901
The inspectors identified and reviewed the possible drain paths from the spent fuel
pool, the transfer canal, and the cask loading pit, to determine if administrative
controls were adequate,
and to verify that affected components
were properly
positioned and controlled.
Observations
and Findin s
On March 13, 1997, during review of the "Locked Valve, Breaker, and Component
Record Book," used to provide component status, the inspectors noted that fuel
canal drain isolation to Cleanup Header Valve PCE-V125 was shown to be open.
The record book showed that on February 20, 1997, valve PCE-V125 was opened
in accordance
with Procedure 40OP-9PC06,
"Fuel Pool Cleanup and Transfer,"
Revision 2, to drain the spent fuel pool transfer canal.
The record book showed
that the other spent fuel pool transfer canal drain valve and both drain valves to the
cask. loading pit were closed and locked.
Administrative Control Procedure 40AC-OZZ06. "Locked Valve, Breaker, and
Component Control," Revision 11, provided the requirements to assure
that components,
identified as having locking provisions, were properly
controlled and locked.
Departmental Procedure 40DP-9OP19, "Locked Valve,
Breaker, 'and Component Tracking," Revision 39, implemented the requirements'of
Procedure 40AC-OZZ06 by providing administrative controls and means for
documenting
changes to valve positions.
Appendix,A to Procedure 40DP-9OP19
stated that the basis or justification for valve PCE-V125 to be locked closed, was to
prevent an inadvertent drainage of the fuel transfer canal during refueling.
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While refueling operations were underway on March 13, 1997, the inspectors went
to the valves and observed the valve positions.
With the exception of
valve PCE-V125, the other three drain valves were in a closed and locked position.
Valve PCE-V125 was closed, but not locked as required by Procedure
The inspectors discussed
this with the shift supervisor to determine the basis for
the valve not being locked closed.
Licensee personnel were immediately dispatched
to lock the valve and document that it was locked in its closed position.
The inspectors determined,
by review of reactor operator logs, that
valve PCE-V125 had undergone
several manipulations between February 20 and
March 'l3, 1997.
On February 20, 1997, the valve was opened
in accordance
with Procedure
40OP-9PC06 to drain the spent fuel pool transfer canal.
This entry
was noted in the record book.
On February 22, 1997, Procedure 40OP-9PC06 was
used to transfer water from the spent fuel pool transfer canal.
Upon completion of
the task, Steps 8.3.2 and 8.3.3 required closure and independent
verification that
the valve was closed.
The procedure's
identification of valve PCE-V125 included an
asterisk, which denoted that the valve was controlled by Procedure 40AC-OZZ06.
On March 7, 1997, the spent fuel pool transfer canal was filled with water from the
refueling water tank using Procedure 400P-9PC07,
"Miscellaneous
Fuel Pool
Operations,"
Revision 8. This required opening valve PCE-V125 to align flow from
the refueling water tank to the spent fuel pool.
Upon completion of the refill,
Step 9.3.14 required closure of the valve, and Step 9.3.17 provided an independent
verification.
The inspectors noted that this procedure's
identification of the valve
did not include an asterisk or other means to show that the valve was under the
control of Procedure 40AC-OZZ06.
Procedure
40DP-9OP19 stated in Section 2.0, "Responsibilities," that, "The
CRS/Shift Supervisor
is responsible for: Authorizing the operation of Locked Valves,
Breaker, and Components
and ensuring the valves, breakers,
and co'mponents
are
returned to their required position AND locked as soon as conditions permit."
Further, Section 3.4 states,
"Prior to changing
MODEs the Locked Valves/Breaker/
Component
Record Book shall be reviewed.
Each system shall have Individual
Valves/Breaker/Component
Change
Record reasons
reviewed to determine if it is
necessary
to maintain that valve, breaker, or component out of its locked position."
The inspectors determined that between February 20, and 'March 13, 1997, Unit 3
'went through
a minimum of five mode changes,
without evidence of the record
~ book status of valve PCE-V125 being reviewed or changed to reflect the actual
condition.
On March 12, prior to entering Mode 6, (the start of refueling operations)
the shift supervisor stated he reviewed the locked valve, breaker, and
component record book.
He indicated that the valve was being controlled under
Procedure 40OP-9PC06
and would be locked prior to going into Mode 4, when all
system valve lineups are performed.
e
-1 1-
Based on operator logs, the inspectors determined that valve PCE-V125 remained
unlocked for a total time of 19 days (13 days between February 22 and March 7,
and 6 days between March 7 and March 13).
The valve was also incorrectly
statused
as open in the record book between February 22 and March 13, 1997.
Further, on March 13, 1997, while fuel was being moved, the inspectors observed
valve PCE-V125 in a closed but unlocked position.
These oversights were failures
to meet the requirements
(e.g., lock and properly status) of Administrative Control
Procedure 40AC-OZZ06, and constitute the third example of a violation of Technical Specification 6.8 (50-528;-529;-530/9709-01).
Licensee personnel initiated Condition Report/Disposition Request
CRDR 3-7-0162
on March 13, 1997, to evaluate and determine the adequacy of existing methods
and controls associated
with locking certain components that might undergo several
manipulations during outages.
c.
Conclusions
valve should be locked in its required posi
08.2
Fuel Buildin
Essential Ventilation S stem
A violation was,identified by the inspectors when it was determined that
responsible
personnel
had not locked and properly statused
valve PCE-V125.
The
implementing procedure lacked specificity regarding the circumstances
as to when a
tion.
a e
Sco
e
92901
The inspectors reviewed the circumstances
surrounding the Fuel Building Essential
Exhaust Fan A supply damper failure to open, and the Fuel Building Essential
Exhaust Fan A failure to start.
b.
Observations
and Findin s
Upon detection, of a loss of spent fuel pool water level, Abnormal'Operating
Procedure 43AO-3ZZ53, "Loss of Refueling Pool and/or Spent Fuel Pool Level,"
Revision 3, was entered
as required by the alarm response
procedure.
Non-essential
personnel were evacuated
from the fuel building and the fuel building
essential ventilation system was manually initiated.
Fuel Building Essential Exhaust
Fan A supply damper failed to open and Fuel Building Essential Exhaust Fan A did
not start.
The damper was manually opened
and the fan started.
Licensee personnel identified and replaced
a faulty relay. Testing verified that
replacement of the relay corrected the problem.
The inspectors reviewed corrective
maintenance
records and did not identify any prior failures.
The inspectors also
reviewed surveillance test history of the Train A fuel building essential ventilation air
e
-1 2-
system to determine if the surveillance tests required by Technical Specification
Surveillance Requirement 4.9.12, "Fuel Building Essential Ventilation System," had
been appropriately performed.
The inspectors determined these tests were being
performed as required, with test results meeting the acceptance
criteria of the
Technical Specification.
C.
Conclusions
This inspectors considered this event to be an isolated occurrence that was
promptly corrected.
There were no indications that this type of incident had
occurred previously, and all required surveillance activities appeared
to have been
appropriately performed.
III. En ineerin
E2
Engineering Support of Facilities and Equipment
A recent discovery of a licensee operating their facility in a manner contrary to the
Updated Final Safety Analysis Report description highlighted the need for a special
focused review that compares plant practices, and/or parameters to the Updated
Final Safety Analysis Report description.
While performing the inspections
discussed
in this report, the inspectors reviewed the applicable portions of the
Updated Final Safety Analysis Report that related to the areas inspected.
The inspectors noted two inconsistencies
between the Updated Final Safety
Analysis Report description and actual plant configuration.
The Updated Final
Safety Analysis Report addressed:
(1) the use of a bolted, blind flange at the
containment building end of the transfer canal tube and (2) the use of a
nonpermanent,
inflatable reactor cavity (refueling cavity) seal.
However, the plant
configuration had a quick-disconnect fitting in lieu of the blind flange, and a
permanent,
welded-in-place seal in lieu of the inflatable seal.
Licensee personnel
informed the inspectors that these changes
(and others) had been identified and
included in Licensing Document Change Requests
3613 and 3647, which were
scheduled to be submitted to NRC in December 1997, for inclusion in the Spring
1998 update to the Updated Final Safety Analysis Report.
I
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E8
Miscellaneous Engineering Issues
E8.1
S ent Fuel Pool Pneumatic
Gate Seals
a 0
Ins ection Sco
e 92903
The scope of this inspection effort was to review the spent fuel'pool gate seal
design characteristics,
and the associated
maintenance
and inspection controls to
assure that the intended design functions were being maintained.
b.
Observations
and Findin s
During this inspection, cognizant licensee personnel informed the inspectors that the
gate seals were considered
nonsafety related.
The inspectors determined that this
information was inconsistent with the information identified in the Updated Final
Safety Analysis Report and the applicable drawings.
Chapter 9, "Auxiliary Systems,"
in Revision 8 to the Updated Final Safety Analysis
Report, described the design of equipment for the storage of new and irradiated
fuel, the fuel pools, and other systems/subsystems
used to support storage of fuel.
The Updated Final Safety Analysis Report discussed
the fuel pool gates with respect
to sizing (i.e., large enough to allow passage
of the spent fuel handling machine
with a fuel element attached); however, no separate
discussion on pneumatic gate
seals was found.
Updated Final Safety Analysis Report, Table 3.2-1, "Quality Classification of
Structures, Systems,
and Components,"
identified the spent fuel pool gate
classification as Seismic Category
I and Quality Class Q.
Note 4 of Table 3.2-1
defined Quality Class Q as a quality class that requires compliance with Appendix B
to 10 CFR Part 50 (safety-related
applicability).
The inspectors reviewed Revision 0 to Drawings 13-C174-13 and 13-C174-14,
which were the applicable fuel transfer canal gate seal piping and instrumentation
drawings.
Both drawings were titled, "Spent Fuel Pool Gates-Fuel Transfer Gates,"
and had a Quality Class Q designation.
The drawings also'ndicated
the class break
at the air supply tube and the seal valve stem connecter, with all equipment
downstream of that interface (i.e., connector and seal) being Quality Class Q.
Similarly, Drawing 583-A, "Cask Loading Pit Gate," Revision 3, showed the class
break, with the connector and seal designated
as Quality Class Q.
-14-
The noimal air supply to the fuel transfer canal gate seal was provided by the
instrument air system, which was nonsafety related.
If the instrument air system
was lost or taken out of service, the maintenance
department was directed to place
a backup nitrogen system in service by performing the specified steps contained
in
Procedure 31MT-9IA01. The temporary air/nitrogen supply system was also
considered
nonsafety related, as shown in Engineering Evaluation
,Request
EER 93-IA-001, dated January
15, 1993.
The inspectors noted that the spent fuel pool transfer canal gate seal had never
been provided with an alarm to detect or provide abnormal pressure
conditions, nor
had any provisions been established
for conducting periodic monitoring of gate seal
pressure.
The gate seals were designated
as safety related since the beginning of commercial
operations, yet no provisions were established to assure that their safety-related
function would not be lost.
Measures
did not assure selection and review for
suitability of application of parts or equipment that were essential to the safety-
related function of the gate seals,
in that the gate seal air supply sources
(instrument air system, plant service gas (nitrogen) system, temporary nitrogen
cylinders) and connecting hardware are classified as nonseismic
and nonsafety
related.
This failure to establish appropriate design control measures
for the spent
fuel pool gate seals constituted
a violation of Criterion III of Appendix B to 10 CFR Part 50 (50-528;-529;-530/9709-02).
The licensee performed
a design bases validation which resulted in the issuance of
Condition Report/Disposition
Request
CRDR 95-0326 on April 12, 1995.
The
condition report/disposition
request evaluated deficiencies in gate seal design
associated
with a loss of offsite power and a seismic event.
The licensee
determined that the most limiting condition would be a catastrophic failure of both
the decontamination
pit seal and the cask loading pit seal, which could allow an
uncontrolled spill to the fuel building floor. This resulted in the licensee developing
a conservative modification to eliminate the need for the decontamination
pit gate
seal by welding the gate shut in each unit. Unit 1 was completed during September
1996; Unit 2 was completed during December 1996; and Unit 3 was completed
during February 1997.
The inspectors reviewed the seal design criteria with respect to shelf
life, service life, and maintenance/inspection
requirements.
The seal
manufacturer was The Presray Corporation, and the seal type was identified
as PRS 583, made from a material shown to be EPDM Compound 603 reinforced
with nylon fabric. The purchase
orders to The Presray Corporation imposed
the requirements
of Appendix B to 10 CFR Part 50 and 10 CFR Part 21
~ Licensee
personnel
provided the inspectors with Document 13-C174-21-2, "Guidelines
For Spent Fuel Pool Gate Seals Installation, Test, Operation, And Removal ~"
The document was intended to provide engineering information to assist in
preparation of related procedures.
The document stated that the information
e
-15-
was considered
as guidelines and was nonmandatory.
The document was not
dated, but had a date received stamp of March 14, 1988, and referenced
Bechtel
Power Corporation's Specification 13-CM-174, "Fuel Pool Gates."
The document
provided the following technical data:
seal operating pressure 35-40 psi;
operating temperature
50-125 degrees
F; radiation exposure
5 x 10'ads over
40 years; maximum life of 6 years; and maximum service life of 4 years.
This
became the basis for creating Master Instruction PMM09535 and Preventive
.,Maintenance Task 082288, which specified replacement of gate seals every
4 years.
Licensee personnel
provided the inspectors with a copy of Wyle Laboratories
Engineering
Report 26409, "Analysis of Spent Fuel Pool Gate Seal For Use in Palo
'erde Nuclear Generating Station, Units 1, 2, and 3." This document,
dated
January 31, 1983, was prepared
by Wyle Laboratories for Bechtel Power
Corporation,
and presented
an aging analysis to determine the susceptibility of
the seals to radiation and time/temperature
related mechanisms.
Bechtel Power
Corporation specified that susceptibility be determined solely on the individual
effects of radiation and time/temperature
related mechanisms.
No other
mechanisms
were to be considered.
Bechtel Power Corporation specified the
following conditions be used:
Temperature
125 degrees
F and radiation (40-year
integrated dose) of
1 x 10 Rads'.
The Wyle Laboratories report, based on radiation
resistance testing performed by The Presway'Corporation
and a thermal aging
analysis, concluded that the effects of radiation were insignificant, and the thermal
aging analysis provided a calculated life of greater than 40 years for both EPDM and
the reinforcing nylon using 50 percent loss of elongation and 50 percent loss of
tensile strength, respectively,
as the acceptance
crit'eria.
The inspectors concurred with the Wyle Laboratories engineering report conclusion;
however, upon using the originally defined radiation exposure of 5 x 10'ads, the
radiation effects, while still within the acceptable
radiation resistance
limits, could
no longer be considered insignificant.
By lette'r dated May 25, 1994, a licensee request was submitted to The Presray
Corporation for a relaxation of the service life limitation. The request provided
the specific storage
and usage conditions of the seals, in terms of air/water
temperatures,
measured
radiation exposure rates, and water chemistry.
The
Presray Corporation responded
by letter dated June 2, 1994, which, based
on
identified conditions, granted
a storage life extension from 2 to 5 years.
They also
stated, however, since the cumulative exposure to radiation over 40 years was.5 x
10'ads, they still recommended
a 4-year service life, which would be equivalent
to 5 x 10~ Rads.
On December 9, 1994, an internal memorandum
was issued, in which engineering
recommended
that Preventive Maintenance Task 082288 be revised to reflect an
extended
shelf life of 5 years and elimination of the 4-year service life. The
service life change was based on measured
exposure
dose rates which averaged
e
0
-16-
approximately 200 mRem/hr.
Conservatively,
engineering
assumed that the dose
rate to the gate would be
1 Rem/hr, which translated into a 40-year cumulative
dose of 3.5 x 10'ads.
The memorandum
concluded that replacement of the seals
every 4 years to minimize exposure of the seals to less than 5 x 10'ads was not
necessary.
Therefore, engineering
recommended
that gate seals be replaced based
on the results of inspections performed following gate removal.
Subsequently,
in
December 1994, Preventive Maintenance
Basis 082288 was revised (Revision 1) to
reflect these recommendations
(i.e., inspect and replace as necessary).
The inspectors reviewed spent fuel pool seal maintenance
records and determined
that preventive maintenance
requirements
had not, in all cases,
been complied with.
The initial preventive maintenance
requirements,
as defined in Preventive
Maintenance Task 082288 and Master Instruction PMM09535, included
replacement of the spent fuel pool seals every 4 years.
None of the Unit 3 gate
seals have been replaced,
and the Unit
1 decontamination
pit gate seal was never
replaced up until the time the gate was welded shut in September
1996.
Initial
replacement of the Unit 2 fuel transfer canal gate seal and decontamination
pit gate
seal exceeded
the 4.-year limit by approximately 3 and 3-1/2 years, respectively.
The second replacement of the Units
1 and 2 cask loading pit gate seals exceeded
the 4-year limit by approximately 2-1/2 and 2 years, respectively.
Until the gate
seal preventive maintenance
requirements
were changed
in December 1994, the
licensee failed to replace the gate seals every 4 years in accordance
with prescribed
procedures,
which constituted
a fourth example of a violation of Technical Specification 6.8 (50-528;-529;-530/9709-01).
The spent fuel pool gate seal maintenance
history, beginning with the date of each
units'nitial criticality, is presented
in the following table.
Unit and Criticality
Date
Unit 1-May 25,
1985
Unit 2-April 18,
1986
Replacement
of
Spent Fuel
Pool Fuel
Transfer Canal
Gate Seal
June 1989
October 1992
March 1993
Replacement
of
Spent Fuel
Pool Cask
Loading Pit
Gate Seal
June 1988
December
1988
Replacement of
Cask Loading
Pit/Decontamination
Pit Gate Seal
Never replaced
October 1993
Unit 3-October 25,
1987
Never replaced
Never replaced
Never replaced
Since spent fuel pool gate seal replacement
is currently based
on visual inspection,
the inspectors reviewed the spent fuel pool gate seal inspection instructions to
determine if inspection attributes and acceptance
criteria were established.
In addition, the inspectors requested
information pertaining to personnel
performing the inspections
(i.e., training and qualifications),
Preventive
-17-
Maintenance Task 082288 specified inspection of the spent fuel pool gate
seals for evidence of damage,
wear, or deterioration after removal in,accordance
with Maintenance
Procedure
78MT-9ZF01, "Removal and Installation of Spent
Fuel Gates," Revision 4. The preventive maintenance
basis further stated
that the gate seals were to be replaced based on the results of the inspections.
Procedure
78MT-9ZF01 addressed
removal, inspection, replacement,
and
installation of the spent fuel pool gate seals.
Each gate seal was addressed
in a separate
section of the procedure; however, the inspection requirements
were identical.
The refueling and mechanical support personnel were instructed
to "Visually inspect for any signs of cracks or deformation that might require
replacement,
If seal damage
is suspected,
slowly move the gate to a lay down area
to permit further gate seal examination, if possible.'f gate seal needs to be
replaced, write a Work Request."
The inspectors considered the procedure to be inadequate.
It failed to prescribe
C
specific inspection technique or method, the necessary
inspection conditions (i.e.,
lighting, aided or unaided visual with respect to magnification, and scope or area of
the seal to be inspected),
or the training/qualifications of the personnel who perform
the inspection.
Licensee personnel informed the inspectors that the refueling.and
mechanical support craft performing the inspections
did not receive any special
training.
The inspectors ascertained
that there must be provisions for assuring that
the craft know what they are supposed
to be looking for, and that acceptance
criteria have been established
and understood.
The inspectors considered this a
failure to establish appropriate inspection guidance necessary to support the current
gate seal service life criterion, and therefore, constituted
a violation of Criterion V of
Appendix B to 10 CFR Part 50 (50-528;-529;-530/9709-03).
Conclusions
The inspectors identified a design control violation regarding
a failure to establish
provisions for assuring that the safety-related function of the gate seals would not
be lost,
The licensee,
had performed
a design bases validation which resulted in the
issuance of a condition report/disposition request that evaluated deficiencies in gate
seal design during a loss of offsite power and
a seismic event, and determined that
the most limiting condition would be a catastrophic failure of both the
decontamination
pit seals and the cask'oading
pit seals.
This resulted in the
licensee developing
a conservative modification to eliminate the need for the
decontamination
pit gate seal by welding the gate shut in each unit.
The inspectors identified a violation, regarding
a failure to comply with preventive
maintenance
requirements.
t
I
-1 8-
The inspectors noted that the spent fuel pool transfer canal gate seal had never
been provided with an alarm to detect or provide abnormal pressure'conditions,
nor
had any provisions been established
for conducting periodic monitoring of gate seal
pressure.
The inspectors identified a violation regarding
a failure to establish appropriate
inspection and training guidance to support the current gate seal service life
criterion.
E8.2
S ent Fuel Pool
Fuel Transfer Canal
Cask Loadin
Pit and Cask Decontamination
~Pit Desi n
a 0
Sco
e 92903
The inspectors reviewed the design of the spent fuel pool, fuel transfer canal, cask
loading pit, and the cask decontamination
pit, in order to determine the
consequences
of various scenarios
associated
with loss of gate seal.
b.
Observations
and Findin s
The licensee performed Calculation 13-NC-PC-202,="Cask Loading Pit Level
Requirements 5 Final Boron Concentration,"
in July 'l996, to set new design bases
criteria for spent fuel pool and cask loading pit levels, given that the
decontamination
pit gate was welded in place and the cask loading pit was filled
with non-borated
water, with a minimum and maximum water level. The minimum
cask loading pit water level was established
as 131 feet so that a failure of both the
cask loading pit and fuel transfer canal gate seals would not result in the spent fuel
pool cooling water pumps losing suction during a design basis accident.
The
minimum spent fuel pool water level required to avoid losing suction to the spent
fuel pool cooling water pumps was 131 feet 10 inches.
The maximum cask loading
pit water level value of 133 feet was to ensure that with a failure of the cask
loading pit gate seal, the maximum dilution of the spent fuel p'ool would not
decrease
spent fuel pool boron concentration below the Technical Specification
minimum level of 2150 ppm.
This analyses
included consideration of the status of the fuel transfer canal gate
valve PCN-V118.
This valve is located on the fuel building end of the fuel transfer
tube, and is used to isolate the fuel building from containment while in Modes 1-4.
The licensee had established
adequate
procedural controls over this valve.
The
valve was only allowed to be open during Modes 5 and 6, and when water level
was equalized on both sides of the valve.
-1 9-
The existing spent fuel pool cooling system design bases assumed
failure of the
pneumatic gate seals on the fuel transfer canal and cask loading pit gates.
In the
event that both of the gate seals failed, the overall equalized water level in the
spent fuel pool would not drop below 133 feet.
This analyses was a worst case
scenario that assumed
the initial Technical Specification minimum spent fuel pool
level, a dry transfer canal, and the minimum required water level in the cask loading
pit.
On the day of the event, the licensee calculated that with transfer canal gate seal
failure, and with approximately five feet of water in the transfer canal to cover the
fuel transfer tube (procedurally required for security considerations),
the spent fuel
pool level would have stabilized at 135 feet.
Analyses within these design bases
indicated that failure of these gate seals would not be safety significant.
Until the licensee completes the evaluation of the seal design criteria, the fuel
transfer canals in each unit have been filled to minimize the significance of gate seal
failure.
Conclusions
The licensee conservatively set new design bases criteria for spent fuel pool and
cask loading pit levels so that a failure of both the cask loading pit and fuel transfer
canal gate seals would not result in the spent fuel pool cooling water pumps losing
suction, and a failure of the cask loading pit gate seal, would not decrease
concentration
below the Technical Specification minimum level.
E8.3
Licensee Review of Industr
Information
a.
~Sco
e
This inspection effort evaluated adequacy of licensee actions as they pertained to
generic communications that are routinely provided from within the industry and
from the NRC (e.g., information notices, bulletins, and generic letters).
b.
Observations
and Findin s
The inspectors performed
a brief review of the licensee's
response to NRC Generic Letter 88-14, "Instrument Air Supply System Problems Affecting Safety-Related
Equipment."
The generic letter requested
each licensee to perform a design and
operations verification of the instrument air system, including verification that
safety-related
components
would perform as expected
in accordance
with all
design-basis
events, including a loss of the normal instrument air system.
-20-
A licensee letter dated February 20, 1989, stated that their review produced
a list
of 144 safety-related
components
(valves and dampers)
in each unit that interfaced
with and relied on the nonsafety-related
instrument air system during normal
operating conditions.
From the information provided by the licensee, it did not
appear that the safety-related
spent fuel pool gate seals were evaluated
in the
context of Generic Letter 88-14.
C.
Conclusions
The licensee's
evaluation of Generic Letter 88-14 did not appear to consider the
safety-related
spent fuel pool gate seals, which resulted in a missed opportunity to
assure that the seals would continue to perform their safety-related function upon
loss of instrument air.
V. lVlana ement Meetin s
X1
Exit Meeting Summary
At the conclusion of the onsite portion of the inspection on March 21, 1997, the
inspectors conducted
an interim exit meeting with members of licensee management.
At
the conclusion of the inspection on April 4, 1997, the inspector telephonically presented
the inspection results to members of licensee management..
The licensee acknowledged
the findings presented.
The inspector asked the licensee representative
whether any materials examined during the
inspection should be considered
proprietary.
No proprietary information was identified.
'
ATTACHMENT
SUPPLEMENTAL INFORMATION
PARTIAL LIST OF PERSONS CONTACTED
Licensee
P. Birchert, Shift Supervisor,
Unit 3, Operations
D. Fan, Section Leader, System Engineering
E. Flodin, Primary Plant Investigator, Nuclear Assurance
.
R. Fullmer, Director, Nuclear Assurance
J. Hesser, Director, Nuclear Engineering
W. Ide, Vice P'resident,
Nuclear Engineering
D. Kanitz, Senior Engineer, Nuclear Regulatory Affairs
A. Krainik, Department Leader, Nuclear Regulatory Affairs
J. Levine, Senior Vice President,
Nuclear
D. Mauldin, Director, Maintenance
H. Mortazavi, Senior Mechanical Engineer, System Engineering
R. Myrick, Department Leader, Mechanical Maintenance
G. Overbeck, Vice President,
Production
~
T. Price, Senior Mechanical Engineer, System Engineering
T. Radtke, Director, Outage and Site Integrated Scheduling
D. Smith, Director, Operations
J. Taylor, Department Leader, Unit 3 Operations
J. Velotta, Director, Training
Other
F. Gowers, Site Representative,
El Paso Electric Company
NRC
D. Kirsch, Branch Chief, Region IV
INSPECTION PROCEDURES USED
92901
92903
Followup-Operations
Followup-Engineering
0
4
-2-
~Oened
50-528;-529;-530
/9709-01, Ex.1
ITEMS OPENED AND DISCUSSED
Procedural Violation Regarding Installation Of Incorrect
Nitrogen Backup Cylinder For The Transfer Canal Gate Seal
50-528;-529;-530
/9709-01, Ex.2
50-528;-529;-530
/9709-01, Ex.3
50-528;-529;-530
/9709-01, Ex.4
50-528:-529;-530
/9709-02
50-528;-529;-530
/9709-03
Work Was Performed (Isolation Of The Instrument Air
System And Placing Backup Nitrogen In Service) Without
Documenting Or Statusing The Work
A Valve That Was Required To Be Locked Closed While
Refueling Operations Were In Progress,
Was Closed But
Unlocked, And Incorrectly Statused
As Open In The Control
Record
Gate Seals Were Either Not Replaced As Required, Or Were
Not Replaced Within The Time Limits Established
By The
Preventive Maintenance
Program
Provisions Were Not Established to Assure That The
Safety-Related
Function of The Gate Seals Would Not Be
Lost
The Gate Seal Inspection Procedure Was Inadequate
In
That There Was No Inspection Guidance,
No Acceptance
Criteria, And Personnel Training Requirements
Were Not
Established
T