ML20057A453
| ML20057A453 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/18/1993 |
| From: | Casto C, Matt Thomas NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20057A450 | List: |
| References | |
| 50-327-93-32, 50-328-93-32, NUDOCS 9309140233 | |
| Download: ML20057A453 (24) | |
See also: IR 05000327/1993032
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UNITED STATES
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/mm Mch 4
NUCLEAR REGULATORY COMMISSION
REGION 11
[ Te( % 101 MARTETTA STREET, N.W., SUITE 2iKO
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ATLANT A, GEORGIA 30323 0199
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49 ,8
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Report Nos.: 50-327/93-32 and 50-328/93-32
Licensee: Tennessee Valley Authority ,
3B Lookout Place 1
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1101 Market Street
Chattanooga, TN 37402-2801
Docket Nos.: 50-327 and 50-328 License Nos.: DPR-77 and DPR-79
Facility Name: Sequoyah I and 2
InspectionConduci: June 28-July 2,1993 and July 12-23, 1993
Inspector:
ty. Thomas
-n 6'M kN
Date Signed 1
Accompanying Inspectors: M. Morgan
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D. Roberts ;
/ // R. Schin .
Approved by: 42' * C b c h W 'S' ?
C. Casto, Chief Date Signed l
Test Programs Section !
Engineering Branch !
Division of Reactor Safety l
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SUMMARY
Scope:
This special, announced inspection was one of a series of inspections being
performed to assess the licensee's balance of plant (B0P) equipment and I
systems, and to evaluate the licensee's corrective actions being taken in l
response to B0P equipment that has been unreliable and has contributed to '
unplanned challenges to reactor safety systems. Findings identified during
this inspection will be followed up during subsequent inspections that will be
performed in this area prior to restart of the units.
Results:
In the areas inspected, the following findings were identified: i
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Violation for failure to follow procedures when no corrective
action program document was written to identify the problem and no
corrective actions were initiated after the air quality test did
not meet acceptance criteria for particulate for the safety
related portion of the control air system.
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9309140233 930820
O ADOCM 05000327 .
PDR i
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Inspector followup item (IFI) to followup on licensee actions to
l address weaknesses identified by the inspectors during
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implementation of a modification which made piping changes to the
main feedwater (MFW) system. !
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Weaknesses noted in the backlog review process included: 1) not i
all backlogged items had been reviewed by the Backlog Review l
Committee (BRC), and 2) B0P material condition'walkdowns were not
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scheduled earlier in the backlog review process. !
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In resnonse to deficient material conditions identified by the- !
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inspectors, TVA provided more walkdown ~ criteria and guidance to !
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the system engineers, lowered the threshold for deficient i
conditions, and brought in a third party to perform material i
- condition walkdowns independent of the syste:a engineers. These j
were considered positive actions taken by the licensee. '
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REPORT DETAILS !
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l I. Persons Contacted
Licensee Employees '
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- J. Baumstark, Plant Operations Manager
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- L. Bryant, Maintenance Manager
- M. Cooper, Restart Manager
- R. Driscoll, Site Quality Manager
- R. Fenech, Sequoyah Site Vice President !
I. Heatherly, Principal Mechanical Engineer, Nuclear Engineering
- D. Keuter, Nuclear Readiness Vice President
- D. Lundy, Technical Support Manager
- K. Meade, Licensing Engineer
- S. Poage, Nuclear Assurance Audit and Assessment Manager (Acting)
- K. Powers, Plant Manager
- J. Proffitt, Licensing Engineer
- J. Robertson, Independent Safety Engineering Manager
- H. Skarzinski, Technical Programs and Performance Manager
- R. Thompson, Compliance Licensing Manager
- P. Trudel, Design Engineering Manager
- J. Ward, Engineering and Modifications Manager 1
- N. Welch, Operations Superintendent
- K. Whittenburg, Public Relations Manager
Other licensee employees contacted included engineers, control room
l operators, shift supervisors, craftsmen, and other plant personnel.
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NRC Employees I
- A. Gibson, Director, Division of Reactor Safety, Region II
- W. Holland, Senior Resident Inspector
- P. Kellogg, Section Chief, Region II
- A. Long, Resident Inspector
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- S. Shaeffer, Resident Inspector
l * Attended exit meeting
Acronyms and initialisms used throughout this report are listed in the
last paragraph.
I 2. Plant Status
Unit I was in the refueling condition (Mode 6) to support a refueling
outage and Unit 2 was in the cold shutdown condition (Mode 5) for a
forced outage.
3. Background
During 1992 and early 1993, Sequ'oyah experienced a significant increase
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in the number of transients and reactor trips associated with secondary i
or B0P systems and equipment. Sequoyah Units 1 and 2 were shut down on
March I and 2,1993, following the rupture of an extraction steam line
(B0P system) in Unit 2. The steam line rupture was caused by
erosion / corrosion (E/C). After the units were shut.down, the licensee
developed a Sequoyah Restart Plan. The overall objectives of the
Restart Plan are to ensure the comprehensiveness of the restart efforts,
to provide an integrated framework for consistent and effective
implementation of those efforts, and to assist in the management and
communication of those efforts.
The purpose of the B0P inspections at Sequoyah is to evaluate the
corrective actions taken by TVA in response to the equipment problems
and determine if the corrective actions are adequate to ensure that the
material condition of B0P equipment and systems is acceptable prior to
unit restart.
4. B0P Assessments and Studies .
As a result of the adverse trend in the performance of the secondary
plant and the impact on reliability and availability at Sequoyah, site
senior management initiated a Secondary Plant Reliability Study in
January 1993. The objective of the reliability. study was to understand ,
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the root cause of the increased contribution of the secondary plant to
unit transients and reactor trips at Sequoyah and, based on this
understanding, provide specific recommendations to site management to ;
reduce the occurrence of secondary plant induced events. The licensee
also contracted Stone and Webster Engineering Corporation (SWEC) to
perform an independent design review of selected B0P systems in order to
identify additional problems or vulnerabilities in the 80P which could
jeopardize plant reliability.
l The results of the Secondary Plant Reliability Study and the independent
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B0P systems design review were reviewed by the inspectors and are
discussed in inspection report 50-327,328/93-22. Several questions
were raised by the inspectors during that inspection concerning the
studies. One question involved the omission of some reliability study
l results from the applicable system backlog notebooks. Licensee
l personnel indicated that the information would be incorporated into the ,
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notebooks. As a followup to this item, the inspectors reviewed selected l
system backlog notebooks during 'this inspection and found that the i
- reliability study information had been incorporated into applicable !
l notebooks. Other questions raised will continue to be followed up !
during subsequent inspections prior to restart.
In addition to the above studies, the licensee also had the Institute of
Nuclear Power 0parations (INP0) perform a special assistance visit to
- Sequoyah January 27-29, 1993. The visit focused on the identification
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of B0P material condition problems that could cause future plant
problems. The INPO visit identified a few potential equipment problems
and human performance issues related to the operation of BOP systems.
The results of the INPO visit were being reviewed by the licensee as
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part of the restart effort.
The inspectors will continue to follow licensee actions to address the
l findings identified in the various B0P assessments and studies.
5. Design Changes and Plant Modifications (37700)
a. Plant Modifications to Improve the Reliability of B0P Systems
The inspectors reviewed the licensee's initiatives to identify and
implement plant modifications to improve the quality of various
B0P systems whose performance could affect or challenge safety
related systems. Documentation reviewed included the June 9, 1993
Secondary Plant Reliability Study, the system engineers' systems
books, and the licensee's restart list. Outstanding DCNs for
affected systems had been reviewed by the BRC, the MRRC, and the
system engineers prior to addition to or deletion from the restart
list. Documentation for those reviews were included in the
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systems books. The inspectors compared the outage-related DCNs to
! various issues that had been identified in the reliability study
to verify that reliability issues had been sufficiently addressed
by the modifications. Noting that some of the issues identified
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in the reliability study had not been determined to be restart
items, the inspectors revi,ewed the disposition of these items and
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concluded that non-restart modifications had been properly
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classified.
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The inspectors' overall conclusion was that the licensee had
properly reviewed and classified secondary plant modifications
with respect to their status on the Unit I and Unit 2 restart
schedules. No concerns were identified by the inspectors.
b. Planning, Development and Implementation of Modifications
The inspectors reviewed applicable FSAR descriptions and design
specifications for the DCNs listed below. The DCNs were reviewed
to determine the adequacy of the safety evaluations performed to
meet 10 CFR 50.59 requirements where applicable; to verify that
the DCNs were reviewed and approved in accordance with applicable
administrative controls; applicable plant documents (drawings,
plant procedures, FSAR, TS, etc.) were revised to reflect the
subject modifications; and post modification test requirements
were specified. The inspectors reviewed DCNs for the Control Air
System, Condensate System, Main Feedwater System, and the
Condenser Circulating Water System.
Control Air System Modifications
DCN-M-09349-A
This modification will install bypass lines for auxiliary
air moisture traps and will install larger drain lines for
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l the SCSA receiver tanks. This DCN will also install
stainless steel tubing to the compressor unloader valves
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and to the control air control panel. The larger drain ,
lines for the three receiver tanks will allow for better '
draining of water from those tanks. The stainless steel
tubing upgrade for the unloader air supply will make the
unloader air line more reliable. The unloader air line is l
common to the four turbine building compressors and its '
failure could result in the loss of all four compressors.
Installation of the bypass line near the moisture traps will
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allow personnel to check for excess water in the air system
in the vicinity of the auxiliary control air receiver tanks.
The inspectors observed part of the installation of the
moisture trap bypass line in the "A" ACA system.
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DCN-M-09507-A
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This modification will lower the control air high moisture
alarm setpoints front six percent relative humidity (RH) to
two percent RH in order to inform operators earlier of a
potential abnormal condition. The DCN will also install a
redundant pressure control circuit to back up the normal
control scheme. Originally, the SCSA compressors' common
contrcl circuit was subject to a single failure which could
practat all four compressors from starting on demand. In
tSe past this failure mode has resulted in a plant shutdown.
The new configuration should result in a more reliable
control air system in which the redundant pressure control
circuit will start all four compressors when system pressure .
has decreased to below 88 psig. !
DCN-M-09350-A
This modification installed additional valves and piping to
supply the Unit 2 condensate booster pumps from the Unit 2
air header. It also installed valves to allow isolation of
the abandoned portion of the old water treatment plant.
i Finally, the DCN installed drain traps at the drain valves
l accociated with the service air isolation valve. Although
this modification had been physically completed, affected
procedures had not been revised prior to the end of the
inspection period. -
DCN-M-09151-A
This modification installed air filters in the control air
supply lines to the four Unit 1 MSIVs. The inspector
reviewed this modification and toured the affected area of
the plant as a followup to IFI 50-327, 328/92-34-02. This
IFI is discussed in more detail in paragraph 8.b. of this
inspection report.
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The above four modifications were the only control air system l
modifications designated by the licensee as restart items. The
inspector noticed that only one of the modifications, DCN-M-09151-
A (for the air filters), had been completely implemented by the
end of the inspection period; therefore an overall assessment of
the licensee's implementation of design changes for the control
air system was not done by,the inspector. However, the inspectors i
reviewed the design packages for all four DCNs and concluded that
the packages specified adequate post modification testing
requirements, and that they included detailed 50.59 reviews in
accordance with NRC regulations. No concerns were identified.
Condensate System Modifications ,
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DCN-M-09479-A i
This DCN revised the condensate demineralizer pump stop
sequence to prevent pump restart due to flow control valve
limit switches being too slow to block the start signal.
This was essentially accomplished by separating the controls
for the pumps and the valves so that the components could be
operated manually.
DCN-M-09473-A
This DCN revised the control logic for the condensate
booster pumps to insure that the suction isolation valves
start closing before the auxiliary oil pumps start. The
modification involved removing automatic start features for
the pumps and valves which had been the source of feedwater
system operating problems over the years.
Both condensate system restart modifications had been installed by '
the end of the inspection period. The inspectors reviewed the
design packages and concluded that adequate instructions, safety
reviews, and post modification testing requirements had been
documented. No concerns were identified by the inspectors.
Main Feedwater (MFW) System Modification
DCN-G-8937-B
This generic DCN involved replacing carbon steel piping
components with erosion / corrosion (E/C) resistant materials
(chromium molybdenum steel or stainless steel) in selected
BOP systems and some safety related systems which had
excessive pipe wall thinning due to E/C of the carbon steel.
The inspectors reviewed modification activity associated
with the MFW system as part of the B0P system backlog review
effort. Stainless steel piping was installed in portions of
the MFW system. The. MFW system piping replaced was TVA
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. Class H (wiiich is non safety related) non-ASME Code Class.
l The Code of record for this replacement is ANSI B31.1, 1967
edition. .
l The inspectors reviewed the safety evaluation for the DCN
- and the associated work instructions for replacing the MFW
j piping. The safety evaluation specified that individual
j sections of stainless steel pipe used as a replacement
- material for carbon steel, be limited to 50 inches or less
1 in length. This limitation was to account for the
" difference in thermal growth between the carbon steel and
the stainless steel and precluoe exceeding stress criteria.
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Any replacement sections in excess of 50 inches required
! engineering approval prior to installation. The inspectors
] performed field inspections to determine if the piping was '
installed in accordance with the DCN requirements and found
j newly installed stainless steel sections of MFW piping that
- exceeded the 50 inch limitation. The inspectors discussed
this item with Modifications Department and Nuclear
i Engineering personnel and determined that Nuclear
] Engineering was not aware of these deviations from the
i safety evaluation. Engineering had not approved the !
j deviations nor had they performed an evaluation to determine !
- their acceptability. Engineering personnel stated that a '
! piping analysis would be performed prior to restart to ,
- determine if any the~rmal growth stress criteria would be "
l exceeded due to the deviation. The inspectors informed'the ,
! licensee that followup on the resolution of this issue will :
- be identified as IFI 50-327,328/93-32-02, Resolution of Main '
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- Feedwater Modification Discrepancies.
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During further review of the work instructions which
j implemented the MFW system portion of the DCN, the
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inspectors noted that some of the PMT requirements specified
by Engineering were not incorporated into the work
instructions (WR C173812). Engineering specified that all
the associated new welds be inservice leak tested at full
i system operating conditions. The leak checks were specified
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in addition to the welds having been 100 percent radiography
tested (RT). The RT satisfied the ANSI B31.1 Code
- requirement without the leak checks. However, the
inspectors noted that the WR only specified performing an
inservice leak check of the pump discharge flanges at full
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system operating conditions. Further, the inspectors noted
- that the piping and welds were insulated. Licensee
! personnel indicated that the insulation would not be removed
l during the leak checks. The inspectors noted that the WR
i did not contain provisions to perform the leak checks in
l accordance with Appendix D of Engineering Specification G-
29, Specification for Hydrostatic Testing. G-29 specifies
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that the test pressure shall be maintained for a minimum' of
four hours prior to examination for insulated piping.
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Licensee personnel indicated that the WR would be revised to
incorporate all the PMT requirements specified by
Engineering prior to restart. The inspectors informed the
licensee that resolution of this issue will be followed up
in conjunction with IFI 50-327,328/93-32-02 above.
The inspectors concluded that the deficiencies discussed :
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above do not constitute a violation of NRC requirements
because they involved non safety related activities.
However, the deficiencies did identify a weakness in the ,
implementation of this DCN with regard to DCN' requirements
not being effectively translated to work documents and ,
implemented.
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Condenser Circulatina Water (CCW) System Modifications
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DCN-M-9548-A and DCN-M-9549-A
These DCNs involved installing new isolation valves in the l
motor bearing cooling water-(MBCW) supply to the Unit 1 CCW
pumps and the MBCW supply to the Unit 2 CCW pumps. The MBCW
supply lines to the CCW pumps could not be isolated between
Unit I and Unit 2. This issue was identified as a high
priority item in the Secondary Plant Reliability Study due i
to the inability to perform system maintenance because there
was no means of isolating between units when one or both '
units were operating. This change will facilitate system- ;
maintenance and improve reliability by providing a means of !
isolating between the units. Both DCNs had been installed
and 1.he inspectors p'erformed a field inspection to verify
that the isolation valves were installed in accordance with
the applicable DCNs. The inspectors did not identify any
j discrepancies. ;
6. B0P System Backlog Review Process $
The inspectors continued reviewing the system backlog notebooks and the
licensee's implementation of the backlog review process. During this
review the inspectors have noted some weaknesses in the process which
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have led to a concern over whether all backlogged items have beer
identified and evaluated for restart. The following observatiot were
noted by the inspectors:
Failure to review Customer Group testing, preventive maintenance, i
and relay calibration backlogs (inspection report 50-327,328/93- .
31). t
- The backlog of open test deficiencies for non Technical i
, Specifications (TS) tests do not appear to have been reviewed in
the backlog review process. An example is discussed in the NOV
and paragraph 7.a. of this inspection report.
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- Licensee decision to not perform system walkdowns for material
condition before the backlog review process started. Numerous
material condition deficiencies have been identified during these <
later walkdowns taat have significantly expanded the scope of i
restart work items and resulted in schedule delays. The !
inspectors noted that, in response to deficient material !
conditions identified by the NRC during walkdowns, TVA provided i
more detailed guidance and walkdown criteria to the system ;
engineers, lowered the threshold for deficient conditions, and ,
brought in a third party to perform material condition walkdowns ;
independent of the system engineers. These latter actions were ;
considered to be positive steps taken by the licensee. l
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- Restart items were deleted from the outage schedule for over a !
month (May and part of June) without the knowledge or approval of ,
the system engineers, BRC, or MRRC. This item was identified by '
the licensee. The licensee took appropriate actions to put the '
restart items back on the outage schedule and correct the process .
that allowed the items to be deleted from the schedule. i
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The inspectors held discussions with licensee personnel concerning ,
actions taken by the licensee to address these items. The inspectors
also questioned if other measures were being taken to provide assurance ;
that all backlogged items are being reviewed for restart. The !
inspectors will continue to follow this concern during subsequent ,
inspections prior to restart. -
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7. MFW System Backlog Review i
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The inspectors reviewed the backlogs for the MFW system. This included ;
reviewing the system backlog notebooks and performing preliminary system
l walkdowns to observe material conditions. Additional systems were !
reviewed and are discussed in NRC inspection reports 50-327,328/93-22,
! 93-26, 93-27 and 93-31.
l The inspectors reviewed the MFW* system description provided in the FSAR. !
The licensee's Secondary Plant Reliability Study dated June 9,1993, was
reviewed to determine the scope and depth of efforts to identify
necessary MFW items for repair or modification prior to the restart of
the units. In addition, an independent, third-party, engineering
evaluation of the feedwater system was reviewed to determine if
recommendations were included in work to be accomplished before unit l
restart.
The inspectors reviewed the backlog of open work requests and other
documentation for the MFW system to identify items to be worked prior to
i the Unit 1 and Unit 2 restarts. The plant Backlog Review Committee's
(BRC) disposition of these items was also reviewed. The inspectors
found that appropriate recommendations had been made by the BRC for
items to be worked prior to the Unit I and Unit 2 restarts. The
inspectors considered administrative control of MFW system restart
issues to be adequate.
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The MFW system is not safety related and consists of four (two per unit)
turbine driven MFW pumps (MFPs) located between respective "A-train" and
"B-train" intermediate / low pressure (#2) FW heaters and the "A-train" i
and "B-train" (#1) high pressure FW heaters. The system (for each unit)
also contains four FW regulating valves and four FW bypass valves; one
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set for each unit steam generator,
a. Operational History
The inspectors reviewed the history of MFW system operation
i and noted licensee corrective actions for operational j
problems encountered. These corrective actions were checked 1
to verify completion or inclusion on the restart list.
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Sequoyah has experienced a history of MFW system problems:
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Erratic MFW regulating valve operation due to location I
i of solenoids and high vibration conditions. '
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FW heater drain level control, at times, erratic or l
otherwise " unstable" during transient operating
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MFW leaks at the MFP discharge check valves. Original
design of the check valves failed to maintain sealing
area between the check valve cover / bonnet and the
valve body. Furmanite was used routinely to correct
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this and other feedwater system leakage problems. ;
The original design MFP hydro-mechanical governing oil
system has praven to be unreliable.
Low MFW suction pressures experienced during
transients. Possible problem with original " tuning" ,
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of system flows, NPSH adequa:y, system operating I
procedures and general system design.
Higher than expected levels of " wall thinning" in the
MFW system piping and joints. This " thinning" was l
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especially notable in the short radius elbows and some !
of the MFW system " tees". !
Inadequate FW heater shell safety valve size and
design of safety valve discharge piping. These ;
inadequacies may have been contributors to higher than ;
- expected backpressures in the heaters and subsequent
effects on relief valve setpoints.
As evidenced by recurring problems with the MFW system, the
licensee's corrective actions have not been adequate nor
timely to prevent other problems with the MFW system from
occurring. The licensee's proposed restart list includes
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corrective actions for each of the above problems.
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Piping elbows, MFW pump discharge runs and " susceptible"
- carbon steel piping which have been replaced with stainless
steel (SS) components and transition pieces should improve
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system reliability. Those MFW system items which are
proposed for replacement, repair, or modification, should
also improve system reliability.
b. System Walkdown
A walkdown of the MFW system was performed to verify an ,
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appropriate material condition prior to plant restart and to
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verify that significant problems had been identified and
evaluated by plant personnel for inclusion in the restart
list. Major components inspected included "new" SS elbows,
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pump discharge piping and transition joints between the SS
components and the original carbon steel piping. The
following summarizes the results of the walkdown:
Newly installed SS piping, transition pieces and some
of the SS elbo'ws were insulated. The inspectors
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discussed this observation with licensee personnel and
- questioned if the insulation would affect the post
modification examinations and inspections. During
further followup of this question, the inspectors
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reviewed the modification (DCN-G-8937-B) and the WR
(WR C173812) which installed the new piping. Concerns
. over implementation of this DCN and the inadequacy of
! the PMT specified in the WR were identified as an IFI
and are discussed in paragraph 5.b. of this inspection
report.
The original carbon steel MFW pump discharge piping
short radius elbows, located immediately downstream of
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the discharge check valves, were still covered with
"old" insulation material and were not marked as E/C
q control survey points. During further followup of
this observation and discussions with licensee
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personnel, the inspectors determined that the E/C
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survey points were being determined using the CHECMATE
program, industry experience, and engineering ,
judgement. The inspectors reviewed the methodology
for selection of MFW piping components and layout of
inspection points for E/C inspections during this
outage and determined that E/C of MFW piping was being
adequately addressed. The Unit 2 MFW piping elbows in ;
question were inspected to determine the extent of 1
wall thinning using a screening ultrasonic thickness !
measurement program (irs 50-327,328/93-10 and 93-12).
In addition to evaluation of the licensee's screening i
inspection program, the inspectors observed during l
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field inspections that one of the Unit 1 MFW pump
discharge elbows had been grid marked for inspection ,
and input into the CHECMATE program. The licensee's l
E/C program has been reviewed previously and is !
discussed in greater detail in NRC inspection reports ,
50-327,328/93-04, 93-10, 93-12, 93-24, and 93-30.
This MFW system modification involved the welding of
stainless steel piping and transition joints to the
original carbon steel piping. The inspectors
questioned whether the effects of thermal expansion
differences for the two materials had been considered.
During further followup of this question, the
inspectors held discussions with Engineering personnel
and reviewed DCN-G-8937-B and found that this question
was adequately addressed in the safety evaluation for
the DCN. However, during a field inspection to verify
proper installation, the inspectors identified that i
the stainless steel piping was not installed in
accordance with the DCN. This issue was identified as
an IFI and is discussed in greater detail in paragraph !
5.b. of this inspection report.
The above items will continue to be reviewed during future
NRC inspections prior to restart.
c. Assessment of Backlog Notebook ,
l The system engineer, following guidance contained in the
licensee's restart plan, had compiled backlogged information
for the following items: 1) "in the outage" WRs, 2) "not in
the outage" WRs, 3) .a MFW isolation valve SSPS relay WR, 4) I
! DCNs, 5) MILS, 6) CAQs, 7) IIs, 8) TFARs, 9) TACFs and 10) !
Secondary Plant Reliability Study items. l
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l (1) "In The Outage" WRs - Licensee Evaluation / Corrective '
Action
l While the Unit 2 WRs were emphasized as " desirable for
restart" WRs, both unit 2 and unit 1 "in the outage"
MFW WRs were listed. WRs which involved system
circuitry adjustment / replacement were definitive and
specified requirements for inspection, troubleshooting
and repair / replacement of the circuitry component
- (switch, relay, solenoid, etc...); should such
i
repair / replacement become necessary. WRs which
involved repair / replacement of mechanical components
(valves, small-bore drain piping, insulation, etc...) :
tended to give specific direction should such
repair / replacement become necessary. However, WRs
which involved ultrasonic or other nondestructive
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testing of piping / piping components; those written to l
be somewhat " global" or " generic" in nature, [(1:.e.- '
WRs written as being "various" for piping UT !
applications (E/C items)], were quite " nebulous" and ;
" undefined". During further followup of this item, i
the inspectors reviewed selected WRs involving i
ultrasonics and found that, although the WR cover i
sheets did lack some detail, the accompanying WR !
package contained detailed instructions for the j
ultrasonic inspection process. . This included j
designating areas to be inspected, detailed ,
requirements for inspection and documentation of the l
inspection results. At the time of the inspection, 42 !
Unit I and 33 Unit 2, " restart" WRs were identified !
for completion.
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,
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(2) "NOT In Outage" WRs - Licensee Evaluation / Corrective .
Actions
These WRs were quite specific and well-' defined. They
involved, for "the most part, MFW pump / valve packing ,
replacements, FW deaeration modifications, chemical j
cleaning of MFW components, S/G manway/handhole cover )
replacements, sludge lancing, MFW drain valve i
replacement / repair and ;aubber replacement / repair and
testing. At the time of the inspection, 3 Unit I and
34 Unit 2, "not in outage" restart WRs were identified
for completion.
(3) Crydon Relay Troubleshooting WRs - Licensee Corrective
j Actions
This WR was very specific to troubleshooting and
replacement of relays which serve as an SSPS input for
the Unit 2, loop 4 MFW isolation valves. It was also
denoted as being required for unit ~ restart. -At the-
time of this inspection, one Unit I and ore Unit 2,
" relay" WR was identified for completion. Overall,.
the licensee's WR backlog assessment was adequate.
(4) Design Change Notices (DCNs) ,
!
At the time of;this inspection, the system engineer !
had identified four DCNs per unit. One DCN had been !
denoted as being required for restart and it involved l
the " potential sealing with Furmanite" of the MFP !
discharge check valves (should gasket seating surface l
modifications / repairs fail). This same DCN involved ;
the potential "Furmaniting" of leaking MFW flow ;
elements and possible replacement of level switches. !
The two "not required.for restart" DCNs involved i
rescaling of system flow transmitters and ;
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1 recalibration of MOV torque switch settings. The i
l remaining DCN, involving installation of LEFM l
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electronics, was rendered obsolete by use of a
,
current / updated ultrasonic system. Overall DCN
i backlog assessment, by the licensee appeared to be
adequate.
i l
(5) Haster Issues List (MIL) Items l
At the time of' this inspection, the MFW system
engineer had identified 13 MIL items. The six l
" restart" MILS, included, replacement of,1) solenoids '
on the Unit 1 & 2 MFW regulating valves, 2) solenoids
- on the Unit 1 & 2 pneumatically-assisted check valves
1
and 3) "KI" relays on the Unit 1 & 2 regulating valve
controllers.
The seven "non-restart" MILS, included,1) relocation
of a Unit 1 MFW pressure transmitter "PT-3-34", 2)
, replacement of a damaged MFW flexible conduit in the
Unit 1 & 2 main steam valve vaults, 3) installation of
instrumentation to mitigate flooding in the Unit 1 & 2
main steam valve vaults and 4) replacement of obsolete
,
Foxboro "H-line" Unit 1 & 2 MFW regulating valve
controllers.
'
, At the time of this inspection, three of the above i
"non-restart" MILS and three of the " restart" MILS
were complete. Overall MIL backlog assessment by the
, licensee appeared to be adequate.
(6) Conditions Adverse to Quality (CAQs)
- At the time of this inspection, the MFW system
j engineer had identified six CAQ items. The four
'
" restart" CAQs, included,1) re-analysis of MFW piping l
elbows replaced in the 1992 outage - minimum wall l
. thickness questionable due to fabrication bending
!
process, 2) analysis of Unit 1 FW nozzle cracks, 3)
'
analysis of challenges to operators due to S/G loop
recorder problems, and 4) analysis of incorrect coil 4
voltages in the Units 1 & 2 Foxboro controller relays.
The two "non-restart" CAQs, included,1) performance
of a verification / validation of MFW system " Leading
Edge" flowmeter software, and 2) a CAQ which was
- superseded by an Incident Investigation report dealing
i
with nozzle cracking. Overall CAQ backlog assessment,
by the licensee appeared to be adequate.
(7) Incident Investigations (IIs)
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At the time of this inspection, the MFW syster
engineer had identified three II items. The two
" restart" Ils included,1) expansion of configuration
- control to cover plant MFW systems controlled by
l operations and 2) checks on FW nozzle cracks with ,
l
nozzles being in service for less than one year. -
l
The one "non-restart" II dealt with a Unit 1 #3 S/G
nozzle crack. At the time of this inspection, the
above "non-restart" II was incomplete and both
" restart" Ils had been completed.
Overall II backlog assessment appeared to be adequate.
(8) Trending Failure Analysis Reports (TFARs) !
l At the time of this inspection, the system engineer
! had identified one TFAR item and which was considered
a " restart" issue. Listed reports were received by i
l
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the licensee's Technical Support group prior to May 1, l
1993 and issues contained were to be addressed or
resolved prior. to the restart.
l
Overall TFAR backlog assessment appeared to be
adequate. l
(9) Temporary Alterations (TACFs)
At the time of this inspection, the system engineer
identified one TACF issue and this issue was
considered "non-restart" since the valve listed (a
temporary unit 2 isolation valve) had been removed.
Overall TACF backlog assessment appeared to be
adequate.
(10) Secondary Plant Reliability Study Items
At the time of this inspection, the MFW system
engineer had identified 32 items from Attachment "R"
of the reliability study (16 per unit). The overall
Attachment "R" backlog assessment appeared to be
adequate.
d. Third Party Review ~
A third party review of selected BOP systems was performed
by SWEC. The MFW system was one of the systems reviewed.
The inspectors verified that the recommendations identified
in the review which affected the MFW system were addressed
by the licensee. One of the MFW recommendations was
identified as a restart item. ihe other MFW items were
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considered to bc non restart. The restart item involved
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checking the adequacy of the feedwater heater shell safety i
relief valves' discharge line sizing and location. The l
licensee contracted SWEC to perform an evaluation. The !
l results of the evaluation recomended replacing all the i
i relief valves and performing some piping rework. The !
evaluation further concluded'that imediate repair of this l
condition was not necessary based on the existing system ,
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configuration and controls capabilities. It was considered l
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safe to operate the plant as-is until the Cycle 7 refueling )
outage. ;
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! The inspectors reviewed the SWEC recommendations for MFW and
the evaluation performed for the restart item and concluded j
that the actions taken to address the issues were ;
satisfactory. j
e. Overall Assessment of MFW Backlog ;
From the review of outstanding work / design items and the
j system walkdown results, the inspectors considered that the <
'
appropriate work items had been completed or were scheduled
to be completed prior to restart. 'However, due to the
significant impact the MFW system has hsd and will
potentially have on Sequoyah's safety systems, the
l
inspectors will continue to follow the resolution of the IFI
l
raised during this review.
l
8. Licensee Actions on Previously Identified Inspection Findings (92701,
, 92702)
- -
a. (Closed) URI 50-3?7,328/90-25-03; Compliance with GL 88-14 1
(Instrument Air) Comitments
This 1990 MTI unresolved item was for further inspection to
! determine the extent to which licensee comitments in response to j
GL 88-14 had not been met. The licensee's response letter to the !
NRC of February 23, 1989, stated that their preventive maintenance
program for the nonsafety SCSA and safety-related ACA systems
provided for replacing filters and dryer dessicant on a regularly
scheduled basis. However, the MTI did not find records of semi-
annual replacement of the ACA system filters. The inspector
reviewed records of completed semi-annual PMs 1488 and 1489 from
1988 through 1992, and found that the A and B train ACA dryer
prefilters and afterfilters had not been routinely inspected or
replaced semi-annually, but had been replaced at least annually
during that period. The replaced filters were found to be either
clean or slightly dirty / oily, but not excessively dirty. Licensee-
records showed that PMs 1488 and 1489 had last been done in
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j February 1993 and December 1992, respectively. The inspector
concluded that, while thes~e PMs had not been performed semi-
, annually, they had been performed sufficiently often to support
! the operability of the ACA system.
The 1993 MTI found that annual PMs 1450 and 1451, to replace the
'
dessicant in the A and B train ACA dryers, had not been performed
since February 1986 and August 1988, respectively. In response,
i the licensee stated to the MTI that WRs had been issued to replace
i the dessicant and that the PMs would be categorized as
i "Pegul atory." The inspector reviewed records of completed annual
1
PMs 1450 and 1451 from 1988 through 1931 and confirmed that PM '
3 1450 had not been performed in 1988 or 1989 and that PM 1451 had
i been performed in 1988 but not in 1989. The inspector also found
- that both PMs 1450 and 1451 had been performed in September 1990,
t including replacement of dessicant, and that the PMs had been
identified as " Regulatory." The PMs had also been performed in
September / October 1991, including inspection (but apparently not
- replacement) of the dessicant. (The PMs required dessicant
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replacemant only if it did not meet certain visual inspection
criteria.) PMs 1450 and 1451 were not performed in 1992, and were
most recqntly performed in February 1993. The inspector concluded
that, while these PMs had not been performed annually, they had
been performed s1fficiently often since 1990 to support the
s
operability of the ACA system.
'
The 1990 MTI found that the moisture alarm elemant setpoint l
4 verifications had not been accomplished and that no PM existed to
) implement schedu7ing of the calibration procedure that had been
4
written. The li.:ensee's CL 88-14 commitment status letter to the
- NRC of February J'4, 1990, stated that on August 28, 1989, plant
procedures had been revised to require routine setpoint
verification of moisture elements in the ACA and SCSA systems.
.
The inspector reviewed records of completed annual PM 5101, for
>
moisture switch calibration, and found that it had been completed
l in October 1990 and October 1991. The PM hid not been
- accomplished since then pending a modification (DCN M9507) to
! enable the element to be taken out of the line during calibration
i testing per vendor recommendations. The problem was documented in
the licensee's corrective action program as PER 930254. Also, the ;
!
modification and calibration were on the restart list as items to
be completed prior to restart.
In their letter to the NRC of February 14, 1990, the licensee
stated that routine air quality testing of the ACA and SCSA
1 systems was implemented on, September 12, 1989. The limits on air
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quality in the ACA and SCSA systems are to support the operability
- of those other safety-related systems serviced by ACA and SCSA, >
1
including Auxiliary Feedwater, Control Room Ventilation,
Containment Emergency Gas Treatment, Auxiliary Building Gas
Treatment, Containment Vacuum Relief Valves, and Main Steam
Isolation Valves. The 1990 MTI noted that the initial air quality
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tests in September,1989, resulted in several failed sample points j
for particulate and dew point. After several retests, all sample -
points finally passed the test in July, 1990. Then on October 26, !
1992, an event occurred where approximately 1,000 gallons of water !
were introduced into the SCSA system. The inspector reviewed i
records of completed semi-annual air quality tests (0-PI-SXX-032- !
001.0 for the turbine building and 0-PI-SXX-032-002.0 for the ,
auxiliary building) that had been conducted twice in 1991 (in
March and August / September), once in 1992 (in Aprir and once in -
1993 (in January). In addition, the inspector res m d a test for
dew point only (not particles) conducted in October / November 1992,
after the water intrusion event. The system engineer stated that
complete air quality tests were also conducted in about October
1992 and in June 1993, but could not locate the records for the . -
October 1992 tests and had not yet received the laboratory results i
from the June 1993 tests. The January 1993 test results (received l
from the test laboratory on March 8,1993) for the auxiliary *
building did not meet the acceptance criteria for particles in !
five samples (three test samples from the SCSA and two from'the l
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ACA were worse than control samples). Also, the test results for
two samples from the turbine building (SCSA) did not meet the
acceptance criteria. Both test packages were still open pendin9
satisfactory retest. The -inspector noted that deficiency notices .
for failing the particulate tests were described in the PI test !
packages and were listed as comments in the D rveillance ;
Instruction Delinquent List, Section C (periodic tests over 30 ;
days since completion that are delinquent to Document Control). :
Also, after the test results were known in March, 1993, the l
licensee had continued the monthly control air system blowdowns '
that had been started after the water intrusion event. I
Correction of the unsatisfactory ACA and SCSA air quality had not I
been adegn=tely acidressed by the licensee. In summary:
-
Since the 6ctober 1992 water intrusion event, the SCSA and
ACA systems had not passed an air quality test for
.
particulates. This test stated that it was to be
i accomplished at least semi-annually. Periodic air quality
testing was a licensee commitment to the NRC in response to
-
An air quality test for particulates was performed in
January 1993. Laboratory results of the test came back on
March 8, 1993, and showed unacceptable particulate content
in five samples from the SCSA and two samples from the ACA. !
Deficiency notices describing the particulate failure were '
in the plant instruction test packages. Test deficiency
notices are not an ACP document. Retest samples were not
taken until June, 1993, and those sample results had not yet
been received from the laboratory by the end of this
inspection (July 23,1993). The January air quality test
package remained open as of July 23, 1993.
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Although required by SSP-8.1, no PER or other ACP document
j was written on the failed air quality test, and the
unacceptable air quality in the SCSA and ACA systems was not
identified on the restart list as an item to be corrected ,
prior to restart. I
r ,
) The licensee's failure to follow procedures when no ACP document l
was written to identify the problem and no corrective actions were i
t initiated for the failed ACA and SCSA air quality tests of January l
- March, 1993, will be identified as a violation 50-327,328/93-32-
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- 01, failure to Follow Procedures for Failed ACA and SCSA Air
j Quality Tests.
l
- The insoector also identified concerns with the licensee's air
quality' testing process:
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The method of sampling was not compatible with the .
acceptance criteria / The acceptance criteria for ACA and '
SCSA was no particles greater that 3 microns and 5 microns, l
respectively. However, many test samples that had particles l
, greater that 3 or 5 microns were judged by the licensee to l
j meet the acceptance criteria. This was done in order to ,
- pass air quality tests from 1991 to date. The test samples I
j were judged by the licensee to be acceptable if they had no l
l
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more particles (grer'a that 3 or 5 microns) than the
control samples, which also contained many particles greater
j than 3 or 5 microns. This method did not assure that there
were no particles greater than 3 or 5 microns in the ACA or
j SCSA systems. The system engineer stated that both the test
- and control samples were routinely contaminated by the air
4
in the auxiliary and turbine buildings,
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The timeliness of laboratory analysis did not support prompt
corrective action for unsatisfactory test results. Two
-
months (January - March) was too long to wait for laboratory
test results for air particulate samples. The system
, engineer stated that it usually took about one month to get
,
lab results. He stated that the lab was located nearby in
, the Chattanooga area and was owned by TVA. He also stated
j that the time needed in the lab to perform the testing on
these samples should be less than one week.
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The content of laboratory reports was incomplete. The lab
. reports did not state the criteria against which each sample
was tested. For example, the lab report stated the number
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of particles counted in each test sample, but did not state
that these were the number of particles greater than three
, micron (ACA acceptance criteria) or five micron (SCSA
,
acceptance criteria). The incomplete information on the lab
report left opportunity for errors.
The inspector noted that the FSAR incorrectly stated that the SCSA
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and ACA prefilters were designed to remove foreign matter down to
3-micron size and the afterfilters were designed to remove foreign
matter down to 5-micron size. The licensee's February 23, 1989,
letter to the NRC stated that the SCSA and ACA prefilter
filtration ratings were 3 and 0.9 micrometers, respectively, and
the afterfilter ratings were 5 and 0.9 micrometers, respectively.
The inspector reviewed the filter numbers called for in the work
packages, the manufacturer's information on the filters, and
looked at the filters in the licensee's parts warehouse and
confirmed that the ACA prefilters and afterfilters were identified
as 0.9-micron filters. However, the SCSA prefilters and
afterfilters in the warehouse were not marked as to particle
filtration ability. Also, the system engineer was unable to
I locate documentation of that filtration ability by the end of the
inspection. i
In summary, the inspector noted that, while some control air
system PMs (ie. changing filters and dessicant) had not been
t accomplished at the stated frequencies, there had been no
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instances noted of unacceptably degraded filters or dessicant.
The inspector concluded that, since 1990, the licensee's actual
frequency of performing the PMs committed to in response to GL 88-
14 was adequate to support operability of the ACA and SCSA
systems. Therefore, URI 50-327,328/90-25-03 will be closed.
l However, the following issues will continue to be reviewed during
future inspections.
-
moisture alarm element setpoint verifications since 1991 (a
licensee PER was written on this and it was on the restart
list to be completed prior to restart); and
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air quality testing since October, 1992 (see VIO 50-
327,328/93-32-01 above).
b. (0 pen) IFI 327,328/92-34-02: Lack of Air System Component
Filters.
Following a review of the licensee's justification for not
providing air filters for safety related control air end users,
the inspectors raised a concern with the licensee's conclusion
that six non-essential air supplied components did not need
filters. The concern was based on the fact that the non-essantial
air system had experienced water intrusion resulting in potential
corrosion product particulate formation in the headers. The
licensee understood this concern and implemented modification DCN-
M-09151-A which installed filters for each of the Unit 1 MSIVs.
The inspectors' concern, as discussed in Inspection Report 50-
327,328/92-34, originally encompassed two additional control air
end users (two 5th vital battery room dampers) which were later
determined to have already been provided with air filters.
Installation of the filters fcr the MSIVs was verified by the
inspectors during a field walkdown.
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Initially, the installation ~
of the four MSIV filters was
considered acceptable to address the inspectors' concerns over the
lack of individual filters for safety-related components. A total
of 24 safety-related components had been identified in IR
! 327,328/92-34 as not having individual filters,18 of which were
! considered to be adequately protected due to their air being
provided from the more reliable and safety-related ACA system.
The four MSIVs and the two battery room dampers made up the
balance of the original 24. However, as discussed in paragraph
8.a. above, the ACA system has not passed an air quality test for
particulate since the water intrusion event in October 1992. That ,
l fact coupled with the historic problems of the control air system '
! overall, caused the inspectors to question the 18 components which
l were previously considered to be acceptable without filters
l because they were supplied by the ACA system. This item will ,
l remain open pending the licensee's resolution of the air quality l
!
l problems and a re-assessmat of the need to install filters in the
remaining 18 ACA systen supplied components. !
c. (Closed) LER 50-327,328/92-025, Containment Isolation Resulting l
From a loss of Control Air ;
! On December 15, 1992, a loss of nonessential control air pressure I
l resulted in components fai-ling to their loss of air position and a l
turbine runback from 100% power on both units. This event was
l caused by a failure of the air compressor sequence selector
l
switch. At the time, that switch had an outstanding maintenance
work request, but had not yet been replaced. For corrective
actions, the licensee replaced the air compressor sequence
selector switch; developed a list of degraded equipment with high-
risk potential to ensure proper prioritization of corrective
actions; and conducted a secondary plant reliability study to
determine critical components (single point instrumentation
component failures that alone could cause a unit trip or a
secondary side transient). Reliability Centered Maintenance (RCM)
,
personnel were reviewing the identified single point failure
components for potential revisions to the preventive maintenance
, program or design changes. The inspector reviewed one (of two)
l completed RCH reviews, on feedwater controls, which included
'
recommendations for modifications and increased calibration '
frequencies. The RCH review of single point failure components
was scheduled to be completed by December 1994. This LER is
closed.
9. Exit Interview
"
The inspection scope and results were summarized on July 2 and 23,1993,
with those persons indicated in paragraph 1. The inspectors described
the areas inspected and discussed in detail the inspection findings
listed below. Propriet uy information is not contained in this report.
Dissenting comments were not received from the licensee. The following
findings were discussed:
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Violation 50-327,328/93-32-01, for failure to follow procedures
! when no corrective action program document was written to identify
- the problem and no corrective actions were initiated after the air
j quality test did not meet acceptance criteria for particulate for !
- the safety related portion of the Control Air System (paragraph. '
l 8.a.). ,
( -
IFI 50-327, 328/93-32-02, to followup on licensee actions to *
- address weaknesses identified by the inspectors during the i
implementation of a modification (DCN-G-8937-B) which made piping
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changes to portions of _ the MFW system (paragraph 5.b.) i
10. Acronyms and Initialisms .
j ACA Auxiliary Control Air !
4 ACP Administrative Control Program l
!
ANSI American National Standards Institute ~ '
ASME American Society of Mechanical Engineers i
B0P Balance of Plant
j BRC Backlog Review Committee
l
1 CAQ Condition Adverse to Quality ;
CCW Condenser Circulating Water i
DCN Design Change Notice .
i E/C Erosion / Corrosion !
j FSAR Final Safety Analysis Report <
i
! GL Generic Letter i
- IFI Inspector Followup Item.
! II Incident Investigation
! INPO Institute of Nuclear Power Operations !
! IR Inspection Report i
j LER Licensee Event Report
4 MBCW Motor Bearing Cooling Water
i MIL Master issues List
i MOV Motor Operated Valve
MRRC Management Restart Review Committee
MSIV Main Steam Isolation Valve i
, MTI Maintenance Team Inspection l
t NOV Notice of Violation ;
i NPSH Net Positive Suction Head
[i
PER Problem Evaluation Report
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PM Preventive Maintenance
} PMT Post Modification Testing
j psig Pounds per Square Inch Gauge
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RCM Reliability Centered Maintenance
RH Relative Humidity
, RT Radiography Test
SCAR Significant Corrective Action Report
j SCSA Station Control and Service Air
j S/G Steam Generator
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SS Stainless Steel
SSP Site Standard Practice
SSPS Solid State Protection System
SWEC Stone and Webster Engineering Corporation
TACF Temporary Alteration Control Form
TFAR Trending Failure Analysis Report
TS Technical Specifications
TVA Tennessee Valley Authority
URI Unresolved Item
WO Work Order
WR Work Request
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