IR 05000528/1997006
| ML17312B548 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 06/27/1997 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML17312B546 | List: |
| References | |
| 50-528-97-06, 50-528-97-6, 50-529-97-06, 50-529-97-6, 50-530-97-06, 50-530-97-6, NUDOCS 9707080388 | |
| Download: ML17312B548 (30) | |
Text
ENCLOSURE 2 U.S. NUCLEAR REGULATORY COMMISSION
REGION IV
Docket Nos.:
License Nos.:
Report No.:
Licensee:
Facility:
Location:
Dates:
Inspectors:
Approved By:
50-528 50-529 50-530 NPF-41 NPF-51 NPF-74 50-528/97-06
'0-529/97-06 50-530/97-06 Arizona Public Service Company Palo Verde Nuclear Generating Station, Units 1, 2, and 3 5951 S. Wintersburg Road Tonopah, Arizona May 4 through June 14, 1997 D. Orsini, Resident Inspector D. Carter, Resident Inspector B. Olson, Project Engineer D. Acker, Senior Project Engineer D.'Corporandy, Project Engineer Dennis F. Kirsch, Chief, Reactor Projects Branch F Attachment:
Supplemental Information 9707080388 970627 PDR ADQCK 08000828
EXECUTIVE SUMMARY Palo Verde Nuclear Generating Station, Units 1, 2, and 3 NRC Inspection Report 50-528/97-06; 50-529/97-06; 50-530/97-06
~Oerations Control room operators responded promptly and effectively to the Unit 1 reactor trip and management developed a good plan for unit restart (Section 01.1).
The licensee's response to the Unit 3 reactor trip was good.
The event was correctly categorized and the NRC was promptly notified. Control room operators properly performed emergency procedures and stabilized the plant.
Troubleshooting efforts effectively established the cause of the trip (Section 01.2).
The inspectors identified improper locking device installations on three valves.
Although the valves were in their required position, the failure to properly install locking devices on the valves was the first example of a violation of Technical Specification (TS) 6.8.1, for failure to follow approved procedures (Violation 50-528;530/97006-01)
(Section 02.1).
The inspectors identified a normally locked open valve that had been repositioned and was not properly documented.
Although the status of the Auxiliary Feedwater (AFW) Pump N discharge valve was controlled by the licensee's equipment clearance process, the failure to document the valve in accordance with the locked valve procedure was the second example of a violation of TS 6.8.1, for failure to follow approved procedures (Violation 50-530/97006-01)
(Section 03.1).
NRC concerns regarding Operations staffing resulted in a licensee evaluation that identified three occasions where minimum auxiliary operator (AO) staffing was not in compliance with an approved procedure, and was the third example of a violation of TS 6.8.1, for failure to follow approved procedures (Violation 50-529/97006-01)
(Section 06.1).
Maintenance Heating, ventilation, and air conditioning (HVAC) technicians demonstrated good judgement by stopping work during the adjustment of essential chilled water pump packing, and involving engineering, when acceptable seal leakage could not be obtained (Section M1.2).
The inspector concluded that maintenance personnel performed well in locating and correcting the problem with the Unit 3 Steam Generator 1 downcomer line (Section M1.3).
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Re ort Details Summar of Plant Status Unit 1 began this inspection period at 100 percent power.
On May 27, the unit experienced a reactor trip when 13.8 Kv electrical Bus NANS01 load shed due to a faulty fuse in the potential transformer circuitry. On May 30, the unit conducted a reactor startup and power ascension.
On June 1, the unit returned to 100 percent power and remained there for the duration of the inspection period.
Unit 2 remained at essentially 100 percent power throughout this inspection period, with the exception of a power reduction to 60 percent on June 9 for repairs on the Train 2A low pressure heater.
Unit 3 began this inspection period at 100 percent power.
On May 31 the unit experienced a reactor trip while troubleshooting a problem on the plant protection system.
On June 2, the unit stabilized at 35 percent power in order to repair the Steam Generator
downcomer check valve (Section M1.3).
On June 5, the unit returned to 100 percent power and remained there for the duration of the inspection period.
I. 0 erations
Conduct of Operations 01.1 Unit 1 Reactor Tri a 0 Ins ection Sco e 71707 92901 On May 27, 1997, Unit 1 experienced a reactor trip due to a load shed on electrical Bus NANS01 that was caused by a degraded fuse in the potential transformer circuitry. The inspectors responded to the site and observed control room operators (CROs) respond to the event.
In addition, the inspectors observed the management review team and plant review board meetings prior to restart.
b.
Observations and Findin s The control room staff had observed an indicated degraded voltage on the 13.8 Kv electrical bus, NANS01.
Bus NANS01 subsequently shed the power loads.
Both Trains 1A and 2A reactor coolant pumps were lost, and the reactor tripped due to a generated trip signal, low departure from nuclear boiling ratio.
The CROs responded effectively to the trip and stabilized the plant in Mode 3, the hot standby condition.
The classification of the trip and the notifications to offsite organizations were made in a timely manner.
The management review team developed restart issues that were to be completed prior to restarting the plant.
The inspector determined that the restart issues list was complete and included the requirement to have the selected operating crews attend a training session to review and simulate the restart procedure t
-2-Engineering investigations determined that the Phase C fuse in the potential transformer circuitry had developed a high impedance, creating a degraded voltage condition which actuated the load shed relay circuit.
C.
Conclusion CROs responded promptly and effectively to the Unit 1 reactor trip and management developed a good plan for unit restart.
01.2 Unit 3 Reactor Tri a 0 Ins ection Sco e 71707 92901 On May 31, 1997, Unit 3 experienced a reactor trip during instrumentation and control troubleshooting of a recurrent spurious opening of reactor trip switchgear Breakers A and C. The inspectors responded to the site and reviewed the circumstances of the trip, discussed events of the trip with unit operators and management personnel, and reviewed CRO logs and key plant parameter trends.
b.
Observations and Findin s The inspectors determined that the CROs had performed the standard posttrip actions, classified the event as an uncomplicated reactor trip, and implemented the reactor trip emergency operations procedures.
Troubleshooting activities were stopped and the area was quarantined.
The licensee made the required 4-hour notification of the reactor trip to the NRC Operations Center in a timely manner.
The inspector attended the management review team meeting which discussed the circumstances of,the trip and corrective actions needed to be taken prior to reactor restart.
The licensee evaluated why all four (both trains Rx trip breakers)
had opened when the troubleshooting was only associated with reactor trip switchgear Breakers A and C.
Upon further investigation it was determined that a jumper around a spare reactor trip contact in Breaker Logic B and D, which should have been installed during construction, was missing and two loose terminal lugs within the same logic matrix of the plant protection system were found, which, in combination with the missing jumper, caused a loss of power to the relays that keep the reactor trip switchgear breakers energized..The licensee initiated Condition Report Disposition Request (CRDR) 370263 to determine the root cause and transportability of the event.
The licensee verified that the jumper was installed correctly in Units 1 and 2. This issue will be reviewed in greater depth during the resolution of LER 50-530-9700 ]
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Conclusion The licensee's response to the Unit 3 reactor trip was good.
The event was correctly categorized and the NRC was promptly notified.
CROs properly performed emergency procedures and stabilized the plant.
Troubleshooting efforts effectively established the cause of the trip.
Operational Status of Facilities and Equipment 02.1 Im ro er Valve Lockin Device Installation a.
Ins ection Sco e 71707 The inspectors performed a general system walkdown and conducted discussions with licensee personnel to assess the condition of the AFW pump equipment rooms in Units 1 and 3.
b.
Observations and Findin s The inspectors noted that drain Valves AFA-V087 and AFA-V075, located in the Unit 3 turbine-driven AFW pump room, were identifi ified to be included in the locked valve program.
The inspector observed that the valves did not appear to have been locked properly; the wire cable was installed too loosely to preclude turning the T-style valve handle a number of turns without breaking the locking cable seal.
The locking method used was a wire cable attached to the labeling tag, then wrapped around the valve and held together with a breakable seal.
The valves were required to be in the locked closed position.
The inspectors also observed a
similar condition on a drain valve in the Unit 1 AFW pump room; The inspectors reviewed the licensee's locked valve Procedure OAC-OZZ06,
"Locked Valve, Breaker, and Component Control," Revision 11, and noted that paragraph 3.1.5 states, in part, that the tag shall be attached with wire cable, and a sealing device shall be attached to the cable to prevent its manual operation.
An attachment to the procedure included a visual example of the proper locking method; however, the T-style valve handles are not shown.
The inspectors discussed the observations with the Unit 3 shift supervisor (SS).
The SS agreed that the identified valve locking devices were not installed consistent with the procedure and had the installations corrected.
The licensee performed a subsequent walkdown in all three units.
Several valves were identified as not being consistent with the procedure.
The shift supervisor (SS) initiated CRDR 370228 to address this issue and requested a
change to the procedure to provide additional guidance for the proper method of locking these types of valves.
In addition, the licensee stated that they determined
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that all the valves were found to be in their required positions.
Since all the valves were found in their proper positions, the inspectors concluded that this individual item was of low significance.
C.
Conclusion The inspectors identified improper locking device installations on three valves.
Although the valves were in their required position, the failure to properly install locking devices on valves was the first example or a violation of TS 6.8.1; for failure to follow approved procedures (Violation 50-528;530/97006-01).
Operations Procedures and Documentation 03.1 Failure to Pro erl Track Locked Valve Unit 3 a 0 Ins ection Sco e 71707 On June 3, the inspector reviewed the equipment clearance order for the work activity associated with the replacement of the Steam Generator 1 downcomer check valve and had discussions with the control room staff.
b.
Observations and Findin s The inspector noted that the discharge valve for AFW Pump N was required to be tagged in the closed position.
The valve was a normally locked open valve and was controlled in accordance with the licensee's locked valve program.
The inspector reviewed the locked valve and breaker control book and identified that the valve's reposition was not documented.
Procedure 40DP-9OP19, "Locked Valve, Breaker and Component Tracking," requires proper documentation prior to breaking the locked seal and repositioning the valve.
The inspector discussed this observation with the control room supervisor (CRS).
The CRS could not find any documentation justifying the position of this valve and initiated the proper documentation, in addition to a CRDR.
C.
Conclusion The inspectors identified a normally locked open valve that had been repositioned and was not properly documented.
Although the status of the AFW Pump N discharge valve was controlled by the licensee's equipment clearance process, the failure to document the valve in accordance with the locked valve procedure was the second example of a violation of TS 6.8.1, for failure to follow approved procedures (Violation 50-530/97006-01).
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Operations Organization and Administration 06.1 Minimum AO Staffin a 0 Ins ection Sco e 71707 I
The inspector identified that operations had not provided clear expectations for AO shift manning requirements and documented the findings in NRC Inspection Report 50-528;529;530/96-18.
The licensee, in response to NRC's concerns, evaluated their compliance with AO staffing.
The inspector reviewed the conclusions of the evaluation.
b.
Observations and Findin s The licensee performed an investigation that included a 10 percent sample of shift coverage for a period of 6 months.
The investigation identified three examples that had existed where the minimum shift coverage for AO's was not being met.
In addition, the licensee determined that there were no instances found where AOs were unable to respond to any one unit because they were providing coverage for another unit.
The TS requirement for minimum shift coverage of AO's is two. However, Procedure 40DP-9OP02, "Conduct of Shift Operations," states that the minimum staff requirements for AOs is four per unit.
On three separate occasions, there were only three AOs on shift for one unit. The staffing sheet, which lists the individuals assigned for the operations crew on shift, had an individual assigned twice to the position of an AO, which resulted in only three AO's on shift.
The licensee's corrective actions included a revision to the conduct of the shift operations procedure and newly created operations department practices, which provide additional guidance for maintaining minimum shift manning requirements.
Training was planned to be provided to the site shift managers as well as the SSs.
Conclusions Operations staffing concerns resulted in an investigation that identified three separate occasions where minimum AO staffing was not in compliance with an approved procedure and was the third example of a violation of TS 6.8.1, for failure to follow approved procedures (Violation 50-529/97006-01).
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-6-II. Maintenance M1 Conduct of IVlaintenance M1.1 General Comments on Maintenance Activities a.
Ins ection Sco e 62707 The inspectors observed portions of the following work activity:
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WO 801303:
repair crosshead damage on charging pump A (Unit 1)
b.
Observations and Findin s The repairs to th'e charging pump had been included as a restart issue for Unit 1, following the plant trip. The inspector found the work performed to be professional and thorough.
The maintenance technicians were knowledgeable of their assigned task and supervisors and maintenance engineering were monitoring the conduct and progress of the activities.
M1.2 Re ack of Essential Chilled Water Pum
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Unit 3 a.
Ins ection Sco e 62707 On May 29, 1997, the inspectors observed HVAC technicians perform portions of the work involving the repair of the leaking gland seal on essential chilled water Pump B. The inspectors reviewed the work package and verified the equipment clearance order.
b.
Observations and Findin s The inspectors determined that the work package and the clearance tagout was adequate for the work activity performed on chilled water Pump B. The HVAC technicians demonstrated adherence to and a good understanding of the work package.
Upon completion of the pump repack, the CROs were properly notified and the system was'then filled and vented.
During the subsequent pump start, the HVAC technicians attempted to adjust the packing to within acceptable leakage specifications (30-60 drops per minute).
The technicians proactively monitored the packing gland for overheating while tightening the packing gland retaining nuts.
However, they were unable to get the leakage within specification.
The pump packing was subsequently removed for inspection by engineering and maintenance representatives.
The original packing, specified by the vendor, had been discontinued because of asbestos content.
The packing that had been
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-7-removed from the pump gland was a graphite yarn filament type.
Although this packing was specified as an acceptable alternative by the vendor, the HVAC technicians experienced problems in cutting the packing, due to the tendency of the cut ends to fray and unravel, thus, not forming a good seal.
The licensee generated a Deficiency Work Order (DFWO) 801678, to allow the replacement of the graphite yarn filament packing material with an alternate type.
The new type packing does not exhibit the same problems when it is cut as did the old packing.
On May 30, the pump was repacked with the new type of packing and an acceptable amount of seal leakage was achieved.
The pump was placed back in service on May 31.
C.
Conclusions HVAC technicians demonstrated good judgement by stopping work and involving engineering when acceptable seal leakage could not be obtained.
M1.3 Re lacement of Dama ed Check Valve Unit 3 aO Ins ection Sco e 62707 The inspector examined troubleshooting activities associated with the Steam Generator 1 downcomer control valve and observed the work performed on the upstream downcomer check valve, which corrected the problem.
Disassembly and inspection of the check valve was performed under Work Order 00801811
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b.
Observations and Findin s On June 2, during power ascension, following the Unit 3 plant trip, operations personnel identified that the Steam Generator 1 downcomer control valve was at the full open position.
The expected position for the power level at the time was approximately half open.
After obtaining flow
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measurements, the licensee determined that a flow restriction existed on check Valve 3PSGNV431.
The inspector observed maintenance personnel disassemble the check valve.
The maintenance technicians were careful to record and preserve the as-found condition of the valve.
Once the valve was disassembled, the licensee identified that the spring pin, which served to restrict axial movement of the hinge pin, had sheared, allowing sufficient movement of the hinge pin, which prevented free rotation of the check valve disc.
Further inspection of the check valve identified that a portion of the valve seat had been gouge I
-8-The licensee determined that the option to replace the valve was the most conservative.
The inspector observed the prejob briefing to perform the replacement of the check valve.
The briefing involved maintenance, operations, and engineering personnel.
The inspector determined that the briefing was thorough and had discussed the milestones, hazards, and conservative precautions, such as restricting personnel access from surrounding areas during the valve replacement.
Once the damaged check valve was removed and preparation of the weld ends were complete, the licensee measured the gap between the piping and replacement check valve and noted that it exceeded the welding specification, as well as the licensee's table, of acceptable cold spring gap.
Engineering performed a timely evaluation to demonstrate the feasibility of cold springing the line by an amount represented by the measured excess gap.
The licensee also performed a loose parts evaluation and concluded that no damage occurred.
The licensee concluded that the problem with the check valve disc interference was unique to check Valve 3PSGNV431, because it was the only check valve which utilized the spring pins to restrain axial motion of the'hinge pin. The similar valve on the other Unit 3 train, and the similar valves in Units 1 and 2, had hinge pins which were machined and press fitto prevent axial movement.
At the close of the inspection period, the licensee was continuing to determine the cause of the gouge in the check valve seat.
c.
Conclusions The inspector concluded that maintenance personnel performed well in locating and correcting the problem with the Unit 3 Steam Generator 1 downcomer line.
M1.4 General Comments on Surveillance Activities a.
Ins ection Sco e 61726 The inspectors observed all or portions of the following surveillance activities:
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Charging Pump Operability Test
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MSIVs,- Inservice Test b.
Observations and Findin The inspectors found these surveillances were performed acceptably and as specified by applicable procedure II i
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-9-MS Miscellaneous Maintenance Issues (92902)
M8.1 Closed Ins ection Followu Item IFI 50-530 94020-03:
application of Regulatory Guide 1.108 regarding valid tests and failures.
This item was opened after the inspectors were informed that the licensee would interpret Regulatory Guide 1.108 as not specifying the inclusion of all diesel generator tests in the overall number of tests for the purpose of determining test frequency following test failures.
The inspectors noted that the licensee's procedures required that all diesel generator tests be recorded so that all information was available for determining test frequency should test failures occur.
The inspectors also noted that the licensee's interpretation of Regulatory Guide 1..108 was not reflected in procedures, The inspectors, through discussions with NRR, concluded that the licensee's interpretation was incorrect; however, it did not result in a change to the frequency of diesel tests because there had been no recent test failures at Palo Verde.
The licensee was informed of the inspector's conclusion, and the licensee indicated that procedure changes would not be required as a result, of the NRC's position.
III. En ineerin ES Miscellaneous Engineering Issues E.8.1 Closed Violation 50-529 95010-02:
containment spray TS violation due to unrecognized valve failure. A containment spray pump mini-recirculation isolation motor operated valve (MOV) failed to stroke closed during testing.
After the valve was reopened, it stroked closed, so the licensee signed the test results as satisfactory.
No troubleshooting was accomplished.
Two weeks later the valve again failed. The licensee determined that the valve had an old style packing which was binding, that the MOV had been inoperable for longer than the TS action statement, and that review of the MOV operating traces would have identified a change in valve performance.
The licensee corrective actions included removing the old style packing from all similar valves and making administrative improvements in
'he MOV program, including requiring review of'valve operating traces.
The inspector reviewed the records of the packing replacement and the administrative improvements in'the MOV program documents.
The inspectors considered the licensee actions to have adequately resolved the violation.
E.8.2 Closed Licensee Event Re ort LER 50-529 95001-00:
containment spray TS violation due to unrecognized valve failure. This LER was reviewed in conjunction with Violation 50-529/95010-02 discussed in Section E.8.1 above.
E.8.3 Closed Followu Item'0-530 95025-04:
problems with moderator temperature coefficient test.
An SS noted during a moderator temperature coefficient test that control element assemblies (CEAs) were positioned below the rod insertion limits in the associated procedure.
The licensee raised the CEAs to be within the rod insertion limits. The followup item was opened to review the licensee's corrective
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The licensee's root cause evaluation determined that the CEAs had been within the actual insertion limits and the procedure limits were in error.
The licensee determined that the error was caused by attempting to provide a graph using word processing software, which did not provide the required accuracy.
Licensee corrective actions included using a graphics software program to generate new graphs and a briefing of operators on the need to insure that reactivity procedure limits were maintained.
The inspectors reviewed the licensee's actions and noted that the licensee had not addressed why personnel had missed the incorrect graph during procedure preparation and approval and discussed management oversight of reactivity issues with the licensee.
The licensee acknowledged that the initial review did not address human performance issues associated with review and issue of the procedure with the incorrect chart and noted that they had recently initiated a new program for reactivity management.
The inspectors reviewed the program and concluded that this program provided the basis for enhanced management oversight of reactivity control.
The licensee actions were adequate to resolve the followup item.
IV. Plant Su ort R1 Radiological Protection and Chemistry Controls R1.1 Radioactive Material Found Outside Radiolo ical Controlled Area RCA Ins ection Sco e 71707 On June 4, the licensee informed the inspectors that a pallet of unlabeled contaminated lead blankets was found outside the Unit 3 auxiliary building inside the RCA, and the truck used to transport the lead blankets was found to be contaminated in an area outside the RCA. The inspector discussed with licensee radiological protection management the sequence of events surrounding the situation.
b.
Observations and Findin s The licensee took immediate corrective actions to contain the contaminated material and performed surveys to determine the spread of the contamination.
Upon further investigations, the licensee determined that the event occurred back on May 20, 1997, during a transport of equipment from Unit 1 to Unit 3. The truck was found outside the RCA, however, it was contained within the protected area.
The licensee initiated a CRDR and began an investigation to determine the root cause of the event.
The inspectors willreview the licensee's evaluation, conclusions, and corrective actions during a future inspection (Unresolved Item 50-528;530/97006-02).
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Conclusion The licensee discovered unlabled lead blankets in the Unit 3 RCA yard that were contaminated.
In addition, the truck used to transport the lead blankets from Unit 1 to Unit 3 was located outside the RCA, but within the protected area, and determined to be contaminated.
This issue demonstrated a weakness in radiological controls and is an unresolved item.
V. IVlana ement Meetin s X1 Exit Meeting Summary The inspectors presented the inspection results to members of licensee management at the conclusion of the inspection on June 12, 1997.
The licensee acknowledged the findings presented.
The inspectors asked the licensee whether any material examined during the inspection should be considered proprietary.
No proprietary information was identifie ATTACHMENT PARTIAL LIST OF PERSONS CONTACTED Licensee P. Brandjes, Department Leader, Electrical Maintenance Engineering R. Flood, Department Leader, System Engineering R. Fullmer, Director, Nuclear Assurance M. Hypse, Section Leader, Electrical Maintenance Engineering W. Ide, Vice President, Nuclear Engineering K. Jones, Section Leader, Design Engineering D. Kanitz, Engineer, Nuclear Regulatory Affairs A. Krainik, Department Leader, Nuclear Regulatory Affairs J. Levine, Senior Vice President, Nuclear D. Mauldin, Director, Maintenance G. Overbeck, Vice President, Nuclear Production T. Radke, Director, Outages F. Riedel, Department Leader, Operations Standards C. Seaman, Director, Emergency Services M. Shea, Director, Radiation Protection D. Smith, Director, Operations J. Taylor, Unit 3 Operations Department Leader M. Windsor, Section Leader, Mechanical Maintenance Engineering INSPECTION PROCEDURES USED 71707 92901 62707 92902 Plant Operations Plant Operations Follow up Maintenance Observations Maintenance Follow up
~Oened 50-529;50-529; 50-530/97006-01 50-529;50-529; 50-530/97006-02 ITEMS OPENED CLOSED AND DISCUSSED VIO three examples of operations personnel failing to follow administrative procedures URI uncontrolled radioactive material located outside RCA Closed 50-529/95010-02 VIO 50-529/95001-00 LER 50-530/95025-04 IFI 50-530/94020-03 IFI containment spray TS violation containment spray TS violation problems with moderator temperature coefficient test application of RB 1.108 regarding EDG testing
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-2-LIST OF ACRONYMS USED AFW auxiliary feedwater AO auxiliary operator CEA control element assemblies CRDR condition report/disposition request CRS control room supervisior CRO control room operator HVAC heating, ventilation, and air conditioning IFI inspection followup item LER Licensee Event Report MOV motor-operated valves RCA raiological controlled area SS shift supervisor SSM site shift manager TS URI VIO Technical Specifications unresolved item violation
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