IR 05000309/1993014
| ML20024H959 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 08/17/1993 |
| From: | Lazarus W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20024H957 | List: |
| References | |
| 50-309-93-14, NUDOCS 9308310026 | |
| Download: ML20024H959 (11) | |
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U.S. NUCLEAR REGULATORY COMMISSION
REGION I
Report 93-14 License DPR-36 i
Inspection At:
Maine Yankee Atomic Power Plant
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Wiscasset, Maine (Maine Yankee Atomic Power Company)
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i Conducted:
June 10 through July 27,1993 Inspectors:
Charles S. Marschall, Senior Resident Inspector l
William T. glsen, Resident Inspectoi
//!f.5 Approved by:
W.[Idzards,) Chief, Reactor Project Section 3B Date SCOPE Resident inspection of operations, maintenance / surveillance, engineering / technical support, and plant support.
OVERVIEW i
Operations Maine Yankee continued to demonstrate safe, conservative plant operation during the report period. A detailed inspection of the Primary Component Cooling system revealed that it was in very good material condition and properly aligned. Plant staff promptly corrected a few minor discrepancies found by the inspectors. Operators properly monitored reactor coolant pump seal leakage and responded appropriately when the no. 3 reactor coolant pump lower seal failed. The control room operators promptly identified an abnormal valve operation when heater drain valve HD-A-180 would not close and responded quickly to prevent an unnecessary plant transient. The plant operators responded properly to station auxiliary transformer X-16 spurious deluge system actuation. Plant operators and maintenance electricians diligently tracked down a ground on electrical bus 12 and corrected a serious electrical hazard.
Maintenance and Surveillance Maintenance personnel properly controlled maintenance activities during the repair of air compressor C-1B and the new coil installation for valve LSI-F-59. The inspectors noted excellent supervision during the installation of alternate cooling piping for the spent fuel heat exchanger.
Engineering and Technical Support The cognizant engineer for the containment personnel hatch leak rate test demonstrated excellent knowledge of the plant procedure and technical l
specification acceptance criteria. The safety issue concern, issued in response to a Part 21 l
notification concerning limitorque actuator motor temperature problems, was comprehensive
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and appropriate.
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9308310026 930818 PDR ADOCK 05000309-G PDR
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(OVERVIEW CONTINUED)
Plant Suncort The Maine Yankee program of painting floors in the radiologically controlled area with epoxy based paint has resulted in significant long term improvement in controlling the spread of contamination. Security staff took timely action to control vehicular traffic and
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used a simple and adaptable means of achieving the desired results.
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TABLE OF CONTENTS t
i O V E R VI EW............................................... i'
TABLE OF CONTENTS.......................................iii
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1.
OPERATIONS
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1.1 Primary Component Cooling Water System Walkdown I
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1.2 Reactor Coolant Pump Imwer Seal Failure.................... 2 i
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1.3 Extraction Steam Isolation from First Point Heaters
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l.4 Transformer X-16 Spurious Deluge Actuation................... 4 1.5 Ground on 480V Bus 12............................... 4 i
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MAINTENANCE and SURVEILLANCE......................... 5 l
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ENGINEERING and TECHNICAL SUPPORT
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3.1 Personnel Containment Hatch Leak Rr': Testing
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3.2 Limitorque Valve Operator Temperatures..................... 6 l
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P LA NT S U P PO RT....................................... 6
4.1 Radiological Lontrols................................. 6 4.2 S ecu ri ty......................................... 7
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A D M I NI STRATI V E...................................... 7 l
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5.1 Persons Contacted................................... 7 5.2 Summary of Facility Activities........................... 7
5.3 Interface with the State of Maine.......................... 8 5.4 Exi t M eeting...................................... 8 j
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DETAILS 1.
OPERATIONS On a daily basis, inspectors verified adequate staffing, appropriate access control, adherence to procedures and Limiting Conditions for Operation, operability of protective systems, status of control room annunciators, status of radiation monitors, emergency power source operability, and operability of the Safety Parameter Display System (SPDS). Each week, the inspectors verified operability of selected Engineered Safety Features (ESF) trains and assessed the condition of the plant equipment, radiological controls, security and safety. The inspectors performed biweekly review of a safety-related tagout, chemistry sample results, shift turnovers, ponions of the containment isolation valve lineup, the posting of notices to workers and operability of selected ESF trains. The inspectors evaluated plant housekeeping and cleanliness.
1.1 Primary Component Cooling Water System Walkdown (71707)
During the inspection period, the inspectors performed a detailed walkdown of portions of the Primary Component Cooling Water System (PCC) components to verify their operability.
The inspectors verified that system lineup matched plant drawings and the as built configuration. They looked for equipment conditions that might degrade plant performance, such as incorrectly installed valves, gross packing leakage, bent stems, or missing handwheels. The inspectors verified that hangers and supports were correctly installed and maintained. In addition, the inspectors assessed cleanliness, housekeeping, and general system material condition.
Pro lure 1-15-1, Primary Component Cooling System, attachment A, PCC System Normal Valve Alignment, lists approximately five hundred valves. Plant personnel and the alignment procedure indicated that approximately three hundred valves in the system were located in the containment, high radiation areas, locked high radiation areas, or contaminated areas.
Since this inspection is a representative sample, and in the interest of keeping exposures As Low As Reasonably Achievable, the inspectors did not verify these component alignments.
The inspectors examined approximately two hundred of the remaining valves, associated piping, and other significant components in the PCC system.
l The alignment procedure indicated four valves in the Primary Auxiliary Building Lower Evaporator Cubicle for the P-11 recirculation evaporation reboiler cooler should be in the open position. The inspectors found valves PCC-349 through PCC-352 in the shut position, with Yellow Tag Order 91-033 controlling their position. The licensee removed the component from service, and therefore it no longer needed a PCC connection. The latest l
revision to the procedure, which the Plant Shift Supervisor (PSS) indicated was the controlling document, did not reflect this change. The PSS initiated a Temporary Procedure Change (TPC) to correct the procedure.
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Valve PCC-501, the DG-1 A supply vent, was found not locked in position as the procedure required. The PSS indicated that a complete system valve alignment had not been performed since the newest revision of the procedure had been issued, and that it was not necessary to lock this valve in position. The PSS also indicated that PCC had been continuously in
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service for approximately three years preceding the inspectors * discovery that the valve was not locked. The inspectors concluded that the valve had not been subjected to an alignment under control of the current revision of procedure 1-15-1. In addition, the counterpart valve j
on DG-1B was not required to be locked by pmcedure, and the inspectors found that procedure 1-15-1 did not require any other PCC vent valve outside of containment to be locked in position. In response to the inspectors questions, the licensee changed the procedure to remove the locking requirements. The inspectors noted that the vent line
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associated with PCC-501 was capped offering equivalent protection to locking the valve.
The inspectors found that all vent lines observed during the inspection were similarly capped,
and the isolation valves were closed. Failure to adhere to procedural requirements for locked l
valves was previously cited in NRC Inspection Report 50-309/93-03. In this instance, the inspectors concluded that the failure had no safety significance, and the failure to follow the procedure occurred several years prior to the instance noted in inspection report 50-309/93-03. The inspectors noted that the licensee's corrective action for the violation included reviewing all locked valve procedures. The licensee promptly changed the procedure to delete the locking requirement.
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With the exception of the two minor discrepancies above, which had no safety significance and the licensee promptly corrected, Maine Yankee generally maintained the PCC system in i
good condition. Based on the components inspected, the inspectors concluded the PCC l
system was capable of performing its intended function.
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1.2 Reactor Coolant Pump Lower Seal Failure On July 2 at 2:30 am, Maine Yankee control room operators determined from a review of control room logs and observation of control room instrumentation, that the no. 3 reactor coolant pump (RCP) lower seal was slowly degrading, based on observation that the pressure i
drop across the seal was decreasing. The Bentley-Nevada RCPs utilize Byron Jackson N-9000 seals. The N-9000 seals consist of four interchangeable seals arranged by stages within a seal cartridge assembly. Three high pressure seals are contained within the cartridge to provide primary sealing of the reactor coolant system (RCS). The fourth seal, called the vapor seal, is installed separately above the other three seals. The vapor seal minimizes leakage from the RCP, and serves as a backup. Each seal is designed to accept full RCS differential pressure. During normal operation, however, RCS pressure is distributed equally across each of the three seal stages. In the event that seal leakage increases across a seal stage, pressure differential across that seal stage decreases, and the remaining seal stages equally share the increased pressure. The lower seal is one of four stages in the pump seal assembly and is the first seal to be exposed to full reactor coolant system pressure.
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The gradual seal degradation continued until July 3, when more rapid deterioration began, i
The middle and upper seals functioned as designed to compensate for the lower seal failure.
High vibration and Loose Parts Monitoring System alarms for the no. 3 RCP and no. 3 Steam Generator also accompanied the seal failure. The alarms cleared after the seal stabilized with pressure distributed on the remaining seal stages.
i Plant engineering personnel assisted the control room operators in determining the safety implications of the failure and plan to make a root cause determination for the failure when
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the seal assembly replacement occurs during the up-coming outage.
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Maine Yankee demonstrated a strong safety perspective in identifying and monitoring the seal
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failure. Subsequent engineering personnel involvement in assisting the operators greatly aided in determining the proper course of action concerning pump operability and overall plant safety. The inspectors determined that Maine Yankee's actions were appropriate and i
that the reactor coolant pump seals could meet their intended safety function.
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1.3 Extraction Steam Isolation from First Point IIcaters On July 7, the licensee initiated gradual isolation of extraction steam from the first point j
heaters (E-II A and E-11B) to the low pressure section of the main turbine to increase j
electrical generation for end of cycle coastdown. During this evolution, the heater drain tank normal level control valve (HD-A-180) would not fully close. An instrumentation and controls (I & C) technician determined that the valve operator appeared to function normally, and that the valve was binding. As a result of the HD-A-180 failure, operators elected to isolate HD-A-180 to prevent a major feedwater transient. They shifted control of heater drain tank level to the high level dump valve (HD-A-188).
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Shifting to HD-A-188 required that an I & C technician adjust the valve to control level in the normal range. While the I & C technician adjusted the HD-A-188 valve controller, the valve went full open, heater drain pump P-62A tripped and a feedwater system oscillation occurred. The valve was designed as a dump valve, and did not operate well as a level control valve, however, as a result of the HD-A-180 failure, the licensee determined that use of HD-A-188 to control level was a appropriate to contml feedwater oscillations.
The feedwater system stabilized after restarting heater drain pump P-62A and returning control of the heater drain tank to normal level control valve HD-A-180. The evolution then proceeded as expected and the first point heaters were isolated. The faulty control valve will be repaired during the up-coming outage. The inspectors determined the licensee actions to be proper and rafe in response to the event.
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1.4 Transformer X-16 Spurious Deluge Actuation On June 10, the fire deluge system actuated for Station Auxiliary Transformer X-16. The Shift Supervisor sent an auxiliary operator to the transformer to investigate the problem. The auxiliary operator reported that the transformer was not on fire. Control room personnel entered Station Abnormal Operating Procedure (AOP) 2-37, Non-Safeguards Annunciators, and shut isolation valve FS-249, thereby stopping the deluge. Transformer X-16 was not in service at the time of the event and no effect on plant operation occurred.
The actuation of the transformer deluge system also automatically started the electric driven fire pump P-4. In accordance with station procedures, operators then stopped the pump and placed it in the automatic (standby) mode of operation to respond as required. The berm at the base of the transformer contained the deluge water. This investigation by plant personnel identified that the manual actuation handle for X-16, located outside the turbine building on the north wall, was in the actuated position. A plastic tie wrap normally holds the handle in the non-actuated position. No station personnel were in the area when the actuation occurred. Maine Yankee management concluded that the plastic tie wrap failed due to age, and gravity caused the handle to drop, actuating the deluge.
The inspector reviewed the response to the event and determined that Maine Yankee took timely and appropriate corrective action.
1.5 Ground on 480V Bus 12 On July 16, Maine Yankee control room operators observed intermittent electrical ground
alarms on the non-nuclear safety 480 volt electrical bus 12, power to the Circulating Water l
Pumphouse (CWPH). The station operator and maintenance electrical personnel promptly I
investigated. The electrical maintenance mechanic found a coil of cable energized with
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uninsulated lugs laying on the gmund outside the CWPH. This presented a serious personnel j
hazard, t 6 any person contacting the lug could have been fatally shocked.
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Maine Yankee station management directed a root cause analysis to be performed to investigate the event and requested that recommendations to prevent recurrence be developed.
During the investigation all employees involved with the main transformer replacement
project were interviewed and it could not be determined who plugged the power cable into the power pack after the cable was disconnected.
I The inspector reviewed the root cause determination and found it to be thorough and provide excellent recommendations to prevent recurrence of this type of problem in the future.
Maine Yankee demonstated an improved root cause effort to resolve this problem with an in depth and thorough analysis of the situation during the main transformer work effort and l
reasona51e conclusions.
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2.
MAINTENANCE and SURVEILLANCE The inspectors observed and reviewed maintenance and problem investigation activities to verify compliance with regulations, administrative and maintenance procedures, work order (WO) requirements, codes and standards, proper QA/QC involvement, safety tag use, equipment alignment, jumper use, personnel qualifications, radiological controls for worker protection, retest requirements, and reportability per Technical Specifications. The inspectors observed portions of the following activities:
WO 93-1617, Calibrate PFD1 and PFD2 Time Delay Relays;
WO 93-2136, Failure of Air Compressor C-1B; WO 93-0199-02, Install Alternate Cooling to Spent Fuel Pool Heat Exchanger E-25;
WO 92-6882, Install New Coil for LSI-F-59; Procedure 3-1-2, Revision 47, ECCS Routine Testing;
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Procedure 1-4-2, Revision 6, Power Ixvel Control;
Procedure 3.17.4.6, Revision 16, Personnel Air Ink Leak Test; and
Procedure 3.17.4.1, Revision 13, Purge Exhaust Duct Ieak Test.
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The inspectors observed that Maine Yankee staff performed these routine maintenance and j
surveillance activities safely and in compliance with regulatory and licensee requirements.
j The inspectors noted that the presence and use of work packages and procedures has improved significantly during the present operating cycle. The inspectors also observed improved performance in considering the impact of maintenance and surveillance activities on equipment operability requirements.
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ENGINEERING and TECIINICAL SUPPORT 3.1 Personnel Containment IIatch Leak Rate Testing The inspectors reviewed Maine Yankee procedures 3.17.4, Type B & C Irakage Testing, and 3.17.4.6, Personnel Air Lock Irak Test, to determine compliance with 10 CFR 50, Appendix J, and Technical Specification (TS) 4.4, Containment Testing. The procedures I
meet the requirements of Appendix J and technical specifications. To perform the test, f
Maine Yankee personnel verified adequate hydraulic pressure on the 84-inch hatch closing mechanism to ensure proper closure force, examined the O-ring seals for damage, and pressurized the volume between the innt and outer hatch doors to 60 psig. After ihe hatch temperature and pressure stabilized, engineering department personnel measured pressure decay to calculate leak rate. Technical Specification 4.4 limited acceptable leakage from the containment personnel hatch to less than 30.0 pounds-mass / day (lbm/ day) at 55 pounds per square inch gage (psig). After the test on July 8,1993, the leakage rate was 1.20 lbm/ day at 55 psig, well within the acceptance criteria of TS 4.4.
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The inspectors also examined and verified calculations for the personnel air lock leak test.
The licensee performs this test after every containment entry (generally once every two
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weeks during power operations). The inspectors determined that the calculations were l
complete and accurate. The inspectors also found that the responsible engmeer was knowledgeable of regulatory and technical requirements for the tests.
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3.2 Limitorque Valve Operator Temperatures
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On July 6, Maine Yankee engineering personnel presented Safety Issue Concern (SIC)
!93-003 to station management. The SIC identified that, under certain circumstances, a safety related motor operated valve may not develop the required torque due to elevated motor temperature. This situation could occur during a valve surveillance, when a single valve is j
stroked for testing followed by a loss of Coolant Accident (LOCA). In the event that the Recirculation Actuation System (RAS) initiates, coincident with the worst case degraded voltage situation within 15 minutes of the initial valve.;troke, the motor operator might not develop sufficient torque.
The temperature problem was limited to certain Reliance motors supplied with Limitorque actuators installed on safety related valves. Maine Yankee's preliminary examination identified eight valves susceptible to the problem, and recommended that valves LSI-M JO and LSI-M-41 be considered degraded for 10 minutes after operation. The evaluation determined that the other valves were not susceptible to the postulated events. The
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operations department initiated a temporary procedure change to procedure 3-1-2.3, ECCS Routine Testing - Valve Testing and Position Verification, to add a 15 minute wait between valve strokes. Plant management concluded the delay between successive valve strokes I
adequately minimized the chance of valve motor operator temperature degradation. Mame Yankee planned to replace the affected valve operators with increased torque capacity motor
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operators during the upcoming outage to eliminate this problem. The inspectors concluded
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that engineering demonstrated appropriate safety perspective in identifying the motor operator vulnerability. The inspectors also noted that engineering personnel promptly brought this concern to the attention of operations management; Maine Yankee's efforts to improve this aspect of engineering performance have been effective in this instance. In addition, i
operations management response was timely and effective.
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PLANT SUPPORT 4.1 Radiological Controls Inspectors routinely reviewed radiological controls including Organization and Management, external radiation exposure control and contamination control. The inspectors also monitored standard industry radiological work practices, and conformance with radiological control procedures and 10 CFR 20 requirements. No problems were noted during the inspection period. The inspectors noted that the radiological protection staff continued to reduce
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contamination throughout the plant. The inspectors noted that the licensee's program of
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painting floors in the radiologically controlled arca with epoxy based paint has resulted in j
significant long term improvement in controlling the spread of contamination.
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4.2 Security
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The inspectors verified that security conditions met regulatory requirements and the
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requirements of the physical security plan, and complied with approved procedures. The checks included security staffing, protected and vital area barriers, vehicle searches and I
personnel identification, access control, badging, and compensatory measures when required.
No discrepancies were identified.
4.2.1 Vehicular Traffic Control
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I During the inspection period, the licensee installed additional measures to insure adequate control of vehicular traffic outside the protected area. The licensee implemented the measures in response to information provided by the NRC, as a means of precluding the potential for vehicular traffic impacting security of the protected area. The inspectors determined that the measures provided an effective means of achieving vehicular control. In
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addition, the inspectors noted that Maine Yankee took timely action in response to the information provided, and that the method used was a simple and adaptable means of
achieving the desired results.
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ADMINISTRATIVE 5.1 Persons Contacted
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During this report period, inspectors conducted interviews and discussions with various licensee personnel, including plant operators, maintenance technicians and the licensee management.
5.2 Summary of Facility Activities Maine Yankee operated at 99 percent power at the beginning of the inspection period on June 10, beginning end of cycle coastdown. At the end of the inspection period, July 27, reactor power reached 80 percent. Coastdown proceeded as planned, with the exception of the seal failure noted in Section 1.2.
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Other inspections conducted during this inspection period included a Radiological Environmen>1 Monitoring and Radiological Lffluent Control Programs inspection conducted from June ? t.nough 18 by Ms. L. Peluso and Dr. J. Jang, an inspection of In-Service
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Testing, conducted June 28 through July 2 by Messrs. T. Kenny, J. Yerokun, and R. DePriest, and an inspection of RadWaste and Transportation, conducted June 28 through July 2 by Mr J. Furi. -_
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5.3 Interface with the State of Maine Periodically, the resident inspectors and the onsite representative of the State of Maine
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discussed findings and activities of their corresponding organizations. No unacceptable plant conditions were identified.
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5.4 Exit Meeting
Inspectors periodically held meetings with senior facility management to discuss the j
inspection scope and findings. At the conclusion of the inspection, the inspectors also presented a summary of findings for the report period.
During the inspection period the inspectors conducted backshift inspection on June 10,17, 29, 30, and July 1. The inspectors also conducted deep backshift inspection on July 2 and 4.
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