IR 05000309/1986015
| ML20213G111 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 11/06/1986 |
| From: | Lester Tripp NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20213G033 | List: |
| References | |
| 50-309-86-15, NUDOCS 8611170330 | |
| Download: ML20213G111 (10) | |
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U.S. NUCLEAR REGULATORY COMMISSION
REGION I
Docket / Report: 50-309/86-15 License:
DPR-36 Licensee:
Maine Yankee Atomic Power Company 83 Edison Drive Augusta, Maine 04336 Facility:
Maine Yankee Atomic Power Plant Inspection At: Wiscasset, Maine Dates:
September 11 - October 22, 1986 Inspectors:
Cornelius F. Holden, Senior Resident Inspector Je frey bertson, Resident Inspector Approved:
M l'/dr
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G. Tripp// Chief, Reactor Projects Section 3A
'Dite Summary:
Inspection on September 11 - October 22, 1986 (Report No. 50-309/86-15)
Areas Inspected:
Routine resident inspection (239 hours0.00277 days <br />0.0664 hours <br />3.95172e-4 weeks <br />9.09395e-5 months <br />) of the control room, accessible parts of plant structures, plant operations, radiation protection, physical security, fire protection, plant operating records, maintenance and sur-veillance.
Results:
One violation in the security area was noted and is considered signifi-cant because of the three examples.
Replacement of the #2 Main Feedwater Regulat-ing Valve primary controller was well planned.
8611170330 e61113 PDR ADOCK 05000309 O
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DETAILS 1.
Persons Contacted Within this report period, interviews and discussions were conducted with various licensee personnel, including plant operators, maintenance technicians and the licensee's management staff.
2.
Summary of Facility Activities The plant was operating at 100% power from the beginning of this report period until October 9, when a planned 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> power reduction to 75% was initiated.
The power reduction was initiated to perform maintenance on "D" Traveling Water Screen, #2 Main Feedwater Regulating Valve and for Turbine Valve testing.
The plant was returned to 100% power on October 12.
The reactor was manually tripped on October 19 to prevent equipment damage caused by induced current in the main transformer isophase bus ducts (details in section 9).
Repairs were completed and a startup was performed the same day. The plant was re-turned to 100% power on October 21 and remained there through the end of the report period.
3.
Followup on Previous Inspection Findings a.
(Closed) Temporary Instruction 2500/69 - Inspection of Response to IE Bulletin 85-01.
The licensee's actions in response to IEB 85-01 and TI 2515-67 have been documented in NRC Inspection Report 50-309/86-03.
Although previously inspected, the following is to document the addi-tional inspection findings required by TI 2500/69.
The procedures required by IEB 85-01, to perform periodic monitoring of Auxiliary Feedwater System temperature, and to recover from a steam binding event were properly approved prior to implementation.
Up-to-date procedures are available for use in the control room and auxiliary operator work stations.
Discussions with control room and auxiliary operators verified their use and understanding of the procedures.
b.
(Closed) Unresolved Item (50-309/85-28-01).
Licensee identified defi-ciencies in Surveillance Procedures, as a result of the efforts of the Interface Review Subcommittee for the Special Functional Testing (SFT)
Program.
These deficiencies resulted in failure to perform Technical Specification required surveillance testing for the specified functions of Table 4.1-1,2 and 3.
This item was unresolved pending completion of corrective actions.
The recommendations of the Interface Review Subcommittee Report were verified to be incorporated into the appropriate I & C and Operations Department Procedures.
The procedure revisions contained references to the SFT requirements and were reviewed and approved by PORC.
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(Closed) Inspector Follow Item (50-309/85-30-01).
Protection of Under-c.
ground Primary and Secondary Component Cooling System Piping From Corro-sion.
The original passive cathodic protection system uses sacrificial anodes of magnesium.
The licensee's inspection of these anodes found corroded and broken leads at the connections on the piping providing little or no protection.
The leads are being replaced using a different type of connection that is believed to be more corrosion resistant to provide immediate protection.
Platinum probes will be placed in the ground and an impressed current system will be installed.
The impressed current system provides a higher degree of protection against corrosion and a means to monitor current flow from the probes to the piping, an indication of effectiveness.
d.
(Closed) Inspector Follow Item (50-309/85-33-01). Measurement Control Evaluation - Nonradiological Chemistry. During inspection 85-33, the spent fuel pool, raw water and condensate were sampled for analysis.
Duplicate samples were sent to the Brookhaven National Laboratory (BNL)
for independent verification of analysis.
On completion of the analyses of water samples by the licensee and Brookhaven National Laboratory, a statistical evaluation was to be made.
These actions were completed.
Although there was some disagreement between the sample results it was determined to be the result of evaporation of the BNL samples.
4.
Routine Periodic Inspections a.
Daily Inspection During routine facility tours, the following were checked: manning, ac-cess control, adherence to procedures and LCO's, instrumentation, recor-der traces, protective systems, control rod positions, control room an-nunciators, radiation monitors, emergency power source operability, con-trol room logs, shift supervisor logs, and operating orders.
b.
System Alignment Inspection
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Operating confirmation was made of portions of the High Pressure Safety Injection and Primary Component Cooling System, including the surge tank, pumps, heat exchangers, Emergency Diesel cooling, and control room air conditioner.
Accessible valve positions and status were examined.
Power supply and breaker alignment was checked.
Visual inspection of major components was performed.
Operability of instruments essential to system performance was assessed.
The following deficiencies were identified in the Primary Component Cooling System:
1.
The filter inlet and outlet pressure gage isolation valve label tags were switched.
2.
The filter inlet and outlet valve label tags were switched.
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3.
There were no loop seals for pump gland leakoff as shown on the system print.
4.
The pressure switch which automatically starts the standby pump on low discharge pressure and a local pressure indicator were connected at locations opposite of that shown on the system print.
Items 1 and 2 were promptly corrected by changing the label tags.
A Design Change Request was initiated to correct the print discrepancies identified in item 4.
Actions to correct item 3 will will be followed up in a future inspection.
c.
Biweekly Inspections During plant tours, the inspector observed shift turnovers, chemistry sample results and the use of radiation work permits and Health Physics procedures.
Area radiation and air monitor use and operational status was reviewed.
Plant housekeeping and cleanliness were evaluated.
No concerns were identified.
d.
Plant Maintenance The inspector observed and reviewed maintenance and problem investigation activities to verify compliance with regulations, administrative and maintenance procedures, codes and standards, proper QA/QC involvement, safety tag use, equipment alignment, jumper use, personnel qualifications, radiological controls for worker protection, fire protection, retest requirements, and reportability per Technical Specifications.
Included in this review were reactor trip breaker maintenance and response time testing, repair of "D" traveling water screen, replacement of #2 main feedwater regulating valve primary controller.
e.
Surveillance Testing The inspector observed parts of tests, including the following, to assess performance in accordance with approved procedures and LC0's, test re-sults, removal and restoration of equipment, and deficiency review and resolution.
DG 2 Surveillance
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Control Room Ventilation Filter Flow Verification
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Operational check of Raw Water Pressure Switches and Solenoid Valves
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Magnetic Particle Test of Reactor Vessel Spare Studs
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Operational Test of BD-T-32 (post maintenance)
No concerns were identified.
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5.
Observations of Physical Security Checks were made to determine whether security conditions met regulatory re-quirements, the physical security plan, and approved procedures.
Those checks included security staffing, protected and vital area barriers, vehicle searches and personnel identification, access control, badging, and compensatory meas-ures when required.
Attachment A discusses details of this area.
6.
Radiological Controls Radiological controls were observed on a routine basis during the reporting period.
Standard industry radiological work practices, conformance to radio-logical control procedures and 10 CFR Part 20 requirements were observed.
Independent surveys of radiological boundaries and random surveys of non-radiological points throughout the facility were taken by the inspector. On September 24, 1986, a Health Physics Technician received a substantial radi-ation dose to his hands while transferring source material from a vial to a planchet.
The inspector reviewed the circumstances surrounding this event.
The licensee had received a technetium-99M source from a vendor for use in a proportional counter. A test was to be conducted to determine the sensi-tivity of the proportional counter to small beta emissions from a source with a comparatively large gamma flux.
The source arrived in a properly packaged container but needed to be evaporated prior to use.
A Health Physics Tech-nician utilized a syringe to transfer the liquid source from the vial to several planchets.
These planchets would then be used to test the propor-tional counter after varying degrees of radioactive decay.
Because of the dimensions of the vial and its location within the transportation container, the technician was required to momentarily remove the vial from its holder and conduct the necessary transfer of the source material.
After conducting the transfer, the technician checked his pocket dosimeter which showed an increase of 250 mrem.
The licensee subsequently recreated the actions of the technician to carefully measure times, distances and source strength of the incident.
Based on these values the licensee concluded that the technician received 1.9 rem to the left hand (worst case).
The quarterly limit for extremity dose rates is 18.75 rem.
The licensee had an independent review of the calculations performed onsite and two other organizations review the calculations offsite.
These reviews determined the calculated dose to be 2.70 rem.
The difference was attributed to the geometry of the vial with respect to the detector.
The licensee conducted an in-depth review of the occurrence.
As a result, changes were made to source handling procedures, receipt handling procedures and visitor access policy.
The inspector attended the Plant Operations Review Committee meeting on September 29, 1986.
During this meeting, the incident and corrective actions were discussed.
The inspector had no further questions.
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7.
In-Core Flux Mapping System (TI 2500/16) Inspection This inspection was performed to determine if a potential seismic interaction exists between the moveable In-Core Flux Mapping System and seal table at Westinghouse designed facilities or facilities with a similar design.
IE Information Notice No. 85-45, " Potential Seismic Interaction Involving The Moveable In-Core Flux Mapping System Used in Westinghouse Designed Plants" was issued June 6, 1985.
This notice provided notification of a potentially generic problem involving seismic interaction between the guide tubes at the seal table and portions of the flux mapping equipment located above the seal table.
Failures of flux mapping system tubing would constitute an unanalyzed small break LOCA because the flow would be from the bottom of the reactor vessel.
Maine Yankee is a Combustion Engineering plant with an incore flux mapping system similar to the Westinghouse design.
To address the concern of IE In-formation Notice No. 85-45, Maine Yankee requested that the Maine Yankee Pro-ject / Mechanical Analysis Group at Yankee Atomic review the structures and components which could impact the seal table in a seismic event.
The follow-ing list of components was identified :
1.
Flux Mapping System port selector mounted on top of the seal table steel frame.
2.
Spotlights on the pressurized cubicle wall.
3.
Unused ICI guide stand (steel frame bolted to the pressurizer cubicle wall).
4.
Steel ladders located at both ends of the seal table.
5.
Steel frame supporting the top of the ladders which is attached to the pressurizer cubicle wall.
6.
Flux Mapping System drive mechanisms (motor housing) mounted on top of the pressurizer cubicle.
7.
Guard rails on top of the pressurizer cubicle.
8.
Miscellaneous conduit and cable trays attached to the pressurizer cubicle wall.
9.
Miscellaneous loose items on top of pressurizer cubicle and adjacent to seal table (conduit covers, insulation, tools, etc.).
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Items 1 through 7 were analyzed and found to be adequately anchored for a seismic excitation of 0.lg.
Item 8 was judged to be adequately anchored based on actual earthquake experience data.
Item 9 was believed to be due to on-going outage activities and was corrected as part of the normal end-of-outage cleanup.
The licensee's actions were consistent with Westinghouse recommendations and no concerns were identified.
8.
Breaker Inspection Based on recent failures of General Electric (G.E.) AK-F-2-25 breakers at other facilities, the inspector reviewed the maintenance of this type of breaker.
Four failures of these breakers at other sites within the past three years have been attributed to mechanical binding of the trip shaft.
The pur-pose of this inspection was to identify important-to-safety functions provided by these breakers and review the maintenance conducted on these breakers.
General Electric AK-2-25 breakers are used in a variety of applications at Maine Yankee including feeder breakers to motor control centers, isolation breakers for some safety related motors and reactor trip breakers.
Reactor trip breakers were subject to numerous inspections in 1983-84.
As a result of the licensee's expanded program of routine maintenance and testing, these breakers have demonstrated reliable performance.
Additionally, the reactor trip breakers are designed with an undervoltage device trip function.
All other G.E. AK-2-25 breakers rely on shunt trip devices.
The reactor trip breakers were excluded from this inspection.
Buses 7 and 8 are 480 volt buses that utilize AK-2-25 breakers in safety-related applications.
These breakers provide power to service water pumps, motor control centers for emergency core cooling valves, reactor system motor operated valves, pressurizer heaters, fire pump P-4, and containment recircu-lation fans.
Due to the classification of these buses as safety related, the licensee utilizes procedure number 5-77-3, Inspection and Repair of GE AK-2-25 Circuit Breakers, each outage to conduct maintenance on these breakers.
All other AK-2-25 breakers are subject to a " clean, inspect and lubricate as necessary" maintenance.
Each outage, one third of the non-safety related breakers are subject to this maintenance.
These breakers are utilized as feeder breakers to other motor control centers, ventilation fans, some pres-surizer heaters and other local distribution feeder breakers.
These breakers are usually manually positioned and remain in that position.
Trip functions would only involve overcurrent.
On a loss of offsite power, these breakers would remain closed and would repower their respective loads when that bus was reenergized.
The inspector discussed the maintenance provided to these breakers with the maintenance department.
Although the maintenance has been effective in pre-venting failures of AK-2-25 breakers at Maine Yankee, it may not address the root cause of other breaker failures at other sites.
Specifically, other
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sites have experienced failures due to mechanical binding of the breakers, j
probably as a result of hardened grease on the trip shaft bearings.
The i
licensee is reviewing their preventative maintenance for AK-2-25 breakers to ensure it conforms to the manufacturers recommendation for breakers under
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these service conditions.
The inspector had no further questions.
9.
Manual Plant Trip
At 12:35 a.m. on October 19, 1986 an auxiliary operator noted the structural i
steel support for the isophase buswork at the main transformer was glowing red. This abnormal situation threatened the integrity of the main transformer.
The plant began decreasing power at 10 percent per hour.
After discussions were held on the problem, a manual plant trip was initiated at 1:11 a.m.
Subsequent inspection revealed that three of the four isophase buswork expan-sion plates were installed incorrectly.
The additional resistance of the
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j expansion joint caused induced currents in the protective tube to flow through the structural steel +.c ground.
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The plant is designed with three isophase buses that run from the main genera-tor to the main transformer.
Each of these buses has a protective tube sur-
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rounding it.
Expansion joints are located on the tube to allow movement of j
the tube.
During the 1984 Refueling Outage (completed in June 1984), the i
plant installed a new style grounding device for the isophase tube expansion
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points.
These new grounding devices consisted of a flat plate and flexible t
metal strips.
Four of these devices were installed in each expansion joint.
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During troubleshooting of the problem, the licensee determined that three of
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the grounding devices were installed without conductive grease (which is used
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to prevent an oxidation layer buildup).
This expansion joint as well as the
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nearby structural steel showed signs of heating.
The licensee manufactured new expansion joint grounding straps and returned the isophase buses to ser-vice.
The plant returned to power operations at 9:29 on October 19, 1986.
Heat sensitive photographs of the expansion joints were taken when the plant
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returned to 100 percent power. The resident inspectors will follow any further corrective actions by the licensee.
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10.
Inverter Failure i
On October 7, 1986, the #1 inverter failed, deenergizing vital bus 1 at 4:05 a. m.
Along with the instrumentation lost as a result of vital bus 1 deener-gizing, the plant entered two remedial action statements of the Technical Specification due to the loss of the Saturation Monitors and the Auto Closure
System for the Auxiliary Feedwater Regulating Valves.
After ensuring an electrical fault did not exist on vital bus 1, it was crossconnected to vital bus 4.
Remedial Action Statements of Technical Specifications 3.9.3 and 3.22.3 were exited at 5:25 a.m.
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Operations personnel thoroughly reviewed possible problems in operating with
vital buses 1 and 4 cross-connected and in returning the inverter to service.
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Precautions were taken by the operators to prevent electrical spikes to the RPS channels while shifting power supplies for #1 vital bus. The operators
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discussed the actions required if spikes did occur and were well prepared.
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Corrective maintenance was performed on inverter #1 and at 1:38 p.m. vital bus 1 was returned to its normal supply via inverter 1.
Maine Yankee is designed with 4 vital buses, each supplied through its own inverter from a battery bus.
Vital buses 1 and 4 can be crossconnected and vital buses 2 and 3 can be crossconnected.
On April 17, 1986, inverter #3 failed. On August 10, 1986, #1 inverter failed causing a plant trip (another failure of a feedwater regulating valve auto relay caused a low level in #1 steam generator).
The inspector discussed these three inverter failures with the licensee.
The licensee plans to rebuild all inverters during the upcoming outage scheduled to begin in March 1987.
Additional reviews are underway to enhance the reliability of the inverters.
The inspector had no further questions.
11.
Yankee Atomic Electric Company Yankee Atomic Electric Company (YAEC) provides a number of support functions to Maine Yankee.
An inspection at YAEC in Framingham, Mass. was conducted in order to familiarize the inspector with those services.
YAEC provides services to Maine Yankee including Engineering, Quality Assur-ance and Projects Support.
Meetings were held with a variety of managers to familiarize the inspector with the areas of expertise of each department, current projects of interest and areas where future work is planned.
The inspector conducted a tour of the laboratory and computer areas.
The inspection was informative and provided the inspector with the necessary contacts for future reference.
12.
Exit Interview Meetings were periodically held with senior facility management to discuss the inspection scope and findings.
A summary of findings for the report period was also discussed at the conclusion of the inspectio M
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ATTACHMENT A MAINE YANKEE SECURITY OBSERVATIONS THIS PAGE CONTAINS SAFEGUARDS INFORMATION AND IS NOT FOR PUBLIC DISCLOSURE.
IT IS INTENTIONALLY LEFT BLANK.
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