IR 05000309/1987024
| ML20236H494 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 10/28/1987 |
| From: | Lester Tripp NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20236H482 | List: |
| References | |
| 50-309-87-24, IEB-86-003, IEB-86-3, IEB-87-001, IEB-87-1, NUDOCS 8711040165 | |
| Download: ML20236H494 (6) | |
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U.S. NUCLEAR REGULATORY COMMISSION
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REGION I
l Docket / Report:
50-309/87-24 License:
OPR-36 Licensee:
Maine Yankee Atomic Power Inspection At:
Wiscasset, Maine Dates:
September 2 to October 5, 1987 Inspectors:
Cornelius F. Holden, Senior Resident Inspector R hard J. Freudenberger, Resident Inspector 4pproved By:
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H_owell E. Tripp, Chief, Reactor Projects Date'
Section 3A, Projects Branch No. 3 Summary:
Inspection on September 2 to October 5, 1987 (Report No.
50-309/87-24 Areas Inspected:
Routine resident inspection (189 hours0.00219 days <br />0.0525 hours <br />3.125e-4 weeks <br />7.19145e-5 months <br />) of the control room, accessible parts of plant structures, plant operations, radiation protection, l
physical security, plant operating records, maintenance and surveillance.
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Results:
No violations were identified.
Major improvements in plant house-keeping were observed.
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8711040165 071101 PDR ADOCK 05000309
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i DETAILS
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1.
. Persons Contacted Within this report period, interviews and discussions were conducted with various licensee personnel, including plant operators, maintenance tech-t nicians and the licensee's management staff.
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2.
Summary of: Facility Activities At the beginning' of the report period the plant was operating at 100 per-cent power.
On September 23, power was reduced to 75 percent for routine turbine valve surveillance testing and mussel control operations.
The plant was returned to full power on September 24 and remained there for j
the rest of the report period.
3.
Followup on Previous Inspection Findings a.
(Closed) Bulletin (50-309/86-8U-03). Potential Failure of Multiple
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ECCS Pumps Due to Single Failure of Air-0perated Valve in Minimum Flos Recirculation Line.
This IE Bulletin requested that licensees
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review the design of their Emergency Core Cooling System (ECCS) pumps recirculation systems which may. cause failure of multiple ECCS pumps.
In response to this bulletin, Maine Yankee stated in a letter dated December 2, 1986, that the recirculation lines for the ECCS pumps contain motor-operated isolation valves that.are normally open and would fail "as is" on loss of power. Maine Yankee concluded that the ECCS pump recirculation lines are not vulnerable to a single active failure which would result in the failure of all Emergency Core Cool-ing System pumps.
The inspector verified the information in tho letter and had no further questions.
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b.
(Closed) Bulletin (87-8U-01) Thinning of Pipe Walls in Nuclear Power j
Plants. All licensees were requested to provide information concern-
ing their programs f.or monitoring the wall thickness of pipes in j
condensate, feedwater, steam and connected high-energy piping sys-tems. Maine Yankee's response dated September 11, 1987, provided a j
detailed report on the status of their program for monitoring wall thickness in high energy piping systems.
The monitoring program at Maine Yankee involves routine ultrasonic inspection of feedwater and other two phase flow systems at susceptible locations during refuel-
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ing outages.
The inspector reviewed the information and found it to be complete and accurata.
The inspector had no further questions.
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4.
Routine Periodic Inspections'
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a.
Daily Inspection
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During routine facility tours, the following were checked: manning, I
access control, adherence to procedures and LCO's, instrumentation,-
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l recorder traces, protective systems, control rod positions,'contain-
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ment pressure, control room annunciators, radiation monitors, emerg-I
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ency power ' source. operability, control room logs, shift supervisor
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logs, and operating orders.
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b.
System Alignment Inspection
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Operating _ confirmation was made of the ventilation systems for the control room, the primary auxiliary building, the fuel building, and the safeguards building.
Accessible valve and damper positions and status were examined.
Power supply. and breaker alignment was checked. Visual inspection of major components was performed.
Oper-ability of instruments essential to system performance was assessed.
No deficiencies were identified.
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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 opera-
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tional status were reviewed.
d.
Plant Maintenance The inspector observed the replacement of the letdown prefilter ( FL-35B), the adjustment of a primary water flow control valve
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(PW-F-59), and the replacement of the linear amplifier card in the channel 0 power range nuclear instrumentation. This review of prob-lem investigation and maintenance activities was performed to verify
adherence to administrative and maintenance procedures, incorporation of codes and standards into work packages, proper QA/QC involvement, safety tag use, equipment alignment, personnel qualifications, radio-logical controls for worker protection, test requirements, and repor-tability per Technical Specifications.
The inspector identified no discrepancies within the scope of this review, e.
Surveillance Testing The inspector observed parts of tests to assess performance in accordance with approved procedures and LCO's, test results, removal
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from service and restoration of equipment, and deficiency review and resolution.
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On September 17, 1987, during a monthly surveillance test of the steam driven auxiliary feedwater pump, the safety valve on the steam supply to the pump lifted, vibrated the steam line, which caused the turbine trip mechanism to operate, tripping the turbine. A similar occurrence was reviewed in Inspection Report 50-309/87-17 (section
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8) in which the safety valve operated and tripped the turbine when l
the pressure in the steam supply line was high during pump starts.
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As part of the corrective actions for-the previous problem, the sur-j veillance procedure was modified so that the aux 111ary feedwater puinp
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was aligned to supply water to the steam generators during the test,
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instead of operating the pump on recirculation flow. As a result of this change when the test was run' with the plant at full power a feedwater transient was initiated which required the control room i
operator to rapidly throttle the emergency feedwater regulating
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valves.
When the valves were throttled the auxiliary feed pump's load decreased rapidly causing a pressure increase in the steam
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supply line to the pump's turbine.
This pressure increase was suf-
ficient to cause the safety valve to operate (within its expected range).
The operation of the safety valve caused the turbine to j
trip. The licensee declared the auxiliary feedwater pump inoperable j
and conducted a review of the test procedure to determine whether the i
objectives of the monthly surveillance could be met with a test that i
had less impact on overall plant operations. The test was modified
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to provide for an operability run of the pump on recirculation flow with the pressure reducing valve controlled manually, then a remote start test feeding the steam generators for a short time.
Since, under accident conditions the emergency feedwater regulating valves would not need to be throttled quickly, this test method is con-sidered satisf actory. The retest was conducted on September 18 and was completed satisfactorily.
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The licensee has determined that the root cause of these trips is the inability of the pressure reducing valve to respond as quickly as the i
governor valve.
Therefore, when the governor valve closes on a decrease in the load on the pump, the pressure in the supply line increases to the setpoint of the safety valve before the pressure reducing valve can respond to correct the pressure. The operability of the pump is not in jeopardy since the pump will start and run under the same conditions it would be expected to run if required for accident mitigation.
The licensee has expedited the Engineering Design Change Request (EDCR) to relocate the safety valve to a position where its operation will not cause the steam supply line to vibrate, yet where it will provide the necessary protection for the turbine casing.
The inspector will foibw the installation of the
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EDCR.
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f.
Backshift Inspections The Inspectors conducted backshift inspections on September 4, 7,10, 23 and October 4.
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Plant Housekeeping Plant Housekeeping was evaluated during - this report period. Signif-icant improvements were observed in all areas of the plant, espec-
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ially in the Spray Building, Lower Primary Auxiliary Building and Containment. Two items for possibie improvement were identified dur-
ing the inspection including potential overheating of electric motors due to excessive lubrication of rotating machinery and missing cap fittings for drain connections, In response to the first concern the licensee conducted an independent audit of the the plant lubrication practices.
Recent failure of electric motors were reviewed and excessive lubrication was not found to be a contributor to these failures.
Improvements are planned based on the findings of the
audit. Additionally, the licensee is reviewing the drain cap issue and plans to take corrective actien.
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Observations of Physical Security Checks were made to determine whether security conditions met regulatory requirements, 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 measures when required.
The licensee continues to make improvements to the security system including upgrading of the protected area. fence, access control and detection system upgrades. No deficiencies were identified.
6.
Radiological Controls Radiological controls were observed on a routine basis during the report-ing period.
Standard industry radiological work practices, conformance to radiological control procedures and 10 CFR Part 20 requirements were observed.
Independent surveys of radiological boundaries and random sur-veys of nonradiological points throughout the facility were taken by the inspector.
The plant has instituted a variety of improvements in the Radiological Controls area including procedure revisions, dedicated tech-nician coverage for certain jobs, and policy changes including a change to clean step-off pads at radiation boundaries.
The overall affect of these changes has been an improvement in the radiological work practices at the J
site.
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7.
Bypass of Non-essential Diesel Generator Trios (RI TI 87-04)
The inspector reviewed the detailed logic for diesel generator protective trips to determine if the diesel generator was susceptible to non-essen-tial trips during loss of power conditions.
The diesel generator trip devices -installed at Maine Yankee consist of five electrical trips which open the generator output breaker and one mechanical overspeed trip that trips the fuel rack to the no fuel posi-tion. The five electrical trips are overspeed, no generator field, over-current,. generator phase di f feren tia'l and engine.stop delay auxiliary (normal engine shutdown). The power supply for the electrical trips comes from the safety class battery buses.
Because the diesel generator receives an auto-start signal on low bus voltage and none of the protec-tive devices are bypassed on an auto-start, the diesel generator auto start scheme is unaffected by non essential trips during loss of power conditions.
A review of the diesel generators maintenance histories revealed no adverse effect on reliability of the emergency power system j
due to the design of the protective devices installed on the diesel generators. The inspector had no further questions.
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Commitment Management System
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The inspector reviewed the licensee's Commitment Management System and the j
Operational Assessment System.
These two systems are part of the licer.-
i see's program for Information Management.
The Commitment Management System (CMS) is used to track requests for information from various regu-latory and industry sources. The system utilizes action request forms and bi-weekly status reports to track commitment progress and assure their l
timely completion.
The Operational Assessment System (OAS) screens and I
evaluates in-house and industry experience for significance to Maine I
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Yankee. When a relevant subject is identified, the system coordinates the review and resolution effort. When action is required to address issues raised during an OAS review, the system provides for followup and review I
of those actions.
The inspector reviewed each of the systems and con-i ducted a spot check of the records and data tracking systems.
No defic-l iencies were identified.
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Exit Interview Meetings were periodically held with senior facility management to discuss i
the inspection scope and findings.
A summary of findings for the report
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period was also discussed at the conclusion of the inspection.
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