ML20059C252
| ML20059C252 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 10/25/1993 |
| From: | Feigenbaum T NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NYN-930145, NUDOCS 9311010067 | |
| Download: ML20059C252 (8) | |
Text
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g, M4 NOdh P.O. Box 300 Seabrook, NH 03874 Telephone (603)474 9521
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[C Facsimile (603)474 2987 Energy Service _ Corporation Ted c. Feigenbaum Senior Vice President and Chief NuclearOfficer NYN-930145 October 25,1993 United States Nuclear Regulatory Commission Washington, D.C. 20555 Attention:
Document Control Desk
References:
(a)
Facility Operating License No. NPF-86, Docket No. 50-143 (b)
USNRC Letter dated August 16,1993, " Inspection Report No. 50-443/93-80,"'
M. W. Ilodges to T. C. Feigenbaum
Subject:
Response to (Inresolved Items From EDSFI Gentlemen:
In accordance with the request contained in Reference (b), the North Atlantic Energy Service Corporation (North Atlantic) response to the unresolved items identified during the April 26 to May 21, 1993 Electrical Distribution System Functional Inspection (EDSFI) is provided as Enclosure 1.
Should you have any questions concerning this response, please contact Mr. James M. Peschel, Regulatory Compliance Manager, at (603) 474-9521, extension 3772.
Very truly yours, N
Ted C. Feigenba{um -
TCF:JES/jes j
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Enclosure
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,UnitedStates Nuclear Regulatory Commission October 25,1993.
Attention:
Document Control Desk
- Page two
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cc:
Mr. Thomas T. Martin Regional Administrator
.l U.S. Nuclear Regulatory Commission Region 1 475 Allendale Road King of Prussia, PA 19406 Mr. Albert W. De Agazio, Sr. Project Manager Project Directorate I-4 Division of Reactor Projects U.S. Nuclear Regulatory Commission Washington, DC 20555 Mr. Noel Dudley NRC Senior Resident inspector P.O. Box 1149 Seabrook, NH 03874 t
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Nonh Atlantic October 25,1993 i
i ENCLOSURE 1 TO NYN-93145 1
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RESPONSE TO UNRESOINED ITEMS FROM THE EDSFI i
in a letter dated Augus' 16,1993 [ Reference (b)], the NRC identified eight unresolved items identiGed during the April 26 to May 21,1993 Electrical Distribution System Functional Inspection (EDSFI). In accordance with tF instructions provided in the cover letter to the inspection report, the North Atlantic Energy Service Corporation (North Atlantic) response to the unresolved items is provided below.
UNRI 93-80-01: The team found that the licensee was not performing any periodic testing of the bus fast transfer scheme dead time. Additionally, Procedure MX0508.01, which tests the breaker opening and closing time, does not include the testing of the early "b" contacts that initiate the transfer. The team was concerned that the early "b" contact may fall out of calibration with time, which may prevent the timely initiation of the bus transfer. To address this, the licensee committed to develop a periodic testing criteria for the bus transfer scheme. This issue is umesolved per ding the licensee's establishing adequate test criteria for the bus fast transfer scheme.
Response: North Atlantic is currently developing test criteria to periodically test the response time of the bus fast transfer scheme. This test criteria will be added to Operations Procedure OX1446.02, " Bus E5 and E618 Month Offsite Power Supply Transfer Operability," and will include monitoring a fast transfer to verify that the transfer time is within acceptable limits. It is anticipated that this procedure will be developed by February 28,1994. North Atlantic will test the fast transfer scheme response time during the third refueling outage which is scheduled to be completed by May 20,1994.
North Atlantic will also revise Maintenance Procedure MX0508.01, "4.16 kV Breaker Inspection, Testing and PM," to incorporate testing of the early "b" contacts. This testing will provide assurance that the early "b" contact will perform its required function in the transfer scheme. It is anticipated that this procedure revision and the testing will be completed during the third refueling outage which is scheduled to be completed by May 20,1994.
UNRI 93-80-02: With regard to associated circuits, the team stated that the licensee's use of the following requires further justiGcation: (1) non-environmentally-qualified circuit breakers inside containment; (2) commercial grade components in associated circuits without appropriate qualification or dedication; and (3) circuit breakers for which qualification was not demonstrated by periodic testing in accordance with the SER.
Response: North Atlantic's overall action plan on associated circuits, in addition to the specific issues stated in the unresolved item, are discussed below.
Overall Action Plan on Associated Circuits: North Atlantic has issued Engineering Evaluation 93-34,
" Associated Circuit Protective Devices," to identify the installed protective devices that have special requirements related to associated circuits. North Atlantic will revise the UFSAR to specifically address and clarify the requirements for design, procurement, and testing of associated circuit protective devices.
It is anticipated that this revision will be prepared by December 15, 1993.
North Atlantic is also currently developing a corporate procedure to delineate programmatic requirtments and responsibilities related to associated circuits. This procedure will include all associated circuit programmatic and procedural commitments identified in the revised UFSAR. It is anticipated that this procedure will be developed by December 31,1993.
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'l Training will also be conducted for the appropriate North Atlantic personnel on the associated circuits procedure. It is anticipated that this training will be completed by March 30,1994.
To facilitate implementation of the associated circuits procedure and to provide additional clarity, North -
Atlantic has compiled a list of protective devices with associate circuit requirements (Engineering Evaluation 93-34) and will identify these devices on the appropriate plant drawings by December 31, i
1993.
Non-Environmentallv-Oualified Circuit Breakers Inside Containment:
North Atlantic initiated an operability determination for power panels 1-PP-8A and ' ?P-8B that were located inside the containment building. This evaluation concluded that the circuit breakers in these power panels would function in the expected harsh environment. This conclusion was based on an analysis of critical breaker materials and on the understanding that thermal-magnetic breakers show a decrease in current carrying capability with an increase in temperature.
North Atlantic also verified the qualification of these breakers by testing samples taken both from the power panels in the containment and inventory. The testing was conducted at NTS/Acton Laboratories and included functional testing at 80% of rated current and trip testing at a fault current of 300% of rated current. The breakers functioned properly after thermal and radiation aging, during elevated temperature and steam break trip testing, and during MSLB/LOCA testing.
North Atlantic is in the process of developing a design change to address long term resolution of the breakers located inside the containment. This design change, which is scheduled to be developed by December 15, 1993, will remove the cables for power panels 1-PP-8A and 1-PP-8B from the existing cable trays and reroute them in conduit. These breakers will therefore no longer be considered protective devices with associated circuit requirements. This design change will be installed during the third refueling outage which is scheduled to be completed by May 20,1994.
Commercial Grade Components in Associated Circuits Without Aporopriate Oualification or Dedication:
The inspection report noted that North Atlantic identified several non safety-related circuit protective devices that had been purchased as commercial grade components and therefore were not similar to Class lE devices with regard to qualification or dedication. North Atlantic performed an evaluation that showed 37 commercial breakers were installed in the plant and 13 of these acted as protective devices for cable carrying non-Class IE loads that actually shared raceways with cable carrying Class IE loads.
North Atlantic will either test these 37 circuit breakers or replace them with breakers that have been previously tested, unless they were determined to be exempt in Engineering Evahmtion 93-34.' The testing will include verification of instantaneous and thermal tripping ability in accordance with the i
manufacturer's published data. It is anticipated that the aforementioned testing or replacement will be completed before the end of the third refueling mtage which is scheduled to be completed by May 20, 1994.
With regard to fuses that were procured as non-safety related, North Atlantic will evaluate and test, when required, all installed fuses (unless they were determined to be exempt in Engineering Evaluation 93-34) that may be acting as protective devices with associated circuit requirements. It is anticipated that the.
aforementioned evaluation and testing will be completed by November 15, 1993.
T North Atlantic will revise the North Atlantic Procurement Manual (NAPM) to ensure that future procurement of protective devices with associated circuit requirements includes sufficient controls so that the protective device can perform its current interrupting function. It is anticipated that the NAPM revision will be completed by December 15, 1993.
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, Additionally, North Atlantic will revise the Seabrook Station Maintenance Manual (SSM A) to add specific controls to Work Requests and Repetitive Task Sheets involving replacement items acting as associated circuit protective devices. This revision, which is scheduled to be completed by December 31,1993, will ensure consistent application of controls for associated circuits.
Circuit Breakers for Which Oualification Was Not Demonstrated by Periodic Testine in Accordance With thg_SER: North Atlantic has identified a number of associated circuit protective devices that were not tested in accordance with the requirements in both the UFSAR and SER. North Atlantic is currently evaluating the testing requirements and developing a testing program for both Class IE protective devices and protective devices with associated circuit requirements considering both vendor recommendations and regulatory requirements. It is anticipated that this program will be developed by December 31,1993.
UNRI 93-80-03: At the time of the inspection, the team determined that, although the trip characteristics of circuit breakers specified in the Technical Specifications were periodically tested, those of other breakers were not. Also, it was not clear what commitments had been made by the licensee regarding trip testing of the non-safety-related circuit breakers. The licensee agreed that they would evaluate testing requirements for all breakers ano develop a testing program which would consider vendor recommendations as well as regulatory requirements. SNtion 5.2.4 also noted that not all Class IE and.
Non-Class IE molded case circuit breakers are tested on a regular basis.
Response: North Atlantic is currently evaluating the testing requirements and developing a testing program for Class IE protective devices and protective devices with associated circuit requirements considering both vendor recommendations and regulatory requirements. Additional details regarding this issue are described in response to Unresolved item 93-80-02, above. It is anticipated that this testing program will be developed by December 31,1993.
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. UNRI 93-80-04: The Elgar inverters are equipped with a de undervoltage shutdown feature that is currently set at approximately 105 volts sensed at the de link within the inverters. This may not be l
adequate for the operation of the inverters with the existing acceptance criteria of 105 volts at the battery.
Furthermore, the licensee had identified that a setpoint was neither specified nor periodically tested.. The licensee has committed to specify a setpoint by September 30, 1993. Additionally, the licensee has j
committed to develop a procedure to verify de shutdown features and continuous output regulation for the full range of de input by October 30, 1993, and conduct maintenance department training on the procedure by December 30,1993.
Besnonse: North Atlantic is currently developing a Minor Modification (MMOD) to change the setpoint for the Elgar inverter de undervoltage trip setpoint. North Atlantic will also develop a procedure for implementing the aforementioned Elgar setpoint change and to verify de shutdown features and continuous output regulation for the full range of the de input. It is anticipated that the MMOD and the procedure will be developed by January 15, 1994. Additionally, the setpoint change will be implemented during the third refueling outage which is anticipated to be completed by May 20,1994.
j North Atlantic will also conduct training on the aforementioned procedure. It is anticipated that this training will be conducted by February 2.8,1994.
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,UNRf 93-80-05: Calculation 9763-3-ED66F, which determined the minimum voltages at the loads for the DC system, needs to be revised to show the minimum voltages at the loads assuming 105 Vdc at the battery instead of at the distribution panels.
R_fsfonse: Calculation 9763-3-ED66F, which determined the minimum voltages at the loads for the DC system, will be revised to show the minimum voltages at the loads assuming 105 Vdc at the battery. This revision will demonstrate that sufficient voltage will be available at the load terminals. It is anticipated that this calculation will be revised by February 28,1994.
UNRI 93-80-06: The minimum Emergency Diesel Generator (EDG) fuel oil quantity for seven-day operation assuming diesel fuel leakage and normal performance degradation needs to be established.
Additionally, an on-going program needs to be implemented to control and monitor future load changes and performance changes. It was also noted that no controlled tests were performed to determine the actual fuel consumption rates of the EDGs at various loads to support the fuel consumption rate used in the calculations.
Response: The EDG fuel oil consumption calculation C-S-1-E-0161 has been revised and the existing 60,000 gallon minimum fuel oil limit was verified to be adequate. While this calculation did not explicitly consider leakage, it did consider the specific loads on the EDGs and the 10% margin recommended by Regulatory Guide 1.137. Based on the results of calculation C-S-1-E-0161, Revision 3, the most demanding diesel required 56,903 gallons of fuel oil. Accounting for the 162 gallon unusable volume at the tank's nozzle projection, a total tank volume of 57,065 gallons is required for seven-day operation.
North Atlantic has revised procedures EX1804.059, " Emergency Diesel Generator 1 A 24 Hour Load Test and Hot Restart Surveillance," and EX1804.060, " Emergency Diesel Generator IB 24 Hour Load Test and Hot Restart Surveillance," to monitor EDG fuel consumption during the 18 month surveillance in order to substantiate the fuel oil consumption rates used in the calculation. These surveillances are scheduled to be performed during the third refueling outage which is expected to be completed by May 20,1994. Additionally, in order to monitor future EDG performance, North Atlantic will continue to perform these surveillances every 18 months.
With regard to controlling and monitoring future load changes, the existing North Atlantic design control process ensures that all proposed design changes are evaluated to determine their impact on EDG loading and fuel oil consumption. Specifically, Engineering Department Procedure 30040, " Design Change Processing," ensures that the Electrical Engineering Department reviews all design changes against a checklist entitled "Interdiscipline Review Electrical Engineering Evaluation." This checklist contains an item to ensure that proposed design changes consider bus loading including diesel generators and the associated fuel oil calculation, batteries, transformers and inverters.
1 UNRI 93-80-08: The EDG air start subsystem utilizes threaded union couplings to connect the various piping and components on the air start skid. These piping joints see running vibration loads and seismic i
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Additionally, the threaded couplings did not have any torque requirements. This issue is unresolved pending a detailed evaluation of the acceptability of the threaded couplings used in vibration and shock. areas, incorporating torque requirements for threaded fittings in licensee's applicable procedures.
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, Response: As described above, the concern is that seismic and vibratory induced Dexure across the union joints installed in the EDG air start skid piping could result in rotation of the union hubs resulting in leakage of the joint. The subject pipe unions were supplied by Colt as part of the original EDG air start skid assembly piping. They are carbon steel forgings with a 3000 psi pressure rating and are attached to skid piping by socket welding. The union sizes include 1/4",3/4", and 2". They are manufactured as three piece assemblies consisting of two mating male / female hubs joined together by means of a threaded coupling. The outer diameter of the female hub is threaded to accept the coupling. Tightening drives the male and female hub ends together creating a seal. The machined contact face is metal to metal seat with no internal gasket.
When welded into a pipe line the union forms a very rigid assembly. Tightening produces shear stresses in the threads of the coupling that are directly reacted through compression of the union seating surfaces creating a clamping force great enough to effect a pressure seal. In this configuration, the coupling nut acts as a rigid link preventing flexure or rotation between the two hubs. Piping loads would have to be high enough to cause shear tear out of the coupling threads for the seal to fail.
Seismic vibration or shock loosening of the unions will not occur. Vibratory forces must be of sufficient magnitude and also have a right angle component to cause thread slippage and subsequent loosening. The seismic demand on the system piping is low; the air start skids are located in the Diesel Generator Building rigidly attached to the elevation 21'-6" stab. Seismic ground response spectra applicable to the air start skid has a peak Safe Shutdown Earthquake (SSE) value of 0.25 g's.
The unions are concentrically constructed and consequently do not have a geometry that can be affected by transverse seismic loosening forces. A flexible connection between the air start skid piping and the compressor isolates potential vibrations caused during compressor operation.
Additionally, the original installation of these unions by Colt employed only standard work practices and techniques. Precise joint torque values for the unions were neither required nor specified as part of the original Colt air start skid seismic qualification.
Proper tightness requirements for the air start skid piping unions are ensured by the successful
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performance of a pressure test verifying leak tightness of the entire system. Control of the Seabrook Station post maintenance testing activities is part of the plant's Work Control Program and is performed in accordance with Station procedures.
Based on the foregoing, the forged steel unions installed in the EDG Air Start system will perform as intended under both normal operational loads and in a seismic shock and vibration environment. Specific torque requirements for these unions are not necessary. Snug tight is adequate to ensure proper performance and to maintain the original seismic qualification for the Air Start system unions for all postulated loading conditions.
UNRI 91-8. 0 09: Calculation 6.01.42.01, Revision 6, did not consider the case of loss of the train "B" emergency switchgear room HVAC supply fan following a reactor trip and a possible loss of offsite power.
ErSP_0me: Calculation 6.01.42.01, has been revised to document the actual heat loads experienced in the switchgear room. This revision considered the loss of the train "B" switchgear room ventilation supply fan following a reactor trip and a possible loss of offsite power. Under these conditions, room
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temperatures are maintained below design base limits.
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