ML071290579
| ML071290579 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie, Seabrook, Turkey Point, Duane Arnold  |
| Issue date: | 05/08/2007 |
| From: | Stall J Florida Power & Light Co |
| To: | Document Control Desk, NRC/NRR/ADRO |
| References | |
| GL-07-001, L-2007-067 | |
| Download: ML071290579 (15) | |
Text
0Florida Power & Light Company, 700 Universe Boulevard, P.O. Box 14000, Juno Beach, FL 33408-0420
- PL MAY 0 8 2007 U. S. Nuclea:" Regulatory Commission L-2007-067 Attn: Document Control Desk 10 CFR 50.54(f) 11555 RockNille Pike Rockville, ME) 20852 Re:
Florida Power and Light Company St. Ltcie Units 1 and 2 Dockot Nos. 50-335 and 50-389 Turkey Point Units 3 and 4 Dockot Nos. 50-250 and 50-251 FPL Energy Seabrook, LLC Seabrook Station Docko,.t No. 50-443 FPL E'nergy Duane Arnold, LLC Duan a Arnold Energy Center Dockot No. 50-331 Response to NRC Generic Letter 2007-01 Inaccessible or Underground Power Cable Failures that Disatble Accident Mitigation Systems or Cause Plant Transients On February 7, 2007, the Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2007-01, "Inaccessible or Underground Power Cable Failures that Disable Accident Mitigation Systems or Cause Plant Transients" (ADAMS Accession No. ML00703606650).
The GL discusses moisture-induced degradation or failure of safety-related cables that are routed through uncerground conduits, concrete duct banks, cable trenches, cable troughs, underground vaults, or are directly buried. The GL requests that certain information regarding cable failure., and cable inspection, testing and monitoring programs be submitted to the NRC within 90 days of the date of the GL.
Florida Power & Light Company (FPL), the licensee for the St. Lucie Nuclear Plant, Units 1 and 2, and the Turkey Point Nuclear Plant, Units 3 and 4, FPL Energy Seabrook, LLC (FPL Energy Seabrook), the licensee for Seabrook Station, and FPL Energy Duane Arnold, LLC, the licensee for Duane Ariold Energy Center, hereby submit the 90-day response requested by GL 2007-01. provides the FPL St. Lucie Nuclear Plant response. Attachment 2 provides the FPL Turkey Doint Nuclear Plant response. Attachment 3 provides the FPL Energy Seabrook Station resp nse. provides the FPL Energy Duane Arnold Energy Center response.
an FPL Group coripany
St. Lucie Units : and 2, Docket Nos. 50-335 and 50-389 Turkey Point Ut its 3 and 4, Docket Nos. 50-250 and 50-251 Seabrook Statio;, Docket No. 50-443 Duane Arnold Energy Center, Docket No. 50-331 L-2007-067, Page 2 of 2 The guidance provided in Enclosure 2 to NRC letter dated April 13, 2007 (ADAMS Accession No. ML0709-10311), to the Nuclear Energy Institute was used by FPL, FPL Energy Seabrook, and FPL Ene'gy Duane Arnold in preparing the response to the GL.
The attachec information is provided pursuant to the requirements of Section 182a of the Atomic Energy Act of 1954, as amended and 10 CFR 50.54(f).
There are no new commitments within this letter, or within the Attachments.
Please conta,;t Rajiv S. Kundalkar at (561) 694-4848 if you have any additional questions regarding the 3e responses.
I declare unde3r penalty of perjury that the foregoing is true and correct.
Executed on :he
,-4L, day of
_l*
2007 Sincerely yours,
'J J.A.a~ll Senior Vice F resident, Nuclear and Chief Nuclear Officer Attachments: (4) cc:
Regional Administrator, Region I Regioial Administrator, Region II Regionial Administrator, Region III USNFC Project Manager, St. Lucie and Turkey Point USNF.C Project Manager, Seabrook Station USNF.C Project Manager, Duane Arnold Energy Center Senio Resident Inspector, USNRC, St. Lucie Senio Resident Inspector, USNRC, Turkey Point Senio" Resident Inspector, USNRC, Seabrook Station Senio" Resident Inspector, USNRC, Duane Arnold Energy Center
ATTACHMENT 1 ST. LUCIE NUCLEAR PLANT UNITS 1 AND 2 RESPONSE TO GENERIC LETTER 2007-01
St. Lucie Units : and 2, Docket Nos. 50-335 and 50-389 Turkey Point Ui.its 3 and 4, Docket Nos. 50-250 and 50-251 Seabrook Station, Docket No. 50-443 Duane Arnold Energy Center, Docket No. 50-331 L-2007-067, Attachment 1, Page I of 3 ST. LUCIE NUCLEAR PLANT UNITS 1 AND 2 RESPONSE TO GENERIC LETTER 2007-01 INACCESSIBLE OR UNDERGROUND POWER CABLE FAILURES THAT DISABLE ACCIDENT MITIGATION SYSTEMS OR CAUSE PLANT TRANSIENTS NRC Request 1: Provide a history of inaccessible or underground power cable failures for all cables that are within the scope of 10 CFR 50.65 (the Maintenance Rule) and for all voltage levels. Indicete the type manufacturer, date of failure, type of service, voltage class, years of service, and the root cause for the failure.
FPL Response:
At St. Lucie, there have been no in-scope 10 CFR 50.65 inaccessible or underground power cable failures. This determination was rendered through reviews of condition reporting databases, the work control database, and the Cable and Raceway Schedule. However, there was one Unit 1 AC power cable that testing, performed during the spring 2007 refueling outage, identified as degraded.
The degraded cable, 480 volt power cable 10309A-SB, is a Unit 1 containment penetration feed-through cable. The cable was identified with a low megger reading on the C-Phase conductor located between the containment annulus and the outer containment concrete wall. The cable will be replaced, during the current outage, to prevent potential future failure. The cause of the cable's low megger raading is under investigation. See Attachment 1, Table 1, for the requested cable information.
NRC Request 2: Describe inspection, testing and monitoring programs to detect the degradation of inaccessible or underground power cables that support emergency diesel generators (E DGs), offsite power, essential service water (ESW), service water, component cooling water and other systems that are within the scope of 10 CFR 50.65 (the Maintenance Rule).
FPL Respons e:
St. Lucie has a manhole inspection program for safety related manholes to ensure that they are clean, dry, that the sump pump is working (if applicable) and to repair any degradation to the cables or manhole. The objective of this program is to provide assurance that the systems designed to minimize the amount of time the cable is exposed to a wet environment are operational. *rhe current inspection cycle is every 2 years and the program is a License Renewal corr mitment for both Units at the site. The program is controlled under the Preventative Maintenance Program Activity 99-Manhole Inspect. Manholes are sealed to prevent most moisture intrusion, and drain to manholes with sumps.
St. Lucie does not have a formal program for testing and monitoring for degradation of inaccessible or underground power cables. However, periodic cable testing is done as part of the normal plant maintenance program. Cables are tested as part of the normal preventative maintenance program for motors from the smallest Limitorque motor operated valve to the
St. Lucie Units ] and 2, Docket Nos. 50-335 and 50-389 Turkey Point Ur its 3 and 4, Docket Nos. 50-250 and 50-251 Seabrook Station, Docket No. 50-443 Duane Arnold Energy Center, Docket No. 50-331 L-2007-067, Attachment 1, Page 2 of 3 largest 6.9-kV AC motor. At a minimum, at least one phase of the power cable to ground is meggered from the power source (local starter, MCC, load center, switchgear, etc...). For some larger motors, testing beyond the normal megger test continues so the polarization index may be calculated and/or all three phases of the cable may be meggered to ground and between phases. Poer distribution cables feeding distribution equipment (load centers, MCC, etc.) are tested during the periodic scheduled maintenance of the subject distribution equipment by megger test phase to ground.
St. Lucie Units 1 and 2, Docket Nos. 50-335 and 50-389 Turkey Point Units 3 and 4, Docket Nos. 50-250 and 50-251 Seabrook Station, Docket No. 50-443 Duane Arnold Energy Center, Docket No. 50-331 L-2007-067, Attachment 1, Page 3 of 3 dabiU iniuhll iiuil.
TiALE i Cable Date of Type of Manu-Cable Shield Voltage Years of Energized/
Maintenance Under Cause of Reference Failure or Service facturer Type Class Service De-Rule ground Failure Document Testing energized St. Lucie #1 4/26/07 480V feeder Conax 1/C N/A 480V Installed in Continuously Yes No No Failure Condition Testing-to
- 250
- 1985, energized Report No.
10309A-SB Comment containment KCMil approx 22 under Low Meg-07-12838 (Containment
- 1 below fan cooler years normal plant Ohm penetration motor (HVS-operation reading feed-through 1 C)
- See cable)
Comment
- 1 below
- Comments:
1 The cable did not fail. A low Meg-Ohm reading on C Phase was identified during post-maintenance testing for the motor. Containment fan cooler HVS-1C was in operation prior to the start of refueling outage on 4/1/07. All 6 cables (two 250 KCMIL per phase) in the containment annulus feed-through will be replaced to prevent a potential future failure.
The cause of the cable's low Meg-Ohm reading is currently under investigation.
This annulus cable section is approximately 4 feet in length.
ATTACHMENT 2 TURKEY POINT NUCLEAR PLANT UNITS 3 AND 4 RESPONSE TO GENERIC LETTER 2007-01
St. Lucie Units I and 2, Docket Nos. 50-335 and 50-389 Turkey Point Ur its 3 and 4, Docket Nos. 50-250 and 50-251 Seabrook Station, Docket No. 50-443 Duane Arnold Energy Center, Docket No. 50-331 L-2007-067, Attachment 2, Page 1 of 3 TURKEY POINT NUCLEAR PLANT UNITS 3 AND 4 RESPONSE TO GENERIC LETTER 2007-01 INACCESSIBLE OR UNDERGROUND POWER CABLE FAILURES THAT DISABLE ACCIDENT MITIGATION SYSTEMS OR CAUSE PLANT TRANSIENTS NRC Reques: 1: Provide a history of inaccessible or underground power cable failures for all cables that are within the scope of 10 CFR 50.65 (the Maintenance Rule) and for all voltage levels. Indicate the type manufacturer, date of failure, type of service, voltage class, years of service, and the root cause for the failure.
FPL Response:
At Turkey Point, a records search indicates that within the scope of 10 CFR 50.65, there has been one AC power cable failure, one AC power cable that testing identified as degraded, and no DC power cable failures at Turkey Point. This determination was rendered through reviews of the condition report databases, Circuit and Raceway Schedule, and survey/interviews with plant personnel.
The cable fa lure involved 480 volt cable 4B0909/4B09-4FA1/1.
This is a feeder cable to a Traveling Screen Motor. The feeder cable was intermittently tripping the breaker. The cable was found to be damaged about five feet from the motor where the flex conduit connected to the embedded conduit which was in a deteriorated state of condition. The apparent cause of the cable damage was :he physical interface with the deteriorated conduit section. The screen wash system and the asscciated power source are not nuclear safety related and are not considered risk significant. However, the screen wash system is included in the Maintenance Rule Program due to its potential impact on the intake cooling water system and, therefore, is included in the results.
See AttachmE nt 2, Table 1, for the requested cable information.
The degraded cable involved 4160 volt power cable 4AA03/4AA03-4P1A/1.
This is the feeder cable from tho safety related 4160 volt switchgear to the steam generator feedwater pump motor.
The cable wa:; identified with a low, but acceptable, megger reading on one of the three conductors making up th_ C Phase, in 1994. The cable was replaced during the next refueling outage to prevent potential future failure. The portion of the cable routed underground was not removed for inspection / testing. The cause of the cable's low megger condition is not known. See Attachment 2, Table 1, for the requested cable information.
NRC Request 2: Describe inspection, testing and monitoring programs to detect the degradation (,f inaccessible or underground power cables that support emergency diesel generators (E DGs), offsite power, essential service water (ESW), service water, component cooling water and other systems that are within the scope of 10 CFR 50.65 (the Maintenance Rule).
St. Lucie Units 1 and 2, Docket Nos. 50-335 and 50-389 Turkey Point Ur its 3 and 4, Docket Nos. 50-250 and 50-251 Seabrook Statioii, Docket No. 50-443 Duane Arnold Energy Center, Docket No. 50-331 L-2007-067, Attachment 2, Page 2 of 3 FPL Response:
Turkey Point has a manhole inspection program that ensures manhole sump pumps/drains are working. ThE objective of this program is to provide assurance that systems, that are designed to minimize tie amount of time cable is exposed to a wet environment, are operational. The current inspection cycle is every 2 years for manholes where water was found during an inspection. The manholes without any water are inspected once every three years. Certain designated manholes are inspected under a hurricane preparedness program prior to each hurricane season.
In addition, covers of Appendix R manholes containing redundant safe shutdown cables are sealed to prevent the spread of flammable or combustible liquids into the manholes. The seals are inspected every three years.
Turkey Point does not have a formal program for testing and monitoring for degradation of inaccessible or underground power cables. However, periodic cable testing is done as part of the normal plant preventive maintenance program. Cables are tested as part of the normal preventative maintenance program for motors from the smallest Limitorque Motor Operated Valve to the argest 4-kV AC motor. At a minimum, at least one phase of the power cable to ground is me 3gered from the power source (local starter, MCC, load center, switchgear, etc...).
For some larger motors, testing beyond the normal megger test continues so the polarization index may be calculated and/or all three phases of the cable may be meggered to ground and between the phases.
St. Lucie Units 1 and 2, Docket Nos. 50-335 and 50-389 Turkey Point Units 3 and 4, Docket Nos. 50-250 and 50-251 Seabrook Station, Docket No. 50-443 Duane Arnold Energy Center, Docket No. 50-331 L-2007-067, Attachment 2, Page 3 of 3 Cable Information:
TABLE 1 Cable Date of Type of Manu-Cable Shield Voltage Years of Energized/ De-Maintenance Under Cause of Reference Failure or Service facturer Type Class Service energized Rule ground Failure Document Testing 4AA03/4A 1994 4.16kV General 1/C #750 Lead 5kV Original Continuously Yes Yes No Failure Condition A03-
- See feeder to Cable Lead Sheath plant cable energized Report No.
4P1A/1 Comment SGFWP
- Sheath,
-1973, 21 Low megger 94-1224
- 1 below Motor Butyl Years
- See Rubber Comment #1 Insulation below 4B0909/4 2/1997 480V N/A 2-1/C #12 N/A 600V Original Energized for Yes Yes Physical Spec B09-feeder to THW plant cable long periods of **See interface Clarification 4FA1/1 Traveling
- 1973, 24 time -
Comment #3 with
- E-012-097-Screen Years Considered below damaged 005 Motor continuously conduit energized
- See Comment #2 below
- Comments:
1 The cable did not fail. Low megger readings on one of the three conductors of C Phase was identified and the cable was replaced the next refueling outage to prevent potential future failure. The cause of the cable's low megger reading was not determined. The portion of the cable routed underground was not removed for inspection / testing.
2 The cable was damaged about five feet from the motor where the flex conduit connected to the embedded conduit which was in a deteriorated state of condition. The apparent cause of the cable damage was the physical interface with the deteriorated conduit section.
- 3. The screen wash system and the associated power source are not nuclear safety related and are not considered risk significant.
However, the screen wash system is included in the Maintenance Rule Program due to its potential impact on the Intake Cooling Water System.
ATTACHMENT 3 SEABROOK STATION RESPONSE TO GENERIC LETTER 2007-01
St. Lucie Units : and 2, Docket Nos. 50-335 and 50-389 Turkey Point Ui.its 3 and 4, Docket Nos. 50-250 and 50-251 Seabrook Statio:i, Docket No. 50-443 Duane Arnold Energy Center, Docket No. 50-331 L-2007-067, Attachment 3, Page lof 2 SEABROOK STATION RESPONSE TO GENERIC LETTER 2007-01 INACCESSIBLE OR UNDERGROUND POWER CABLE FAILURES THAT DISABLE ACCIDENT MITIGATION SYSTEMS OR CAUSE PLANT TRANSIENTS NRC Request 1: Provide a history of inaccessible or underground power cable failures for all cables that are within the scope of 10 CFR 50.65 (the Maintenance Rule) and for all voltage levels. Indicete the type manufacturer, date of failure, type of service, voltage class, years of service, and the root cause for the failure.
FPL Enerqy ;eabrook Response:
There have been no in-scope 10 CFR 50.65 inaccessible or underground power cable failures at Seabrook Station. This determination was rendered through reviews of the condition report database, work control database, and from interviews with cognizant design and plant engineering r ersonnel.
NRC Request 2: Describe inspection, testing and monitoring programs to detect the degradation of inaccessible or underground power cables that support emergency diesel generators (E DGs), offsite power, essential service water (ESW), service water, component cooling water and other systems that are within the scope of 10 CFR 50.65 (the Maintenance Rule).
FPL Enerqy,;eabrook Response:
As described in Seabrook Station Engineering Evaluation 94-41, "Submerged Electrical Cables and Supports," underground and inaccessible cable-monitoring program consists of three tests of representative power cables and a periodic manhole inspection for cable support condition and integrity. See Table 1 below for identification of cable loads, the test description and test frequency.
Table 1 Seabrook Station Cable Monitoring PMs Equipment ID Frequency Description of Task 1-CBA-UH-129-E 290-0000-000 96 Weeks Perform a Time-Domain Reflectometry (TDR) test to each (480 VAC motor zontrol center MCC-phase of cable CY6-J5J.
141 to disconnect switch for Control Building Unit Heter at J5J) 1-SY-CP-636-E290-0000-000 96 Weeks Perform a TDR test to each phase of cable E60-E64 (120/240 VAC Distribution panel E64 to termination ya d lighting panel E60) 1-ED-MCC-131-1:290-0000-000 96 Weeks Perform a TDR test to each phase of cable JJ3-WS1 (480 VAC termin 31 box WS1 to Switchyard Pow( r Receptacle JJ3) i-BM-MM-INSP-VIH-IE-000 10% of safety Perform 5 year inspection of supports in safety related related electrical manway enclosures.
manholes every 5 years
St. Lucie Units : and 2, Docket Nos. 50-335 and 50-389 Turkey Point Ui its 3 and 4, Docket Nos. 50-250 and 50-251 Seabrook Statio:i, Docket No. 50-443 Duane Arnold Energy Center, Docket No. 50-331 L-2007-067, Attachment 3, Page 2 of 2 Although not Dart of the formal monitoring program, some inaccessible or underground power cables are te,';ted as part of preventive maintenance on connected equipment. For example, underground power cables between the 4.16-kV and 13.8-kV busses and connected motors in Service Water and Circulating Water Systems are periodically insulation-resistance tested when motors are tested.
ATTACHMENT 4 DUANE ARNOLD ENERGY CENTER RESPONSE TO GENERIC LETTER 2007-01
St. Lucie Units : and 2, Docket Nos. 50-335 and 50-389 Turkey Point Ur its 3 and 4, Docket Nos. 50-250 and 50-251 Seabrook Station, Docket No. 50-443 Duane Arnold Energy Center, Docket No. 50-331 L-2007-067, Attachment 4, Page 1 of 1 DUANE ARNOLD ENERGY CENTER RESPONSE TO GENERIC LETTER 2007-01 INACCESSIBLE OR UNDERGROUND POWER CABLE FAILURES THAT DISABLE ACCIDENT MITIGATION SYSTEMS OR CAUSE PLANT TRANSIENTS NRC Reques: 1: Provide a history of inaccessible or underground power cable failures for all cables that are within the scope of 10 CFR 50.65 (the Maintenance Rule) and for all voltage levels. Indicate the type manufacturer, date of failure, type of service, voltage class, years of service, and t-ie root cause for the failure.
FPL Energy Duane Arnold Response:
There have bBen no in-scope 10 CFR 50.65 inaccessible or underground power cable failures at Duane Arn.)ld Energy Center. This determination was rendered through reviews of condition reporting date bases, work control database, and the Cable and Raceway database.
It should be n:ted that power cables have been damaged during construction and maintenance activities, mainly during digging operations. In those cases, the damage was either identified immediately c r during post maintenance testing. Since cables damaged during construction and maintenance activities were not placed in service, they were not considered failures for the purpose of th. response to Generic Letter 2007-01.
NRC Reques" 2: Describe inspection, testing and monitoring programs to detect the degradation cf inaccessible or underground power cables that support emergency diesel generators (EDGs), offsite power, essential service water (ESW), service water, component cooling water and other systems that are within the scope of 10 CFR 50.65 (the Maintenance Rule).
FPL Energy Duane Arnold Response:
Duane Arnold Energy Center inspects, on a quarterly basis, the electrical manholes that have a history of floo ling. The electrical manholes that have a history of flooding are those between the main plant anl the intake structure which have flooded during very wet springs and when the river floods.
Duane Arnold Energy Center does not have a program for testing and monitoring for degradation of inaccessibl or underground power cables. Some inaccessible or underground power cables are tested as part of preventive maintenance on connected equipment. For example, the 5-kV power cables between the main plant and the intake structure have the insulation resistance (megger) testad when the 4.16-kV / 480V transformers at the Intake Structure are tested. Power cables to mot)rs are also tested as part of the periodic insulation test of the connected motor.
FPL Energy Dluane Arnold is currently preparing a license renewal application. As part of the License Renewal Project, an Aging Management Program meeting the intent of NUREG 1801 Volume II XI.E;3 (Page XI E-7) will be developed and implemented.