ML20153B273
| ML20153B273 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 09/17/1998 |
| From: | Cruse C BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9809230045 | |
| Download: ML20153B273 (14) | |
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CuraLEs H. Ca0SE Baltimore Gas and Electric Company Vice President Calvert Cliffs Nuclear Power Plant Nuclear Energy 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 410 495-4455 September 17,1998 U. S. Nuclear Regulatory Commission Washington,DC 20555 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Response to Request for Additional Information for the Review of the Calvert Cliffs Nuclear Power Plant. Units 1 & 2. Commodity Reoort for Cables
REFERENCES:
(a)
Letter from Mr. C. H. Cruse (BGE) to NRC Document Control Desk, dated August 21,1997, " Request for Review and Approval of System and Commodity Reports for License Renewal" (b)
Letter from Mr. D. L. Solorio (NRC) to Mr. C. H. Cruse (BGE), dated July 9,1998," Request for Additional Information for the Review of the Calvert Cliffs Nuclear Power Plant, Units 1 & 2, Commodity Report for Cables" Reference (a) forwarded three Baltimore Gas and Electric Company (BGE) system and commodity j
reports for license renewal. References (b) forwarded questions from NRC staff on one of those three reports, the commodity report for Cables. Attachment (1) forwards our responses to the questions j
contained in Reference (b).
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9309230045 990917 I-PDR ADOCK 05000317 p
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Document Control Desk September 17,1998 Page 2 Should you have further questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours, 1/1
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STATE OF MARYLAND
- TO WIT:
COUNTY OF CALVERT I, Charles H. Cruse, being duly sworn, state that I am Vice President, Nuclear Energy Division, Baltimore Gas and Electric Company (BGE), and that I am duly authorized to execute and file this response on behalf of BGE. To the best of my knowledge and belief, the statements contained in this document are true and correct. To the extent that these statements are not based on my personal knowledge, they are based upon information provided by other BGE employees and/or consultants. Such information Las been reviewed in accordance with company practice and I believe it reliable.
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Sttbscyibed and sworn before me, a Notary fublic in and for the State of Maryland and County of
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.this l7[1]dayof /L6DAnllAJ998.
I WITNESS my Hand and Notarial Seal:'
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Attachment:
(1) Response to Request for Additional Infonnation; Integrated Plant Assessment Report for the Cables cc:
R. S. Fleishman, Esquire C.1. Grimes, NRC J. E. Silberg, Esquire D. L. Solorio, NRC S. S. Bajwa, NRC Resident Inspector, NRC A. W. Dromerick, NRC R. I. McLean, DNR H. J. Miller, NRC J. H. Walter, PSC
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ATTACHMENT (1) l RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES i
Baltimore Gas and Electric Company Calvert Cliffs Nuclear Power Plant September 17,1998
ATTACHMENT (1)
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RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES NRC Ouestion No.1 Since unscheduled cables (internal panel wiring, equipment pigtails and terminal wiring, field installed jumpers, and some non-safety-related cabling) are not in the cable raceway system (CRS) database, describe how these unscheduled cables are controlled.
BGE Response All cable purchased for installation at Calvert Cliffs Nuclear Power Plant (CCNPP) is given a cable cede. The cable code is included in the CRS database. Additionally, the installation of both scheduled and unscheduled cable is governed by Reference (1).
However, the cable installation may be " scheduled" or " unscheduled." The vast majority of plant cabling is installed in scheduled raceways. Scheduled raceways are trays and conduits that make up the plant raceway system designed for routing cables between connection points throughout the plant such that separation criteria are met and thermal limits are maintained. Cable installed in these raceways is scheduled; i.e., given a specific cable number and the specific routing is recorded in the CRS database.
Some cabling is run separate from the plant scheduled raceway system. Such unscheduled cabb is run in the field and a specific cable number is not recorded in the CRS database. However, the cable is run per the plant cable installation standard. Unscheduled cables include:
Local wiring segments beyond the scheduled raceway system, including pigtails between i
J-Boxes and equipment terminations and wiring internal to control panels; Jumpers connecting equipment to the plant grounding system; and e
Plant lighting and communication cables run in unscheduled raceways.
e Our processes do not allow unscheduled cables to be routed in the scheduled raceway system.
The installation of all cables at CCNPP, whether scheduled or unscheduled, is controlled by the plant modification process.
In summary, the purchase and installation of all cable at CCNPP, whether s.heduled or unscheduled, is controlled by plant processes.
NRC Ove fla1%l Baltimore Gas and Electric Company (BGE) states that internal panel wiring at CCNPP is not exposed to high temperature / radiation levels; therefore, aging is not considered plausible. Describe the basis for this conclusion and the methods that were used to verFv that the temperature / radiation levels were such that
,anel wiring.
they would not affect the functionality of the ir n
BGE Response Control panels are located in areas where the normal service 60-year radiation dose is expected to be well below the threshold levels for the wiring insulation material. No in-scope control panels are located inside containment or in any other radiologically-challenging environments.
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ATTACHMENT (1)
RESPONSE TO REQUEST FOR ADI'ITIONAL INFORMATION; INTEGRATED P'. ANT ASSESSMENT REPORT FOR CABLES l
The following discussion applies to instrumentation and control (I&C) panels / cabinets, 4 kV switchgear, 480 Volt load centers, and 480 Volt motor control centers. The wiring in these l
panels / cabinets is cross-linked polyethylene (XLPE) or Tefzel. The limiting case for aging is XLPE.
l The 60-year service limiting temperature for XLPE is 182'F.
The internal wiring of open I&C panels and closed I&C cabinets is XLPE or Tefzel-insulated I&C service wiring. Ohmic heating of this wiring is limited. The maximum ambient temperature to which I&C panels is exposed is less than 123'F. The local ambient temperature to which the wiring of open I&C panels is exposed is the bulk ambient temperature. Since this is less than 123'F, which is well below the 60-year service limiting temperatures for the wiring insulation material, thermal aging is not plausible for the wiring of open I&C panels.
However, closed I&C cabinets are expected to result in the more challenging thermal environment due to potentially restricted convective cooling. Therefore, they are designed to protect internal devices from excessive temperatures when the cabinet is exposed to design ambient temperatures.
Forced ventilation is provided, if necessary. A typical internal thermal service limit is 140 F. This is well below the 60-year service limiting temperature for cabinet wiring. Therefore, thermal aging of wiring internal to I&C panels is not plausible at CCNPP.
Switchgear and load centers contain power devices and components and XLPE-insulated wiring.
These cabinets are subject to significant ohmic heating. However, such heating is factored into the design of the enclosure. Maximum internal service temperatures, set by ANSI C37.20,1969, could potentially exceed the 60-year service limiting temperatures for the wiring. However, BGE measured the maximum temperature rise inside switchgear and load centers in response to Information Notice 89-30, Supplement 1. The measurements revealed a maximum rise of 1l'C compared to the 65 C allowed by the ANSI Standard., The maximum internel temperature for switchgear or load centers at CCNPP is, therefore, limited to 130 F (110 F + 20'F). This is well below the 60-year service limits for the internal wiring. Therefore, thermal aging of wiring internal to switchgear and load centers is not plausible at CCNPP. Polyvinyl chloride boots are used to insulate bus splices in the switchgear.
These are subject to plausible aging and will need to be managed according to existing processes during the period of extended operation.
Service temperatures inside motor control centers can approach the 60-year service limiting temperatures for the internal polyolefin-insulated wiring. This wiring is subject to plausible aging and will need to be managed during the period of extended operation.
The NRC identified the issue of hot spots and communicated the is ue to the industry via Information Notice 89-30, Supplement 1.
Baltimore Gas and Electric Company reviewed this notice for applicability to CCNPP. Switchgear and load center temperature rise measurements were made.
Baltimore Gas and Electric Company determined that consequential hot spot problems were being addressed by plant modifications.
NRC Ouestion No. 3 Reference (3) states that mechanical stress (including vibration, bending of wire and manipulation, etc.)
was cited frequently as a cause for failure and occurs near the end devices or connected loade. Discuss why mechanical stress and installation damage were not considered to be plausible age-related l
degradation mechanisms (ARDMs)(Table 6.1-2) for CCNPP cabling.
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ATTACHMENT (1)
RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES BGE Response Mechanical stress is not considered a plausible aging mechanism for the following reasons:
Damap to cables during installation at Calvert Cliffs is unlikely due to standard installation practices, which include limitations on cable pulling tension and bend radius. Even though installation damage is unlikely, most (including all safety-related) cables are tested after installation and before operation. Failures induced by installation dame.ge generally occur within a short time after the damaged cable is energized. Therefore, installation induced damage is not considered an aging mechanisn. for cabling at CCNPP.
Please refer to NRC resolution of License Renewal Issue No. 98-0013, Reference (6), which states,
" Based on the above evaluation, the staff concludes that the issue of degradation induced by human activities need not be considered as a separate aging effect and should be excluded from an aging i
management review."
Mechanical stress due to forces associated with electrical faults is mitigated by the fast action of circuit protective devices at high currents. However, mechanical stress due to electrical faults is not considered an aging mechanism since such faults are infrequent and random in nature.
Vibration-induced degradation is not a cable issue, but rather a connection issue. Loosening of connections is addressed in Section 6.2 of the License Renewal Application (LRA).
Manipulation of cables is not considered an aging mechanism since such manipulation occurs during maintenance activities. Such activities require post-maintenance testing to detect any deficiencies in the cables. Any evidence of cable abnormalities would result in initiation of the plant's corrective action program.
NRC Ouestion No. 4 The miscellaneous insulation cables listed in Table 6.1-1 (veador supplied turbine supervisory cables of unknown insulation material) have been determined by BGE as not subject to plausible aging since they are not subjected to high temperatures or radiation. Since the insulation material is unknown, what is the technical basis for this conclusion since the thermal rating of the material insulation is unknown to BGE7 FGE Responic These cables are not subject to significant radiative or thermal aging stress. They are run between the main Control Room and the 27-foot cable spreading room. These spaces are air-conditioned and the design normal radiation level is not elevated above background. Even if we assume the worst case, polyvinyl chloride insulation, with a 60-year service limiting temperature of 112 F, there is no plausible aging associated with these cables.
NRC Ouestion No. 5 The information provided in Table 6.1-1 that explains why the Kapton cables were excluded from the scope of the license renewal review is not adequate for the staff to conclude that there is sufficient justification for their removal. Provide additionaljustification for excluding the Kapton cables from the scope of the aging management review. Additionally, describe any other functions that are performed by
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ATTACHMENT (1)
RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES the Kapton cables beyond detection of heat or fires (for example, initiation of sprinkler system for fire suppression).
BGE Response At CCNPP, Kapton covered cabling is routed through cable trays and forms the sensing element of a portion of the Containment fire detection system. As such, the cable segments are given fire protection device numbe-The cable segments form a single circuit with send and return wires routed together, and separated by heat sensitive material with spring pressure between the conductors.
Fire or temperatures in excess of 280'F would cause the heat sensitive material to melt. The resulting short initiates an alarm and the fire detection system defines the affected zone. No fire suppression is automatically initiated as a result. In this special cable case, the license renewal function is the active function of circuit interruption, and the Kapton covering does not provide the insulation functions of dieleuric strength or insulation resistance. The covering serves as ajacket.
Therefore, these cables are not subject to aging management review.
NRC Ouestion No. 6 For the age-related degradation inspection (ARDI) programs credited for managing the ARDM affecting the Group 1,2,3, and 6 cables, provide a status summary on the development of the ARDI program elements for these groups.
BGE Response In our LRA, we indicated that the electrical cable ARDI was in progress. A summary of the status of that program is provided below. The purpose of the ARDI is to identify the population of cables that are subject to plausible aging and, therefore, require aging management. The ARDI is complete. The following discusses the results relative to Groups 1,2,3, and 6.
Group 1 cables were subjected to a temperature survey program. See the answer to Question No.7 l
below.
l Group 2 cables were subjected to analysis. See the answer to Question No.9 below.
l Group 3 cables were identified by application of a screening criteria designed to capture any cables that were potentially subject to synergistic radiative and thermal aging. Any power cables that l
satisfied all of the following criteria were considered subject to plausible synergistic radiative and l
thermal aging:
Inside containment; Insulated with ethylene-propylene rubber (EPR) or XLPE; In the scope of License Renewal; and Not environmentally qualified (EQ).
e Group 6 cables were identified by application of the following screening c'iteria. Any power cables that satisfied all of the below listed criteria were considered subject to plausible treeing:
Operating at 4kV service voltage; 4
ATTACHMENT (1)
RESPONSC TO REQUEST FOR ADDITION % INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES In the scope of License Renewal; Continuously energized; and Subject to an electrical stress of at least 35V/ mil.
Criterion (4) for Group 6 was selected to agree with that used by the Westinghouse Owner's Group work on cable aging relative to treeing. Initially, this limir was set at 35V/ mil, but has since been updated to 100V/ mil. Baltimore Gas and Electric Compai.y as,rees that such a change is warranted and has also chenged its limit to 100V/ mil.100V/ mil is appro@nately 10% of the inherent dielectric withstand capability of organic polymer insulations. No cables are found to be subject to plausible treeing at CCNPP when the new Group 6 criterion (4) is applied. This group will t.c. deleted when the LRA undergoes its first annual update.
NRC Question No. 7 Baltimore Gas and Electric Company states that the possibility exists that some Group I cable operating temperatures may sometimes exceed the insulation temperature rating of 90 C and a temperature survey program is being developed to establish an upper bound on the operating service temperatures.
a.
Discuss how BGE will collect temperature over sufficient time to capture peak cable service conditions given the variation in ambient temperature due to daily, seasonal, or operational effects.
- b. Because the maximum allowable material temperature for insulation is fixed, describe how BGE will account for the entire temperature history for Group I cables whose service limiting temperatures may have been exceeded.
- c. The EPR data sets were based on a 20% retention of elongation in BGE's use of the Arrhenius model to calculate 60-year service limiting temperatures. Since 50% retention of absolute elongation is the industry standard, justify why 20% retention of elongation is acceptable for cables with EPR insulation.
BGE Response Please note that the 90 C limit, cited in Part (b) of this request for additional information, is not the maximum allowable material temperature for the cable insulation. A cable with a 90 C insulation rating can be operated in excess of 90 C for a short time. Insulated Cable Engineers Association ICEA-S-66-524/ National Electrical Manufacturers' Association NEMA-WC7 and ICEA S 516/ NEMA-WC8 both describe " emergency overload" temperature ratings in excess of maximum operating temperature limits. Furthermore,90 C insulation rating does not equate to a particular service life. A service limiting temperature for any given time period is calculated by applying Arrhenius modeling of data sets based on the degradation of material properties. Therefore, the temperature survey prngram implemented by BGE wcs developed to determine an annual equivalent temperature that could then be compared to the 60-year service limiting temperature for the insulation material. The 60-year service limiting temperatures were.less than or equal to 90 C. Baltimore Gas and Electric Company chose to use 90 C for the 60-year service limiting temperature for silicone rubber insulated cables, even though analyses support the use of a much higher limit.
Group 1 is the set of power and control cables that are routed together in trays without maintained spacing. The ARDI was used to determine if any Group 1 cables were operating above the 60-year service limiting temperature. A set of candidate thermally-bounding locations for c.allecting service
ATTACHMENT (1)
RESPONSE To REQUEST FOR ADDITIONAL INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES temperature data were identined by analysis. This set was examined by infrared thermography to ensure that the bounding locations were identiSed and selected for service temperature monitoring.
The selection process considered ohmic heating, bulk ambient temperatures, external radiant heat sources, tray covers, etc. The thermally-bounding locations were instrumented and data was collected during approximately one year of plant operation. This length of time provided data that would include the effects of seasonal ambient tem [wature fluctuations as well as circuit cycling associau.d with normal operation.
Six trays were instrumented with recording thermistors to collect data on cable mass temperature.
The actual location within the cable mass was selected after probing the cable mass with a digital thermometer for the highest local temperatuie. The data (1800 temperature data points) was collected during the period between June 1996 and July 1997. The highest peak, average, and median temperatures were recorded for tray 2TE19 in the Turbine Building. This tray had the highest recorded difference between the tray surface temperature and ambient while being exposed to radiant heating from nearby steam piping.
An annual equivalent temperature was developed for EPR and XLPE insulations using the 2TE19 data and the methodology from Reference (7), Section AS.2. The EPR case was limiting and yielded the highest annual equivalent temperature. This temperature was less than 149 F and included a 17 F temperature rise through the insulation. Thus, a 35'F margin exists between the limiting case and the 60-year service limit for EPR of I84 F (184*F - 149 F = 35 F).
j Please note that Unit I was shut down during the infrared thermography survey portion of this ARDI.
However, the Unit I tray expected to exhibit the worst operating service temperature based on tray 611 and exposure to external radiant heating was instrumented.
Based on analysis of data collected from the thermally-bounding locations for Group 1, no Group I cables are subject to plausible aging. Please note that, as expected, the peak reccrded temperature (174*F) was well below 90 C (194 F).
Although 50% retention of absolute elongation is a common aging endpoint for EQ cables, it is not an industry standard. Furthermore, this portion of the LRA deals with non-EQ cables. Such cables do not need to function when subjected to a harsh design basis event-induced environment. Research has shown that degradation of insulation material mechanical properties precedes any degradation of electrical properties. Although 20% retention of elongation may not provide suf0cient margin for EQ service, it provides considerable margin for non-EQ applications.
NRC Ouestion No. 8 Describe the acceptance criteria for the CCNPP Cables ARDI program in Groups 3 and 6 that will ensure corrective actions that will be taken such that there is reasonable assurance that the prevention or isolation of faults in an electrical circuit intended function will be maintained.
BGE Response See BGE response to Question No. 6. The purpose of the ARDI is to identify cables subject to plausible aging. Baltimore Gas and Electric Company assumes that this question concerns the subsequent aging management program for those cables in these two groups that are found to be 6
ATTACHMENT (1) i RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES subject to plausible aging. As noted in the response to Question No. 6 above, Group 6 has been eliminated. The following discussion applies to Group 3.
l In accordance with Reference (8), as described in Section 6.1.3 of the LRA, corrective action has been initiated to address the management of aging of Group 3 cables. These cables will be replaced before the period of extended operation with new cables. The new cables will have identical or better aging characteristics. Since these new cables will be installed in the same environment and will not be called upon to operate for any longer than the demonstrated useful life, there is reasonable assurance that the new cables will not fait during the period of extended operation.
Replacement, as described above, is BGE's cable aging management program for this group.
However, if a condition nnaitoring program is developed to monitor remaining cable life prior to replacement, then BGE reserves the right to approach the NRC for relief from this commitment to replace these cables in favor of implementation of the condition monitoring program. Such a condition monitoring program is currently nonexistent, and BGE is unaware of the existence of any such program with industry or regulatory consensus.
NRC Ouestion No. 9 Describe the analysis that BGE has performed to verify that none of the operatmg temperatures for the Group 2 cables exceed the 90 C insulation rating.
BGE Response Group 2 cables are power cables routed with maintained spacing. Analysis was used to determine an upper bound on the operating service temperature for each cable. The analysis is based on two inputs, the design maximum ambient temperature as reflected in plant documentation, and the calculated maximum temperature rise for the cable. The analysis is described below.
The routing of each cable was reviewed to determine the spaces through which the cable passes.
Reference (2), containing radiation doses and ambient temperatures associated with plant spaces, was consulted to determine the " normal" design ambient temperatures to which the cable is exposed. The highest normal design ambient temperature, as reflected in ES-014 for all spaces through wnich the cable passes, was selected for use in the analysis. For example, if a cable passed through spaces with
" design maximum" temperatures of 104 F and 123 F, then 123'F would be used for the ambient temperature seen by the cable.
Note that this temperature is a design maximum temperature and actual temperatures are expected to be less. The design maximum temperature is used in specifying or qualifying equipment for use in the area. Normal here refers to non-design basis event conditions. Therefore, the ambient temperature selected in the analysis is higher than the cable will ever see for non-design basis event service.
A maximum temperature rise is calculated for the cable. This temperature rise is calculated using the method reflected in Reference 1 of Insulated Power Cable Engineers Association Standard IPCEA-P-46-426. Calvert Cliffs' cabling practices allow a cable to be loaded to 80% of the P-46-426 rated ampacity. This loading is assumed in the subsequent analysis to determine the temperature rise due to ohmic heating. The maximum design ambient temperature to which the Group 2 cables are exposed is 123*F. When minimum allowed cable spacing is (1/4) diameter, then the operating service 7
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ATTACHMENT (1)
RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES j
ambient temperature used in the analysis is adjusted to reflect local cable-cable heating effects. The temperature rise above the maximum design ambient temperature or the adjusted bulk ambient temperature is the calculated maximum temperature rise for the cable.
The calculated operating service maximum temperature was then compared to the 60-year service limit. If a 10 C margin between the 60-year service limit and the calculated operating service maximum temperature is not indicated, thermal aging is deemed plausible.
For example, 500MCM, (1/4) diameter spaced,480 Volt service cables:
A Design Maximum Bulk Ambient Temperature 50.5* = 123 F B
Adjusted Local Ambient Temperature (adjusted for radiant 66.9 C = 152.4 F heating from adjacent cables operating at 90 C (1/4) diameter away)
C Cable Conductor Temperature using method from Reference 88.3'C = 190.9'F I to IPCEA P-46-426 D
Temperature Rise (C-B) 21.4*C = 38.5*F 1
Please note the following conservatisms incorporated into this analysis:
- 1. The ambient temperature used in the analysis is the design ambient temperature, which is higher than the actual ambient temperature to which the cable is exposed;
- 2. The analysis uses a constant maximum ambient temperature, which does not reflect daily and seasonal variations that result in a lower annual equivalent temperature;
- 3. He cable is assumed to be loaded to the mr.ximum allowed level;
- 4. A 100% duty cycle is assumed; i.e., no credit is taken for off-load periods; and
- 5. A 10'C margin is required to be indicated by the analytical results.
Some cables were found to be subject to plausible thermal aging during 60-years of plant service.
None of the calculated maximum service temperatures were found to exceed the 90C limit.
NRC Ouestion No.10 As discussed in the Group 1 Aging Mechanism Effects section, the 60-year service limiting temperature was determined to be 184 F for EPR insulation. However, Reference (1) lists the maximum ambient temperature for EPR insulation at 167 F for cables with no ohmic heating based on 50% retention of i
absolute clongation. Provide the basis for the 184 F EPR maximum ambient temperature rating selected by BGE.
BGE Response The 60-year service limiting temperature of 184*F for EPR used at Calvert Cliffs was developed as follows: System 1000, an industry material characteristics database since incorporated into the Electric Power Research Institute-sponsored and NUS Corporation-managed EQ database (EQDB) was consulted. That database contained 20 sets of data for EPR material applicable to insulation service, ne activation energies ranged from 1.05 eV to 1.56 eV. It was determined that one entry corresponded to Kerite used at Calvert Cliffs. The activation energy for this set is 1.06 eV based on 20% retention of elongation. As previously discussed, 20% retention of clongation provides 8
l ATTACHMENT (1)
RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES considerable margin for non EQ service. Linear regression was applied to this data set to develop an Arrhenius model. The model was then used to calculate the 60-year service limiting temperature for EPR in use at Calvert Cliffs.
To check the validity of using this figure in our analyses, a comparison was made to 60-year service limiting temperatures calculated from onsite EQ file information. A comparison to EQ data provides a check on the representativeness of the 60-year service limiting temperature determined as above.
The comparison indiccted agreement with the EQ file data.
Please note the following conservatisms in this approach:
'Ihe data set yielding the fastest aging representative of Calvert Cliffs EPR cabling was selected; and A 20% retention of elongation is used for non-EQ service.
e NRC Ouestion No.11 Baltimore Gas and Electric Company states that cable condition monitoring is presently considered an 1
optional approach to ongoing cable management and that they will monitor research in this area. Discuss j
to what extent BGE considers the following physical properties when inspecting cable systems as part of a cable condition monitoring program.
Surface condition (including cracking, crazing, texture);
l Color; e
Size (swelling, shrinkage, deformation, or compression set);
e Physical integrity (tight or loose); and Flexibility or embrittlement (requires manipulation in accordance with an inspection procedure).
)
BGE Response The character of an acceptable cable condition monitoring program is currently undefined by the industry. Active research on cable condition monitoring is ongoing and BGE is monitoring this research. However, BGE has no current cable condition monitoring program. Furthermore, BGE has not defined the attributes of a future cable condition monitoring program. Nonetheless, whenever plant maintenance personnel discover any abnormal conditions, they report those conditions for further evaluation and action if needed. This attention to detail resulted in the discovery and correction of a termination overheating problem.
The following summarizes the cable aging management programs for which BGE seeks credit.
Group 1 cables are not subject to plausible aging. Group 2 and 3 cables are subject to plausible aging that will be managed by replacement. Baltimore Gas and Electric Company's approach to cable replacement is discussed in the response to Question No. 8. Group 4 cable terminations are subject to plausible aging that will be managed by the CCNPP Electrical Preventive Maintenance (EPM)
Program. Group 5 cables are subject to plausible aging that will be managed by the CCNPP Instrument Calibration Program. There are no cables remaining in " treeing plausible" Group 6.
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' A'ITACHMENT (1) l RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES NRC Ouestion No.12 Group 3 power cables inside containment with EPR or XLPE insulation are subject to synergistic thermal and radiative aging. To manage the effects of synergistic radiative and thermal aging for the Group 3 cables, BGE stated that it will develop a new ARDI plant program to provide monitoring, testing, and analysis. One of the ARDI elements is condition monitoring (i.e.,in-situ non-destructive testing).
Describe the non-destructive testing that BGE is planning with regard to cable condition monitoring.
BGE Response Baltimore Gas and Electric Company is not cu rently planning any testing as part of a condition monitoring program to manage Group 3 cables. He replacement program described in the response to Question No.8 is the aging management program for which BGE seeks credit.
NRC Ouestion No.13 The Group 4 power cables with EPR insulation that are associated with the Saltwater System and Service Water System 4kV pump motors are subject to thermal degradation of the motor terminations.
Baltimore Gas and Electric Company states that the existing EPM program will be modified and will include visual inspection as part of the periodic EPM on the pump motors. Provide a summary discussion of the modifications intended, including the applicable inspection criteria for the cables that will be included in the revised EPM che:klists.
BGE Response The following is proposed for addition to the Preventive Maintenance Program:
Inspect motor terminations for signs of overheating including discoloration, crazing, cracking, and local embrittlement at the termination point. Report any abnormal conditions to the system engineer for disposition.
This is " draft" wording and final wording is subject to plant approval processes.
NRC Ouestion No.14 The Group 5 EPR/XLPE/ cross-linked polyolefin instrumentation cables that are subject to insulation resistance reduction effects from thermal and radiation-induced degradation of the cable insulation will be managed by the existing Instrument Calibration Program, MN-1-211. Describe the corrective actions that '.ure taken to correct the two weaknesses identified by NRC inspections in 1986,1991, and 1992 related to: (1) program inconsistencies that did not permit a readily accessible mechanism to ensure safety-related process instrumentation was scheduled and periodically calibrated; and (2) there was no process to evaluate the effect of equipment operability ofinstrumentation found out-of-calibration.
BGE Response Please refer to Reference (9), Section 4.3.a, which notes that BGE has corrected the deficiencies cited in Combined Inspection Report 50-317/50-318/93-23 and as noted in your question.
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ATTACHMENT (1)
RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION; INTEGRATED PLANT ASSESSMENT REPORT FOR CABLES NRC Ouestion No.15 The Group 6 4kV power cables with EPR insulation are subject to voltage-induced degradation of the cable insulation known as ' treeing' which will be managed by a new plant program consisting of monitoring, testing, and analysis.
Describe the in-situ non-destructive testing (cable condition monitoring) that BGE is planning to use to detect the effects of' treeing' which can lead to an eventual breakdown of the insulation dielectric strength.
BGE Response Group 6 has been eliminated as noted in the response to Question No.6 above. Therefore, a program to manage the effects of treeing is no longer required.
References 1.
CCNPP Plant Cable Installation Standard, E-406 2.
CCNPP Engineering Standard, ES-014, Summary of Environmental Service Conditions 3.
Department of Energy Contractor Report SAND 96-0344, " Aging Management Guideline for Commercial Nuclear Power Plants - Electrical Cable and Terminations," September 1996
)
4.
Electric Power Research Institute Report NP-4172SP, Radiation Data for Design and Qualification of Nuclear Plant Equipment 5.
Calvert Cliffs Aging Management Report for Cables (Phase 1) 6.
Letter from Mr. C. I. Grimes (NRC) to Mr. D. J. Walter (NEI), dated June 5,1998,
" Degradation Induced Human Activities"
~ 7.
Electric Power Research Institute Technical Report No. TR-100516, " Nuclear Power Plant Equipment Qualification Reference Manual," 1992 8.
CCNPP Directive QL-2," Corrective Actions Program," Revision 2, January 2,1996 9.
Letter from Mr. C. J. Cowgill (NRC) to Mr. R. E. Denton (BGE), dated June 14,1993, NRC Region 1 Resident Inspection Report Nos. 50-317/93-13 and 50-318/93-13 (April 25,1993 -
May 29,1993) 11