ML20236L677

Safety Evaluation Approving Wepco Implementation Program to Resolve USI A-46 at Point Beach NPP Units 1 & 2

ML20236L677
Person / Time
Site:	Point Beach
Issue date:	07/07/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20236L673	List: ML20236L671 ML20236L677
References
REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR NUDOCS 9807130132
Download: ML20236L677 (10)

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. ,.s 1" UNITED STATES I g NUCLEAR REGULATORY COMMISSION {

p WASHINGTON, D.C. soseH001 l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l

ON THE WISCONSIN ELECTRIC POWER COMPANY l RESPONSE TO SUPPL FMENT NO.1 TO GENERIC LETTER 87-02 FOR THE POINT BEACH NUCI FAR PLANT )

)

UNITS 1 AND 2 l

l DOCKET NOS.: 50-266 AND 50-301 1

1.0 ItiTRODUCTION

! On February 19,1987, the NRC issued Generic Letter (GL) 87-02, " Verification of Seismic Adequacy of Mechanica' and Electrical Equipment in Operating Reactors, Unresolved Safety l l lasue (USI) A-46." in the generic letter, the NRC staff set forth the process for resolution of USl A-46 and encouraged the affected nuclear power plant licensees to participate in a generic )

program to resolve the seismic verification issues associated with USl A-46. As a result, the Seismic Qualification Utility Group (SQUG) developed the " Generic Implementation Procedure ,

(GlP) for Seismic Verification of Nuclear Plant Equipment," Revision 2. I

[ On May 22,1992, the NRC issued Supplement 1 to GL 87-02 including the staff's i Supplemental Safety Evaluation Report No. 2 (SSER-2) (Reference 1), pursuant to the l provisions of 10 CFR 50.54(f), which required that all addressees provide either (1) a commitment to use both the SQUG commitments and the implementation guidance described ,

in GIP-2 as supplemented by the staff's SSER-2, or (2) an attemative method for responding to GL 87-02. The supplement also required that those addressees committing to implement l GIP-2 provide an implementation schedule as well as detailed information including the l procedures and criteria used to generate the in-structure response spectra (IRS) to be used for USl A-46.

In a letter dated September 21,1992 (Reference 2), Wisconsin Electric Power Company, the licensee, provided its response to Supplement 1 to GL 87-02 for the Point Beach Nuclear Plant Units 1 and 2. In this letter, the licensee committed to follow the SQUG commitments set forth in

' GIP-2, including the clarifications, interpretations, and exceptions identified in SSER-2. The staff issued its evaluation of the licensee's response by letter dated February 22,1993 (Reference 3).

By letter dated June 30,1995 (Reference 4), Wisconsin Electric submitted summary reports for both unh of Point Beach containing the results of the USl A-46 program implementation at the plant. 6 Y.ters dated September 30,1996 (Reference 6) and July 31,1997 (Reference 7), the licensee provided supplemental information and clarification in response to the staff's requests ENCLOSURE 9807130132 980707 PDR ADOCK 05000266 i p PDR l

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for additional information (RAls), dated May 23,1996 (Reference 8) and May 16,1997 (Reference 9), respectively.

This report provides the staffs evaluation of the licensee's USI A-46 implementation program based on the staffs review of the summary report, supplemental information, clarification, and documentation provided by the licensee in response to the staffs RAls.

2.0 DISCUSSION AND EVALUATION The staffs review of USl A-46 summary reports for Point Beach Units 1 and 2 (Reference 4)

- was performed in accordance with the USI A-46 Action Plan, dated July 26,1994. In this regard, the effort consisted of a screening level review of specific sections of the licensee's program, with emphasis placed on identification and resolution of outliers, i.e., equipment items that did not readily pass the GIP-2 screening and evaluation criteria. The summary report describes a safe shutdown path and provides the evaluation of seismic adequacy of tanks and heat exchangers, cable and conduit raceways, relays, and outlier identification and resolution including proposed schedules.

2.1 Seismic Demand Determination In 1993, the staff reviewed and approved the licensee's proposed ground acceleration input and resulting IRS (Reference 3). The input motions used for the plant structural design is based on the Housner Ground Response Spectrum which is the plant design-basis spectrum. The spectrum is scaled to 0.06g for the operating bases earthquake (OBE) and 0.12g for the safe shutdown earthquake (SSE) of the horizontal components of motion. Two-thirds of the >

horizontal spectrum was used for the vertical component of motion. The licensee developed IRS using the 1949 Olympia, Wa;hington, time-history normalized to 0.06g. The resulting IRS was multiplied by 2 to arrive at u9 SSE-IRS. The staffs review also found that the design-basis ground spectra and resulting IRS are considered conservative spectra for the purpose of the USI A-46 resolution. Subsequently, in response to the staffs RAI, the licensee l

stated (Reference 5) that the Point Beach Nuclear Plant IRS which was used for the USl A-46 Seismic Verification Project is the same as those provided to the NRC by Wisconsin Electric in l the September 21,1992, submittal (Reference 2). The staffs review confirmed the licensee's

! statement. The licersee established the seismic demand for equipment in the safe shutdown equipment list using the approved GIP-2 methodology and, therefore, it is adequate and acceptable.

I 2.2 Seismic Evaluation Personnel The licensee has provided the information conceming the qualification and experience of the seismic evaluation personnel. The system engineers developed the safe shutdown equipment list (SSEL) and assisted the seismic review team (SRT) and the relay evaluation personnel responsible for evaluation of relay chatter and identification of electrl cal SSEL components.

The staff found that the seismic capability engineers who were members of the SRT and the system engineers, possessed considerable experience in design and analysis and met the qualification and experience requirements of GIP-2 and, therefore, are acceptable.

3-2.3 Safe Shutdown Path 1

GL 87-02 specifies that the licensee should be able to bring the plant to, and maintain it in, a hot shutdown condition during the first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following an SSE. To meet this provision, in its submidal of June 30,1995, (Reference 4), the licensee addressed the following plant safety functions: reactor reactivity control, pressure control, inventory control, and decay heat removal. Primary and attemate safe shutdown success paths with their support systems and l instrumentation were identified for each of these safety functions to ensure that the plant is capable of being brought to, and maintained in, a hot shutdown condition for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following an SSE. Appendix F of the submittal (Reference 4) provides the SSEL.

The reactor decay heat removal function is accomplished by the secondary system using steam generators (SGs) and SG safety valves. The auxiliary feedwater (AFW) system provides the makeup feedwater to SGs to maintain the primary-to-secondary heat transfer capability. The normal supply for makeup feed water to the AFW pumps is the condensate storage tank which is not seismic class 1. The seismic class 1 makeup water supply source for the AFW pumps is the service water system. The feedwater supply switchover can be accomplished by the plant operators within 5 minutes, thus maintaining the minimum SG water levels required for decay  ;

heat removal. Lake Michigan is the source of service water. The plant Operations Department reviewed the equipment listed in Appendix F against the plant operating procedures and  ;

concluded that the plant operating procedures are adequate to establish and maintain the plant  !

in a safe shutdown condition following an SSE. The staff concludes that the approach to achieve and maintain hot shutdown for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after a seismic event is acceptable.

2.4 Seismic Screenino Verification and Walkdown for Mechanical and Electrical Eauinment 2.4,1 Eauioment Seismic Canacity Comoared to Seismic Demand i

Table 4-1 of the Generic Implementation Procedure, Revision 2 (GIP-2) lists two methods for l comparing equipment seismic capacity to seismic demand. Method A requires a comparison of  !

the SSE ground response spectra to the GIP-2 Bounding Spectrum or the Generic Equipment Ruggedness Spectra (GERS). Method B requires a comparison of the in-structure response spectra against 1.5 times the Bounding Spectrum or the GERS for the equipment. To use method A, the equipment should be mounted within about 40 feet above the effective grade, the equipment natural frequency should be greater than about 8 Hz, and the amplification factor between the free-field response spectra and the IRS will not be more than about 1.5. Method B may be used for equipment at any elevation and for equipment with any natural frequency.

( in response to a staff RAI, the licensee stated (Reference 9) that only 2 out of the 62 equipment l items were evaluated using method A. The justification for using method A for these two pieces of equipment (1SI-866A and 1SI-866B; class 8 equipment, Motor-Operated Valves) was provided based on equipment caveats. " Caveats" are defined as the set of inclusion and exclusion rules that represent s'weific characteristics and features particularly important for seismic adequacy of a particular class of equipment ( Reference 4). A further discussion on

" caveats" is provided in Section 2.4.2 ' Assessment of Equipment Caveats." The staff found the licensee's assessment of the adequacy of equipment seismic capacity reasonable and acceptable.

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2.4.2 Assessment of Eauioment Caveats During performance of the walkdown screening and seismic adequacy evaluation, the licensee 1

( did not identify significant deviations from GIP-2. Very few interpretations were made with  !

L respect to the wording of GIP-2 caveats'versus the intent of the caveats. The licensee 1 l

' identified the equipment that did not meet the rules of the caveats and their resolution in Table l 5.1 of the summary report. The staff did not identify discrepancies with the licensee's I assessment of equipment caveats.

l 2.4.3 . Eauioment Anchoraces 1

i The licensee stated (Reference 4) that the evaluation of equipment anchorages for the Point Beach plants is in accordance with the guidance provided in GlP-2. All accessible anchorages were visually inspected. Examples of the findings included (1) transformers were found anchored by friction clips, an unacceptable form of anchorage according to GIP-2, (2) a reactor l trip breaker cabinet was found unanchored, and (3) inverters and battery chargers were found not bolted together. They were classified as outliers. 1 In addition to equipment anchorages visual inspection, anchorage capacities for some equipment were determined and compared with the respective seismic demand. Anchorages for which capacity was found to be less than demand were classified as outliers.

All of the outliers, for Equipment Classes 1 through 21, are shown in Table 9-1 of the summary report (Reference 4). The discussion on resolution of outliers provides a summary of the seismic operability determination and in-progress or proposed resolutions. The staff finds the licensee's action regarding equipment anchorages to be reasonable and acceptable.

2.4.4 Seismic Soatial Interaction Evaluation During the Point Beach plant walkdown, the Seismic Review Team (SRT) identified several  !

potential interactions involving portable equipment, carts, bookcases, and computer printers (in

! the main control room). An air-operated valve in proximity to an unanalyzed block wall was also i noted. Section 9 of the summary report (Reference 4) discusses resolutions of identified outliers. I The licensee stated that overhead piping systems and duct work were closely examined in all I l

plant areas containing the USI A-46 equipment. The licensee further stated that the SRT

, identified no vulnerabilities involving piping and duct work and noted that the systems were well

! supported. The staff finds that the licensee's resolution of seismic spatial interaction aspect of the USl A-46 to be reasonable and acceptable.

2.5 Tanks and Heat Exchanoers The licensee stated (Reference 4 ) that most of the tanks and heat exchangers were evaluated in accordance with the rules and procedures described in Section 7 of GlP-2. In total,52 tanks and heat exchangers were evaluated and 6 of them were classified as outliers.

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The refueling water storage tank (RWST) did not meet the provisions of GlP-2 and was classified as an outlier. The tank was evaluated using the method proposed in Appendix H of Electric Power Research Institute (EPRI) Report NP-6041, Rev.1, " Flat Bottom Vertical Fluid Storage Tanks." The staff requested additional information regarding the use of Appendix H

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and the soil-structure interaction analysis which was used as the basis for resolution. The licensee, upon reviewing the issue further, informed the staff that the resolution of the RWST would be based on a structural modification rather than the acceptance criteria of Appendix H of EPRI Report NP-6041, Rev.1 (Reference 9). The staff accepts the licensee's resolution of the RWST. The remaining five tanks had some anchorage concems. Two out of the five tanks were reanalyzed using finite element analysis metFod and were found acceptable. For the remaining three tanks, the anchorages were upgraded by modification. The staff considers the resolution of each of the five tank outliers to be acceptable.

2.6 . Cable and Conduit Raceways The Point Beach raceway systems are primarily light steel strut frame construction. The predominant strut hanger type is the cantilever strut with brackets supporting cable trays or conduits. Lateral and longitudinal bracings are used in various systems. A considerable percentage of raceways are rigidly mounted on walls using a strut frame, bracket or single strut members mounted directly on the wall.

The licensee's evaluation was based on Section 8 of GIP-2. It consisted of a plant walkdown, identification of the worst-case supports, and a limited analytical review (LAR) per GIP-2.

Candidate raceway systems located at various elevations in major buildings were covered during the walkdown. The licensee stated that no missing or damaged hardware was noted.

In accordance with GIP-2, representative worst-case (bounding) samples ci the raceway supports were selected for LARs. The staff had identified a concern on an aspect of GlP-2 that was identified in the LARs (Reference 5). In particular, after vertical load checks, no lateralload checks are required by GlP-2 when the supports are judged to be ductile. A sigrJ'icant number of supports evaluated using the LARs were determined to be acceptable partly becouse of the ,

ductility determination. A total of three outliers, allin the cable spreading room, were .3dentified.

These three supports failed the tests for the vertical load capability. The licensee stamd during the telephone conversation with the staff on May 8,1998 (Reference 10) that the outliew pertaining to the above supports would be resolved by modifications scheduled to be cort,;Jeted by the fall of 1999, in addition, the staff performed a review of some LARs to determine if tt 9y conform with GIP-2 procedure for those supports determined to be acceptable. The staff nots d i that in three cases (LAR 001, LAR 007, and LAR 010), the affected raceway supports should have been classified as outliers since they were not similar to typical ductile supports addressed in GlP-2.

In total,10 supports were investigated using the LAR process; 3 were declared as outliers by l the licensee. Out of the remaining seven, the staff finds that 3 additional supports should have been identified as outliers resulting in 6 outliers out of 10 supports investigated. 'This finding leads the staff to conclude that the licensee, in some cases, may not have properly addressed the ductility issue in regard to raceway supports examined in the USl A-46 implementation program. However, due to the inherent ruggedness of raceway supports as evidenced from the 1

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, earthquake experience data, the staff considers the licensee's evaluation acceptable for the purpose of the USI A-46 program implementation.

5 2.7 Essential Relavs The licensee developed a list of 755 components from the SSEL that required a relay review.

The functional screening of the control circuits of the components identified 2370 relays which were included in the associated relay list (ARL). Of these relays,731 relays were screened based on acceptable chatter and 163g relays were screened as essential relays requiring seismic screening. The ossential relays were grouped into one of the following three categories:

e Seismic capacity vs. demand comparison involving 1461 relays e Application of switchgear rule-of-the-box involving 69 relays e Relays mounted on vibrating equipment such as air compressor and emergency diesel generator totaling 109 relays.

Of the total number of relays requiring seismic capacity vs. demand comparison,1329 relays were found to have adequate seismic capacity and the remaining 132 relays were identified as outfiers. Out of these 132 relay outliers,8 relays were identified as " bad actor" low ruggedness relays and 124 relays had unknown seismic capacity. The relay walkdown verified that the

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essenila! relays were traceable in accordance with applicable drawings and were properly -

installed. For contact devices such as relays, circuit breakers, etc., mounted on the vibrating equipment or contained in skid-mounted cabinets where the vibratory excitation caused by the  ;

operation of the vibrating equipment may be outside the frequency range of concem for the i seismic event, the licensee will perform a reevaluation of such contact devices. The staff finds that the licensee's evaluation of relays is generally acceptable in accordance with the  !

methodology specified in GlP-2.

2.8 . Fluman Factors Aspect i The staff's review focussed on verifying that the licensee's operations department had used one or mere of the GIF 2 methods for conducting the review of the SSEL, and had considered aspects of human performance in determining what operator actions could be used to achieve and maintain a safe shutdown (e g., resetting relays, manual operation of plant equipment).

The licensee provided information that outlined the use of a multi-disciplinary team for the evaluation of the SSEL and associated procedures. The team verified that existing normal, abnormal, arid emergency operating procedures were adequate to mitigate the postulated transient and that operators could place and maintain the plant in a safe shutdown condition.

The staff verified that the beensee had considered its operator training programs and auxiliary operator training programs and had verified that the training that was provided was sufficient to ensure that those actions specified in the procedures could be accomplished by the operating crews in the-time frame required. In addition, the staff requested verification that the licensee had adequately evaluated potential challenges to operators, such as lost or diminished lighting, harsh environmental conditions, potential for damaged equipment interfering with the operator's tasks, and the potential for placing an operator in unfamiliar or inhospitable surroundings. The licensee provided information regarding its seismic evaluations to substantiate that operators'

) , actions could be accomplished in a time frame required to mitigate the seismic event.

Locations of equipment that needed to be manipulated were verified by the I!censee to be in seismically designed buildings with ingress / egress pathways accessible from the control room. ,

The licensee also analyzed ambient environmental conditions and determined them to be -

adequate to ensure habitability of the areas should operator response be necessary. One potential outlier identified by the licensee was the air operated atmospheric steam dump valves (ADVs) which must be manually operated due to the presumed loss of the nonseismic instrument air system. The licensee verified that the ADVs were located at the Units 1 and 2 facade structures on a seismic platform attached to the exterior of the containment, and that the auxiliary operator's ability to access the ADVs would be maintained during the design-basis seismic event.

The licensee performed a technical evaluation of emergency lighting capability as part of the fire protection program. The results of that program ensured that emergency lighting required to locally operate equipment necessary to maintain a safe shutdown of the pitnt(i.e., SSEL) were seismically qualified and seismically mounted. The licensee has provided the staff with sufficient information to demonstrate conformance with the NRC-approved review methodology outlined in GIP-2 and is, therefore, acceptable.

2.9 Outlier Identification and Resolutions In the Summary Report (Reference 4),99 outliers were initially identified for Equipment Classes 1 through 21. Of these 99 outliers,57 outliers have been resolved either by modification, upgrade, or by analysis. Forty-two outliers remain to be resolved. For Equipment Class 22, Cable and Conduit Raceway review, 3 of the 101.ARs for cable tray supports v'ere identified as outliers. For raceway supports, the proposed resolution is based on two phases. Phase one will be to conduct an exploratory walkdown to determine if any possible analytical meihods cxist .

for resolving the outliers. The scope and time frame for follow on phases will depend on the '

results of the first phase (Reference 4). In addition to these, there were two outliers ascociated with cables hanging out of their respective cable trays in tne Unit 1 and Unit 2 containment buildings and one outlier associated with a locse base clip angle on a cable tray support in the Unit 1 containment building. The schedule for completion of resolutions to outliers is planned -

for the fall of 1999. In regard to the outlier pertaining to the RWST, tha licensee previously suggested performing structural modifications to the tank. Hcwever, during a telephone conversation on May 8,1998 (Reference 10), the licensee stated that an alternative option of replacement of the tank was being considered. Therefore, the completion schedule of the RWST outlier could not be established at the present time. For the r3lays, there are 132 relay outliers that required resolation. The licensee @ted during the telephone conversation on  ;

May 8,1998 (Reference 10) that all relay outliers except those pertaining to the diesel generators would be resolved by the fall of 1999. The licensee has planned to replace the '

controls for the diesel generators by the year 2002. The staff has determined that the licensee's identification and proposed resolution of outliers were, in general, consistent with the i guidelines of GIP-2 and the staffs SSER No. 2.

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1 3.0 SjgMeBY OF MAJOR STAFF FlNDINGS Based on the staff's evaluation of the various aspects of the licensee's USI A-46 g implementation program ss discussed above. the following findings are identided.  ;

g F (a) Tha licensee, in so:ne cases, may not have properly addressed the ductility it. sue in I- regard to raceway supports for cable trays and conduits ahd did not always foiiow the L provisions of G1P-2 in performing the raceway support evaluations.

fb) For relays contained in skid-mounted cabinets of vibrating equipments such as diesel generators and air compressors, the vibration of the skid should be compared with the h

input motion (e.g., SSE) to ensure that the mechanical vibration envelops the required

{- input motion. The licensee stated that it would reevaluate the seismic adequacy of these contact devices initially ecreened as seismically adequato based on the rule-f-the-box application to ensure that the vibratory excitation caused by the operation of the vibrating equipment is at least equal to the required seismic motion at that location and that the relays perform their intended functions during a postulated SSE event

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4.0 .GDNGUJSLQES w

1 in general, the licensee conducted the USl A-46 implementation in accordance with GlP-2. The I licensee's subrnittal on the USl A-46 implementation indicated that the SSEL contained 762 L components excluding heat exchangers and tanks and electrical raceways. Of this population,

?8 items were classified as outliers. An additional 21 outliers pertained to heat exchangers E and tanks and electrical raceways. According to the licensee,42 outliers out of a Mal of 99 7 would be resolved by the end of the Unit 1 outage, scheduled for the fall of 1999. In regard to

" relays,132 outliers would also be resolved by the fall of 1999. The licensee's implementation program did not identiff any instance whett the operability of a particular component was 5-questionable. The staff's review of the licensee's implementation program resulted in the f identification of two findings that are described in Section 3.0 of this report. The findings

" represent specific areas where the licensee's program did not meet certain provisions in GIP-2 and/or the staffs SSER No. 2 on SQUG/ GIP-2 issued in 1992. In one area relating to relays E contained in skicLmounted cabinets of vibrating equipment, the licensee committed to e -

s evaluate the seismic adequacy of the contact devices initially screened as adequate, k

5l The staff concludes that the licensee's USI A-46 implementation program has, in general, met 3 , the purpose and intent of the criteria in GIP-2 and the staff's SSER No. 2 for the resolution of USl A-46. The staff has determined that the licensee's already completed actions and i commitment to resolve the remaining outliers will result in safety enhancements, in certain aspects, that are beyond the originallicensing basia. As a result, the licensee's actions provide i . sufficient basis to close the USl A-46 review at the facility. The staff also concludos that its

, findings regarding the licensee's implementation of USI A-46 do not warrant any further g' regulatory action under the provisions of 10 CFR 50.54(f). Licensee activities related to the USl c A-46 implementation may be subject to NRC inspection.

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. Regarding future use of GIP-2 in licensed activities, the licensee may revise its licenslog basis l, ' in accordance with the guidance in Section 1.2.3'of the staff's SSER No. 2 on SQUG/ GIP-2, -

L 'and the staff's letter to SQUG's Chairman, Mr. Neil Smith, ori June 19,1998. The primary

considerations in the licensee's determination to incorporate gip-2 in the licensing basis are  ;

completion of commitments regarding equipment outlier resolution and/or modifications and '

resolution of allidentified staff review findings where the implementation program does not meet GlP-2 (summarized in Section 3.0). Where plants have speci'ic commitments in the licensing basis with respect to seismic qualification, these commitments should be carefully considered. The overall cumulative effect of the incorporation of the GIP-2 methodology, -!

considered as a whole, should be assessed in making a determination under 10 CFR 50.59. 1 An overall conclusion that no unreviewed safety question is involved is acceptable so long as 1 any changes in specific commitments in the licensing basis have been thoroughly evaluated in -

reaching the overall conclusion. If the overall cumulative assessment leads a licensee to conclude an unreviewed safety question is involved, incorporation of the GIP-2 methodology into the licensing basis would require the licensee to seek an amendment under the provisions l t of 10 CFR 50.90. i Principal Reviewers: S. B. Kim

' 'l P. Patnaik Date: Jul .7, 1998-

5.0 REFERENCES

1. Supplement No.1 to GL 87-02 that transmits " Supplemental Safety Evaluation Revision No. 2 on SQUG Generic implementation Procedure, Revision No. 2, As corrected on ]

February 14,1992," dated May 22,1992, U. S. Regulatory Commission.

2. Let'er, Wisconsin Electric Power Company (Wisconsin Electric), to NRC Document Control Desk, " Response to Generic Letter (GL) 87-02, Supplement 1 on SQUG Resolution of USl A-46, Point Beach Nuclear Plant Units 1 and 2," dated September 21, 1992. l 3 Letter, NRC, to Robert E. Link, Wisconsin Electric, " Evaluation of Point Beach Nuclear Plant 120-Day Response to Supplement No.1 to Generic Letter 87-02," dated ~

Abruary 22,1993.

4. Letter, Wisconsin Electric, to NRC Document Control Desk, " Generic Letter 87-02.-

Summary Report for Resolution of Unresolved Safoty issue A-46, Point Beach Nuclear  !

Plant, Units 1 and 2," dated June 30,1995.

5. Letter, NRC, to Neil Smith, SQUG, " Evaluation of Seismic Qualification Utility Group's i Responses to Generic issue included in NRC's Request for Additional Information," l dated December 2,1997. l p 6. Letter, Wisconsin Electd:, to NRC Document Control Desk, " Response to Request for l

, Additional Information...," dated September 30,1996. l h

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7. Letter, WisconsJn Electric, to NRC, 'Resoonse to Request for Additional Information...."

dated July 31.1997.

- 8. Letter, NRC, to Robert E. Unk, Wisconsin Electric, " Request for Additional Inforrnation...," dated May 23,1996.

9. Letter, NRC, to Robert E. Unk, Wisconsin Ebetric, " Request for Additional hbrmation...," dated May 10,1997.

'10. Telephone conference between Wisconsin Electric and NRC staff on May 8,1998. .

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