ML20236V489
| ML20236V489 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 07/30/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20236V484 | List: |
| References | |
| REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR GL-87-02, GL-87-2, NUDOCS 9808030274 | |
| Download: ML20236V489 (11) | |
Text
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&M fu g
k UNITED STATES g
j NUCLEAR REGULATORY COMMISSION e
i WASHINGTON, D.C. 20066 4001 5.;'...../
SAEEI" EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO RESPONSE TO GENERIC LETTER 87-02. SUPPLEMENT NO.1 OMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION. UNIT NO.1 DOCKET NO. 50-285
1.0 INTRODUCTION
On February 19,1987, the NRC issued Generic Letter (GL) 87-02, " Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors, Unresolved Safety issue (USI) A-46." In the GL, 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 (GIP) for Seismic Verification of Nuclear Plant Equipment," Revision 2.
l On May 22,1992, the NRC issued Supplement 1 to GL 87-02 including the staffs Supplemental Safety Evaluation Report No. 2 (SSER-2) (Reference 1), pursuant to the 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 staffs SSER-2, or (2) an attemative method for responding to GL 87-02. The supplement also required that those addressees committing to implement GIP-2 provide an implementation schedule as well as detalled information including the j
procedures and criteria used to generate the in-structure response spectra (IRS) to be used for USI A-46.
By letters dated September 21,1992 (Reference 2) and February 11,1993 (Reference 3)
Omaha Public Power District (OPPD), the licensee, provided its response to Supplement 1 to l
GL 87-02 for the Fort Calhoun Station (FCS). In these letters, OPPD committed to follow the l
SQUG commitments set forth in GIP-2, including the clarifications, interpretations, and excep9ons identified in SSER-2. The staff issued its evaluations of the licensee's responses by l
letters dated October 18,1993 (Reference 4) and November 2,1993 (Reference 5).
l By letter dated September 28,1995 (Reference 8), OPPD submitted a summary report l
containing the results of the USl A-46 program implementation at the FCS. By letters dated August 23,1996 (Reference 11) and August 4,1997 (Reference 12), OPPD provided 9808030274 980730 PDR ADOCK 05000285 P
. supplemental information and c!arification in response to the staffs requests for additional information (RAls), dated June 21,1996 (Reference 9) and June 5,1997 (Reference 10),
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respectively.
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This report provides the staffs evaluation of the licensee's USl A 46 implementation program based on the stars 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 l
The staffe aview of USl A-46 summary reports for FCS (Reference 8) was performed in accordance with the USl 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 which did not readily pass GIP-2 screening and evaluation criteria. The summary report provides the evaluation of seismic adequacy of tanks and heat exchangers, cable and conduit raceways, relays, and outlier identification and resolution including proposed schedules.
I 2.1 Seismic Demand Determination i
i By letter dated December 2,1988, OPPD submitted the document "Altemate Seismic Criteria l
and Methodologies (ASCM) for the Fort Calhoun Station" to the NRC (Reference 6). This l
document proposed attemate seismic criteria and methodologies for design and analysis of
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structures, systems, and components which differed from, or did not exist in, the criteria provided in the FCS Updated Safety Analysis Report (USAR) Appendix F, Classification of Structures and Equipment and Seismic Criteria. This document was intended to provide an alternate ddgn basis for future new designs, modifications, and reanalyses of piping and pipe supports, electrical raceways, heating-ventilation-air-conditioning (HVAC) systems and components, and associated anchor bolts. Based on the staffs review of the methodology, with the assistance of Brookhaven National Laboratory, NRC issued a Safety Evaluation Report on the acceptance of the ASCM on April 16,1993 (Reference 7).
In a letter dated October 18,1993 (Reference 4), the staff approved the use of these refined in-
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Structure Response Spectra (IRS) as conservative design for all areas in the plant for resolving USI A-46. The licensee provided, in the submittal, the figures for typical IRS included in the ASCM. Since the USl A-46 program implementation was concurrently performed with the Individual Plant Examination for Extemal Events (IPEEE), the licensee used a scaled version of the IRS generated for the ASCM as described below for the USI A-46 program.
The peak-broadened IRS generated as part of the ASCM, were scaled to IPEEE motion (0.3g NUREG/CR-0098 spectral shape). For this scaling, the dominant frequency of the particular f
building model (auxiliary building / containment building model, or intake structure model) and j
s, oil case (upper bound or lower bound) was determined first. The scale factor was then 1
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established on the basis of the ratio of the 7 percent of critical damping 0.3g NUREG/CR-0098 9
' median peak spectral acceleration for soil site (0.57g) to the average ASCM response input time-history spectral acceleration, at 7 percent of critical damping, within plus and minus 10 percent of the predominant building model frequency determined above.
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l The scale factors established as indicated above for the upper bound and lower bound soil i
cases were cor>servatively enveloped. This enveloped scale factor was used to multiply the 5 percent of the critical damping IRS generated as part of the ASCM to obtain the scaled 5 percent of critical damping IRS for use in the IPEEE program. Additionally, to conservatively account for greater soil property variations, these scaled spectra were broadened by another plus or minus 10 porcent in frequency. Finally for the USl A46 program, these scaled and l
broadened IRS was scaled down by the ratio of the SSE peak ground acceleration (0.17g) to f
the IPEEE peak ground acceleration (0.30g).
The results of the above scaling procedure are summarized in a table in the Summary Report l
(Reference 8) in terms of factors used to scale the ASCM spectra to obtain the IRS for use in the USl A46 program. These scaled IRS were used in the USI A46 program as " median-centered" IRS. On the basis of the procedure described above, the licensee concluded that the A46 spectra were conservatively generated (Reference 11). On the basis of its review of the information provided, the staff concurs with the licensee's conclusion.
2.2 Seismic Evaluation Personnel i
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 the evaluation of relay chatter and ! identification of electrical SSEL components.
The staff found that the seismic capability engineers who were members of the SRT and the system engineers, possessed considerable experienca in design and analysis and met the qualification and experience requirements of GlP 2 ano, therefore, are acceptable.
2.3 Safe Shutdown Path in its submittal of September 28,1995 (Reference 8), the licensee identified the following plant safety functions: reactivity control; inventory control; and decay heat removal. Paths 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 a safe shutdown earthquake (SSE). Attachment A, Figures 1 through 4 of the licensee's " Safe Shutdown Equipment List (SSEL) Report" provides these shutdown success paths. A list of the equipment necessary for the safe shutdown paths is included in Attachment B of the licensee's submittal.
i The shutdown margin will be ensured by insertion of control element assemblies and by boron injection via the chemical and volume control system (CVCS). The boron injection flow path is from the boric acid storage tanks (BAST), through the reactor coolant system (RCS) loops 1 A L
and 2A cold leg injection points into the RCS. Pumping is provided by the charging pumps.
Reactor coolant inventory makeup is also achieved via the CVCS. The initial source of borated
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4 water for this function is from the BASTS. Upon depletion of the BASTS, the safety injection and refueling water storage tank (SIRWT)is utilized. The remainder of the injection path is the same as that used for ensuring the shutdown margin. Reactor decay heat removal is accomplished by secondary heat removal. This operation consists of feeding water from the emergency feedwater storage tank (EFWST) to the steam generators via the auxiliary feedwater pumps and allowing steaming (boil off) of the steam generators through the steam generator main steam safety valves. However, since the amount of water in the EFWST is only sufficient for eight hours of decay heat removal, makeup to the EFWST will be provided by the raw water system.
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 /> following a seismic event is acceptable.
2.4 Seismic Screenino Verification and Walkdown of Mechanical and Electrical Eauloment 2.4.1 Eauioment Seismic Canacity Comoared to Seismic Demand The licensee's comparison of seismic capacity to seismic demand was described in its response to a staff question and is provided in Attachment 2 of Reference 11. The IRS for the auxiliary building, containment building and its intemal structures at elevations within 40 feet above the effective grade (1004 ft.) is shown to be enveloped by 1.5 times the SQUG Bounding Spectrum, for frequencies greater than 8Hz. In general, the licensee used Method A of GlP-2 to compare the equipment seismic capacity to seismic demand. However, the licensee indicated that both Method A and Method B, were applicable, since the licensing-basis floor response spectra generated on the basis of the SSE gTund response spectra did not exceed 1.5 times the SQUG Bounding Spectrum at any elevation within 40 feet above the effective grade level. The FCS structures are supported on soil-pile foundation system through foundation mats. According to the licensee, the foundation input motions which correspond to the free-field motions were applied at the foundation elevation in the free field. The staff verified this to be the case. The staff found the licensee's assessment of equipment seismic demand reasonable and acceptable.
2.4.2 Assessment of Equioment Caveats
" Caveats" are defined as the set of inclusion and exclusion rules which represent specific characteristics and features particularly important for seismic adequacy of a particular class of l
equipment. The licensee identified specific cases in equipments where the intents of the i
caveats are considered to be met, rather than the specific wording of the caveat rule. There were seven cases involving 13 fluid operated valves which were accepted based on meeting the intent of the caveat. The staff did not identify any discrepancy with the licensee's assessment of the equipment caveats.
2.4.3 Equipment Anchorages The equipment anchorage evaluation was provided in response to the staff's supplemental request for additional information and is contained in Reference 12. The staff reviewed the
- licensee's anchorage evaluation and found that the licensee did not follow GlP-2 provisions for evaluation of the capacity of some anchors. The anchFages involved were cast-in-place J-bolts. As a result of staff comments, the licensee revised the calculations on J-bolt pull out capacity for two cases in accordance with the provisions of GIP-2 and found that there was some reduction in the pullout capacity in both cases but not to the extent to affect the conclusion on the adequacy of the anchorages. The staff also had a concem with the evaluation of a pedestal where both anchor bolts (as rebars) and concrete was accounted for to resist shear loads. The staff's position was that, either the rebar or the concrete, not both, should have been considered to resist shear. The licensee revised the calculation and found the design to be adequate in spite of the reduction in shear capacity of the anchor bolts and the exclusion of concrete shear capacity. By reducing the J bolt tension and shear capacity, the licensee checked for the combined tension and shear interaction criterion and found it to be i
satisfactory.
The revision to the anchorage calculation demonstrated the adequacy of equipment anchorages verified during the USl A-46 program implementation. The staff, therefore, finds the licensee's action regarding equipment anchorages to be acceptable.
2.4.4 Seismic Soatial Interaction Some aspect of the USI A-46 program focuses on review of the potentialinteraction of non-seismic structural systems or components with the equipment in the safe shut down path.
In Table 7 of Section 8.0 of Reference 8, equipment accepted on the basis of existing documentation is listed. According to this table, there are a number of equipment items which may potentially be affected by adjacent masonry block walls as a result of a seismic event, in order to assure that the function of the safety-related equipment located adjacent to a masonry wall would not be jeopardized by the collapse of the masonry wall during an earthquake, the licensee provided a sample analysis of such a masonry wall (identified as block wall No. 9) for the potential seismic event and concluded that the wall was adequate for the design basis earthquake. The staff reviewed the analysis and identified an error that was subsequently corrected by the licensee. The original conclusion, however, was not affected by the change. The staff, therefore, concurs with the conclusion that the wall can safely resist the I
design basis earthquake. The licensee indicated that there were a number of block walls which l
had been seismically qualified by similar calculations.
The licensee identified 25 items of equipment which were not properly installed or anchored and L
could potentially impair their own function or the function of other adjacent equipment as a result of impact during a seismic event. The licensee identified some of these outliers as resolved and provided a schedule for others to be resolved at a later date as summarized in Table 8 of the Summary Report (Reference 8). The schedule for resolution as indicated in the table ranged from April 1996 to December 1996. On July 8,1998, the licensee informed the staff (Reference 14) that it had completed the required physical modifications as scheduled in the table. Therefore, all outliers pertaining to the above equipment have been satisfactorily resolved. The staff finds that the licensee's resolution of seismic spatialinteraction aspect of the USI A-46 to be reasonable and acceptable.
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2.5 Tanks and Heat Exchanoers in Table 8 of Section 9.2 of Reference 8, the tank and heat exchanger outliers are listed. Of
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the 36 tanks and heat exchangers which were evaluated as part of the USI A-46 program, the licensee identified 24 as outliers requiring resolution. Two of the 24 had sight glass problems that the licensee planned to resolve by replacing the breakable sight glasses. Out of 22 remaining tank outliers, three were msolved by performing detailed analysis. Eight horizontal tanks were classified as outliers because they were not adequately connected to their respective supports. Each tank is 15 inches in radius,72 inches long, and weighs less than 1000 pounds. The licensee planned to resolve these outliers by spot welding or strapping each tank to one of its two supports so that each tank would be held in position during an earthquake i
while allowing it to expand in the other direction to accommodate thermal loads. The resolution and schedule for the proposed modification of these 8 tanks are discussed in Table 8 of l-Reference 8. In response to a staff's concem (Reference 11, response to Question 4) regarding the potential buckling of these tanks during a postulated SSE, the licensee provided reasonable argument that due to the small size of each of these tanks, the resulting axial force in the tank wall due to a horizontal earthquake motion is too insignificant to cause buckling. Out l
of the eleven remaining tank outliers, one tank (WD-21) was resolved by modification and the q
i remaining ten tank outliers were resolved by detailed analyses. The licensee provided sample calculations for the support systems of these tanks including their anchorage. The staff reviewed the evaluation procedures and found them to be acceptable, with the exception of those relating to the anchorages, as indicated in Section 2.4.3 on equipment anchorages above. The licensee also submitted the existing design basis calculation for a buried diesel fuel oil tank which is 23 feet long,12 feet in diameter, with 5/16-inch thick walls and in which the tank top is 2.5 feet below grade. On the basis of the results of this calculation which was reviewed originally under the licensee's QA program, the licensee determined the tank to be seismically adequate. The staff performed an independent evaluation and found the licensee's conclusion to be reasonable. On the basis of the review of the information provided, the staff concludes that the tank and heat exchanger outliers have been satisfactorily resolved in response to the staff's question (No. 5, Reference 11) as to whether the method described in Appendix H of the EPRI Report NP-6041-SL was used in the tank analysis, the licensee responded that it was not used in the resolution of any of the US! A-46 tank.
2.6 Cable and Conduit Raceways Section 5.2 of the Summary Report provided a description of the walkdown of the cable and conduit raceways (CCRs). The walkdown was performed by the licensee's SRT in accordance with Section 8.2 of GlP-2. The walkdown covered 26 areas: one in the intake structure; one for raceways between the auxiliary building and the intake structure; 18 in the auxiliary building; and 6 in the containment building. During the walkdown,15 " representative, worst case" raceway supports were selected for Limited Analytical Review (LAR) in accordance with the selection criteria contained in Section 8.2.4 of GIP-2. T. he licensee summarized the results of its analyses of the 15 LARs in a table which indicated the loading involved in each installation and whether or not the acceptance criterion limit of 1.0 for the so-called " interaction value" was met. For cases greater than 1.0, the resolution was made by the SRT using engineering I
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judgment. The CCR review resulted in 8 outliers. They consisted of loose conduit clamps; a missing clamp; a broken conduit hanger; a missing hanger rod; an inadequate conduit support; l
support span exceeding 10 feet; and corroded raceway supports.
The licensee has stated that all outliers pertaining to cables and conduits would be resolved and indicated that some of them have already been resolved. For others, a schedule for resolution has been provided, as indicated in Table 3 and Table 8 of Reference 8. The staff finds that the licensee's evaluation of cables and conduits has reasonably met the provisions of GIP-2 and the staffs SSER No. 2 and, therefore, is acceptable.
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2.7 Essential Relavs j
The licensee prepared a comprehensive list of the contact pairs on relays and/or other devices I
associated with the SSEL equipment and identified it as the Associated Relay List (ARL). The j
ARL was' examined to verify that it did nct contain any mechanical or solid state devices which are considered to be inherently rugged. The ARL was modified to eliminate those devices that were determined to be nonessential by performing light functional screening involving circuit analysis. A detailed circuit analysis (DCA) was performed using the safe shutdown equipment j
state to determine if chatter of certain relay contacts in the control path is functionally -
acceptable. Based on the normal, desired, and failed states of the SSEL equipment being controlled by a given circuit, the specific function of each device within that circuit was examined if it was determined that for a given contact pair, chatter was acceptable, that contact pair was eliminated from further evaluation. Thus, an essential relay list (ERL) was developed, which contained relays and other devices with contacts that are essential to the control of required safe shutdown equipment. The seismic capacity of essential relays was
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based on available test data from Generic Equipment Ruggedness Spectra (GERS),
earthquake expcnence data, and specific seismic test data. The seismic demand was based on ISRS modified by appropriate safety factor and in-cabinet amplification factor. A relay was seismically screened out if its GERS capacity equaled or exceeded the demand in low and high frequency ranges, if a relay did not pass the screening, refined seismic demands were determined using GENRS computer program with medium centered or conservative design ISRS. Relays for which the seismic capacity was less than the demand, were identified as outfiers and planned for resolution during the 1998 outage. The staff concludes that the j
licensee's methodology for evaluation of essential relays is acceptable.
j 2.8 Human Factors Ascact l
The staffs review focused on verifying that the licensee had used one or more of GIP-2 methods for conducting the operations department 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 which outlined the use of the " desk-top" evaluation method I.
by a team of technical representatives from Operations, Operations Training, Systems Engineering, Nuclear Engineering, Electrical /l&C Engineering, and Mechanical Engineering.
The team verified that existing normal, abnormal and 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 licensee had considered its enerator training programs and verified that its training was sufficient to ensure that those actions specified in the procedures could be accomplished by the operating crews. In addition, the staff requested verification that the licensee had adequately evaluated potential c.hallenges 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 hostile environment. The licensee provided information regarding its seismic evaluations and " desk-top" evaluations to substantiate that operators' actions could be accomplished in a time frame required to mitigate the transient. Locations of equipment which needed to be manipulated were verified to be in seismically designed buildings with ingress / egress pathways accessible from the control room. Lighting Isels and ambient environmental conditions were analyzed and determined to be adequate to ensure habitability of the areas during transient response. The licensee has provided the staff with sufficient information to demonstrate conformance with the NRC-approved review methodology outlined in SQUG GIP-2 and the staff's SSER No. 2 and is, therefore, acceptable.
2.9 Outlier Identification and ResolutiSDA The licensee classified items of identified safe shutdown equipment as outliers if the screening guidelines of GIP-2 were not met. If an !*em cf equipment was identified as an outlier during the screening evaluation, the reason for failing to satisfy the screening guidelines was documented in an Outlier Seismic Verification Sheet. The following is a summary of the outliers and their status of resolution for various equipment and installations inc'uded in USI A 46 program review:
(a) Mechanical and Electrical Equipment Outliers Of the 368 mechanical and electrical equipment items examined and evaluated by walkdowns,55 were identified as outliers. Of the 55 outliers,9 items involved some kind of interaction concem and 8 involved some type of anchorage concem. The 55 outliers are grouped and tabulated as 25 category items (Table 8, Reference 8). About half of these items are identified as resolved and for the others a schedule of resolution was provided. In a letter dated April 16,1998 (Reference 13), the licensee informed the staff that it had made the necessary modifications as scheduled. Therefore, all the l
mechanical and electrical outliers have been resolved.
(b) Tanks and Heat Exchangers Outliers Twenty-four (24) tank and heat exchanger outliers were identified and their resolution is discussed in Section 2.5 above. One tank identified as an outlier was resolved by modification as scheduled (Reference 8, Table 8 ltem 22).
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(c) Cable and Conduit Raceway Outliers Eight (8) outliers were identified. The status and schedule for their resolution were provided in Table 8 of Reference 8. The licensee informed the staff (Reference 13) that it had made the necessary modifications as scheduled and all outliers pertaining to cable and conduit raceways are resolved.
(d) Relay Outliers Eighteen (18) relays were identified as outliers and their resolution schedule was provided. Twelve relays have been replaced and the remaining six outliers are scheduled for replacement during the 1998 outage (Reference 13).
Overall, the licensee has provided the recommended resolution, the status and a tentative schedule for each of the outliers in the Seismic Evaluation Report. The staff has determined that the licensee's identification and resolution of outliers were consistent with the guidelines of GIP-2 and the staffs SSER No. 2. The licensee informed the staff (Reference 13) that all outliers except six relay outliers have been resolved. These six relay outliers are scheduled for replacement during the 1998 outage. The licensee subsequently informed the staff (Reference
- 14) that the remaining six relay outliers had been resolved based on completed modifications.
i 3.0 Summarv of Staff Findina The staffs review of the licensee's USI A-46 implementation program, as provided for each area discussed above, did not find any significant or programmatic deviation from GlP-2 regarding the walkdown and the seismic adequacy evaluations at Fort Calhoun Station.
4.0 CONCLUSION
The licensee's USI A-46 program at Fort Calhoun was established in response to Supplement 1 to GL 87-02 through a 10 CFR 50.54(f) letter. The licensee conducted the USI A-46 Implementation in accordance with GIP-2 and the staffs SSER No. 2. The licensee's submittal on the USI A-46 implementation indicated that 368 eqcipment items,36 tanks and heat exchangers, and cable and conduit raceways in 26 plant areas were evaluated. Out of these, 53 equipment items and 24 tanks and heat exchangers were identifed as outliers. All these outliers have been resolved. Eighteen relays were identified as outliers. The licensee informed the staff (Reference 13) that twelve relay outliers had been replaced and the remaining six were replaced during the 1998 refueling outage (Reference 14). The licensee's implementation report did not identify any instance where the operability of a particular system or component was questionable. As described in Section 3.0, the staffs review did not identify any areas I
where the licensee's program deviated from GlP-2 and the staffs SSER No. 2 on SQUG/ GIP-2 issued in 1992.
The staff concludes that the licensee's USI A-46 implementation program has, in general, met the purpose and intent of the criteria in GIP-2 and the staffs SSER No. 2 fcr the resolution of USl A-46. The staff has determined that the licensee's already completed actions will result in safety enhancements, in certain aspects, that are beyond the original licensing basis. As a m
, result, the licensee's actions provide sufficient basis to close the USI A-46 review at the facility.
The staff also concludes that the licensee's implementation program to resolve USl A-46 at the facility has adequately addressed the purpose of the 10 CFR 50.54(f) request. Licensee activities related to the USl A-46 implementation may be subject to NRC inspection.
Regarding future use of GlP-2 in licensing activities, the licensee may revise its licensing basis in accordance with the guidance in Section 1.2.3 of the staff's SSER No. 2 on SQUG/ GIP-2, and the staff's letter to SQUG's Chairman, Mr. Neil Smith on June 19,1998. Where plants have specific commitments in the licensing basis with respect to seismic riualification, 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. An overall conclusion that no unreviewed safety question (USQ) is involved is acceptable so long as 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 USQ is involved, incorporation of the GIP-2 methodology into the licensing basis would require the licensee to seek an amendment under the provisions of 10 CFR 50.90.
5.0 REFERENCES
1.
NRC'S letter to SQUG Members," Supplement No.1 to Generic Letter 87-02 transmitting Supplemental Safety Evaluation Report No. 2 (SSER No.2) on SQUG Generic Implementation Procedure, Revision 2," dated May 22,1992, as corrected on February 14,1992 (GIP-2).
2.
Letter, W. G. Gates, OPPD, to NRC Document Control Desk, (LIC-92-301R) dated September 21,1992.
3.
Letter, W. G. Gates, OPPD, to NRC Document Control Desk, (LIC-92-301R) dated February 11,1993.
4.
Letter, NRC to OPPD, " Evaluation of Cisrification of 120-day Responses to Supplement No.1 to Generic Letter 87-02 for Fort Calhoun Station," dated October 18,1883.
5.
Letter, NRC to OPPD, " Evaluation of Omaha Public Power District's Clarification of 120-day response to Supplement 1 to Gener'.: ' etter 87-02 for Fort Calhoun," dated November 2,1993.
6.
Letter, K. J. Morris, OPPD, to NRC Document Control Desk, (LIC-88-506) dated December 2,1988.
7.
Letter (with attachment), S. Bloom, NRC, to Terry L. Patterson, OPPD, dated April 16, 1993.
8.
Letter, OPPD (T. L. Patterson), to NRC (Document Control Desk)" Fort Calhoun Station Seismic Evaluation Report" summarizing results of USI A-46 review, in response to GL 87-02 dated September 28,1995.
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' 9.
Letter, NRC (L. R. Wharton) to OPPD (T. L. Patterson)" Request for Additional Information on the Resolution of USI A46," Fort Calhoun Station dated June 21,1996.
10.
Letter, L. R. Wharton, NRC, to S. K. Gambhir, OPPD, "Supp5 mental Request for Additional information on the Resolution of USI A46," Fort valhoun Station dated June 5, 1997.
11.
Letter, T. L. Patterson, OPPD, to NRC Document Control Desk, " Response to Request for Additional Information on the Resolution of USl A46," Fort Calhoun Station dated August 23,1996.
12.
Letter, S. K. Gambhlr, OPPD, to NRC Document Control Desk, " Response to Supplemental Request for Additional Information on the Resolution of USI A46," Fort Calhoun Station dated August 4,1997.
13.
Letter, S. K. Gambhir, OPPD, to NRC Document Control Desk, " Status of Resolution of Unresolved Safety issue (USI) A46 Generic implementation Procedure (GIP-2) Outliers."
dated April 16,1998.
14.
Letter, S. K. Gambhir, OPPD, to NRC Document Control Desk, " Resolution of Unresolved Safety issue (USI) A46 Generic Implementation Procedure (GIP-2) Outliers,"
dated July 8,1998.
Principal Contributors:
C. P. Tan P. Patnalk Date of issuance: July 30,1998 l
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