ML20212J050

Safety Evaluation Re Licensee Implementation Program to Resolve USI A-46 at Plant,Per GL 87-02,Suppl 1

ML20212J050
Person / Time
Site:	Quad Cities
Issue date:	09/21/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20212J047	List: ML20212J045 ML20212J050
References
REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR GL-87-02, NUDOCS 9910050008
Download: ML20212J050 (19)

Text

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t NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20066-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RESPONSE TO GENERIC LETTER 87-02. SUPPL EMENT NO.1 COMMONWEALTH EDISON COMPANY N

A.N.Q MIDAMERICAN ENERGY COMPANY QUAD CITIES NUCLEAR POWER STATION. UNITS 1 AND 2 DOCKET NOS. 50-254 AND 50-265

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1.0 BACKGROUND

in December 1980, the NRC designated " Seismic Qualification of Equipment in Operating Plants" as Unresolved Safety issue (USI) A-46. The safety issue of concern was that -

equipment in nuclear plants for which construction permit applications had been docketed before about 1972 had not been reviewed according to the 1980-81 licensing criteria for the seismic qualification of equipment, such as Regulatory Guide (RG) 1.100 (Reference 1),

Institute of Electrical and Electronics Engineers (IEEE) Standard 344-1975 (Reference 2), and i Section 3.10 of the Standard Review Plan (SRP) (NUREG- 0800, July 1981) (Reference 3). To address USI A-46, affected utilities formed the Seismic Qualification Utility Group (SQUG) in 1982.

The NRC staff issued Generic Letter (GL) 87-02 in February 1987 (Reference 4) to provide guidance for the resolution to USl A-46. It concluded that the seismic adequacy of certain equipment in operating nuclear power plants should be reviewed against seismic criteria not in use when these plants were being constructed. In 1987, SQUG, representing its member utilities, committed to develop a Generic Implementation Procedure (GIP) for implementing the

,. ' resolution of USl A-46. SQUG requested a deferment of the 60-day response period for GL B7-02 until after the NRC issued its final safety evaluation report (SER) on the final version of the GlP.

. On May 22,1992, the staff issued Supplement No.1 to GL 87-02 which transmitted its final SER (SSER No. 2 (Reference 5)) on the then final version of the GlP (GIP Revision 2, as corrected on February 14,1992, or simply GIP-2 (Reference 6)). In the supplement to GL 87-02, the staff requested those USl A-46 licensees, who are members of SQUG, to either j provide a commitmen't to use both the SQUG commitments and the implementation guidance 9910050008 990921 DR ADOCK O 24 ENCLOSURE L

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r described in GIP-2, as supplemented by the staff's SSER No. 2, or provide an alternative

, method for responding to GL 87-02. In a letter dated September 21,1992 (Reference 7),

Commonwealth Edison Company (Comed), the licensee for Quad Cities Nuclear Power

' Station,~ Units 1 and 2, and a member of SQUG, committed to the implementation of GIP-2 for resolving USl A-46 at the Quad Cities plant.' The NRC subsequently approved the licensee's approach and schedule in a letter dated November 20,1992 (Reference 8).

By letter dated June 28,1996 (Reference 9), Comed submitted a report summarizing the results ofits USl A-46 implementation program,- The staff reviewed the report and issued a request for additional information (RAl) on August 19,1997 (Reference 10). The licensee subsequently submitted its response to the RAls in letters dated October 24,1997 (Reference

12) and November 25,1997 (Reference 13). The staff reviewed the licensee's responses and determined that further information was required from the licensee in order for the staff to complete its review. Additional RAl's were issued to Comed on March 24,1998 (Reference

' 14) and April 29,1998 (Reference 11), to which Comed responded on July 31,1998

'(Reference 15). The licensee subsequently provided additional information on the development of the realistic median-centered spectra in its submittal of March 19,1999 (Reference 16).

This report provides the staff's evaluation of the licensee's USl A-46 implementation program based on the staff's review of the summary report, supplementa!information and clarification provided by the licensee in response to the staff's RAls.

2.0 QlSCUSSION AND EVALUATION The staff's review of the Quad Cities USI A-46 summary report (Reference 9) consiste of a screening-level review of specific sections of the licensee's program, with emphasis pin od on identification and resolution of outliers, i.e., equipment items which did not readily pass GIP-2 screening and evsduation criteria. The report identifies a safe shutdown equipment list (SSEL) and contains the screening verification and walkdown of mechanical and electrical equipment.

The report also contains relay evaluations and the evaluation of seismic adequacy for tanks and heat exchangers, cable and conduit raceways, and the identification and resolution of outliers, including the proposed resolution schedules.

2.1 Seismic Demand Determination (Ground Soet,tra and in-structure Response Spectra)

The Quad Cities safe shutdown earthquake (SSE) is defined by Housner-like ground response spectra (GRS) with a zero period ground acceleration of 0.24g. Comed characterized these spectra as the design response spectra (DRS) for the plant. Comed used the normalized  !

North-South component of the 1940 El Centro earthquake as the input time-history for 19enerating the in-structure response spectra (IRS). Based on the information provided in Comed letters of September 21,1992 (Reference 7) and January 15,1993 (Reference 17),

regarding the development of synthetic time-histories, modeling parameters, and assessment l

- of the selected IRS,' the staff had concluded that the in-structure spectra developed by Comed's procedure was acceptaHe as " conservative design," for the purpose of verifying the adequacy of equipment (Refere,nce 18). To resolve some of the equipment outliers, the licensee developed realisticMy median-centered (RMC) spectra at various floor levels

(, Reference 16). The licersee utilized more realistic criteria (e.g., the conservatism in the input 1

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- time-history was removed, and more realistic soil modeling and higher damping values were used) for developing these spectra. A comparison of the RMC spectra with the " conservative j

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• spectra indicates that the amplitudes of the RMC spectral peaks are about 80 percent of those of the conservative design spectra peaks, with a little change in the peak frequencies.

The staff considers the results reasonable and finds the licensee's approach for determining the seismic demand consistent with the provisions of GlP-2 and, therefore, acceptable for use in USl A-46 Program.

2.2 Seismic Evaluation Personnel The screening verification, walkdown, and outlier identification was performed by a seismic review team (SRT) comprising seismic capability engineers (SCE) as defined in GIP-2. ' GIP-2 describes the responsibilities and qualifications of the individuals who implement this generic procedure. For a complete resolution of the USl A-46 issue, the seismic evaluation personnel should include individuals with sufficient expertise to identify safe shutdown equipment, perform the plant walkdown and verify the seismic adequacy of equipment and cable / conduit raceway systems, and to perform the relay screening and evaluation. This involves a number of plant and engineering disciplines including structural, mechanical, electrical, system, earthquake, and plant operations. Based on the information provided in Appendix C to the Seismic Evaluation Report and in Reference 12, the staff concludes that the qualifications of the individuals responsible for implementing the resolution of the USl A-46, including the third party reviewers, '

' meet the criteria of GIP-2 and the staff's SSER No. 2 and is, therefore, acceptable.

2.3 Safe Shutdown Path I

. GL 87-02 specifies that the licensees shcold 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, the I

~ licensee addressed the following plant safety functions in the seismic evaluation report (Reference 9): reactor reactivity control, pressure control, inventory control, and decay heat removal. A primary and an attemate safe shutdown success path with their support systems  ;

- and 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 A provides the SSEL.

The reactor decay heat removal function is accomplished by relieving steam from the reactor via the Electromatic relief valves (ERV) for Unit 1 and Target Rock power operated relief valves for Unit 2.into the suppression pool. The automatic depressurization system (ADS) depressurizes the reactor vessel so that the low pressure coolant injection (LPCI) mode of the residual heat removal (RHR) system, which takes suction from the suppression pool, can be

' initiated for reactor coolant inventory control. The decay heat removal is achieved by placing the RHR system in the suppression pool cooling (SPC) mode of operation. During the SPC mode'of RHR, the RHR system tWs suction from and discharges to the suppression pool via the RHR heat exchangers. Tiw RhR service water system (RHRSW) provides the capability to transfer the decay heat from the RHR system to the ultimate heat sink (Crib House Bay).

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The plant Operations depadment reviewed the safe shutdown success paths and concluded that the plant operating procedures and operator training were adequate to establish and l maintain the plant in a safe shutdown condition using the equipment identified in Appendix A.

. The staff concludes that the approach to schieve and maintain a safe 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 acooptable.

2.4 Seismic Screenin'a Verification and Walkdown of Mechanical and Electrical Eauioment The staffs evaluation focused primarily on the licensee's identification and resolution of

. equipment outliers, i.e., equipment items which do not comply with all of the screening guidelines provided in GlP-2. GIP-2 screening guidelines are intended to be used as a generic basis for evaluating the seismic adequacy of equipment. ' If an item of equipment fails to pass these generic screens however, it may still be shown to be adequate by additional evaluations.

2.4.1 Eauioment Seismic Canacity Compared to Seismic Demand The first screening guideline is the comparison of seismic capacity and seismic demand for the 7 equipment involved. The licensee determined the seismic capacity of Quad Cities safe

, shutdown equipment using:

(1) . Earthquake experience data with capacity defined by the SQUG Bounding Spectrum (BS), or 1.5 times BS (Reference Spectrum), depending on the demand spectrum used.

(2) Generic seismic test data which have been compiled into generic equipment ruggedness spectra (GERS).

(3) Equipment specific seismic qualification data, or data trom similar equipment.

1 Table 4-1 of GlP-2 specifies two methods for comparing equipment seismic capacity to the seismic demand on the equipment resulting from the postulated SSE. Method A is limited to equipment located within 40 feet of the effective grade and having a fundamental frequency of vibration greater than 8 Hz. In Method A, the capacity of the equipment is expressed in terms of BS and GERS and the demand on the equipment is expressed in terms of the plant GRS and its multiplier, respectively. Method B can be used for all conditions. In Method B, the capacity is expressed in terms of 1.5 x BS and GERS and the demand in terms of appropriate IRS. Equipment with seismic demand exceeding its capacity is declared an outlier.

In Appendix B of the final summary report (Reference 9), the licensee has provided the SSE-IRS at various elevations in the East-West and Nodh-South directions. The staff review of the l lRS plots indicated that at a number of locations within 40 feet of the effective grade, the amplifications were greater than 1.5 times the GRS at frequencies higher than 8 Hz. Method A in Table 4-1 of GlP-2 allows the use of BS (as the demand spectrum) for such conditions with a note in Section'4.2.3 that states: "The restrictions and limitations on the use of the around response spectrum for comparison to the Bounding Spectrum and the GERS is based on the conditions that the amplification factor between the free-field response spectra and the L

in-structure response spectra will not be more than 1.5, and that natural frequency of the equipment is not in the high energy range.... "

For most of the equ'pment located within 40 feet of the effective grade and having fundamental frequencies greater than 8 Hz, the amplification factor of the RMC spectra over the GRS is about 1.5 at the appropriate frequencies, with the following exception. The RMC peak spectral acceleration for the reactor building in the East West direction, at 28-feet above the effective grade, is about 2.5 times the corresponding GRS acceleration. However, considering (1) the conservatism contained in the generation of the RMC spectra, such as the peak broadening of spectral peaks; (2) that the exceedance is over a short frequency range; and (3) that the building foundation is built into the foundation rock, the staff finds the use of Method A of GIP-2 justifiable for the verification of the seismic adequacy of the equipment. The staff also finds the use of the RMC spectra as the demand spectra for outlier evaluations acceptable.

Based on the above, the staff finds the licensee's approach for the evaluation of equipment seismic capacity against seismic demand acceptable as it meets the provisionr of GIP-2.

< 2.4.2 Assessment of Ecutoment Caveats i

' As a second screening guideline, the licensee venfied the seismic adequacy of an item of mechanical or electrical equipment by confirming that (1) the equipment characteristics are generally similar to the earthquake experience equipment class or the generic seismic testing equipment class, and (2) the equipment meets the intent of the specific caveats for the equipment class. This review is only necessary when the BS or the GERS is used to represent the seismic capacity of an item of equipment. If equipment specific seismic qualification data is used instead, then only the specific restrictions applicable to that equipment-specific qualification data need be applied.

The " caveats" are defined as a set of inclusion and exclusion rules that are established to represent specific characteristics and features particularly important for seismic adequacy of a particular class of equipment. Appendix B of GIP-2 contains a summary of the caveats for the earthquake experience equipment classes and for the generic seismic testing equipment class.

The licensee stated in Reference 9 that the SRT which consists of at least two SCEs walked down all accessible SSEL equipment items to look for all applicable caveats and documented them in the seismic evaluation walkdown sheets (SEWS).

Another aspect of verifying the seismic adequacy of equipment included within the scope of this procedure is explained by the " rule of the box." For the equipment included in either the earthquake or testing equipment class, all of the components mounted on (or inside) this equipment are considered to be part of that equipment and do not have to be evaluated separately. However, the walkdown engineers did look for suspicious details or uncommon situations which could make the equipment item vulnerable.

When evaluating an item of equipment, the SCEs often used engineering judgment to determine whether the specific seismic concern addressed by the caveat was met. They evaluated each item of equipment to determine whether it meets the specific wording of the applicable caveats or their intent.' If they judged an item of equipment to meet the intent, but 1

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. not the spehific wording of the caveats, that item was considered to have met the caveat.

s During the walkdowns and seismic adequacy evaluations performed at Quad Cities, the SRT identified some such instances for which the specific wording of certain caveats was not met.

Comed summarized these in Table 5-1 of Reference 9. . The staff reviewed the information

- provided in Table 5-1 and concluded that the SRT's judgement and the licensee's additional evaluations and measures to meet the intent of the GlP-2 caveats acceptable.

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2.4.3 Eauioment' Anchorace.

The licensee states (Reference 9) that it verified the anchorage adequacy with an approach incorporating three elements: (1) comparison of the anchorage capacity with the demand,

'(2) evaluation of the anchorage to verify that it is free of gross installation defects, ord

. (3) evaluation of the equipment anchorage load path to verify that there is adequaie stiffness

- and strength. The screening methodology for verifying the seismic adequacy of equipment anchorage utilized a combination of (1) inspection, (2) analysis, and (3) engineering judgement.

. Analyses consisted of comparing the anchorage capacity to the demand generated by the postulated seismic event. The licensee performed these analyses using the guidelines in Section 4 and Appendix C of GIP-2. They accepted small equipment, weighing 50 lbs. or less, by judgement and a " tug test." The tug test consisted of pulling on the device (e.g., a wall-mounted transmitter) with a force exceeding three times the seismic demand calculated at the equipment location.

Comed visually inspected all accessible anchorages. The licensee checked all anchorages

' against the fourteen (14) attributes listed in GIP-2, which included: type of anchorage, size and location of anchorages, embedment length, edge distance, and equipment base stiffness.

For expansion snchors, the licensee performed a tightness check to detect gross installation defects that included oversized holes in the concrete, total lack of preload, and missing plugs.

. Appendix F to the seismic evaluation report (Reference 9) provides a summary of the results of the bolt tightness check.

' The licensee evaluated the axial (pullout) and shear capacities of the anchorages following the GlP-2 procedures. The licensee calculated the demand on the anchorage by applying the demand load at the equipment center of gravity. If the demand was less than the capacity, they

- considered the anchorage acceptable, otherwise, they declared the equipment item an outlier.

The approach and methodology employed by the licensee in verifying the adequacy of equipment anchorages are in accordance with the verification guidance in GIP-2 and hence, the l staff finds them acceptable. In Table 8-2 of Reference 9, the licensee identified a number of i outliers related to the equipment anchorage deficiencies, some of which have not yet been completely resolved. The licensee plans to resolve the outliers involving " capacity exceedance" using the IRS obtained from the realistic median-centered analysis (Reference 16). The licensee is expected to resolve the remaining anchorage outliers in accordance with GIP-2

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7 2.4.4 ' Seismic Soatial Interaction Eva!ustion As a part of the screening provision for verifying the seismic adequacy of an item of mechanical or electrical equipment, the licensee addressed potential spatial interaction. effects for the

equipment in Section 4.1 A of the seismic evaluation report. This serves to' ensure that there are no adverse seismic spatial interactions between the equipment under consideration and nearby equipment, systems, and structures which could cause the equipment to fail to perform its intended safe shutdown function. The interactions of concern are (1) proximity effects, (2) structural failure and falling, and (3) flexibility of attached lines and cables. Guidelines for judging interaction effects, when verifying the seismic adequacy of equipment is presented in Appendix D of GIP-2.

During the plant walkdowns at Quad Cities, the SRT identified a few interaction findings. These interaction findings are listed in Table 8-2 of the seismic evaluation report, along with the licensee's proposed approaches for resolution. The staff finds the proposed resolutions reasonable and acceptable.

2.5 Tanks and Heat Exchancers The licensee identified 24 tanks and heat exchangers that required seismic adequacy evaluations. In Section 6.1 of the Seismic Evaluation Report, the licensee indicates that the large flat-bottom vertical tanks were evaluated for shell buckling considering the effects of hydrodynamic loadings and tank wal! flexibility. In response to the question regarding the details of this evaluation however, the licensee stated (Reference 12), *there are no large flat-bottom vertical tanks in the Quad Cities Safe Shutdown Equipment List."

Where applicable, the' licensee has used Section 7 of GlP-2 for verifying the adequacy of tanks and heat exchangers. Table 6-1 (Reference 9) shows a summary of the evaluation results for tanks and heat exchangers at Quad Cities. The table identified the following two outliers:

-(1) the evaluation of the fuel oil day storage tank indicated that the fuel piping may not be flexible enough to withstand the postulated seismic displacements, and one bolt would be subjected to bending; and (2) at the time of the evaluation of RHR heat exchanger supports, the licensee's svaluation of the adequacy of the support steel was not yet completed. For the second outlier, the licensee indicated in Reference 12 that it made modifications to upgrade the RHR heat exchanger supports.' This is acceptable to the staff. The final resolution of the first outlier remains to be completed by the licensee.

Based on the overall process documented in the licensee's summary report for verifying the  !

adequacy of safe shutdown tanks and heat exchangers, the staff finds the licensee's approach {

in general agreement with GIP-2 provisions and is, therefore, acceptable. The licensee has l

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committed to complete the resolution of the remaining outlier in accordance with GlP 2 i provisions.

i 2.6 Cable and Conduit Raceways Supports The Quad Cities raceway systems are primarily of light steel strut frame, steel angle frame, or rod-hung construction. The hangers of frame construction vary from very simple wall mounted i

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brackets supporting a few conduits to floor, ceiling, floor-ceiling, floor-wall and ceiling-wall  !

' mounted multi tier frames supporting mostly cable trays and some conduits. The rod-hung  !

trapeze hangers vary from single to multi-tier depths and also support mostly cable trays and some conduits.

Cable trays are primarily of ladder or solid bottom type construction with 6-inch side rails and vary in width from 12 to 44 inches. The trays are sometimes sprayed with fire retardant or have steel covers. Conduits vary up to 5 inches nominal diameter in size and are of rigid steel  ;

material (standard schedule pipe). The trays 'and conduits are secured to hangers using j standard tray clamps (clips), pipe clamps, or bolting. )

in Section 7 of'the seismic evaluation report (Reference 9), the licensee summarized the procedure used in review of the raceways at Quad Cities. They' performed the review as

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specified in Section 8 of GIP-2. They walked down the raceway systems, enecked against tha

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~ " Inclusion Rules" and "Other Seismic Performance Concems," as specified in Section 8.2 of j GIP-2, and they examined them for seismic spatial interactions with adjacent equipment and structures.

The licensee determined the scope of the review by studying the plant layout drawings and "

walking through the plant to determine how cabling is routed to the areas of the plant containing the SSEL equipment. The licensee's review included:

(1) ' All elevations of the reactor buildings, excluding elevations 666 feet and 690 feet, and selected non-safety areas of elevations 639 feet and 647 feet.

(2) _ Selected vital areas of the turbine building including the electrical equipment room, diesel generator (DG) rooms, safe shutdown pump room,4 KV switchgear area, RHR and high-pressure coolant injection (HPCI) rooms, and battery rooms and electrical bus areas of elevations 615 feet and 623 feet.

(3) . . The control room.

(4) The raceways suspended 595 feet to 554 feet elevation from above the circulating water pumps, and the raceways in the service water pumps area of the crib house.

The licensee performed the bulk of ti.e walkdown in August 1995. They performed the

. remainder of the walk down, which comprised the Unit 2 torus corner rooms, the Unit 1 and

- Unit 2 turbine building common area, and the Unit 1 and Unit 2 diesel generator building and '

switchgear rooms, in February 1996.-

The limited analytical reviews (LAR) evaluated the seismic capability of the raceway supports which were selected as representative, worst case examples of the major types of raceway support configurations. The licensee selected twelve (12) supports for evaluation. The licensee performed evaluations using the guidelines in Section 8.3 of GIP-2. The results of the LAR are summarized in Table 7.2 'of the Seismic Evaluation Report and the outliers are discussed in Table 7.4.

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The staff's review of Table 7.4 indicated that the licensee identified eight outliers out of 12 LARs. In response to the staff's question regarding its basis for not expanding the sampling for LARs, the licensee stated that the LARs were selected for worst case examples for each type of

- cable tray hanger. Resolutions will be applied to hangers that fit that outlier hanger type, as

{ needed. Therefore, there is no need to expand the reviews to a larger sample size (References 9 and 12). The staff interprets the licensee's response to mean that the outlier resolution is applicable to all cable tray supports represented by the ones selected for LARs. On this basis, the staff finds this response acceptable.

Table 3 of Reference 15 represents a revision to Table 7.4 of Reference 9. In Table 3, the licensee indicated the resolution of LARs 001,006 and 008, based on the limit analysis allowed by Section 8.4.8 of GIP-2. LAR 007 was shown to have no margin beyond the SSE demand.

In response to the staff's question on acceptability of this support, the licensee stated in Reference 13 that the cable trays and supports in question were added as part of the station black out (SBO) modification, which added the SBO building containing the SBO DGs and their auxilir. ries. The licensee indicated that these cable trays and supports are not included in the i SSEL, and are non-safety related. The licensee also indicated that these supports are designed to the 1991 Edition of the Uniform Building Code and that postulated failure of these

( supports will not affect safety related or SSEL equipment, since there is no equipment of this type in the area. Based on the above argument and the fact that the supports in question meet the SSE demand, the licensee concluded that the support is operable and acceptable. The staff considers this explanation acceptable for resolution of this outlier.

For the resolution of the remaining four outliers (LARs 002,004,011, and 012), the licensee indicates that some additional walkdown? and hardware modifications would be needed to resolve these outliers.

The staff finds thr.t, assuming satisfactory resolution of the four outliers, the process used for verifying the seismic adequacy of the cable tray supports is acceptable.

2.7 Essential Relays

" The ligensee began the relay evaluation with the creation of d relay list which documents a detailed circuit evaluation for each piece of equipment identified in the SSEL. They perforrrad the detailed circuit evaluation O identify those relays required to function to assure availat;ility of

' safe shutdown equipment and, thus. included only those contacts directly involved with the operation of the specified piece of equipment. Therefore, devices controlling nonessential equipment, annunciators, and alarms were not included on the list. The licansee checked for genericahy rugged devices such as solid-state relays and mechanically actuated contacts which were screened as "not vulnerable" to chatter. The licensee screened those contacts for which it was determined that chatter would not adversely impact equipment operation as " chatter acceptable." in addition, the licensee determined those relays for which operator action would

! be required during the design seismic event to reset /respcr.J to the ccncquences of relay chatter affecting equipment availability. The staff discusses this topic in Section 2.8 of this safety evaluation under Human Factore Aspects. Comed considered remaining contacts to be potentially seismically vulnerable.

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The licensee evaluated the seismic adequacy of the remaining relays and other contact devices by comparing the seismic capacity of the specific relay types with the plant specific seismic demand.' They determined the seismic demand by modifying the floor response spectra at the base of the cabinet er panel to account for structural amplification between the cabinet base and the location of the device mounted within the cabinet. Comed used generic in-cabinet amplibcation factors and factors of safety provided in GIP-2 to account for structural amplification. The licensee identified low ruggedness or

• bad actor" relays during the seismic

. . capacity screening.- Many of the devices passed the seismic capacity screening process and required no further evaluation. Some relays did net pass the seismic capacity meening because either the seismic demands on these devices were higher than their published capacities or the selsmic capacity data was unavailable for the specific relay models.

The licensee considered the relays that could not be screened using the methods described.

above to be outliers. The licensee provided a complete list of outliers and its planned methods of resolution in Appendix G to the relay evaluation report, which was attached to the licensee's l summary report (Reference g). i in accordance with the GIP-2 guidelines, the licensae performed walkdowns of re:ays and their 4 enclosures. The purpose and scope of these walkdowns was to:

(1)- Obtain, as necessary, information needed in determine cabinet types and specific I in-cabinet amplification factors for seismic screening.

(2). Verify the seismic adequacy of cabinets or enclosures which contain essential relays.

(3) Spot-check mountings of essential relays to determine if they are in accordance with manufacturer's recommendations.

(4) Confirm that the relay types and locations are consistent with the documentation sources used during the relay circuit evaluations.

Following the detailed circuit evaluation and relay walkdosh, the licensee evaluated all the remaining contacts considered to be potentially seismically vulnerable for seismic adequacy.

According to the licensee (References 9 and 12), a total of 1216 essential contacts (for both Units) were initially evaluated using the seismic capacity screening methodology.

First, the licensee identified a total of 10 ' bad actor" devices, which includes 1 General Electric-type HGA relay,2 Westinghouse-type SG relays,4 Westinghouse-type SV relays, and 3 General Electric type CEH relays. Ne2, they screened out devices located on the diesel generator skids and on panels mounted on the skids as having sufficient capacity, since relays on a reciprocating engine skid are exposed to high vibration levels during normal operation.

The licensee stated that the SRT also performed spot checks of the mounting of these devices, and that the remaining relays were evaluated for seismic adequacy using the seismic capacity data contained in EPRI NP-7147-SL (Reference 19), and EPRI NP-5223-SL (Reference 20).

The use of relay GERS as published in these references provided a pnmary means of establishing relay seismic capacity at Quad Cities.

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-e The seismic demand on relay devices was determined using the criteria presented in GIP-2 and EPRI NP-7148 (Reference 21). In general, the seismic demand on relays was determined by modifying the floor response spectra at the base of a relay cabinet or panel to account for structural amplification between the floor and the relay mounting location.

As stated in Psfe'rence 12, of the 1216 contacts evaluated by the ilcensee using the seismic capacity screening process,654 passed. The remaining 562 contacts (relating to 369 individual devices) that did not pass, were further categorized by the licensee as " bad actor" relays,203 relays for which no GERS are available,21 relays for which GERS may be available, but the specific caveats are not met, and 126 relays where the relay capacity is exceeded by the demand. In addition, one device fa:!ed due to mounting al6ne, three relays failed due to insufficient informatlon regarding the essential contact configuration, and two devices failed because their type could not be determined from the drawings or the initial walkdown.

Of the 126 relays for which demand was greater than capacity, a large number are located at the 4kV switchgear (SWG"?) and mounted on the cubicle doors. The demand at some SWGR, such as Panels 2251(2) - 86&B7 (with 25 outliers), is so high that even the most ruggcd types of relays would fail. In Attachment G to the Relay Evaluation Report, the licensee stated that a panel amplification factor lower than the generic value of seven used will be justified. Use or additional bracing at the SWGR will also be considered in order to reduce the amplification.

Comed states that approximately 30 outliers are located in panels 2201(2)-32 which would require improvements to the mounting of the panelitself, in order to sufficiently reduce demand for the relays. For the remaining " capacity exceeded" outliers, the resolution involves the reanalysis of the panel amplification factors or a reevaluation of the circuit to determine if the logic allows other screenable relays to be made essential and the outlier made " chatter acceptable." The licensee will modify the panel and/or relay if this fails.

3 As stated previously, the licensee determined that the 21 devices for which GERS were available, did not meet the required caveats.' ln addition, the 206 relays for which GERS are not available were grouped into several types of similar relays. For these groups, the licensee stated that existing test data will be searched or the specific relay type will be sent for testing.

. Replacement of relays is also considered an option if the methods listed above do not work or if it is more cost effective than testing of a single outlier, in an e-mail transmittal (Reference 22), the licensee provided an updated status of the outlier resolution and stated that, to date,112 relay outliers will be resolved by engineering, and another 151 relays will require physical modification. Assuming satisfactory resolution of the

outliers, the staff considers the essential relay evaluation adequate since it meets the provisions of GIP-2.

2L8 Human Factors Asoects

' GlP-2 describes the use of operator action as a means of accomplishing those activities required to achieve safe shutdown. Section 3.2.7, " Operator Action Permitied," states, in part, that timely operator action is permitted as a means of achieving and maintaining a safe shutdown condition provided procedures are available and the operators are trained in their pi. , , , ,. . . . . . . . . . . .. .

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1 use. Additionally, Section 3.2.6, " Single Equipment Failure," states that manutil operator action i of equipment which is normally power operated is permitted as a backup operation provided l that sufficient manpower, time, and procedures are available. _ Section 3.2.8. " Procedures,"

states, in part, that procedures should be in place for operating the selected equipment for safe shutdown and operators should be trained in their use. It is not necessary to develop new procedures specifically for compliance with the USl A-46 program.

In Section 3.7,? Operations Department Review of SSEL," of GlP-2, SQUG also described three methods for accomplishing the operations department reviews of the SSEL against the plant operating procedures. Licensees were to decide which method or combination of methods was I to be used for their plant-specific reviews. These methods included:

1. A " desk-top" review of applicable normal and emergency operating procedures.

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2. Use of a simulator to model the expected transient, and 3.

Performing a limited control room and local in-plant walk-down of actions required by plant procedures.

The staff's evaluation of the SQUG approach for the identification and evaluation of the SSEL, including the use of operator actions, was provided in Section 11.3 of the staff's SSER on GIP-2. The staff concluded that the SQUG approach was acceptable.

The staff's review of the summary report (Reference g) focused on verifying tirat the licensee had used one or more of GIP-2 methods for conducting the operations depMment review of the SSEL, and had considered aspects of human performance in deternWning vd at operator actions could be used to achieve and maintain safe shutdown (e.g., resetting rt%ys, manual operation of plant equipment).

The licensee provided information which outlined the use of the " desk-top" and simulator review methods by the operations department to verify that existing normal, abnormal and emergency -

operating procedures were adequate to mitigate the postu!ated transient and that operators could place and maintain the plant in a safe shutdown condition. The licensee determined that the systems and equipment selected for seismic review in the USl A-43 program are those for which normal, abnormal, and emergency operating procedures are available to bring the plant from a normal operating mode to a hot shutdown condition. , The Quad Cities Technical Review Board reviewed the shut down paths which were selected and were run on the Quad Cities simulator and, as a result, the existing procedures were determined to be adequate. The licensee provided assurance that ample time existed for operators to take the required actions to safely shut down the plant. This had been accomplished during validation of the pertinent )

plant operating procedures related to the licensee's Upciated Final Safety Analysis Report (UFSAR), Chapter 15, Accident Analysis for the loss of offsite power (LOOP) transient which preceded the A-46 program review. Since these plant procedures had already been valk'ak,c

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to ensure that adequate time and resources are available for operators to respond to a LOOP incident,it was pot necessary to re-validate these procedures for the USl A-46 program.

The staff verified that the licensee had considered its operater 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. The operations department verified that all actions necessary to safely shut down the plant were included in existing normal, abnormal, and emergency operating procedures, and that no procedural modifications were re?uired as a result of the A-46 review. The licensee verified that the only additional operator actions, beyond those associated with the LOOP accident scenario, which must be performed to bring the plant from a normal operating mode to a hot shutdown condition are those specifically associated with the vibrator / motion of the SSE. The specific areas where operator actions would be required included:

1.

Operator action may be required to reset low pressure coolant injection (LPCI) loop select logic.

2. Operator action may be required to restore off-site power.

3. Operator action may be required to reset the fire detection relay seal-in which would prevent the DG heeting, ventilation, and air conditioning (HVAC) from starting and running.

4. Operator action may be required to trip the DG cooling water pump when its corresponding DG is not running.

5. Operator action may be required to reset the condenser associated with control room HVAC prior to use.

In each case the specific actions were discussed with the operations department, during the relcy screening process, to ensure that the actions could be performed in the required amount of time with normally available resources. The results of the review of these operator actions by the operations department verified that each of the actions was adequately covered by existing procedural guidance, and that adequate resources including time availability to take such actions, 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 to substantiste that potential challenges to the operator were explicitly reviewed during validation of the pertinent plant operating procedures related to the licensee's UFSAR, Chapter 15, Accident Analysis for the Loss of Offsite Power transient which preceded the A-46 program review, in addition, the licensee explicitly evaluated the potential for local failure of architectural features and the potential for adverse spacial interactions in the vicinity of safe shutdown equipment, where local operator action may be required, as part of the GIP-2 process. As a result of the review several seismic and housekeeping issues affecting the control room were noted and resolved, including tightening and repairing several control panels, securing overhead lighting fixtures, and relocating or removing transitory equipment (e.g., book cases) which could pose a hazard. The licensee performed seismic interaction reviews which

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.t 14 eliminated any concems with the plant components and structures located in the immediate vicinity of the components which had to be manipulated. Therefore, the potential for physical barriers resulting from equipment or structural earthquake damage which could inhibit operator ability to access plant equipment was considered, and eliminated as a potential barrier to successful operator performance.

' Ths licensee has provided the staff with sufficient information to demonstrate conformance with the NRC-approved review methodology outlined in GlP-2 and is, therefore, acceptable.

2.9 Outlier Identification and Resolution As previously stated, an outlier is defined as an item of equipment which does not meet GIP-2 screening guidelines. The licensee may show an outlier to be adequate for seismic loadings by performing an additional evaluation using afternate methods or seismic qualification techniques acceptable to the staff. Based on the screening criteria stated in Section 2.4, the licensee identified a number of equipment items as outliers during the walkdowns by the SRT. In - I Section 4.6 of the seismic evaluation report, the licensee indicated that a total of 114 out of 380 mechanical and electrical equipment items were initially declared outliers, as indicated in Table I

- 8.2 of the report. Included in the table are a number of outliers related to the equipment anchorage deficiencies. The licensee plans to resolve the outliers using IRS determined from RMC analysis'(Reference 16). This includes some of the identified anchorage outliers which remain to be resolved by the licensee. The licensee must ensure that appropriate factors of conservatism, as stipulated in Table 4-3 of GIP 2, are incorporated in determining the adequacy of anchorages.

The licensee's evaluation of the fuel oil day storage tank identified it as an outlier. This is due to inflexibility of the fuel piping and bending of one associated bolt. This too remains to be resolved by the licensee.

In its evaluation of cable trays / raceways, the licensee indicated in Table 7.4 of Reference 9 that they identified eight (8) outliers out of 12 LARs. The licensee indicated in Reference 12 l

' that the resolutions will be applied to hangers that fit that outlier hanger type, as needed . The '

staff interprets the licensee's response to mean that the outlier resolution is applicable to all cable tray supports represented by those selected for LARs, and considers the response acceptat:le.

As stated previously, the licensee indicated in Reference 9 that for the resolution of the four outliers (LARs 002, 004, 011, and 012), some additional walkdowns and hardware modifications would be required.

In Reference 22, the licensee provided the following breakdown of an updated list of SQUG outliers and the tentative plan for resolution:

Mechanical Eauicment To be resolved via engineering - 6 Possible physical modification - 11

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. 15-Electrical Eauioment

To be resolved via engineering - 30 Possible physical modification - 18 BR.18XA To be resolved via engineering - 112 Possible physical modification - 151 Cable Travs/Raceggy3 Possible physical modification - 25 supports - 4 The licensee stated in Referer ce 22 that the items to be resolved via engineering, have been .

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evaluated sufficiently to ensure that they would pass; although the analysis packages have not yet been finalized.

I According to Reference 9, the licensee plans to address all Quad Cities A-46 outliers by the end of the second refueling outage for each unit following receipt of the staff's safety  ;

evaluation. In Reference 10, the staff requested the licensee to provide the justification for assuring operability of the affected systems and components while a number of safety-related corrponents in the safe shutdown path have been identified as outliers. In Reference 12, the licer:see stated that it has reviewed all outliers against its seismic design basis in accordance with the gip-2 methodologies The licensee has generated Problem identification Forms (PlFs) i for outliers which were identified by the SRT as possible operability issues. They then reviewed the operability of components and systems utilizing Quad Cities Procedure QCAP 0230-07,

" Operability Determination." The licensee has determined that the equipment meets its design basis. This is acceptable to the staff.

Programmatic Solutions, in Northport, NY, was contracted by the licensee to perform the

' independent peer review. The peer review report was provided as Appendix E to the seismic

. evaluation report. The scope of the peer review performed for Quad Cities includes

(1) evaluation of the SSEL

(2) the essential relay list; (3) walkdown information (principally SEWS), including potential seismic interactions, anchor bolt tightness check, and the performance of the SRTs; (4) a review of calculations for equipment anchofi.ge and qualification; and (5) outlier resolution.

'ihe peer reviewer performed a walkdown of the plant, on May 6 and 7,1996. During the site visit, a sample of the SEWS forms Filed out by the SRT were reviewed to determine if the documentation was appropriate. In addition, the peer reviewer reviewed the Quad Cities, Units 1 and 2, seismic design basis, seistWe verification data sheets (SVDS), walkdown resumes, walkdown comments by the SRT, summary of outlier recommendations, photographs

taken during the walkdown, and the current results of the Quad Cities A-46 implementation.

Based on the peer review walkdown and the review of the information provided by the licensee, including outlier resolutions performed by the licensee, the peer reviewer concluded that the methods used for the Quad Cities, Units 1 and 2, implementations are appropriate, correctly implemented, and the results and the recommended actions are reasonable. The staff finds the peer reviewer's assertion acceptable.

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In Reference 10, tho' staff raised a question regarding the outlier resolution for raceway

! hangers, provided in Table 7.3 of the Seismic Evaluation Report. The resolutions a' ppeared to

' have been performed bas _ed on the high-ec,hfidence-low-probability-of-failure (HCLPF) analysis and the conservative deterministic failure margin (CDFM) methodologyc Because of the uncertainty of their conservatism, these methodologies have not been endorsed by the staff for

. the analysis of safety-related systems and components, including the resolution of mechanical,

" electrical, and structural component outliers in the USl A46 program. The licensee stated in its response (Reference 12),that the capacity of raceway hangers was calculated in accordance with the GIP-2 guidelines as approved by the NRC. CDFM methodology and HCLPF values were not used for the resolution of these outliers. The licensee further stated that only methodologies acceptable W the staff and in accordance with GIP-2 have been and will be used for outlier resolution, including cable tray outliers.. The staff finds the response acceptable.

3.0

SUMMARY

OF MAJOR STAFF FINDINGS '

Based on its review of the licensee's submittals, the staff found that the licensee's USl A-46

. program has, in general, followed GIP-2 guidelines, and that no programmak: or tignificant deviations from the guidelines were made during the USl A 46 implementation process at Quad Cities. The staff found that the licensse's approach for determining equipment seismic demand is consistent witu the GIP-2 provisions and is acceptable. Specifically, based on the evaluation of the licensee's method of generating the seismic demand for equipment, the staff concludes L that the use of Method A as stipulated in Table 4-1 of GIP-2 for defining the seismic demand is acceptable. The staff also finds the use of RMC spectra, as the demand spectra, for outlier evaluations acceptable.' The licensee should ensure that the additional factor of conservatism, as stipulated in Table 4-3 of GIP-2, is incorporated in determining the adequacy of anchorages.

The staff also determined that the licensee has presented acceptable approaches for resolving all the identified outliers in Tables 6.1,7.3, and 8.2 of the seismic evaluation report and

Appendix G to the relay evaluation report. The licensee should resolve all remaining outliers as stated in Section 2.g in accordance with its scheduling commitment.

The staff determined that, upon completion of all the necessary corrective actions for the identified equipment and relays, the Quad Cities USl A46 program will be in conformance with GlP-2 provisions and, therefore, will be acceptable.

4.0 CONCLUSION

in general, the licensee conducted the USl A46 implementation in accordance with GIP 2. The licensee's A-46 implementation program did not identify any instance where the operability of a particular system or component was called into question. The staff's review of the licensee's implementation program did not reveal any significant findings that would suggest inadequacy of the licensee's A-46 program in light of the GIP-2 guidelines. The staff concludes that the licensee's USl A-46 implementation program has, in general, met 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 have resulted in safety enhancements which, in certain aspects, are beyond the originallicensing basis. As a result, the licensee's actions pro ~ vide sufficient basis to close the USl A46 review at the facility. The staff also L

1 concludes that the licensee's implementation program to resolve USl A-40 at the facility has adequately addressed the purpose of the 10 CFR 50.54(f) request. Licensee activities related to the USI 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, Neil Smith on June 19,1998 (Reference 23). The primary consideration in the licensee's determination to incorporate GIP-2 in the licensing basis, is completing the resolution of all the identified outliers, in accordance with its commitments and the GIP 2 provisions. Where plants have specific 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. An overall conclusion that no unresolved safety questions (USQ) are involved is acceptable so long as any changes in specific commitments in the licensing basis have been thoroughly evaluated in reaching the overall conclusion.

v If the overall cumulative assessment leads a licensee to conclude that a USQ is in' olved, incorporation of the GlP-2 methodology into the licensing basis would require the licensee to seek an amendment under the provisions of 10 CFR 50.90.

Principal Contributors: A. J. Lee, DE/EMEB H. Ashar, DE/EMEB X. Desai, DSSA/SRXB G. Galletti, DRCH/HOHB R. Rothman, DE/EMEB Dated: September 21, 1999

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18-5.0 References

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1.

Regulatory Guide 1,100, " Seismic Qualification of Electric and Mechanical Equipment for Nuclear Power Plants," Revision 2,1987.

2, IEEE Standard 344-1975, "lEEE Recommended Practices for Seismic Qualification of I Class 1E Equipment for Nuclear Power Generating Stations," dated January 31,1975.

3. NRC Standard Review Plan (NUREG-0800), Section 3.10, " Seismic and Dynamic Qualification of Mechanical and Electrical Equipment," Revision 2, July 1981.

4. NRC Generic Letter 87-02, " Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors, Unresolved Safety issue (USI) A-46," February 1987.

. 5. " Supplemental Safety Evaluation Report No. 2 on Seismic Qualification Utility Group's Generic Implementation Procedure, Revision 2, corrected February 14,1992."

6. " Generic implementation Procedure (GlP) for Seismic Verification of Nuclear Power Plant Equipment," Revision 2, corrected February 14,1992, Seismic Qualification Utility Group.

7. Letter, Commonwealth Edison Company to NRC Document Control Desk, " Comed Response to Generic Letter 87-02, Supplement 1 on SQUG Resolution of USl A-46, Dresden Nuclear Power Station, Units 2 and 3, Quad Cities Nuclear Power Station, Units 1 and 2, and Zion Nuclear Power Station, Units 1 and 2," dated September 21,1992.

8. Letter, NRC to Comrnonwealth Edison Company, " Evaluation of Dresden Nuclear Power Station, Units 2 and 3, Quad Cities Nuclear Power Station, Units 1 and 2, and Zion Nuclear Power Station, Units 1 and 2120-day Response to Supplement No.1 to Generic Letter 87-02 (TAC Nos. M69442, M69443, M69476, M69477, M69492 and M69493)," dated November 20,1992.

9. Letter, Commonwealth Edison Company to NRC Document Control Desk, " Summary Reports for Resolution of Unresolved Safety lasue A-46, Generic Letter 87-02, Quad Cities Nuclear Power Station Units 1 & 2," dated June 28,1996.

10. Letter, NRC to Commonwealth Edison Company, " Request for Additional Information,"

dated August 19,1997.

11, Letter, NRC to Commonwealth Edison Company, " Request for Additional Information,"

dated April 29,1998.

12. Letter, Commonwealth Edison Company to NRC Document Control Desk, " Response to Request for Additional Information - Unresolved Safety issue A-46, Seismic Qualification of Equipment in Operating Plants, Quad Cities Nuclear Power Station Units 1 & 2," dated October 24,1997.

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k 13. Letter, Commonwealth Edison Company to NRC Document Control Desk, " Response to Request for Additional Information - Unresolved Safety issue A-46, Seismic Qualification of Equipment in Operating Plants, Quad Cities Nuclear Power Station Units 1 & 2," dated November 25,1997.

14. Letter, NRC to Commonwealth Edison Company, dated March 24,1998.

15. Letter, Commonwealth Edison Company to NRC Document Control Desk, " Response to Request for Additional Information - Unresolved Safety issue A-46, Seismic Qualification of

' Equipment in Operating Plants, Quad Cities Nuclear Power Station Units 1 & 2," dated

- July 31,1998.

16. Letter, Commonwealth Edison Company to NRC Document Control Desk, " Resolution of Unresolved Safety issue (USl) A-46, Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors," dated March 19,1999.

17. Letter, Commonwealth Edison Company to NRC Document Control Desk,"NRC Evaluation of Comed Response - AdditionalInformation," dated January 15,1993.

18. Letter, NRC to Commonwealth Edison Company," Evaluation of Quad Cities Procedure for Developing in-Structure Spectra," dated June 7,1993.

19. EPRI NP-7147-SL, " Seismic Ruggedness of Relays, Final Report," dated August 1991.

20. EPRI NP-5223-SL, " Generic Seismic Ruggedness of Power Plant Equipment (Revision 1)"

dated August 1991.

21. EPRI Report NP-7148-SL, " Procedure for Evaluating Nuclear Power Plant Relay Seismic Functionality,". dated December 1990

22. E-Mail Letter, Commonwealth Edison Company (M. Wagner) to NRC (R. Pulsifer), dated July 16,1999.

23. Letter, Brian W. Sheron (NRC) to Neil Smith (SQUG), dated June 19,1998.