ML20199G467

SER Accepting USI A-46 Implementation for Plant

ML20199G467
Person / Time
Site:	Calvert Cliffs
Issue date:	01/20/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20199G418	List: ML20199G412 ML20199G467
References
REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR NUDOCS 9901220303
Download: ML20199G467 (15)

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- SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR USrA;46 PROGRAMTMPLEMENTATION-

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R CALVERT CUFFS NUCLEAR POWER PL ANT. UNIT NOS.1' AND 2 j

DOCKET NOS. 50-317 AND 50-318

1.0 BACKGROUND

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 described the process for resolving USl A-46, and 1 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 (GIP-2, Reference 1).

On May 22,1992, the NRC issued Supplement 1 to GL 87-02, along with the staff's Supplemental Safety Evaluation Report No. 2 (SSER-2, Reference 2), pursuant to the provisions of 10 CFR 50.54(f), which required that all addressees submit either: (1) a commitment to use both the SQUG commitments and the implementation guidance described in GlP-2, as supplemented by SSER 2, or (2) an alternate method for responding to GL 87-02. ,

The supplement also required that those addressees committing to implement GlP-2 submit an I implementation schedule and detailed information on the procedures and criteria used to generate the in-structure response spectra (IRS) to be used for USl A-46.

By letter dated September 18,1992 (Reference 3), Baltimore Gas and Electric Company (BGE), the licensee, responded to Supplement 1 to GL 87-02 for the Calvert Cliffs Nuclear Power Plant, Unit Nos.1 and 2 (CCNPP). In the letter, BGE committed to abide by the commitments made by SQUG in GIP-2, including the clarifications, interpretations, and exceptions reported in SSER-2. The staff indicated its acceptance of the licensee's response by letter dated November 20,1992 (Reference 4).

By letter dated June 28,1996 (Reference 5), BGE submitted a summary report containing the results of the USl A-46 program implementation at CCNPP By letters dated March 23,1998 (Reference 6), and September 22,1998 (Reference 7), BGE sent supplemental information and clarification in response to the staff's requests for additionalinformation (RAls), dated December 19,1997 (Reference 8), and March 2,1998 (Reference 9), respectively. On October 30,1998, a conference call took place between the CCNPP engineers and the NRC ,

staff to discuss the licensee's March 23,1998, submittal. In response to questions raised l during that telephone conference, the licensee submitted additional information in a letter l dated November 12,1998 (Reference 10).

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f 9901220303 980120 I DR ADOCK 050003 7 Enclosure

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This report presents the staff's evaluation of the licensee's USl A-46 implementation program.

The evaluation is based on the staff's review of the Summary Report and of the supplemental -

information, clarification, and documentation submitted by the licensee in response to the

' staff's' RAlt.- -

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2.0 DISCUSSION AND EVALUATION u

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l The Summary Report (Reference 5) discusses the results of the licensee's implementation of l

l the USI A-46 program at CCNPP. The report discusses a safe shutdown equipmeat list i (SSEL) and documents the screening verification and walkdown of mechanical and electrical l equipment and the relay evaluation. The report also: (1) documents the evaluation of seismic adequacy for tanks, heat exchangers, and cable and conduit raceways, (2) identifies outliers, and (3) proposes resolutions including projected schedules.

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

CCNPP was designed using a Housner-type spectrum with a horizontal peak ground l l acceleration (PGA) of 0.15g for the safe-shutdown earthquake (SSE)(Reference 5). All of the components in the SSEL are housed in one of the followin; structures: auxiliary building (AB),

intake structure (IS), tank farm (TF), fire pump house (FPH.), reactor containments (RC), and turbine building (TB). The seismic demand of the equipment on the SSEL was determined based on the CCNPP licensing-basis IRS, which were considered " conservative design" as per GlP-2 Section 11.4.2 (Reference 1). The licensee submitted these IRS in its 120-day response (Reference 3) and the NRC staff accepted them (Reference 4).

In its 120-day response, BGE said that it would use the GIP-2 options for " median-centered

and " conservative design" IRS, as appropriate, depending on the building, the location of the ,

equipment, and the equipment characteristics. CCNPP is located on a deep, soft soil, site and soil-structure interaction (SSI) effects play an important role in the structural response to l seismic motions. During the A-46 program implementation, BGE concluded that the IRS i presented in the 120-day response were too conservative with respect to modeling the SSI

effect (e.g., the soil damping, used in the design-basis structural models, was less than 10 percent, accounting for both material and radiation damping). Therefere, BGE prepared a new set of realistic, median-centered response spectra, as described in Appendix H to the Summary Report. These IRS were generated in accordance with detailed two dimensional seismic analyses, including the SSI effect, using the FLUSH finite element program. The ground input spectrum to the FLUSH analyses was selected based on Option b of the four options for the ground response spectrum presented in GIP-2, Section l1.4.2.4, Method B. This is the NUREG/CR-0098 (Reference 12) 84 percent non-exceedance percentile (NEP) spectral shape anchored to the design basis SSE PGA (0.15g). Subsequently, an artificial accelerogram compatible with the NUREG/CR-0098,84 percent NEP spectrum was generated for use in the seismic SSI analyses. Furthermore, the licensee demonstrated that sufficient power exists in the accelerogram by comparing the power spectral density (PSD) function of the accelerogram, with the PSD function defined for the Regulatory Guide (RG) 1.60 spectrum, as given in Appendix A to Standard Review Plan (SRP) Section 3.7.1.

In the preceding analyses, each structure was assumed to be founded at the ground surface, and the embedment effect was not considered. The soil at the CCNPP site can be

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characterized as deep, soft, sandy silt or silty sand type. The median shear wave velocity is -

assumed to be 760 fps. The lowerand uppertounds were~ determined to be 480 fps and 1180 fps, respectively. The best-estimate, upper bound, and lower-bound values of the _ _ _ _ _

effective soil hysteretic damping ratio were 8 percent,10 percent a:d 6 percent& respectively.

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I ne stan finds the licen'see's' approach for determining the seismic demand consistent with the a provisions of GIP-2 and, therefore, acceptable. .-

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2.2 Seismic Evalua. tion Personnel The CCNPP seismic evaluation was conducted by a multi-discipline project team. The team contained BGE and contractor employees. The seismic capability engineers (SCEs) for the CCNPP walkdown consisted of engineers from BGE, MPR Associates, Inc., EQE Engineering Unsultants, Inc., and Gilbert / Commonwealth, Inc., and are identified in Section 3 of Reference 5. Their resumes are found in Appendix A to Reference 5. Most of the SCEs have completed SQUG training in their areas of invcivement.

The licensee stated that the system engineers assisted the SCEs for the plant-specific information regarding safe-shutdown systems, equipment functions and locations. Personnel in the CCNPP Operations Department reviewed the items on the SSEL to ensure they are compatible with the normal and emergency operating procedures used for Units 1 and 2. The relays associated with items on the SSEL were evaluated by a lead relay / electrical engineer, whose resume is found in Appendix l to Reference 11. Dr. John D. Stevenson (a recognized expert in seismic evaluation matters) of Stevenson & Associates served as the third-party reviewer for the CCNPP USI A-46 implementation program.

The staff finds that the qualifications of the I;censee's seismic evaluation personnel meet the t provisions of GIP-2 and the staff's SSER-2, and are, therefore, acceptable.

2.3 Safe-Shutdown Path GL 87-02 specifies that the licensee should be able to bring the plant to a hot standby condition and maintain it there for 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 licensee, in its submittal of June 28,1996 (Reference 5), addressed the following plant safety functions: reactor reactivity control, pressure controi, inventory control, ano decay heat c removal. Primary and attemate safe-shutdown success paths with their support systems and )

instrumentation were identified for each of these safety functions to ensure that the plant is caphble of being brought to a hot standby condition and maintain it there for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following an SSE. Since hot shutdown condition is not part of the CCNPP licensing basis, hot standby condition is considered the safe shutdown condition for this plant. Appendix C to Reference 5 provides the safe shutdown equipment list.

Decay hest is removed by releasing steam from the steam generators through the atmospheric dump valves (ADVs). Makeup water to the steam generators will be supplied by the auxiliary feedwater system (AFW) which takes suction from the condensate storage tanks. Once the condensate storage tanks have been depleted, the other available water source is the fire main system. Fire main water can be sent directly to the motor-driven auxiliary feed water

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pump suction or to the condensate storage tanks through emergency hose connections. Fire ,

main water can be supplied through gravity transfer or by running the diesel-driven fire pump. l l

-The plant Operating Department reviewed the eiquipment listed in Appendix C against the plant I l operating procedures a.nd operator training and concluded that the plant operating procatres , .

~ and operator training were adequate to establish . d maintain the plant in a safe-shutdown i condition following an SSE.- -

The staff concludes that the approach to achieve 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 acceptable.

2.4 Seismic Screenina Verification and Walkdown of Mechanical and Electrical Eauipment The seismic screening and walkdown included verification of items on the SSEL that are typical of those found in the SQUG experience database in the 20 classes of equipment covered in Appendix B to GlP-2 (Reference 1). The tanks and heat exchan;;ers are evaluated in Section 2.5 of this SE.

2.4.1 Eauipment Seismic Capacity Compared to Seismic Demand For the seismic capacity vs. demand evaluation of equipment in the SSEL, BGE elected Method A.1 of GlP-2, Section l1.4.2 (Bounding Spectrum (BS) vs. Design Basis SSE Ground Spectrum (GRS)), if the requirements that: (1) the fundamental natural frequency of the equipment is 8 Hz or greater, (2) the equipment is located less than 40 ft above grade, and (3) the amplification factor between the free ficld rasponse spectra and the in-structural response spectra are not more than about 1.5 v,ere satisfied (Reference 1). Otherwise, Method B.1 of GIP-2, Section 11.4.2 ("1.5 x BS vs. Conservative Design in-Structure SSE Response Spectra")

was used. When Method B.1 of GlP-2 was applied, the seismic demand of the SSEL i equipment was determined based on the licensing basis IRS, and compared with 1.5 times the

! BS. l l The licensee has stated in the Summary Report (Reference 5) that the CCNPP design-basis l GRS are enveloped by the GIP-2 BS for all frequencies. Furthermore, it is indicated in the l Summary Report that allitems on the SSEL located in the fire pump house, intake structure, j and turbine building are within 40 ft above grade; the items on the SSEL located in the l auxiliary building are within 40 ft above grade, except for those located above the floor on i

elevation 69 ft and on the roof at elevation 91.5 ft; and the items on the SSEL located in both reactor containments are within 40 ft above grade, except for those mounted above elevation 50 ft. As indicated in the Summary Report (Reference 5), the effective grade of the CCNPP Reactor containment buildings is 10 ft, and the effective grat's of all other buildings (except for the intake structure) is 45 ft. The effective grade of the intake structure is 3 ft. For all equipment located at elevations higher than 40 ft above grade, Method B.1 of GIP-2 was used for evaluating the equipment capacity vs. the seismic demand.

Although it appears that the licensee did not consider whether all the GIP-2, Section 11.4.2.3 restrictions and limitations in applying GIP-2 Method A.1 w7re satisfied at locations of interest involving A-46 equipment, the realistic, median-centered response spectra presented in Appendix H to the Uummary Report, confirm that the amplification factor between the free-field

responst spbura and the in-structural response spectra at frequencies above about 8 Hz for locations less than 40 ft above grade are about 1.5 or less.

The staff determined that the licensee has, in general, followed the GIP-2 procedures for comparinc. equipment seismic capacity to seismic demand, and considers the evaluation to be '

_ adeouate for the resolution of USl A-46. _ _-

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2.4.2 Assessment of Eauipment " Caveats" ' --

The licensee indicated in Reference 5 that the SCEs verified that the caveats listed in Appendix B to GIP-2 for each equipment class were met for CCNPP. The caveats are the inclusion and exclusion rules, which specify characteristics and features particularly important for seismic adequacy of a specific class of equipment when the equipment seismic capacity is determined by the experience-based data. The phrase " meeting the intent of the caveats" applies to equipment that does not comply with the specific wording in certain caveats but is deemed seismically adequate based on the judgment of the SCE.

The findings for equipment whose seismic adequacy was verified by meeting the caveats were documented in Column 13 of Appendix D to Reference 5. In many cases, items of equipment that did not comply with the GIP-2 caveats were considered as outliers and were documented in Section 5.3 of the CCNPP Summary Report for USl A-46 resolution. In some cases, if an item of equipment was judged to comply with the intent of the caveats, the item was considered to have met the caveat rule, in accordance with GIP 2. Equipment items that met the intent rather than the specific wording of the caveats are listed in Tables 5.2-1 and 5.2-2 of Reference 5 for Units 1 and 2, respectively.

In its response of March 23,1998, to the staff's RAI dated December 19,1997, the licensee presented supplementalinformation for some equipment items to demonstrate how the intent, if not the wording, of certain caveats was met. For instance, the SCEs noted that Panel 1N0411 top entry conduit was not flexible. This violates Bounding Spectrum Caveat No. 8 for equipment Class 20 as delineated by GIP-2. The licensee indicated that based on the installed configuration, the panel and conduit are rigidly mounted to the same structure. There is no adverse differential movement that could occur during a seismic event that would cause damage to the panel. The licensee also indicated that if a component did not meet the l wording of a caveat, and was not found as an outlier, the assessment and justification for meeting the intent of a caveat were noted on the Screening and Evaluation Work Sheets (SEWS).

l In general, the staff finds that the determination of the seismic adequacy for equipment identified in Section 5 of the CCNPP Summary Report conforms with GIP-2 guidance on the caveats, and is acceptable in those instances in which the intent rather than the wording of the caveats was met.

2.4.3 Eauipment Anchorage The equipment anchorage verification is summarized in Section 5.1.3 of the licensee's Summary Report (Reference 5). To verify the adequacy of equipment anchorage, the licensee performed field inspections (walkdowns) and analytica; calculations in accordance with GIP-2,

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Section fl.4.4. Bounding calculations were performed to verify equipment anchorage adequacy for worst-case loadings.

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The predominant anchorage type used at CCNPP is Hilti expansion anchors. Shell-type ~

expansion ~arichors, cast-in-place headed studs, embedded plates, and J-bolts are also used. _ -)

l .. ., , Approximately 130 equipment anchorage outliers were identified (for both units). About half (31 for Unit 1 and 30 for Unit 2) of these cut!iers were identified solely because they were -

anchors of the concrete expansion type, which were subjected to anchor bolt tightness checks in accordance with the requirement of GlP-2, Section ll.C.2.3. As reported in Section 5.3 of the Summary Report, all anchor bolt tightness checks have been performed. The remaining 69 anchorage outliers were identified for distribution panels and cabinets whose anchorage was judged marginal by the SRTs, or for equipment with base isolators of unknown capacities.

i According to the Summary Report, these outliers were resolved by further evaluation, or by plant modification, as summarized in Tables 5.3.1 (Unit 1) and 5.3.2 (Unit 2) of the Summary Report. All anchorage outliers, which were resolved by analyses, used the new realistic l median-centered IRS to define the seismic demand to the anchorage.

The staff determined that the licensee has,in general, adhered to the GIP-2 procedures for verifying the adequacy of equipment anchorages. Therefore, the equipment anchorage j evaluation is considered acceptable for the resolution of USl A-46. l 2.4.4 Seismic Spatial Interaction Evaluation l

l The equipment screening evaluation included evaluation for potential seismic interaction l concems following the requirements of GIP-2 (Section 11.2.4.5 and Appendix D). Enclosures containing essential relays were screened for interaction concems that might cause relay l chatter, e.g., adjacent panels not bolted together. Those items that did not meet GIP-2 l interaction requirements were identified as interaction outliers. Nearly 100 items of electrical l and mechanical equipment were identified as having interaction concerns for the two units.

Half of these (32 for Unit 1 and 21 for Unit 2) are for cabinets located in the main control room.

i These were identified because the seismic adequacy of the control room ceiling was unknown.

l Other interaction concerns were associated with suspended fire panels in contact with relay cabinets, scaffolding near components listed in the SSEL, and non-safety-related cabinets with inadequate anchorage located near components listed in the SSEL. These outhers were resolved by modifications, maintenance actions, and the removal of unsecured items from the area containing the items on the SSEL.

In regard to items on the SSEL that are located in the turbine building (TB), which is not a seismic Category I structure, BGE stated in Reference 10 that the TB was designed and constructed in accordance with the Uniform Building Code, which required the consideration of a seismic loading comparable to the seismic demand of 0.08g horizontal ar.' O.053g vertical acceleration due to the site operating basis earthquake. BGE has further stated that, during

, the plant walkdown, the TB did not exhibit any vulnerabilities. BGE also indicated in Reference 10 that 26 of the 34 SSEL items in the TB are located in the auxiliary feedwater (AFW) pump rooms, which are seismic Category I structures at CCNPP. The remaining 8 items are the 4 large control valves and their attached instruments, all of which were found to be free from the potential for adverse spatialinteractions. In its review of BGE's clarifications, the staff

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7-concluded that the spatial interaction evaluations for the 34 SSEL items in the TB are acceptable.._ -

- The staff finds the spatialinteraction evatuation consistentwith GIP 2 and adequate forTne resolution of USl A-46. -

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2.5 Tanks and Heat Exchanoers - - -

The scope of the CCNPP USl A-46 verification with respect to the seismic adequacy of tanks--- -- ,

and heat exchangers covered the following 146 items on the SSEL: 13 large flat bottomed l

atmospheric storage tanks; 41 tanks and heat exchangers on saddles; 34 vertical tanks on legs or skirts; 23 wall-mounted air tanks for air operated valves; 16 small in-line heat exchangers, collector tanks, demineralizers, and filterv 14 Nuclear Steam Supply Systems (NSSS) support coolers; and 5 level indicators mounted on large outdoor tanks.

1 The 146 tank and heat exchanger items were reviewed by the SRTs during the seismic ,

capacity walkdown, using the procedures outlined in GIP-2, Section ll.7, except for the vertical l tanks on legs or skirts, that were evaluated in accordance with EPRI NP-5228-SL (Reference 13), Revision 1, Volume 4, " Guidelines on Tanks and Exchangers," June 1991, l which is an acceptable method, according to GIP-2, Section ll.7.

As a result of the walkdown efforts, the SRTs identified a total of 43 tank and heat exchanger i outliers, which included all of the large flat-bottomed atmospheric storage tanks and 14 large i horizontal heat exchangers. The summary description and resolution of the outliers appear in Table 6-1 of the Summary Report. All outliers were resolved by one of the following three j methods: (1) additional field data, (2) additional field data and reanalysis, or (3) new SSI '

analysis using SUPER SASSI/PC. Where reanalysis was employed, the seismic demand or the new SSI analysis for outlier items, was based on the median-centered floor response spectra discussed in Section 2.1 of this SER. For tanks located in the field, the seismic demand was defined using the original free-field SSE design spectra.

i For the anchorage evaluation of outlier items, the licensee increased the expansion anchor capacity reduction factor (CRF) to 0.75 for unknown bolt-type anchors, in accordance with Revision 3 of the SOUG GlP (GlP-3), dated July 31,1995. However, on the basis of the Supplemental Safety Evaluation Report No. 3 (SSER-3) of GlP-3, dated December 4,1997, the NRC staff did not accept this CRF. Subsequently, the licensee corrected the CRF to 0.6 l for unknown bolt type anchors, in accordance with GIP-2 requirements, and reevaluated the seismic adequacy of anchorage for the affected outlier items, which included four heat exchangers. The reevaluation was documented in the BGE response (Reference 6) to questir. No. 6 of the NRC's RAls (Reference 8) and Enclosure C to Reference 6.

In determining the anchorage capacity r;f the subject outlier tanks, BGE took credit for the confining effect of reinforcing bars in floors and/or raised concrete pads for anchor bolts with edge distance or embedment reductions. For instance, the pretreated water storage tank is anchored with 1-3/8-inches cast-in-place J-bolts that are embedded into a 12-inch-wide concrete ring foundation. The bolts have an eoge distance of 3-inches and an embedment of 30-inches. According to GIP-2, Section ll.C.3.4, cast-in-place bolts with an edge distance of 3-in. would have zero shear and pullout capacity. In response to a staff question on this cubject

I 8-during a telephone conference on October 30, 'i998, BGE explained that, on the baris of the presence of a significant amount of reinforcing steelin the ring foundation, which ensured a '

" monolithic" behavior of the concrete ring / slab, failure due to an unreinforced concrete shear

-~ done'was not cred6!elReference 10). On ~the' basis of the review of the reinforcement details presented by BGE in Reference 10, the staff considers BGE's conclusion acceptable for the, A-4o resoluuon. --

The staff finds the licensee's evaluation of the tanks and heat exchangers adequate for the resolution of USl A-46.

2.6 Cable and Conduit Raceways Cable and conduit raceway supports were reviewed in accordance with the requirements of GIP-2, Section 11.8. All raceways that could supply items on the SSEL were reviewed in plant walkdowns. The walkdowns were performed on a room by room basis, and covered the auxiliary building, intake structure, containments, and the turbine building AFW pump rooms.

Cable trays at CCNPP are typically 24-in. X 3-in. metal trays and are generally less than 50 percent full. Most' supports are braced cantilever brackets constructed of back-to-back, two-section struts suspended from overhead embedded struts by two gussetted angle connectors having two bolts per leg. These support strut components were manufactured by Kindorf. The Kindorf strut connections have lower capacities than Unistrut, because the Kindorf strut nuts are not serrated (no teeth are stamped inside the nuts), which makes them outliers in accordance with GlP-2 requirements.

To resolve this generic outlier, ANCO Engineers, Inc. developed a dynamic test program to deter nine the realistic connection capacities of non-serrated strut nuts for cable trays. The test program results were documented in a final report, which was included as Appendix F to the - :ensee's Summary Report (Reference 5). In the ANCO test program, both static and

d. 2mic tests were performed with the non-serrated strut nuts and associated hardware purchased from Kindorf. These tests consisted of direct tension and bending loading conditions. Static tests were also conducted with serrated strut nuts for comparison. Dynamic tests were performed to verify that the strut would not slip out of the connections with non-serrated strut nuts and therefore would maintain the capacity under cyclic loading. The dynamic tests were carried out on full-scale tray system mock-ups using a seismic shake table.

The test results indicated that the strut connections with non-serrated strut nuts did not lose capacity under cyclic loading. A safety factor of 2.0 was also derived from the test results for the realistic capacity of non-serrated strut nuts, and was judged appropriate for use with the GIP-2, Section 11.8, and the procedure for seismic verification. These connection capacities were subsequently used for the three times dead load and lateral load capacity checks in the limited analytical review (LAR) recommended in GlP-2, Section 11.8.3 (Reference 1).

Tweise cable and conduit raceway outliers were identified in Table 7-1 of Reference 5. Six were identified during the in-plant screening walkdown and the other six were identified as a result of the LAR. These outliers were resolved by additional walkdowns, more detailed analyses, or physical modification.

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The staff concludes that the licensee's evaluation of the cable and conduit raceways followed '

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GlP-2 criteria and is acceptable for the resolvhn of USl A-46.

-2.7-Essential Relavs- - - - - - - - - ~ - - - -- --

The Scen: c :tsted that relayspot checks wer,e performed by the seismic review teams during the equipment walkdown and during the separate relay evaluation walkdown. According to the GIP-2 procedure, the purpose of spot checks is to verify the relay mounting, orientation, model number, load path, possioie inimaction, and cable slack. Accordingly, essential relays were checked to confirm that they were mounted as recommended by the manufacturer and to identify any abnormal or atypical relay mounting configurations. Mounting bolts were visually inspected to ensure that the relays were well secured, and relay model, manufacturer, and equipment numbers were checked against the designationt, listed on the electrical schematic drawings. The licensee indicated that no abnormal mountings or damaged relays were founa and that the relay mountings are standard and adequate. The relay types were found to be consistent with identifications shown on electrical drawings.

The licensee indicated that most of the relays affecting safe-shutdown equipment at CCNPP are common types and have moderate-to-high seismic capacity. The cabinets housing the relays are generally standard types. The licensee also indicated that no essential relays were identified as low-ruggedness relays defined in Appendix E to Reference 14. As a result of the relay evaluation, the licensee concluded that all essential relays are seismically adequate.

The staff finds that the licensee's seismic 'elay evaluation is acceptable for the USl A-46 resolution.

2.8 Human Factors Aspect GIP-2 described the use of operator action as a means of accomplishb 1g those activities required to achieve safe shutdown. Section 3.2.7, " Operator Action Permitted," states, in part, that timely operator action is permitted as a means of achieving and maintaining a safe shutdown condition, provided that procedures are available and the operators are trainea in their use. Additionally, Section 3.2.6, " Single Equipment Failure," states that manual operator action of equipment that is normally power operated is permitted as a backup operation, provided 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 that operators should be trained in their use. It is not necessary to develop new orocedures specifically for compliance with the USI A-46 program.

In Section 3.7," Operations Department Review of SSEL," of GIP-2, SQUG also described l three methods for accomplishing the Operations Department reviews o' the SSEL against the l plant operating procedures. Licensees were to decide which method c>r combination of I methods were to be used for t'1eir plant-specific ~eviews. These methods were the following:

l (1) a " desk-top" review of applicable normal and emergency operating procedures, (2) use of a simulator to model the 0xpected transient, x

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(3) performance of a limited control room and localin-plant walkdown of actions required by plant procedures.

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The staff's evaluation of the SQUG approach fdr' identifying and evaluating the SSEL ,

including the use of operator actions, was reported in Section 11.3 of the staff's SSER or . -

- - 1 GlP-2. The staff concluded that the SQUG approach was acceptable.

The staff focussed its review on verifying that the licensee had used one or more of the methods in GIP-2 for conducting the Operations Department review of the SSEL, and had considered aspects of human performance in determining which operator actions could be used to achieve and maintain safe shutdown (e.g., resetting relays, manual operation of plant equipment).

The licensee presented information that outlined the use of the " desk-top" review method by the Operations Department to verify that existing normal, abnormal, and emergency operating procedures were adequate to mitigate the postulated transient and that operators could place the plant in a safe shutdown condition and maintain it in that condition. As part of the desktop review, the licensee evaluated three postulated events: (1) the reactor triis and plant shutdown occur via normal operating procedures, (2) the reactor trips and emergency operating procedures (EOPs) are implemented, and (3) the reactor trips concurrent with loss of offsite power and EGPs are implemented. The licensee stated that, in all cases reviewed the objective was to bring the reactor to hot-shutdown conditions using the equipment available on the SSEL.

The staff verified that the licensee had consioered its operator training programs and had also verified that its training was sufficient to ensure that the operating crews could perform those actions specified in the procedures. 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 required as a l result of the A-46 review. The licensee verified that no new operator actions were required to reset any relays or to restore any system to allow the plant to be brought to a safe-shutdown condition. However, as part of the relay evaluation, the licensee screened out several relay l groups based upon using operator actions. Operator actions might be required in the following areas: resetting battery charger breakers within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, running fire pumps to provide make-up cooling water within a few hours of the event, and restarting a charging pump. In each of these cases, the licensee verified that the required operator actions were within the routine skill of the-craft, and that the time available to accomplish the actions would not place a significant i

additional burden on the operators.

In addition, the staff requested verification that the licensee had adequately evaluated potential challenges to operators, such as lost or diminished lighting, harsh environmental i conditions, potential for damaged equipment interfering with the operators' tasks, and the

, potential for placing an operator in unfamiliar or inhospitable surroundings. The licensee presented information regarding its reviews to substantiate that operator actions cct.:d be accomplished in a time frame required to mitigate the transient. Specifically, the licensee gave 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 Updated Final Safety Evaluation Report, Chapter 14,

" Accident Anmysis for the Loss of Offsite Power (LOOP) Transient," which preceded the A-46 program review. The licensee stated that :,ince these plant procedures had already been validated to ensure that adequate time and resources are available for operators to respond to a LOOP transient, it was not necessary to re-validate these procedures for the USI A-46 prcgram. - -

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The licensee explicitly evaluated the potential for local failure of architectural. features apd the potential for adverse spatialinteractions in the vicinity of safe-shutdown equipment, where'

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local operator action may be required, a3 part of the GIP-2 process. As a result of the review several seismic housekeeping issues affecting the control room were noted and resolved, including strengthening the suspended ceiling and protecting it from collapse, adding a permanent rack for self-contained breathing apparatus, and relocating or removing transitory equipment (e.g., coat racks), which could pose a hazard. The licensee performed seismic interaction reviews, which eliminated any concems with the plant componen'.s and structures located in the immediate vicinity of the components that had to be manipulated. Therefore, the potential for phys' cal 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.

The staff finds that the licensee has provided sufficient information to demonstrate cedermance with the GIP-2 methodology and concludes that its evaluation regarding operator action is acceptable for the USl A-46 resolution.

2.9 Outlier Identification and Resolution The USl A-46 seismic walkdowns identified a total of 266 items as outliers (i.e.,152 for Unit 1 and 114 for Unit 2). As stated by the licensee, roughly 15 percent of the outliers represent

, failure to meet the capacity vs. demand screening criteria,25 percent represent equipment class caveat outliers,35 percent are anchorage outliers, and about 25 percent represent seismic interaction outfiers. Summary listings of all outliers for Units 1 and 2 are in Tables 5.3-1 and 5.3-2, respectively, of the licensee's Summary Report (Reference 5). The tables contain

! a summary description of outlier concems and resolutions.

l A review of Tables 5.3-1 and 5.3-2.Acates that the capacity vs. demand outliers were resolved by either demonstrating compliance with realistic median-centered spectra or by l performing calculations to demonstrate increased capacity. The equipment caveat outliers were resolved by further analysis, maintenance actions, or plant modifications. The anchorage out!iers were resolved by performing bolt tightness checks, further evaluations, and plant modificaticns. The remaining interaction outliers were resolved by modifications, maintenance ntions, and 13e removal of unsecured items from the area containing items on the SSEL.

I in i s response (Reference 6) to an NRC RAI, the licensee clarified the status of the 35 outliers catugorized as unresolved in the Summary Report: two unresolved outliers pertained to cable tray supports have since been resolved by modification; two pertained to non-safety-related components have been resolved by anchorage mooifications; and of the remaining 31 outliers (11 in Unit 1 and 20 in Unit 2),29 had been resolved, as stated by BGE during a telephone conference on October 30,1998, and the final two outliers are related to the control room

l heating. venefion and air-conditioning units, and will be resolved no later than June 30,2001 (Reference 10). - - - -- ~

The stafrs rNew of the licensee's action regarding outliers, indicates that identified' outliers ha've beiniatifactorily resolved or are in the process of being resolved by ana%is or

~~ corrective acSons. The licensee indicated that two remaining outliers have been scheduled to~ ~ -

" be compl@d by June 30,2031. .

.4 3.0

SUMMARY

OF STAFF FINDINGS The stairs review of the licensee's USl A-46 implementation program, as discussed above, did not ident:fy nny significant or programmatic deviation from GIP-2 regarig the walkdown and the seismic ar!aquacy evaluations at CCNPP.

4.0 CONCLUSION

The licenwe's USI A-46 program at CCNPP was established in response to Supplement 1 to GL 87-07 through a 10 CFR 50.54(f) letter. The licensee conducted the USI A-46 implemM Won in accordance with GIP-2. The licensee's submittal on the USl A-46 implemr# don indicated that the SSEL contained 1487 equipment items that were assessed during the m"sdown to verify their seismic adequacy, of which 266 were identified as outliers.

On Octobe 30.1908, the licensee indicated in a teleconference with the NRC that all but two outliers c.em c'esed out. The licensee plans to complete the resolution of the remaining two outliers no !Mer than June 30,2001. The licensee's implementation report did not identify any instance in which the operability of a particular system or component was questionable. As describ ed in Section 3.0, the staff's review did not identify any areas where the licensee's program dMated from GIP-2 and the staff's SSER-2 on SQUG/GlP-2 issued in 1992.

The ste" conc!ades that the licensee's USl A-46 implementation program has, in general, met the purpm ud intent of the criteria in GIP 2 and the staff's SSER-2 for the resolution of USI A-46. The Mr has determined that the licensee's already completed actions will result in safety . Ancements, in certain aspects, that are beyond the original licensing basis.

Accord;n3t y, the Ucensee's actions provide sufficient basis to close the USl A-46 review at the facility. Tha staff a!so concludes that the licensee's implementation program to resolve USI A-46 at iM fo@y has adequately addressed the purpose of the 10 CFR 50.54(f) request.

License -W: ties re!ated to the US! A-46 implementation may be sutyect to NRC inspection.

Regardd future use of GIP-2 in licensed activities, the licensee may revise its licensing basis in accoc'm with the guidance in Section 1.2.3 of the staff's SSER-2 on SQUG/ GIP-2 (Referen e ?) and the staff's letter to SQUG's Chairman, Mr. Neil Smith, on June 19,1998 (Refe, ente 15). Where plants have made specific commitments in the licensing basis with respect to seismic qualification, those commitments should be carefully considered. The overa': emuMWe effect of the incorporation of the GIP-2 methodology, considered as a whole, st 7.1 Le assessed in making a determination under 10 CFR 50.59. An overall conclu m that no USQ !s involved is acceptable as long as any changes in specific l

commitments in the licensing basis have been thoroughly evaluated in reaching the overal!

conclus;on. if the overall cumulative assessment leads a licensee to conclude a USQ is

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involved , incorporation of the GlP-2 methodology into the licensing basis would require the

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j licensee to seek an ame'ndmerit according to the provisions of 10 CFR 50.90. ,

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Principal Contributors: C.Wu - ~ --

-- K: Desal n -

R. Pichumani )

G. Galletti - - - -

- l Date: January 20, 1999 l

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5.0 REFERENCE.S

1. Seismic Qualification Utility Group, " Generic Implementation Procedure (GIP) for Seismic Verification of Nuclear Power Plant Equipment," Revision 2, corrected February 14,1992 ~

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~270.S. NRC?SuppTem~erildFSifely Faltistion Report No. 2 on Seismic Qualification Utility ,

Group's Generic implementation Procedure, Revision 2, corrected February 14,1992." '

iviay ;u; 1W2 -

l 3. Baltimore Gas and Electric Company (BGE) letter to U.S. NRC Document Control Desk,

" Response to Generic Letter 87-02 Supplement Nu.1 on Seismic Qualification Utility ,

Group (SQUG) Resolution of USl A-46, Calvert Cliffs Nuciec- Power Plant Units 1 and 2,"

September 18,1992 i; l

l 4. U.S. NRC letter to BGE, " Safety Evaluation Regarding September 18,1992 Response to l l Supplement No.1 to Generic Letter 87-02, Calvert Cliffs Nuclear Power Plant Units 1 and 2," November 20,1992

5. BGE letter to U.S. NRC Document Control Desk, " Generic Letter 87-02, Summary Report for Resolution of USI A-46," June 28,1996, and Attachment 1, "Calvert Cliffs Nuclear Power Plant Units 1 and 2, USl A-46 Seismic Evaluation Report - May 1996*

{ I i 6. BGE letter to U.S. NRC Document Control Desk, " Response to Request for Additional  !

l Information on the Resolution of USl A-46, Calvert Cliffs Nuclear Power Plant 1 Units 1 and 2," March 23,1998

7. BGE letter to U.S. NRC Document Control Desk," Response to Request for Additional l

Information on the Resolution of USI A-46, Calvert Cliffs Nuclear Power Plant

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Units 1 and 2," September 22,1998 ,

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8. U.S. NRC letter to BGE, " Request for Additional Information on the Resolution of USl A-46, Calvert Cliffs Nuclear Power Plant Units 1 and 2 (TAC Nos. M69435 and M69436),"

l December 19,1997 l

9. USNRC letter to BGE," Request for AdditionalInformation on the Resolution of USl A-46, Calvert Cliffs Nuclear Power Plant Units 1 and 2 (TAC Nos. M69435 and M69436) " March 2,1998

10. BGE letter to U.S. NRC Document Control Desk, "Calvert Cliffs Nuclear Power Plant Units 1 and 2, Response to Request for AdditionalInformation on Resolution of USI A-46 (TAC Nos. MG9435; MS9436)," November 12,1998. A follow-up to a telephone conference bet".een BGE engineers and the NRC staff, which was held on October 30, 1998

! 11. BGE,"Calvert Cliffs Nuclear Power Plant Units 1 and 2, USl A-46 Relay Evaluation i Report," MPR-1371, Revision 1, November 1995 (Attachment 2 to the CCNPP summary report for USI A-46 resolution (Reference 5))

12. U.S. NRC NUREG/CR-0098," Development of Criteria for Seismic Review of Selected l Nuclear Power Plants," May 1978

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13. Electric Power Researchin~stitute (EPRI) NP-5223-SL, " Guidelines on Tanks and Exchangers," Revision 1, Volume 4, June 1991 . ,. .__

14. EPRI NP-7148-SL," Procedure f or Evaluating Nuclear Power Plant Relay Seismic t-Linctio~nality,"yeeimb~er 1990. , ,

15. i.wiiw hom Brian W. Short5n to Neil Smith, dated June 19,1998

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