ML20236X532

Safety Evaluation Re USI A-46 Program Implementation for Plant

ML20236X532
Person / Time
Site:	Duane Arnold
Issue date:	07/29/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20236X520	List: ML20236X518 ML20236X532
References
REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR NUDOCS 9808100071
Download: ML20236X532 (12)

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UNITED STATES j

NUCLEAR REGULATORY COMMISSION 4

WASHINGTON, D.C. 20066-0001

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ON UNRESOLVED SAFETY ISSUE A-46 PROGRAM IMPLEMENTATION lES UTILITIES INC.

CENTRAL IOWA POWER COOPERATIVE

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1 CORN BELT POWER COOPERATIVE DUANE ARNOLD ENERGY CENTER DOCKET NO. 50-331

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 generic letter, the NRC staff set forth the process for resolution of USl A-46, and encouraged the affected nuclear power plant licensees to participate in a generic program to resolve the seismic verification issues associated with USl A-46. As a result, the Seismic Qualification Utility Group (SQUG) developed the " Generic Implementation Procedure (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 including 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 provide either (1) a commitment to use both the SQUG commitments and the implementation guidance described in GlP-2, as supplemented by the staff's SSER-2, or (2) an alternative method for responding to GL 87-02. The supplement also required that those addressees committing to implement GIP-2 provide an 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 21,1992 (Reference 3), IES Utilities Inc. (lES), the licensee, provided its response to Supplement 1 to GL 87-02 for the Duane Amold Energy Center (DAEC). In the letter, IES committed to follow the SQUG commitments set forth in GIP-2, including the clarifications, interpretations, and exceptions identified in SSER-2. The staff issued its evaluation of the licerdee's response by letter dated November 25,1992 (Reference 4).

By letter dated November 15,1995 (Reference 5), as supplemented on December 11,1995 (Reference 6), and July 15,1998 (Reference 16), IES submitted a summary report containing the results of the USl A-46 program implementation at DAEC. By letters dated August 30,1996 (Reference 7), December 20,1996 (Reference 8), July 2,199i (Reference 9), and January 16, 9808100071 900729 PDR ADOCK 05000331 P

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2 1998 (Reference 10), !ES provided supplemental information and clarification in response to the staffs requests for additional information (RAls), dated July 3,1996 (Reference 11), October 21,1996 (Reference 12), February 25,1997 (Reference 13), and November 18,1997 (Reference 14), respectively.

This report provides the staffs evaluation of the licensee's USl A-46 implementation program.

The evaluation is based on the staffs review c4 the summary report and of the supplemental information, clarification, and documentation provided by the licensee in response to the staffs RAls.

2.0 DISCUSSION AND EVALUATION The summary report (Reference 5) provides the licensee's implementation results of the USI A-46 program at DAEC. The report gives a safe shutdown equipment list (SSEL) and documents the screening verification and walkdown of mechanical and electrical equipment and the relay evaluation. The report also documents the evaluation of seismic adequacy for tanks, heat exchangers, and cable and conduit raceways, identifies outliers, and proposes resolutions including projected schedules.

2.1 Seismic Demand Determination (Ground.Soectra and in-structure Resoonse Soectra)

The licensee utilized the licensing-basis design response spectra (DRS), as defined in Section 2.5.2.6 of the DAEC Updated Final Safety Analysis Report (UFSAR), as the seismic input at grade level to develop the in-structure response spectra (IRS) at floor elevations in the Reactor Building (RB), Control Building (CB), Pump House (PH), Intake Structure (IS), and Turbine Building (TB). The Safe Shutdown Earthquake (SSE) DRS horizontal components have a peak ground acceleration (PGA) of 0.12g, excapt for structures supported on 30 to 50 feet of soil over the bedrock. For these structures, the PGA is 0.18g. The corresponding vertical PGAs are 0.08g and 0.12g, respectively. The method of developing the IRS had been evaluated by the staff and found acceptable (Reference 4).

2.2 Seismic Evaluation Personnel The DAEC seismic evaluation was conducted by a multi-disciplined project team. The team included both IES Utili+.ies and contractor employees. The seismic capability engineers (SC'is) for the DAEC walkdown consisted of two engineers from MPR Associates, Inc., and seven engineers from EQE Engineering Consultants, Inc., identified in Section 3 of Reference 5. The resumes of the SCEs are provided in Appendix A of Reference 5. The IES engineers, who were familiar with the structural, mechanical systems, and electrical and condof systems, provided the plant-specific information to the SCEs and performed in-process reviews of contractor activities throughout the course of the USl A-46 program.

The licensee stated that the systems engineers identified the safe-shutdown paths and prepared the draft GSEL. The SSEL items were then reviewed by the Operations Department personnel at DAEC. The electrical engineers prepared a list of the relays associated with items i

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. of the SSEL. The licansee indicated that the DAEC operations engineers had also reviewed the SSEL for compatibility with the plant operating procedure used to shut down the plant and maintain it in a safe-shutdown condition for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

The staff finds that the SCE's qualifications fully satisfy the provisions of GIP-2. The staff also notes that the " third party" reviewer and the SCEs are widely recognized for their experience in the field of seismic evaluation of structures, systems, and components.

2.3 Safe-Shutdown Path GL 87-02 specifies that the licensee should be able to bring the plant to, and maintain in, a hot shutdown condition during the first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following an SSE. To meet this provision, in its submittal of November 15,1995, the licensee addressed the following plant safety functions:

reactor reactivity control, prc:sure control, inventory control, and decay heat 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 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 C of Reference 5 provides the safe-shutdown equipment list.

. The reactor decay heat removal function is accomplished by releasing steam from the reactor via the safety / relief valves into the torus. The reactor coolant system (RCS) inventory is controlled by niecting water into the RCS. This is done by the low pressure coolant injection (LPCI) mode of the residual heat removal (RHR) system which takes suction from the torus.

The torus water is pumped through the RHR haat exchangers before being injected into the RCS. The core spray system is available as an attemate safe-shutdown success path to makeup inventory to the RCS. The RHR system is also used to cool the water in the torus.

The suppression pool cooling (SPC) mode of the RHR system circulates water from the torus through the RHR heat exchangers and back to the torus. The RHR heat exchangers transfer the decay heat from the torus to the RHR service water system.

The plant Operations Department reviewed the safe-shutdown success paths and concluded that the plant operating procedures and operator training were adequate to establish and maintain the plant in a safe-shutdown condition using the equipment identified in Appendix C of Reference 5.

The staff concludes that the licensee's approach to achieve and maintain safe-shutdown for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after a seismic event is ecceptable.

2.4 Seismic Screenina Verification and Walkdown of Mechanical and Electrical Eauipment The seismic screening and walkdown included verification of 620 equipment items which are typical of those found in the SQUG experience database in the 20 classes of equipment covered in Appendix B of GIP-2 (Reference 1). The tanks and haat exchangers are evaluated in Section 2.5 of this SE.

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2.4.1 Eauioment Seismic Caoacity Comoared to Seismic Demand The seismic capacity of equipment classes covered in GIP-2 (Reference 1) was used by the licensee for determination of the seismic adequacy and compared with either the ground resporise spectra (GRS) or the IRS as recommended by GIP-2. The capacity spectra are provided in GIP-2 as the bounding spectra (BS), amplified bounding spectra (ABS = 1.5XBS) or generic equipnent rugged spectra (GERS).

The licensee indicated that the DAEC GRS are enveloped by the GIP-2 BS for all frequencies.

A comparison of the DAEC 1RS with the ABS is summarized in Table 5-2 of Reference 5. This table provides the buildings and elevations where the IRS exceeds the ABS over specific frequency ranges for the floors containing SSEL equipment. The licensee stated that the IRS for the reactor building are fully enveloped by the ABS for elevations containing SSEL equipment. However, in other structures, the IRS exceed the ABS at some frequency ranges.

In response to the staff's questions on the use of Method A of Table 4.1 in GIP-2 for comparing the seismic capacity of the equipment (represented by the GIP-2 bounding spectrum), the licensee responded (in References 7 and 9) that in general, it has used Method A for equipment located within 40 feet above the effective grade of the building and for equipment frequencies higher than 8 Hz. The effective grade elevations for the five DAEC structures that contain SSEL equipment are summarized in Table 5-3 of Reference 5. However, recognizing the staff's concern regarding the use of this method where the corresponding IRS exceeds 1.5 times the GIP-2 bounding spectrum, the licensee noted in its response dated July 2,1997 (Reference 9), to the staff's RAI dated February 25,1997 (Reference 13), that the IRS was always used for quantitative evaluations, and it has evaluated the relevant equipment using Method B of Table 4-1 in GlP-2.

In its January 16,1998 letter (Reference 10), the licensee indicated that of the 620 SSEL items walked down and evaluated during the USI A-46 review,336 items were evaluated for capacity versus demand. Of the 336 items,237 are located at elevations at which the IRS is enveloped by the ABS,56 are located at elevations where the IRS exceeds the ABS for frequencies less than 8 Hz. Other 43 items located at elevations where the IRS exceed the ABS at frequencies above 8 Hz are listed in Table 1 of Reference 10.

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For a majority of SSEL equipment items that are located on floors where the IRS is not J

enveloped by the ABS, the licensee verified their frequencies to be greater than the frequency ranges where the IRS exceed the ABS. These components were then screened using the GIP-2 ABS vs. the IRS. For instance, for the cor,trai building elevations 786' and 800* where the IRS are bounded by the ABS except for fre.;uencies below 4 Hz, the SSEL equipment items such as cabinets, dampers, fans and temperature elements were verified to have frequencies above 8 Hz and, therefore, were screened using the ABS vs. the IRS. Screening was also done using BS vs. GRS for equipment, with fr equencies above 8 Hz, located within 40' above the grade level. The IRS for the intake StructJre elevations 754' and 767' exceed the ABS for frequencies between 8 Hz and 25 Hz. Dampers and vent fanc in the intake Structure were judge i to have frequencies in the rigid rsage, and were screened by the licensee using BS vs.

GRS. The IRS for the Pump House are bounded by the ABS except for frequencies below 5 Hz. Four RHR service water pump 5 in the Pump House have frequencies of at least 8 Hz l

based on the existing analysis, and were screened using BS vs. GRS.

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For some equipment items whose frequencies are not higher than those of the frequency ranges where the IRS exceed the ABS, the licensee evaluated their seismic adequacy using GERS or equipment capacities based on the existing seismic qualification documentation. As such, the licensee verified the seismic adequacy for a low voltage switchgear and some MCCs in the intake Structure using GERS vs. the IRS. Two large air handlers in the control building were mounted on a spring-type vibration isolator and were estimated to have frequency near 4 Hz. The seismic capacity for these air handlers obtained from the existing seismic qualification documentation was used to meet the IRS demand. Two emergency service pumps were estimated to have frequencies below 5 Hz where the IRS are higher than the ABS.

These pumps were screened by the licensee to ensure that their actual seismic capacities (from the existing documentation) are higher than the IRS demand.

The licensee has followed the GIP procedures for comparing equipment seismic capacity to seismic demand, and the staff considers the evaluation to be adequate for the resolution of USI A-46.

2.4.2 Assessment of Eauioment " Caveats" The licensee indicated in Reference 5 that the SCEs verified that the caveats listed in Appendix B of the GIP-2 ior each equipment class were met for DAEC. 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 meet the specific wording H certain caveats but is deemed seismically adequate based on the judgment of the SCE.

The results for equipment whose seismic adeques,..as verified by meeting the caveats were documented in Appendix D of Reference 5. In many cases, items of equipment which did n >t meet the GIP-2 caveats were considered as outliers and were documented in Section 6 of the DAEC summary report for USl A-46 resolution in some cases,if an item of equipment was judged to meet the intent of the caveats, but the specific wording of the caveat rule was not met, then the equipment 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 Section 5 of Reference 5.

In its response of August 30,1996 (Reference 7), to the staff's RAI dated July 3,1996 (Reference 11), the licensee provided supplemental information, for some equipment items, to demonstrate how the intent rather than the wording of certain caveats was met. For instance, additional information was provided for diaphragm-operated pneumatic valves CV6116A and B whose yokes are made of cast iron. This violates Bounding Spectrum Caveat No. 3 for fluid-operated valves of class 7 equipment as delineated by GIP-2. The licensee indicated that the reviewing SCEs performed an evaluation and calculated the stresses for a 3g stath: load in the valve yoke wouest direction. The calculated yoke stress was approximately 5 ksi (or 17 l

percent of the minimum tensile strength of 30 ksi for the yoke material), which is considered low l

and meets the intent of the caveat in accordance with GIP-2.

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l The licensee indicated that these diaphragm-operated pneumatic valves, CV6116A and B, were initially identified by the DAEC SCEs as meeting the intent but not the letter of Bounding Spectrum Caveat No. 3 for fluid-operated valves. During the third party review, these two valves were determined to have met sii caveats for class 7 equipment as delineated by the j

GIP-2 and were removed from Tsole 5-4 in the final version of the summary report.

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

2.4.3 Eauioment Anchoraae The anchors used at DAEC are predominantly Phillips Redhead expansion anchors, cast-in-place headed studs, embedded plates, and cast-in-place J-bolts. In Reference 5, the licensee stated that both the field inspections and analytical calculations were performed to verify the adequacy of equipment anchorages. Field insC:ns included anchor tightness checks in acccrdance with the provisions of GIP-2 Se won 11.4.4.1 and Appendix C concerning concrete expansion anchors. All equipment anchorap installations, except a few nonstandard and J-bolt installations, were verified for the 3eisme loading and found to be acceptable. The nonstandard installations and J-bolt installations were identified as out!iers.

Table 8-1 (Reference 5) shows 10 J-bolt installations and 14 nonstandard or inadequate anchorage installations. The nonstandard and inadequate installations were resolved by analysis and/or hardware modifications. The J-bolt installations were verified by calculations.

In its response (Reference 7) to the staff's RAI (Reference 11), the licensee provided a set of calculations for the seismic adequacy of the J-bolt anchorages for the residual heat removal service water pumps (the worst-case loading for equipment with J bolt anchorage installation).

The staff review of the calculations indicated that the licensee's consultant (MPR Associates) had used the strength reduction factors of 0.46 (for tension) anc' U.25 (for shear) in calculating the allowable loads to account for inadequate embedment length and edge distance. With these reduction factors, and using the gip-2 (Appendix C) interaction curves, the licensee l

demonstrated that the J-bolt installation was adequate for the seismic loading. Based on this I

review, the staff finds the licensee's evaluation of equipment anchorages acceptable for USl I

A-46 resolution.

2.4.4 Seismic Sostial interaction Evaluation The licensee stated in its summary report (Reference 5) that several seismic interaction conditions were identified during the walkdown. The identified conditions involve overhead i

fluorescent light fixtures, wall-mounted emergency lights, portable scaffolding, portable fire extinguishers, unbolted adjacent cabinets, unsecured low-voltage switchgears, a loose steel beam in the ceiling, steel members hung above the main steam isolation valve (MSIV), portable equipment items (bookcases, storage cabinets, equipment carts, etc.), and the Control Room ceiling. These conditions were identified as outliers. Forty-three interaction outliers are identified in Table 8-1 of Reference 5. These identified outliers were resolved either during the plant walkdown or later by analyses and/or physical modifications.

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The DAEC Seismic Review Team (SRT) also indicated that all block walls that could potentia'ly affect the SSEL equipment were checked to confirm that they are seismically adequate under DAEC'sBulletin 80-11 program. For example, a masonry block wall above a pump in the southeast corner room was found to have a potential for falling on the pump, and not to be qualified for seismic adequacy by the provisions of NRC Bulletin 80-11. The licensee's consultant analyzed the wall and found that it met the provisions of the bulletin. In another interaction item, a structural steel member above a valve in the steam tunnel could damage the valve during the postulated SSE. The member was removed to eliminate such a possibility.

I Therefore, the staff finds the licensee's seismic spatial interaction evaluation acceptable for the resolution of USl A-46, 2.5 Tanks and Heat Exchanaars The DAEC SSEL includes 30 tanks and 6 heat exchangers. The DAEC SSEL does not contain

. any f!st-bottom vertical tank. The majority of the tanks are air receivers or accumulators and nitrogen accumulators. All horizontal tanks and heat exchangers meet the seismic adequacy criteria of Chapter 7 of GIP-2. The small vertical tanks supported by structural steellegs were evaluated for the applicable seismic loads and found to be acceptable. The only outliers associated with the tanks were (1) an MSIV accumulator which could be potentially impacted by the adjoining unrestrained ladders and rolling carts, and (2) a 40,000 gallon diesel oil tank

- buried in the protected yard outside the Turbine Building. To resolve the first outlier, the licensee removed the potentially damaging items from the area.

In its response (in Reference 7) to the staff's RAI (in Reference 11) regarding the design and condition of the buried diesel oil tank, the licensee provided a copy of the ohginal tank specifications and design calculations, and the relevant Screening Evaluation Work Sheets (SEWSs), and the Outlier Seismic Verification Sheet (OSVS) (Reference 7, Addenda 4 and 5).

A review of the calculations indicated that the stresses in the tank plates under the SGE loading were well below the allowable. A review of the field conditions observed by the SCE and his evalua;lon indicated that the horizontal tank was well supported by the surrounding earth and that the attached piping was flexible. In response to the question on the SCE's judgment regarding the present surface condition of the tank and settlement of the tank, the licensee -

stated the following SCEs judgment (Reference 9):

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The external surface of the tank is coated with one coat of anti-corrosive Bituministic Black solution; b.

The tank and its associated piping are well supported by the soil; c.

The existing / observed flexibility in the piping and electrical conduit is adequate; d.

For the SSE, the soil failure is not credible; therefore, significant differential motion between the piping and the tank is not possible.

Based on the information provided by the licensee in References 5, 7, and 9 regarding the l

seismic adequacy cf the tanks and heat exchangers included in the SSEL, the staff finds that I

the tanks and heat exchsngers are seismically adequate for the resolution of USl A-46, f

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8-2.6 Cable and Conduit Raceways in Section 7 of Reference 5, the licensee describes efforts to review the seismic adequacy of the cable and conduit raceway supports. The licensee stated that all raceways which support electrical wires for the SSEL were reviewed. These reviews were conducted on an area-by-area basis, and include areas that could contain divisional (Class 1E) cables. The licensee indicated that the plant areas were chosen to coincide with logical breaks in the building geometry, such as enclosed rooms, corridors, etc. The licensee also indicated that the walkdown evaluations covered a total of 34 designated areas wiMin the RB, CB, TB, IS, and PH.

Additionally, as recommended by GIP-2, the licensee selected 15 supports, judged by the SCE to be the worst case supports, for a limited analytical review (LAR). To understand the general methodology used by the licensee to demonstrate the seismic adequacy of the selected supports, the staff requested the licensee to provide the SEWS, the OSVS, and the related calculations (Reference 7) for two supports which were identified as outliers during the LAR.

The staff review of the information pnvided by the licensee, in general, indicated that consistent procedures (in accordance with GIP-2) had been used in identifying the outliers, resolving the outliers either by outlier-specific analysis (i.e., considering the actual loads and computing the margins) or by corrective actions. In response to tne staff's question on the assumption of ductile supports, the licensee listed the assurned " ductile" supports in the LAR and provided the following justification (Reference 10): of 15 supports selected in the LAR,6 supports were considered ductile. Of these six supports, two supports were judged ductile, but the licensee performed the lateralload checks to ensure their saismic adequacy. The sketches of the remaining four supports met the basic characteristics of ductile supports as described in GIP-2.

Based on the review of the licensee's submittals (References 5,7,9, and 10), the staff concludes that the licensee has followed GIP-2 guidelines ir assessing the seismic adequacy of the cable tray and conduit raceway supports. Therefore, the staff considers the cable tray and conduit raceway suppoits seismically adequate for the re,olution of USl A-46.

2.7 Essential Relays The licensee stated that relay spot checks were perfonned by the seismic review teams during the equipment walkdown and during the separate relay cycluation walkdown. According to the GIP-2 procedure, the purpose of spot checks is to verify the relay mounting, orientation, model number, load path, possible interaction, and cable slack. Accordingly, essential relays were checked to confirm that they were mounted in accordance with manufacturer recommendations 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 designations listed on the electrical schematic drawings. The licensee indicated that no unuMal findings were noted during the walkdowns, other than a minor mounting deficiency involving a few missing or loose mounting screws.

Appendix D of the USI A-46 reis.y evaluation report (Reference 15) identifies 34 outlier essential i

relays (located in essential switchgears 1 A3 and 1 A4), of which 28 were reassessed to be

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seismically adequate. These 28 devices are highlighted in Table D-1 with a footnote. Of the remaining six outliers, two were GE HFA151 essential relays with a seismic demand that exceeds their ccpacity, and four were essential relays for which seismic capacity data was unavailable. The licensee resolved these remaining outliers during Refueling Outage 15, as reported in its "NG-98-1221, Forwards Monthly Operating Rept for June 1998 for Daec,Per GL 97-02.Revised Contents of Monthly Operating Rept & Distribution Made IAW DAEC [[TS" contains a listed "[" character as part of the property label and has therefore been classified as invalid..c|July 15,1998 letter]] (Reference 16).

In addition to the ou1liers discussed above, five SSEL equipment items listed in Table 6-3 of Reference 15 (three Battery Room exhaust fans and two Control Building chillers) were screened out using ~ 0perator actions." An overall assessment of areas involving operator action is included in Section 2.8 below.

The staff finds the licensee's seismic relay evaluation to be acceptable for the USl A-46 resolution.

2.8 Human Factors Asoect The licensee provided information which outlined the use of the " desk-top" evaluation method by a senior licensed operator to verify that existing normal, abnormal, and emergency operating procedures were adequate to mitigate the postulated transient and that operators could place and maintain the plant in a safe-shutdown condition. The staff verified that the licensee had considered its operator training programs and verified that the training was sufficient to ensure that those actions specified in the procedures could be accomplished by the operating crews.

The licensee stated that the shutdown path selected for USI A-46 and included in the SSEL was a legitimate safe-shutdown path consistent with DAEC procedures and operator training.

The present level of operator training assures that the operators are sufficiently proficient in the procedures to use the correct success path.

In addition, the staff requested verification that the licensee had adequately evaluated potential challenges to operators, ruch as lost or diminished lighting, harsh environmental conditions, i

damaged equipment, and unfamiliar or inhospitable surroundings. The licensee provided information regarding its evaluations to substantiate that operator's actions could be j

accomplished in time to mitigate the transient. Specifically, the licensee provided assurance that ample time existed for operators to take the required actions to safely shut down the plant.

The licensee verified that existing procedures, availability of lighting equipment, and operator training were adequate to ensure the operators could perform the required actions credited in the submittal. The licensee verified that all required actions were grouped in Seismic Category 1 structures, which are easily accessible and familiar areas of the plant (i.e., the Control and Reactor Buildings). The licensee performed seismic interaction reviews and eliminated any concerns 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 is not considered to be a significant hazard. The licensee has provided the staff with sufficient information to demonstrate conformance with the NRC-approved review i

methodology outlined in GIP-2..

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. o On the basis of its review of the licensee's information, the staff finds that the licensee has adequately substantiated that operator's actions could be accomplished in time to mitigate the l

seismic event.

I 2.9 Outlier identification and Resolutions Section 8 of Reference 5 documents the equipment outliers identified during the USI A-46 implementation effort at DAEC. The documentation also in;ludes descriptions of the i

associated defects or inadequacies, methods for resolving outliers, and the dates the outliers were resolved or proposed to be resolved when the USl A-46 program implementation submittal was made, i

items of equipment were identified as outliers for three reasons: equipment class caveats, I

anchorage adequacy, and seismic interactions. The significant outliers associated with anchorages, tanks and heat exchangers, and cable tray and conduit raceway supports are discussed in Sections 2.4.3,2.S. and 2.6 of this SE. The staff review of the licensee's resolution of outliers indicated that all outliers had been resolved by either analysis or corrective

' actions.

3.0

SUMMARY

OF STAFF FINDINGS The stafs review of the licensee's USI A-46 implementation program, as discussed above, did not find any significant or programmatic deviation from GP-2 regarding the walkdown and the seismic adequacy evaluations at DAEC.

4.0 CONCLUSION

The licensee's USl A-46 program at DAEC was established in response to Supplement 1 to GL 87-02 through a 10 CFR 50.54(f) letter. The licensee conducted the USl A-46 implementation in accordance with GlP-2. The licensee's submittal on the USl A-46 implementation indicated that the safe-shutdown equipment list contained 1433 components, of which 620 were walked down to verify their seismic adequacy. A total of 104 equipment items and 34 essential relays were identified as out!iers. By "NG-98-1221, Forwards Monthly Operating Rept for June 1998 for Daec,Per GL 97-02.Revised Contents of Monthly Operating Rept & Distribution Made IAW DAEC [[TS" contains a listed "[" character as part of the property label and has therefore been classified as invalid..c|letter dated July 15,1998]] (Reference 16), the licensee reported the resolution of all remaining outliers. The licensee's implementation report did not identify any instance where the operability of a particular system or component v:as questionable. As described in Section 3.0, the stafs review did not identify any areas where the licensee's program deviated from GIP-2 and the stars SSER No. 2 on SQUG/ GIP-2 issued in 1992.

The staff concludes that the licensee's USl A-46 implementation program has, in general, met the purpose and intent of the criteria in GlP-2 and the stafs SSER No. 2 for the resolution of USl A-46. The staff has determined that the licensee's already completed actions will result in safety enhancements, in certain aspects, that are beyond the original licensing basis.

Accordingly, the licensee's actions provide sufficient basis to cicsa the USl A-46 review at the facility. The staff also concludes that the licensee's implementation program to resolve UGl A-46 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.

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Regarding future use of GIP-2 in licensed 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, (Reference 2) and the staff's letter to SQUG's Chairman, Mr. Neil Smith on June 19,1998.

Where plants have specific commitments in the licensing basis with respect to seismic 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 unreviewed safety question (USQ) is involved is acceptable so long as any changes in specific commitments in the licensing basis have been thoroughly evaluated in reaching the overall conclusion.- If the overall cumulative assessment leads a licensee to conclude a USQ is involved, incorporation of the GIP-2 methodology into the licensing basis would require the licensee to seek an amendment under the provisions of 10 CFR 50.90.

Principal Contributors: C. Wu H. Ashar K.Desai G. Galletti Date:

July 29, 1998

5.0 REFERENCES

1.

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

2.

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

3.

IES Utilities letter, to NRC Document Control Desk, " Response to Supple & nt 1 to j

Generic Letter 87-02, SQUG Resolution of USl A-46," dated September 21,1992.

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4.

R. Pulsifer (NRC) letter, to L. Liu (lES Utilities, Inc.), "Evahation of Duarie Amold Energy Center (DAEC),120-Day Response to Supplement No.1 to Generic Letter 87-02" (TAC No, M69444), November 25,1992.

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5.

John Franz (lES) letter, to William T. Russell (NRC), " Generic Letter 87-02, Summary Report for Resolution of USl A-46," November 15,1995, and Attachrnent 1,"Duane Amold Energy Center USl A-46 Seismic Evaluation Report."

6.

John Fran2 (lES) letter, to William T. Russell (NRC), " Generic Letter 87-02, Summary Report for Resolution of USl A-46 " December 11,1995,. and Attachment 1, "Duane Amold Energy Center USI A-46 Seismic Evsluation Report."

l 7.

John Franz (lES) letter, to NRC, "Respense to NRC's Request for Additional Information on the Resolution of USI A DAEC," August 30,1996.

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• 8.

John Franz (lES) letter, to NRC. " Response to NRC's Request for Additional Information on the Resolution of USl A DAEC," December 20,1996.

9.

John Franz (lES) letter, to NRC, " Response to NRC's Request for Additional Information on the Resolution of USl A DAEC," July 2,1997.

10.

John Franz (lES) letter, to NRC, " Response to NRC's Request for Additional Information on the Resolution of USl A DAEC," January 16,1998.

11.

G. Kelly (NRC) letter, to L. Liu (lES), " Request for Additional Information Resolution of USl A-46," July 3,1996.

12.

G. Kelly (NRC) letter, to L. Liu (lES), " Request for Additional Information Resolution of USI A-46," October 2!,1996.

13.

G. Kelly (NRC) letter, to L. Liu (lES), " Request for Additional Information Resolution of USI A-46," February 25,1997.

14.

G. Kelly (NRC) letter, to L. Liu (lES), " Request for Additional Information Resolution of USl A-46," November 18,1997.

15.

MPR Associates, Inc.,"Duane Arnold Energy Center USI A-46 Relay Eva!uation Report," MPR-1545, Revision 0, Seotember,1995 (Attachment 2 to the IES summarv report for USI A-46 resolution).

16.

K. Peveler (lES) letter, to NRC, "USI A-46 Evaluation," July 15,1998.

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