ML18106A312

Forwards Response to 970404 RAI Re Resolution of USI A-46, Seismic Qualification of Equipment in Operating Plants. Outlier Resolution Schedule Is Being Revised Since Implementation Issues May Affect Number of Outliers

ML18106A312
Person / Time
Site:	Salem
Issue date:	02/13/1998
From:	Eric Simpson Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR LR-N970770, NUDOCS 9802230187
Download: ML18106A312 (13)

Text

• ii Public Service Electric and Gas Company FEB 1 3 1998 E. C. Simpson Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-1700 Senior Vice President

-Nuclear Engineering United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 LR-N970770 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION UNRESOLVED SAFETY ISSUE A-46 SEISMIC QUALIFICATION OF MECHANICAL AND ELECTRICAL EQUIPMENT IN OPERA TING PLANTS SALEM GENERATING STATION UNITS 1 AND 2 DOCKET NOS. 50-272 AND 50-311 Ladies and Gentlemen:

Public Service Electric and Gas (PSE&G) is providing a response to the NRC request for additional information dated April 4, 1997. This additional information pertains to the resolution of USI A-46, "Seismic Qualification of Equipment in Operating Plants." In letter dated May 22, 1995 (LR-N95073) and March 29, 1996 (LR-N96083), PSE&G* committed to evaluate equipment outliers (as defined in the A-46 program) and make appropriate hardware modifications where required by the end of the Salem Unit 1 1R14 refueling outage and Salem Unit 2 2R10 refueling outage. As described in the enclosed NRC staff questions; there is continuing dialog between the Seismic Qualification Utility Group and the NRC staff regarding implementation issues which may affect the number of outliers.

Therefore PSE&G is revising its outlier resolution schedule.

PSE&G will disposition.all outliers before the end of the second refueling outage following receipt of the Salem specific Safety Evaluation Report (SER) that approves the use of GIP-2 methodology for resolution of the USI A-46. program. If you have any questions regarding this information we will be pleased to discuss them with you. Affidavit Attachment (1)

• Figures (2) * ----------* --------. --------, 9802230187 980213 PDR ADOCK 05000272 p PDR Printedon

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Document Control Desk

• C Mr. H. Miller, Administrator

-Region I U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 2 Mr. P. Milano, Licensing Project Manager -Salem U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 14E21 Rockville, MD 20852 Ms. M. Evans (X24) USNRC Senior Resident Inspector Salem Generating Station Mr. K. Tosch, Manager, IV Bureau of Nuclear Engineering POBox415 Trenton, NJ 08625 F'EB. 7999 95-4933 Document Control Desk MKG/tcp

• 3 BC Senior Vice President

-Nuclear Engineering (N19) Senior Vice President

-Nuclear Operations (X04) General Manager -Salem Operations (SOS) Director -QA/NT/EP (X01) Director -Design Engineering (N25) Manager -Financial Control & Co-Owner Affairs (NO?) Design Specialty Manager (N51) T. Taylor (N10) G. Luh (N51) J. Keenan, Esq., (N21) Records Management (N21) Microfilm Copy File Nos. 1.2.1, 3.5 (GL 87-02), 5.6

• REF: LR-N970770 STATE OF NEW JERSEY SS. COUNTY OF SALEM E. C. Simpson, being duly sworn according to law deposes and says: I am Senior Vice President

-Nuclear Engineering of Public Service Electric and Gas Company, and as such, I find the matters set forth in the above referenced letter, concerning the Salem Generating Station, Unit Nos. 1 and 2, are true to the best of my knowledge, information and belief. KIMBEnl Y JO BROWN NOTARY_

OF NEW JERSEY expires on ___

......

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• *

Introduction:

The following references are made in the NRC Requests for Additional Information (RAI): 1. Licensee Submittal to NRC Document Control Desk "Generic Letter 87-02 and Supplement 1, USI A-46 Walkdown Summary Report, Salem Generating Station Unit Nos. 1 and 2," May 22, 1995. 2. Letter from NRC to Public Service Electric and Gas Company "Request for Additional Information on the Resolution of Unresolved Safety Issue A-46, Salem Generating Station Unit Nos. 1 and 2," June 14, 1996. 3. Letter from D. R. Powell of Public Service Electric and Gas Company to NRC Document Control Desk "Response to Request for Additional Information," August 19, 1996. 4. Letter to D. H. Dorman of NRC from N. P. Smith of Seismic Qualification Utility Group "SQUG Generic Response to the Staff RAI," August 19, 1996. NRC RAI #1 Adequacy of Seismic Demand Determination (Ground Spectra and In-Structure/Floor Response Spectra).

The licensee's response to Question 5 of the staff's Request for Additional Information (RAI) dated May 30, 1996, concerning the use of ground response spectra for estimating seismic demand did not provide the requested information.

This issue was discussed in a meeting held between the Seismic Qualifications Utility Group ( SQUG) representatives and the staff on August 20, 1996. As a result of considerable discussions on the subject, the staff agreed to clarify the question.

The following is the revised (RAI) on this issue. Referring to the in-structure response spectra provided in your 120-day-response to the NRC's request in Supplement No. 1 to Generic Letter (GL) 87-02, dated May 22, 1992, the following information is requested:

NRC RAI #1a Identify structure(s) which have in-structure response spectra (5% critical damping) for elevations within 40-feet above the effective grade, which are higher in amplitude than 1.5 times the SQUG Bounding Spectrum.

1

• PSE&G Response to RAl#1 a PSE&G used the Seismic Qualification Utility Group (SQUG) Generic Implementation Procedure (GIP-2), Method A of Table 4-1 for comparing equipment seismic capacity to seismic demand for equipment mounted below about 40 feet above effective grade and where the equipment has a natural frequency greater than about 8 Hz. The PSE&G response to Question 1 a is based upon the Salem Site specific data required to demonstrate that Method A of Table 4-1 was appropriately applied for the Salem Site under certain limited conditions as specified in the GIP-2. The application of the GIP-2 Method A also includes the requirement that the SSE ground response spectrum (GRS) be identified at the free field ground surface. The Salem Site SSE ground response spectrum is defined at the free field ground surface. PSE&G has reviewed those applicable structures which have in-structure response spectra (ISRS) at 5% critical damping for elevations within 40 feet above the effective grade to determine if the ISRS are higher in amplitude than 1.5 times the SQUG Bounding Spectrum (BS). This review has determined that the applicable ISRS are lower in amplitude than 1.5 times the SQUG Bounding Spectrum in all cases except in the Auxiliary Building roof at elevation 140'. The ground elevation at Salem is 100'. The ISRS for this location is enveloped by 1.5 times the SQUG Bounding Spectrum except at the frequency of 10.5 Hz. The ISRS for this location and 1.5 times the SQUG Bounding Spectrum are shown on the attached Figure 1. This exceedance (less than 5%) does not affect the approach or results presented in the PSE&G submittal in response to Generic Letter 87-02 since the ISRS exceedance for this location was judged to be minimal. The attached Figure 2 compares GRS vs. Bounding Spectrum and was used for screening USI A-46 components at this location.

NRC RAl#1b With respect to the comparison of equipment seismic capacity and seismic demand, indicate which method in Table 4-1 of GIP-2 was used to evaluate the seismic adequacy for equipment installed on the corresponding floors in the structure(s) identified in Item (a) above. If you have elected to use Method A in Table 4-1 of the GIP-2, provide a technical justification for not using the in-structure response spectra provided in your 120-day-response.

It appears that some A-46 licensees are making an incorrect comparison between their plant's safe shutdown earthquake (SSE) ground motion response spectrum and the SQUG Bounding Spectrum.

The SSE ground motion response spectrum for most nuclear power plants is defined at the plant foundation level. The SQUG Bounding Spectrum is defined at the free field ground surface. For plants located at deep soil or rock sites, there may not be a significant difference between the ground motion amplitudes at the foundation level and those at 2

• the ground surface. However, for sites where a structure is founded on shallow soil, the' amplification of the ground motion from the foundation level to the ground surface may be significant.

PSE&G Response to RAl#1 b Method A of Table 4-1 of the GIP-2 (i.e., Figure 2, Comparison of BS vs. GRS) was used to compare the seismic capacity versus seismic demand for equipment located in the Auxiliary Building roof at elevation 140'. For Salem Units 1 and 2, the SSE Ground Response Spectrum is defined in the Salem UFSAR Section 2.5. Section 2.5.1 states that the plant is "designed to withstand free field ground earthquake acceleration levels of 20 percent of gravity horizontal, and 13.3 percent gravity vertical." Also please note that NUREG-5250 classifies Salem as a "deep soil" site. Therefore the application of GIP-2 Method A in Table 4-1 for the Salem Site has been appropriately used in accordance with the requirement that the SSE ground response spectrum is defined at the free field ground surface. NRC RAl#1c For the structure(s) identified in Item (a) above, provide the in-structure response spectra designated according to the height above the effective grade. If the structure response spectra identified in the 120-day-response to Supplement No. 1 to GL 87-02 was not used, provide the response spectra that were actually used to verify the seismic adequacy of equipment within the structures identified in Item (a) above. Also provide a comparison of these spectra to 1.5 times the Bounding Spectrum.

The licensees is requested to address this question on a plant-specific basis. PSE&G Response to RAl#1 c PSE&G previously transmitted the in-structure floor response spectra for Salem Units 1 and 2 to the NRC staff via letter NLR-N92134 dated September 21, 1992. PSE&G's responses to RAI numbers 1 a and 1 b provide the technical basis for the response to this question.

PSE&G has included as Figure 1 to this response the ISRS for elevation 140' of the Auxiliary Building compared to 1.5 times the SQUG Bounding Spectrum.

In addition, the SSE GRS at effective grade elevation 100' is included as Figure 2 and compared to ttie bounding spectrum.

NRC RAl#2 Soil Structure Interaction 3

• * ' . If the Soil Structure Interaction (SSI) analysis performed for the A-46 program and discussed in Reference 1 differs from the SSI analysis discussed in the Salem Final Safety Analysis Report, then provide the input data used to perform the SSI for the containment building in Reference 1 including name of the code used, results of the calculations performed such as maximum stresses at boundary elements of the foundation as well as the stresses at the containment building.

PSE&G Response to RAl#2 The Soil Structure Interactions (SSI) analysis discussed in PSE&G's submittal of the USI A-46 Walkdown Summary Report dated May 22, 1995 is the SSI analysis discussed in the Salem Updated Final Safety Analysis Report. The analysis is based on the approach and methodology given in the Salem UFSAR Sections 3.8.1.4.2 and 3. 7.2.1.1 which reference the Conrad Associates Report. NRC RAl#J Seismic Adequacy of Tanks and Heat Exchangers The licensee stated that the large flat bottom storage tanks on the Safe Shutdown Equipment List (SSEL) did not meet the screening guidelines of the Generic Implementation Procedure, Revision 2, as corrected on February 14, 1994 (GIP-2) and were identified as outliers.

The licensee further stated that detailed evaluations were performed in accordance with Appendix Hof the EPRI NP-6041. The EPRl.NP-6041 Appendix H methodology is known to yield less conservative results than those of GIP-2 Methodology.

Therefore, the staff does not accept the Appendix H methodology unless the licensee provides an adequate justification.

When a justification for use of Appendix H is not possible, the licensee should submit an alternate resolution for the outlier tanks or perform the necessary physical modifications to meet the acceptance criteria.

When an alternative analytical resolution is proposed, the licensee is requested to document a validation of the methodology and identify a way of predicting credible test data with sufficient margin. The licensee is also requested to identify the method chosen for evaluation of the tank, and provide a sample of the evaluation including tank anchorage evaluation.

PSE&G Response to RAl#J Attachment G of the initial submittal contains the Outlier Seismic Verification Sheets (OSVS) for the subject tanks. Section 2 of the OSVS contains the "proposed method of resolution".

The outlier evaluation for the tanks have not been performed as of this 4

• to the GIP-2 outliers.

The proposed method for resolution of the tanks is to perform a more refined analysis and evaluation.

The justification and validation for the proposed method that will be used to resolve these outliers will be included in the documentation.

The documentation will be available for NRG review upon completion of the proposed outlier evaluations and determination of the margin. As stated in the attached cover letter, PSE&G will disposition all outliers before the end of the second refueling outage following the receipt of the Salem specific Safety Evaluation Report (SER) that approves the use of the GIP-2 methodology for resolution of the USI A-46 Program. NRC RAl#4 Seismic Adequacy of Cable and Conduit Raceways In accordance with the GIP-2 guideline, the licensee performed a walkdown of the plant raceways and also performed a limited analytical review on 23 selected cable tray systems. However, during the recent review of another plant's implementation of the GIP-2 Guideline, the staff found that the procedure for ductile cable tray systems might not be sufficiently conservative.

The GIP-2 guideline stated that the ductile cable tray systems do not require an evaluation for lateral loads. The staff does not fully endorse this position and is currently pursuing a resolution of the cable tray system ductility issue with SQUG (Reference 4). A generic resolution, when established, should apply to the Salem plant cable trays as well, and the licensee should be expected to revise its evaluation of the Salem cable tray systems accordingly.

PSE&G Response to RAl#4 As stated in the question, the NRG Staff and representatives of the Seismic Qualification Utility Group (SQUG) are jointly seeking resolution of this issue. Accordingly, response to this RAI is being deferred pending resolution of the cable tray system ductility issue. NRC RAl#S Deviation from the GIP-2 Guidance In Reference 1 the licensee stated that it is committed to implement the GIP-2, including clarification, interpretation, and exceptions in SSER-2, and to communicate to the NRG staff any significant or programmatic deviations from the GIP-2 guidance.

The licensee further stated that the submittal confirms that no significant or programmatic deviations from the GIP-2 guidance were made. 5

• In response to the staff RAI (Reference 2), the licensee provided a typical list of the items that' deviated from the GIP-2 guideline (Reference 3). They are all minor in nature. However, they are characterized as representative.

The licensee should provide the worst case items (from a safety point of view) which deviate from the GIP-2 guideline but were categorized as not being significant.

In addition, the licensee is requested to clarify the definition of "safety significant" that the walkdown crew used to classify the deviation as significant or non-significant and provide a justification for why such a definition is adequate.

PSE&G Response to RAl#5 In response to the staff RAI (Reference 2), PSE&G provided a typical list of items that deviated from the GIP-2 guidelines (Reference 3). They are all minor in nature. Representative examples of the safety significance of these minor deviations are listed below: 1. PSE&G used the format contained in GIPPER (Stevenson

& Associates software package) for the Screening Evaluation Worksheets (SEWs) versus the forms contained in the GIP-2. The GIPPER forms include all caveats contained in the GIP-2. 2. Use of 1 3/8" diameter anchor bolt data for 1 1/2" diameter cast in place J-bolts for tanks since data for 1 1/2" diameter J-bolts is not available.

This results in a conservative estimation of anchorage capacity for these tanks. 3. Classified some l&C panels as class 18 rather than class 20 for conservatism.

This results in a conservative estimation for capacity.

4. Some expansion anchor bolts for wall mounted small electrical panels (Hoffman boxes) are less than 3/8" diameter (i.e., 1/4"). These are below GIP guidance of 3/8" diameter.

The Seismic Review Team (SRT) had a tug test performed to qualify equipment.

The tug test is a consistent method of verifying the adequacy of these components.

GIP-2 screening guidelines were used during the walkdown.

In all cases where judgments were exercised by the SRT, the affected documents associated with PSE&G USI A-46 implementation, such as walkdown data sheets, were appropriately annotated.

Determination of whether each deviation was "minor was made by qualified, experienced engineers who had completed the appropriate SQUG training course on the use and application of judgment for resolution of USI A-46. As 6

• demonstrated above, the minor deviations were either more conservative than or bounded by the GIP screening guidelines.

These deviations did not affect the seismic verification and seismic screening evaluation of a component performed in accordance with the GIP-2 requirements.

Based on the experiences, training and judgment of the SRT, all of these items are not considered safety significant.

7

'. 1.40 1.20 1.00 0.80 G 0.60 0.40 0.20 0.00 1.00 * --............

/ISRS I I I I

• 1.5 x Bounding Spectrum \ \ I \ -...._ A ......._ I.\ '\ I \ \ I \ v \ " I I I 10.00 LOG Hz Figure 1 \ \_ --" .---"-' -.. ___ -Comparison of In-Structure Resp*onse Spectrum (Aux. Bldg. El.140', Un-Broadened) vs. 1.5 Times SQUG Bounding Spectrum 100.00

..... ' 0.8 0.7 0.6 0.5 G 0.4 0.3 0.2 0.1 0 1 *

• Bounding Spectrum .********

/GRS . . . .........

' . *. . . . . *******************

10 LOG Hz Figure 2 Comparison of Ground Response Spectrum vs. SQUG Bounding Spectrum 100 I