ML110270187

Request for Additional Information, Emcb Non-Steam Dryer Review, Amendment Request for Extended Power Uprate to Increase the Maximum Reactor Core Power Operating Limit from 3898 to 4408 Mwt

ML110270187
Person / Time
Site:	Grand Gulf
Issue date:	01/27/2011
From:	Wang A Plant Licensing Branch IV
To:	Burford J, Millar D Entergy Operations
Wang, A B, NRR/DORL/LPLIV, 415-1445
References
TAC ME4679
Download: ML110270187 (3)

Text

From: Wang, Alan Sent: Thursday, January 27, 2011 2:16 PM To: 'Jerry Burford'; 'MILLAR, DANA' Cc: Burkhardt, Janet; Lent, Susan

Subject:

GNS EPU Request for Additional Information Related to Mechanical and Civil Engineering Branch Review Excluding the Steam dryer (ME4679)

Jerry and Dana, By letter dated September 8, 2010 (Agencywide Documents Access and Management System, Accession No. ML1002660403), Entergy Operations, Inc. (Entergy, the licensee), submitted a request to amend the Facility Operating License No. NPF-29 for Grand Gulf Nuclear Station, Unit 1 (GGNS). The licensee proposed a license amendment request (LAR) for an extended power uprate (EPU) to increase the maximum reactor core power operating limit from 3898 megawatts thermal (MWt) to 4408 MWt.

The U.S. Nuclear Regulatory Commission (NRC) staff has determined that the following additional information is needed for the NRC staff to complete our review of this amendment .

This request for additional information (RAI) was discussed with Mr. Jerry Burford of your staff on January 26, 2011, and it was agreed that a response would be provided within 30 days of receipt of this E-mail. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1445 or via e-mail at Alan.Wang@nrc.gov.

The following RAIs are related to the Mechanical and Civil Engineering Branch non-steam dryer portion of the LAR review. The steam dryer RAIs will be forwarded shortly.

(1) Section 2.2.2.2.1.2 of Attachment 5A to Reference 1, Structural Evaluation for Affected Safety-Related Piping, indicates that for the stress analyses of the main steam (MS) piping outside containment, the turbine stop valve closure (TSVC) loads used in these analyses were developed using a methodology which contrasts with the methodology found in the NRC-approved Constant Pressure Power Uprate Licensing Topical Report (CLTR or Reference 2), the latter of which utilizes scaling factors to develop these loads under EPU conditions. Please describe the development of the forcing functions applied in the stress analyses to model the TSVC loads and provide the bases for the regulatory acceptance of this methodology in place of the NRC-approved methodology.

Additionally, please indicate whether this forcing function was utilized in lieu of the NRC-approved methodology to evaluate the acceptability of other piping systems, including supports, for the proposed EPU implementation at GGNS.

(2) Section 2.2.2.2.1.2 of Attachment 5A to Reference 1 also indicates that the MS piping outside containment was evaluated for acceptability at EPU conditions by demonstrating compliance with the allowable limits of the code of record. The code of record, as indicated in this section, is provided as the:

[American Society of Mechanical Engineers] ASME [Boiler & Pressure Vessel]

B&PV Code,Section III, Subsection NB, 1974 Edition with Addenda through Summer 1975, with exceptions and use of some sub-sections from the 1977 Edition with Addenda through Summer 1979 and the 1980 Edition with Addenda through Summer 1981.

Please confirm that the exceptions noted above are consistent with the current licensing basis (CLB) requirements of the MS piping outside containment. If these exceptions are not part of the GGNS CLB for this system, please provide justification for evaluating these components against code requirements which are not part of the CLB for this system.

(3) Section 2.2.2.2.1.2 of Attachment 5A to Reference 1 also describes the structural evaluation of the feedwater (FW) piping system, which is affected by the proposed EPU implementation at GGNS. Please address the following items related to the evaluations performed for the FW piping system:

a) Please provide the Edition(s) and Addenda of the ASME B&PV Code utilized to demonstrate the acceptability of the FW piping inside containment. Additionally, please confirm that the Edition(s) and Addenda utilized to demonstrate the compliance of the FW system inside containment at EPU conditions is/are consistent with the GGNS CLB.

b) The description of the structural evaluation of the FW piping outside containment indicates that this portion of the FW piping system, including branch piping, was evaluated for acceptability at EPU conditions by demonstrating compliance with the allowable limits of the code of record. The code of record, as indicated in this section, is provided as the:

ASME B&PV Code,Section III, Subsection NB, 1974 Edition with Addenda through Summer 1975, with exceptions and use of some sub-sections from the 1977 Edition with Addenda through Summer 1979 and the 1980 Edition with Addenda through Summer 1981.

Please confirm that the exceptions noted above are consistent with the CLB requirements of the FW piping outside containment. If these exceptions are not part of the GGNS CLB for this system, please provide justification for evaluating these components against code requirements which are not part of the CLB for this system.

c) Table 2.2-3a of Attachment 5A to Reference 1 indicates that the FW piping experiences no percent-increase in stresses due to the implementation of an EPU at GGNS. Please provide additional details regarding these results, including a discussion of the impact that the EPU has on the individual loads which make up the ASME Code equations for which compliance must be demonstrated. Additionally, please discuss the assumptions which were made regarding the operating conditions of the FW system when the stress analyses for the system were performed for EPU conditions. The discussion of any assumptions should include, but not be limited to, the FW heaters out of service (FWHOOS) assumption included on page 1-13 and Note 9 to Table 2.2-7, which indicates that normal operations do not include the FWHOOS assumption. If the FWHOOS assumption has been included as part of the FW piping structural analyses, please provide justification that this assumption provides for a bounding FW piping structural analysis at EPU conditions.

(4) Section 2.2.2.2.2.2 of Attachment 5A to Reference 1 discusses the structural evaluations performed for balance-of-plant (BOP) piping affected by the proposed EPU implementation at GGNS. The affected BOP piping systems were evaluated for

acceptability at EPU conditions by demonstrating compliance with the allowable limits of the applicable codes of record. The code of record for the Class 2 and Class 3 piping, as indicated in this section, is provided as the, ASME B&PV Code,Section III, Division I, 1974 Edition with Addenda through Summer 1975, with some exceptions and use of the 1977 Edition with Addenda through Winter 1979 and the 1980 Edition with Addenda through Winter 1981. Please confirm that the exceptions noted above are consistent with the CLB requirements of the affected Class 2 and 3 BOP piping systems. If these exceptions are not part of the GGNS CLB for this system, please provide justification for evaluating these components against code requirements which are not part of the CLB for this system.

(5) The conclusions regarding the structural evaluations for all piping systems affected (safety-related and BOP) by the proposed EPU implementation at GGNS indicate that all pipe supports on the affected piping systems will maintain adequate design margin to accommodate the additional loads imposed by the EPU implementation. However, no information was provided to support this conclusion. Please provide the code(s) of record for the aforementioned piping supports and confirm that these supports were evaluated against the applicable provisions of their respective code(s) of record as part of the structural evaluation of the piping systems affected by the proposed EPU implementation at GGNS.

(6) As part of the piping structural evaluations performed in support of the proposed EPU implementation at GGNS, Tables 2.2-4a and 2.2-4c of Attachment 5A to Reference 1 appear to provide a quantitative summary of the most limiting nodes resulting from the stress analyses of the ASME Class 1 MS piping. In order to demonstrate compliance of these portions of the MS piping with the applicable code of record, the stresses and CUF values coupled with these limiting nodes were compared to the corresponding ASME Section III Subsection NB allowable values. Furthermore, Tables 2.2-4b and 2.2-4d evaluated each limiting node against the code allowable values from Equations 10, 12, 13, and 14 in an effort to demonstrate that the pipe stresses satisfied the criteria used at GGNS to postulate an intermediate pipe break. However, Table 2.2-4d (for MS lines B &

C) does not include information demonstrating that nodes 128 and 020 satisfy the GGNS pipe stress criteria for pipe break postulation though these nodes were denoted on Table 2.2-4c as limiting nodes with respect to Equations 10 and 14, respectively. Please provide the quantitative results for nodes 128 and 020 which supports the conclusion found in Section 2.2.1 of Attachment 5A to Reference 1, which states that no new break or crack locations are required to be postulated as a result of EPU implementation.

(7) In Section 2.2.2.3 of Attachment 5A to Reference 1, a number of components are determined to be consistent with the dispositions provided in a number of topical reports, including Reference 2. As such, it is concluded that these components are acceptable for operation at EPU conditions. While the NRC has approved the use of the methodologies within the three topical reports cited in Section 2.2.2.3 for dispositioning a number of reactor pressure vessel components with respect to EPU implementation evaluation, it is not clear which of these methodologies have been applied in dispositioning the components listed on pages 2-63 and 2-64 of Attachment 5A to Reference 1. For each component, please provide the specific provision(s) from the applicable topical report(s) cited which provides the basis for a components acceptability at EPU conditions.

(8) Table 2.2-7 of Attachment 5A to Reference 1 provides the stresses and CUFs for limiting components of the reactor pressure vessel. Specifically, this table illustrates the stresses and CUFs of these limiting components at the current power level, the EPU power level, and compares these values against the allowable stresses and CUF limit.

Regarding Table 2.2-7, please address the following:

a) For the first component, the FW Nozzle - Carbon Steel Replacement Safe End, the peak stress of this component decreases at EPU conditions when compared to the stress realized at current operating conditions. This appears discrepant based on the fact that the loading conditions at EPU conditions are more limiting than those at the current power level. Please provide a technical justification, including a description of any revised analyses performed for this component, which rectify this apparent discrepancy and justify its acceptability for operation at the proposed EPU power level.

b) For the second component, the FW Nozzle - Strainless Steel Clad Replacement Safe End, the stress at EPU conditions rises while the overall CUF at EPU decreases. However, Note 5 to Table 2.2-7 indicates that a reduced number of cycles and a finite element analysis (FEA) calculation of critical transients were considered in order to arrive at the EPU CUF for this component. Please provide justification, including the incorporation of operating experience, for reducing the number of cycles considered in evaluating the fatigue of this component at EPU conditions. Additionally, please provide additional information regarding the FEA (summary of analysis) performed on this component and how this was factored into the fatigue evaluation.

(9) Attachment 10 to Reference 1, Vibration Analysis and Testing Program, describes the procedures being implemented at GGNS to evaluate the effects of flow-induced vibration (FIV) on those piping systems which will be affected by flow increases as a result of the proposed EPU implementation at GGNS. With respect to the proposed EPU vibration monitoring program described in this attachment, please address the following:

a) Section 5.2 indicates that numerous modal analyses were performed on piping system models in an effort to determine additional locations susceptible to FIV following EPU implementation. Please discuss how the inertial and elastic properties of the piping systems were captured given that it is stated, Static loads, such as weight, were neglected.

b) Please indicate what computer program(s) and/or code(s) were utilized to perform the aforementioned modal analyses.

c) Reference 7.3 of Attachment 10 to Reference 1 indicates that the provisions of the ASME OM-S/G, Standards and Guides for Operation and Maintenance of Nuclear Power Plants, Part 3, 1987 Edition, were used in order to demonstrate the acceptability of the affected piping systems susceptible to FIV. Please confirm that the use of this version of the OM Code is in accordance with the CLB requirements at GGNS. If this is not the OM code of record for GGNS, please provide a technical justification for the use of a version which is not part of the GGNS CLB.

(10) From Section 2.3.4, Table 2.2-10 of Attachment 5A to Reference 1 presents the reactor internal pressure differences (RIPDs) for a number of reactor vessel internal

components under faulted conditions at the current power level and under the proposed EPU power level. Note 1 to Table 2.2-10 provides additional context on the results presented in this table, including information concerning the FWHOOS assumption which results in a reduced FW temperature (RFWT). Please indicate whether normal operating conditions or RFWT conditions result in bounding RIPD values and confirm that the bounding RIPDs were incorporated into the structural analyses of the reactor vessel internals in support of the proposed EPU implementation at GGNS.

References

1) Letter from M. A. Krupa, Entergy Operations, Inc., to NRC Document Control Desk, License Amendment Request - Extended Power Uprate - Grand Gulf Nuclear Station, Unit 1 - Docket No. 50-416 - License No. NPF-29, dated September 8, 2010. (ADAMS Accession No.: ML102660403)

2) GE Nuclear Energy, Constant Pressure Power Uprate, Licensing Topical Report NEDC-33004P-A, Revision 4, Class III (Proprietary), July 2003; and NEDO-33004, Class I (Non-proprietary), July 2003.

Alan Wang Project Manager (Grand Gulf Nuclear Station)

Nuclear Regulatory Commission Division of Operating Reactor Licensing