View source for RS-14-331, Update Associated with Earlier Responses to Set 29 RAI B.2.1.5-1a, Related to License Renewal Application

{{Adams
| number = ML14335A323
| issue date = 11/24/2014
| title = Update Associated with Earlier Responses to Set 29 RAI B.2.1.5-1a, Related to License Renewal Application
| author name = Gallagher M
| author affiliation = Exelon Generation Co, LLC
| addressee name = 
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000454, 05000455, 05000456, 05000457
| license number = NPF-037, NPF-066, NPF-072, NPF-077
| contact person = 
| case reference number = RS-14-331
| document type = Letter type:RS
| page count = 5
| project = 
| stage = Other
}}

=Text=
{{#Wiki_filter:dMichael                                                                             P. Gallagher Vice President, License Renewal A NOW                                                                         Exelon Nuclear ExeLon Generation@                                               200 Exelon Way Kennett Square, PA 19348 610 765 5958 Office 610 765 5956 Fax www.exeloncorp.conm michaelp.gallagher@exeloncorp.com 10 CFR 50 10 CFR 51 10 CFR 54 RS-1 4-331 November 24, 2014 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

==Subject:==
Update Associated with Earlier Responses to Set 29 RAI B.2.1.5-1a, related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, License Renewal Application

==References:==
: 1. Letter from Michael P. Gallagher, Exelon Generation Company LLC (Exelon) to NRC Document Control Desk, dated May 29, 2013, "Application for Renewed Operating Licenses"
: 2. Letter from Lindsay R. Robinson, US NRC to Michael P. Gallagher, Exelon, dated June 4, 2014, "Request for Additional Information for the Review of the Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2, License Renewal Application, Set 29 (TAC NOS. MF1879, MF1880, MF1881, and MF1882)"
: 3. Letter from Michael P. Gallagher, Exelon, to NRC Document Control Desk, dated June 18, 2014, "Responses to NRC Requests for Additional Information, Set 29, dated June 4, 2014, related to the Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2, License Renewal Application"
: 4. Letter from Michael P. Gallagher, Exelon, to NRC Document Control Desk, dated September 4, 2014, "Interim Update Related to Earlier Response to Set 29 RAI B.2.1.5-1a, related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, License Renewal Application" 15t

November 24, 2014 U.S. Nuclear Regulatory Commission Page 2 In Reference 1, Exelon Generation Company, LLC (Exelon) submitted the License Renewal Application (LRA) for the Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 (BBS). In Reference 2, the NRC requested additional information to support staff review of the LRA. In Reference 3, Exelon responded to these RAIs, including providing information on an analysis being performed related to control rod drive mechanism (CRDM) housing wear under request for additional information (RAI) B.2.1.5-1a.
Reference 4 provided the NRC staff with an interim update associated with the CRDM housing wear analysis, including notification that Exelon would provide the final analysis results in November, 2014. This letter provides these final results.
In summary, the final analysis demonstrates ASME Code qualification for the CRDM housing with the maximum possible wear depth of 0.1075 inches, thus ensuring that this wear will not impact CRDM housing integrity at BBS.
The Enclosure describes the technical basis of the analysis and specific references for the acceptance criteria of the analysis (e.g., ASME Code Section III Edition and paragraphs and current license basis document sections). It also confirms that the acceptance criteria adequately address the design, normal, upset, emergency, fault, testing, and cyclic (i.e., fatigue analysis) conditions in the Updated Final Safety Analysis Report (UFSAR)
Section 3.9 and its subsections.
This analysis has just been completed, and additional evaluation is required to determine if any changes are required to the LRA. Exelon will provide the NRC Staff with an update, when the evaluation is completed.
There are no new or revised regulatory commitments contained in this letter.
If you have any questions, please contact Mr. Al Fulvio, Manager, Exelon License Renewal, at 610-765-5936.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on       i11-2,4"244 Respectfully, Michael P. Gallagher Vice President - License Renewal Projects Exelon Generation Company, LLC

==Enclosure:==
Summary of Control Rod Drive Mechanism Housing Wear Analysis

November 24, 2014 U.S. Nuclear Regulatory Commission Page 3 cc:    Regional Administrator - NRC Region III NRC Project Manager (Safety Review), NRR-DLR NRC Project Manager (Environmental Review), NRR-DLR NRC Senior Resident Inspector, Braidwood Station NRC Senior Resident Inspector, Byron Station NRC Project Manager, NRR-DORL-Braidwood and Byron Stations Illinois Emergency Management Agency - Division of Nuclear Safety

RS-14-331 Enclosure A Page 1 of 2 Enclosure Summary of Control Rod Drive Mechanism Housing Wear Analysis Exelon participated in the Pressurized Water Reactor Owners Group project, which generically qualified the control rod drive mechanism (CRDM) nozzle (housing) with a conservative depth of inside surface wear. This project completed a detailed analysis1 demonstrating the ASME Code acceptance criteria was met for the hypothetical maximum possible housing wear depth of 0.1075 inches. The final analysis has confirmed that the maximum possible housing wear depth of 0.1075 inches will not impact CRDM housing integrity at Byron and Braidwood Stations, Units 1 and 2. The results of the detailed analysis are being communicated to the Staff in this response.
Since the analysis evaluated the loads and transients for several industry plants, the most limiting loads were selected and provided a bounding analysis for all the units. Primary stress evaluations were performed using classical stress equations. Primary plus secondary stress intensity ranges and fatigue usage factors were determined by finite element analysis. Based on the completed analysis for this project, evaluations of the stresses and fatigue usage factors determined that the maximum wear depth could be qualified according to ASME Code, Section Il, Subarticle NB-3200. The applicable ASME Code is the 1971 Edition through Summer 1973 Addenda, which was the original code of construction. The detailed analysis addressed the design, normal, upset, emergency, fault, testing, and cyclic (i.e., fatigue analysis) conditions consistent with the requirements of the updated final safety analysis report (UFSAR) Section 3.9 and its subsections. The acceptance criteria that were used in accordance with the ASME Code, Section III, are listed by section in Table 1 (below) for the various code conditions. The acceptance criteria in ASME Code, Section III, Subarticle NB-3225 are explained further in the ASME Code, Section III, Appendix F sections as listed in the table. The current licensing basis requirements are listed in the UFSAR Table 3.9-3.
The transient data set used in the fatigue analysis bounds the number of transient occurrences, and transient severity of the design transients applicable to Byron and Braidwood Stations, Units 1 and 2. The design transients are listed in UFSAR Table 3.9-1.
The License Renewal Application (Tables 4.3.1-1 and 4.3.1-4) presented each of the design transients and their projected cycles (occurrences) for 60 years of operation and concluded the design transient occurrences were acceptable for the period of extended operation.
Therefore, since the fatigue analysis uses transient occurrences and transient severities which bound the Byron and Braidwood Stations, Units 1 and 2 design transient occurrences and transient severity, the fatigue analysis is valid for the period of extended operation.
With the maximum possible CRDM housing wear of 0.1075 inches, the analysis has confirmed the ASME Code requirements are met for the period of extended operation.
Therefore, no further examinations are required to monitor for wear on the CRDM housings.
This generic analysis has just been completed, and additional evaluation is required to determine if any changes are required to the LRA. Exelon will provide the NRC Staff with an update, when the evaluation is completed.
1 PWROG-14067-P, Revision 0, "Generic ASME Code Evaluation of a CRDM Housing with Inside Surface Wear, "dated November 2014

RS-14-331 Enclosure A Page 2 of 2 Table 1 ode Code                    Section              Stress        Applicable Code Condition                                        Category       Acceptance Criteria NB-3221.1                    Pm                < Sm Design                  NB-3221.3                 PL + Pb            < 1.5 Sm NB-3222.2                  P +Q              < 3.0 Sm NB-3222.4             Fatigue (Cyclic)          -<1.0 NB-3223(a)                   Pm                < Sm Upset                  NB-3223(a)                PL + Pb            < 1.5 Sm NB-3223(a)                 P +Q              < 3.0 Sm NB-3224.1                    Pm              < 1.2 Sm Emergency                NB-3224.1                 PL + Pb         5 1.5 (1.2 Sm)
NB-3225/F- 1323.1(b)
NB-3225/F-1331.1(a)               Pm              <2.4 Sm Faulted            NB-3225/F-1323.1(b)
NB-3225/F-1331.1(c)(1)           PL + Pb         < 1.5 (2.4 Sm)
NB-3225/F-1323.1(b)
NB-3225/F-1331.1(d)              Tavg             - 0.42 Su Test                  NB-3226(a)                   Pm              < 0.90 Sy NB-3226(b)                Pm + Pb           < 1.35 Sy Pm - general primary membrane stress intensity PL - local primary membrane stress intensity Pb - primary bending stress intensity P + Q - primary + secondary stress intensity range Sm - design stress intensity Su - ultimate tensile stress Sy - yield strength Tavg - shear stress}}