ML14136A099

RAI Set 30

ML14136A099
Person / Time
Site:	Byron, Braidwood
Issue date:	05/22/2014
From:	Robinson L License Renewal Projects Branch 1
To:	Gallagher M Exelon Generation Co
Robinson L, 415-4115
References
TAC MF1879, TAC MF1880, TAC MF1881, TAC MF1882
Download: ML14136A099 (6)

Text

May 22, 2014 Mr. Michael P. Gallagher Vice President, License Renewal Projects Exelon Generation Company, LLC 200 Exelon Way Kennett Square, PA 19348

SUBJECT:

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 30 (TAC NOS. MF1879, MF1880, MF1881, AND MF1882)

Dear Mr. Gallagher:

By letter dated May 29, 2013, Exelon Generation Company, LLC, submitted an application pursuant to Title 10 of the Code of Federal Regulations Part 54, to renew the operating licenses NPF-37, NPF-66, NPF-72, and NPF-77 for Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2, respectively, for review by the U.S. Nuclear Regulatory Commission (NRC or the staff). The staff is reviewing the information contained in the license renewal application and has identified, in the enclosure, areas where additional information is needed to complete the review.

These requests for additional information were discussed with John Hufnagel, and a mutually agreeable date for the response is within 30 days from the date of this letter. If you have any questions, please contact me at 301-415-4115 or by e-mail at Lindsay.Robinson@nrc.gov.

Sincerely,

/RA/

Lindsay R. Robinson, Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-454, 50-455, 50-456, and 50-457

Enclosure:

Request for Additional Information cc w/encl: Listserv

ML14136A099 *concurred via email OFFICE LA:DLR* PM:RPB1:DLR BC:RPB1:DLR PM:RPB1:DLR NAME IKing LRobinson YDiazSanabria (JDaily for) LRobinson DATE 5/20/14 5/20/14 5/21/14 5/22/14 Letter to M.P. Gallagher from Lindsay R. Robinson dated May 22, 2014

SUBJECT:

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 30 (TAC NOS. MF1879, MF1880, MF1881, AND MF1882)

DISTRIBUTION EMAIL:

PUBLIC RidsNrrDlr Resource RidsNrrDlrRpb1 Resource RidsNrrDlrRarb Resource RidsNrrDlrRasb Resource RidsOgcMailCenter RidsNrrPMByron Resource RidsNrrPMBraidwood Resource LRobinson DMcIntyre, OPA JMcGhee, RIII EDuncan, RIII JBenjamin, RIII AGarmoe, RIII JRobbins, RIII VMitlyng, RIII PChandrathil, RIII

BYRON STATION, UNITS 1 AND 2 AND BRAIDWOOD STATION, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION REQUEST FOR ADDITIONAL INFORMATION, SET 30 (TAC NOS. MF1879, MF1880, MF1881, AND MF1882)

RAI B.2.1.31-1a Applicability:

Byron Station (Byron) and Braidwood Station (Braidwood), Units 1 and 2

Background:

The Generic Aging Lessons Learned (GALL) Report XI.S3 Program Description states that the requirements of American Society of Mechanical Engineers (ASME)Section XI, Subsection IWF, which is imposed by 10 CFR 50.55a, are augmented to include monitoring of high-strength structural bolting (actual measured yield strength greater than or equal to 150 ksi) for cracking.

The detection of aging effects program element states that volumetric examination may be waived with adequate plant-specific justification.

By letter dated March 4, 2014, the applicant responded to request for additional information (RAI) B.2.1.31-1, which indicated that the program will use plant-specific history on volumetric examinations of high-strength bolts greater than one-inch nominal diameter and periodic visual examinations to detect a corrosive environment with supplemental volumetric examinations (if needed) in order to justify taking an exception to the GALL Report recommendation that periodic volumetric examinations be performed.

The response to RAI B.2.1.31-1 states that the ASME Section XI, Subsection IWF Program will be enhanced (Enhancement #4) to perform one-time volumetric examinations of a sample of American Society for Testing and Materials (ASTM) A490 bolts greater than one-inch nominal diameter, for the detection of stress corrosion cracking (SCC) prior to the period of extended operation (PEO). The RAI response also states, [a]ny adverse results of the volumetric examinations will be entered into the corrective action program and will be evaluated by engineering to determine if additional actions are warranted such as expansion of sample size, scope, and frequency of any additional supplemental visual or volumetric examinations, as well as any code requirements specified by ASME Section XI, Subsection IWF.

Issue:

1. IWF-2430 contains requirements for the performance of additional examinations when VT-3 visual examinations, performed in accordance with Table IWF-2500-1, reveal flaws or relevant conditions that exceed the acceptance standards of IWF-3400. However, the staff notes that the volumetric examinations that will be performed on high-strength bolts to support a plant-specific exception to the GALL Report are not specifically called out in, nor specifically subject to, the requirements of IWF-2430 for additional examinations.

The ASME Section XI, Subsection IWF aging management program (AMP) has not established criteria for expansion in inspection scope for these components in the case of adverse results of volumetric examinations. The staff needs additional information regarding whether procedures for performing these examinations will include criteria for expansion in scope, consistent with the methodology of ASME Code Subsection IWF.

ENCLOSURE

2. If the one-time volumetric examinations show signs of cracking, it is not clear whether the ASME Section XI, Subsection IWF AMP would be revised to include periodic volumetric, instead of visual, examinations.

Request:

1. State whether the one-time volumetric examinations planned, on a sampling basis to support an exception to GALL Report recommendations, will be subject to criteria for expansion of inspection scope, similar to the methodology used by the ASME Code for IWF components.

2. If the one-time volumetric examinations show signs of cracking, state whether the program would be revised to include periodic volumetric examinations. If not, provide the supporting technical basis.

RAI B.2.1.31-1b Applicability:

Byron and Braidwood

Background:

GALL Report XI.S3 Program Description states that the requirements of ASME Section XI, Subsection IWF, which is imposed by 10 CFR 50.55a, are augmented to include monitoring of high-strength structural bolting (actual measured yield strength greater than or equal to 150 ksi) for cracking.

The detection of aging effects program element states that volumetric examination may be waived with adequate plant-specific justification. By letter dated March 4, 2014, the applicant responded to RAI B.2.31-1 and RAI B.2.31-3 regarding high strength ASTM A490 and high-strength A540 bolts, respectively, by stating that the program will justify an exception to the GALL Report recommendations using (1) plant-specific history of volumetric examinations for a representative sample of high-strength bolts and (2) periodic visual examinations of 100 percent of applicable bolting to detect a corrosive environment conducive to SCC potential prior to the PEO and at 10-year intervals thereafter. The RAI response states that conditions identified during the periodic visual examinations that identify a potential corrosive environment that supports SCC will be entered into the corrective action program.

The RAI response states that the periodic visual examinations will include parameters and criteria to identify if the bolting has been exposed to moisture or other contaminants by evidence of moisture, residue, foreign substance, or corrosion. The RAI response further states that adverse conditions identified during the periodic visual examination will be evaluated by engineering to determine if a bolt has been exposed to a corrosive environment with the potential to cause SCC. The conditions will be subjected to supplemental visual examination or analysis of residue for additional information to determine if there is a potential for SCC. The RAI response states that the bolts determined to have been exposed to an environment with the potential to cause SCC will be included in a sample population of bolts (20 percent of the entire population of bolts, with a maximum of 25 bolts) subject to supplemental volumetric examinations. The results of the volumetric examinations will be evaluated by engineering to determine if additional actions are warranted such as expanding the sample population, scope,

and frequency of any additional supplemental visual or volumetric examinations, as well as any code requirements specified by ASME Section XI, Subsection IWF.

Issue:

1. The RAI response states that the periodic visual examinations that will be performed will identify conditions that show evidence that a bolt has been exposed to a potentially corrosive environment and that an engineering evaluation will determine if the bolt has actually been exposed to a corrosive environment with the potential to cause SCC. The AMP does not address what factors engineering will consider in determining whether a potential corrosive environment is indeed a corrosive environment (and therefore the need to perform supplemental volumetric examinations), particularly when no moisture is present.

2. NUREG-1800, Standard Review Plan for Review of License Renewal Applications for Nuclear Power Plants (SRP-LR), states that the parameters monitored or inspected program element should identify the aging effects that the program manages and should provide a link between the parameters that will be monitored and how the monitoring of these parameters will ensure adequate aging management. The SRP-LR also states that the parameters monitored or inspected should be capable of detecting the presence and extent of aging effects. For the visual inspections proposed by the applicant to be conducted at a 10-year interval, the staff noted that the program relies on indications related to the current or former presence of moisture and does not directly detect the aging effect of cracking due to SCC. Given that these environmental impact indicators used to detect a corrosive environment could be removed over time (e.g., clean-up of water stains, painting of steel), the staff needs additional information to assess whether using visual inspections for the listed parameters at a 10-year interval will be able to ensure adequate aging management of high-strength (measured yield strength greater than 150 ksi) SA 540 bolts greater than 1 diameter.

Request:

For high-strength (measured yield strength greater than 150 ksi) SA 540 bolts greater than 1 diameter:

1. With regards to determining whether a potential corrosive environment identified during visual inspections is actually a corrosive environment which would lead to performing supplemental volumetric examinations, describe the qualitative or quantitative acceptance criteria that will be used to (a) determine whether a corrosive environment exists or existed and (b) conclude that supplemental volumetric examinations will be performed.

2. Clarify whether the acceptance criteria used for monitoring to detect this aging effect are the existence of environmental indicators that a corrosive environment exists or existed.

If not, state the acceptance criteria to be used for monitoring. If so, given that those environmental indicators of a corrosive environment could be removed prior to visual inspections being conducted, provide information to support a conclusion that monitoring these parameters using visual inspection over a 10-year interval will be effective in managing this aging effect even if the environmental indicators of a present or past corrosive environment are removed.