RS-14-328, Stations, Units 1 & 2 - Response to NRC Request for Additional Information, Set 44, Dated November 6, 2014, License Renewal Application

Stations, Units 1 & 2 - Response to NRC Request for Additional Information, Set 44, Dated November 6, 2014, License Renewal Application

ML14325A744
Person / Time
Site:	Byron, Braidwood
Issue date:	11/21/2014
From:	Gallagher M Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-14-328
Download: ML14325A744 (15)

Text

10 CFR 50 10 CFR 51 10 CFR 54 RS-14-328 November 21, 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:

Response to NRC Request for Additional Information, Set 44, dated November 6, 2014, related to the Byron Station, Units 1 and 2, and Braidwood 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 November 6, 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 44 (TAC NOS. MF1879, MF1880, MF1881, and MF1882)"

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.

Enclosure A contains the response to this request for additional information.

Enclosure B contains updates to sections of the LRA (except for the License Renewal Commitment List) affected by the responses.

November 21, 2014 U.S. Nuclear Regulatory Commission Page 2 Enclosure C provides an update to the License Renewal Commitment List (LRA Appendix A, Section A.5). There are no other 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 Respectfully,

Enclosures:

A. Response to Request for Additional Information B. Updates to affected LRA sections C. License Renewal Commitment List Change cc: Regional Administrator- NRC Region Ill 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-14-328 Enclosure A Page 1 of 5 Enclosure A Byron and Braidwood Stations (BBS), Units 1 and 2 License Renewal Application Response to Request for Additional Information RAI B.2.1.30-6

RS-14-328 Enclosure A Page 2 of 5 RAI B.2.1.30-6 Applicability:

Byron Station and Braidwood Station (BBS), all units

Background:

ASME Code Section XI, Subsection IWL, sub-article IWL-2310 requires that general visual examinations of concrete surfaces shall be performed, directly or remotely, in sufficient detail to identify areas of concrete deterioration and distress, such as described in ACI 201.1R and ACI 349.3R. GALL Report Aging Management Program (AMP) XI.S2, ASME Section XI, Subsection IWL, states that [q]uantitative acceptance criteria based on the Evaluation Criteria provided in Chapter 5 of ACI 349.3R also may be used to augment the qualitative assessment of the Responsible Engineer. To demonstrate consistency with the GALL Report, LRA Section B.2.1.30, ASME Section XI, Subsection IWL includes enhancements to the program (Commitment No. 30) to (1) explicitly require that areas of concrete deterioration and distress be recorded in accordance with the guidance provided in ACI 349.3R and (2) include the quantitative acceptance criteria in Chapter 5 of ACI 349.3R and use it to augment the qualitative assessment of the Responsible Engineer consistent with GALL Report AMP XI.S2.

However, during NRC Regional 71002 inspections in support of the review of the BBS LRA, the inspection team noted that visual inspections of areas of concrete deterioration are taken at a distance with the use of a telescope. The inspection team expressed concern regarding the applicants visual resolution capability to be used during the period of extended operation, to quantify degradation based on quantitative acceptance criteria described in Chapter 5 of ACI 349.3R.

Issue:

It is not clear what visual resolution capabilities will be used for concrete surface examination during the period of extended operation to ensure methods and equipment will provide sufficient quantitative measurements to evaluate against the quantitative criteria in ACI 349.3R.

Request:

Provide information to verify that sufficient visual resolution capability will be used during visual examinations of concrete surfaces of containment structures to detect and quantify forms of degradation for comparison against quantitative acceptance criteria based on Chapter 5 of ACI 349.3R.

RS-14-328 Enclosure A Page 3 of 5 Exelon Response:

The Byron and Braidwood (BBS) ASME Section XI, Subsection IWL (B.2.1.30) aging management (IWL) program is an existing program that includes the periodic visual examination of the concrete surfaces of concrete Containment Structures. A visual examination is performed on all accessible concrete surface areas, including coated areas, by the performance of direct and remote examinations. Existing Enhancements 4 and 5 of the IWL program will formalize the use of the ACI 349.3R guidance for the recording of concrete conditions and use of quantitative criteria in addition to qualitative criteria for evaluating the condition of the concrete as recommended in the GALL. However, Enhancement 4 and Enhancement 5 did not originally address visual resolution capability requirements. Enhancement 4 and Enhancement 5 are revised as a result of this RAI to address visual resolution capability requirements as described in the following sections. The following sections of this response provide information regarding the visual resolution capability used during direct and remote visual examinations of concrete surfaces, the evaluation of examination results, and a basis for a conclusion that sufficient visual resolution capability will be used during visual examinations of concrete surfaces.

1. Direct Examinations-The current examinations use personnel qualified for visual examinations in accordance with ASME Section XI, Subsection IWA-2200, Examination Methods, for general and detailed examinations of the concrete Containment Structures. The results of these examinations are used to quantify suspect areas and indications of degradation to compare against the quantitative acceptance criteria described in Chapter 5 of ACI 349.3R. The IWL program includes the use of appropriate tools such as flashlights or droplights, magnifying glasses, mirrors, depth gages, crack comparators, surface replication techniques and weld gages to supplement direct examination.

Personnel qualified for VT-3 examinations perform general visual examinations. A general visual examination is performed of all concrete surface areas, including coated areas, but not including inaccessible areas. The results of the general visual examinations are used to assess the general structural condition of the Containment Structures. The general visual examinations are performed in sufficient detail to identify areas of concrete deterioration and distress, such as described in ACI 201.1 R-68 and ACI 349.3 R-96 in accordance with IWL-2310(a). The general visual examinations have identified and documented cracks that are 0.040 wide.

Personnel qualified for VT-1 examinations perform detailed visual concrete examinations.

Selected areas, such as at tendon anchorages and those that indicate suspect areas, receive a detailed visual examination. The detailed visual examinations are used to determine the condition of tendon anchorages and the magnitude and extent of deterioration and distress in accordance with IWL-2524.1 and IWL-2310(b). The detailed examinations have identified and documented cracks that are 0.010 wide.

To ensure that sufficient visual resolution capability will be used during direct visual examination of concrete surfaces of Containment Structures, Enhancement 4, of the ASME Section XI, Subsection IWL (B.2.1.30) aging management program, is revised to formalize the current practice that the direct visual resolution capability be sufficient to detect concrete degradation at the levels described in Chapter 5 of ACI 349.3R.

RS-14-328 Enclosure A Page 4 of 5

2. Remote Examinations-Where access is sufficient, direct examinations are made of the concrete surfaces. Where access is insufficient, optical aids such as telescopes and binoculars are used to make remote examinations. Borescopes, mirrors, telescopes, closed circuit television, cameras or other devices may be used for remote examination, provided such devices or systems have a resolution capability equivalent to that attainable by direct visual examination. Mirrors may be used to improve the angle of vision and accessibility in constricted areas. Remote examinations can be either general or detailed examinations, the same as direct examinations.

For the Containment Structures at BBS, direct examinations can be made at the areas most likely to exhibit aging due to higher localized loads, exposure to higher temperatures, and higher amounts of water exposure. The areas subject to direct examination include all of the tendon anchorages, containment penetrations, the tendon tunnel, concrete at ground level, and the containment domes. The portions of the Containment Structures not normally accessible for direct examinations are elevated portions of the containment cylinders, not adjacent to other structures, so remote examinations are performed of these areas, which are bounded on all sides by areas subject to direct examination.

Remote examination methods and equipment are documented and demonstrated to ensure the required resolution is reliably obtained and repeatable, considering the distance and the viewing angle to the concrete surface. The resolution capability of the optical aids used for remote examinations at BBS has previously been demonstrated as equivalent to direct visual examination to the Responsible Engineer and to the Authorized Nuclear Inspector. Actual sizes of suspect areas and indications of degradation are estimated or bounded based on the established demonstrated resolution. The results of remote examination are evaluated as described below to determine if additional examinations or additional precision is required.

Remote examinations may be used for follow-up examinations to monitor suspect areas where direct examinations were previously performed.

To ensure that sufficient visual resolution capability will be used during remote visual examination of concrete surfaces of Containment Structures, Enhancement 4, of the ASME Section XI, Subsection IWL (B.2.1.30) aging management program, is revised to formalize the current practices that the remote visual resolution capability be sufficient to detect concrete degradation at the levels described in Chapter 5 of ACI 349.3R and that the resolution capability of the optical aids used for remote examinations be demonstrated as equivalent to direct visual examination.

3. Evaluation of Examination Results-In accordance with IWL and current procedures, the Responsible Engineer reviews and evaluates all of the examination results, no matter what the size of the suspect area or indication of degradation. As part of the evaluation of the results, the Responsible Engineer determines if additional examination or additional precision, such as by direct methods and direct measurement of the deterioration, or other testing, is required to evaluate the condition.

Precise measurements may not be necessary for all suspect areas or indications of degradation for a suspect area or indication of degradation to be evaluated against the quantitative acceptance criteria in Chapter 5 of ACI 349.3R.

ACI 349.3R is a generic document, meant to be used under a variety of programs. The quantitative acceptance criteria, based on Chapter 5 of ACI 349.3R, provides guidance on

RS-14-328 Enclosure A Page 5 of 5 whether a review or evaluation by the Responsible Engineer is required and if additional examination may be required to determine whether to repair or accept the observed degradation. The quantitative acceptance criteria consider the quantitative results of the concrete degradation recorded by the concrete examiners, with increasing levels of review and evaluation by the Responsible Engineer, corresponding to increasing levels of concrete degradation. An example of one of the elements of the quantitative acceptance criteria and guidance provided in ACI 349.3R is shown below.

A crack with a width less than 0.015 meets the tier 1 criterion for crack width, would be recorded by the concrete examiner, and could be accepted without a review or technical evaluation by the Responsible Engineer.

A crack with a width of 0.015 or greater and less than 0.04 meets the tier 2 criterion for crack width, would be recorded by the concrete examiner, and would require review by the Responsible Engineer and could be accepted without technical evaluation by the Responsible Engineer.

A crack with a width of greater than 0.04 exceeds the tier 2 criterion for crack width, would be recorded by the concrete examiner, and would require a technical evaluation by the Responsible Engineer.

The ACI 349.3R acceptance criteria are not specific limits to be generically used for immediate repair and accept-as-is decisions. The quantitative acceptance criteria in Chapter 5 of ACI 349.3R are used to provide guidance on the level and type of review or evaluation performed by the Responsible Engineer.

To ensure that sufficient visual resolution capability will be used during the visual examination of the concrete surfaces of Containment Structures, Enhancement 5, of the ASME Section XI, Subsection IWL (B.2.1.30) aging management program, is revised to formalize the current practice that the Responsible Engineer confirm that the visual resolution capability used for the concrete Containment Structure examinations was sufficient to evaluate the examination results against the quantitative criteria acceptance described in Chapter 5 of ACI 349.3R.

4. Conclusion-To ensure that sufficient visual resolution capability will be used during visual examination of concrete surfaces of Containment Structures, Enhancement 4, of the ASME Section XI, Subsection IWL (B.2.1.30) aging management program, is revised to add requirements that the visual resolution capability be sufficient to detect concrete degradation at the levels described in Chapter 5 of ACI 349.3R, and that the resolution capability of the optical aids used for remote examinations be demonstrated as equivalent to direct visual examination. In addition, Enhancement 5 is revised to require that the Responsible Engineer confirm that the visual resolution capability used for the concrete Containment Structure examinations was sufficient to evaluate the examination results against the quantitative criteria acceptance described in Chapter 5 of ACI 349.3R. LRA Appendix A, Section A.2.1.30, and LRA Appendix B, Section B.2.1.30, as well as LRA Appendix A, Table A.5, Item 30 are revised in Enclosure B and Enclosure C to reflect these changes. These changes ensure that sufficient visual resolution capability will be used, during visual examinations of concrete surfaces of containment structures, to detect and quantify forms of degradation, for comparison against quantitative acceptance criteria based on Chapter 5 of ACI 349.3R. As a result, the visual resolution capabilities of the methods and equipment, which will be used for concrete surface examinations during the period of extended operation, will provide sufficient quantitative measurements to evaluate against the quantitative criteria in ACI 349.3R.

RS-14-328 Enclosure B Page 1 of 3 Enclosure B Byron and Braidwood Stations, Units 1 and 2 License Renewal Application (LRA) updates resulting from the response to the following RAI:

RAI B.2.1.30-6 Note: To facilitate understanding, some LRA text is repeated in this Enclosure. Existing LRA text, as modified by subsequent submittals, is shown in normal font. Inserted text is highlighted with bolded italics.

RS-14-328 Enclosure B Page 2 of 3 As a result of the response to RAI B.2.1.30-6, described in Enclosure A of this letter, LRA Appendix A, Section A.2.1.30, page A-33, is revised as shown below to add detail to Enhancement 4 and Enhancement 5. Changes are highlighted with bolded italics for inserted text. Only Enhancement 4 and Enhancement 5 are shown. This RAI makes no other changes to this section.

A.2.1.30 ASME Section XI, Subsection IWL Enhancements

4. Explicitly require that areas of concrete deterioration and distress be recorded in accordance with the guidance provided in ACI 349.3R. The visual resolution capability of direct and remote examination techniques will be sufficient to detect concrete degradation at the levels described in Chapter 5 of ACI 349.3R. The resolution capability of the optical aids used for remote examinations will be demonstrated as equivalent to direct visual examination.

5. Include quantitative acceptance criteria, based on the "Evaluation Criteria" provided in Chapter 5 of ACI 349.3R, that will be used to augment the qualitative assessment of the Responsible Engineer. In addition, the Responsible Engineer will confirm that the visual resolution capability used for the concrete Containment Structure examinations was sufficient to evaluate the examination results against the quantitative criteria acceptance described in Chapter 5 of ACI 349.3R.

RS-14-328 Enclosure B Page 3 of 3 As a result of the response to RAI B.2.1.30-6, described in Enclosure A of this letter, LRA Appendix B, Section B.2.1.30, page B-196, is revised as shown below to add detail to Enhancement 4 and Enhancement 5. Changes are highlighted with bolded italics for inserted text. Only Enhancement 4 and Enhancement 5 are shown. This RAI makes no other changes to this section.

B.2.1.30 ASME Section XI, Subsection IWL Enhancements

4. Explicitly require that areas of concrete deterioration and distress be recorded in accordance with the guidance provided in ACI 349.3R. The visual resolution capability of direct and remote examination techniques will be sufficient to detect concrete degradation at the levels described in Chapter 5 of ACI 349.3R. The resolution capability of the optical aids used for remote examinations will be demonstrated as equivalent to direct visual examination.

Program Element Affected: Acceptance Criteria (Element 6)

5. Include quantitative acceptance criteria, based on the "Evaluation Criteria" provided in Chapter 5 of ACI 349.3R, that will be used to augment the qualitative assessment of the Responsible Engineer. In addition, the Responsible Engineer will confirm that the visual resolution capability used for the concrete Containment Structure examinations was sufficient to evaluate the examination results against the quantitative criteria acceptance described in Chapter 5 of ACI 349.3R.

Program Element Affected: Acceptance Criteria (Element 6)

RS-14-328 Enclosure C Page 1 of 5 Enclosure C Byron and Braidwood Stations (BBS) Units 1 and 2 License Renewal Commitment List Changes This Enclosure identifies commitments revised in this document and is an update to the Byron and Braidwood Station (BBS) LRA Appendix A, Table A.5 License Renewal Commitment List.

Any other actions discussed in the submittal represent intended or planned actions and are described to the NRC for the NRCs information and are not regulatory commitments. Changes are as a result of the Exelon response to the following RAI:

RAI B.2.1.30-6 Notes:

To facilitate understanding, portions of the original License Renewal Commitment List have been repeated in this Enclosure, with revisions indicated.

Existing LRA text, as modified by previous RAI responses, is shown in normal font.

Additions are highlighted with bolded italics.

RS-14-328 Enclosure C Page 2 of 5 As a result of the response to RAI B.2.1.30-6, described in Enclosure A of this letter, LRA Table A.5, Item 30, pages A-82 through A-84, is revised as shown below to add detail to Enhancement 4 and Enhancement 5. Additions are indicated with bolded italics for inserted text. This RAI makes no other changes to this section. Existing text from the LRA and text inserted as a result of the updated response to RAI B.2.1.30-3 (Exelon letter RS-14-183, dated 7/8/2014) is shown in normal font.

NO. PROGRAM OR IMPLEMENTATION COMMITMENT SOURCE TOPIC SCHEDULE 30 ASME Section XI, ASME Section XI, Subsection IWL is an existing program that will be Program to be enhanced prior to Section A.2.1.30 Subsection IWL enhanced to: the period of extended operation.

Exelon Letter

1. Include additional augmented examination requirements after RS-14-183 post-tensioning system repair/replacement activities in 7/8/2014 accordance with Table IWL-2521-2.

Updated response to

2. A one-time inspection of one (1) vertical and one (1) horizontal RAI B.2.1.30-3 tendon on each unit will be performed prior to the period of extended operation. The inspection will consist of visually examining one (1) wire from each of the two (2) types of tendons at a worst-case location based on evidence of free Exelon Letter water, grease discoloration, and grease chemistry results. This RS-14-328 location will serve as a leading indicator for potential 11/21/2014 degradation or tendon surface corrosion. The visual inspection of these wires will be performed in accordance with existing RAI B.2.1.30-6 station procedures used for inspections consistent with IWL-2523.2. The acceptance criteria will consist of each wire being free of any active corrosion, including general and pitting corrosion. In the event that the acceptance criteria are not met and corrosion is identified, the condition will be entered into the corrective action program. The condition will be evaluated to characterize the corrosion, determine the cause of the corrosion, the location, depth, extent of the condition, and applicability of the condition to other wires that comprise that tendon. Corrective actions may include activities such as

RS-14-328 Enclosure C Page 3 of 5 NO. PROGRAM OR IMPLEMENTATION COMMITMENT SOURCE TOPIC SCHEDULE grease analysis, replacement of grease within the tendon duct, additional wire inspections from the same tendon, evaluation of the tendon capacity, potential replacement of the tendon, and augmented inspections and grease sampling of other leading indicator tendons, based, in part, on previous evidence of free water, observed grease leakage, grease discoloration, and grease chemistry results. Specific corrective actions will depend upon the cause, extent of condition, and grease properties. These corrective actions will be consistent with those actions which would be evaluated during periodic Note 3 required IWL examinations (Braidwood only) .

3. In order to monitor for tendon exposure to free water and moisture and manage any potential adverse effects, a periodic tendon water monitoring and grease sampling program will be Note 3 implemented (Braidwood only) . The program will consist of:

a. A baseline inspection of tendon grease caps at the bottom of all vertical and dome tendons, as well as all below-grade horizontal tendons, prior to the period of extended operation. The baseline inspection will check for evidence of free water and grease discoloration, with further actions taken based on the condition of the grease.

b. A follow-up tendon grease cap inspection of all vertical and dome tendons, as well as all below-grade horizontal tendons, will be performed within 10 years of the initial inspection, using the same approach as the baseline inspection.

c. For those tendons where free water, moisture, and grease did not meet acceptance criteria during the two (2) previous inspections, periodic monitoring of grease chemistry and moisture, free water, and grease discoloration will be performed on a frequency not to exceed 10 years.

Tendons, which exhibit significant quantities of free water

RS-14-328 Enclosure C Page 4 of 5 NO. PROGRAM OR IMPLEMENTATION COMMITMENT SOURCE TOPIC SCHEDULE (e.g., more than eight ounces) during periodic monitoring, will be inspected more often, with the timing of follow-up inspections increased until a frequency is achieved that no longer results in significant amounts of free water observed during successive inspections. Tendon water inspection and draining frequencies may vary from annual to every ten (10) years, depending upon grease chemistry and moisture parameters meeting IWL acceptance criteria. The maximum ten (10) year periodic frequency is meant to address any tendons which exhibit evidence of free water but the quantity is observed to be insignificant, with no observable grease discoloration, and given that the tendon wasnt inspected for at least ten (10) years prior. More frequent follow-up inspections will be performed for tendons which exhibit insignificant quantities of free water, but were inspected within the ten (10) years prior. In all cases, the frequency of inspections for water in individual tendons will be adjusted to be commensurate with the severity of the conditions found during each examination.

d. Braidwood has performed augmented inspections on additional tendons beyond those selected for the ASME Section XI, Subsection IWL program. The Braidwood augmented inspections are performed on a 5 year frequency, in conjunction with the ASME Section XI, Subsection IWL aging management program. The current augmented examinations of additional tendons will continue until the periodic tendon water monitoring and grease sampling program described above is implemented.

Corrective actions will be taken as necessary to ensure that the tendon grease meets ASME Section XI, Subsection IWL requirements

4. Explicitly require that areas of concrete deterioration and distress be recorded in accordance with the guidance provided in ACI 349.3R. The visual resolution capability of direct and

RS-14-328 Enclosure C Page 5 of 5 NO. PROGRAM OR IMPLEMENTATION COMMITMENT SOURCE TOPIC SCHEDULE remote examination techniques will be sufficient to detect concrete degradation at the levels described in Chapter 5 of ACI 349.3R. The resolution capability of the optical aids used for remote examinations will be demonstrated as equivalent to direct visual examination.

5. Include quantitative acceptance criteria, based on the "Evaluation Criteria" provided in Chapter 5 of ACI 349.3R, that will be used to augment the qualitative assessment of the Responsible Engineer. In addition, the Responsible Engineer will confirm that the visual resolution capability used for the concrete Containment Structure examinations was sufficient to evaluate the examination results against the quantitative criteria acceptance described in Chapter 5 of ACI 349.3R.