ML23199A019
| ML23199A019 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/25/2023 |
| From: | Thomas Wengert Plant Licensing Branch IV |
| To: | Entergy Operations |
| Wengert T | |
| References | |
| EPID L-2022-LLR-0080 | |
| Download: ML23199A019 (1) | |
Text
September 25, 2023 ARKANSAS NUCLEAR ONE, UNITS 1 AND 2 - AUTHORIZATION AND SAFETY EVALUATION FOR ALTERNATIVE REQUEST ANO-CISI-002 (EPID L-2022-LLR-0080)
LICENSEE INFORMATION Recipients Name and Address: ANO Site Vice President Arkansas Nuclear One Entergy Operations, Inc.
N-TSB-58 1448 S.R. 333 Russellville, AR 72802 Licensee: Entergy Operations, Inc.
Plant Name and Units: Arkansas Nuclear One (ANO), Units 1 and 2.
Docket Nos.: 50-313 and 50-368 APPLICATION INFORMATION Submittal Date: November 10, 2022 Submittal: Agencywide Documents Access and Management System (ADAMS)
Accession No.: ML22316A001 Supplement Date: September 14, 2023 Supplement ADAMS Accession No.: ML23257A184 Applicable Containment Inservice Inspection (CISI) Interval and Interval Start/End Dates:
ANO, Unit 1, fifth 10-year CISI interval, current interval start date: May 31, 2017; current interval end date: May 30, 2027 ANO, Unit 2, fifth 10-year CISI interval, current interval start date: March 26, 2020; current interval end date: March 25, 2030 Alternative Provision: The licensee requested an alternative under Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1), Acceptable level of quality and safety.
Inservice Inspection (ISI) Requirement: American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, subsection IWL, table IWL-2500-1, Examination Category L-B, Unbonded Post-Tensioning System.
Applicable Code Edition and Addenda: ASME Code Section XI, 2007 Edition with the 2008 Addenda.
Brief Description of the Proposed Alternative: The licensees proposed alternatives, corresponding to the above code requirements, are requested for the current fifth 10-year CISI intervals through the end of the current renewed facility operating licenses for ANO, Units 1 and 2, as stated below:
- 1. For Item No. L2.10, the proposed alternative is to extend the interval of the examination from 10 to 15 years for ANO, Unit 1, such that the next tendon testing will be conducted in 2028, and from 10 to 18 years for ANO, Unit 2, such that the next tendon testing will be conducted in 2038. The proposed alternative also includes no additional tendon testing beyond year 2028 for ANO, Unit 1 for the remaining duration of the current renewed facility operating license, which expires on May 20, 2034.
- 2. For Item No. L2.20, the proposed alternative is that the removal and testing of selected tendon wires will only be performed when required by the Responsible Engineer. As noted in the supplemental letter dated September 14, 2023, the licensee has proposed to perform the L2.20 examinations in conjunction with the proposed L2.10 examinations described above.
- 3. For Item No. L2.30, the proposed alternative is to extend the interval of the examination from 5 to 10 years for ANO, Unit 1, to perform the next examination in 2028 and from 5 to 8 years for ANO, Unit 2, to perform the next examination in 2028. The proposed alternative also includes no additional examination beyond year 2028 for ANO, Unit 1, and one additional examination for ANO, Unit 2 in 2038 for the remaining durations of the current renewed facility operating licenses, which expire on May 20, 2034, and July 17, 2038, respectively.
- 4. For Item Nos. L2.40 and L2.50, the proposed alternatives are to extend the intervals of the examination from 5 to 10 years for ANO, Unit 1, to perform the next testing in 2028, and from 5 to 8 years for ANO, Unit 2, to perform the next testing in 2028, and to perform testing of Corrosion Protection Medium (CPM) material for corrosive ion and reserve alkalinity only when: (a) active corrosion is found on anchorage components and/or wires; (b) free water deemed significant by the Responsible Engineer is found at anchorages; (c) CPM absorbed water content exceeds the limits in ASME Code Section XI table IWL-2525-1, and (d) as otherwise specified by the Responsible Engineer. The proposed alternative also includes no additional testing beyond year 2028 for ANO, Unit 1, and one additional testing for ANO, Unit 2 in 2038 for the remaining durations of the current renewed facility operating licenses, which expire on May 20, 2034, and July 17, 2038, respectively.
STAFF EVALUATION The licensee proposed the request for alternative frequency to the containment unbonded post-tensioning system ISI (ANO-CISI-002) at ANO, Units 1 and 2. Specifically, the request concerns the following examination requirements in table IWL-2500-1 (L-B) of ASME Code,Section XI, subsection IWL.
Item No. L2.10 requires that selected tendon force and elongation be measured every 5 years (10 years for two units or more meeting subparagraph IWL-2421(b) alternative
scheduling requirements) in accordance with paragraph IWL-2522, Tendon Force and Elongation Measurements.
Item No. L2.20 requires that tendon single wire samples be removed and examined for corrosion examinations and mechanical damage as well as tested to obtain yield strength, ultimate tensile strength, and elongation on each removed wire. This inspection must be performed every 5 years (10 years for 2 units or more meeting subparagraph IWL-2421(b) alternative scheduling requirements) in accordance with paragraph IWL-2523, Tendon Wire and Strand Examination and Testing.
Item No. L2.30 requires that a detailed visual examination on selected tendon anchorage hardware and adjacent concrete extending 2 feet from the edge of the bearing plate be performed every 5 years (10 years for 2 units or more meeting subparagraph IWL-2421(b) alternative scheduling requirements) in accordance with paragraph IWL-2524, Examination of Tendon Anchorage Areas. In addition, the quantity of free water released from the anchorage end cap, as well as any free water that drains from the tendon during examination, must be documented.
Item No. L2.40 requires that samples of selected tendon CPM be obtained and analyzed every 5 years (10 years for 2 units or more meeting subparagraph IWL-2421(b) alternative scheduling requirements) in accordance with paragraph IWL-2525, Examination of Corrosion Protection Medium and Free Water.
Item No. L2.50 requires that samples of free water be obtained and analyzed every 5 years (10 years for 2 units or more meeting subparagraph IWL-2421(b) alternative scheduling requirements) in accordance with paragraph IWL-2525.
By letter dated September 25, 2008 (ML082490728), the NRC staff authorized Proposed Alternative ANO-CISI-001, which extended the 24-month requirement of subparagraph IWL-2421(a) to 37 months (the actual duration between the completion of post-tensioning operations for ANO, Units 1 and 2). Therefore, the licensee was authorized to use the modified inspection requirements for unbonded post-tensioning systems in IWL-2421, Sites with Multiple Plants, at ANO, Units 1 and 2.
The NRC staff reviewed the information provided in the alternative request and noted that the licensee will continue to conduct the general visual examinations and detailed visual examinations of suspect areas on a 5-year frequency as required by ASME Code Section XI table IWL-2500-1 (L-A) Examination Category L-A, Concrete. Any indications identified during these examinations may lead to additional examinations in accordance with table IWL-2500-1 (L-B), as determined by the Responsible Engineer. As required by ASME Code Section XI paragraph IWL-2511, Accessible Areas, this would include examination of the concrete surfaces and tendon end anchorage areas (end caps, bearing plates, concrete in the area) on a 5-year frequency to identify evidence of damage, deformation, water intrusion, corrosion, cracking or CPM leakage. Tendon end caps are required to be removed for this examination if there is evidence of tendon end cap deformation or damage.
The NRC staff also reviewed the plant-specific information and the summary results of examinations conducted for each of the requirements of ASME Code Section XI, subsection IWL, table IWL-2500-1 (L-B), Item Nos. L2.10, L2.20, L2.30, L2.40, and L2.50.
Item No. L2.10, Tendon Force Trends and Forecasts In its application dated November 10, 2022, the licensee stated in part, that the mean force in each of the Unit 1 and Unit 2 tendon groups is projected by log-linear regression, by 95%
[percent] lower confidence limit computations and, for the vertical and dome groups, by common tendon trends to remain above the specified minima until well beyond the current operating license end dates.
During a regulatory audit (ML23114A357), the NRC staff reviewed the lift-off force data presented in the Proposed Alternative ANO-CISI-002 calculations and tendon surveillance reports and verified that the projected forces remain above the minimum required value (MRV) through the next proposed inspection and through the end of the current operating license terms. Based on the statistical analyses of past surveillance results and the significant margin between the measured force trend (forecast) values and the MRV, the NRC staff finds it acceptable to extend the interval of the post-tensioning system examinations and tests (ASME Code,Section XI, table IWL 2500-1 (L-B), Item No. L2.10) for a one-time deferral for ANO, Unit 1, to perform the next tendon testing from 10 to 15 years in 2028, and from 10 to 18 years for ANO, Unit 2, to perform the next tendon testing in 2038.
The licensee also requested no additional tendon testing beyond year 2028 for ANO, Unit 1 for the remaining duration of the current renewed facility operating license. The NRC staff does not approve this portion of the request. The original scheduled tendon testing for ANO, Unit 1 shall be performed in 2033 if the second extended operating license is obtained. The NRC staff evaluation of the sixth CISI interval is discussed in the summary section of this SE.
Item No. L2.20, Wire Examination and Test Results In its application dated November 10, 2022, the licensee stated that: (1) the results of tests performed on ANO, Units 1 and 2, tendon wire specimens do not give any indication that tensile strength and ductility are decreasing over time, (2) the results show that strength and ductility meet the American Society of Testing and Materials (ASTM) A 421, Specification for Uncoated Stress Relieved Wire for Prestressed Concrete, acceptance criteria with exceptions, which were addressed in Nonconformance/Corrective Action Report (NCR) No. FN465-003 and Corrective Action Report (CR) #1-99-0352, and (3) visual examination results show that tendon wires are not corroding over time.
During a regulatory audit, the NRC staff reviewed NCR No. FN465-003, and determined that the samples from 3D120 showed no signs of corrosion degradation and the sampled tendon wires exceeded the minimum required yield strength of 192 thousand pounds per square inch (ksi) with margin. Therefore, tendon 3D120 is considered acceptable for service and still meets the design intent. The NRC staff also reviewed CR #1-99-0352 and determined that the loss of a single wire and the missing button head were accepted by the Responsible Engineer, and that the tendon remains code qualified in its current condition based on the licensees engineering assessment. The NRC staff further reviewed the test results of tendon wire specimens and determined that their ultimate strength and elongation meet the ASTM A421 acceptance criteria for ultimate strength (240 ksi minimum) and elongation (4 percent). In addition, visual examination demonstrated that the tendon wires are not corroding over time.
As noted in the supplemental letter dated September 14, 2023, the licensee has proposed to perform the L2.20 examinations in conjunction with the proposed L2.10 examinations.
Therefore, the NRC staff finds it acceptable to waive the requirement for sample wire removal and testing (ASME Code,Section XI, table IWL-2500-1 (L-B), Item No. L2.20) for a one-time deferral from 10 to 15 years to perform the next wire examination and testing for ANO, Unit 1 in
2028, and from 10 to 18 years to perform the next wire examination and testing for ANO, Unit 2 in 2038, and need only perform the removal and testing of selected tendon wires required by the Responsible Engineer if conditions indicative of wire degradation are found.
Similar to the NRC staff evaluation above for Item No. L2.10, the original scheduled wire examination and testing for ANO, Unit 1 shall be performed in 2033 if the second extended operating license is obtained. In addition, if conditions indicative of wire degradation are found, the removal and testing of selected tendon wires by the Responsible Engineer are required. The NRC staff evaluation of the sixth CISI interval is discussed in the summary section of this SE.
Item No. L2.30, Anchorage Hardware and Surrounding Concrete Inspection The licensee performed visual examinations of end anchorage areas for evidence of corrosion, presence of free water, broken wires or missing button heads, damage to/distortion of load bearing components and cracks in the concrete adjacent to bearing plates during each of the surveillances.
Based on the results of surveillances conducted to date, the licensee concluded, in part, that:
Corrosion of post-tensioning system hardware is minor in nature and will not impact the structural integrity of the Unit 1 or Unit 2 containment during the foreseeable future.
Accumulations of free water in post-tensioning system anchorage areas and ductwork are minor in nature and will not adversely affect system hardware during the foreseeable future.
The fraction of ineffective wires in the Unit 1 and Unit 2 containment tendons has, and will continue to have, no structural significance.
No damaged, cracked or distorted load bearing components (bearing plates, anchor heads, wedges, shims) have been found.
There is no structurally significant cracking in the concrete adjacent to the tendon end anchorage areas and no indication that this condition will change in the foreseeable future.
During a regulatory audit, the NRC staff reviewed the results of visual examinations of the tendon anchorage hardware and the surrounding concrete areas and determined that the tendon end anchorage hardware and adjacent concrete have performed well throughout the life of the plant (through the most recent surveillance) and show no trends of a deteriorating condition. Therefore, the NRC staff finds it acceptable to extend the interval of the examinations of the anchorage hardware and surrounding concrete (ASME Code Section XI, table IWL-2500-1 (L-B), Item No. L2.30) for a one-time deferral from 5 to 10 years to perform the next examination for ANO, Unit 1 in 2028, and from 5 to 8 years to perform the next examination for ANO, Unit 2 in 2028.
The proposed alternative also includes no additional examination beyond year 2028 for ANO, Unit 1 and one additional examination for ANO-2 in 2038 for the remaining durations of the current renewed facility operating licenses. The NRC staff does not approve this portion of the request. The original scheduled examination for ANO, Unit 1 shall be performed in 2033 if the second extended operating license is obtained, and the original scheduled examinations for ANO, Unit 2 shall be performed in 2030 and 2035. For ANO, Unit 2, the NRC staff authorizes
the licensee to perform examinations in 2033 and 2038 to align with other examinations. The NRC staff evaluation of the sixth CISI interval is discussed in the summary section of this SE.
Item Nos. L2.40 and L2.50, CPM and Free Water Testing In its application dated November 10, 2022, the licensee stated that the results of many of the earlier tendon CPM tests at ANO, Units 1 and 2, other than those that determine water content, are inconsistent and erratic due to sample preparation procedures that are unique to the Visconorust 2090P CPM product, and consequently, unfamiliar to laboratory testing personnel.
However, the licensee also stated that later tendon CPM tests are consistent, reflecting the increase in laboratory experience over time with these unique tests. The licensee further stated that testing of CPM for corrosive ion and reserve alkalinity will not be conducted on a 10-year frequency but will only be performed if corrosion or moisture conditions favoring corrosion are found.
During a regulatory audit, the NRC staff reviewed the results of tendon CPM tests at ANO, Units 1 and 2 for the surveillance year starting with surveillance year 30 and determined that concentrations of corrosive ions and absorbed water content have remained well below the specified acceptance (upper) limits, and all neutralization number test results were above the acceptance limit of zero. Therefore, the NRC staff finds it acceptable to extend the interval of the examination (ASME Section XI, table IWL-2500-1 (L-B), Items No. L2.40 and L2.50) for a one-time deferral from 5 to 10 years for ANO, Unit 1, to perform the next testing in 2028, and from 5 to 8 years for ANO, Unit 2, to perform the next testing in 2028, and to perform CPM tests for corrosive ion and reserve alkalinity when: (a) active corrosion is found on anchorage components and/or wires; (b) free water deemed significant by the Responsible Engineer is found at anchorages; (c) CPM absorbed water content exceeds the limits in ASME Code Section XI table IWL-2525-1, and (d) as otherwise specified by the Responsible Engineer.
The proposed alternative also includes no additional testing beyond year 2028 for ANO, Unit 1, and one additional testing for ANO, Unit 2 in 2038 for the remaining durations of the current renewed facility operating licenses. The NRC staff does not approve this portion of the request.
The original scheduled testing for ANO, Unit 1 shall be performed in 2033, and the original scheduled testing for ANO, Unit 2 shall be performed in 2030 and 2035. For ANO, Unit 2, the NRC staff authorizes the licensee to perform testing in 2033 and 2038 to align with other testing.
The NRC staff evaluation of the sixth CISI interval is discussed in the summary section of this SE.
Summary Based on the above evaluation, the NRC staff determines that the licensee has demonstrated adequate performance of the unbonded post-tensioning system by presenting plant-specific post-tensioning system inspection results and operating experience, and technical evaluations demonstrating that the applied tendon prestress will remain acceptable through the extended inspection intervals. Therefore, the NRC staff finds that the use of Proposed Alternative ANO-CISI-002 for the fifth 10-year IWL CISI interval for ANO, Units 1 and 2, provides an acceptable level of quality and safety.
The NRC staff authorizes the alternatives for the fifth 10-year IWL CISI interval for ANO, Units 1 and 2, as follows:
(1) Extend the interval of the post-tensioning system tendon lift-off force examinations (table IWL-2500-1 (L-B), Item No. L2.10) for a one-time deferral from 10 to 15 years for
ANO Unit 1, to perform the next tendon testing in 2028, and from 10 to 18 years for ANO, Unit 2, to perform the next tendon testing in 2038; (2) Waive the sample wire removal and testing (ASME Code Section XI table IWL-2500-1 (L-B), Item No. L2.20) for a one-time deferral from 10 to 15 years for ANO, Unit 1, to perform the next wire examination and testing in 2028, and from 10 to 18 years for ANO, Unit 2, to perform the next wire examination and testing in 2038, and only perform the removal and testing of selected tendon wires required by the Responsible Engineer if conditions indicative of wire degradation are found; (3) Extend the interval of the examinations for the anchorage hardware and surrounding concrete (ASME Section XI, table IWL-2500-1 (L-B), Item No. L2.30) for a one-time deferral from 5 to 10 years for ANO, Unit 1, to perform the next examination in 2028, and from 5 to 8 years for ANO, Unit 2, to perform the next examination in 2028; and (4) Extend the interval of the examinations (ASME Code Section XI table IWL-2500-1 (L-B),
Item Nos. L2.40 and L2.50) for a one-time deferral from 5 to 10 years for ANO, Unit 1, to perform the next testing in 2028, and from 5 to 8 years for ANO, Unit 2, to perform the next testing in 2028, and to perform testing of CPM material for corrosive ion and reserve alkalinity only when: (a) active corrosion is found on anchorage components and/or wires; (b) free water deemed significant by the Responsible Engineer is found at anchorages; (c) CPM absorbed water content exceeds the limits in ASME Code Section XI table IWL-2525-1, and (d) as otherwise specified by the Responsible Engineer.
The NRC staff also authorizes the alternatives for the sixth 10-year IWL CISI interval for ANO, Unit 2 to perform examination and testing (ASME Code Section XI table IWL 2500-1 (L-B),
Items No. L2.30, L2.40, and L2.50) in 2033 and 2038, instead of 2030 and 2035.
If deferred inspections from the fifth interval are conducted in the sixth CISI interval, the code edition used for the inspection shall be in accordance with 10 CFR 50.55a (g)(4)(ii), Applicable ISI Code: Successive 120-month intervals.
The NRC staff finds it reasonable to approve a one-time interval extension, based on its review of the plant-specific testing results and operating experience provided in the request. However, the NRC staff does not find it reasonable to extend the inspection intervals for the sixth ISI interval, without reviewing the results of the fifth IWL ISI inspection results and the results of the general visual examinations, and detailed visual examination of suspect areas, conducted prior to the initiation of the sixth ISI interval. Therefore, the NRC staff does not authorize the licensees request for the proposed alternatives to be applicable to the sixth ISI interval.
CONCLUSION As set forth above, the NRC staff determines that the proposed alternative, as described in the licensees letter dated November 10, 2022, as supplemented by letter dated September 14, 2023, and modified by the staff evaluation Summary section above, is acceptable as a one-time deferral on the basis that the proposed alternative provides an acceptable level of quality and safety.
The NRC staff concludes that the licensee has adequately addressed the regulatory requirements set forth in 10 CFR 50.55a(z)(1).
Accordingly, the NRC staff authorizes the use of proposed alternative ANO-CISI-002 at Arkansas Nuclear One, Units 1 and 2 for the fifth 10-year IWL CISI interval as a one-time deferral, as stipulated in the staff evaluation Summary section above.
All other requirements in ASME Code,Section XI for which relief or an alternative was not specifically requested and approved as part of this subject request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: G. Wang, NRR Date: September 25, 2023 Digitally signed by Jennifer L. Jennifer L. Dixon-Herrity Date: 2023.09.25 Dixon-Herrity 14:12:20 -04'00' Jennifer L. Dixon-Herrity, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation cc: Listserv
- by email OFFICE NRR/DORL/LPL4/PM* NRR/DORL/LPL4/LA* NRR/DEX/ESEB/BC* NRR/DORL/LPL4/BC*
NAME TWengert PBlechman ITseng JDixon-Herrity DATE 9/19/2023 7/19/2023 5/17/2023 9/25/2023