ML20206F069
| ML20206F069 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 04/29/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20206F067 | List: |
| References | |
| NUDOCS 9905050325 | |
| Download: ML20206F069 (26) | |
Text
. . 9 %q n & UNITED STATES f 2 j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 3066H001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l QETHE THIRD 10-YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN MD ASSOCIATED REQUESTS FOR RELIEF EQB ARKANSAS NUCLEAR ONE. UNIT 1 ENTERGY OPERATIONS. INC.
DOCKET NUMBER: 50-313
1.0 INTRODUCTION
Inservice inspection (ISI) of the American Society of Mechanical Engineers (ASME) Code Class 1,2, and 3 components shall be performed in accordance with Section XI of the ASME Boller and Pressure Vessel Code (Code) and applicable addenda as required by Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(6)(g)(i). Section 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the Nuclear Regulatory Commission (NRC), if (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1,2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI, " Rules for Inservice inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests be conducted during the first 10-year interval and in subsequent intervals comply with the requirements in the latest edition and addenda of Sec. tion XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the lirnitations and modifications listed therein. The Code of record for Arkansas Nuclear One, Unit 1 (ANO-1), third 10-year ISI interval, is the 1992 Edition with a portion of the 1993 Addenda of Section XI of the ASME Boiler and Pressure Vessel Code. The licensee was authorized to use the 1992/1993 Addenda in an NRC safety evaluation dated December 12,1996.
Enclosure 9905050325 990429 3 DR ADOCK 0500 ,
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2.0 EVALUATION By letter dated June 25,1997, Entergy Operations, Inc., (EOl, the licensee) submitted its third 10-year interval ISI program plan and associated requests for relief for ANO-1. Additionally, in response to a request for additional information (RAI), a letter dated April 28,1998, documented that drawings were forwarded to the staff and the remaining portions of the RAI response were submitted by [[letter::1CAN129801, Forwards Response to NRC 971202 RAI Re ANO-1 Third 10-yr ISI Program.Rev 1 to Third 10-Yr Interval ISI Program for ANO-1, Encl|letter dated December 9,1998]]. The Idaho National Engineering and Environmental Laboratory (INEEL), has evaluated the information provided by the licensee in support of ANO-1's third 10-year interval ISI program plan and associated requests for relief.
Based on the results of the review, the staff adopts the contractor's conclusions and recommendations presented in the attached Technical Evaluation Report (TER).
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2.1 Program Review The staff determined that there were apparent discrepancies in the licensee's third 10-year ISI program plan. However, it should be noted that while these apparent discrepancies appear in l the program plan, the licensee may have additional information available to document the acceptability of each condition. if the licensee can adequately document the acceptability of each condition, no further information is required by the staff. The staff's review of the licensee's examination samples resulted in the following apparent discrepancies:
- 1. Item Numbers B3.130 and B3.140 require 100 percent volumetric examination coverage of all primary side steam generator (SG) nozzle-to-vessel welds and nozzle inside radius sections. Table 4.1 of the licensee's examination program shows a total of six primary side SG nozzle-to-vessel welds and six primary side SG inside radius sections. From the " Summary of all Third Interval inspections" tables it appears that only three primary side SG nozzle-to-vessel welds and three primary side SG inside radius sections have been selected for examination.
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! 2. Item Number B5.40 requires 100 percent volumetric and surface examination coverage of all pressurizer nozzle-to-safe end butt welds greater than nominal pipe size (NPS) 4.
Table 4.1 of the licensee's examination program shows a total of two pressurizer nozzle-to-safe end butt welds greater than NPS 4. From the " Summary of all Third Interval
- inspections" tables it appears that only one pressurizer nozzle-to-safe end butt weld greater than NPS 4 has been selected for examination.
- 3. Item Number B6.190 requires that visual examination, VT-1, be performed on pump flange surfaces when connections are disassemb6d. Table 4.1 of the licensee's examination program shows a total of four pump flange oudsces. From the " Summary of all Third Interval Inspections" tables it appears that no flange surfaces have been selected for examination.
- 4. Item Number B7.70 requires visual examination, VT-1, be performed on valve bolts, studs, and nuts. Bolts, studs, and nuts may be examined in place, under tension, when the connection is disassembled, or when the bolting is removed. Table 4.1 of the licensee's examination program shows a total of 23 components. From the " Summary of all Third Interval inspections" tables, it appears that no bolts, studs, or nuts have been scheduled for examination.
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- 5. Item Number B9.31 requires a surface and volumetric examination on branch pipe connection welds NPS 4 and larger. Item Number B9.32 requires a surface examination on branch pipe connection welds less than NPS 4. The total number of branch connection welds required for examination is 25 percent. Table 4.1 of the licensee's examinatien program shows a total of 2 B9.31 components and 14 B9.32 components.
From the " Summary of all Third Interval Inspections" tables, it appears that no branch connection have been selected for examination.
! 6. Item Numbers B10.10 and B10.20 in Code Case N-509 require a surface examination
! on pressure vessel integrally welded attachments and piping integrally welded l attachments. Table 4.1 of the licensee's examination program shows a total of 21 l B10.10 components and 1 B10.20 component. From the " Summary of all Third Interval l Inspections" tables, it appears that no B10.10 or B10.20 components have been selected for examination.
- 7. Item Number C5.51 requires a surface and volumetric examination on circumferential pipe welds of carbon or low alloy steel piping greater than or equal to 3/8-inch nominal wall thickness for piping greater than NPS 4. Item Number C5.81 requires a surface l examination on circumferential pipe welds of carbon or low alloy steel piping greater l than NPS 2. The welds selected for examination of C-F-2 welds shallinclude i
7.5 percent, but not less than 28 welds. It is unclear why the licensee has selected L
18 of 193 welds for item Number C5.51, and 1 of 18 welds for item Number C5.81.
- 8. Item Number F1.20 requires a visual examination, VT-3, on 15 percent of Class 2 piping supports. It is unclear why the licensee has selected 47 of 376 supports (12.5 percent) for examination.
l The licensee should reevaluate the discrepancies identified above and verify that all l examination categories are in compliance with Section XI Code requirements regarding l examination samples.
l 2.2 Relief Reauests The information provided by the licensee in support of the requests for relief from Code requirements has been evaluated and the basis for disposition is documented below.
Spauest for Relief No. 97-004: ASME Code,Section XI, Table IWB-2500-1, Examination Category B-D, items B3.90 and B3.100 require that, for reactor pressure vessel (RPV) nozzle welds and inner radius sections, at least 25 percent but not more than 50 percent (credited) of the nozzles shall be examined by the end of the first inspection period and the remainder by the end of the inspection interval. Exsmination Category B-F, item B5.10, Note (1) states that the reactor vessel nozzle-to-safe end weld examinations may be performed with the vessel nozzle examinations.
Pursuant to 10 CFR 50.55a(a)(3), the licensee has proposed to apply Code Case N-521,
" Alternative Rules for Deferral of Inspections of Nozzle-to-Vessel Welds, inside Radius Sections, and Nozzle-to-Safe End Welds of a Pressurized Water Reactor Vessel," on the following welds:
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B3.90 B3.100 B5.100 01-011 01-011R 01-025 l 01-012 01-012R 01-026 l 01-013 01-013R I
!'01-014 01-014R l 01-015 01-015R 01-016 01-016R
l Entergy Operations shall complete the required nozzle-to-vessel weld ;
examinations, the nozzle inside radius section examinations, and the nozzle-to-safe end weld examinations concurrent with the reactor vessel ten-year i examinations during the third period of the third ten-year inservice inspection interval, in accordance with Code Case N-521.
The Code requires the examination of at least 25 percent, but not more than 50 percent of RPV nozzles and associated inside radius (IR) sections and nozzle safe ends during the first inspection period. The licensee has requested to use Code Case N-521, which defers the examination of these areas until the end of the third 10-year intenfal.
Code Case N-521 states that the examination of RPV nozzles, IR sections, and nozzle-to-safe end welds may be deferred provided (a) no inservice repairs or replacements by welding have ever been performed on any of the subject areas, (b) none of the subject areas contains L identified flaws or relevant conditions that currently require successive inspections in accordance with IWB-2420(b), and (c) tha unit is not in the first interval. The licensee confirmed that these conditions have been met in the June 25,1997 letter. An additional requirement imposed by the NRC is that all subject areas are to be scheduled for examination such that the new sequence of examinations will not exceed 10 years between examinations.
The licensee examined all the subject areas during the third period of the second 10-year interval. By examining the nozzles, associated IR sections, and nozzle-to-safe end welds at the l end of the previous 10-year interval, the licensee has established a new sequence of l examinations and will not exceed 10 years between examinations. By meeting the conditions in the Code Case and by repeating the examinations at the end of the previous interval, the licensee's proposed alternative provides an acceptable level of quality and safety because the maximum time of 10 [ Code) years between inspections will not be exceeded.
The staff concludes that the licensee's proposed attemative would provide an acceptable level
' of quality and safety and therefore is authorized pursuant to 10 CFR 50.55a(a)(3)(i). The use of Code Case N-521 is authorized for the third 10-year interval at ANO-1, or until the Code Case
is approved for general use by reference in Regulatory Guide 1.147," Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1." After that time, the licensee may continue to use Code Case N 521 with the limitations, if any, listed in Regulatory Guide 1.147.
Reauest for Relief No. 97-005: ASME Code,Section XI, IWA-5242(a) requires that insulation be removed from pressure-retaining bolted connections for VT-2 visual examination in systems borated for the purpose of controlling reactivity.
Pursuant to 10 CFR 50.55a(a)(3), the licensee proposed to use Code Case N-533," Alternative Requirements for Vf-2 Visual Examination of Class 1 Insulated Pressure-Retaining Bolted Connections."
The Code requires the removal of allinsulation from pressure retaining bolted connections in systems borated for the purpose of controlling reactivity when performing VT-2 visual examinations during system pressure tests. As an alternative, the licensee has proposed to perform a system pressure test and associated VT-2 visual examination without removal of insulation from bolted connections on Class 1 and 2 systems. The system pressure tests will be augmented with a minimum 4-hour hold time prior to the VT-2 visual examination. The frequency of examinations will be in accordance with the requirements in Table IWB-2500-1 for Class 1 systems (each refueling outage) and Tables lWC-2500-1 for Class 2 systems (each period, not exceeding 40 months). In addition, with the systems depressurized, insulation will be removed from the bolted connections for direct visual examination each refueling outage for Class 1 systems, and each period (40 months) for Class 2 systems.
The licensee's proposed alternative is essentially equivalent to Code Case N-533 except the proposed alternative was extended to address Code Class 2 bolted connections. Code Case N-533 is currently under review by the NRC staff and has not yet been approved for use by incorporation into Regulatory Guide 1.147.
For Class 1 and 2 systems, the licensee's proposed alternative provides a thorough approach for ensuring the leak-tight integrity of systems borated for the purpose of controlling reactivity.
First, the 4-hour hold time should allow potential leakage to penetrate the insulation, thus providing a means of detecting significant leakage with the insulation in place. Further, by subsequently removing the insulation each refueling outage for Class 1 bolted connections, and each period (not exceeding 40 months) for Class 2 bolted connections, the licensee will be able to detect minor leakage indicated by the presence of boric acid residue. Therefore, the staff concluded that this two-phased approach provides an acceptable level of quality and safety for bolted connections in borated systems.
The staff concludes that the licensee's proposed alternative would provide an acceptable level of quality and safety and therefore is authorized pursuant to 10 CFR 50.55a(a)(3)(i). The use of Code Case N 533 is authorized for the third 10-year interval at ANO-1, or until the Code Case is approved for general use by reference in Regulatory Guide 1.147. After that time, the licensee may continue to use Code Case N-533 with the limitations, if any, listed in Regulatory Guide 1.147.
Reauest for Relief No. 97-003: ASME Code,Section XI, Examination Category C-F-1, items C5.11, C5.12, and C5.21, require that surface and/or volumetric examinations be performed on the welds selected. The welds selected for examination shall include 7.5 percent, but not less l
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than 28 welds, of all austenitic stainless steel or high alloy welds not exempted by IWC-1220.
(Some welds not exempted by IWC-1220 are not required to be nondestructively examined per Examination Category C-F-1. However, these welds shall be included in the total weld count to which the 7.5-percent sampling rate is applied.) The examinations shall be distributed as follows:
(a) the examinations shall be distributed among the Class 2 systems prorated, to the degree practicable, on the number of nonexempt austenitic stainless steel or high alloy welds in each system (i.e., if a system contains 30 percent of the nonexempt welds, then 30 percent of the nondestructive examinations required by Examination Category C-F-1 should be performed on that system);
(b) within a system, the examinations shall be distributed among terminal ends and structural discontinuities prorated, to the degree practicable, on the number of nonexempt terminal ends and structural discontinuities in that system; and (c) within each system, examinations shall be distributed between line sizes prorated to the degree practicable.
Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed to inspect a minimum of 7.5 percent of all non-exempt C-F-1 piping regardless of pipe wall thickness. The licensee stated:
A uniform 7.5% sampling rate will be applied to all Examination Category C-F-1 piping welds regardless of nominal wall thickness. The examination requirements shall be as follows:
- 1) Piping 23/8" thick will be subject to volumetric and surface examinations as stated in ASME Section XI.
- 2) Piping < 3/8" thick which is not subject to IE (Inspection and Enforcement)Bulletin 79-17 will be subject to a surface examination.
- 3) Piping < 3/8" thick which is subject to IE Bulletin 79-17 will be subject to a volumetric examination.
Systems considered subject to IE Bulletin 79-17 will be those that meet the definition of a ' stagnant, oxygenated, borated water system,' as stated in the bulletin.
The piping welds selected for examination will still be subject to the distribution requirements stated in ASME Section XI, Table IWC-2500-1, Examination Category C-F-1, Note (2).
The licensee has proposed to inspect a minimum of 7.5 percent of all non-exempt C-F-1 piping regardless of pipe wall thickness. The piping welds that comply with the C F-1 requirement (equal to or greater than 3/8-inch NWT [ nominal wall thickness]) will receive a full Code examination (volumetric and surface). The piping welds that are less than 3/8-inch NWT and
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are subject to IE Bulletin 79-17 will receive a volumetric examination. The piping welds that are less than 3/8-inch NWT and are not subject to IE Bulletin 79-17 will receive a surface examination. The proposed change reduces the number of examinations on piping welds greater than 3/8-inch [ wall thickness) but does not affect the overall examination sample size for J
' Class 2 piping welds since piping welds less than 3/8-inch will now be included in the
. examination san'.ple.
The staff determined that it is technically prudent to examine a representative sample of !
Class 2 thin-walled piping welds. This can be accomplished by either augmenting the examination sample or by substituting thin-walled welds for thick-walled welds. The licensee's proposed alternative will essentially substitute thin-walled piping for thick-walled piping. The licensee has proposed to perform volumetric examinations on piping less than 3/8-inch wall I thickness which is subject to IE Bulletin 79-17, and surface examinations on piping less than 3/8-inch wall thickness which is not subject to IE Bulletin 79-17.
While it is understood that volumetric examinations of large bore thin-walled Class 2 piping is ,
not required by the Code, the staff determined that portions of the large bore thin-walled )
Class 2 piping represent a significant group of welds with unique operational characteristics (i.e., lower pressures, lower flow rates, stagnant borated fluid) and should receive examinations commensurate to the heavy wall piping examinations. However, the licensee's proposed alternative to perform only volumetric examinations on piping with less than 3/8-inch wall thickness for piping which is subject to IE Bulletin 79-17 appears to be inconsistent with other thin-walled examination Code requirements of piping welds. While the volumetric examinations provide adequate assurance of detection of inside diameter (ID) initiated inservice flaws, the staff determined that adequate assurance of detection of outside diameter (OD) initiated flaws will not be provided. Additionally, it appears that the licensee has made commitments to IE Bulletin 79-17, and that the licensee's request is seeking, in part, relief from those commitments. The staff believes that relief from IE Bulletin 79-17 commitments does not fall within the scope of this evaluation.
In a telephone conference call on March 24,1999, regarding Relief Request 97-003, the licensee clarified that it was asking to eliminate the ultrasonic exam for piping with wall thickness less than 3/8-inch, which is not subject to IE Bulletin 79-17, and perform only a surface examination. In its relief request, the licensee did not provide technical justification as to why eliminating the volumetric exams for piping less than 3/8-inch NWT which is not subject to IE Bulletin 79-17, and its proposed attemative to perform a surface examination, provides equivalency or acceptable quality and safety. TNrefore, the licensee's proposed alternative is denied.
3.0 CONCLUSION
i Based on review of EOl's " Third Ten-Year Interval inservice inspection Plan For Arkansas Nuclear One, Unit 1," the response to NRC's request for additional information, and the recommendations for granting relief from the ISI examinations that cannot be performed to the extent required by Section XI of the ASME Code, the staff identified deviations from regulatory requirements or commitments in Relief Request 97-003. The licensee did not provide technical justification as to why eliminating the volumetric exams for piping less than 3/8-inch thick which
is not subject to IE Bulletin 79-17, and its proposed alternative to perform a surface examination provides equivalency or acceptable quality and safety. Therefore, the licensee's proposed alternative is denied.
Pursuant to 10 CFR 50.55a(a)(3)(l), the staff concludes that the alternatives contained in Requests for Relief Nos.97-004 and 97-005 provide an acceptable level of quality and safety.
Therefore, the licensee's proposed alternatives are authorized pursuant to 10 CFR 50.55a(a)(3)(i). In addition, the use of Code Cases N-521 and N-533, contained in Requests for Relief Nos.97-004, and 97-005, is authorized for the third 10-year interval at ANO-1, or until Code Cases N-521 and N-533 are approved for general use by reference in Regulatory Guide 1.147. After that time, the licensee may continue to use Code Cases N-521, and N-533 with the limitations, if any, listed in Regulatory Guide 1.147.
Attachment:
Technical Evaluation Report Principal contributor: Thomas McLellan Date: April 29, 1999
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