ML20196E484
| ML20196E484 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 11/30/1998 |
| From: | Beasley J SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LCV-1279, NUDOCS 9812040026 | |
| Download: ML20196E484 (6) | |
Text
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o J. Bernie Beasley.Jr P.E.
Southern Nuclear l
Vice President Operating Company, lac.
Vegtle Project
- 40 Ineemess Center Parkway R0. Box 1295 l
Birmingham. Alabama 35201 -
Tel 205.992.7110 fax 205 992.0403 SOUTHERN COMPANY Energy to Serve YourWorld" November 30,.1998 f
LCV-1279 Docket No.: 50-425 i
i U. S. Nuclear Regulatory Commission ATTN: Document Control Desk
. Washington,DC 20555 Ladies and Gentlemen:
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VOGTLE ELECTRIC GENERATING PLANT REQUEST FOR ALTERNATIVE TO 10 CFR 50.55a(g)(6)(ii)(A)
' AUGMENTED EXAMINATION OF REACTOR PRESSURE VESSEL l
In accordance with the requirements of 10 CFR 50.55a(g)(6)(ii)(A), the reactor pressure i
vessel (RPV) shell welds (ASME Section XI Category B-A, Item No. Bl.10) on Vogtle
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' Electric Generating Plant, Unit 2 (VEGP-2) were examined during the sixth maintenance / refueling outage (2R6) in Spring 1998. Physical limitations prevented completing the examination of more than ninety percent (90%) of the examination volume of one (1) RPV shell weld.
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- Based on the information and justification provided in the enclosure, NRC authorization of an alternative' examination per the provisions of 10 CFR 50.55a(g)(6)(ii)(A)(5) for one (1) RPV shell weld (21201-V6-001-WO6) is requested.
j Should there be any questions in this regard, please contact this ofrice.
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Sincerely,
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. B. Beasidy,'Jr l
JBB/JAE/jae
Enclosure:
Request for Alternative to 10 CFR 50.55a(g)(6)(ii)(A) 9812040026 981130 PDR ADOCK 05000425 P
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l U. S. Nuclear Regulatory Commission LCV-1279 l
Page Two '
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xc: Southern Nuclear Operating Company l
Mr. W. L. Burmeister (w/o enclosure)
Mr. J. T. Gasser (w/o enclosure)
.Mr. M. Sheibani (w/ enclosure)
SNC Document Management (w/ enclosure)
U. S. Nuclear Regulatory Commission l
Mr. D. H. JafTe, Senior Project Manager, NRR (w/cnclosure)
Mr. L. A. Reyes, Regional Administrator (w/ enclosure)'
Mr. J. Zeiler, Senior Resident Inspector, Vogtle (w/ enclosure) i i
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ENCLOSURE TO L
SOUTHERN NUCLEAR OPERATING COMPANY J
l LETTER LCV-1279 VOGTLE ELECTRIC GENERATING PLANT REQUEST FOR ALTERNATIVE TO 10 CFR 50.55a(g)(6)(ii)(A)
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1 Southern Nuclear Operating Company (SNC) has determined that the augmented j
examinations of the Vogtle Electric Generating Plant, Unit 2 (VEGP-2) reactor pressure vessel (RPV) cannot be performed to the extent required by 10 CFR 50.55a(g)(6)(ii)(A) without undue hardship. In accordance with the provisions of 10 CFR l
' 50.55a(g)(6)(ii)(A)(5), SNC requests NRC authorization of an alternative examination based on other pertinent examinations performed to date which provide an acceptable level of quality and safety.
REQUIRED EXAMINATIONS
-10 CFR 50.55a(g)(6)(ii)(A) requires that all licensees augment their RPV examinations l
by implementing once, as part of the inservice inspection interval in effect on September l
8,1992, the examination requirements for reactor pressure vessel shell welds specified in l
Item No. Bl.10 of Examination Category B-A, " Pressure Retaining Welds in Reactor l
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. Vessel", in Table IWB-2500-1 of Subsection IWB of the 1989 Edition of ASME Section XI, Division 1, of the ASME Boiler and Pressure Vessel Code. To meet the requirements of 10 CFR 50.55a(g)(6)(ii)(A),"more than 90% of the examination volume of each weld" l
shall be examined.
L COMPLETED EXAMINATIONS i-Southern Nuclear Operating Company contracted with the Nuclear Steam System Supply (NSSS) vendor to perform the examinations of the VEGP-2 RPV. The ultrasonic l'
- examinations (UT) were performed using a remote reactor vessel inspection tool to
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satisfy the requirements of the 1989 Edition of ASME Section XI and NRC Regulatory l
Guide 1.150. As a result of an early update of the inservice inspection program on VEGP-2 as authorized by the NRC, the 1989 Edition of ASME Section XI was used instead of the 1983 Edition with Addenda through Summer 1983. The following welds were examined in order to satisfy the requirements of both the augmented RPV shell weld rule and ASME Code Section XI:
Nine (9) longitudinal RPV shell welds (ASME Category B-A, Item No. Bl.12), and e
Two (2) nozzle dropout-to-RPV shell welds (considered ASME Category B-A, Item e
No. B l.10).
The examination results for these welds revealed no recordable indications that exceeded
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VOGTLE ELECTRIC GENERATING PLANT REQUEST FOR ALTERNATIVE TO 10 CFR 50.55a(g)(6)(ii)(A)
(continued)
COMPLETED EXAMINATIONS (continued) the allowable standards of ASME Code,Section XI, Paragraph IWB-3500. The coverage achieved for each weld is listed in Table 1.
ALTERNATIVE EXAMINATION Lower Shell-to-Bottom Head Weld (WO6)
Six (6) core support lugs are located on the lower shell of the RPV adjacent to lower shell-to-bottom head weld 21201-V6-001-WO6. These core support lugs obstruct movement of the mechanized examination equipment sled / transducer along the lower shell side (upper scan region) of circumferential weld WO6. As a result, examination coverage of this non-beltline weld from the inside diameter (ID) of the RPV was limited to approximately sixty-one percent (61%) of the weld length. This result is comparable to the sixty-six percent (66%) coverage reported during preservice examinations (PSI). A full-Code examination of this weld in service is not possible based on the following:
I General dose rates at the bottom of the vessel (as measured for VEGP-2 during its e
sixth maintenance / refueling outage (2R6)) are estimated to be approximately 200 i-millirem / hour (mr/hr) with contact dose rates at the insulation surface approximately 1 Rem / hour (R/hr).
i Nondestructive examination (NDE) personnel would need to perform thirteen UT e
scans for each area receiving the supplemental examinations. It is calculated that the dose to the NDE personnel in performing these examinations would be approximately l
3.25 R.
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Prior to performing examinations, personnel would need to erect any necessary scaffolding, remove insulation, and perform any required weld preparation in the high l
radiation field.
L This effort is further exacerbated by the fact that much of the RPV insulation used at e-VEGP was designed using rivets and screws and does not lend itself to easy removal and replacement. After examinations were completed, any scaffolding would need to be removed and insulation would need to be replaced. The actual number of person-hours spent in the vicinity of the RPV would not be known until such an effort was completed; however, the dose is estimated to be approximately 4.50 R.
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VOGTLE ELECTRIC GENERATING PLANT
,. REQUEST FOR ALTERNATIVE TO 10 CFR 50.55a(g)(6)(ii)(A)
(continued)
ALTERNATIVE EXAMINATION (continued)
NDE personnel would need to locate and mark the areas where the supplemental I
e examinations need to be performed. When perfonning ID examinations, limitations are located in respect to the core support lugs and the RPV flange, using indexing provided by the automated inspection tool. Translating these locations to the OD with a high degree of confidence would be an extremely difficult task while working i
in a high radiation field.
CONCLUSION The area not receiving ID examination is not located in the beltline region; therefore, concern with radiation embrittlement is not a factor. The lower shell-to-bc,ttom head weld had a complete ultrasonic examination performed from the OD in the fabrication shop, as a conservative measure, to ensure there were no unacceptable flaws that would need to be evaluated during preservice examinations. A review of fabrication shop ID and OD data indicates that no indications were observed in the areas not receiving ID inservice coverage; therefore, there is little likelihood of a crack propagating from a fabrication defect in the area.
The examination of RPV shell welds provides an acceptable level of quality and safety even though all could not be fully examined. The average examination coverage of all Category B-A, item No. Bl.10 welds was greater than ninety-five percent (95 %) and each weld (or portions of welds) located in the beltline region, i.e., welds WOS, W15, W16, and W17, received one-hundred percent (100%) coverage.
These completed examinations provide reasonable assurance that unacceptable service-induced flaws have not developed in these welds and that RPV shell weld integrity is maintained. The examinations were performed to the extent practical using state-of-the-art equipment and techniques available at the time of the examination in Spring 1998 within the limitations of design and access of the RPV. The evaluations and examinations performed meet the objectives of the augmented examinations defined in 10 CFR 50.55a(g)(6)(ii)(A); therefore, the NRC is requested to authorize the proposed altemative. Based on the results of the examinations discussed above, SNC concludes that the public health and safety will not be endangered.
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I VOGTLE ELECTRIC GENERATING PLANT REQUEST FOR ALTERNATIVE TO 10 CFR 50.55a(g)(6)(ii)(A) l (continued) i TABLE 1 j
VEGP-2 RPV WELDS EXAMINATION COVERGE
SUMMARY
(CATEGORY B-A / ITEM NO. Bl.10) l WELD ltem -
LIMITATION FAB OD
. PSI 2R6 WO4 B1.11 MAIN LOOP NOZZLES 100 %
100 %
>90%
l WO5 B1.11 N/A 100 %
100 %
100 %
j WO6 B l.11 CORE SUPPORT LUGS 100 %
66 %
61 %
W12 Bl.12 OUTLET NOZZLE 100 %
100 %
>90%
W13 Bl.12 OUTLET NOZZLE 100 %
100 %
>90%
W14 Bl.12 N/A 100 %
100 %
100 %
W15 Bl.12 N/A 100 %
100 %
100 %
W16 Bl.12 N/A 100 %
100 %
100 %
W17 Bl.12 N/A 100 %
100 %
100 %
W18 Bl.12 N/A 100 %
100 %
100 %
W19 Bl.12 N/A 100 %
100 %
100 %
W20 Bl.12 N/A 100 %
100 %
100 %
W207 Bl.10 N/A 100 %
100 %
100 %
W208 Bl.10 WO4 TRANSITION 100 %
100 %
>90%
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