ML20210T214
| ML20210T214 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 09/08/1997 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9709150015 | |
| Download: ML20210T214 (5) | |
Text
-
e f
Dave M:vey Souther: Nuclear Vee Presdent Operstmg C:mpany f adey Project P0. 00: 1295 Birmirgham, Ataliama 35201 Tel205 992 5131 e,
SOUTHERN COMPANY Energy to Serve Your World" September 8, 1997 10CFR50.55a(g)(6)(ii)(A)
US Nuclear Regulatory Commission ATIM Document Control Desk Washington, DC 20555 Docket No.:
50 348 Joseph M. Farley - Unit 1 Request for Alternative to 10 CFR 50.55a(g)(6)(ii)(A)
Altamentedfnwioatig1L9fEcactor Pressutc3'cjiclEih Ladies and Gentlemen:
In acco; dance with the requirements of 10 CFR 50.55a(g)(6)(ii)(A), the reactor pressure vessel
'(RPV) shell welds on Plant Farley Unit I were examined during the Spring 1997 refueling outage.
For one of the RPV circumferential welds, physical limitations prevented Southern Nucles r Operating Company from meeting the requirement to examine more than 90% of the examination volume of that weld.
Ilased on the information and justification provided in the enclosure, Southern Nuclear Operating Company requests NRC authorization of an alternative examination per the provisions of 10 CFR 50.55a(g)(6)(ii)(A)(5) for this one weld.
If you have any questions, please advise.
Respectfully submitted, k
V Wf nO
/{ b Dave Morey SOM/maf: RPVLET. doc Enclosures ec:
Mr. L A. Reyes, Region 11 Administrator Mr. J. I. Zimmennan, NRR Project Manager Mr. T. M. Ross, Plant Sr. Resident inspector I
9709150015 970908 PDR ADOCK 05000348 P
PDR o
t Enclosure ErqunLfnditaatiysjo 10 CFR 50.55a @L6XiDIA)
Southern Nuclear Operating Company (SNC) has determined that the augmented examinations of the Plant Farley Unit I reactor pressure vessel (RPV) cannot be performed to the extent required by 10 CFR $0.53a(g)(6)(ii)(A) without undue hardship. In accordanec with 10 CFR 50.55a(g)(6)(ii)(A)(5),
SNC requests NRC authorization of an alternative examination based on other pertinent examinations performed to date which provide an acceptable level of quality and safety.
1.
Required Examinations 10 CFR 50.55a(g)(6)(ii)(A) requires all licensees to augment their RPV examinations by implementing once, as part of the inservice inspection interval in effect on September 8, 1992, the extent of examinations for reactor vessel shell welds speciDed in item 111.10 of Examination Category ll A, "Pressare Retaining Welds in Reactor Vessel,"in Table IWil-25001 of Subsection IWD of the 1989 Edition of ash 1E Section XI, Division I of the AShiE Iloiler and Pressure Vessel Code. To meet the requirements of 10 CFR 50.$f a(g)(6)(ii)(A), "more than 90% of the examination volume of each weld" shall be examined.
2.
Completed Examinations Southern Nuclear Operating Company contracted the NSSS vendor to perform these examinations. The ultrasonic examinations (UT) were performed utilizing a remote reactor vessel inspection tool to satisfy the requirements of the 1983 Edition of AShiE Section XI with Addenda through Summer 1983. Additionally, the requirements of Regulatory Guide 1.150 were followed.
On Unit 1, a total of seven RPV shell welds, three circumferential and four longitudinal, were examined to satisfy the requirements of both the augmented RPV shcIl weld rule and ash 1E Code Section XI. The examination results for these welds revealed no recordable indications that exceed the allowable standards of ash 1E Code Paragraph IWB 3500.
See Table I for actual coverage obtained on Unit 1.
3.
Alternative Examination The augmented examination of weld 1100 8 (the lower shell to bottom head circumferential weld) was limited based on physical con 0guration. Four core support lugs permanently attached to the inner surface of the vessel limit access to the weld, thereby, prohibiting greater than 90% examination. The weld received an 89.2% examination volume coverage. Enclosed Figure i shows the con 0guration of the weld.
Prior to the outage, SNC and the NSSS vendor personnel originally estimated the examination coverage of weld 1100-8 to be 83%. As a result, SNC investigated options that could potentially maximize the examination coverage of this weld.
4
- Oplion i Supskmentallhamination OfThe Weld From The OutcLDiameterEDL01 lhc_Ycust The evaluation for an OD examination showed that almost no increase in coverage would be obtained, Additionally, a significant burden would be involved with the radiation dose and the effort to correlate the inner and outer diameter coverage plots.
Therefore, a significant burden would be placed on SNC without a compensating increase in safety.
'Qption 2 Supp_kumataLIhammadon OfThe Weld From 1hc_ inner Diameter (lD) Using Multiple Stat 1L SNC estimated that coverage could be maximinxl to approximately 92%
through the use of transducer repositioning and by performing additional scans beyond those required by the ASME Code, it was decided that SNC would pursue Option 2; however, the fillet welds on the core support lugs were larger than expected, which resulted h the final coverage of 89.2%.
4.
Conclusion 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 perfonned to the maximum extent practical using state of the art equipment and techniques within the limitations of design and access of the RpV. All ucids, except weld i100 8, received 100% Code required examination coverage and SNC believes that if a pattern of degradation exists in this one weld, that the (Tr examination coverage of 89.2% would have detected it, Furthermore, the likelihood of a significant defect existing in the unexamined portion is extremely small.
Additionally, weld 1100 8 is not located in the beltline region and is therefore not as susceptible to irradiation embrittlement as are the beltline welds. As discussed above, the beltline welds were fully examined with no limitations.
The examination of the Farley Unit No. I RpV shell welds provides an acceptable level of quality and safety, and SNC concludes that the public health and safety will not be endangered by approval of this alternative.
=
=
TAllLE 1 AUGMENTED EXAMINATION OF REACTOR PRESSURE VESSEL, ULTRASONIC EXAMINATION COVERAGE i
CIRCUM FERENTI Al, WEl,DS Weld No.
Weld Description item No, Volumetric Coverage i
1100 2 Upper Shell To-Middle Shell 111.11 100 %
Circumferential Weld 4
i1005 Middle Shell To Lower Shell Bl.11
^
100 %
Circumferential Weld 1100-8 Lower Shell To-Bottom licad B 1.11 89.2 %
Circumferential Weld AVERAGE VOLUMETRIC COVERAGE - 96.4%
1,0NGITUDINAI, WEI.DS 4
Weld No.
Weld Description item No, Volumetric Coverage 1100-3 Middle Shell Course Bl 12 100 %
Longitudinal Weld 1100 4 Middle Shell Course Bl.12 100 %
Longitudinal Weld 1100-6 lower Shell Course Bl.12 100 %
Longitudinal Weld i100 7 Lower Shell Course Bl.12 100 %
longitudinal Weld AVERAGE VOLUMETRIC COVERAGE - 100%
,-.7-
l I
l i
,l1lll ll F
E L
RP E
O S 0T S 5
E
.OV 2T L
2 F
3 0
E S
SE EV V.
TA*
P 0
R S8 M G1O 1 1 U
,N L*
8ye 0'
er T 9 0 dt u O *,7 rg R
>/
l 2
eoi P
WFF 0
P t
U S
9'D 0 A
.L 9 C 7
O RT 6
5 i!
i J' 1
\\
\\s
- ,YM y
t 4
m5b 4
0
( h 5
V~
2 0
0 I5F
.E R
F 4
1 E
L RP E
O S 2T S
./
3 E
S
=
.OV 2T
, 5 p
3 F
3 0
1T.
\\
2
,g