ML16245A571
| ML16245A571 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/26/1981 |
| From: | Wagner P Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8104030814 | |
| Download: ML16245A571 (6) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, 0D. C. 20555 March 26, 1981 Dockets Nos.
50-269, 50-270 and 50-287 LICENSEE:
DUKE POWER COMPANY (DPC) c' FACILITY:
OCONEE NUCLEAR STATION, UNITS NOS. 1, 2 AND 1
SUBJECT:
SUMMARY
OF MEETING HELD ON MARCH 24, 1981 WITH REPR ITATIVES OF DPC A meeting was held on March 24, 1981 with representatives of DPC to discuss the inservice inspection program to be completed during the Oconee Unit 1 refueling outage scheduled to commence in mid-June 1981. A list of attendees is attached as Enclosure 1.
The meeting was scheduled at the request of DPC to obtain NRC comments on the planned inservice inspections (ISI) of the Oconee 1 reactor pressure vessel.
It is DPC's intention to complete all needed ISI on the reactor vessel during the forthcoming refueling outage to preclude the necessity of defueling again in subsequent reloads within the next 10 year examination period. The DPC presentation is included as Enclosure 2.
The.only areas of continued disagreement between the staff and DPC relate to the sizing and reporting of flaws down.to the 20% range and th e estimation of error bands for all reportable flaws.
The staff stated that such require ments were necessary to ensure that detected flaws were adequately investi gated to provide reasonable assurance of their actual size and for comparison data during subsequent inspections..
DPC representatives agreed to evaluate the impact, in both time and costs, of fulfilling these requirements (which are contained in the staff's draft Regulatory.Guide on this subject) and contact us for further discussions if alternatives are considered necessary.
Philip C. Wagner, Project Manager Operating Reactors Branch #4 Division of Licensing
Enclosures:
- 1. List of Attendees
- 2.
DPC Mtg. Agenda, cc w/enclosures:
See last page o
8 1 0 4 0 3oo/q
Encl osure 1 LIST OF ATTENDEES 3/24/81 DPC/NRC MEETING ON 3/24/81 DPC/NRC MEETING ON ISI NRC DPC P. C. Wagner David E. Whitaker W. S. Hazelton C. B. Cheezem J. R. Glerm R. L. Gill M. R. Hum*
C. W. Hendrit, Jr.
Jim Kennedy Earl J. Brown F. B. Fillen W. J. Collins B&W ORNL B. J. Short J. H. Smith Sanford Hellman Thomas Smith SANDIA NAT'L LABS C. J. Hudson John H. Gieske M. G. Hacker K. E. Moore Consul tant F. J. Sattler DUKE POWER COMPANY OCONEE NUCLEAR STATION UNIT 1 10-Year SI, In-Vessel Examination Meeting With NRC AGENDA I.
INTRODUCTION II.
PURPOSE To seek NRC concurrence of the Duke Plan for examination of the beltline region welds of Oconee 1 during the forthcoming 10-year ISI.
III.
BACKGROUND IV.
THE OCONEE 1 IN-VESSEL WELD ELAMINATION PLAN (Presentation by Duke Power Company and Babcock &Wilcox)
V.
DISCUSSoN/ IDENTIFI CATION OF ACTICN sTEVS VI.
ADJOURN
SUMMARY
DUKE/B&W/NRC MEETING 3-24-81 The Oconee 10-year reactor vessel ISI wil1 be conducted in accordance with ASME Section V, Article 4, and as supplemented by the recommendations of the NRC draft regulatory guide, "Ultrasonic Testing of Reactor Vessel Welds During Preservice and Inservice Inspection", to the extent proposed herein.
ISI Plan A. ASME Section V, Article 4 B.
NRC Draft Regulatory Guide, Task No. SC-705-4 Regulatory Position B&W Position
- 1. Instrument Performance Checks Compliance
- 2.
Calibration Compliance/
Clarification
- 3. Near Surface Examination & Resolution Compliance
- 4.
Beam Profile Compliance
- 5.
Scanning Weld-Metal Interface Enhance ISI capabilities for improved detection of service-induced flaws.
- 6.
Sizing Comply with intent some variations.
- 7.
Reporting of Results Compliance (one exception)
Page 3 Detailt of Alternative to Scanning Weld-Metal Interface The standard ASME Section XI beam angles (0, 45, 60) will be used to satisfy the requirement to examine the volume specified by the Code.
It is recognized that large planar type flaws reflect. and redirect a very narrow sound beam which directly influences detectability and sizing.
As the planar flaw size increases to a point where it exceeds the beam spread, the maximum range of misorientation for detection_ decreases.
As stated, examination techniques should be enhanced to optimize service-induced flaws.
Although we propose that 00,.450, and 60 angle beams be used, it is evident that modifications to current examination techniques will likely be required to examine the near surface area.
At this point, two techniques are being considered.
One involves the use of a 70 angle beam to examine the near surface area.
Alternately, a 450 full node examination may be capable of detecting near surface flaws.
Each of these techniques will be evaluated to determine which provides the best results and then implemented in the Oconee examination.
The 450 angle beam.is considered adequate for detection of flaws which initiate at the opposite surface at near right angles to the surface. Large flaws with a major axis oriented essentially perpendicular to the surface within the material volume are not expected to exist since the welds have been subjected to a radiographic examination per Section III requirements.
Details of Alternative to Sizing Recommendations The influence of flaw orientation on echo amplitude is signficant.
As such, data obtained from each beam angle must be compared to determine the flaw characteristics.
Low amplitude significant indications that occur within the volume between the near surface zone and the opposite surface zone will be investigated. If the comparison of the 00, 450, and 600 data indicates that the flaw is small, no additional data will be taken.
However, if the comparison indicates that the flaw may be large, an attempt will be made to orient the sound beam perpendicular to the major axis of the flaw. Once the major axis of the flaw has been determined, sizing will be based on the normalized angle.
MEETING
SUMMARY
DISTRIBUTION Licensee: Duke Power Company Copies also sent to those people on service (cc) list for subject plant(s)
Docket File-3 NRC PDR L PDR ORB#4 Rdg TNovak JStolz Project Manager Licensing Assistant OELD