ML20023D438
| ML20023D438 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 05/13/1983 |
| From: | Fiedler P GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| REF-SSINS-6820 IEB-80-13, NUDOCS 8305200500 | |
| Download: ML20023D438 (13) | |
Text
s GPU Nuclear Q
g7 P.O. Box 388 Forked River, New Jersey 08731 609-693-6000 Writer's Direct Dial Number:
May 13, 1983 Regior +1 Mministrator Region I U. S. Nuclear Regulatory Cormnission 631 Park Avenue King of Prussia, PA 19406
Dear Sir:
Subj ect: Oyster Creek Nuclear Generating Station Docket No. 50-219 IE Bulletin 80-13 In accordance with the reqrirements stipulated in IE Bulletin 8F13,
" Cracking in Core Spray Spargers", we hereby submit GPUN Topical Report No. 013, Rev. O.
In addition, the attached report fulfills the unique reporting requirements of section 6.9.3(3)e of our Operating License and Technical Specifications.
If there are any questions, please contact me or Mr. J. Knubel of my staff at (201) 299-2264.
Very truly yours, JY LU t
P#ter'B. Fiedler Vice President and Director Oyster Creek l
l PBF:jal cc: Dire ctor l
Of fice of Inspection and Enforcement i
U. S. Nuclear Regulatory Commission Wa shing ton, D.C.
20555 NRC Resident Inspector Oyster Creek Nuclear Generating Station Forked River, NJ 08731 l
F305200500 830513 PDR ADOCK 05000219 0
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l GPU Nuclear is a part of the General Public Utilities System i
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OYSTER CREEK CORE SPRAY SYSTEM INSPECTION PROGRAM Response to NRC I&E Bulletin No. 30-13 Topical Report No.'013 (Rev. 0)
Project No. : 328023 R. A. Pinelli R. Jof fe AUTIlORS DATE May 3. 1983 PROVALS:
MLLwn ECTION MANAGER DATE i/ Lil73 e_
' DEPART}ENT' MANAGER DATE ACKu~~
.1-i-3{RE' R - QWALITY ASSURANCE DATE
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VICE PRESIDENT I DATE TECllNICAL FUNCTIONS (SIGNIFICANT IMPACT REVIEW) 1
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ABSTRACT During the 1983 refueling outage at Oyster Creek, an augmenced inspec-tion program was performed on the Core Spray System.
In-vessel annulus piping and sparger assemblies were examined using various combinations of remote visual, remote ultrasonic, and remote visual air testing techniques.
No relevant indications were identified or recorded. The reactor vessel internals are presently being examined (remote visual).
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t OYSTER CREEK CORE SPRAY SYSTEM INSPECTION PROGRAM INTRODUCTION The inspection program for the Core Spray Spargers at Oyster Creek has been developed and performed during the present 1983 refueling outage. The program and its results, as reported herein, are follow up responses to NRC I&E Bulletin No. 80-10 and Section 6.9.3(3)e (Table 4.3.1-9) " Unique Reporting Requirements" of Oyster Creek's Conditional Operating License.
i Both responses require the reporting of inspection results and plan of action, if needed, for the Core Spray Sparger System.
The inspections have been completed and a summary of each is presented below.
Visual Inspection of Core Spray Spargers, Annulus Piping, and Reactor Vessel Internals o
Core Spray Sparger Assemblies The Core Spray Sparger Assemblies were inepected to the same criteria, using the same methodology as that of the 1980 refueling outage (which was used as a baseline). Several areas showed indications which could not be characterized by the 1980 methods and subsequent close-ups were made and video enhanced (computer enhancement by Aptech, Inc.).
These tapes were compared with video enhancements of the 1980 tapes and finally determined to be irrelevant, i.e. surface markings in the crud layer. No relevant indications were identified or recorded.
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Core Spray Annulus Piping The Core Spray Annulus Piping was visually inspected with a fixture l
designed to be more stable giving a clearer video picture with less movement than that from the 1980 inspection.
No recordable indications were identified.
Visual Air Test of System II Sparger and 6" Vertical Annulus Piping o
This limited test was performed to detect through-wall cracks in the 6" vertical inlet piping (annulus) and the upper sparger arm assemblies as indicated by air bubbles passing through the crack.
No such tell-tale bubbling was noted except at the repair bracket at 208' which is the location of the through-wall crack identified and repaired in 1978.
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o Reactor Vessel Internals Remote visual inspection of reactor vessel internals is scheduled fol-lowing the completion of fuel off-load.
E Ultrasonic Inspections of the Core Spray Sparger & Annulus Piping d
Ultrasenie Inspection of Sparger Assemblies o
This inspection was performed using a Harisonics designed fixture simi-lar to that used in 1980. The area suspected, however, was that inspected in 1980 minus those areas on both systems not accessible due to the nine additional repair brackets installed in 1980.
No recordable indications were identified.
Ultrasonic Inspection of Annulus Piping o
Seven (7) welds were inspected on the' core spray piping in the vessel annulus. Piping configuration and vessel component / instrumentation obstructions led to inaccessibility of any additional inspections.
How-ever, of the welds which were examined, three (3) were analyzed as having the highest sustained stresses.
Two (2) were analyzed as having the next highest sustained stresses and two (2) were in the next lower category. No recordable indications were identified in any of the seven i
welds inspected. The recording criteria (20% through-wall) was based on an allowable percent through-wall crack determined from a crack growth analysis for an additional operating cycle.
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NETHODS AND RESULTS Internal Visual Examination of Core Spray System l
The visual examination of the core spray spargers was performed using techniques similar to those employed during the 1980 inspection.
This year visual examinations were performed prior to the ultrasonic i
examination which enabled examination of a smooth undisturbed surface unlike the surface found in 1980 which was marred by the ultrasonic fixture and
-teoling prior to visual inspection.
The core spray annulus piping was examined with improved fixturing which enabled examination of a greater volume of piping while maintaining a stable picture capable of being enhanced.
l These visual inspections were performed by CTS Power Services with all
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of the results being evaluated by a GPUN certified examiner.
l Any indications that were detected were enhanced with an on-line com-puter and video processor supplied by Aptech Imaging Inc. By doing the
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anhancement while on-line, a determination could be made relative to signal strength necessary for enhancement, correct camera angle, etc.
Any indications that were detected during a more thorough review of the tapes af terwards were enhanced from the video-tape made during the inspection.
Three areas from the 1980 inspection; 112*,183
- and 185
- on System II were visual indications that were not clamped. These areas were examined closely using a hand held camera rig which permitted much closer viewing of the pipe surface.
These three areas were also enhanced to show if the 1980 indications could be seen. All of these System II examinations revealed no indications.
One area on System I at 251' through 255* is an unclamped 1980 visual indication.
This area was closely examined and revealed no evidence of the-previous indication. Also closely examined were the areas adjacent to the repair clamps.
There was no evidence of the 1980 indications found at any of these locations.
Visual Air Test When the visual examinations were completed, an air test was performed on System II.
System II spargers were examined with the only evidence of bubbling coming from the 1978 repair clamp at azimuth 208*.
The only System II annulus piping that could be inspected was from the vessel penetration to the annulus coupling on the 6 inch downcomer.
The horizontal piping in the annulus could not be inspected because the bubbling from the spargers recircu-lated into the annulus area before they dispersed.
Because of this recircu-lation probicm there was a multitude of bubbling coming into the annulus No air test was performed on System I due to constraints of piping con-a re a.
figuration and sparger nozzle location.
In conclusion, based upon the examination technique, the image enhance-ment proces s, and the air test there were no recordable indications found de ing this inspection.
Ultrasonic Examination of Core Spray Spargers Ultrasonic examination of the Core Spray Spargers was performed using techniques similar to that employed during the 1980 inspection ef fort.
The fixture used was improved to provide better shoe to pipe contact.
The examination was performed by qualified NDE personnel under the supervision of GPUN Site Quality Control personnel. The areas examined are shown on Fig. 1.
Of the indications detected in 1980 only five areas were not covered with repair clamps.
These areas were on System II at azimuths 13*/14*,
102*/103*, 183 */18 5*, 220*, and 322*.
No indications were detected in these areas during this inspection effort.
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Midway through the scan the bottom shoe of the fixture broke loose pro-hibiting examination of approximately half of the accessible portion of the System One sparger using the-helical technique.
To summarize, significantly less of the surface area was scanned than 1980 because of the number of repair clamps placed on the sparger. Of the areas that were scanned, no recordable indications were detr,cted.
Oyster Creek Internal Core Spray Piping Ultrasonic Examinations During the period of March 11, 1983 to March 18, 1983, ultrasonic examiners from the General Electric Company examined piping welds (Figs. 2&
- 3) associated with the Core Spray Annulus Piping. A synopsis of the 14 examinations attempted and performed is as follows:
6" Horizontal Piping o
Weld U7 263* of the accessible portion of the weld and heat 4
affected zone was examined, with no recordable indications -
noted.
Weld L7 305* of the accessible portion of the weld and heat affected zone was examined, with no recordable-indications noted.
Weld L14 No attempt to examine this weld was made because of the space limitation discovered while trying to examine weld L15.
5" Horizontal Piping o
Weld L8 293* of the accessible portion of the weld and heat affected zone was examined, with no recordable indications noted.
Weld L9 301* of the accessible portion of the weld and heat affected zone was examined, with no recordable indications noted.
Weld L15 No access, UT fixture would not clear between the pipe and the RPV wall.
Pipe or shroud is out of round at this point.
Weld L16 No access, vibration instrumentation lines prevented UT fixture access.
Weld U9 No access, vibration instrumentation lines prevented UT fixture access.
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t Weld U8 Examined 336' of the accessible portion of the weld and haat af fected zone, with no recordable indications noted.
2 Weld U17 Examined 295* of the accessible portion of the weld and heat.af fected zone, with no recordable indications noted.
g Weld U18 Examined 286.5* of the accessible ' portion of the weld and heat af fected zone, with no recordable indications noted.
o 16" Vertical Piping
.4 Wcld US No access, could not get UT fixture past the shroud lug.
Weld L5 No access, UT fixture pole hits spool piece at Wald L3A, 1
preventing proper positioning of the clamp.
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o 5" Vertical Piping Weld L11 No examination performed -- the scanning ring came loose from the UT device while attempting to examine this weld and become wedged' between the two 5" vertical pipes.
During the examinations performed, only OD weld crown indications were noted. UT signal amplitudes from the se weld crown indications were less ' tha n
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the recording criteria, as stated in G.E. Procedure TP508.1016 "0yster Creek Internal Core Spray-Piping U.T. Inspection Device" (Ref.1) and GPUN TDR #403
( Ref. 2).
CONCLUSIONS OF INSPECTIONS Following the completion of all inspections relative to the Core Spray System, a review was conducted of the results along with the 1978/1980 in'spe c-i tion re sults and selected video tape enhancements performed in 1982. The following are conclusions drawn from this review.
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The number of confirmed cracks in the sparger assemblies is one, tha t being the through-wall crack at 208' identified and clamped in 1978.
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The 1982 video enhancement of the 1980 inspection tapes greatly reduced the number 'of potential cracks observed (Table 1).
Of the th ree (3) potential cracks remaining, one remains unclamped and from the 1983 inspection results, no indication could be identified at that location.
It is concluded that this previously identified indication is not a 4
crack.
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Evaluating the 1983 inspection results, and the 1980 video tape l
enha rceme nts (clamped a nd u nclamped areas), and the results of the air tests, there are no indications of growth of previously identified defects.
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a The 1983 UT incpection of the sparger arm assemblie s, showed no record-o able indications.
Considering the improved 1983 techniques, we conclude tha t the 1980 reported UT results are highly su spect.
In summary, all 1983 examinations of the sparger assemblies revealed no o
indications, except for the reported 1978 crack.
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4 Addressing the remaining 1980 indications (11 UT and 2 visual) which cannot be inspected due to clamp installation, our judgment, based on the resulta of the inspections which were performed, is that there are no visual or UT indications, actually present.
Furthermore, no evidence of growth exists based on the visual inspections at the edge of the clamps and the air test on System II.
Finally with the repair clamps installed, the structural integrity of the assemblies is adequate and judged not to be a concern.
Based on the video enhancements of 1980 tapes and the large reduction in o
the number of potential cracks observed, the structural integrity of the sparger arm assemblies is believed to be in a much better condition than that presented in 1980 and approved for cperation, Both visual and UT inspections of the annulus piping confirm the lack of o
any indications and it is concluded that no cracks of structural signi-ficance exist in this inlet piping and that the piping is structurally capable of meeting its design function.
REFERE NCES 1
1.
General Electric Procedure TP508.1016, "0yster Creek Internal core Spray Piping U.T. Inspection Device" 2.
GPUN Technical Data Report #403, "0yster Creek Core Spray Sparger Annulus Piping Stres s Analysis"
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n TABLE 1 1,
CORE SPRAY PIPING INSPECTION
SUMMARY
S p a r g e r s Annu1us Piping Visual Ultrasonic Visual 111trasonic Air Test Remarks One Repair Bracket 1978 1 through No indications Air release obserged installed at 208 wall crack from 1 crack (208 )
(g, 77) only Seven Repair 1980 19 indica-16 indications 2 indications tions called Brackets Installed cracks (Sys II)
Two Repair Brack-28 Total Indications (excluding ets installed 1978 indication)
(Sys I) 1982 Video enhanced Video enhanced Video 1980 visual in-one 1980 indi-Enhance-dications, cation ments Results identi-Results:
fied:
Not a crack 3 cracks (6 x 5 reducer) 2 possible cracks 1983 No indications No indications No indications No indications
- Area of Inspections (4 of 1980 (5 of 16 - 1980 7 welds limited by Repair indications indications inspected Brackets examined) rechecked)
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