ML20214T888
| ML20214T888 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 11/24/1986 |
| From: | Wilson R GENERAL PUBLIC UTILITIES CORP. |
| To: | Ebneter S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 5000-86-1085, IEB-79-02, IEB-79-14, IEB-79-2, NUDOCS 8612090043 | |
| Download: ML20214T888 (5) | |
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GPU Nuclear Corporation Nuclear
- en:r388 Forked River, New Jersey 08731-0388 November 24, 1986 609 971-4000 5000-86-1085 Writer's Direct Dial Nurnber:
Stewart D. Ebneter, U.S. Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406
Dear Mr. Ebneter:
Subject:
Oyster Creek Nuclear Generating Station Docket No. 50-219 Meeting Report 50-219/86-31 On September 16, 1986, GPU Nuclear met with the Region I staff to discuss progress on the present activities related to IE Bulletins 79-02 and 79-14.
The NRC docketed the minutes of that meeting in IE Meeting Report 50-219/86-31. The report directed GPUN to clarify five concerns raised by the staff at the meeting. Additionally, one unresolved item was opened in the meeting report.
Attachment I to this letter provides the requisite clarifications. The resolution of the unresolved item has been completed and is on file in the Oyster Creek Licensing Department, ready for NRC review and closecut.
If any further information is required, please contact Mr. John Rogers of my staff at (609)971-4893, truly yours, kE
. F. Wilson Vice President and Director Technical Functions RFW/JR/ dam:(0253A)
Attachment cc:
Dr. Thomas E. Murley, Administrator Region I U.S. Nuclear Regulatory Commission 631 Park Avenue f8d20 ggg eggggj King of Prussia, PA 19406 G
DDR Mr. Jack N. Donohew, Jr.
U.S. Nuclear Regulatory Commis;,fon 7920 Norfolk Avenue, Phillips Bldg.
Bethesda, MD 20014 I
NRC Resident Inspector Oyster Creek Nuclear Generating Station GPU Nuclear Corporation is a subsidiary of the General Public Utihties Corporation
[W O C
~J ATTACFMENT I "GPUN agreed to submit a : letter to clarify its schedular commitments for completion of activities related to IEB 79-02 and 79-14 and to discuss-other engineering issues raised during the meeting.
This submittal would provide:
Concern-An explanation and rationale for not inspecting supports on No. 1
_ some insulated piping systems and a commitment to perform the required inspection of the above supports when the piping insulation is removed."
Response: A total of 157 pipe supports within the scope of IE Bulletin 79-14 were not inspected below the insulation level. All 157 supports are outside of the drywell. Twenty computer models were utilized to analyze the piping affected by these 157 supports. Sixteen of these models meet original design, B31.1 stress allowables. The remaining 4
four. models satisfy ASME Section III Class 3 operability stress l
allowables (Level D) by wide margins.
i The extent of potentially undiscovered abnormalities which could only be identified by inspecting below the insulation levtl and which could cause a support to be evaluated as non-functional is small, based upon the existing inspection results for other outside 4
the drywell non-insulated pipe supports.
As presented in the meeting, there were 4 significant defects discovered on non-insulated pipe supports outside the drywell which would not have been identified if the piping were insulated at these support locations. These 4 significant defects, (which exclude the 4' Isolation Condenser missing clamp-to-shear-lug welds), result from an inspected population of 297 supports, yielding a 1.3% defect rate.
If this rate were applied to the 157 uninspected insulated population, only 2 additional non-functional supports would be
. expected..
As the piping models show wide operability margins and the projected number of additional non-functional supports is small, it can be concluded that inspecting the remaining supports below the insulation level is not recuired and the resulting potential impact on system operability is small and acceptable.
GPUN will not remove insulation on these 157 supports for the sole purpose of performing IE Bulletin 79-14 inspections. However, since these supports are also within the scope of the ISI Program covered by ASME III, when the supports and their pipe attachments are scheduled for an inservice inspection, the details of the below insulation attachments will be documented and reviewed for adecuacy.
. ~ _ _ _..
Concern "A safety evaluation addressing the use of Section III of the No.-2 ASME code for the qualification of the recirculation piping system in place of ANSI B31.1 as specified in the piping evaluation criteria."
Response: ANSI B31.1 Code,1983 edition was used to qualify the Recirculation piping system. Therefore, it was determined that the use of ASME
-Section III code for the qualification of the Recirculation system was not needed, hence, no safety evaluation of this concern is necessary. This action was taken subseauent to the September 16 meeting. The analyses of the Recirculation system, however, utilized the Systematic Evaluation Program (SEP) seismic response curves vice the original seismic design methodology. A safety evaluation has been performed to demonstrate the acceptability of utilizing the newer response curves.
Concern "An evaluation of the remaining pipe component nozzles and No. 3 penetrations to insure operability prior to the restart from the llR outage."
The evaluation of the remaining nozzles and penetrations has been completed. One hundred nozzles and penetrations have been evaluated and all were found to be acceptable based on operability criteria.
Concern "A detailed comparison of the licensee's current sampling plan No. 4 for anchor bolt verification to its original commitments in this regard. This comparison would address the number of supports included in each of the two plans and the criteria for upgrading supports."
Response: Shortly before the beginning of llR (February-March), it was necessary to define the scope of the anchor bolt inspections so the
(
job could be properly planned.
It was not known, in many cases, if a given support needed an upgrade, an inspection or both.
In spite of this however, all 324 baseplates included in 79-02 were either I
walked down or otherwise evaluated to determine their l
79-02 because of existing documentation.)ght to be excluded from accessibility.
(357 baseplates were thou At the conclusion of the walkdown,158 baseplates were identified for inclusion in llR. The list included baseplates considered inaccessible for inspection during operations but excluded those supports reauiring a structural upgrade. This number did include all baseplates which were known, j
at that time, to require an " anchor bolt only" upgrade ( 30).
I It was never GPU Nuclear's intent to commit to inspecting all 158 baseplates, but rather to inspect a sufficient number of baseplates i
to develop a level of confidence for the uninspected population.
It was determined that approximately 30% of the population (100 out of 324 baseplates) would need to be inspected to attain the requisite confidence level.
i' i
i l
-,_-_,,,--__,_.,.m
Seventy-three of the original 158 baseplates remain in the scope of the current refueling outage (11R).
Eighty-five of the original baseplates i
were removed from the llR work scope for the following reasons:
a) Factor of Safety 20 12 b) Inserts 20 c)QCdataavailable 5
d) Deleted from 79-02 program 10 e) Structural upgrades 29*
f) Deferred to 12R 9
- These 29 are made up of supports which had not been analyzed as of April 1, 1986, and a number (
- 10) of " anchor bolt only upgrades" which after further review required a structural change to the baseplate to accommodate the larger bolts.
During the course of the outage, 30 baseplates were added in order to keep the sanple size sufficiently large. They are categorized as follows:
a) Anchor bolt only upgrade 2*
b) Inspections / rework:
Factor of safety 2-3 8
Factor of safety 5 20*
- These 22 baseplates were either initially incorrectly judged to be accessible or added to the 79-02 program when documentation of the i
1979-1980 effort proved unsatisfactory.
In sunnary, GPUN has either inspected / reworked or upgraded 103 baseplates i
during llR which is 32% of the total number of baseplates requiring field work. Although the final work scope was somewhat different from that initially envisioned, the sample size is consistent with our original objectives.
Furthermore, the baseplates which were not in the original scope but added later, were all those having safety factors in the 2-3 range. We included these regardless of their accessibility during operations because they were judged to have the greatest potential for impact on safety. Regarding " anchor bolt only" upgrades, of the 32 baseplates which were included in the outage scope at one time or j
another, 20 baseplates were upgraded. Ten were deferred because it was recognized that the baseplates were too small to accommodate the higher l capability anchor bolt and therefore a structural change would have been j-necessary. One baseplate was deferred since it was judged to be accessible during operations, and one was deferred because consideration is'being given to removing that support from the 79-14 program by installing a new support closer to the containment boundary, i
Concern "A commitment for completion of cll Bulletin-related activities No. 5 including engineering evaluations dnd field modifications prior to the restart from the 12R outage,"
Response: As committed in our letter, Wilson to Murley, dated May 30, 1986, GPUN will assure that all systems within the scope of IE Bulletins 79-02 and 79-14 will meet original design criteria by the end of the i
cycle 12 refueling outage. Additionally, all engineering evaluations required to demonstrate that the identified systems meet the original design criteria will be completed at that time.
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