ML20033G847
| ML20033G847 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 03/31/1990 |
| From: | Bates R, Lakner A VIKING SYSTEMS INTERNATIONAL |
| To: | NRC |
| Shared Package | |
| ML20033G848 | List: |
| References | |
| CON-NRC-03-87-028, CON-NRC-3-87-28 GL-88-01, GL-88-1, NUDOCS 9004120209 | |
| Download: ML20033G847 (53) | |
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ai TECHNICAL EVALUATION REPORT ON l.
RESPONSE.FROM J[
GPU NUCLEAR CORPORATION =
70 GENERIC LETTER 88-01~
PERTAINING TO THE l
OYSTER CREEK NUCLEAR GENERATING PLANT -
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Johnstown, Ohio Pittsburgh, Pennsylvania Washington, D.C.
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FINAL.
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TECHNICAL EVALUATION REPORT ON-
.j RESPONSE FROM 1
GPU NUCLEAR CORPORATION-1D GENERIC LETTER 88-01 PERTAINING-TO THE OYSTER. CREEK NUCLEAR GENERATING PLANT:
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-l Published March, 1990-j
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1 prepared by Robert C. Bates-Armand Lakner -
I Viking Systems International 4
2070 Wm. Pitt Way k3j,5Q Pittsburgh, PA Prepared for:
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U.S.Nu$1earRegulatoryCommission l
Washington, D. C. 20555-j.
under
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Contract No. NRC-03-87-028, Task Order 005' l
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ABSTRACT f
This report contains an evaluation of the licensee (GPU Nuclear Corporation) submittal for Oyster Creek Nuclear Generating Station which was submitted in response to the NRC Generic Letter 88-01 in which GPUN was requested to (1) Furnish their current plans relating I
to piping replacement and other measures to mitigate IGSCC, inspection,
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repair, and leakage detection.
(2) Indicate whether they plan to follow f
the NRC Staff positions, or propose alternative measures.
GPUN's plans f
1,i are evaluated in Section 2 of this report in terms of-compliance to NRC Staff positions.
Section 3 contains an evaluation of Alternative
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Positions concerning inspection of portions of the RWCU, inspection ol' stress-improved welds, and changing the Technical Specification l'J, on ISI.
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1 SIMRRY l
j The Licensee, GPU Nuclear Corporation, submitted a response to the
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NRC Generic Letter 88-01. GPUN's response pertaining to the austenitic i
stainless steel piping in the Oyster Creek Nuclear Generating Station 3
(a BWR nuclear power plant) was evaluated in terms of (1) Their previous and planned actions to mitigate IGSCC to provide assurance
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of continued long-ters service.
(2) Their Inservice Inspection (ISI)-
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(3) Their Technical Specifications pertaining to ISI and
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their plans to ensure that leakage detection will be in conformance with the NRC Staff position.
(4) Their plans to notify the NRC of'
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significant flaws identified (or changes in the. condition of the welds previously known to be cracked) during inspection and evaluation of such flaws.
GPUN accepts cnd endorses 7 of the 13 NRC Staff positions which are outlined in Generic Letter 88-01, accepts 5 others with provisions l
(some acceptable, some unacceptable), and did not indicate acceptance /
rejection of one, GPUN has utilized several of the recommended mitigating actions including partial replacement, stress improvement, and weld overlays. They plan additional piping replacement and stress l
improvement treatments.
In addition GPUN plans to implement HWC.
GPUN performed inspections during Refueling Outages No. 11 and No.
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12 that conform with current NRC Staff positions on methods and j
personnel. They presented inspection schedules for Refueling Outages l.
No. 13 and No. 14. Their schedules incorporate reductions in frequency l
of inspections due to implementation of HWC. They also incorporate i
reductions due to an alternate position on inspection of welds of certain IGSCC Classifications.
l GPUN presented alternative positions concerning inspection of portions of the RWCU, inspection of stress-improved welds, and changing the IS on ISI. These positions are evaluated in Section 3 of this report.
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e CO N m
i ABSTRACT i
SUMMARY
11 1.
INTRODUCTION 1
2.
EVALUATION OF RESPONSE TO GENERIC LETTER 88-01 2
2.1 Documents Evaluated 2'
l 2.2 Review of OPUN's Responses to Staff Positions 4
and Implementation of 'Ihose Positions d
2.2.1 Conclusion of GPUN's Responses to NRC 4
Staff Positions 1
2.3 GPUN's Examination Schedule 6
2.4 Review of GPUN's Previous Inspection Program, Previous 7
Mitigating Actions, and Current Classification of Welds g
2.4.1 Current IGSCC Classifications and Number of Welds 7
2.4.2 Previous and Current Inspection Programs 7
4 c-2.4.3 GPUN's Proposed Acceptance of 1983/84 and 11 1986 Inspections 2.4.4 Stress Improvement 12 q
2.4.5 Weld Overlays 13 2.4.6 Water Chemistry 14 2.4.7 Evaluation and Recommendations 14 2.5 Current Plans for Mitigating Actions 15 2.5.1 Hydrogen Water Chemistry 15 2.5.2 Piping Replacement 18 2.5.3 Stress Improvement 18 2.5.4 Plans for Un.inspectable Welds 20 iii
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2.5.5 Expected IGSCC Qassifications of Welds 20 (Following Refueling Outege112) 2.5.6 Evaluation of Conformance to Staff Positions 21 and Recommendation i
p 2.6 Plans for Future Inspections 23 i
2.6.1 Summary of Inspection Schedules
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2.6.2 GPUN's Positions 24 1
a 2.63 Sample Expansion 25 _
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2.6.4 Evaluation of GPUN's Positions and Inspection Schedules 26 j
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2.7 Changes fri the Technical Speci5 cation Concerning ISI 28 2.8 Confirmation of Leak Detection in the Technical Specification 29 2.8.1 Conformance with Position C of Regulatory Guide 1.45 29 2.8.2 Other Leak Detection Requigements 30 2.83 Evaluation and Recommendation 33 2.9 Plans for Notification of the NRC of Flaws 33 2.9.1 GPUN's Position 33 l'
2.9.2 Evaluation and Recom:nendation 33 l
3.
ALTERNATIVE POSITIONS 34 GPUN's Alternate Position Concerning Welds in the RWCU 34 I
3.1 l
L 3.1.1 GPUN's Position 34 3.1.2 Evaluation and Recommendation 38 3.2 GPUN's Alternate Position Concerning ISI in the 39 j
Technical Specification
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l 3.2.1 GPUN's Position 39 3.2.2 ' Evaluation and Recommendation 40
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33 GPUN's Alternate Position Concerning Inspections of 40 Stress-Improved Welds l
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33.2 GPUN's Position 41 I
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333 Evaluation and Recommendations 41-i b;
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CONCLUSIONS AND RECOMMENDATIONS 42 i
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5.
REFERENCES 46 lc, h
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- 1. Il(TRODUCTION i
- 1. 2 Intergranular stress corrosion cracking (IGSCC) near veldsents in j
Boiling Water Reactor (BWR) piping has been occurring for almost 20-i years.. Substantial efforts in research and development have-been-sponsored by the BWR Owners Group for IGSCC Research,.and the'results j
of this program, along with other related work by vendors, consulting.
firms and confirmatory research sponsored by the NRC, have permitted 1
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$a the development of NRC Staff positions regarding the IGSCC problems.
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The technical basis for NRC Staff positions is detailed in Reference 1, and further background is provided in Reference'2.
The results of these research and development programs prompted the NRC to issue Generic Letter 88-01 (see Reference 3) requesting all l
licensees of BWR's and holders of construction permits tot j
(1) Furnish their current plans relating to piping replacement, i
j inspection, repair, and leakage detection.
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(2) Indicate whether they j
(a) Plan to follow the staff positions, or (b) Propose alternative measures.
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Specifically, Generic Letter 88-01 stated that an acceptable licensee response would include the following items 4
(1) Current plans regarding pipe replacement and/or other measures taken or to be taken to mitigate IGSCC and provide assurance of continued long-term piping integrity and reliability.'
(2) An inservice inspection (ISI) program to be implemented at-J
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the next refueling outage for austenitic stainless steel piping.
(3) A change to the Technical Specifications to include a statement 2
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i in the section on ISI that the inservice inspection progran for piping will be in conformance with the staff positions on scheduls, methods and personnel, and sample expansion.
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I (4) Confirmation of plans to ensure that the Technical Specification related to leakage detection will be in conformance with the n
Staff position on' leak detection.
l (5) Plans to notify the NRC, in accordance with 10CFR50.55a(o),of any flaws identified that do not meet IWB3500 criteria of, I
Section II of the ASME Code for continued operation without l
evaluation, or a change found'in the condition of the welds previously known to be cracked, and an evaluation of the flaws l
for continued operation and/or repair plans.
This report contains a technical evaluation of the response which GPU Nuclear Corporation (hereafter called GPUN) submitted in response to -
I the NRC Generic Letter 88-01 pertaining to the Oyster Creek Nuclear Generating Station (hereafter called Oyster Creek).
- 2. EVALUATION OF RESPONSE TO GENERIC LETTER 88-01 p
This evaluation consisted of a review of the response to NRC Generic Letter 88-01 of January 25, 1988 by GPUN pertaining to Oyster Creak to determine if their performance and plans are in conformance with
.l the NRC Staff positions or if proposed alternatives are acceptable.
Proposed inspection schedules and amendments to the Technical i
Specification were included in the review.
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2.1 Documents Evaluated i
Review was conducted on the information pertaining to Oyster Creek c
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i provided by the Licensee in the following documents.
(1) "0yster Creek Nuclear Generating Station (OCNGS), Docket No. 50-219. Response to Generic Letter 88-01," GPU Nuclear
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Corporation, One Upper Pond Road, Parsippany, New Jersey 07054, August 12, 1988.
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(2) "0yster Creek Nuclear Generating Station (OCNGS) Docket No. 50-219 IGSCC Inspection Plan - RWCU," GPU Nuclear u
. Corporation, One Upper Pond Road, Parsippany, New Jersey
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07054 November 16, 1989.
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i (3) "0yster Creek Nuclear Generating Station (OCNGS), Docket No. 50-219, (Revised Response to Generic Letter 88-01),"
GPU Nuclear Corporation, One, Upper Pond Road, Parsippany, i
a New Jersey 07054, January 31, 1989.
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(4) "0yster Creek Nuclear. Generating Station (OCNGS). Docket
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No. 50-219, IGSCC Inspection Plan - RWCU, GPU Nuclear j
Corporation, One Upper Pond Road, Parsippany, New Jersey j
07054, February 21, 1990.
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Hereafter, in this report, these documents will be referred to as GPUN i
Submittals No. 1, No. 2, No. 3, and No. 4, respectively, and
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collectively as the GPUN Submittals.
l Note that GPUN Submittal No. I was prepared in August, 1988 (about c
one and one-half years ago).
At that time, Refueling Outages No. 10 and No. 11 were completed, while Refueling Outages No. 12 and No. 13 s
were still in the future (scheduled for 1988 and 1989, respectively) -
r; and GPUN's plans as reported in GPUN Submittal-No. 1 reflect the status at the completion of Refueling Outage No. 12. GPUN Submittal No. 3 is a revision of GPUN Submittal No. I and was prepared prior to
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Refueling Outage No. 13 (scheduled for 1989). This report, therefore, 3
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i which is based primarily on GPUN Submittals No. I and No. 3 (GPUN G
Submittals No. 4 is an updating of CPUN Submittal No. 2 and these U
submittals deal only with the portion of the RWCU that is outboard of the containment isolation valve), treats Refueling Outage No.13 j
j as a future outage and the refueling outages prior to that as past
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outages.
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O 2.2 Review of CPUN's h sponses to Staff Positions and Implementation of Those Positions.
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l The GPUN Submittals did not specifically state acceptance or:
rejection of the 13 NRC Staff positions pertaining to materials,-
j processes, water chemistry, weld overlay, partial replacement,
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stress improvement of cracked weldsents, clamping devices, crack
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l evaluation and repair criteria, inspection methods and personnel, inspection schedules, sample expansion, leak detection, and reporting requirements. However, the GPUN positions on most of j
these items were implied.in discussions in the GPUN Submittal No.
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1, and these positions are presented in Table 1.
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l-2.2.1 Conclusion on GPUN's Responses to NRC Staff Positions An examination of Table 1 shows that GPUN indicated acceptance of seven of the 13 NRC Staff positions, acceptance with l
provirions of five of the 13 hRC Staff positions, and did not indicate endorsement / rejection of one of the NRC' Staff positions-l t
(i.e., clamping devices). Additionally, GPUN Submittal No.
1 interpreted the scope of Generic Letter 88-01 to exclude the welds in the RWCU that are outboard of isolation valves.
Although this interpretation was altered in GPUN Submittal No.
3, an alternative position concerning inspection of those welds is presented in GPUN Submittal No. 3.
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l Table 1 Summary of GPUN's Responses to Staff Positions j
GPUN Accepts GPUN Has/ Will NRC Staff Applied Consider for fi Staff Position Position In Past Future Use
- 1. Materials yed
'yes yes
- 2. Processes yes yes yes
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no(*)
yes(*)
- 3. Water Chemistry yes
- 4. Weld Overlay yes yes NI
- 5. Partial Repiscement yes yes yes
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- 6. Stress Improvement of Crscked Weldments yes(b) yes(b) yes
- 7. Clamping Devices NI N1 NI
- 8. Crack Evaluation and Repair Criteria yes' yes yes
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- 9. Inspection Method and Personnel yes(c) see (c) yes
- 10. Inspection Schedule yes(d) see (d) yes(d) f f
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11.-Sample Expansion yes(b) 7,,(b)
- 12. Leak Detection yes(b) 7,,(b) l
- 13. Reporting Requirements
-yes(b) 7,,(b)
(a) Implemented improvements in water chemistry beginning in 1984.
HWC scheduled for impler&.tation following R.O. No. 12.
(b) Provisions applied.
See later discussion.
(c) Current methods and personnel qualified per NUREG 0313, Rev. 2, but GPUN claims inspection methods.and personnel were also i
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qualified since 1983, but in their latest submittal they did not
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claim credit for those inspections.
(d) Applies 50% credit for HWC, and has reduced schedule on selected
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welds. GPUN presented an alternative proposal concerning.
4 inspection of welds in RWCU that is outboard'of the second i
isolation valve.
In addition, GPUN proposed statement that of compliance with Generic Letter 88-01 should be included in the Inservice Inspection Program rather than in the Technical Specification.
NI Not indicated.
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L 2.3 GPUN's Examination Schedule l
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The year (but not month within the year) of each of four refueling h
outages was listed in GPUN Submittal No. 1.
These outages are
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listed in Table 2 of this report.
Note that all of these 3
-inspections have already occurred, although the results of Refueling Outage No. 13 were not reported in the GPUN Submittals. The dates of Refueling Outages beyond that of Refuelin's Outage No. 13 were u
not disclosed in the GPUN Submittals.
m Table 2 Dates of Refueling. Outages l^
t Outane Year
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Refueling Outage # 10 1983/84 RefuelinE Outage # 11 1986 Refueling Outage l'12 1988 Refueling Outage # 13 1989 1
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2.4 Review of GPUN's Previous Inspection Program. Previous
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Mitimatina Actions and Current Classification of Welds J
GPUN Submittal No. I and GPUN Submittal No. 3 e.ch list a total
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of 473 welds that are covered in the scope of NUREG 0313, Revision 2 and Generic Letter 88-01. Of these, according to GPUN Submittal No. 3, 26 are uninspectable and cre not discussed in this section l
(see Section 2.5.4 for a discusvilon of uninspectable welds).
According to GPUN Submittal No. 1, 54 welds were uninspectable prior to actions taken during Refueling Outage No. 12.
Previous i
actions include inspections, application of IHSI (induction heating I
j stress improvement, repair of cracked welds with overlays, partial y
replacement, and improvement of water chemistry. These actions
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are discussed in greater detail in the following sections.
f 2.4.1 Current ICSCC Classifications and Number of Welds i
l The 473 welds are divided among six piping systems as shown F
in Tables 3 through 5.
The current number of welds (actually
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the number following Refueling Outage No. 12) classified b.
in each IGSCC category is contained in GPUN Submittal No.
3 along with plans for inspections during future refueling outages. These classifications and inspection plans are discussed in 1cter sections of thit. ;. port.
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2.4.2 Previous and Current Inspection Programs l
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A total of 190 welds were examined during the 1983/84 outage i
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(Refueling Outage No. 10).
During Refueling Outage No. 11, I
a total of 166 welds were examined.
During Refueling Outage i
No. 12, a total of 142 welds were examined. Summaries of those inspections, showing the-number of welds examined and the number of cracks found in each system, is contained in l
Tables 3, 4, and 5.
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L Ta' ole 3 I
H Summary of 1983 (Refueling Outage'# 10) and 1984 j
Inspections and Mitigating Actions (a,b)
(from GPUN Submittal'No. 1) 2 l
4 l,
No. of Number No. of System Welds Insect. Cracks Nutinatina Actions l
Recir.
64-31 0
j CS 22 3
0 l
SDC 14 2
0 RWCU 142 8
0 10-1 40 19 0
10-2 129 127 28(c) Repair cracked welds (0.L. 18, replace 9 with spool piece change out)
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Totals 419 190 28 i
-i Notes:
(a) This table does not include 54 un-inspectable welds.
(b) The numbers in Qis column were obtained from Sections 1.2.1 and 2 of GPUN Submittal No. 1.
Numbers reported in Table 3 of GPUN
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7 Subsittal No. 1 are slightly different.
(c) One crack indication was originally inttrpreted as a root geometry
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indication and re-interpreted when that veld was re-examined during
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R.O. # 11.
Explanation or abbreviations f
i Recir. Recirculation System CS Core Spray System SDC Shutdown Cooling System RWCU Reactor Water Clean-Up System 10-1 Isolation Condenser System - inside drywell
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10-2 Isolation Condenser System - outside drywell CH Closure Head Welds f
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1 Table 4' I
m Summary of 1986 (Refueling Outage i 11) Inspections and Mitigating Actions (a,b) (From GPUN Submittal No. 1) i
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'l Number No. of.
i System Welds Insect. Cracks Mitimatina Actions' Recir.
64 64(*)
2 of 3 cracks repaired with 0.L.
1 CS 22 16(*)
0 SDC 14 6(')
O L-RWCU 142 10(')
0 10-1 40 12(*)
0 I0-2 129 58(d) 1(f) Crack repaired with 0.L..
CH 8
0 0
Total 419 166 4
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Notes (a) This table does not include 54 un-inspectable welds.
(b) Numbers in this table were obtai.ud from Table 4 and Sections.
1.2.1 and 2 of GPUN Submittal No. 1.
Numbers reported elsewhere-1 in Section 1.2.1 and Table 3 in GPUN Submittal No. I are slightly j
different.
(c) Inspections were performed following IHSI treatments.
(d) Includes overlayed welds and un-repaired cracked' weld.
(e) Includes 2 CS, 2 SDC, 2 RWCU, and 4 10-1 previously inspected welds.
(f) Same indication that was mis-interpreted during R.O. # 10.,
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Explanation of abbreviations Recir Recirculation System CS Core Spray System SDC Shutdown Cooling System K
RWCU Reactor Water Clean-Up System Il IC-1 Isolation Condenser System - inside drywell IC-2 Isolation Condenser System outside drywell-CH Closure Head Welds 9
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-Table 5 7
Summary of 1988 (Refueling Outage # 12) Inspections and j
Mitigating Actions (From G.?UN Submittal No. 3)
Number No. of System Welds Inspet. Cracks Kittaatina Actions Recir.
89(*)
67(b) 3 Machine C-loop' safe-ends, SI, inspect.
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SI on 23 g de - includes 4 welds on 2 CS 26 9
0 safe-ends
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SDC 14 3
0 I
RWCU 147(d) 10 0
IC 189(*)
l SI on 14 g ds - includes 4 welds on 2 (In Containment) li 0
safe-ends (Outsite Cont.)
37 3
0 L of 3 cracked welds.
CH 8
2 0
Total 473 142 6
i Notes (a) Includes 5 uninspectable casting-to-casting welds.
(b) Includes three cracked welds.
Initial inspection of 6 IGSCC Category welds revealed two cracks. Sample expansion of an additional 6 welds revealed one crack.
Inspection sample then' expanded to all IGSCC Category C welds.
Post-SI inspections of safe-ends not included
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in this total.
(c) Post-SI inspections applied to safe-end welds and.a sampling of other welds.
('d) Includes 5 uninspectable welds inside penetrations.
(e) Isolation Condensor contains 16 uninspectable welds: 8 welds inside penetrations, 4 flued head-to-valve welds, 2 casting-to-casting welds, 2 saddle welds.
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l Explanation of abbreviations L
Recir. Recirculation System CS
. Core Spray System SDC Shutdown Cooling System RWCU Reactor Water Clean-Up System IC Isolation Condenser System CH Closure Head Welds j
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4 2.4.3 GNUP's Proposed Acceptance of 1983/84 4.
h and 1986 Inspections i
i The 1986 inspections were performed by GE using manual and
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FI automated techniques. Both the procedures and personnel qualified at the EPRI Center under the NRC/BWROG/EPRI j
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'J Coordinati>n Plan.
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GPUN Submittal No. I claims that procedures and personnel used for'the 1983/84 inspections were also qualified and
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that those inspections should be accepted for purposes of classifying. welds into the'various IGSCC categories and developing their future inspection programs. The basis of
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this claim, as stated in GPUN Submittal No. 1, is summarized below.
i s The 1983/84 inspections were performed by Magnaflux personnel 2
(qualified.at Battelle Columbus Laboratories) using manual techniques.(also qualified'at Battelle Columbus Laboratories j
and further qualified to the procedure on site at Oyster y
Creek).
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'. i A table which compares some aspects of the two techniques L.
was included in the GPUN Submittal No. 1.
Search units of s
45' and 60' were used in both tests,-but different search speeds and search unit overlap were different in the two f
l tests as shown below.
Maximum Minimum Search Search Speed Unit Overlao 1983/84 6 in./sec 25%
1986 3 in./sec 50%
GPUN stated that even thcugh the 1983/84 and 1986 techniques
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. were not identical, the results were consistent and that i
98% of the repeated examinations from 1983/84,were confirmed during 1986 as not having IGSOC indications.
In addition, GPUN claimed that the results of inspections in 1983/84 were conservatively interpreted so that in cases where NDE could i
not clearly distinguish between IGSCC cracks and geometric i
causes, they conservatively interpreted the indications to
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be caused by cracks.
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T To support these claims, GPUN presented a. table which compares H
the results of 97 inspections in 1983/84 that were repeated in 1986 to illustrate this claim. Cracks were reported in a
1983/84 in 18 of the 97 welds inspected. Since these welds were repaired with weld overlays, a comparison of 1983/84 f
and 1986 inspection results is not possible.
Of the remaining i
79 welds, 77 were reported as un-cracked in both inspections..
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Two welds (NG-C-23 and NE-1-27) were reported as un-cracked.
in 1983/84 and cracked in 1986, although the GPUN Submittal No. I stated that indications were found in 1983/84 that I-were attributed to root geometry in those two welds.
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Subsequently, following conversations with the NRC Staff, GPUN withdrew its request to take credit for inspections performed prior to Refueling Outage No. 11.
(See page 16 of GPUN Submittal No. 3).
2.4,4 Stress Improvement, t
During Refueling Outage No. 11, the 64 inspectable welds l
L in the Recirculation System were stress improved using the induction heating stress improvement (IHSI) process.
All 1
64 welds were inspected following the stress improvement.
r During Refueling Outage No. 12, the C-loop safe-ends in 4
12 J
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t the Recirculation System were machined and Stress Improved.
r, In addition, Stress Improvement Treatments were applied to b
24 welds in the Core Spray System (including 4 welds on 2 safe-ends) and 14 welds in the Isolation Condenser System (including 4 welds on 2 safe-ends).
Post-treatment f
inspections were applied to all of the safe end-welds that were treated with Stress Improvement, but only a aanpling of the other SI-treated welds were given post-treatment-inspections. GPUN's position on inspection of Stress Improved
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welds is discussed in Section 3.3 of this report.
r+4 2.4.5 yeld Overlays During the 1984 inspection of 127 welds in the Isolation Condenser (performed because a leak occurred in that system),
l 28 indications were found. One of the indications was incorrectly interpreted as.a root-geometry indication. The other 27 were repaired: 'nine of the 27 were replaced through
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spool change out, and 18 of the 27 were repaired with full structural weld overlays.
During the Refueling Outage No.
th 11 inspection, it was determined that the 28 indication.
was caused by a crack rather than root geometry and it was repaired with a full structural weld overlay.
As mentioned above, the 64 stress improved welds in the Recirculation System were inspected following the IHSI l
treatments. Three cracks were found during those inspections.
Two of these were repaired using full structural weld overlays. The other was evaluated (using the approach I
recommended in NUREG 0313, Revision 3, in draft form at that time ), and it was determined that crack did not need to l-be repaired at that time.
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I' During Refueling Outage No. 12, inspections revealed 13
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cracks in three welds in the portion of the Isolation Condenser System outside of containment.
One of these had j
been previously inspected (during Refueling Outage No. 11),
and the other two had not been previously inspected. Weld overlays were applied to repair the three cracked welds.
2.4.6 Water Chemistry l
?
GPUN has taken a number of actices at Oyster Creek to improve water chemistry including implementation of EPRI water s
chemistry guidelines, establishment of a new chemistry 7,
y Laboratory with state-of-the-art equipment for analyses, and plugging a large number of leaking condenser tubes (no condenser tube leaks were found in the.next refueling outage).-
These efforts resulted in substantial improvements in water conductivity.
I-2.4.7 Evaluation and Recommendations A considerable number of mitigating treatments have been f
f applied at Oyster Creek by GPUN. Most of these treatments have followed guidelines presented in Generic Letter 88-01.
l The exceptions consist of several welds that were treated with Stress Improvement. Although these treatments were j
in compiance with recommendations of Generic Letter 88-01,
[
several of these welds were not given post-treatment f
inspections. GPUN's position regarding these treatments
{
is discussed in Section 3.3 of this report.
i Guidelines presented in Section 5.2.1 of NUREG 0313, Revision
[
i 2 state that inspections performed after September, 1985 in conformance with the NRC/BWROC/EPRI Coordination Plan I
~
are acceptable.
Since the 1986 inspections at Oyster Creek vere qualified in accordance with those guidelines, acceptance 14 i
J J
4 E
of the 1986 (Refueling Outage No. 11) is recommended.
j On the other hand, the inspections performer', at Oyster Creek l
prior to that time were not similarly qualified. The j
1 2
inspection procedure applied in 1983/84 was less conservative than that used in 1986 (higher search speeds' and less search j
s.
unit overlap). Furthermore data presented by GPUN to show
]
conservative interpretation of indications and consistent J
results between the two inspection techniques seem 4
e inconclusive, lacking in statistical significance, and not 1
borne out by the misinterpretation of the indications in Welds'NG-C-23 and NE-1-27. Initially, GPUN claimed credit I
for inspections performed prior to the establish.nent of current guidelines for inspections (i.e., the NDE Coordination _
i plan agreed upon by NRC, EPAI, and BWROG, as upgraded in September 1985) Subsequently, GPUN altered its position-and agreed not to apply credit to those early inspections.
Acceptance of GPUN's new position is recommended since this new position conforms with the guidelines of Generic Letter 88-01 and NUREG 0313, Revision 2.
+N%
2.5 Current Plans for Mitinatina Actions Mitigating actions planned for Refueling Outages Nos. 13 and 14 include partial replacement and stress improvement of numerous inspectable welds (summarized in Table 6), implementation of hydrogen water chemistry, and application of several activities l'
to uninspectable welds as summarized in Table 7.
These measures l
are discussed below in greater detail.
f 2.5.1 Hydronen Water Chemistry The use of hydrogen water chemistry (HWC) will commence
)
15 b
t s.
Table 6' i
Plans for Future Mitigating Actions (a,b)
No. of No. to be Treated I
Unmitigated in Indicated Outane System Welds Action Planned R.O.#13 R.O.#14 l
4 CC)
Recir,.
16 Stress improvement 8
8 CS 21(d)
Stress improvement (C) 3 0.
I fC)
)
SDC 14 Stress improvement 14-0 i
RWCU 46 Partial replacement 4
0 j
10 14 10-1 40(d)
Stress improvement (*)
Partial replacement 4
0 10-2 107 Partial replacement see Note (f) 0 h
CH 8
Partial replacement 8
0 i
Notes:
(a) See Table 3, 4, or 5 for explanation of abbreviations of Systems.
(b) This table excludes 26 uninspectable welds (see Table 7) and 96 welds in the RWCU that are outboard of the second isolation valve (see Section 3 of this report).
(*
(c) SI treatments will be followed by UT inspection.
i (d) Includes 18 welds in CS and 9 welds in IC-1 classified as IGSCC i
Category C/D or C/G.
It is presumed these welds were SI-treated but did not receive post-treatment inspections.
(e) Oniv w,1ds > 12 inch diameter will be inspected following the-appt.o: tion of stress improvement.
c t
j' (f) The number of welds that are shown to be replaced in IC-2 was not actually given in the GPUN Submittals, but it includes all-condensate piping and the portion of the steam piping from the-l-
75' elevation up to the first weld on the 95' elevation.
a j
i s
t i
16 i
~.
~
Table 7 Plans for Uninspectable Welds 1
No, to be Treated No. of in Indicated Outane System Welds Description Action Planned R.O.#13 R.O.f14 Recir.
5 Casting-to-Visual inspection All 5, but date(s) casting welds while pressure not given testing RWCU 5
Dry well Apply corrosion 5
0 penetrations resistant cladding followed by visual inspection while pressure testing IC-1 8
Weld Remove 8
0 penetrations IC-2 2
Saddle welds Replace or clad 2
0 with resistant material 4
Flued head-to-Replace or clad 4
0 F
valve welds with resistant
'A material e
2 Casting-to-Replace or clad 2
0 casting welds with resistant material Explanation of abbreviations Recir. Recirculation System CS Core Spray System RWCU Reactor Water Clean-Up System IC-1 Isolation Condenser System - inside drywell IC-2 Isolation Condenser System - outside drywell 17 l
I r
1 following Refueling Outage No. 12 (January, 19??;,
It is anticipated that this will reduce the suscepttbiltty to IGSOC throughout the Recirculation System, the Reactor Water Cleanup System, the Isolation Condenser up to the second isolation valve, and for 9 of 14 welds in the Shutdown Cooling System.
D 2.5.2 Pipinn Repiscenent' An extensive program for piping replacement is planned at Oyster Creek during Refueling Outage No. 13 as shown in Table 6.
Of particular significance, are the plans for the Isolation Condenser piping outside of the drywells all condensate piping outside the drywell to the containment penetrations and the portion steam piping from 75' elevation up to the 95' elevation is scheduled for replacement with 2
corrosion-resistant materials during Refueling Outage 13.
In addition, four welds in the Reactor Water Cleanup System, four welds in the Isolation Condenser (inside of the drywell),
and all eight of the Closure Head welds are scheduled.for replacement during Refueling Outage No. 13.
2.5.3 Stress Improvement As shown in Table 6, at the completion of Refueling Outage No.14 most inspectable, corrosion-susceptible welds inside of the drywell that have not been replaced or overlayed (except for the Reactor Water Cleanup System) will have been mitigated by stress improvement.
Twenty-two welds in the Core Spray System will be stress improved during Refueling Outage No. 12. A total of 28. welds in the Shutdown Cooling System, the Reactor Water Cleanup System, and in the isolation Condenser (inside of the drywell) will be stress improved during Refueling Outage No. 13. During Refueling Outage No. 14, the final unmitigated welds inside of the drywell l
18 H
1
l s
V in the Isolation Condenser will be stress improved.
j, Ed It should be noted, however, that while GPUN plans extensive a
use of stress improvement treatments, they plan to perform O
post-treatment inspections only on those welds that are greater than 12 inches in diameter. This position, which j
is an alternate to the position outlined in Generic Letter.
88-01 and NURBG 0313, Revision 3, is discussed in Section 3 of this report.
It should also be noted that 20 safe-end welds in the Recirculation System which were considered in GPUN Submittal No. 1 as uninspectable are considered in GPUN Submittal No.
3 as inspectable. As previously discussed, four of those welds were machined, Stress Improved, and inspected during Refueling Outage No. 12. Concerning the remaining 16 welds,-
the following statements are contained in GPUN Submittal No. 3:
... during 12R, both
'C' loop recirculation safe-ends were SI'd and inspected.
The effort required to perform this included machining the OD cladding required to perform this finish and contour adequate for performing UT for IGSCC. Then stress improving follo'wed by a post process UT inspection.
The inspection area included the nozzle to safe-end weld (the safe-end side of that veld, and the nozzle side of that weld for a distance of IT into the nozzle from the weld centerline) and the safe end-to-pipe weld.
These welds contained no a
indications of IGSCC."
"We expect that treating these two safe ends during 12R provided much needed, useful information for stress improving future outages.
Knowledge of the radiological t
19 T
-~-
i i
environment and lessons leaned during the 12R outage will enable us to more efficiently perfom this work i
f in the future. We expect that time and exposure savings j
would be substantial.
Since no indications of IGSOC l
H were found in the 0-loop safe ends in 12R, we consider that these results coupled with the implementation of j
HWC in Cycle 12 provides adequate. assurance that cracks j
will not initiate / grow in the other eight safe ends."
t 1
"... the remaining safe-ends in A, B, D and E loops
]
I
~
of the recirculation system will be stress improved and i
post process inspected in 13R and 14 R.
The four vessel inlet safe ends will be stress improved and inspected
~~
~
during 13R, and the four vesse1 outlet nozzles will be i
stress improved and inspected when the system is y
L chemically decontaminated during 14R. The decon
. techniques will not reduce radiation levels at vessel i
inlet nozzles."
2.5.4 Plans for Uninspectable Welds Plans for tha 26 uninspectable welds at Oyster Creek are i
summarized in Table 7.
Note that by the completion of Refueling Outige No. 14 mitigating treatments will have been applied to all of the uninspectable welds except for five casting-to-casting welds in the Recirculation System.
GPUN's plans for these five welds is to visually inspect them during pressure testing in lieu of ultrasonic testing.
1.
2.5.5 IGSCC Classifications of Welds
.I l
(Following Refueling Outane No. 12)-
Following the inspections and the mitigating actions described above for Refueling Outage No. 12, the classifications of 20 4
l
- .*o l
l the welds in the various systems into the various IGSCC
~
categories are shown in Table 8.
}
GPUN also provided the expected IGSCC classifications of welds following Refueling Outage No. 12, but these are not reproduced in this report because, as discussed later in j
this report, their inspection schedules planned for Refueling Outage No. 12 (which affect those classifications) are j
inadequate and should be changed.
It may be noted by reference to Table 8 that some welds are classified as IGSCC Category C/D and others as IGSCC Category C/G. Explanations of these classifications are not provided, but it is presumed in this report that the welds so classified were those welds that were not given post-SI inspections.
2.5.6 Evaluation of Conformance to Staff Positions and Recommendation The classifications of welds into the various IGSCC categories.
are correctly applied, provided that those welds classified'
~
as IGSCC Category C/D are treated as IGSCC Category D and
-l that those welds classified as IGSCC Category C/G-are treated as IGSCC Category G.
Furthermore, extensive mitigating efforts are planned during Refueling Outages.No. 13 and 14 Acceptance of GPUN's plan for future mitigating actions is, therefore, recommended, except for GPUN's position on post-treatment inspection of welds treated with IHSI (which is discussed in Section 3 of this report) provided that inspections schedules adhere to requirements of Generic Letter 88-01 and NUREG 0313, Revision 2.
21
h i
f a.
l R
I; l
Table 8 Classification of and Inspection Plans for Inspectable Welds (a,b) l l
(Following Refueling Outage No. 12 per GPUN Submittal No. 3)
[j-A. IGSCC Classification of Welds r-i l
Number of Welds of Indicated IGSCC Catenorr 7
System A
3 C
C/D C/G
]
E F
_91 0 Io_1g_1-i Recir.
0 0
T 0
0 0
6 0
84 j
7 CS 0
0 5
10 8
2 0
0 1-26~
t SDC 0
0 0
0 0
9 0
0 5
14 f
2 RWCU 0
0 0
0 0
20 0
0 26 46
~
l 10 0 0
4 5
4 17 0
0 14 44 i
IC-2 0
0 0
0 0
59 22 0
48 129 CH 0
0 0
0 0
2 0
0 J
8 4
d Total 0
0 71 15 12 W F~
n III W j
t i
B. Inspection Recuirements (GPUN interpretation of NUREG 0313. Rev. 2.)
l "l
I Number of Welds of Indicated IGSCC Catenory i
3 System A
B C
C/D C/J D
E 7
C ATo a1 Recir.
0 0
1 0
0 0
3 0
~ff 20 H
CS 0
0 2
10 8
2 0
0 1
23 i
SDC 0
0 0
0 0
9 0
0 5
14 i
RWC'J 0
0 0
0 0
5 0
0 23 28
~
10-1 0
0 2
5 4
7 0
0
-10 28 10-2 0
0 0
0 0
12 6
0 14 32 i
CH 0
0 0
0 0
0 0
0 0
0 Total 0
0 5
15 12 T
9 0
"W W j
C. Number of Welds Scheduled for Inspection Durina R.O. No. 13-
{
Number of Welds of Indicated IGSCC Catenorr System A
B C
C/D C/G D
E F
G Total i
Recir.
0 0
1 0
0 0
3 0
8 12 CS 0
0 0
0 8
0 0
0 1
9 SDC 0
0 0
0 0
9 0
0 5
14 RWCU 0
0 0
0 0
0-0 0
23 23 IC-1 0
0 0
0 0
4 0
0 10 14 10-2 0
0 0
0 0
0 2
0 14 16 l
CH 0
0 0
0 0
0 0
0 0
0 t
~
Total 0
0 1
0 8
13 5
0 61
- 88 (a) These tables exclude 26 welds listed as uninspectable and %
inspectable welds in the RWCU that are outboard of the second isolation valve.
No explanation was provided for IGSCC classifics.tions C/D and C/G.
(b) See Table 3, 4, or 5 for explanation of abbreviations.
~
22 I
- o 2.6 Plans for Puture Inspections a
2.6.1 GPUN's Interpretation of Inspection Reauirements J
The requirements for the at:aber of welds of each IGSCC category at Oyster Creek to be inspected, based on GPUN's interpretation of the NRC Staff position on inspection schedules as delineated in Generic 88-01 and NUREG 0313,
}
Revision 2, is contained in GPUN Submittal No. 3 and summarized in Table 8 of this report. These numbers take into account the following items (1) Previous inspections that have been performed since the inspection programs have utilized currently acceptable methods'and personnel (i.e., in accordance with the NRC/EPRI/BWROG Coordination plan-as modified in September, 1985).
For example, 58 of the 62 IGSCC Category C welds in the Recirculation System were inspected during Refueling Outage No. 12.
(2) The mitigating actions planned for Refueling Outage
~*
No. 13 as g'ven in Table 6.
For example, inspections are not planned for welds that are scheduled for removal or replacement. GPUN expects to implement an extensive piping replacement (especially in the Isolation Condenser outside of the drywell) during Refueling Outage No. 13.'
These welds will become IGSCC Category A welds and will be inspected in the future in accordance with IGSCC Category A inspection requirements.
(3) Allowances for reduced inspection frequency due to implementation of Hydrogen Water Chemistry (HWC).
Specifically, inspection frequency requirements have 23 1
v.<,f ]
+
been reduced by a factor of two for welds of certain'-
1 h
IGSOC categories in the Recirculation System and
[
the RWCU.. GPUN cited experience.by EPRI and.other t
utilities (i.e., Dresden 2 and Peach Bottom 3) co e
i-
.show that substantial reduction of IGSOC crack initiation ~and propagation results when HWC is lj implemented.
Based on this experience, and the
(;
. expected implementation of NWC during the start up 1
f following Refueling Outage No. 12, GPUN's. position 7
[
.is that of a 50% reduction in the number of 3
inspections for selected welds in some of the piping..
l o
3 2.6.2 GPUN's Positions Concernina Inspection Schedules s
The number of welds of each IGSCC category in each piping.
2.-
system at Oyster Creek scheduled-for inspection during:
Refueling Outages No. 13 and No. 14Lis contained GPUN' 1
Submittal.No. 3,-although the identifications of the specific
~
..y welds to be inspected was'not'provided. ~ Summaries of GPUN'ar plans ce shown (in a somewhat modified l format compared with
-the format used in the GPUN-Submittal No.:3):in Table 8 of this report.- Note that this tati;. nows the-inspection plans J
on both a system-by-system basis-as well as a.IGSCC category-by-IGSLC category basis.
A> comparison.of the inspection frequencies planned with inspection frequencies required (as interpreted by GPUN) can readily be made using. Table 8.
Note that such a comperison shows that the proposed j
~
percentage of welds scheduled for inspection during Refueling Outages No. 13 is far less than GPUN's interpretation of Generic-Letter 88-01 requirements. In part, the reduction in inspection frequency proposed by GPUN-is due to a reduction in the inspection frequency of' welds that have been stress improved. The basis of this reduction is discussed-in=Section-3 of this report. Reasons for. reductions-of welds in otiher :
s I
.I 2.
..,___m
c' f_
.x
~
categories were not given, 1
2.6.3 Sarunio Expansion ~
fI GPUN's position on sample expanesion complies with the NRC
- l
- Staff position as detailed in Generic Letter 88-01.with the
~
,j i
IJ following provisions:.
I 1
l (a) Recirculation System Safe-Ends: "If cracking is
-detected in the inlet safe-end-welds in'13R, all L.
eight remaining _ outlet safe-end' welds kill be v
I' inspected ~in 13R."
f k
(b) leolation Condenser Piping Outside Second Isolation' Valver "If indications ~of ICSCC are detected in the initial sample, the additional sample size-wil1Lbe F
approximately equal to that of the initial sample I.'
of the category of weld in which IGSCC was detected, L
but limited to the Isolation Condenser System outside l
{
the second isolation valve.
If IGSCC is' detected l-i in the second semple, all weldslin that~ category will be inapected within the-Isolation Condenser
{
System out. side the second isolation valve."
i ii (c) RWCU Piping:
"Because the RWCU system is the only. system (excluding I
the Isolation Condenser System outside.the second
. isolation valve) which will not be stress improved, i
[-
it will be treated for nample expansions separately.
i Sample expansions will be limited to those welds
~
inside the second CIV.'?
I "Further, the RWCU outbcard of the second containment isolation valve was deferred from the 12 R' inspection j
. n 25 t
3 I
==
w-ew
.e,e aw4-
- = -, w t' s -
er i ea er+-
, J.,, -
~
plan, and sample expanaton pending the development:
'i of.a; separate inspection plan no later than six months 1
from the 12R restart."
i (d)RemaininnWelds(Recirculatiod.CoreSorar. Shutdown Coolinn.-Isolation Condenser Inside Drrwell. and-1
- L Closure Head Pipinat-
"We will meet the sample. expansion requirements of-
]
GL 88-01. That is,'for each category of weld, we
~
.will inspect an' equal number of welds in the second sample and, if. cracking is detected in'the second-sample, all remaining welds in the applicable' category.
will be-inspected."
2.6.4 Evaluation of GPUN's Positions and' Inspection Schedules-Pertaintag to GPUN's position concerning'of Generic Letter 88-01 requirements for inspection schedules: some portions of their position are acceptable and some are unacceptable
^
as stated below:
1 GPUN's position on inspection of welds that are scheduled
'for replacement is acceptable, so acceptance of this portion of GPUN's position is recommended.
- 1 GPUN's position on taking credit for inspections performed i
during Refueling Outage No. 11 and Refueling Outage No.
12 (but not for-Refueling Outage No. 10) is acceptab1'e, so acceptance of t.his portion of GPUN's position is recommended.
- i GFUN may be justified in taking a 50% reduction in-j inspection frequency on certain welds after (but not beftre) it has been established thnt the implementation-25 I
l u
n.
j of HWC has produced > water chemistry that is effective r.
in mitigating IGSCC. Clearly, this was not established Il 1
H i".
at the time of preparation of GPUN Submittal'No. 3 since
\\
\\
that document was prepared at about the same time that i
p-b implementation of HWC was scheduled.,Thus, GPUN's.
L-proposed reduction in inspection frequency based on anticipated implementation of HWC should be rejected..
GPUN'should re-submit their request after they establish-
- )
(to the satisfaction of the NRC Staff) that implementation.
[
of HWC has produced water chemistry that is effective
.j in mitigating IGSCC.
j
- )
h Pertaining to GPUN's position concerning reduction of inspection frequency to. lower levels than requirements of 1
l 2
Generic Letter.88-01-(as interpreted by GPUN and discussed
!L above):
e f,
As discussed in Section-3 of this= report, rejection of, GPUN's proposal to limit the number of post-treatment j
inspections of stress improved' welds is recommended.
Thus, it is further recommended that'the corresponding.
j reductions built into GPUN's proposed future inspection
.d schedule should also be rejected.' Welds that are classified as IGSCC Category C that-have not.been previously inspected should-be reclassified as IGSCC Category G and inspected during'the next: outage-(Refueling 1
Outage No. 13). Similarly, welds that are classified l
as IGSCC Category C/D should-be treated as IGSCC Category
-s D, and inspections should be planned in accordance with.
]
[
Generic Letter 88-01 for IGSCC Category D welds.
U The reductions in the frequency of inspections of welds.
classified as IGSCC Categories C, D, E,-and G are not j
justified. The inspection schedules for these welds 27 s
S
= -
, : ; y should be revised in:accordance with Generic Letter 88-01
~
for those categories, a
.p It is especially further recommended that all IGSCC Category G welds ~should be inspected during the next refueling outage (Refueling Outage No. 13) as required
.i 1
1 by Generic Letter 88-01.-:
l 1
Pertaining to GPUN's position concerning the five casting-to-casting welds in the Recirculation System: 'GPUN is not justified in considering these welds as uninspectable.--
Techniques to inspect casting'or welds metal (such'as using.
L refractive waves) are available in~the industry. Thus, rejection of GPUN's position on these welds is recommended, r
and GPUN should inspect-these welds by Refueling Outage No -
_j
- 14. Other aspects of GPUN's'plaer pertaining to uninspectable welds are accepte' ? ;.. and their; acceptance-is recommended.
I u
GPUN's position.on sample expansion is-unacceptable. Sample-expansion should be based on the-IGSCC categories-rather a
than based on system. That is if crack (s) are found in welds:
j of a given IGSCC category, an additional sample of-approximately the same size should be inspected. Thus,.
i rejection of GPUN's position on sample expansion is recommended, and it is further recommended that-GPUN.should
. amend their position to comply with guidelines. presented in Generic Letter 88-01.
i 2.7 Changes in the Technical Specification Concernina ISI GPUN proposed an alternate position to the NRC Staff position
~
concerning a change to the Technical Specification. This alternate-28
'l
.i s
+
4 position is discussed in Section 3 of this' report.
I 2.8 Confirmation of Leak Detection-in the Technical Specification.
(-
.i L.
2.8.1 Conformance with Position C of Renulatory Guide 1.45 GPUN Submittal No. I contained the following staterents.:.
" Leakage detection systems for 0yster Creek.were reviewed
-i by the NRC Staff during'the Systematic Evaluation Program.
I
~
and the results were documented-in Section 4.16.2 of Integratei Plant Safety Assessment Report for'0yster Creek, s
I NUREG-0822 dated-January, 1983. The actions identified in that report have been completed with the exception of.
the airborne particulate and gaseous radiation monitoring system (APGRMS). GPUN's recent submittal of July 1, 1988--
j states that installation.of a new APGRMS will be completed 3
during the operating cycle 12. The submittal also jl identifies that there are several leak detection methods available for unidentified leakage:into the-containment sump at Oyster Creek which operate on diverse principals."
"The normal method of monitoring unidentified leak rate is to obtain flow integrator readings from. containments sump pump discharge every four hour period and calculate average flow rate. Approximately 1 gpm can be measured in a four hour interval. This-methodology is identified-g in Oyster Creek Technical Specifications as the primary method of leakage measurement."
j "When the flow integrator is not available, the average leakage rate can be calculated using the known volume I
29
',{ j
.i between the high and'the low.-level alarms for the sump l,
s and the time required to f111'the sump'between thesel j
levels."
P*
"A recorder available in the control room also provides.3
~
continuous indication of an estimated unidentified leak' 1
rate to the containment sump by utilizing a differential presacre:si nni as'a result ofithe_ sump level change. The-8 asnsitivity cf the recorder is approximately 0.2 gps."
~
f
" Additionally, a timer available in the!480 volt' switch l
~
I gear room'provides the run time of-the-containment sump:
pumps. This run time.along with the estinsted. flow rate 3
of the sump pumps can provide-approximate-leuk rates.~ This.
methodology is utilized every four hours'during power operation."
"Also, an' annunciator will alarm in the control room lif-the time to fill'the containment-sump-is:too short an-
-interval. The time associated with-this alarm is set to
(
bring in the alarm if unidentified leak rate equals or-exceeds 4 gpm."
1 "These methods provide quantitative' indications of.
unidentified RCS leakage inside containment and also provide -
assurance that. unidentified leakage can be detected;and quantified during Cycle 12 operation pending_ operability-of the new APGRMS".
7 L
2.8.2 Other Leak Detection Requirements 1
g Generic Letter 88-01' states the following-P
~
" Plant shutdown should be initiated for inspection
'r l
-l I
30
(
L 7-
- _ ____ _ _ _ =._ _ _ _.
. r
6 j
, 3..,
t and corrective. action when, within any: period of; j
I.,
'24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or less, any' leakage detection system j~
indicates an increase in rate of unidentified leakage in excess of.2 spa.or its equivalent, or when the it total unidentified leakage attaina a rate of 5 spe_
.t or equivalent, whichever occurs first.- For sump, j
f
. level monitoring eystems wit fixed-measurement-interval methods, the level-should bel monitored at l
l 1
approximately.4-hour intervals or less."
v.
2.
" Unidentified leakage should' include all leakage
- a other than
- (s) leakage into closed systems, such l
as' pump seal or valve packing-leaks that are captured.,
flow metered,'and conducted to a sump =or collection-tank, or (b) leakage into the containment atmosphere:
fron sources that are both.specifically" located-and I.
known either not to interfere with the. operations of unidentified leakage. monitoring ^ systems or.not:
to be from a-throughwall crack in the piping within l
the reactor coolant pressure boundary.
~
[
i 3.
"For plants operating with any.IGSCC Category D,_
E, F, or G welds, at'least one'of the leakage h
measurement instruments associated with each sump:-
l shall be operable, and the outage time for inoperable instruments shal1~be limited to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or q
immediately initiate an orderly shutdown" E
l' In addressing these requirements the GPUN Submittal No. l'
[
stated the following:
4 j
"By amendment 97 to Provisional Operating License No.
f DPR-16 for Oyster Creek, the limiting conditions for h
operation and surveillance requirements were authorized L
31 l
1 m
...u..
,f_..._
' t c:7.: ;*J for the Reactor Coolant System leakage.
This amendment _
added,two new definitions'(identified ~and unidentified D:
leakage) to_ TS Section:1.0:1 revised TS 3.3.D'to include ~
LCO's for the containment sump flow monitoring system.
L and the equipment drain tank <nonitoring_systemt and-added" l;
-a new surveillance section-TS 4.3 H.
This amendment
~
7 incorporated GPUN's response dated September 8,_1983, a
to IE Bulletin 82-03."
c.
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-1 4
"On March 17, 1987 GPUN submitted Technical _ Specification-Change Request-#158 which-adds additional conservatism i
to these_ requirements by proposing to limit the unidentified leakage for the Reactor Coolant System to' j
1 a maximum leak rate increase of 2 gpa within.any 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> q
3 period while operating at steady state power.
As of:
Q this date, the NRC: Staff has'not completed their review of.this proposed change. -If. approved, the TS:would also address item 1 of the NRC Staff _ position."
The section on surveillance in the-Techadcal Specification.
l l
(Section 4.3.H) states:
Et "1. Unidentified leakage rate shall be calculated at-
]
1 east once every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />."
"2. Total leakage rate (identified and unidentified)1 shall be calculated at least once every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />."
I G=O "3. A channel calibration of the primary containment sump flow integrator and the primary containment' equipment drain tank flow integrator shall be conducted at least once per 18 months."
A i
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2.6.3 Evaluation'and Recommendation-1 GPUN's position on leakage. complies with the NRC Staff position so acceptance of tha?.r position is recommended.
2.9 Plans for Notification of the NRC of Flaws L
z4 2.9.1 GPUN's Position t?
m GPUN plans to notify the NRC of~any flaws-identified that Y
do not meet I E 3500 criteria of Section XI of the Code for.
l' l
continued: operation without evaluation, or a' change found in the condition of the welda previously known to be cracked, o
and our evaluation of the' flaws for continued operation and/or 7
U' repair plans. However, GPUN' stated that the-NRC review shall not be a constraint for restart of the plant.
t:
b.
2.9.2 Evaluation and Recommendation-a.
u GPUN's position 'is not in'coc:pliance with the NRC Staff q
position as delineated in Generic-Letter 88-01. The NRC D-should approve the' methodology and procedure before restart
(
of the plant. Thus, rejection of GPUN's position is q
J.
recommended. GPUN-shonid revise its position to comply with the guidelines provided in' Generic Letter 88-01 and NUREG j
0313 Revision 2.
4
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'3.
ALTERNATIVE POSITIONS-1 i
3.1 GPUN's Alternate Position Concernina Welds in the RWCU f
i 3.1.1 GPUN's' Position j
GPUN, according=to.GPUN Submittal'No. 1, considered the
?
Reactor' Water Cleanup (RWCU) piping outboard of:the outermost r
Containment Isolation-Valves >to be outside-of the scope of j
NRCBG'0313, Revision:2 and therefore, inspections will not f
be performed =on these welds; Reasons given by GPUN are-that t
a pipe rupture'in that portion of the RWCU..would not cause a safety hazard and inspection of that portion of the RWCU-would cauce" excessive exposure to inspection personnel-
'~
~since it is a high radiation: area. 'In support of these.
claim.a. GPUN Submittal No. 1 contained the following statements:-
"A pipe failure outboard of the outermost Containment.
r I
Isolation' Valves-(CIV).;would not have nuclect safety
?
^
ccasequences. The effects-of postulated pipe' failures outside containment on equipment and structures.necessary to shut down the reactor were-evaluated-as described in Section 3.6.2.6 of the-FSAR.
A double-ended rupture of the RWCU piping outside the. outermost isolation CIVs l
4 would result in a low reactor coolant level.and automatic isolation of the RWCU from the reactor..For this reason,.
there would be no. compromise in the ability to safely shut down the reactor. The radiological releases for-e such a break would. be within the secondary containment-boundary and would not cause 10CFR20.11mits to be J
exceeded."
l' "This piping is also-a high radiation area.
While decon 34 y
2:
-a,
,..~.,,,.n.,n..,
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r c.,_
.x will reduce exposure,:there would still be a-lot of dose
~
]
expended-in prepping the: welds, inspection, scaffolding, J
etc. The man-ren exposure for performing inspections-and weld crown reduction (excluding' scaffolding) is l
.,j estimated at 343 man-ree w/o decon and-69 man-res w/decon.
Scaffolding and insulation removal and reinstalling is.
estimated'at 200 man-rem w/o decon'and 40 man-rem-w/decon."
4 GPUN Submittal No. 2 adds-the following additional.information pertaining to their position on inspection of RWCU welds:
w 9
"We have determined from a-review of theLpiping-stress j
reports, piping fabrication and installation records:
(a) The operational piping stresses are predominantly
{
higher,approximatelybyafack:orof2,inboardofthe?
second isolation valve.
%erefore, welds residing inboard
~
have a higher propensity'for IGSCC than-those outboard.
. (b) There is'no documentation that of the second valve.
weld repairs exist within'the welds outboard of the~second 2
valve which could increase the IGSCC sensitivity over those welds residing inboard of the second-valve.
(c) a j
Also, there is no evidence of-signtf Nant~ piping material chemistry differences bet %een t.
>ti.ing inboard and L
$d)'
outboard of the second isolation v. Ave. Therefore, the propensity for IGSCC in regard to alloy composition is relatively the same."
,q t
"GPUN previously estimated man-rem exposures... for
)
insulation re3 oval, weld crown reduction and inspections of the Category 'G' RWCU wilds. Since GPUN'is-now s
planning chemical. decontamination for 13R, we can' expect a major reduction in the exposures.
For example, the l
original dose estimate-(345 man-rem) without 1
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r e
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,,; y If these welds wereLfabricated-to the same criteria as the outboard welas, ti,sa GPUN'coald classify these welds' 9-7 J
as representative of: the IGS00. susceptible welis. outboard a
of the second valve.
UT-of these welds between the p
I.
valves, with an additional 10 welds. outboard of the second-o a
valve, would provide a representative sample for the.
d' 13R IGSCC inspections."
-J i
"In response to the staff request, GPUN has reviewed' q
the piping specification for the.RWCU' system,=and has-determined that all welds requires 100% radiography..
Further, the piping and welds inboard of~the first 1 solation valve were' fabricated-to ASME Section I, 1965 edition, and the' piping and welds beyond:the first valve were fabricated to ASA B31.1, 1955 edition."'
2"
" Based on these facts,'our' original proposal...'has-merit. The RWCU welds within the'IGSCC boundary are.
2 differentiated by-their operational stresses. For.
exampic, those welds residing inboard of_the:second valve j
have a higher propensity'for IGSCC'than those outboard ~
of the second valve, because'the operational stresses-are higher by a factor of'two."
a "However, in responoe to the Staff's generic concern for RWCU welds outside of-the second_ valve, GPUN has opted to include 10 (approximately 10%) of the welds outboard of the second valve in the initial 13R UT inspection sample.. If indications are characterized as IGSCC in-this inspection sample,-GPUN will: approach-the staff on their disposition and any plane for sample expansion."
a "If no indications of IGSCC are found outside of the-e
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i.
decontamination could be reduced to approximately 70 man-rem. However, these estimates to perform inspections on the 96 RWCU welds outside the'second valve are still
]
significant, and do not include the dose from' scaffolding J
work."
i n
j "Therefore, we believe it is prudent to implement _an!
]
inspection program which includes's visual check for'-
l cracks in welds outboard of the second isolation valve and to ultrasonically examine these welds only.in the.
E event of cracking being detected in the more susceptible welds inboard of the'aecond valve."
j 1
"Further, the results of our p'evious augmentied
- l examinations conducted during the-11R and 12R outages show no evidence of-IGSCC inboard of the second' valve.
It is-also noted, that for those welds' examined, their.
j operational stresses are in excess of two times that-e of the welds residing outboard of the second: valve, specifica117thosehigh'stressveldsatthereEirculation:-
{
a 2
piping connection points. Therefore,rahould flaws be-detected within the welds inboard of the second. valve 1
during examination of the 1nitial inboard' sample, a
(
maximum of 10 percent of.the welds outboard of the second valve that reside within the IGSCC boundary (operating
,l temperature > 200*F; and pipe size > 4 inches) will be-1 t
examined."
GPUN's position was subsequently altered as indicated:in the following' statements from GPUN Submittal No. 4:
"... The Staff requested that GPUN review the fabric,ation records to determine whether the welds between the first and second valves were radiographed during construction'.
r.
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second isolation valve'_during 13R,-there would be-additional technh al-justification for our' original plan He would thm reinstate this inspection plan ~after-
~i the 13R outage. Therefore for post 13R required RWCU d
wolf hopections, a visual check would be performed during:
the Hydro test cf the welds outboard of the second d
isolation valve. UT examinations would be performed for those welds only-in the' event of IGSCC1 being detect.ed
_.i in the more susceptible' welds inboard of the'second valve.-
For IGSCC detected within-the welds' inboard ~of the~second
}
isolation valve during; examination of tne initial inboard:
sample, a maximuniof.10' percent of the welds outboard of the second valve that reside within the IGSCC boundary l
2 would be examined."
3.1.2 Evaluation and Recommendation i
The NRC Staff, in the development of their position-(i.e.,
that Generic Letter 88--01 applies to all BWR piping made-of austenitic stainless: steel that is four inches or larger.
1
-in nominal diameter and contains reactor coolant at a temperature above 200*F during power operation regardless of Code classification), recognized that high' radiation exposure to inspectors would result; however,_despite this i
consideration, they imposed the requirement in Generic Letter-88-01 that the same inspection' requirements should. apply.
outboard of the isolation valve as those that apply inboard of the isolation valve.: Since the time Generic Letter 88-01 i
j was issued, the NRC Staff relaxed its position.to permit:
i o
i a sampling plan to apply to the portion of. the RWCU that' j
is outboard of the second isolation valve. GPUN's plan for J
UT inspection of approximately 10% of the, welds during 1
Refueling Outage 13 1s acceptable 1and~in accordance with the sampling plan permitted by the NRC Staff. Thus,
. I J
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4
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acceptance'of that portion of-GPUN's position is recommended.
However, GPUN's plans for~ inspections during subsequent refueling outages is not in accordance with the NRC Staff's
^
modified position'so rejection of that portion of GPUN's-O plan is. recommended. GPUN should revise their long range plans (1'.e., plans for inspections during Refueling ~ Outage 7,
l, 14 and beyond) to inspect a sample of about 10% of the welds; during each outage.
3.2 GPUN's Alternate Position Concerning ISI in the Technical Specification 3.2.1 GPUN's Position GPUN's position is not to modify the.Techn'ical Specification q
to specifically delineare conformance'concerning inservice.
inspection (ISI) because of the following reasons.:
1 I
GPUN stated that changes to the Technical Specification shoul'd be viewed in light of=the NRC. Proposed' Policy.
]
Statement on TS Improvements for Nuclear Power' Reactors-j (52FR3788, 2/6/87), the intent of which is to improve
~
nuclear safety through the development of more tperator-4 oriented TS, improvement of TS" Bases, reductior of action
- l' statement induced plant transients and more' efficient use of NRC and industry resources.
GPUN, believes that j
~
a change to the TS concerning ISI would not support the Proposed Policy. Thus, in lieu.of_a TS change, GPUN-proposes the inclusion of their statement of support
[
of the NRC Staff position ~on ISI in their Inservice Inspection Program pending the final recommendation of-i the Technical Specifications Improvement program.
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3.2.2 Evsluation and Recommendation
!i The reasons given by GPUN for not changing their Technical Specification have already been' considered and discounted by the NRC Staff in the development of their position.as
' delineated in Generic Letter 88-01.' Furthermore, a statement-a
,3 in the alternative documents would not be as' enforceable as a statement in the TS. 'Iherefore, rejection of the GPUN -
. position is recommended.
It is'further recoro nded that.
GPUN should amend the TS on.ISI in accordance with Generic Letter 88-01 to include a statement that the.ISI program-will comply with the'NRC Staff position on inspection scheduled, methods and personnel, and sample expansion.
t
< fs 3.3 GPUN's Alternate Position Concerninn-Inspections of Stress-Improved Welds 1
3.3.1 NRC Staff Position e
N Section 5.3.1.3 ofsNUREG 0313 Revision 2 states that an
. ultrasonic examination should be applied after SI treatment s
as part of the process.
Section 5.3.1.7.of NUREG 0313,LRevision'2' states that' stress improved welds.are considered to be Category G wieldsents until the post-SI inspection has been performed.
~
Section 5.3.2.1 of NUREG 0313. Revision 2. states that.all l
IGSCC Category C welds should be inspected within two refueling cycles after the post-SI inspection, and every 10 years thereafter.-
40 l
j l
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m y + >,s.
c m.
~e 3.3.2 GPUN's Position i;
GPUN stated they consider that, for certain sizes of piping.
performing stress-improvement (SI).without 100%.immediate1 post-SI inspections is n' prudent technical approach to mitigating IGSOC and that performing a 100% inspection over the following two outages is not warranted. GPUN 4
- presented a technical analysis to support this claim._ The conclusion of that analysis ist if a_ crack _will not grow
-d to an unacceptable depth within an operating cycle in the as-welded condition, the same crack would.not grow to an j
unacceptable deptli within an operuting cycle if stress improved.
i In consequence of those technical analyses, GPUN considers it prudent, in view of ALARA considerations, to reduce the number of inspections of SI welds and to eliminate th r post-
[
treatment inspectiont.of small diameter welda chat are.givun 4
SI treatments. GPUN also believes that it is prudent to.
I perform SI on small diameter welds, even if that treatment L
is not followed by inspection because the SI treatment will 1
provide an added measure of safety.-
3.3.3 Evaluation and Recommendations i
)L The NRC and GPUN positions are obviously in conflict. The 5
results of extensive research= programs have been incorporated into the development of-the NRC Staff positions. Although, the GPUN position that it is prudent to perform SI
. small diameter welds even though post-weld inspections are not.
j performed is correct, these welds.should be considered as IGSOC Category G welds, in conformance with the NRC position.
j Additionally, rejection of the GPUN position on reducing c,
the inspection frequency of SI treated welds is recommended..
41
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7,
- 4. CONCLUSIONS AND RECOPMENDATIONS GPUN has indicated that they endorse'and accept.several of the thirteen NRC Staff positions outlined in Generic Letter 88-01. In particular,
~
[_
they endorse those pertaining to materials, processes, water chemistry, weld = overlay, partial replacement, and crack evaluation and repair criteria. They indicated that they also accept, with certain provisions (some acceptable and..some unacceptable)~, the NRC Staff positions pertaining to inspection method and personnel, inspection schedule,-
sample expansion, leak detection, and reporting requirements.
a GPUN has applied extensive mitigating treatments in the form of.' improved water chemistry, partial replacement, weld overlays, and stress improvements treatments..GPUN plans additional mitigating efforts during the next two refueling outages.
Following these improvements,
~
all welds-(except for five welds between castings) inside of the drywell-(except for the RWCU) will have been replaced, overlayed, or stress improved. Plans for the five casting-to-casting welds is to visually-inspected them during pressure testing.
GPUN classified several welds as IGSCC Category C/D and several other
[
welds as IGSCC Category C/G. No explanation of these classifications were provided, but it is presumed in this report that'these are welds 1 that were Stress Improved (SI) but not'given post-SI inspections.
This is acceptable, provided that they are treated as IGSCC Categories D and G for inspection purposes. GPUN's classifications of other welds is acceptable.
4 GPUN has adopted inspection methods and personnel that comply with the NRC Staff position (1.e., in accordance with the NRC/EPRI/BWROG Coordination Plan as upgraded in September,'1985), and performed inspections during Refueling Outages No. 11 and No. 12.
An inspection program was presented for Refueling Outages No. 13 and No 14; however, the number of welds to be inspected is not in compliance with the NRC 42 M
dO
~
Staff position. GPUN has appiled re' ductions to the number of welds to be inspected because of: (1) anticipated implementation of HWC, t
(2) a position to decrease the number of inspections of stress improved
(
h welds, and (3) other unspecified reasons.-
[
i GPUN initially interpreted the scope of NUREG 0313 Revision 2 to exclude the welds in the RWCU that are outboard of the second isolation.
valve.
In support of this action, GPUN presented reasons thatt (1)
L 7
this action would save considerable iadiation exposure to inspection i
personnel and that it would cause no safety hazard, (2) stresses in the portien of the-RWCU inboard of the second isolation valve are higheri (so these welds are more'likely to develop IGSCC), and (3) if IGSCC is found in welds in the portion of the RWCU that is inboard of.the i_
second isolation valve, inspections of the remaining portion of the RWCU would be undertaken. These reasons have, no doubt, been considered
(
and discounted by the.NRC Staff in the development of their. positions.
GPUN subsequently revised its position-on inspection of welds in the y
portion of the RWCU that is outboatd of the second isolation' valve, and they presented a plan:to inspect'approximately 10% of those welds ~
q l
during Refueling Outage No. 13.
This is acceptable, but: they stated l
t that if no cracks are found that their position would revert to that originally stated during subsequent outages..Their position for Refueling Outage No. 14 is not acceptable.
GPUN declined to amend the Technical Specification on ISI to include a statement that the inservice inspection program for piping'will be' in conformance with the NRC Staff positions on schedule, methods and personnel. Rather they proposed an alternative position that such a statement would be incorporated into the Inservice Inspection Program.-
l l
Such an alternative would not be as enforceable as a statener.t in the Technical Specification.
g Leakage detection proposals presented by GPUN include provisions to J
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l insure compliance with Position C of Regulatcry Guide 1.45. They have:
i
~
'I previously proposed changes in the TS to ensure additional conservatism to leakage requirements, and requested delay of-further changes pending.
~
the outcome of NRC review of that request.
As a result of this techi.ical evaluation, the following recourandations j
are made.
-J (1) Acceptance of GPUN's classifications of welds provided that' welds classified as IGSCC Cate8ory C/D and IGSCC Category C/G?
q are treated' as IGSCC Category D'and IGSCC Category G, respectively, for inspection purposes.
u 1
(2) Acceptance of GPUN's' plan for Refueling Outage No. 13 for UT inspection of 10% welds in that portion of the RWCU that is outboard of the isolation valves. However, rejection of GPUN's j
plans for Refueling Outage No. 14 is recommended. GPUN should revise its long range plans to include ITT inspection during
.i Refueling Outage No. 14 (and subsequent' outages) to utilize a sampling plan similar to that p1'anned for' Refueling Outage.
No. 13.
g l'
(3) Rejection of GPUN's position to reduce the number-of:due to-implementation of hydrogen water chemistry (HWC). GPUN should resubmit their proposal after they can demonstrate'(to the-satisfaction of the NRC Staff) the effectiveness of HWC to-mitigate IGSCC at Oyster Creek.
l' l
[
(4) Rejection of GPUN's position to reduce inspections on SI-treated f
welds. GPUN abould revise its inspection plan to adhere to ~
(,
the NRC Staff position on inspection schedules of SI-treated O
welds as delineate'd in Generic Letter 88-01.
')
(5) Rejection of CPUN's proposal to reduce inspection frequency E
l' h
44
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~
of welds classified as IGSOC Categories C, D,;E,-and~G and
~'
IGSCC Categories _C/D and C/G... GPUN should revise'.'its inspection schedules for these.in accordance with Generic Letter 88-01'
+
as discussed in Section 2.6 of this report.
Of particular concern: all IGSCC Category G welds should be inspected during Refueling-Outage No..-13.
J (6) Rejection of-GPUN.s position that. five casting-to-casting. welds-in the Recirculation System are uninspectable welds.- GPUN should apply techniques available in the industry as discussed in Section 2.6 of this report and inspect those welds no later than Refueling' Outage No. 14.
(7) Rejection of GPUN's position on sample expansion. GPUN should revise its position so'that sample expansion is based on guidelines provided in Generic Letter 88-01, i.e., when cracked-welds are found, a new sample of welds (approximately the same_
size as the. original sample) should be selected from welds'-
l of the same IGSCC category.
l q
a
.(8) Rejection of GPUN's position to include changes pertaining I
to ISI in the Inservice Inspection Program rather than to. modify-the Technical Specification on ISI.
u y
(9) Rejection of GPUN's position on flaw evaluation. GPUN should-revised its position as discussed in Section 2.9 of'this report.
i (10) Acceptance of the remaining portions of the GPUN Submittals.
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- 5. REFERENCES
[i 1.
" Technical report on Material' Selection and Processing Guidelines ly for BWR Coolant Preseure Boundary Piping," NUREG 0313 Revision 1
2,.U.S. Nuclear Regulato'ty Commission, Office of Nuclear Reactor y-Regulation, January, 1988.
2.
" Investigation and Evaluation of Stress 4 orrosion Cracking in-Piping'
- j
)
of Light Water Reactor Plants," NUREG 0531, U. S. Nuclear Regulatory _
J
.\\
-Commission, February. 1979.
.q i
0 3
"NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping,".
'1 1
Generic Letter 88-01, U.S. Nuclear Regulatory Commission, January
]
25, 1988.
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