ML19332C940
| ML19332C940 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 11/16/1989 |
| From: | Devine J GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 5000-89-1838, NUDOCS 8911290205 | |
| Download: ML19332C940 (3) | |
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GPU Nuclear Corporation hggs One Upper Pond Road r.
WwWu Parsippany, New Jersey 07054 201 316-7000 TELEX 136-482 ~
'Vrlter's Direct Dial Number:
November 16, d89 5000-89-1838 U.S. Nuclear Regulatory Commission Attentions-Document Control Desk Mail Station Pl-137 j
Washington, D. C.
20555 i:.
Gentlemen Subjects Oyster Creek Nuclear Generating Station (OCNGS)
Docket No. 50-219 IGSCC Inspection Plan - RWCU
References:
(1) NRC Ltr., dated 2/16/89 (2) GPUN Ltr. 5000-88-1605, dated 8/1/88 On November 30,-1988, GPUN, NRR and Region I representatives discussed the
-inspection criteria for the Reactor Water Cleanup System (RWCU) outboard of the second containment l' sole. tion valve.
In light of the high man-rem exposure for the inspections, and the capability to isolate this portion of the system from the Reactor Pressure vessel by the containment isolation-valves, the GPUN and NRC personnel agreed to address the 13R inspection criteria for this portion of the'RWCU in a-separate transmittal six months after the restart from 12R.
In response'to the staff request, GPUN has reviewed the RWCU system welds, and I
has prepared.an inspection plan for 13R. 'This inspection plan has taken into L
account the parameters affecting the IGSCC susceptibility of the RWCU system l
-(i.e. stress levels, piping material chemistry and weld repairs) as well as the l
additional man-rem exposure to perform the Category "G"
incpections.
We have-determined from a review of the piping stress reports, piping fabrication and installation records: (a) The operational piping stresses are predominately higher, approximately by a factor of 2, inboard of the second isolation valve. Therefore, welds residing inboard have a higher propensity for IGSCC than-those outboard of the second valve.
(b) There is no documentation that weld repairs exist within the welds outboard of the second
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valve which could increase the IGSCC sensitivity over those welds residing inboard of the second valve. (c) Also, there is no evidence of significant
-piping material chemistry differences between the piping inboard and outboard j'
of'the second isolation valve. Therefore., the propensity for IGSCC in regard to alloy' composition is relatively the same.
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C32035289 GPU Nuclear Corporation is a subsidiary of General Pubhc Utihties Corporation I
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U.S. NuclOtr Regulttrry Commircicn Page 2
- ' GPUN previously estimated man-rem exposures (Ref. 2,. Item 4c) for insulation
' removal, weld crown reduction and inspections of the Category "G" RWCU welds.
Since GPUN is now planning chemical decontamination for 13R, we can expect a L
major reduction in the exposures.
For example, the original dose estimate (345 i
man-rem),without 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 work.
Therefore, we believe it is prudent to implement an inspection program which includes a visual check for cracks in welds outboard of the second isolation valve and to ultrasonically examine these welds only in the event of cracking being detected in the more susceptible welds inboard of the second valve.
L' Further, the results of our previous augmented examinations conducted during the llR and 12R outages show no evidence of IGSCC inboard of the second valve.
It is also noted, that for those welds examined, their operational stresses are in excess of two times that of the welds residing outboard of the second valve, specifically those high stress welds at the recirculation piping connection.
points. Therefore, should flaws be detected within the welds inboard of the
.second valve during examination of the initial inboard sample, a maximum of 10 percent of the welds outboard of the second valve that reside within the IGSCC boundary (operating temperature >200*F; and pipe size 2 4 inches) will be examined.
t In order to preserve the OCNGS IGSCC. inspection plan within one source document, GPUN will submit a revision to our previous GL88-01 response.
This document will include this inspection plan for the RWCU system and outline the revised piping replacement plans for the 13R outage.
If you have any questions, please contact Mr. Michael Laggart, Manager, BWR Licensing, at (201)'
316-7986.
Very truly yours, l'
J.
C. DeVine, Jr.
Director Technical Functions DKC/DJ/cjg Attachment C32035289
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ce: Mr. William T. Russell,.Adminictrator'
-Region'I-LU.S. Nuclear Regulatory Commission N'! '
475 Allendale Road King of Prussia,-PA
- 19406 NRC Resident Inspe= tor Oyster, Creek Nuclear Generating Station Forked River, N.J.
08731 Mr. Alex Dromerick.
U.S. Nuclear Regulatory Commission jc
-Mail. Station Pl-137 f,
. Washington, D.C.
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