ML20216H854
ML20216H854 | |
Person / Time | |
---|---|
Site: | San Onofre ![]() |
Issue date: | 09/29/1999 |
From: | Scherer A SOUTHERN CALIFORNIA EDISON CO. |
To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
References | |
NUDOCS 9910040074 | |
Download: ML20216H854 (8) | |
Text
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%[M souinrRN CAttf 0RNIA A. Edward Scherer EDISON
- =bm an wason isumiione compan, September 29, 1999 U.S. Nuclear Regulatory Commission Attention: Document Control Desk
~ Washington, D.C. 20555
Subject:
Docket Nos. 50-361 and 50-362 Mechanical Nozzle Seal Assembly Code Replacement Request for Relief from 10 CFR 50.55a San Onofre Nuclear Generating Station, Units 2 and 3
References:
See Enclosure 1 Gentlemen:
By this letter, in accordance with 10 CFR 50.55a(g)(5)(iii), Southern California Edison (SCE) submits the enclosed request for relief from ASME Code, Section lli requireraents in 10 CFR 50.55(a)(3) to use the Mechanical Nozzle Seal Assembly (MNSA) as an Alternate ASME Code Replacement at the San Onofre Nuclear Generating Stationi Units 2 and 3 for the period of operation beginning with the Cycle 11 refueling outages and ending with the Cycle 12 refueling outages.
BACKGROUND San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 began their second ten-year interval on April 1,1994, under the 1989 Edition of the ASME Code,Section XI, with no Addenda. By letter dated January 29,1999 (Reference 1), the NRC granted interim approval for use of the MNSAs at SONGS for the period of operation ending with the Cycle 11 refueling outages, in response to SCE's request (Reference 2).
During the Cycle 10 refueling outages SCE inspected the MNSAs which were installed during the Cycle 9 mid-cycle outages. The results of the inspections were satisfactory, and a summary of the visual examination results was included in references 3 and 4, when SCE submitted the required post outage NIS-1 forms. These satisfactory inspection results support the continued use of the MNSAs at SONGS.
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9910040074 990929 PDR ADOCK 05000361 P
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P. O. Box 128 San Clememe. CA 92674 0128
' 949-368-7501 -
Fax 949-368-7575 L
a Document Control Desk.
If you have any questions or would like additional information regarding this issue, please contact me or Mr. Jack L. Rainsberry at (949)368-7420.
Sincerely, Enclosures cc:
E. W. Merschoff, Regional Administrator, NRC Region IV J. A. Sloan, NRC Senior Resident inspector, San Onofre Units 2 & 3 L. Raghavan NRC Project Manager, San Onofre Units 2 and 3 L
i ENCLOSURE 1 REFERENCES MNSA Code Replacement Request for Relief
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I ENCLOSURE 1 REFERENCES 1)
Letter from William H. Bateman (U.S. NRC) to Harold B. Ray (SCE), dated January 29,1999;
Subject:
Use of the Mechanical Nozzle Seal Assembly for the San Onofre Nuclear Generating Station, Units 2 and 3 (TAC Nos. MA1776 and MA1777) 2)
Letter from J. L. Rainsberry (SCE) to Document Control Desk (U.S. NRC), dated November 18,1998;
Subject:
Docket Nos. 50-361 and 50-362, Use of the Mechanical Nozzle Seal Assembly, San Onofre Nuclear Generating Station, Units 2 and 3 (TAC Nos. M99558 and M99599) 3)
Letter from A. E. Scherer (SCE) to the Document Control Desk (NRC), dated May 24,1999;
Subject:
Owners Report of Inservice Inspection, Form NIS-1, San Onofre Nuclear Generating Station Unit-2,(Docket No. 50-361).
4)
Letter from A. E. Scherer (SCE) to the Document Control Desk (NRC), dated August 5,1999;
Subject:
Owners Report of Inservice inspection, Form NIS-1, San Onofre Nuclear Generating Station Unit-3,(Docket No. 50-361 (sic)).
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Relief Request l
i MNSA - Cycle 11 1
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1 ENCLOSURE 2 RELIEF REQUEST MNSA-CYCLE 11
. San Onofre Nuclear Generating Station Unit 2 (Docket 50-361) and Unit 3 (Docket 50-362)
SYSTEM:
' COMPONENT / AREA:
Instrument Nozzles: Piping,~ Pressurizer, Steam Generator CODE CLASS:
1 CODE APPLICABILITY:
ASME Code Section XI, IWA-7000 Replacement, 1989 Edition with no Addenda j
DESCRIPTION Use of the Mechanical Nozzle Seal Assembly (MNSA)
Alternate Method for Replacing Reactor Coolant System Instrument Nozzles CODE REQUIREMENTS Per Section XI, IWA 7200, any items used for replacement shall meet the original Construction Code requirements. Use of a j
later edition of the Construction Code is alkwed provided that a l
Code date reconciliation is performed to show that the j
replacement item meets the design requirements.
i Components which are part of the reactor coolant pressure boundary must meet the requirements for Class 1 components in Section lli d the ASME Boiler and Pressure Vessel Code as stated in 10 CFR 50.55a(c)(1).
REQUESTED RELIEF Stress Corrosion Cracking has been experienced in the inconel 600 nozzles at many nuclear plants. The typical repair of these nozzles involves external weld repairs or half nozzle F
replacements. The MNSA would be used as an alternative
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replacement to repair leaks or where there may be susceptibility to leaking in RCS nozzles.
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BASIS FOR RFllEF Tile Mechanical Nozzle Seal Assembly (MNSA) provides the leakage sealing function plus
. structural integrity of a nozzle attachment weld in locations (e.g., bottom of the pressurizer) where the typical repair and replacement techniques may be difficult or impractical.
Installation of the MNSA will also avoid the need for higher risk plant operations (i.e.,
' reduced inventory or core offloads for repair or replacement of RCS nozzles). In addition, the MNSA vfill shorten the repair or replacement time significantly and thereby reduce radiation exposure to workers.
A radiation exposure savings from use of the MNSA instead of the present nozzle repair / replacement method is expected to be approximately 1 person-rem per steam generator nozzle and approximately 1.5 to 2 person-rem per nozzle on the pressurizer.
Additionally, the removal of the currently installed MNSAs and subsequent nozzle repair would result in approximately 2 person-rem per nozzle.
BACKGROUND By letter dated January 29,1999, Reference A, the NRC approved interim use of the
' MNSAs. This approval was based on several SCE submittals, References B,C,D,E,F and G.
DISCUSSION The design information provided by SCE in References B,C,D,E,F, and G is still applicable and supports the use of the MNSAs at SONGS for the period of operation beginning with the Cycle 11 refueling outage through the Cycle 12 refueling outage, which is Cycle.11.
This use of the MNSAs is further supported by the inspection results ot' the MNSAs which
- was conducted during the Cycle 10 refueling outage. The results of the inspections were satisfactory, and a summary of the visual examination results was included in references H and I. - The satisfactory inspection results support the continued use of the MNSAs at
. SONGS.
~ Furthermore, SCE reaffirms and updates the following commitments originally made in Reference Gi 1)
- SCE will request cycle by cycle approval from the U.S. NRC to operate with MNSAs installed.
This SCE request is for U.S. NRC approval to use the MNSAs in both Units 2 and 3 until the end of the Unit 2 and the Unit 3 Cycle 12 refueling outages (currently planned for 2002).
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After the completion of the Cycle 11 refueling outages for Unit 2 l
(currently planned for 2000) and Unit 3 (currently planned for 2001),
l and prior to the Cycle 12 refueling outage for Unit 2, SCE will submit another request to use the_MNSAs:. both Units 2 and 3 until the end of the Unit 2 and Unit 3 Cycle 13 ret ling outages (currently planned for 2004).
SCE will perform and document the visual inspections each refueling outage as specified in Reference F.
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During the Cycle 12 refueling outages, SCE will remove all MNSAs and replace them.
The MNSAs removed will be examined for any evidence of corrosion.
The information gathered by this examination will be used to support the request for permanent use of the MNSAs on the Pressurizer s
instrument nozzles and the Steam Generator channel head instrument nozzles.
References:
' A)
. Letter from William H. Bateman (U.S. NRC) to Harold B. Ray (SCE),
dated January 29,1999;
Subject:
Use of the Mechanical Nozzle Seal Assembly for the San Onofre Nuclear Generating Station, Units 2 and 3
- (TAC Nos. MA1776 and MA1777)
B)
Letter from J. L. Rainsberry (SCE) to Document Control Desk (U.S. NRC),
dated July 11,1997; subject Mechanical Nozzle Seal Assembly Code Replacement Request for Relief from 10 CFR 50.55a, San Onofre Nuclear Generating Station, Units 2 and 3.
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Letter from J. L. Rainsberry (SCE) to Document Control Desk (U.S. NRC)
C dated Deamber 12,1997;
Subject:
Docket Nos. 50-361 and 50-362, Mechanic 61 Nozzle Seal Assembly Code Replacement, Request for Relief l
from 10 CFR 50.55a, San Onofre Nuclear Generating Station, Units 2 and 3.
D)-
Latter from J. L. Rainsberry (SCE) to Document Control Desk (U.S. NRC) dated January 5,1998;
Subject:
Mechanical Nozzle Seal Assembly Code Replacement
- Request for Relief from 10 CFR 50.55a, San Onofre Nuclear Generating Station, Units,2 and 3. (TAC Nos. M99558 and M99559)
L-
l E)
Letter from J. L. Rainsberry (SCE) to Document Control Desk (U.S. NRC),
dated January 29,1998;
Subject:
Mechanical Nozzle Seal Assembly Code Replacement Request for Relief from 10 CFR 50.55a, San Onofra Nuclear.
Generating Station, Units 2 and 3. (TAC Nos. M99558 and M99559)
F)
Letter from J. L. Rainsberry (SCE) to Document Control Desk (U.S. NRC),
dated April 30,1998;
Subject:
Docket Nos. 50-361 and 50-332, Use of the Mechanical Nozzle Seal Assembly, San Onofre Nuclear Generating Station, Units 2 and 3 (TAC Nos. M99558 and M99599)
G)
Letter from J. L. Rainsberry (SCE) to Document Control Desk (U.S. NRC),
dated November 18,1998;
Subject:
Docket Nos. 50-361 and 50-362, IJse of the Mechanical Nozzle Seal Assembly, San Onofre Nuclear Generating Station, Units 2 and 3 (TAC Nos. M99558 and M99599)
)
H)
Letter from A. E. Scherer (SCE) to the Document Control Desk (NRC),
dated May 24,1999;
Subject:
Owners Report of Inservice Inspection, j
Form NIS-1, San Onofre Nuclear Generating Station Unit-2,(Docket No.
50-361).
l I)
Letter from A. E. Scherer (SCE) to the Document Control Desk (NRC),
dated August 5,1999;
Subject:
Owners Report of inservice inspection,
- Form NIS-1, San Onofre Nuclear Generating Station Unit-3, (Docket No.
50-361[ sic]).
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