ML20206R242
| ML20206R242 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 01/13/1999 |
| From: | Scherer E SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-97-01, GL-97-1, TAC-M98593, TAC-M98594, NUDOCS 9901190200 | |
| Download: ML20206R242 (11) | |
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- 4. ro-o se-l l9' EDISON "1-m An uusm imamosu - cow-y January 13, 1999 l
U. S. Nuclear Regulatory Commission l
Attention: Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Docket Nos. 50-361 and 50-362 Request for Additional Information Regarding Generic Letter 97-01:
" Degradation of Control Rod Drive Mechanism Nozzle and Other Vessel Head Penetrations" (TAC Nos. M98593 and M98594)
San Onofre Nuclear Generating Station Units 2 and 3
References:
See Enclosure 1 This letter provides the additional information concerning Generic Letter (GL) l 97-01 requested in the September 14, 1998, NRC letter to the Southern l
California Edison Company (SCE), reference 1, for the San Onofre Nuclear l
Generating Station (SONGS), Units 2 and 3.
The specific responses to the l
request for additional information are contained in Enclosure 2 to this letter; the answers refer the reader to the generic industry response, reference 2.
This letter also serves to inform the NRC that SCE is revising the inspection plans previously provided to the NRC by references 3 and 4.
Request fcr Additional Information l
l The NRC has encouraged a generic industry response to this issue. The Nuclear Energy Institute (NEI) Project Number 689, " Generic Responses to the NRC l
Requests for Additional Information on Generic Letter 97-01," has been submitted unkr separate cover to the NRC by the NEI.
The SCE response to the request for additional information references the appropriate section of the HEI response, specifically, Enclosure 4 of the NEI l
response, which provides the Combustion Engineering Owners Group response to the NRC requests for additional information, O
9901190200 990113 PDR ADOCK 05000361 P
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San Clemente, CA 92074-0128 949-368-7501 rat 949-368-7575
l Document Control Desk i Inspection Schedule
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References 3 and 4 address SCE's previous plans to perform an eddy current examination of 100% of the reactor vessel head penetrations (including 91 control rod drive mechanism nozzles,10 encore instrumentation,ozzles, and the reactor head vent penetration) during the Cycle 10 refueling outages.
l SCE remains committed to performing eddy current examinations of 100% of the reactor vessel head penetrations at San Onofre Unit 3.
SCE believes, however, that the timing of the examinations should meet several objectives.
l Primarily, the timing of the examinations must help ensure reactor safety.
Also, SCE feels that the timing should maximize, as much as reasonably l
possible, the chances of detecting any degradation prior to the need for a l
repair method that would require welding.
Finally, and within the bounds of l
l the first two objectives, SCE believes that it would be advantageous to develop and apply an effective mitigation strategy to reduce or eliminate the need for future examinations.
l In addition, based on the following considerations, SCE will not be performing eddy current examinations during the Cycle 10 refueling outages (early 1999) l for Units 2 and 3:
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1.
The EPRI model places all plants in three categories based on the time i
remaining to reach the NEI benchmark crack depth:
lessthan5yearsfrom1/1/97.
between5and15yearsfrom1/1/97(SONGS 3isinthiscategory).
l greaterthan15yearsfrom1/1/97(SONGS 2isinthiscategory).
The EPRI model runs completed to date indicate that SONGS 3 will not experience cracking which would exceed the NEI benchmark crack depth prior to 1/1/2002,(i.e.,fiveyearsafter1/1/97).
2.
SCE believes that delaying the examination does not constitute a safety risk.
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l Document Control Desk As.a result, SCE will:
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1) perform eddy current examinations of 100% of the reactor vessel head penetrations at San Onofre Unit 3 at a time that meets the objectives stated above, 2) continue to perform visual inspections of the periphery reactor vessel head penetration nozzles during each refueling outage for both Units 2 l
and 3, l
r 3) keep the NRC informed of the future plans for eddy current examinations l
at Unit 3 on a cycle by cycle basis, and l
4) work toward the development of a mitigation technique.
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If you have any questions or would like additional information regarding Ciis issue, please let me know.
Sincerely, s
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Enclosures cc:
E. W. Merschoff, Regional Administrator, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 J. W. Clifford, NRC Project Manager, San Onofre Units 2 and 3 l
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9 ENCLOSURE 1 References l
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References:
1)
Letter from James W. Clifford (NRC) to Harold B. Ray (SCE), dated September 14, 1998;
Subject:
Request for Additional Information Regarding Generic Letter 97-01: " Degradation of Control Rod Drive Mechanism Nozzle and Other Vessel Head Penetrations") For San Onofre Nuclear Generating Station Units 2 and 3 (TAC Nos. M98593 and M98594) 2)
Letter from D. J. Modeen ((NEI) to G.C. Lainas (NRC), dated December 11, l
1998;
Subject:
" Responses to the NRC Requests for Additional Information on Generic Letter 97-01" l
3)
Letter from J. L. Rainsberry (SCE) to the Document Control Desk (NRC),
dated August 6,1997;
Subject:
120 Day Response to Generic Letter 97-01:
" Degradation of Control Rod Drive Mechanism Nozzle and Other Vessel Head l
Penetrations," San Onofre Nuclear Generating Station Units 2 and 3 4)
Letter from D. E. Nunn (SCE) to A. i. Howell III (NRC) dated October 31, l
1997;
Subject:
Docket Nos. 50-361 and 50-362, San Onofre Nuclear l
Generating Station, Units 2 and 3 l
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ENCLOSURE 2 The Southern California Edison Company (SCE)
Response to the NRC Requested Information Concerning Generic Letter 97-01 l
for San Onofre Units 2 and 3 1
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I ENCLOSURE 2 The Southern California Edison Company (SCE)
Response to the NRC Requested Information Concerning Generic Letter 97-01 for San Onofre Units 2 and 3 NRC REQUESTED INFORMATION Designate which crack susceptibility model is being endorsed for the assessment of CEDM penetratton nozzles at your plant.
SCE RESPONSE Nuclear Energy Institute (NEI) Project Number 689, " Generic Responses to the NRC Requests for Additional Information on Generic Letter 97-01," has been submitted under separate cover to the NRC by the NEI.
The NRC has encouraged a generic industry response to this issue. Therefore, the Combustion Engineering Owners Group (CEOG) has developed a generic response.
The response to this question is included in Enclosure 4, "CE0G Response to NRC Requests for Additional Information," of the NEI generic response, particularly the Response to Question 1 therein.
l NRC REQUESTED INFORMATION Indicate how the susceptibility model being endorsed relates to the CEOG's integrated program for assessing the CEDM penetration nozzles at ABB-CE designed j
plants, and whether or not the design of the susceptibility model is consistent i
with the contents of Topical Report CE NPSD-1085.
SCE RESPONSE Nuclear Energy Institute (NEI) Project Number 689, " Generic Responses to the NRC Requests for Additional Information on Generic Letter 97-01," has been submitted under separate cover to the NRC by the NEI.
The NRC has encouraged a generic l
industry response to this issue. Therefore, the Combustion Engineering Owners l
Group has developed a generic response.
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The response to this question is included in Enclosure 4, "CE0G Response to NRC Requests for Additional Information," of the NEI generic response, particularly the Response to Question 2 therein.
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4 Responses to the NRC Requested Information 2
Concerning Generic Letter 97-01 NRC REQUESTED.INFORMATION If the ABB-CE PITM model is being endorsed for the assessment of CEDM penetration nozzles at your plant, address items o. - e. below.
If the PITM models are beina endorsed for the assessment of your CEDEgenetration nozzles.-
a.
Provide an expanded discussion and additional details describing how the time to-failure model in the PITM relates to the PITM's time-to-1 initiation model.
In particular, include on expended discussion of how the PITM model relates growth of postulated flows to the time-to-initiation model, and how the two aspects relate to each other and to the probability of foilure methodology.
l b.-
Provide the latest PITM susceptibility ranking of CEDM penetration l
nozzles and, if applicable, of the vessel head instrumentation nozzles at your plant relative to the rankings of those at the other CEOG member plants.
c.
Provide a description of how the PITM model for assessing postulated flows in vessel head penetration nozzles was bench-marked, and list and discuss the standards the'models were bench-marked against.
d.
Provide any additional Information regarding how the model will be refined to allow the input of plant-specific inspection data into the model's analysis methodology.
e.
Describe how the variability in the product forms, material specifications, and heat treatments used to fabricate each CEDM penetration nozzle at the CEOG member utilities are addressed in the PITM l
model.
SCE RESPONSE Nuclear Energy Institute (NEI) Project Number 689, " Generic Responses to the NRC
. Requests for Additional information on Generic Letter 97-01," has been submitted under separate cover to the NRC by the NEI.
The NRC has encouraged a generic industry response to this issue. Therefore, the Combustion Engineering Owners i
Group (CE0G) has developed a generic response, i
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I Responses to the NRC Requested Information 3
Concerning Generic Letter 97-01 The response to this question is included in Enclosure 4, "CE0G Response to NRC Requests for Additional Information," of the NEI generic response, particularly the Response to Question 1 therein. As stated therein, the CE0G now endorses the use of the EPRI model for the assessment of primary water stress corrosion cracking (PWSCC) in Alloy 600 reactor vessel head penetrations.
Therefore no further response to items a. - e. is necessary.
NRC REQUESTED INFORMATION If the Dominion Engineering susceptibility model is being endorsed for the assessment of CDM penetration nozzles at your plant, address items f - i. below.
If the susceotibility.model develooed by Dominion Enaineerin is beina endorsed
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for the assessment of Your CDM-Penetration nozzles.-
f.
Provide a description of how the various product forms, material specifications, and heat treatments used to fabricate each CDM penetration nozzle at the CEOG member utilities are handled in the j
Ocminion Engineering susceptibility model.
SCE RESPONSE l
l f.
Nuclear Energy Institute (NEI) Project Number 689, " Generic Responses to l
the NRC Requests for Additional Information on Generic Letter 971," has been submitted under separate cover to the NRC by the NEI.
The NRC has encouraged a generic industry response to this issue.
Therefore, the i
Combustion Engineering Owners Group has developed a generic response.
The response to this question is included in Enclosure 4, "CE0G Response to NRC Requests for Additional Information," of the NEI generic response, particularly the Response to Question 3 therein.
NRC REQUESTED INFORMATION I
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Provide any additional information, if available, regarding how the model f
will be refined to allow the input of plant-specific inspection data into the mcdel's analysis methodology, i
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4 Responses to the NRC Requested Information 4
Concerning Generic Letter 97-01 SCE RESPONSE
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Nuclear Energy Institute (NEI) Project Number 689, " Generic Responses to the NRC Requests for Additional Information on Generic Letter 971," has been submitted under separate cover to the NRC by the NEI.
The NRC has J
encouraged a generic industry response to this issue.
Therefore, the l
Combustion Engineering Owners Group has developed a generic response.
The response to this question is included in Enclosure 4, "CE0G Response to NRC Requests for Additional Information," of the NEI generic response, particularly the Response to Question 5 therein.
NRC REQUESTED INFORMATION h.
Describe how the Dominion Engineering crack initiation and crack growth models for assessing postulated flaws in vessel head penetration nozzles
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were benchmarked, and provide a listing and discussion of the standards the models were bench-marked against.
SCE RESPONSE h.
Nuclear Energy Institute (NEI) Project Number 689, " Generic Responses to l
the NRC Requests for Additional Information on Generic Letter 971," has been submitted under separate cover to the NRC by the NEI.
The NRC has encouraged a generic industry response to this issue.
Therefore, the Combustion Engineering Owners Group has developed a generic response.
l The response to this question is included in Enclosure 4, "CE0G Response to NRC Requests for Additional Information," of the NEI generic response, particularly the Response to Question 4 therein.
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NRC REQUESTED INFORMATION I
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Provide the latest model susceptibility rankings of CDM penetration nozzles in CEOG member plants based on the results of the Dominton l
Engineering susceptibility model analyses of these CDM and ICI nozzles.
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Responses to the NRC Requested Information 5 Conceining Generic Letter 97-01 l
SCE RESPONSE l
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Nuclear Energy Institute (NEI) Project Number 689, " Generic Responses to the NRC Requests for Additional Information on Generic Letter 971," has been submitted under separate cover to the NRC by the NEI.
The NRC has
' encouraged a generic industry response to this issue.
Therefore, the Combustion Engineering Owners Group has developed a generic response.
l The response to this question is included in Enclosure 4, "CE0G Response to NRC Requests for Additional Information," of the NEI generic response, particularly the Response to Question 6 therein.
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