ML20101M646
| ML20101M646 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 06/30/1992 |
| From: | J. J. Barton GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| C321-92-2194, GL-92-01, GL-92-1, NUDOCS 9207080337 | |
| Download: ML20101M646 (6) | |
Text
..a GPU Nuclear Corporation gd S Nuclear
- =:ree Forked River, New Jersey 08731-0388 609 971-4000 Writer's Dwect D;al Number:
June 30, 1992 C321-92-2194 U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, DC 20555 Gentlemen:
Subject:
Oyster Creek Nuclear Generating Station Docket No. 50-219 l
GPUN Response to Generic Letter (GL) 92-01 Revision 1, " Reactor Vessel Structural Integrity"
Reference:
1.
ASME Code Case N-xxx ' Assessment of Reactor Vessels with Low Upper Shelf Charpy Energy Levels", Rev.10 datad April 17, 1992.
2.
GPUN letter, "Unirradiated Upper Shelf Energy Values for Reactor Vessel Beltline Welds", dated July 17, 1991, from DeVine of GPUN to NRC.
3.
NRC letter, " Upper Shelf Energy Values for Reactor Vessel Beltline Welds. - Oyster Creek Nuclear L,.1erating Station (TAC No. 81060)", dated August 22, 1991, from Dromerick of NRC to Barton of GPUN.
4.
GPUN letter, "0yster Creek Nuclear Generating Station (OCNGS), Docket No. 50-219 Technical Specification Change Request No. 194", dated January 11, 1991, froa Barton of GPUN to NRC.
L On March 6, 1992, NRC issued Generic Letter 92-01, Revision 1, " Reactor Vessel Structural Integrity" and r equested licensees within 120 aays of the date of issuance o-to provide certain information regarding Appendices 4 and G to 10 CFR Part 50, and
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Our responses to the request are provided bel u.
28a-
. go 1.
Information reauested bY GL 92-01 regarding Appendix H to 10 CFR Part 50:
oo NRC Reauest:
sg no
$8 Addressees who do not have a surveillance program meeting ASTM
$4 E 185-73,
-79, or -82 and who do nyt have an integrated N
surveillance program approved by the NRC are requested to OE describe actions taken or to be taken to ensure compliance with f
en.a.
Appendix H to 10 CFR Part 50. Addressees who plan to revise the
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C'321-92-2194 Page 2 surveillance program to meet Appendix H to 10 CFR Part 50 are requested to indicate when the revised program will be submitted to the NRC staff for review. If the surveillance program is not to be revised to meet Appendix H to 10 CFR Part 50, addressees are requested to indicate when they plan to request an exemption from Appendix H to 10 CFR Part 50 under 10 CFR 50.60(b).
GPUN R63Donse:
Since Oyster Creek was built prior ta the issuance of ASTM E185-73, the surveillance program does not comply with ASTM E185-73.
However, the deviations have been reviewed by the NRC staff per NUREG-0569
(" Evaluation of the Integrity of SEP Reactor Vessel").
In their evaluation, the staff concluded that the surveillance program meets the intent of Appendix H to 10 CFR Part 50 without revision and is acceptable.
Oyster Creek is also one of the host plants for BWR owners group (BWROG) supplemental surveillance program which exceeds the requirements of Appendix H to 10CFR50. Three new surveillance capsules are planned to be installed in the reactor vessel during the upcoming 14R refueling outage which is scheduled to commence in January, 1993.
2.
Information reauested by GL 92-01 reoardina Appendix G to 10 CFR Part 50:
NRC Reauest:
a.
Addressees of plants for which the Charpy upper shelf energy is predicted to be less than 50 foot-pounds at the end of their licenses using the guidance in Paragraphs C.I.2 or C.2.2 in Regulatory Guide (RG) 1.99, Revision 2, are requested to provide to the NRC the Charpy upper shelf energy predicted for December 16, 1991, and for the end of their current license for the limiting beltline weld and for the plate or forging and are requested to describe the actions taken pursuant to Paragraphs IV.A.1 or V.C of Appendix G to 10 CFR Part 50.
GPUN Response:
The unirradiated upper shelf energies (USE) of the beltline plates were developed based on the charpy tests of long:tudinally-oriented specimens.
The lowest unirradiated lcaottudinal USE is 79 ft-lb for beltline plate G-8-7.
The predici.ed USE at 1/4T (T= reactor vessel beltline thickness) for this material is 62 ft-lb at 32 effective full power years (EFPY) according to Regulatory Guide (RG) 1.99, Rev. 2.
During a recent telephone conversation on May 7, 1992 and at a subsequent meeting with the NRC staff on May 23, 1992, GPUN presented the preliminary results of low USE analysis which demonstrated the adequacy for continued service of beltline plates. This ana?ysis is based on the theory of elastic-plastic
.C'321-92-2194 Page 3 fracture mechanics and used the methods approved by the ASME Section XI Working Group on Flaw Evaluation (Ref.1). The USE used in the analysis is the converted transverse USE (65% of longitudinal USE) based on the guidelines specified in Section 5.3.2 " Pressure-Temperature Limits" of the Standard Review Pl an. Three beltline plates would currently have lower than 50 ft-lb transverse USE if the 65% conversion # actor were used. The lowest predicted transverse USE would be 42.9 ft-lb on December 16, 1991. However, based on our analysis, which will be submitted to the staff for their review on a later date, as low as 35 ft-lb transverse USE still would be acceptable.
The USE of beltline welds has been evaluated and accepted by the NRC staff per References 2 and 3.
The lowest predicted USE is 55 ft-lb at 32 EFPY, which meets the requirements of Appendix G to 10 CFR Part 50.
b.
Addressees whose reactor vessels were constructed to an ASME Code earlier than the Summer 1972 Addenda of the 1971 Edition are requested to describe the consideration given to the following material properties in their evaluations performed pursuant to 10 CFR 50.61 and Paragraph III.A of 10 CFR Part 50, Appendix G:
NRC Reauest:
(1) the results from all Charpy and drop weight tests for all unirradiated beltline materials, the unirr adiated reference temperature for each beltline material, and the method of determining the unirradiated reference temperature from the Charpy and drop weight test, GPUN Response:
All the required information has been submitted to the NRC in Reference 4.
The drop weight tests were not performed on beltline materials. Therefore, the nil ductility temperature of beltline material is not available.
NRC Reauest:
(2) the heat treatment received by all beltline and surveillance materials; GPUN Response:
The beltline olates were heat treated at 1550 - 1600 F for four hours, water quenched and tempered at 1200 - 1250 F for an additional four hours. The final postweld heat treatment (PWHT) was performed at 1150 25 F for ten and one half hours.
The heat treatment for surveillance plate specimens is the same as that of beltline plates with additional heat treatment of 1150 25 F for thirty hours.
The time for PWHT (1150 25 F) of surveillance welding specimens is forty hours.
l
- C'321-92-2194 Page 4 NRC Reouest:
(3).the heat r, umber for each beltline plate or forging and the heat i
number of wire and flux lot number used to fabricate each beltline weld; GPUN ResDonse:
The information requested was sent to the NRC in References 2 and 4.
NRC Recuest:
(4) the heat number for each surveillance plate or forging and the heat number of wire and flux lot number used to fabricate the surveillance weld; GPUN ResDonse:
The heat number of surveillance plate is T1937-1, which is the same as that of beltline plate G-308-1 (Ref. 4). The heat and flux numbers of surveillance weld have been sent to the NRC per Ref. 2.
NRC Reauest:
(5) the chemical composition, in particular the weight in percent of copper, nickel, phosphorous and sulfur for each beltline and surveillance material; NRC Reauest:
(6) the heat number of the wirc used for determining the weld metal chemical composition if different than Item (3) above.
GPUN ResDonse to Items (5) & (6):
The information requested has been sent to the NRC in References 2 and 4.
3.
Information requested by GL 92-01 regarding commitments made to respond to GL 88-11:
NRC Reauest:
a.
How the embrittlement effect of operating at an irradiation temperature (cold leg or recirculation suction temperature) below 525 F were considered.
In particular, licensees are requested to describe consideration given to determining the effect of lower irradiation temperature on the reference temperature and on the Charpy upper shelf enc-rgy.
' C321-92-2194 Page-5 GPUN Response:
The embrittlement effects of operating at an irradiation temperature below 525 F were not considered to be significant because the steady operating temperature is greater than 525*F.
Only during startup and operation without feedwater heating would-the beltline experience coolant less than 525 F when the core is critical. This could happen when feedwater heaters are out of service or when the turbine is off line and the reactor steam is routed through the turbine bypass.
The time of operation in these transient conditions has been estimated to be lessthan1%,andtheassociatedtemperatureformostof} hat 18 time are higher than 515*F.
The fluence is 2.36x10 n/cm at 32 [FPY, so the fluence accumulated below 525 F would be 2.36 x 10' n/cm. The combination of low fluence and small deviation from the 525 F level are not expected to significantly affect beltiine P.T., or USE predictions.
NRC Recuest:
b.
How their surveillance results on the predicted amount of embrittlement were considered.
GPUN Response:
Oyster Creek has only one credible surveillance data set.
Therefor e, the predicted amount of embrittlement is based on position 1.1 or RG 1.99, Rev. 2, i.e., without the consideration of surveillance results.
NRC Recuest:
c.
If a measured increase in reference temperature exceeds the mean-plus-two standard deviations predicted by Regulatory Guide 1.99, Revision 2, or if a neasured decrease in Charpy upper shelf energy exceeds the value predicted using the guidance in Paragraph C.l.2 in Re]ulatory Guide 1.99, Revision 2,
the licensee is requested to report the information and describe the effect of the surveillance results on the adjusted reference temperature and Charpy upper shelf energy for each beltline material as predicteo for December 16, 1991 and for the end of its current license.
GPUN Response:
The measured increases in reference temperature (RTey) and decreases in USE are within the mean-plus-two standard deviations predicted by pb 1.99, Rev. 2 for surveillance plate.
Since Oyster Creek hs only one set of surveillance data and the original full Charpy curve is not available for surveillance
'I C321-92-2194 Page 6-weld, it is inappropriate to judge the change of reference temperature and USE with the values predicted by RG 1.99, Rev.
2 at this time.
If you have any questions concerning the information provided in this letter, please contact Mr. Michael Laggart, Manager - Corporate Licensing at (201) 316-7968.
- incerely, 5
J hn J.
ar on ice Pr > ent & Director Oyster Creek JJB/YN:lga cc: Administrator, Region 1 Oyster Creek NRC Project Manager Oyster Creek Senior Resident Inspector i
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