ML20101N135
| ML20101N135 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/02/1992 |
| From: | Broughton T GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| C311-92-2086, GL-92-01, GL-92-1, NUDOCS 9207090176 | |
| Download: ML20101N135 (4) | |
Text
.
l i
~ENuclear
= o m m 'eo GPU Nuclear Corporation o
Middletown. Pennsylvania 17o57 0191 717 944 7621 TELEX 84 2386 Writer's Difett Dial Nurnt>er; (717) 948-8005 July 2, 1992 C311-92-2086 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Gentlemen:
Subject:
Three Mlle Island flucicar Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 GPUN Response to Generic Letter (GL) 92-01 Revision 1, " Reactor Vessel Structural Integrity"-
On March 6, 1992, NRC issued Generic Letter 92-01, Revision 1, " Reactor Vessel Structural Integrity" and requested licensees to provide certain information regarding Appendixes H and G to 10 CFR Part 50, and Generic letter 88-11 within 120 days of the date of the issuance.
On June 17, 1992, a report entitled " Response to Generic Letter 92-01" (BAW-2166) was submitted by the B & W Owners Group (B&WOG) on behalf of the B & W Owners Group Reactor Vestel Working Group.
The report provides the information requested in Generic Letter 92-01 for B&W Owners Group (B&WOG) 31 ants, including Three Mile Island Nuclear Generating Station Unit 1.
We lave reviewed the report and concur with its content; however, the following information is provided for additional clarification of the status of the l
THI-l reactor vessel.
l The B&WOG report utilized Regulatcry Guide (R.G.) 1.99 Rev. 2, paragraph C.I.2 as the basis for responding to item 2a of the Generic Letter.
The report L
established the WF-25 circumferential weld to have the lowest Charpy Upper l
Shelf Energy (CV-USE), and is therefore defined to be the limiting weld.
0-Appi1 cation of paragraph C.2.2 of the Regulatory Guide to the B&WOG r$$
surveillance data indicates that the TMl-1 vessel contains two additional R8' welds which exhibit similar degradation behavior of the Cv-USE.
These weld gg materials are SA-1526 and WF-70 which are longitudinal and circumferential no welds, respectively, h
Review of the B&WOG surveillance Cv-USE data for the weld wires from which og these three welds were made would indicate that prediction of the Cv-USE per R.G. 1.99 Rev. 2, paragraph C.I.2 would yield a very conservative lower bound 6
to the actual data. Application of R.G. 1.99 Rev. 2, paragraph C.2.2 for g'o predicting the Cv-USE also conservatively bounds the surveillance data and jlo1Qogngresults:
yields,t,h f
GPU Nuclear Corporation is a subsidiary of General Pubhc Utihties Corporation
C311-92-2086 Page 2 I
Status or g U g G r
Weld Metal SA - 1526 WF - 25 WF - 70 Weld Orientation Longitudinal Circumferential Circumferential Initial tv-USE 70 ft-Lbs 70 Ft-Lbs 70 Ft-Lbs Percent Copper Actual Chemistry 0.35 %
0.35 %
0.35 %
Effective Copper 0.256 %
0.256 %
0.29 %
based on R.G.
1.99 Para. C.2.2 i
Cv-USE per R.G. 1.99 Rev. 2, paragraph C.2.2 EFPY at 14 EFPY 13 EFPY 9 EFPY Cv-USE<50 ft-lbs Dec. 16, 1991 51.7 ft-Lbs 51.4 ft-Lbs 50.2 Ft-Lbs (8.1 EFPY) 9 EOL (2014) 47.4 47.1 45.7 26.17 EFPY 9 32 EFPY 46.5 46.2 44.7 (2021) l These results-indicate'that the Cv-USE for circumferential weld WF-70 may fall below the 50 Ft-Lbs level in the fourth quarter of this year.
This class of weld metals exhibits an apparent saturation of the irradiation induced degradation.
Thus, the Cv-USE decrease tends to level off at _ higher fluences.
As stated in the B&WOG report, an analysis per 10 CFR 50, App. G Section V.C.3 is-scheduled for 1993 as an owners group activity.
The following information-supports extension of the submittal 'date for a THI-l plant specific analysis until 1993. The B&WOG Reactor Vessel Integrity Program has already completed and submitted'such-analysis to the NRC for two lead Plants.
The analysis for one of these plants, submitted by B&WOG report-BAW-2148P Rev.1, evaluated the Cv-VSE of weld metal WF-70.
It is_ apparent that this analysis would bound the THI-1 plant specific analysis results for the WF-70 circumferential weld, A comparison of the analytical inputs utilized in-BAW-2148 versus the-THI-l vessel is presented to illustrate this point. This comparison permits 4-conclusion that the Lead Plant analysis results can be~ expected to-bound the results for the THI-1 WF-70 weld.
a.-
u--
C311-92-2006 Page 3 Comparison of Low Cv-USE Evaluation Analysis inputs B&WOG Lead Plant THI-l Weld Metal WF-70 WF-70 Fluence 0 1/4T 9.34E18 4.0E18 9 EOL Weld Orientation Longitudinal Circumferential Design Pressure 2485 2500 (psig)
Vessel ID (Inches) 173 171 Vessel Wall 8.44 8.438 Thickness (Inches)
Cold leg Operating 530 555 Temp. (*F)
This com)arative table indicates that the only major difference in the inputs for the 31WOG Lead plant analysis and one which would be performed for TMI-l is the weld orientation. However, the )rimary loading due to pressure for the circumferential weld orientation would ae approximately one half of the value contained in the Lead Plant analysis for the longitudinal weld.
Thus, the Lead Plant analysis bounds the results of analysis for THI-1.
The B&WOG report plus the supplementary information contained herein provides the status of TM1-1 com)11ance with the recuirements of Appendices G and 11 to 10 CFR Part 50.
TMl-1 las also implementet significant flux reductions by prudent fuel management and is an active participant in the B&WOG Reactor Vessel Integrity Program to maintain vigilance of the status of the vessel:
embrittlement.
THI-l has completed its 10 year ISI of the vessel utilizing the B&W enhanced inspection technique to demonstrate the absence of significant flaws within the vessel wall.
Based on the above, adequate margin of safety against fracture exists for the THI-l reactor vessel, if you have any questions concerning the information provided, please contact Mr. Michael Laggart, Manager, Corporate Nuclear Licensing at (201) 316-7968.
Sincerely, db
/A T. G. Bro ghton-Vice President;and Director, THI-l YN:1ga cc: Administrator, Region I THI-l Senior Project lianager TMI Senior Resident inspector a
e C311-92-2086 HElROPOLITAfl EDISON COMPANY JERSEY CENTRAL POWER AND LIGHT COMPANY PENHSYLVANIA ELECTRIC COMPANY GENERAL PVOLIC VIILITIES NVCLEAR CORPORATION Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Response to the Generic Letter 92-01, Revision 1 Reactor Vessel Structural Integrity This letter is submitted to provide clarification of the status of the THI-l Reactor Vessel.
This information is in addition to the B&W Owners Group response (BAW-2166) to Generic letter 92-01, Revision 1, 10 CFR 50.54(f)
Request
" Reactor Vessel Structural Integrity." All statements contained in this response have been reviewed, and all such statements made and matter 5,et forth therein are true and correct to the best of my knowledge, hlUngl4~
T. G. Broughton Vice President and Director, THI-l Signed and swarn before me this 2nd day of July
, 1992.
tw O\\
. neto Notary Pbblic N
w nma --