ML20101N479
| ML20101N479 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 07/03/1992 |
| From: | Pelletier J VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BVY-92-76, GL-92-01, GL-92-1, NUDOCS 9207090352 | |
| Download: ML20101N479 (10) | |
Text
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.VEItMONT YANKEE NUCLEAR POWER CORPORATION
.Nx Ferry Road, Brattleboro, VT 05301 7002
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ENGINE IN OFFICE d'
sea u Ais strm rmos eme July 3,1NI""
iJnited States Nuclear Regulatory Conunission BVY 92 - 76 ATTN: Document Control Desk Washington, DC 20555
References:
a.
License No. DPR-28 (Docket No. 50-271) b.
letter, J.G. Panlow (USNRC) to [All Licensees], NVY 92-041, dated Maah 6,1992 (Generic Letter 92-01, Revision 1)
Stbject:
Vermont Yankee Response to Generic Letter 92-01 Regarding Reactor Vessel StructuralIntegrity
Dear Sir:
Enclosed please find Vermont Yankee's response to Generic Letter 92-01 [ Reference (b)],
which requimd a response pursuant to 10CFR50.54(f) within 120 days of issuance.
Should you have further questions with regard to the enclosed information, please contact this office.
Very truly yours, VERMONT YANKEE NUCl. EAR POWER CORPORATION ames P. Pelletier Vice President - Engineering cc:
USNRC Region 1 Administrator USNRC Resident Inspector-VYNPS USNRC Project Manager-VYNPS STATE OF VERMONT
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$m nen personally appeared before me, James P. Pelletier, who, being duly sworn, did state that he is Vice President - Engineerin ofXermont Yankee Nuclear Power Corporation, that he is duly authorized to execute and file 50 the foregoing doc nt in app d on the behalf of Vermont Yankee Nuclear Power Corporation and that the 00 statements ther ahaco Mpe
's knowledge and belief.
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My Commission Expires February 10.1995 OSn.
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e VERMONT YANKEE NUCLEAR POWER STATION RESPONSE TO GENERIC LETTER 92 01 Question 1.
Certain addressees are requested to provide the following information regarding Appendix H to CFR Part 50:
Addressees who do not hava a surveillance program meeting ASTM E185-73, -79, or -82 and who do not have an integrated surveillance program approved by the NRC (see Enclosure 2), are requested to describe actions taken or to be taken to ensure compilance with Appendix H to 10CFR Part 50. Addressees who plan to revise the surveillance program to meet Appendix H to 10CFR 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 10CFR Part 50, addressees are requested to indicats when they plan to request an exemption from Appendix H to 10CFR Part 50 under 10CFR 50.60(b).
Response to Question 1.
The Vermont Yankee surveillance program meets the requirements of Appendix H to 10CFR Part 50. Appendix H requires that a reactor vessel have a surveillance program for the purpose of " monitor (ing) changes in the fracture toughness properties of ferritic materials in the reactor vessel beltline region." The Vermont Yankee surveillance capsulos comain the limiting beltline materials and we believe these surveillance capsules will be effective in monitoring neutron embrittlement throughout the licensed operating period.
The Vermont Yankee surveillance program complies with ASTM E185-66, which was the current version of the standard when the vessel was constructed. NRC approval of the surveillance program is documented in Reference (j). The NRC stated that l
"(w)e conclude that this program will adequately monitor radiation-induced changes l
In material fracture toughness properties of the ferritic materials of the Vermont l
Yankee reactor vessel during its service life."
The NRC has previously reviewed the results of the testing done on specimens from the surveillance capsule removed in March 1983 [ References (d) and (e)). Most recently the results of the surveillance capsule data and Technical Specification pressure / temperature limits were app.oved by NRC in Reference (e). As part of that evaluation the staff used the fol!owing NRC regulations and guidance: Appendices G and H of 10CFR Part 50; the ASTM Standards and the ASME Code, which are referenced in Appendices G and H; 10CFR 50.36(c)(2); Regulatory Guide 1.99, Rev.
2; Standard Review Plan (SRP) Section 5.3.2; and Generic Letter 88-11. The NRC using the surveillance capsule data as a
- basis, concluded that the pressure / temperature limits conform to the requirements of Appendices G and H of 10CFR Part 50.
RESPONSE TO GENERIC LETTER 92-01 Page 2 The surveillance program is designed to the ASTM E185-66 version of the standard which was in place at the time the vessel was purchased.
The Varch 1983 surveillance capsule testing and reporting met the requirements of ASThi E185-82.
Therefore, Vermont Yankee believes we meet the requirements of Appendix H and thus, we have no need to revise our surveillance program nor to request exemptions from Appendix H.
Ouestion 2.
Certain addressees are requested to provide the following information regarding Appendix G to CFR Part 50.
Question 2.a.
Addressees of plants for whict 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.1.2 or C.2.2 in Regu'atory Guide 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 the plate or fo@g and are requested to describe the actions taken pursuant to Paragraphs IV.A.1 or V.C. of Appendix G to 10CFR Part 50.
Response to Question 2.a.
The subject upper shelf energies of the Vermont Yankee vessel beltline materials are not expected to be less than 50 ft-lb by the end of the licensed operating period. The requirements of Paragraphs IV.A.1 of Appendix G to 10CFR Part 50 are satisfied and therefore, no additional actions are required. The basis for this determination is discussed below.
There are four (4) plates in the beltline region. The surveillance plate material is from Plate 1-14, Heat Number No. 3017-2. This plate has the highest initial reference temperature of the beltline materials. The other three plate materials were compared for chemistry, Charpy impact energy, and initial reference temperature. From this comparison, it was determined that these plates have upper shelf energies that are equal to or exceed the upper shelf energy of the surveillance plate. The upper shelf energy of the beltline welds was determined from Charpy testing performed on a typical production beltline weld.
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RESPONSE TO GENERIC LETTER 92 01 Page 3 Paragraph IV.A.1 states "...Roactor vessel beltline materials must have Charpy upper shelf energy of no less than 75 ft Ib (102J) initially and must maintain upper shelf energy throughout the life of the vessel of no iess than 50 ft Ib (68J)..." The evaluation of the data for the beltline and surveillance materials demonstrate that the upper shelf-energies were greatar than 75 ft lb 1. 'llally [ References (g), (h) and (i)). The evaluation i
of results obtained from the first surveillance capsule (1983) [ Reference (f)] show that upper shelf energies are not predicted to fall below the 50 ft-Ib limit throughout the current license.
Regulatory Guide 1.99, Revision 2 correlations for prediction of drop in upper shelf energy are limited to a fluence range of 1x10 e /cm to 6x10"n/cm. The maximum i
2 n
fluence at the 1/4 thickness location in the vessel through 32 EFPYs for Vermont Yankee is estimated to be 1.7xiO"n/cm. Thus, in order to assess the future drop in 2
upper shelf energy for the beltline materials, Vermont Yankee extrapolated the curves to lower fluences. Using this technique and the guidance of Paragraph C.2.2 of l
Regulatory Guide 1.99 Rev. 2, the upper shelf energies of all beltline materials are predicted to remain well above 50 ft lbs through the end of the operating license.
Therefore Question 2.a. does not apply to Vermont Yankee.
Question 2.b.
l Addressees whose reactor vessels were constructed to an ASME Code aarlier than the Summer 1972 Addenda of the 1971 Edition are requested to describe the i
consideration given to the following material properties in their evaluations performed pursuant to 10CFR 50.61 and Paragraph Ill.A of 10CFR Part 50, Appendix G.
Response to Question 2.b.
10CFR 50.61 is not applicable to Vermont Yankee as this requirement is specific to Pressurized Water Reactors (PWRs). Thus, our responses are related to Paragraph Ill.A of 10CFR 50, Appendix G only.
Question 2.b.(1)
The results from all Charpy and drop weight tests for all unirradiated beltline materials, the unirradlated reference temperature for each beltline material, and the method of determining the unirradiated reference temperature from the Charpy and drop weight test.
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RESPONSE TO GENERIC LETTER 92-01
)
Page 4 Response to Question 2.b.(1)
The Vermont Yankee reactor vessel was designed and fabricated in accordance with the ASME Code Section lil,1965 Edition and Addenda to and including the Summer 1966 Addenda.
Supplemental unirradiated fracture toughness, Charpy and tensile testing was conducted in 1983 for the same materials that are in the surveillance program. Drop weight tests were conducted as part of the original fabrication requirements and were not included in the supplemental testing. The supplemental testing was performed to provide more accurate and updated information on the unirradiated properties of the base material, weld metal, and heat-affected zone material. The determination of-unirradiated reference temperatures used the results of this supplemental testing, as well as the results from original testing, and is equivalent to the fracture toughness requirements of Paragraph ill.A of 10CFR Part 50, Appendix G. The results of the supplemental testing were summarized in a 1985 letter to the NRC [ Reference (g)] as part of a Technical Specification amendment to revise the pressure temperature curves. The NRC staff reviewed this information and approved its use in Reference (d).
Question 2.b.(2)
The heat treatment received by all beltline and surveillance materials; Response to Question 2.b.(2) l The supplemental fracture toughness tests performed on the surveillance material and the specimens contained in the Vermont Yankee surveillance program were heat treated in the same manner as the beltline materials. Since the heat treatment of the surveillance Charpy specimens is equivalent to that received by the beltline materials, the effects, if any, of heat treatment are considered and requirements of Paragraph ill.A of 10CFR Part 50, Appendix G are satisfied.
Question 2.b.(3)
The heat number of each beltline plate or forging and the heat number of wire and flux lot number used to fabricate each beltline weld.
l RESPONSE TO GENERIC LETTER 92 01 Page5 Response to Question 2.b.(3)
The beltline plate heat numbers were considered in the 10CFR Part 50, Appendix G evaluation by comparing chemical contents and the initial reference temperatures using th9 original fabrication records and supplemental fracture toughness tests. Plate I 14 s.. owed the highest initial reference temperature and was used to establish the limiting plate material. No forgings were used in the beltline materials.
All beltline welds were fabricated with 8018NM wire containing no flux. The AWS designation for this weld is AWS E8018-G. Lot numbers and heat numbers for 8018NM weld wire used in the fabrication of the Vermont Yankee vessel are available but are not cross-referenced to specific beltline weld identifiers. By comparison of the chemical content of all the heats of weld wire, the surveillance weld was determined to be representative of welds using the heats. Material properties for welds and HAZ were derived from a typical production weld containing 8018NM.
Question 2.b.(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.
Response to Question 2.b.f4)
The surveillance plate material was made from beltline Plate 114, Heat No. C3017-2.
The heat number of the weld wire used in the surveillance materials is not available.
AE TM E185-66 required that " samples shall represent one heat of the base metal and one butt weld if a weld occurs in the irradiated region." The specification for the surveillance weld required that it be made using the same type of weld wire and welding process used to fabricate the beltline welds.
The Vermont Yankee surveillance program contains Charpy's and tensile specimens made from a typical production 8018NM weld having no flux.
The surveillance weld was determined to be representative of the beltline welds through comparison of the chemical content of all the heats of weld wire obtained from the vessel fabrication records. More importantly, the available surveillance weld data provides Vermont Yankee with all of the information needed to meet the objective of Appendix H to monitor toughness changes due to irradiation.
i
RESPONSE TO GENERIC LETTER 92-01 Page 6 The results from surveillance weld testing complies with the requirements of 10CFR 50, Appendix G, Paragraph Ill.A for the following reasons:
1.
Archive surveillance weld material has been tested, providing complete baseline Charpy curve and chemical composition data.
2.
Irradiated surveillance weld Charpy specimen test curves can be compared credibly with the baseline Charpy curve. The copper and nickel content are known and the fluence has been established from the dosimetry in the surveillance capsule. Therefore, the necessary information is available to compare the survelliance weld irradiation embrittlement with Regulatory Guide 1.99, Revision 2 predictions.
Ouestion 2.b.(5_1 The chemical composition, in particular the weight in percent of copper, nickel, phosphorous, and sulfur for each beltline and surveillance material.
Response to Questions 2.b.(5)
The chemistry for the beltline plate materials was obtained from the Certified Matsrlal Test Reports (CMTRs) supplied by Lukens Steel. Additional tests were performed on the surveillance plate [ Reference (i)], however, only Cu, NI, and P were measured since these are considered to be the most important elements for predicting embrittlement. The chemistry and the inillal reference temperature of the surveillance plate material are representative of the limiting plate material.
The weld material in the Vermont Yankee surveillance program was made from a typical production 8018NM weld containing no flux. The weld wire is not copper coated hence the copper is present as an impurity in trace amounts. The chemistry of this weld was measured in the unirradiated condition [ Reference (i)] and also in the irradiated condition [ Reference (f)]. The only elements tested wem Cu, Ni, and P.
From this data a reasonable upper bound copper content and nickel content was determined. Using these chemistry values to predict the reference temperatures por Regulatory Guide 1.99, Rev. 2 and also taking into account the reference temperatures determined from the first surveillance capsu!e, the plate material (C3017-2) is the limiting material in the reactor vessel beltline.
RESPONSE TO GENERIC LETTER 92 01 j
Page 7 o
4 Question 2.b.(6) 4 The heat number of the wire used for determining the weld metal composition if-different than Question 2.b.(3) above.
e i
Response to Question 2.b.(6)
Question 2.b.6 is discussed in the response to Question 2.b.5.
Question 3.
[
Addressees are requested to provide the following information regarding commitments -
made to respond to Generic Leher No. 88-11.
Response to Question 3.
4 In our response to Generic Letter 88-11 [ Reference k) we stated " Vermont Yankee has previously predicted the effect of neutron radiation on reactor vessel materials using-the methods described in Regulatory Guide 1.99, Revision 2, as required by Generic j
Letter No. 88-11. Because the analysis was reviewed and approved by the NRC in Amendment No. 93 [ Reference (d)) to the Vermont Yankee Technical Specifications, l
no further technical analysis or modifications of the P T limits contained in the Vermont Yankee Technical Specifications are necessary in order to continueLto _ satisfy the l
requirements of Section V of 10CFR 50, Appendix G..Accordingly,-Vermont Yankes proposes no further actions be taken to ensure compilance with the revised reg 't guidance provided In Generic Letter No. 8811 (emphasis added)."
Therefu...
i-Questions 3.a 3.b and 3.c are not applicable to Vermont Yankee as no commitments were made in response to Generic Letter No. 88-11.
Question 3.a.
I How the embrittlement effects of operating at an irradiation temperature (cold leg or<
recirculation suction _ temperature) below 525'F.:were considered. -In 'particular-i licensees are requested to describe consideration given to determining the effect of l
lower irradiation temperature on the reference temperature and on the Charpy upper shelf energy.
Response to Question 3.a.
See the above response to Question 3.
[
i 6
j
HESPONSE TO GENERIC LETTER 92 01 Page 8 l
l Question 3.b.
How their surveillance results on the ' predicted amount of ' embrittlement were l
considered.
Response to Question 3.b.
l See the above response to Question 3.
Question 3.c.
If a measured increase in reference temperature exceeds the mean plus two standard i
deviations predicted by Regulatory Guide 1.99, Revision 2, or _lf a measured decrease In Charpy upper shell energy exceeds the value predicted using the guidance in Paragraph C.1.2 in Regulatory 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 j
material as predicted for December 16,1991 and for the end of its current license.
Response to Question 3.c.
l See the above response to Question 3.
l 1
RESPONSE TO GENERIC LETTER 92 01 Page 9
References:
(a)
License No. DPR 28 (Docket No 50 271)
(b)
Letter, USNRC to All Holders of Operating Licenses or Construction Permits for Nuclear Power Plants, Generic Letter No. 92-01, Revision 1,
" Reactor Vessel Structural Integrity,10 CFR 50.54(f)," dated March 6, 1992 (c)
Letter, USNRC to All Licensees of Operating Reactors and Holders of Construction Permits, NVY 88-144, Generic Letter No. 8811, "NRC Position on Radiation Embrittlement of Reactor Vessel Materials," dated July 12,1988 (d)
Letter, USNRC to VYNPC, NVY 86-121, Amendment No. 93 to Facility Operating License No. DPR 28, dated June 24,1986 (e)
Letter, USNRC to VYNPC, NVY_90-077, Amendment No.120 to Facility Operating License No. DPR 28, dated April 17,1990 (f)
M. L. Lowry, et al., " Final Report on Examination, Testing, and Evaluation of Irradiated Pressure Vessel Survelliance Specimens from the Vermont Yankee Nuclear Power Station to Yankee Atomic Electric Company," BCL-585-84-3, Battelle-Columbus Laboratories, May 15,1984 (g)
- Letter, VYNPC to
- USNRC, FVY 85-46,
" Reactor Vessel Pressure / Temperature Curves," dated May 10,1985 (h)
Letter, VYNPC to USNRC, FVY 85-107, " Response to Request for Additional Information Concerning Vermont Yankee Proposed Change No.129 - Reactor Vessel Pressure Vessel Temperature Curves," dated November 21,1985 (i)
L.M. Lowry and M.P. Landow, " Testing of Unirradiated Pressure Vessel Surveillance Baseline Specimens for the Vermont Yankee Nuclear Generating Plant to Yankee Atomic Electric Company," BCL-585 84-1.
Battelle-Columbus Laboratories, dated March 21,1984 (j)
" Safety Evaluation by the Division of Reactor Licensing U.S. Atomic Energy Commission in the Matter of Vermont Yankee Nuclear Power Company / Station - Docket No. 50-271," dated June 1,1971 (k)
Letter, VYNPC to USNRC, FVY 88-94, Vermont Yankee Response to Generic Letter No. 88-11 1
1