ML20204G720

Forwards Response to NRC 981230 RAI Re Util Implementation of ASME Code Case N560 at Vermont Yankee Nuclear Power Station

ML20204G720
Person / Time
Site:	Vermont Yankee
Issue date:	03/19/1999
From:	Leach D VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20204G725	List: ML20204G720 ML20204G737 ML20204G746
References
BVY-99-26, NUDOCS 9903260255
Download: ML20204G720 (6)

Text

..

VERMONT YANKEE l

( (g-NUCLEAR POWER CORPORATION 185 Old Ferry Road, Brattleboro, VT 05301 7002 (802) 257-5271 March 19,1999 BVY 99-26 U.S. Nuclear Regulatory Commission

]

ATTN: Document Control Desk Washington, DC 20555

References:

(a) Letter, USNRC to VYNPC, " Request for Information Concerning Use of Code l Case N560 - Vermont Yankee Nuclear Power Station," NVY 98-168, dated December 30,1998.

(b) Letter, USNRC to VYNPC, " Request to Use Code Case N560 as an Alternative to the Requirements of ASME Code Section XI, Table IWB-2500-1 at Vermont Yankee Nuclear Power Station," NVY 98-155, dated November 9,1998. l (c) Letter, VYNPC to USNRC, " Implementation of ASME Code Case N560 at i Vermont Yankee - Response to NRC Questions," BVY-97-137, dated October 23,1997.

Subject:

Vermont Yankee Nuclear Power Station License No. DPR-28 (Docket No. 50-271)

Response to Request for Information Concerning Use of Code Case N560 - Vermont Yankee Nuclear Power Station l In Reference (a) the NRC staff requested Vermont Yankee (VY) to provide additional information in response to questions outlined in the enclosure to that letter. Attachment 1 is a detailed written reply to the staffs request. Attachments 2 and 3 provide supporting information for Attachment 1.

We trust that the information provided will be satisfactory. However, should you have any questions on this matter, please contact Mr. Wayne M. Limberger at (802) 258-4237.

Sincerely,

'EE NUCL RPOWE CORPORATION VERh)ONT

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, g%6 thrsilegerf ~ v ~

Vice Pre 'dentcEngineering i

l Attachments cc: USNRC Region I Administrator 4 USNRC Resident Inspector- VYNPS ,\

USNRC Project Manager-VYNPS l Vermont Department of Public Service 9903260255 990319 ~

PDR ADOCK 05000271 P PDR _

l Docket No. 50-271 BVY 99-26 i

Attachment 1 3 Vermont Yankee Nuclear Power Station l Request for Information Concerning Use of Code Case N560 Detailed Response to December 30,1998 Request for Additional Information 4

~ . .

Attachment I / Page 1 of 2

- Response to December 30,1998 RAI Regarding Code Case N-560 '

Reference (a) requested VY to provide additional information relative to several stainless steel welds included within the Class 1 piping population which were identified in the enclosure to that letter and in Table IV-4-1 of Reference (c).

The list of welds for which the staff requested information is shown in Table 1, attached. These welds were included in the old Inservice Inspection (ISI) Program 25% inspection sample, but are not included

. in the Code Case N-560 inspection sample.

The information requested for each weld was as follows:

e identify welds as shop or field welded.

• For field welds, indicate the joint configuration.

• For field welds, indicate the pipe or fitting size.

• For field welds, indicate which stress improvement method was employed.

• For field welds treated with IHSI, identify the IHS1 vendor.

• For field welds treated with IHSI, identify the frequency range used for induction heating.

• For field welds treated with IHSI, provide a discussion of what coil configurations were used for the performance oflHSI on pipe to fitting welds.

The required information is provided in Table 1, with the following clarifications.

Regarding the last item, coil configuration is difficult to determine based on information retained in our archives. An example of an lHSI data sheet for weld RR-AS-1 is attached showing the extent of available information. This document, which is typical of all IHSI data sheets, provides a record of the actual coil identification number that was used for IHSI, the length of that coil, and the weld joint configuration. The IHSI field procedure, a portion of which is attached for information, provides minimal information relative to the actual IHSI coil configuration. Nutech Engineers, the company that performed IHSI at Vermont Yankee, may have considered this information proprietary. Nutech is no longer in business, it should be noted that because of a 1998 corrective update to the ISI Program weld database, several l welds that were originally identified on the RHR-32 line are actually on the RHR-33 line. The RHR-33 1 line is a carbon steel line. Consequently, welds RH32 II, RH32-12, and RH32-13 (identified in the i RAI) are actually. carbon steel welds RH33 ll, RH33-12, and RH33-13, respectively. Because the particular welds noted above are carbon steel, Vermont Yankee did not research whether those welds were field or shop welds. If the staff desires, we can provide this information.

There were several other corrections made during the 1998 corrective update which affected the ISI l database, and consequently to a very minor degree, the N-560 degradation assessment. These corrections were incorporated into the N-560 selection process. A corrected N-560 database can be made available for staff review.

I 4

Attachment 1/ Page 2 of 2 A clarification to VY's response to a previous Request for AdditionalInformation question should also be noted. In Reference (c), RAI number VI-5 requested written documentation of the impact on other

. inspection programs such as 1GSCC (Generic Letter 88-01). A portion of the response stated that "The specific technical basis for eliminating IGSCC as an applicable mechanism in the Vermont Yankee Recirculation, Core Spray, and RHR Systems is as follows:

. All stainless steel piping has been replaced with low carbon Type 316 stainless steel.

. For additional resistance, til large bore field welds have been treated with Induction Heating Stress laprovement (IHSI), and all small bore field welds were heat sink welded. All shop welds were solution annealed after welding..."

It is true that all stainless steel piping within the scope of Code Case N-560 has been replaced with low l carbon Type 316 or 304 stainless steel and all stainless steel-to-stainless steel welds are, therefore, '

considered to be Category A welds. The second bullet in the response excerpted above was based on the 1985-1986 pipe-replacement outage. This replacement included all of the Recirculation system, all of the stainless steel portions of the Residual Heat Removal (RHR) system, and the portion of the Class 1 Reactor Water Cleanup (RWCU) system that was susceptible to the IGSCC initiating environment.

However, there were two less extensive pipe replacements performed during earlier refueling outages.

The Class I stainless steel Core Spray (CS) piping was replaced in the late 1970's and a portion of the Class I stainless steel RWCU line was replaced in the early 1980's. Consequently, those two groups of welds were not subjected to the same weld stress improvement methods applied during the 1985-1986 replacemer.ts. This is reflected in the attached Table i for welds CS4A-F3A, CS4A-MFS, CS4B-F3 A, CS4B-Fi A, and CU18 F15. Water backed (heat-sink) welding was not commonly used at Vermont Yankee until the early 1980's; therefore, the CS welds, which were predominantly shop welds, did not receive this treatment but the RWCU weld CU18-F15, to the best of our knowledge, did. We have been unable to retrieve' the fabrication records for this weld in time for the present submittal. However, those individuals involved in the work recall using water-backed technique for this earlier RWCU piping replacement.

Attachment I / Table 1/ Page 1 of 2 IHSI CoH Con 6guradon Weld Stress

' Frequency Actu System Weld Con gura- Imp o ement Vendor Si y (Hz) (in)

CS CS4A- 8 SW Pipe to None N/A N/A N/A N/A  !

F3A Pen. 1 (Pipe)

CS4A- 8 FW Valve to None N/A N/A N/A N/A MF5 Pipe I CS4B- 8 SW Pipe to None N/A N/A N/A N/A F3A Pipe CS4B- 8 SW Elbow to None N/A N/A N/A N/A F1A Pipe RHR RH32-5 20 FW Eibow to IHSI Nutech 3000-3090 11 1/2 4935-60 Valve RH33-11 20 N/A Pipe to Line is Carbon Pipe Steel RH33-12 20 N/A Elbow to Line is Carbon Pipe Steel RH33-13 20 N/A Pipe to Line is Carbon Elbow Steel RH30-7 24 FW Valve to (HSI Nutech 2700-2820 15 1/2 4935-81 Elbow RH30-6 24 SW Bent Pipe Solution N/A N/A N/A N/A to Elbow annealed RH31-1 24 SW Elbow to Solution N/A N/A N/A N/A Tee annealed RECIRC RR-N2A-1 12 FW Bent Pipe IHSI Nutech 2700 8 C-11202 to Bent Pipe RR-N2C-1 12 FW Bent Pipe IHSI Nutech 2790 8 C-11096 to Reducing Cross RR-N2C-2 12 FW Bent Pipe IHSI Nutech 2880-2910 8 C-11111 to Safe-end RR-N2D-1 12 FW Bent Pipe IHSl Nutech 3000 8 8935-57 to Tee

a Attachment I / Table 1/ Page 2 of 2 IHSt CoH Con 6guradon Weld Stress System Weld P We Configura- Imp o ement Fr u" Vendor y nge Le g Coil ID (Hz) (in) 3 RECIRC RR-N2D- 12 FW Bent Pipe IHSI Nutech 2800-2910 8 4935-57 l 2 to Safe-end RR-RH- 22 FW Bent Pipe IHSI Nutech 3000-3150 11 4935-87 A-2 to Cross j RR-RH- 22 SW Bent Pipe Solution N/A N/A N/A N/A l B-1 to annealed

]

Reducing l Tee j RR-AS-1 28 FW Pipe to IHSI Nutech 2880 14 1/2 C-11125 Bent Pipe RR-AS-5 28 FW Pipe to IHSI Nutech 3000 11 C-11108 Valve j RR-AS-6 28 SW Pipe to Solution N/A N/A N/A N/A )

Elbow annealed i RR-AD-8 28 FW Pipe to IHSI Nutech 3000-3060 13 1/2 4935-85

("RR-AS- Pump 8" sic)

RR-BS-1 28 FW Pipe to IHSI Nutech 2850-2970 14.88 4935-88 Bent Pipe RR-AB-2 4 FW Bent Pipe Heat Sink N/A N/A N/A N/A to Sweepolet RR-AB-7 4 FW Bent Pipe Heat Sink N/A N/A N/A N/A to Sweepolet RR-AB-8 28 SW Oent Pipe Solution N/A N/A N/A N/A to annealed xyapolet l RWCU CU18-10 4 FW Pipe to Heat Sink N/A N/A N/A N/A Tee CU18-9 4 FW Pipe to Heat Sink N/A N/A N/A N/A Valve CU18-8 4 FW Pipe to Heat Sink N/A N/A N/A N/A Valve CU18-5 4 FW Pipe to Heat Sink N/A N/A N/A N/A Valve CU18- 4 FW Pipe to See Note N/A N/A N/A N/A F15 Elbow Below*

• Although Vermont Yankee began using water-backed (heat sink) welding during the 1980-81 timeframe, we have been unable to retrieve the fabrication records for this weld in time for the present submittal. Those individuals involved in the work recall using water-backed technique for this NGfCU piping replacement.