ML20247E652

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Rev 0 to GE-NE-B13-01935-01, Jet Pump Riser Welds for RS-1 Indications Evaluation Rept for Vermont Yankee
ML20247E652
Person / Time
Site: Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date: 04/30/1998
From: Caine T, Herlekar A, Mallard L
GENERAL ELECTRIC CO.
To:
Shared Package
ML20247E613 List:
References
GE-NE-B13-01935, GE-NE-B13-01935-01, GE-NE-B13-1935, GE-NE-B13-1935-1, NUDOCS 9805180410
Download: ML20247E652 (5)
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Text

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Attachment 3 Vermont Yankee Nuclear Power Station Jet Pump Riser Circumferential Weld inspections End of Cycle Flaw Length and Leakage Rate Calculations l

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l-l May 1998 l

l 9905180410 990504 PDR ADOCK 05000271 P PDR  ;

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. GENxclurEnergy GE-NE-B13-01935-01 Rev. O DRF N B13-01935, Section 9 JET PUMP RISER WELD RS-1 INDICATIONS EVALUATION REPORT FOR VERMONT YANKEE April 1998 Prepared by: 4//d w 28 ff Lerond Mallard, Engineer Structural Mechanics & Materials Verified by: W d fh droon IIerlekar, Principal Engineer 1 Structural Mechanics & Materials  !

l l Reviewed by: A Tom A. Caine, Manager Structural Mechanics & Materials i

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GENxclextE ergy GE-NE-B13-Ol933-01 Rev. 0 DRF # B13-01933. Section 9 Executive Summary The leakage rates for jet pump riser indications found during the 1998 outage at Vermont Yankee were calculated for end of cycle, adjusted flaw lengths at normal operation and post-LOCA (Loss of Coolant Accident) condition riser to annulus pressure drops of 123 and 13 psid respectively.

Leakage in gpm at 100% flow Weld ID Adjusted Flaw Normal Operation LOCA Conditions Length 4.402" 21 7 N2B-RS-1 4.402" 21 7 N2C-RS-1 2.422" 12 4 N2H-RS-1 21 7  :

N2K-RS-1 4.402" ,

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, GENuclext Ezergy GE-NE-B13-01935-01 Rev. O

~ DRF N B13-01935, Section 9 l

1. Purpose -

l l The purpose of this report is to document the evaluation of the indications found at weld RS-1 forjet pump pairs 5 & 6; 9 & 10; 13 & 14; and 15 & 16 riser pipes during the 1998 outage for Vermont Yankee (Reference 1). The plant designation for the welds ofinterest are N2B-l RS-1, N2C-RS-1, N2H-RS-1, and N2K-RS-1.

l 2. Inputs and Methods The inputs for calculating the leakage rates for the indications found are listed below.

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1. Vermont Yankee riser differential pressure at normal' operating conditions as found in the plant specific database.
2. Vermont Yankee riser differential pressure for post-LOCA conditions as calculated in Reference 2.
3. Calculated IGSCC crack growth for eighteen months (12,000 hrs) cycle based on a growth rate of 5x10 4inch / hot hour.
4. Leakage rate is calculated based on adjusted flaw lengths at the end of one cycle for 1 normal operation and post-LOCA conditions.

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. GENuclear Energy GE-NE-BI3-01935-01 Rev. O DRF N BI3-01935. Section 9 i

3. Leakage Calculation -

Leakage from postulated through-wall flaws with length equal to the adjusted end of cycle flaw sizes are calculated based on the procedure described in section 5.1.1.5 of BWRVIP-41 (Reference 3). With riser AP values of 123 psid for normal operation and 13 psid for post-LOCA conditions, and a crack opening (S) conservatively assumed to be 10 mils, the leakage rates are tabulated below. For normal operations jet pump flow is assumed to be rated core flow. For post-LOCA conditions thejet pump riser flow is assumed to be the nominal LPCI flow rate used in the SAFER /GESTR analysis (Reference 5).

Leakage in gpm at 100% flow Weld ID Adjusted Flaw Normal Operation LOCA Conditions Length

  • Adjusted Flaw Length = observed indicatioa length + IGsCC growth + NDE uncertainty of 0382"(Reference 4).
4. References

[1] Letter from D. Yasi of Vermont Yankee Nuclear Power Corporation to J.P. Riley of GE, " Transmittal of JP Riser Indications Found during 1998 Inspection, dated April 10,1998.

[2] Jet Pump AP Calculation, Vermont Yankee Flaw Handbook, DRF # B13-01935, Section 9.

[3] BWRVIP-41, "BWR Jet Pump Assembly Inspection and Flaw Evaluation Guidelines," EPRI Report TR-108728, October 1997.

[4] Letter from Greg Selby of EPRI NDE Center to T. Hinkle of PECO Energy Corporation, " Review of Peach Bottom Jet Pump Riser VT and UT Inspections,"

dated October 28,1997.

[5] NEDC-32814P, Vermont Yankee Nuclear Power Station SAFER /GESTR-LOCA Loss-of-Coolant Accident Analysis, March 1998.

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