ML14346A010

Calculation 1098-8, Revision 3, Helium Leak Testing Vent and Siphon Ports for Leak Tight Nuhoms Dscs.

ML14346A010
Person / Time
Site:	Oconee, 07200040
Issue date:	04/02/2014
From:	AREVA, Transnuclear
To:	Office of Nuclear Material Safety and Safeguards
References
1098-8, Rev 3
Download: ML14346A010 (8)

Text

ENCLOSURE 4Calculation Number 1098-8, Revision 3,Helium Leak Testing Vent and Siphon Ports for Leak Tight NUHOMS DSCs(Non-Proprietary version)

E-40451Enclosure 4A Form 3.1-1 Calc. No.: 1098-8TRANSNUCLEAR Calculation Rev. No.: 3Title: Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMS@ Page: of" 5DSC's Project No.: 1098DCR No.: 1098-39Project Name:Project 1098, NUHOMS 61BT for Oyster Creek Nuclear Generating StationCalculation Title: Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMS DSC'sNumber of CDs attached:If original issue, 10CFR72.48 review required?El No (explain) r- Yes, SR No.1. This calculation is complete and ready for Independent reviewOriginators Signature (,y w0LDate: O2. This calculation has e n checked fo c sistency, completeness, andarithmetic correctness.Checker Signature Date:3. Calculation preparation and check complies with procedure' package is completePEsSintueDae w4PE's SignatureDate: 0//,P24 A Form 3.1-1 CaIc. No.: 1098-8TRANSNUCLEAR Calculation Rev. No.: 3Title: Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMSO Page: 2 ofDSC's1. Background and Purpose:The leak test limit in NUHOMS 61 BT Technical Specification 1.2.4a (Amendment 7 toCertificate of Compliance 1004) is lx1 0-7 reference cm3/second. The objective is to"demonstrate the top cover plate to be 'leak tight', as defined in ANSI N14.5-1997."In order to fulfill the requirements of the Technical Specification and of ANSI N-1 4.5, it isnecessary to correlate test conditions to the reference conditions. That is the purpose of thiscalculation.The Technical Specification applicability is to the "inner top cover plate seal weld." The ventand siphon port covers are not mentioned, but it is conservative to include them in the leaktesting as well. To do this, helium may be injected below the vent and siphon port covers("silver dollars") prior to welding. Testing has been performed to determine the amount ofhelium remaining after welding, using various injection techniques (ref 4).Because the gas under the silver dollars may be a mixture of air and helium, and may be atsubatmospheric pressure due to the gas heating up during welding, then cooling down by thetime of leak testing, the leak tight acceptance criterion of 10. reference cm3/s must beadjusted for these conditions. The silver dollars and the inner top cover plate weld are typicallyleak tested simultaneously via the test port on the outer top cover plate. In this case, the leaktest rate for the silver dollars will be the determining rate, because the helium behind the outertop cover plate weld (the helium in the canister) will be nearly 100% pure and aboveatmospheric pressure.The results of this calculation are equally applicable to any NUHOMS DSC requiring testing tothe 10-7 ref cm3/s leak tight standard.Proprietary information withheld pursuant to 10 CFR 2.3902.

References:

1) ANSI N1 4.5-1997, Leak Tests on Packages for Shipment2) NUHOMS FSAR, NUH-003 rev 63) NUHOMS Certificate of Compliance 72-1004, amendment 74) Transnuclear document E-1 9308, Test Report For Helium Entrainment In Siphon And VentCavity With Welded "Silver Dollars" A Form 3.1-1 Calc. No.: 1098-8TRANSNUCLEAR Calculation Rev. No.: 3Title: Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMS Page: 3 of 5DSC's3. AssumptionsProprietary information withheld pursuant to 10 CFR 2.390 14. MethodANSI N14.5 will be followed throughout.5. CalculationsProprietary information withheld pursuant to 10 CFR 2.390 1 A Form 3.1-1 Calc. No.: 1098-8TRANSNUCLEAR Calculation Rev. No.: 3Title: Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMSO Page: 4 of 5DSC'sProprietary information withheld pursuant to 10 CFR 2.390 A Form 3.1-1 CaIc. No.: 1098-8TRANSNUCLEAR Calculation Rev. No.: 3Title: Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMS@) Page: 5 of 5DSC'sProprietary information withheld pursuant to 10 CFR 2.390 16. ConclusionFor a helium injection technique whereby helium is injected under an unmodified silver dollarprior to the start of welding, a measured leak rate of 3.4x10-8 atm cc/s helium or less will satisfythe Technical Specification limit of 10-7 ref cm3/s.For helium injection techniques whereby helium is injected under a modified silver dollar afterthe root pass is nearly complete, a measured leak rate of 8.8xl 08 atm cc/s helium or less willsatisfy the Technical Specification limit of 10-7 ref cm3/s.

ENCLOSURE 524 PHB leakage rates E-40451Enclosure 5Listing of the input and output for the 24 PRB leakage ratesDisk ID No. System/ File Series Number(size) Discipline Component (topics) of Files(Enclosure 6 24PHBThermal Leakage Rate 001- 24PHB_Leakage- Directory(84.0 KB forThermal)24PHB_Leakage.xls(Proprietary -Trade Secret)Input and output for the 24PHB leakage rates.In the spreadsheet, the worksheet "Bounding"uses the conservative leakage rate determinedby Oconee using the conservative correctionfactor at 1050F.The worksheet "Std Leak" repeats thecomputations from Calculation 1098-08 Rev.3 tovalidate the formula in the excel spreadsheet.Page 1 of 1