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

E-40451 Enclosure 4 A Form 3.1-1 Calc. No.: 1098-8 TRANSNUCLEAR Calculation Rev. No.: 3

Title:

Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMS@ Page: of" 5 DSC's Project No.: 1098 DCR No.: 1098-39 Project Name: Project 1098, NUHOMS 61BT for Oyster Creek Nuclear Generating Station Calculation

Title:

Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMS DSC's Number 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 review Originators Signature (,y w0LDate: O

2. This calculation has e n checked fo c sistency, completeness, and arithmetic correctness.

Checker Signature Date:

3. Calculation preparation and check complies with procedure' package is complete PE's Signature w4 PEsSintueDae Date: 0//,P24

A Form 3.1-1 CaIc. No.: 1098-8 TRANSNUCLEAR Calculation Rev. No.: 3

Title:

Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMSO Page: 2 of DSC's

1. Background and

Purpose:

The leak test limit in NUHOMS 61 BT Technical Specification 1.2.4a (Amendment 7 to Certificate of Compliance 1004) is lx1 0-7 reference cm 3/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 is necessary to correlate test conditions to the reference conditions. That is the purpose of this calculation.

The Technical Specification applicability is to the "inner top cover plate seal weld." The vent and siphon port covers are not mentioned, but it is conservative to include them in the leak testing 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 of helium 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 at subatmospheric pressure due to the gas heating up during welding, then cooling down by the time of leak testing, the leak tight acceptance criterion of 10. reference cm 3/s must be adjusted for these conditions. The silver dollars and the inner top cover plate weld are typically leak tested simultaneously via the test port on the outer top cover plate. In this case, the leak test rate for the silver dollars will be the determining rate, because the helium behind the outer top cover plate weld (the helium in the canister) will be nearly 100% pure and above atmospheric pressure.

The results of this calculation are equally applicable to any NUHOMS DSC requiring testing to the 10-7 ref cm 3/s leak tight standard.

Proprietary information withheld pursuant to 10 CFR 2.390

2.

References:

1) ANSI N1 4.5-1997, Leak Tests on Packages for Shipment

2) NUHOMS FSAR, NUH-003 rev 6

3) NUHOMS Certificate of Compliance 72-1004, amendment 7

4) Transnuclear document E-1 9308, Test Report For Helium Entrainment In Siphon And Vent Cavity With Welded "Silver Dollars"

A Form 3.1-1 Calc. No.: 1098-8 TRANSNUCLEAR Calculation Rev. No.: 3

Title:

Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMS Page: 3 of 5 DSC's

3. Assumptions Proprietary information withheld pursuant to 10 CFR 2.390 1

4. Method ANSI N14.5 will be followed throughout.

5. Calculations Proprietary information withheld pursuant to 10 CFR 2.390 1

A Form 3.1-1 Calc. No.: 1098-8 TRANSNUCLEAR Calculation Rev. No.: 3

Title:

Helium Leak Testing Vent & Siphon Ports for Leak Tight NUHOMSO Page: 4 of 5 DSC's Proprietary information withheld pursuant to 10 CFR 2.390

A Form 3.1-1 CaIc. No.: 1098-8 TRANSNUCLEAR Calculation Rev. No.: 3

Title:

Helium Leak Testing Vent &Siphon Ports for Leak Tight NUHOMS@) Page: 5 of 5 DSC's Proprietary information withheld pursuant to 10 CFR 2.390 1

6. Conclusion For a helium injection technique whereby helium is injected under an unmodified silver dollar prior to the start of welding, a measured leak rate of 3.4x10-8 atm cc/s helium or less will satisfy the Technical Specification limit of 10-7 ref cm 3/s.

For helium injection techniques whereby helium is injected under a modified silver dollar after the root pass is nearly complete, a measured leak rate of 8.8xl 08 atm cc/s helium or less will satisfy the Technical Specification limit of 10-7 ref cm 3/s.

ENCLOSURE 5 24 PHB leakage rates

E-40451 Enclosure 5 Listing of the input and output for the 24 PRB leakage rates Disk ID No. System/ File Series Number (size) Discipline Component (topics) of Files (Enclosure 6 24PHB Thermal Leakage Rate 001- 24PHB_Leakage- Directory (84.0 KB for Thermal) 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 determined by Oconee using the conservative correction factor at 105 0 F.

The worksheet "Std Leak" repeats the computations from Calculation 1098-08 Rev.3 to validate the formula in the excel spreadsheet.

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