ML21253A105

Proposed Alternative to the ASME Code, NG-4230 Tack Welds, Docket 72-1004, CoC 1004, for Recent Amendments

ML21253A105
Person / Time
Site:	07201004
Issue date:	09/10/2021
From:	Narayanan P Orano TN Americas, TN & Associates
To:	Document Control Desk, Office of Nuclear Material Safety and Safeguards
Shared Package
ML21253A104	List: ML21253A105
References
E-59397
Download: ML21253A105 (7)

Text

September 10, 2021 E-59397 Orano TN 7160 Riverwood Drive U. S. Nuclear Regulatory Commission Suite 200 Director of the Office of Nuclear Material Safety and Safeguards Columbia, MD 21046 Attn: Document Control Desk USA One W hite Flint North Tel: 410-910-6900 11555 Rockville Pike Fax: 434-260-8480 Rockville, MD 20852

Subject:

Proposed Alternative to the ASME Code, NG-4230 Tack W elds, Docket 72-1004, CoC 1004, for Recent Amendments In accordance with the identical provision cited for each Certificate of Compliance (CoC) No. 1004 amendment listed below, TN Americas LLC (TN) requests an alternative to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code Section III, Division 1, Article NG, Subsection NG-4000 for Visual Examination (VT) requirements of tack welds of the NUHOMS 61BTH Type 2 Dry Shielded Canister (DSC), R45 transition rails, for each of the cited amendments.

x Paragraph 4.2.4 of CoC 1004 Appendix A, NUHOMS System Generic Technical Specifications (TS), Renewed Amendment 13, Revision 1, as corrected x Paragraph 4.2.4 of CoC 1004 Appendix A, TS, Renewed Amendment 14 x Paragraph 4.2.4 of CoC 1004 Appendix A, TS, Renewed Amendment 15 x Condition II.1.d of CoC 1004, Renewed Amendment 16 x Condition II.1.d of CoC 1004, Renewed Amendment 17 The alternative is requested only for the weld joints of the R45 transition rails between parts 1 and 2 of updated final safety analysis report (UFSAR) Drawing NUH61BTH-2003-SAR, Revision 2. No other components of the basket assembly are included. An illustration of the weld joint locations is provided in Enclosure 2.

Background

CoC 1004 Amendments 13, 14, and 15 TS 4.2.2, and Amendment 16 and 17 CoC Condition II.1.b, each state that DSCs are designed fabricated, tested, and inspected to the maximum practical extent in accordance with ASME B&PV Code Section III, Division 1, Subsections NB, NF, and NG for Class 1 components and supports. The R45 transition rails of the 61BTH Type 2 basket are classified as NG components in Section T.2.5.1 of Appendix T to the 61BTH DSC Design Criteria of the CoC 1004 UFSAR, Revision 20.

Tacks welds are used during the fit-up and alignment of the welded components of the R45 transition rails. The use of tack welds is standard practice for keeping parts closely together while completing the first pass, or root pass, of a production weld.

Enclosures transmitted herein contain SUNSI. When separated from enclosures, this transmittal document is decontrolled.

E-59397 Document Control Desk Page 2 of 4

Paragraph NG-4231.1 states, Tack welds used to secure alignment shall either be removed completely, when they have served their purpose, or their stopping and starting ends shall be properly prepared by grinding or other suitable means so that they may be satisfactorily incorporated into the final weld. Tacks welds shall be made by qualified welders using qualified welding procedures. When tack welds are to become part of finished weld, they shall be visually examined in accordance with NG-5261 and defective tack welds shall be removed.

TN believes the intent of the cited paragraph is to ensure that the final welds do not contain defects in the root pass from defective tack welds made during fit-up and alignment. The use of a qualified inspector for identification of defective tack welds is a means for providing this assurance. TN believes that the welding process and equipment used for completing the final weld can be qualified to achieve an acceptable level of quality and safety, thereby eliminating the need for a qualified inspector to perform the visual examination (VT) of NG-4231.1.

Proposed Alternative Along with the option to full comply with NG-4231.1, if practicable, the proposed alternative option to Paragraph NG-4231.1 is as follows:

The VT examination required by NG-4231.1 may be omitted for the welds of R45 Transition Rails of the NUHOMS 61BTH Type 2 DSC when the following additional requirements are met:

1. The welder or weld supervisor shall check the tack welds for def ects and shall either remove or repair the defective tack welds in the process of fit-up and alignment.

2. The welding procedure specification (W PS) and procedure qualification record (PQR) of the production welds shall contain the following additional qualification requirements for each joint geometry:

A. Three coupons shall be prepared that simulate the joint geometry that will be used in production. A tack weld shall be completed and broken.

B. The weld shall be completed with parameters that correspond to the minimum weld filler deposition rate allowed by the W PS.

C. The coupons shall be cross-sectioned, etched, and verified under magnification that the weld has satisfactorily incorporated the tack weld and the defect has been removed.

3. An additional PQR shall be prepared in accordance with ASME Section IX with coupons that were produced with three broken tack welds per coupon at fit-up.

The coupons shall pass all applicable testing requirements of ASME Section IX.

4. Production welds shall be made by either an automated welding or mechanized welding process. Only the tack weld may be completed by a manual process. shows how the alternative would appear in the form of the typical code alternatives table in the licensing basis.

Justification As previously stated, the intent of Paragraph NG-4231.1 is to provide reasonable assurance that defects in tack welds are not present in the final weld, which would reduce the effective throat available in the final weld. TN believes that additional controls in fabrication can be implemented that provide equivalent reasonable assurance that no defects from the tack weld are present in the final weld.

TN will have an individual qualified to perform or supervise the welding check for defective tack welds, and identified defective tack welds will be removed or repaired. The difference is that the E-59397 Document Control Desk Page 3 of 4

individual will not be a qualified inspector. This continues to ensure that defects in tack welds, such as a crack or complete fracture, are not present during completion of the final weld. This approach in allowing the welder or weld supervisor to check a tack weld for defects is in alignment with the requirements of Paragraph NB-4123, shown below.

In addition to the qualification requirements of ASME Section IX, the code alternative requires demonstration that production welding can re-consume a defective tack weld and obtain proper fusion in the root pass. The coupons will be welded with parameters that result in the lowest possible deposition rate allowed by the W PS. Verification by means of destructive testing that demonstrates the defect is removed and proper fusion is achieved will qualify the welding process. Use of a production weld to eliminate a defective tack weld is analogous to the provision of Paragraph NB-4423. Paragraph NB-4423 allows a fabricator to omit the back-gouging of defects and contaminants of a double welded joint through demonstration that the welding process can penetrate the defective area of the weld and obtain proper fusion.

The third requirement in the code alternative is an additional PQR of coupons that contain three broken tack welds at the time of fit-up. Destructively testing these coupons ensures the minimum mechanical properties are achieved even with the presence of broken tack welds.

The fourth requirement in the code alternative is to prohibit the use of manual welding for the completion of the production weld. By only using automated or mechanized welding equipment, the allowance for human error is effectively minimized, which will further ensure the root pass of the production weld is bound by the aforementioned qualification.

All other requirements of the ASME code for welding, welders, and filler metals, and the NDE required for the completed weld, remain unchanged.

The requirement for dimensional inspection of the completed R45 transition rail is required, regardless of a fabricator electing to use this code alternative. The R45 transition rail meeting its dimensional requirements of the design drawing assures that its primary design function, which is transfer of structural loads between the basket and shell, are maintained as described in the UFSAR for all normal, off-normal, and accident conditions. Secondary design functions of the R45 Transition Rails, such as thermal, criticality, and shielding, remain unaffected since geometrical attributes of the design drawing are verified and structural integrity of the welds are not affected by the proposed code alternative.

Conclusion In summary, along with the option to full comply with NG-4231.1, if practicable, TN is requesting an alternative to the ASME Paragraph NG-4231.1 requirement for tack welds of the R45 transition rails to be inspected by a qualified inspector. Compensatory measures are proposed including 1) verification that defective tack welds are either repaired or removed, performed by the welder or weld supervisor, 2) additional welding qualification requirements to ensure a E-59397 Document Control Desk Page 4 of 4

defective tack weld is repaired by the root pass of the production weld, 3) welding qualified is shown to achieve minimum mechanical even with broke tack welds, and 4) the welding equipment that can be used for the root pass is restricted to automated or mechanized. TN finds these compensatory measures acceptable to ensure the welds of the R45 transition welds provide an equivalent level of quality and safety. of this submittal includes proprietary information, which may not be used for any purpose other than to support NRC staff review of the proposed code alternative. In accordance with 10 CFR 2.390, I am providing an affidavit (Enclosure 1) specifically requesting that you withhold this proprietary information from public disclosure. Because Enclosure 2 is entirely proprietary, no public version is provided.

As previously discussed with NRC staff, NRC approval is respectfully requested as soon as practical to support on-going and future fabrication of the 61BTH Type 2 basket. If the NRC staff has any questions regarding this submittal, please do not hesitate to contact Mr. Doug Yates at 434-832-3101, or douglas.yates@orano.group.

Sincerely,

Prakash Narayanan Chief Technical Officer

cc: Christian Jacobs (NRC-DFM)

Affidavit Pursuant to 10 CFR 2.390 : Location of Applicable W eld Joints (Proprietary) : Proposed Code Alternative Table Entry

Enclosure I to E-59397

AFFIDAVIT PURSUANT TO 10 CFR 2.390

TN Americas LLC )

State of Maryland *, ) SS.

County of Baltimore )

I, Prakash Narayanan, depose and say that I am Chief Technica l Officer of TN Americas LLC, duly authorized to execute this affidavit, and have reviewed or caused to have reviewed the information that is identified as proprietary and referenced in the paragraph immediately below. I am submitting this affidavit in conformance with the provisions of 10 CFR 2.390 of the Commission ' s regulations for withholding this information.

The information for which proprietary treatment is sought meets the provisions of paragraph (a) (4) of Section 2.390 of the Commission's regulations. The information is contained in Enclosure 2, as listed below :

• Enclosure 2 -Location of Applicable Weld Joints (Proprietary)

I have personal knowledge of the criteria and procedure s utilized by TN Americas LLC in designating information as a trade secret, privileged or as confidential commercial or financial information. This document has been appropriately designated as proprietary.

Pursuant to the provisions of paragraph (b) ( 4) of Section 2.390 of the Commission ' s regu lations, the following is furnished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure, included in the above referenced document, should be withheld.

1) The information sought to be withheld from public disclosure involves portions of the updated final safety analysis report related to the design of the Standardized NUHOMS Dry Spent Fuel Storage System, which is owned by and has been held in confidence by TN Americas LLC.

2) The information is of a type customarily held in confidence by TN Americas LLC, and not customarily disclosed to the public. TN Americas LLC has a rational basis for determining the types of information customarily held in confidence by it.

3) Public disclosure of the information is likely to cause substantial harm to the competitive position of TN Americas LLC, because the information consists of descriptions of the design of dry spent fuel storage systems,

the application of which provide a competitive economic advantage. The availability of such information to competitors would enable them to modify their product to better compete with TN Americas LLC, take marketing or other actions to improve their product's position or impair the position of TN Americas LLC ' s product, and avoid developing similar data and analyses in support of their processes, methods or apparatus.

Further the deponent sayeth not.

Prakash Narayanan Chief Technical Officer, TN Americas LLC

Subscribed and sworn before me this q* th day of September 2021.

~ 1/4 ~ WQ ~

My Commission Expires QJ_; 30 I IO 2,3

Page 1 of I Enclosure 2 to E-59397

Location of Applicable Weld Joints (Proprietary)

Withheld Pursuant to 10 CFR 2.390 Enclosure 3 to E-59397

Proposed Code Alternative Table Entry

Reference ASME Code Code Requirement Alternatives, Justification and Compensatory Measures Section/Article NG-4231.1 Tack welds used to secure Along with the option to full comply with NG-4231.1, if alignment shall either be practicable, the proposed alternative option to Paragraph NG-removed completely, when 4231.1 is as follows:

they have served their purpose, or their stopping The VT examination required by NG-4231.1 may be omitted for and starting ends shall be the welds of R45 Transition Rails of the NUHOMS 61BTH properly prepared by Type 2 DSC when the following additional requirements are grinding or other suitable met:

means so that they may be satisfactorily 1. The welder or weld supervisor shall check the tack welds incorporated into the final for defects and shall either remove or repair the defective weld. Tacks welds shall tack welds in the process of fit -up and alignment.

be made by qualified 2. The welding procedure specification (WPS) and procedure welders using qualified qualification record (PQR) of the production welds shall welding procedures. contain the following additional qualification requirements When tack welds are to for each joint geometry:

become part of finished A. Three coupons shall be prepared that simulate the weld, they shall be visually joint geometry that will be used in production. A tack examined in accordance weld shall be completed and broken.

with NG-5261 and B. The weld shall be completed with parameters that defective tack welds shall result in the minimum weld filler deposition rate be removed allowed by the WPS.

C. The coupons shall be cross-sectioned, etched, and verified under magnification that the weld has satisfactorily incorporated the tack weld and the defect has been removed.

3. An additional PQR shall be prepared in accordance with ASME Section IX with coupons that were produced with three broken tack welds per coupon at fit-up. The coupons shall pass all applicable testing requirements of ASME Section IX.

4. Production welds shall be made by either an automated welding or mechanized welding process. Only the tack weld may be completed by a manual process.