ML18123A284
| ML18123A284 | |
| Person / Time | |
|---|---|
| Site: | 07201004 |
| Issue date: | 07/12/2018 |
| From: | Michael Layton Division of Spent Fuel Management |
| To: | Bondre J TN Americas LLC |
| Love E | |
| References | |
| EA-18-088 | |
| Download: ML18123A284 (6) | |
Text
July 12, 2018 EA-18-088 Mr. Jayant Bondre Vice President and Chief Technical Officer TN Americas LLC 7135 Minstrel Way, Suite 300 Columbia, MD 21045
SUBJECT:
EXERCISE OF ENFORCEMENT DISCRETION - TN AMERICAS LLC
Dear Mr. Bondre:
This refers to the U.S. Nuclear Regulatory Commissions (NRCs) in-office review and results of the inspection performed on July 19, 2017, concerning a change to the Updated Final Safety Analysis Report (UFSAR) for Certificate of Compliance (CoC) No. 1004, Amendment No. 13 that describes a modified Type 2 basket design within a 32PTH1 Dry Shielded Canister (DSC),
specifically, a 32PTH1 Type 2-W basket.
Based on the results of the review of records, telephone conversations held on April 18, and June 26, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML17125A218 and ML17180A156), TN Americas LLCs (TN) e-mail response dated April 20, 2017 (ADAMS Accession No. ML17125A236), 10 CFR 72.48 Evaluation No. LR 721004-1586, Revision 0, dated February 10, 2017 (ADAMS Accession No. ML17125A022), and an NRC inspection performed at your corporate office, the NRC has determined that a violation of NRC requirements occurred. Specifically, 72.146, Design control, (b) states, in part, that The design control measures must provide for verifying or checking the adequacy of design by methods such as design reviews, alternate or simplified calculational methods, or by a suitable testing program. Contrary to this, the addition of a new 32PTH1 Type 2-W (as described in the safety analysis reports (SAR) under Docket No. 72-1004) basket resulted in a design change described in the final safety analysis report that has not been approved by the NRC for the intended application. Specifically, based on the lack of proper validation and adequate quantification of conservatisms, uncertainties, and errors, the method of evaluation used to evaluate the cask system heat removal capability could not be validated by a suitable testing program in order to demonstrate that peak cladding temperature is not exceeded.
The violation is of concern because adequate heat removal capacity is needed to preserve fuel cladding integrity and reasonable assurance could not be demonstrated that the predicted peak cladding temperature (PCT) will not exceed 752°F as recommended in ISG-11, Revision 3, Cladding Considerations for the Transportation and Storage of Spent Fuel and Standard Review Plan NUREG-1536, Standard Review Plan for Dry Cask Storage Systems. Additional technical detail regarding the violation is provided in the Enclosure to this letter.
As described in the Enclosure, the NRC considers the significance of this violation to be low; however, the design basis for the NUHOMS 32PTH1, Type 2-W Cask System assumes protection
J. Bondre 2 against fuel cladding rupture. The NRC recognizes that the operation of DSCs have been limited to decay heat below 27.75kW, which is below allowable design basis heat load for the current NUHOMS 32PTH1, Type 2-W Cask System. In addition, TN has entered this situation into their corrective action program and has provided docketed information (ADAMS Accession Nos.
ML18044A658 and ML18044A659) that demonstrates compliance to Title 10 of the Code of Federal Regulations (10 CFR) 72.146. TNs short-term corrective actions consisted of limiting operations such that the operation of DSCs were limited to allowing only spent fuel with decay heat below 27.75kW, which was below allowable design basis heats loads at that time for the NUHOMS 32PTH1, Type 2-W Cask System. TNs long-term corrective actions included the performance of an independent calculation using a computational fluid dynamics (CFD) model based on ANSYS FLUENT and ASME V&V 20-2009 in which the quantitative results showed adequate PCT limit margin for the 32PTH1 Type 2-W DSC design stored in the HSM-H horizontal storage module. The staff recognizes that TNs calculation and thermal evaluation of the 32PTH1 Type 2-W DSC in HSM-H used a method of evaluation (MOE) that was different from that utilized in the UFSAR, and that the evaluation includes discussion on how these results relate to other DSC designs associated with this situation using a MOE reviewed by NRC under a different CoC (1042).
The violation was evaluated in accordance with the NRC Enforcement Policy and has been characterized at Severity Level IV. However, I have been authorized, after consultation with the Director, Office of Enforcement, to exercise enforcement discretion in this case in accordance with Section 3.5, Violations Involving Special Circumstances, of the Enforcement Policy and not cite the violation because of: (1) the operation of DSCs have been limited to decay heat below 27.75kW, which is below allowable design basis heat loads for the current NUHOMS 32PTH1, Type 2-W Cask System; (2) the performance of an independent thermal evaluation using a CFD model created in ANSYS FLUENT code (as compared to ANSYS finite element analysis code as required by UFSAR), in which the results demonstrated adequate PCT temperature limit margin; (3) the clarity of the requirement and associated guidance; (4) confusion regarding the applicability of the 2006 NRC approval of the analysis due to NRC subsequently removing a written limitation in the safety evaluation report leading TN to assume that the restriction was lifted; (5) the low safety significance of the violation; and (6) all the issues have been addressed, all corrective actions have been completed. The current Enforcement Policy is included on the NRCs Web site at http://www.nrc.gov/about-nrc/regulatory/enforcement/enforce-pol.html.
The NRC concludes the background information on the apparent violation is adequately addressed on the docket. If you contest this action or its significance, you must provide a response within 30 days of the date of this letter, with the basis for your denial and/or corrected information, to the NRC, ATTN.: Document Control Desk, Washington, D.C. 20555-0001, with a copy to the Director, Office of Enforcement, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.
In accordance with 10 CFR 2.390 of the NRCs Agency Rules of Practice and Procedure, a copy of this letter will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records component of NRCs ADAMS. ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html.
J. Bondre 3 If you have any questions, please contact Earl Love at (301) 415-7011 or by e-mail at Earl.Love@nrc.gov.
Sincerely,
/RA/
Michael C. Layton, Director Division of Spent Fuel Management Office of Nuclear Material Safety and Safeguards Docket No.: 72-1004
Enclosure:
Technical Detail Regarding Review of TN Americas LLC 10 CFR 72.48 Evaluation No. LR 721004-1586, Revision 0
ML18123A284 C = COVER E = COVER & ENCLOSURE N = NO COPY *via email OFC *DSFM DSFM DSFM DSFM NMSS NAME ELove WWheatley YDiaz-Sanabria MRahimi MBurgess DATE 05/03/2018 05/11/2018 05/22/2018 05/31/2018 06/05/2018 OFC DSFM OE/EB DSFM NAME AHsia TMarenchin MLayton DATE 06/14/2018 06/28/2018 07/12/2018 Technical Detail Regarding Review of TN Americas LLC (TN) 10 CFR 72.48 Evaluation No. LR721004-1586, Revision 0 Review Scope The NRC conducted an in-office review and performed an inspection on July 19, 2017, of TNs Evaluation No. LR721004-1586, Revision 0, dated February 10, 2017, and TNs UFSAR for CoC No. 1004, Amendment No. 13 that describes a modified Type 2 basket design (32PTH1 Type 2-W) within a 32PTH1 DSC. The purpose of the review and inspection was to evaluate the thermal performance of the new basket using a MOE, which consists in ANSYS finite element analysis (FEA) in order to determine whether TNs thermal analysis adequately demonstrated that the storage cask provides adequate heat removal capacity needed to preserve fuel cladding integrity.
Observations and Findings
==
Description:==
To evaluate the thermal performance of a new basket (32PTH1 Type 2-W), TN used a MOE in accordance with ANSYS FEA and first principle calculations. Using this MOE, the evaluation indicated PCT was below the design basis limit by 3°F under storage conditions and by 5°F under transfer conditions. The staff noted the MOE was validated based on comparison of predicted temperatures to thermal test, as previously reported (ADAMS Accession No. ML050680080) and that the comparison of the MOE predicted values with the results from the previous thermal test did not constitute an acceptable validation. Specifically, TNs report could not provide well-defined boundary conditions (i.e., the correct heat flux profile on the inner boundary of the DSC). Based on the lack of proper validation and adequate quantification of conservatisms, uncertainties, and errors, the MOE used to evaluate the cask heat removal capability could not be validated in order to demonstrate that the PCT does not exceed the recommended limit of 752°F, as predicted by TN in LR721004-1586. The referenced thermal test report (ADAMS Accession No. ML050680080) states that the main purpose of the test program conducted on the HSM-H design is to validate the thermal analysis methodology employed in the design basis analysis of the HSM-H, as documented in the SAR for NUHOMS-24PTH, Rev. 4, Amendment No. 8 to Standardized NUHOMS Horizontal Modular Storage System for Irradiated Nuclear Fuel, NUH-003, Docket No. 72-1004 and SAR for NUHOMS HD Horizontal Modular Storage System for Irradiated Nuclear Fuel, Rev. 0, Docket No. 72-1030.
For the reasons stated earlier, the staff does not have confidence that predicted PCTs documented for these designs would not exceed the recommended limit.
72.146, Design control, (b) requires, in part, that design control measures must provide for verifying or checking the adequacy of design by methods such as design reviews, alternate or simplified calculational methods, or by a suitable testing program. The addition of a new 32PTH1 Type 2-W basket resulted in a design change described in the UFSAR that has not been approved by the NRC for the intended application. Specifically, based on the lack of proper validation and adequate quantification of conservatisms, uncertainties, and errors, the method of evaluation used to evaluate the cask system heat removal capability could not be validated by a suitable testing program in order to demonstrate that peak cladding temperature is not exceeded. These issues also apply to the different canisters and storage modules under Docket Nos. 72-1004 and 72-1030.
Enclosure
Analysis:
The performance deficiency associated with this violation involved TNs failure to properly verify or check the adequacy of design control measures. This issue is considered to be of greater than minor significance since approximately 36 DSCs have been or will be loaded without proper validation that predicted PCTs documented for these designs would not exceed the recommended limit. The significance of this issue is considered to be low based on: (1) the operation of DSCs have been limited to decay heat below 27.75kW, which is below allowable design basis heats loads for the current NUHOMS 32PTH1, Type 2-W Cask System; and (2) the performance of an independent thermal evaluation using a CFD model created in ANSYS FLUENT code (as compared to ANSYS FEA code as required by the UFSAR) in which the results demonstrated adequate PCT temperature limit margin. TN has performed ANSYS FEA as required. No formal evaluation is required. TN entered this situation into their corrective action program, and completed an evaluation using ANSYS FEA code as required by the USFAR. As such, all the issues have been addressed and corrective actions have been completed.
Summary A Severity Level IV violation of 10 CFR 72.146, Design control, was identified for the implementation of a change to TNs UFSAR for CoC No. 1004, Amendment No. 13 that describes the addition of a modified Type 2 basket design (32PTH1 Type 2-W) within a 32PTH1 DSC.