ML20353A397

NRC Response to Public Comment Regarding Spent Fuel Canister Drop from 2019 Regcon

ML20353A397
Person / Time
Site:	Diablo Canyon, HI-STORM 100, Holtec
Issue date:	12/18/2020
From:	Office of Nuclear Material Safety and Safeguards
To:
References
Download: ML20353A397 (2)

Text

From 2019 REGCON Meeting Public Comment A spent fuel canister that drops over 11 inches has to be opened to inspect the contents according to the Holtecs specifications. And there is no way to do that.

NRC Response The 11-inch lift height restriction is applicable to the HI-STORM 100 (CoC 72-1014) system which is not used at SONGS or Diablo Canyon.

The Holtec system used at SONGS is the Holtec International UMAX (CoC 72-1040). The Technical Specifications for the UMAX system are in NRC ADAMS Accession No. ML16341B100. The UMAX system uses the MPCs approved in the Holtec HI-STORM FW (CoC 72-1032). The Technical Specifications for the HI-STORM FW Amendment 3 system are in NRC ADAMS Accession No. ML17214A042. Sections 5.2 of the UMAX and HISTORM FW Technical Specifications do not place a limit on the lift height of the TRANSFER CASK with a loaded multipurpose canister (MPC) as long as the lifting equipment, including the horizontal beam and lifting attachments of a cask transporter, is designed, fabricated, operated, tested, inspected, and maintained in accordance with the requirements of a single failure proof lifting system that prevents uncontrolled lowering of the load.

The cask transporter used in Diablo Canyon ISFSI operations is designed, fabricated, inspected, maintained, operated, and tested in accordance with the applicable guidelines of NUREG-0612 for a single failure proof lifting system that prevents uncontrolled lowering of the load. (Section 8.2.4 of the Diablo Canyon Independent Spent Fuel Storage Installation Final Safety Analysis Report Update, Revision 6, March 2016, Docket No. 72-26 NRC ADAMS Accession No. ML16082A204).

For the HI-STORM 100 System (CoC 72-1014) the 11-inch drop analysis was based on the result of a conservative calculation by Holtec International which is described in their Final Safety Analysis Report (FSAR) Section 3.A. Although the accident analysis in the HISTORM 100 FSAR summarized in FSAR Section 11.2.2 show that the HI-STORM 100 overpack, fuel and the multipurpose canister (MPC) will not be damaged by an accidental drop, Holtec did include corrective actions for such an event. These corrective actions include inspection of the Overpack and the MPC for damage. If structural damage to the MPC is observed, the MPC is returned to the facility (i.e., a spent fuel pool) and unloaded.

This is only a possibility during transfer of the loaded canister to the storage system. In that situation, the spent fuel pool would still be available. A publicly available version of the HISTORM 100 FSAR (Rev 4) is in NRC ADAMS under Accession No ML063240599.

The Holtec HI-STORM FW system (CoC 72-1032) FSAR contains procedures for unloading the MPC into a spent fuel pool in section 9.4 (NRC ADAMS Accession No. ML17179A444).

The procedure includes precautions are outlined to ensure personnel safety during the unloading operations, and to prevent the risk of MPC over pressurization and damage to the fuel assemblies. The procedure also addresses prevention of flammable gas concentrations as a result of the radiolysis of water. These procedures have been reviewed and approved by the NRC.

The Holtec UMAX system (72-1040) CoC Condition 8 addresses preoperational testing and training exercise that must be completed prior to the first use of the UMAX system. All systems approved for storage of spent fuel have a similar condition in their respective CoC. The purpose of this CoC Condition 8 is to assure that unloading could be performed if operational issues are encountered during MPC loading, drying and placement operations. NRC inspectors observed the preoperational testing conducted at SONGS with the Holtec UMAX system (NRC ADAMS Accession No. ML18200A400).

2