ML20206L554

Safety Evaluation Approving Amend to Include as Authorized Activity,Storage of Moderated Special Nuclear Matl in sea-land Containers Equipped with Storage Grids Fastened to Floor

ML20206L554
Person / Time
Site:	Framatome ANP Richland
Issue date:	05/11/1999
From:	Emeigh C NRC
To:
Shared Package
ML20206L543	List: ML20206L537 ML20206L547 ML20206L554
References
NUDOCS 9905140058
Download: ML20206L554 (3)

Text

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UNITED #, FATES g* 4

,j' g NUCLEAR REGULATORY COMMISSION

'C WASHINGTON D.C. 20555-0001:

May 11, 1999 DOCKET: 70-1257 LICENSEE: Siemens Power Corporation (SPC)

Richland, Washington

SUBJECT:

SAFETY EVALUATION REPORT: STORAGE OF MODERATED SPECIAL -

NUCLEAR MATERIAL IN SEA-LAND CONTAINERS BACKGROUND j

By letter dated January 21,1999, the licensee requested an amendment to Materials License SNM-1227 to include, as an authorized activity, the storage of moderated special nuclear material (SNM) in sea-land containers equipped with storage grids fastened to the floor.

DISCUSSION SPC has in the past utilized sea-land containers for SNM storage, but in early 1998, SPC started utilizing a new facility, Operational Scrap Warehouse (Amendment 9), for the storage of unmoderated SNM in closed 5 gallon containers. At the time, this alleviated the need for the i sea-land containers. Since then, the NRC has approved the operation of two new recovery ,

facilities; the Modular Extraction Recovery Facility (Amendment 10) and the Liquid Uranium i

Recovery / Solids Processing Facility (Amendment 12). These facilities recover uranium compounds from the evaporation ponds and store waste that will require further processing i

through the solvent extraction process. The sea-land containers will provide the necessary capacity for the lag storage of this moderated SNM while it awaits solvent extraction.

CRITICALITY SAFETY SPC performed numerous KENO V.a calculations for both normal and abnormal scenarios using optimally moderated UO2 powder saturated with H2 0. The abnormal scenarios modeled were numerous and comprehensively analyzed the possible upset conditions. In each instance, the staff found that the models conservatively bounded the worst case abnormal condition and covered the credible single-failure mechanisms. SPC's double contingency analysis is summarized below.

1. Mass: The mass allowed in each storage pailis limited to no more than 45% of a critical mass, which is 18.0 kilograms for this application. Although the maximum mass of SNM

< that could be placed in a storage pail is significantly higher (i.e., approximately 86 kg),

f the mass is controlled through administrative controls and is compared to the data stored in NIMS prior to being placed in a storage array._ Multiple failures of the mass control were modeled as abnormal conditions and found to be within the license k., limits in all instances.

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2. Volume is controlled by limiting the size of the containers that may be used to store moderated SNM within the sea-land containers. The storage pails most commonly used in SPC operations involving moderated SNM are nominal 4-gallon high-density polyethylene (HDPE), however, any other container may be used as long as it meets the prescribed pail dimensions. The pail size is limited to e diameter of 11.25 inches or less and a height of 13.25 inches or less.

3. Geometry: Although the geometry of the storage pails is limited, it is not a favorable geometry and is not used as a control parameter.

4. Moderation: All SNM is considered to be optimally moderated and is not used as a control parameter. The HDPE in the storage pail walls was also analyzed for, potential moderation effects and found to be an acceptable container material.

5. Density of the SNM is limited to 4.0 g/cc due to the UO2 being powdered, and is not used directly as a control parameter.

6. Interaction: The storage grids affixed to the sea-land containers are designed to maintain one foot spacing between storage pails. In addition, the orientation of the grids within the sea-land containers is six inches from both the sides and the end of each sea-land container, which maintains the one foot spacing of storage pail between adjacent sea-land containers. Numerous credible spacing violations within the storage array were analyzed as well as stacking violations and all cases found to be within the license limits.

7. Reflection was modeled as 30 cm of water both above and below for most cases with concrete substituted for the lower reflector in some of the extreme abnormal cases.

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8. Enrichment: Maximum enrichment is limited to 5.0 wt.% 235U. Lower enrichments were analyzed and found to be bounded by the enrichment limit (5%).

Based on this review, the staff has reasonable assurance that a sufficient margin of safety exists  ;

i to prevent a nuclear criticality during normal and abnormal operating conditions, FIRE PROTECTION  :

Sea-land containers are non-combustible and when closed have a limited oxygen supply. The SNM will be stored in closed buckets spaced out evenly on the floor. SPC will minimize the risk l

of fires by minimizing the transient combustibles within the sea-land containers. The staff has l concluded that this is adequate.

CATEGORICAL EXCLUSION in the information provided on January 21,1999, the staff determined that the proposed change does not adversely affect public health and safety of the environment and the amendment should be categorically excluded from the requirements to prepare a specific environmental

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=3 assessment. ' Therefore, in accordance with 10 CFR 51.22(c)(11), neither an environmental

' assessment nor an environment impact statement is warranted.

CONCLUSION The staff has determined that the proposed storage of moderated SNM in sea-land containers

. does not adversely affect the health and safety of the workers, public, or the environment and the amendment to Materials License SNM-1227 should be approved.

Region IV inspection staff has no objection to this proposed amendment.

PRINCIPAL CONTRIBUTORS Jeremy Smith Paul Lain O- N"/D o

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