Because there is currently no designated disposal site for used nuclear fuel in the United States, the nation faces the prospect of extended long‐term storage (i.e., >60 years) and deferred transportation of used fuel at operating and decommissioned nuclear power plant sites. Under U.S. federal regulations contained in Title 10 of the Code of Federal Regulations (CFR) 72.42, the initial license term for an Independent Spent Fuel Storage Installation (ISFSI) must not exceed 40 years from the date of issuance. Licenses may be renewed by the U.S.

About 20,000 metric tons of spent, or used, nuclear
fuel have accumulated since the beginning of commercial
nuclear power prbduction in the United States. At the end
of the currently licensed period of all existing nuclear power
plants and those under construction, the amount of spent
nuclear fuel is expected to total 87,000 metric tons.
Thus far, practically all of the spent nuclear fuel is
stored in water-filled pools at reactor sites. However, space
does not exist in the pools to store all the spent fuel expected

Taking credit for the reduced reactivity of spent nuclear fuel in criticality analyses is referred to
as burnup credit. Criticality safety evaluations employing burnup credit require validation of the
depletion and criticality calculation methods and computer codes with available measurement
data. To address the issues of burnup credit criticality validation, the U.S. Nuclear Regulatory
Commission initiated a project with Oak Ridge National Laboratory to (1) develop and establish

The Civilian Radioactive Waste Management System (CRWMS) Total System Model (TSM) is
a planning tool that estimates the logistic and cost impacts of various operational assumptions in
accepting radioactive wastes. Waste forms currently tracked are commercial spent nuclear fuel
(CSNF), Department of Energy (DOE) Spent Nuclear Fuel (DOE SNF), and High-Level
(radioactive) Waste (HLW). The TSM and associated programs analyze and simulate the actions
for waste acceptance from discharge until emplacement.

Direct disposal of the large canisters currently being used by the commercial nuclear power industry is beyond the current experience base domestically and internationally and potentially represents many other significant engineering and scientific challenges. Pragmatically, it is reasonable to assume that the packages that will be disposed of in the future may be significantly different from what is being used for storage today.

Presented at WM'03 Conference, Tucson, AZ, February 23-27, 2003

The purpose of this document is to provide the requirements rationale for the current version of the Preliminary Transportation, Aging and Disposal Canister System Performance Specification; WMO-TADCS-000001.

This report presents a formal analysis of the five sites nominated as
suitable for characterization for the first repository; the analysis is based
on the information contained or referenced in the environmental assessments
that accompany the site nominations (DOE, 1986a-e). It is intended to aid in
the site-recommendation decision by providing insights into the comparative
advantages and disadvantages of each site. Because no formal analysis can
account for all the factors important to a decision as complex as recommending

The validity of the computation of pressurized-water-reactor (PWR) spent fuel isotopic
composition by the SCALE system depletion analysis was assessed using data presented in the report.
Radiochemical measurements and SCALE/SAS2H computations of depleted fuel isotopics were
compared with 19 benchmark-problem samples from Calvert Cliffs Unit 1, H. B. Robinson Unit 2,
and Obrigheim PWRs. Even though not exhaustive in scope, the validation included comparison of
predicted and measured concentrations for 14 actinides and 37 fission and activation products.