The requirements of ANSI/ANS 8.1 specify that calculational methods for away-from-reactor
criticality safety analyses be validated against experimental measurements. If credit for the negative
reactivity of the depleted (or spent) fuel isotopics is desired, it is necessary to benchmark
computational methods against spent fuel critical configurations. This report summarizes a portion
of the ongoing effort to benchmark away-from-reactor criticality analysis methods using selected
critical configurations from commercial pressurized-water reactors.

This report proposes and documents a computational benchmark problem for the estimation of the additional reactivity margin available in spent nuclear fuel (SNF) from fission products and minor actinides in a burnupcredit storage/transport environment, relative to SNF compositions containing only the major actinides. The benchmark problemlconfiguration is a generic burnup credit cask designed to hold 32 pressurized water reactor (PWR) assemblies.

Reactor physics computer programs are important tools that will be-used to estimate mixed oxide
fuel (MOX) physics performance in support of weapons grade plutonium disposition in U.S. and
Russian Federation reactors. Many of the computer programs used today have not undergone
calculational comparisons to measured data obtained during reactor operation. Pin power, the
buildup of transuranics, and depletion of gadolinium measurements were conducted (under Electric
Power Research Institute sponsorship) on uranium and MOX pins irradiated in the Quad Cities-l

The Disposal Criticality Analysis Methodology Topical Report, YMP/TR-0004Q (DOE 1998b) described a risk-informed methodology for postclosure criticality analyses in the potential repository at Yucca Mountain, Nevada. Various models contained in the methodology were described and a process for validating these models was presented. The topical report also committed to following this process in validating the models used for License Application.

Every year, more than 300 million packages of hazardous material are shipped in the
United States (U.S.). Most of the hazardous material shipped – about 97 percent – is
flammable, explosive, corrosive or poisonous. About 1 percent – three million packages –
of the hazardous materials shipped annually contains radioactive material, most of them
from medical and industrial applications. [DOT 1998b]
Spent nuclear fuel comprises a very small fraction of the hazardous materials packages

Presented at the NEI Used Fuel Management Conference, St. Petersburg, FL, May 7-9, 2013

Dear Secretary Chu:
At the direction of the President, you charged the Blue Ribbon Commission on America’s
Nuclear Future with reviewing policies for managing the back end of the nuclear fuel
cycle and recommending a new plan. We thank you for choosing us to serve as Co-
Chairmen of the Commission and for selecting the talented and dedicated set of
Commissioners with whom we serve.
We have sought to ensure that our review is comprehensive, open and inclusive. The
Commission and its subcommittees have heard from hundreds of individuals and

The purpose of this calculation is to determine the required minimum burnup as a function of initial pressurized water reactor (PWR) assembly enrichment that would permit loading of fuel into the 21 PWR waste package (WP), as provided for in QAP-2-0 Activity Evaluation, Perform Criticality, Thermal, Structural, & Shielding Analyses (Reference 7.1).

This report has been prepared to qualitatively assess the amount of burnup credit (reactivity margin) provided by ISG-8 compared to that provided by the burnup credit methodology developed and currently applied in France. For the purposes of this study, the methods proposed in the DOE Topical Report have been applied to the ISG-8 framework since this methodology (or one similar to it) is likely to form the basis of initial cask licensing applications employing limited burnup credit in the United States.

The U.S. Nuclear Regulatory Commission's guidance on burnup credit for pressurized-water-reactor (PWR) spent nuclear fuel (SNF) recommends that analyses be based on a cooling time of five years. This recommendation eliminates assemblies with shorter cooling times from cask loading and limits the allowable credit for reactivity reduction associated with cooling time. This report examines reactivity behavior as a function of cooling time to assess the possibility of expanding the current cooling time recommendation for SNF storage and transportation.

Presented at the NEI Used Fuel Management Conference, St. Petersburg, FL, May 7-9, 2013

The purpose of this analysis report is to evaluate the features, events, and processes (FEPs) associated with criticality and document the screening decision for either inclusion or exclusion of criticality in the Total System Performance Assessment for License Application (TSPA-LA). The FEPs associated with criticality address scenarios that include initiators of sequences of events or processes that could lead to configurations that have potential for criticality in the repository.

Hydrogen-induced cracking is characterized by the decreased ductility and fracture toughness of a material due to the absorption of atomic hydrogen in the metal crystal lattice. Corrosion is the source of hydrogen generation. For the current design of the engineered barrier without backfill, hydrogen-induced cracking may be a concern because the titanium drip shield can be galvanically coupled to rock bolts (or wire mesh), which may fall onto the drip shield, thereby creating conditions for hydrogen production by electrochemical reaction.

Taking credit for the reduced reactivity of spent nuclear fuel (SNF) in criticality analyses is referred to as burnup credit (BUC). Criticality safety evaluations require validation of the computational methods with critical experiments that are as similar as possible to the safety analysis models, and for which the keff values are known. This poses a challenge for validation of BUC criticality analyses, as critical experiments with actinide and fission product (FP)

The purpose of this report is to evaluate the potential for penetration of the Alloy 22 (UNS N06022) waste package outer barrier by localized corrosion due to the deliquescence of soluble constituents in dust present on waste package surfaces. The results support a recommendation to exclude deliquescence-induced localized corrosion (pitting or crevice corrosion) of the outer barrier from the total system performance assessment for the license application (TSPA-LA).

The work reported here is an investigation of the sensitivity of component temperatures in a specific storage system, including fuel cladding temperatures, in response to modeling assumptions that differ from design-basis, including age-related changes that could degrade the thermal behavior of the system. Preliminary evaluations of representative horizontal and vertical storage systems at design basis conditions provides general insight into the expected behavior of storage systems over extended periods of time.

The purpose of these calculations is to characterize the criticality safety concerns for the storage of Fast Flux Test Facility (FFTF) nuclear fuel in a Department of Energy spent nuclear fuel (DOE SNF) canister in a co-disposal waste package. These results will be used to support the analysis that will be done to demonstrate concept viability related to use in the Monitored Geologic Repository (MGR) environment.

The purpose of this scientific analysis report, CSNF Loading Curve Sensitivity Analysis, is to establish the required minimum burnup as a function of initial enrichment for both pressurized water reactor (PWR) and boiling water reactor (BWR) commercial spent nuclear fuel (CSNF) that would allow permanent disposal of these waste forms in the geologic repository at Yucca Mountain. The relationship between the required minimum burnup and fuel assembly initial enrichment forms a loading curve.

There are more than 250 forms of U.S. Department of Energy (DOE)­owned spent nuclear fuel (SNF). Due to the variety of the spent nuclear fuel, the National Spent Nuclear Fuel Program (NSNFP) has designated nine representative fuel groups for disposal criticality analyses based on fuel matrix, primary fissile isotope, and enrichment. For each fuel group, a fuel type that represents the characteristics of all fuels in that group has been selected for detailed analysis.

There are more than 250 forms of U.S. Department of Energy (DOE)-owned spent nuclear fuel (SNF). Due to the variety of the spent nuclear fuel, the National Spent Nuclear Fuel Program (NSNFP) has designated nine representative fuel groups for disposal criticality analyses based on fuel matrix, primary fissile isotope, and enrichment. Fast Flux Test Facility (FFTF) fuel has been designated as the representative fuel for the mixed-oxide (MOX) fuel group which is a mixture of uranium and plutonium oxides.

The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments.

The purpose of this design analysis is to determine the accuracy of the SAS2H module of SCALE 4.3 in predicting isotopic concentrations of spent fuel assemblies. The objective is to develop a methodology for modeling assemblies similar to those evaluated within this analysis and to establish the consistency of SAS2H predictions. The results of this analysis may then be applied to future depletion calculations using SAS2H in which no measurements are available.

The U.S. Department of Energy’s (DOE) Office of Civilian Radioactive Waste Management (OCRWM) is responsible, under the Nuclear Waste Policy Act of 1982, for the transportation of spent nuclear fuel and high-level radioactive waste from point of origin to destination at a federal storage or disposal facility. Section 180(c), written into the Nuclear Waste Policy Act Amendments of 1987, requires OCRWM to prepare public safety officials along the routes for these shipments.

This new report from the National Research Council’s Nuclear and Radiation Studies Board (NRSB) and the Transportation Research Board reviews the risks and technical and societal concerns for the transport of spent nuclear fuel and high-level radioactive waste in the United States. Shipments are expected to increase as the U.S. Department of Energy opens a repository for spent fuel and high-level waste at Yucca Mountain, and the commercial nuclear industry considers constructing a facility in Utah for temporary storage of spent fuel from some of its nuclear waste plants.

Dear Representatives Upton and Shimkus,
At the direction of the President, the Secretary of Energy established the Blue Ribbon
Commission on America’s Nuclear Future and charged it with reviewing policies for
managing the back end of the nuclear fuel cycle. We are serving as the Co-Chairmen of
the Commission and have taken note of your recent comments about the Commission’s
work.
Your comments echo those we have heard from several members of Congress and from
people across the country who believe the United States should not abandon the