Utilization of burnup credit in criticality safety analysis for long-term disposal of spent
nuclear fuel allows improved design efficiency and reduced cost due to the large mass of fissile
material that will be present in the repository. Burnup-credit calculations are based on depletion
calculations that provide a conservative estimate of spent fuel contents (in terms of criticality
potential), followed by criticality calculations to assess the value of the effective neutron

The Commission is charged with submitting a
draft report to the Secretary of Energy before
the end of July 2011. To aid the Commissioners
in fulfilling that responsibility, the Commission
staff has prepared this report to summarize what
the Commission has heard up to this point in
the process. It does not attempt to recount every
comment or opinion submitted to the Commission
thus far; rather, the aim here is to summarize
major themes from the extensive testimony and
public comment the Commission has received to

This report describes a novel approach developed at the Oak Ridge National Laboratory
(ORNL) for the estimation of the uncertainty in the prediction of the neutron multiplication factor
for spent nuclear fuel. This technique focuses on burnup credit, where credit is taken in criticality
safety analysis for the reduced reactivity of fuel irradiated in and discharged from a reactor.
Validation methods for burnup credit have attempted to separate the uncertainty associated with

Transport of the damaged core materials from the Unit 2 reactor of the Three
Mile Island Nuclear Power Station (TMI-2) to the Idaho National Engineering Laboratory
(INEL) for examination and storage presented many technical and institutional
challenges, including assessing the ability to transport the damaged core;
removing and packaging core debris in ways suitable for transport; developing a
transport package that could both meet Federal regulations and interface with the

As part of a larger program to study mixed-oxide fuel subject to high burnup, some UO2 samples were exposed and analyzed. This report discusses results from the analysis of a UO sample that was burned in a boiling-water reactor (BWR) to approximately 57 GWd/t. The sample

Thirty spent fuel samples obtained from boiling-water-reactor (BWR) fuel pins have been
modeled at Oak Ridge National Laboratory using the SAS2H sequence of the SCALE code system.
The SAS2H sequence uses transport methods combined with the depletion and decay capabilities
of the ORIGEN-S code to estimate the isotopic composition of fuel as a function of its burnup
history. Results of these calculations are compared with chemical assay measurements of spent fuel
inventories for each sample. Results show reasonable agreement between measured and predicted

The "Summary Report of Commercial Reactor Criticality Data for Crystal River Unit 3" contains the detailed information necessary to perform commercial reactor criticality (CRC) analyses for the Crystal River Unit 3 (CR3) reactor.

The United States currently has no place to dispose of the high-level radioactive waste
resulting from the production of the nuclear weapons and the operation of nuclear
electronic power plants. The only option under formal consideration at this time is to place
the waste in an underground geologic repository at Yucca Mountain in Nevada. However,
there is strong public debate about whether such a repository could protect humans from
the radioactive waste that will be dangerous for many thousands of years. This book

Five commercial reactor criticals (CRCs) for the LaSalle Unit 1 boiling-water reactor
have been analyzed using KENO V.a, the Monte Carlo criticality code of the SCALE 4 code
system. The irradiated fuel assembly isotopics for the criticality analyses were provided by the
Waste Package Design team at the Yucca Mountain Project in the United States, who performed
the depletion calculations using the SAS2H sequence of SCALE 4. The reactor critical
measurements involved two beginning-of-cycle and three middle-of-cycle configurations. The

Disposal of radioactive waste from nuclear weapons production and power generation has
caused public outcry and political consternation. Nuclear Wastes presents a critical review
of some waste management and disposal alternatives to the current national policy of
direct disposal of light water reactor spent fuel. The book offers clearcut conclusions for
what the nation should do today and what solutions should be explored for tomorrow.
The committee examines the currently used "once-through" fuel cycle versus different