Spent Fuel Project Office Interim Staff Guidance - 8

Spent Fuel Project Office, Interim Staff Guidance - 8, Revision 1

Since the mid-1980s, a significant number of studies have been directed at understanding the phenomena and
parameters important to implementation of burnup credit in out-of-reactor applications involving pressurizedwater-
reactor (PWR) spent fuel. The efforts directed at burnup credit involving boiling-water-reactor (BWR)
spent fuel have been more limited. This paper reviews the knowledge and experience gained from work
performed in the United States and other countries in the study of burnup credit. Relevant physics and analysis

Recognizing that Idaho has a major strategic and economic interest in maintaining INL’s leadership role and in helping
the nuclear energy industry successfully meet these broader challenges, Idaho governor C.L. “Butch” Otter established
the Leadership in Nuclear Energy or “LINE” Commission in February 2012.

The Governor recognized that recent national developments in the nuclear energy sector will cause the State of Idaho to
face important choices in the future and that he needed to understand the best options available.

The objective of this siting study work is to support DOE in evaluating integrated advanced nuclear plant and ISFSI deployment options in the future. This study looks at several nuclear power plant growth scenarios that consider the locations of existing and planned commercial nuclear power plants integrated with the establishment of consolidated interim spent fuel storage installations (ISFSIs).

This research examines the practice of equating the reactivity of spent fuel to that of fresh fuel for the purpose of performing burnup credit criticality safety analyses for PWR spent fuel pool (SFP) storage conditions. The investigation consists of comparing kf estimates based on reactivity "equivalent" fresh fuel enrichment (REFFE) to kl estimates using the actual spent fuel isotopics.

The United States makes decisions regarding the domestic uses of nuclear energy and the nuclear fuel cycle primarily based economic considerations, domestic political constraints, and environmental impact concerns. Such factors influence U.S. foreign policy decisions as well, but foreign policy decisions are often more strongly determined by national security considerations, including concerns about nuclear weapons proliferation and nuclear terrorism.

The requirements of ANSI/ANS 8.1 specify that calculational methods for away-from-reactor
(AFR) 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 AFR criticality analysis methods using selected critical
configurations from commercial pressurized-water reactors (PWR).

To advance nuclear energy to meet future energy needs, ten countries—Argentina, Brazil, Canada, France, Japan, the Republic of Korea, the Republic of South Africa, Switzerland, the United Kingdom, and the United States—have agreed on a framework for international cooperation in research for a future generation of nuclear energy systems, known as Generation IV. The figure below gives an overview of the generations of nuclear energy systems. The first generation was advanced in the 1950s and 60s in the early prototype reactors.

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 isotopic composition of mixed-oxide fuel (fabricated with both uranium and plutonium
isotopes) discharged from reactors is of interest to the Fissile Material Disposition Program. The
validation of depletion codes used to predict isotopic compositions of MOX fuel, similar to studies
concerning uranium-only fueled reactors, thus, is very important. The EEI-Westinghouse Plutonium
Recycle Demonstration Program was conducted to examine the use of MOX fuel in the San Onofre

Spent Fuel Project Office, Interim Staff Guidance - 8, Revision 2 - Burnup Credit in the Criticality Safety Analyses of PWR Spent Fuel in Transport
and Storage Casks

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 critical
configurations from commercial pressurized-water reactors.

The almost limitless energy of the atom was first harnessed in the United States, as scientists proved the basic physics of nuclear fission in a rudimentary reactor built in the floor of a squash court at the University of Chicago in 1942, and then harnessed that proven energy source in the form of atomic weapons used to end World War II. Scientists who accomplished this feat moved quickly after World War II to harness that power for peaceful uses, focusing primarily on electricity generation for industry, commerce, and household use.

The purpose of this U.S. Department of Energy Nuclear Waste Fund Fee Adequacy Assessment
Report (Assessment) is to present an analysis of the adequacy of the fee being paid by nuclear
power utilities for the permanent disposal of their SNF and HLW by the United States
government.
This Assessment consists of six sections: Section 1 provides historical context and a comparison
to previous fee adequacy assessments; Section 2 describes the system, cost, income, and

The Interim Staff Guidance on burnup credit for pressurized water reactor (PWR) spent nuclear fuel (SNF), issued by the United States Nuclear Regulatory Commission's (U.S. NRC) Spent Fuel Project Office, recommends the use of analyses that provide an "adequate representation of the physics" and notes particular concern with the "need to consider the more reactive actinide compositions of fuels burned with fixed absorbers or with control rods fully or partly inserted." In the absence of readily available information on the extent of control rod (CR) usage in U.S.

Isotopic characterization of spent fuel via depletion and decay calculations is necessary for
determination of source terms for subsequent system analyses involving heat transfer, radiation
shielding, isotopic migration, etc. Unlike fresh fuel assumptions typically employed in the criticality
safety analysis of spent fuel configurations, burnup credit applications also rely on depletion and
decay calculations to predict the isotopic composition of spent fuel. These isotopics are used in

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 is to be taken for
the reduced reactivity of burned or spent fuel relative to its original "fresh" composition, it is
necessary to benchmark computational methods used in determining such reactivity worth against
spent fuel reactivity measurements. This report summarizes a portion of the ongoing effort to

Spent fuel transportation and storage cask designs based on a burnup credit approach must
consider issues that are not relevant in casks designed under a fresh-fuel loading assumption. For
example, the spent fuel composition must be adequately characterized and the criticality analysis
model can be complicated by the need to consider axial burnup variations. Parametric analyses are
needed to characterize the importance of fuel assembly and fuel cycle parameters on spent fuel

This document summarizes DOE’s commercial nuclear energy RD&D program based on a R&D roadmap and on DOE/NE’s budget request for fiscal year 2011. The roadmap is written at a high level and is mostly qualitative in terms of activities, milestones and decisions to be made and does not contain budget information. The fiscal year 2011 budget request contains more specific and detailed information on activities, milestones, decisions, and budgets but only for fiscal year 2011 and the two preceding fiscal years.

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 is to be taken for
the reduced reactivity of burned or spent fuel relative to its original $fresh# composition, it is
necessary to benchmark computational methods used in determining such reactivity worth against
spent fuel reactivity measurements. This report summarizes a portion of the ongoing effort to

There has been a substantial resurgence of interest in nuclear power in the United States
over the past few years. One consequence has been a rapid growth in the research
budget of DOE’s Office of Nuclear Energy (NE). In light of this growth, the Office of
Management and Budget included within the FY2006 budget request a study by the
National Academy of Sciences to review the NE research programs and recommend
priorities among those programs. The programs to be evaluated were: Nuclear Power

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.