This “Technical Evaluation Report on the Content of the U.S. Department of Energy’s Yucca Mountain License Application; Postclosure Volume: Repository Safety After Permanent Closure” (TER Postclosure Volume) presents information on the NRC staff’s review of DOE’s Safety Analysis Report (SAR), provided on June 3, 2008, as updated by DOE on February 19, 2009. The NRC staff also reviewed information DOE provided in response to NRC staff’s requests for additional information and other information that DOE provided related to the SAR.

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

Spent Fuel Project Office Interim Staff Guidance - 8

NRC/NEI, January 24, 2014 Public Meeting Presentations

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

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

NRC Waste Confidence Rulemaking, Federal Register, 1984, 1990, 1999, and 2008

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.

In the existing U.S. Environmental Protection Agency (EPA) and Nuclear Regulatory Commission (NRC) regulations governing the spent nuclear fuel and high-level radioactive waste site at Yucca Mountain, Nevada, the time period of compliance was set at 10,000 years. Recently, a Court ordered that EPA and NRC either revise the regulation on this topic to be "based upon and consistent with" recommendations made by a panel of the National Academy of Sciences, who recommended a time period of compliance out to as long as one million years, or seek congressional relief.

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).

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.

This paper provides a brief description of the United States Nuclear Regulatory Commission (NRC) and its regulatory process for the current nuclear fuel cycle for light water power reactors (LWRs). It focuses on the regulatory framework for the licensing of facilities in the fuel cycle. The first part of the paper provides an overview of the NRC and its regulatory program including a description of its organization, function, authority, and responsibilities.

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.

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

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

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

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