The purpose of this activity is to develop a representative “limiting” axial burnup profile for pressurized water reactors (PWRs), which would encompass the isotopic axial variations caused by different assembly irradiation histories, and produce conservative isotopics with respect to criticality. The effect that the low burnup regions near the ends of spent fuel have on system reactivity is termed the “end-effect”. This calculation will quantify the end-effects associated with Pressurized Water Reactor (PWR) fuel assemblies emplaced in a hypothetical 21 PWR waste package.

The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips.

The American Nuclear Society (ANS) appreciates the opportunity to comment on the draft Nuclear Waste Administration Act (NWAA). The ANS is a not-for-profit, international, scientific, and educational organization with nearly 12,000 members worldwide. The core purpose of ANS is to promote awareness and understanding of the application of nuclear science and technology. As an organization, it has published a number of position statements regarding the issue of spent fuel and radioactive waste.

The American Nuclear Society (ANS) supports the safe, controlled, licensed, and regulated interim
storage of used nuclear fuel (UNF) (irradiated, spent fuel from a nuclear power reactor) until disposition
can be determined and completed. ANS supports the U.S. Nuclear Regulatory Commission’s (NRC’s)
determination that “spent fuel generated in any reactor can be stored safely and without significant
environmental impacts for at least 30 years beyond the licensed life for operation.

The purpose of this activity is to develop a representative “limiting” axial burnup profile for pressurized water reactors (PWRs), which would encompass the isotopic axial variations caused by different assembly irradiation histories, and produce conservative isotopics with respect to

It is increasingly apparent that the United States will require a large expansion of nuclear power
generation capacity to meet its future baseload electricity needs while reducing greenhouse gas
emissions. As a result, Congress and the Administration must act to update U.S. nuclear fuel
cycle policy to address these realities. This will likely require a multifaceted approach involving
some combination of on-site/centralized dry cask interim storage, nuclear fuel recycling, and
emplacement of high-level wastes in long-term geological storage.

More than 45 million shipments of radioactive materials have taken place in the United States
over the last three decades, with a current rate of about three million per year. The majority of
these radioactive shipments consist of radiopharmaceuticals, luminous dials and indicators,
smoke detectors, contaminated clothing and equipment, and research and industrial sources.
Fewer than 3,500, or 0.01%, have been involved in any sort of accident, incident, or anything

This calculation compares results from criticality evaluations for a 21-assembly pressurized water reactor (PWR) waste package based on 12 axial burnup profile representations for commercial spent nuclear fuel (SNF) assemblies. The burnup profiles encompass the axial variations caused by different fuel assembly irradiation histories in a commercial PWR, including end effects, and the concomitant effect on reactivity in the waste package. The bounding axial burnup profiles in Table T of reference 6.3 are used for this analysis.

The American Nuclear Society (ANS) supports (1) the development and use of geological
repositories for disposal of high-level radioactive wastes and (2) expeditious processing of the
Yucca Mountain license application in an open, technically sound manner. Geological disposal
means placing the wastes hundreds of feet underground and far from the biosphere. The U.S.
Nuclear Regulatory Commission (NRC) is following a legislatively well-defined regulatory
process to evaluate the safety of the proposed Yucca Mountain Site to meet both the scientific

In 1999, the United States Nuclear Regulatory Commission (U.S. NRC) initiated a research program
to support the development of technical bases and guidance that would facilitate the implementation of burnup
credit into licensing activities for transport and dry cask storage. This paper reviews the following major areas of
investigation: (1) specification of axial burnup profiles, (2) assumption on cooling time, (3) allowance for
assemblies with fixed and removable neutron absorbers, (4) the need for a burnup margin for fuel with initial