Construction of Parseval wavelets from redundant filter systems

We consider wavelets in L^2(R^d) which have generalized multiresolutions. This means that the initial resolution subspace V_0 in L^2(R^d) is not singly generated. As a result, the representation of the integer lattice Z^d restricted to V_0 has a nontrivial multiplicity function. We show how the corresponding analysis and synthesis for these wavelets can be understood in terms of unitary-matrix-valued functions on a torus acting on a certain vector bundle. Specifically, we show how the wavelet functions on R^d can be constructed directly from the generalized wavelet filters.Comment: 34 pages, AMS-LaTeX ("amsproc" document class) v2 changes minor typos in Sections 1 and 4, v3 adds a number of references on GMRA theory and wavelet multiplicity analysis; v4 adds material on pages 2, 3, 5 and 10, and two more reference

Coronavirus disease 2019 (COVID-19) research agenda for healthcare epidemiology

This SHEA white paper identifies knowledge gaps and challenges in healthcare epidemiology research related to coronavirus disease 2019 (COVID-19) with a focus on core principles of healthcare epidemiology. These gaps, revealed during the worst phases of the COVID-19 pandemic, are described in 10 sections: epidemiology, outbreak investigation, surveillance, isolation precaution practices, personal protective equipment (PPE), environmental contamination and disinfection, drug and supply shortages, antimicrobial stewardship, healthcare personnel (HCP) occupational safety, and return to work policies. Each section highlights three critical healthcare epidemiology research questions with detailed description provided in supplementary materials. This research agenda calls for translational studies from laboratory-based basic science research to well-designed, large-scale studies and health outcomes research. Research gaps and challenges related to nursing homes and social disparities are included. Collaborations across various disciplines, expertise and across diverse geographic locations will be critical

Economics of at-reactor spent fuel storage alternatives

Estimates of costs that would be incurred by a utility providing enhanced storage capability for spent LWR fuel are presented. The cost data are arranged to assist in estimating and evaluating costs for specific storage situations. Estimated storage costs are provided in a series of tables providing cost factors or arrays for each alternative method of storage considered, and the additional costs involved in various options of pre-storage preparation of the fuel. Cost data are provided for (1) storage enhancement within an existing storage pool, by reracking and/or consolidation of fuel; (2) construction and use of an additional, separate water basin for storage; and (3) utilization of dry storage options. Costs are given for canning of integral assemblies and for consolidation and canning of fuel. In each case, the storage facilities are assumed to be located at an existing reactor site. If a separate site were to be utilized for storage, appropriate site development and maintenance costs would need to be added. The basic cost tables are tied togeter by a decision tree logic diagram designed to simulate the decision steps a utility planner might take in selecting from alternative storage technologies to best meet the requirements of his situation. Using the decision tree and its associated tables, example calculations were made to show the life cycle storage costs for a hypothetical case assuming a pressurized water reactor (PWR) site. The reactor was assumed to discharge 40 assemblies (18.4 MTU) of spent fuel each year; costs were estimated for storage periods of 1, 5, and 15 yrs, respectively. Discounted life cycle storage costs in thousands of dollars and unit costs in dollars per kilogram of initial uranium content are shown for this hypothetical site. Cost for spent fuel storage are dependent upon conditions at each reactor site and the most economical method is not expected to be the same at all sites

Evaluation of the commercial FBR introduction date

This report examines one criterion for introducing a commercial FBR: economic competitiveness with a Light Water Reactor (LWR). For this analysis, the commercial FBR is assumed to be the fifth-of-a kind replicate which represents an economically mature plant. This FBR is deemed economically competitive when its life-cycle energy cost is less than or equal to that of an LWR. Results of this analysis are used in a comparative analysis of alternative FBR development stategies. The strategies evaluated in these studies assume both 1000- and 1457-MWe FBRs. Since the capital costs per kilowatt, and therefore the energy costs, for these two FBR sizes are different, they will become economically competitive at different times. The probability density function for the 1457-MW(e) FBR has an expected value date or weighted average date of 2030, compared with 2033 for the probability density function for the 1000-MW(e) FBR

Long-term need for new generating capacity

Electricity demand should continue to grow at about the same rate as GNP, creating a need for large amounts of new generating capacity by the year 2000. Only coal and nuclear at this time have the abundant domestic resources and assured technology to meet this need. However, large increase in both coal and nuclear usage will not be acceptable to society without solutions to many of the problems that now deter their increased usage. For coal, the problems center around the safety and environmental impacts of increased coal mining and coal combustion. For nuclear the problems center around reactor safety, radioactive waste disposal, financial risk, and nuclear materials safeguards. The fuel requirements and waste generation for coal plants are orders of magnitude greater than for nuclear. Technology improvements and waste management practices must be pursued to mitigate environmental and safety impacts from electricity generation. 26 refs., 14 figs., 23 tabs

Potential growth of nuclear and coal electricity generation in the US

Electricity demand should continue to grow at about the same rate as GNP, creating a need for large amounts of new generating capacity over the next fifty years. Only coal and nuclear at this time have the abundant domestic resources and assured technology to meet this need. However, large increase in both coal and nuclear usage will require solutions to many of the problems that now deter their increased usage. For coal, the problems center around the safety and environmental impacts of increased coal mining and coal combustion. For nuclear, the problems center around reactor safety, radioactive waste disposal, financial risk, and nuclear materials safeguards. This report assesses the impacts associated with a range of projected growth rates in electricity demand over the next 50 years. The resource requirements and waste generation resulting from pursuing the coal and nuclear fuel options to meet the projected growth rates are estimated. The fuel requirements and waste generation for coal plants are orders of magnitude greater than for nuclear. Improvements in technology and waste management practices must be pursued to mitigate environmental and safety concerns about electricity generation from both options. 34 refs., 18 figs., 14 tabs

Analysis of the impact of retrievable spent fuel storage

The impact of retrievably storing spent fuel is measurable in terms of the contribution the stored spent fuel makes to implementing the fuel management option selected. For the case of a decision to recycle LWR fuel in LWRs, a useful indicator of impact is the ratio of energy production with varying degrees of spent fuel retrievability to that achievable with total spent fuel retrievability. For a decision made in the year 2000, this ratio varies from 0.81 (10 yr storage in reactor basins) to 0.97 (retrievable storage for 25 years after fuel discharge). An earlier decision to recycle in LWRs results in both of these ratios being nearer to 1.0. If a decision is reached to implement a breeder reactor economy, the chosen comparison is the installed breeder capacity achievable with varying degrees of spent fuel retrievability. If a decision to build breeder reactors is reached in the year 2000, the maximum possible installed breeder capacity in 2040 varies from 490 GWe (10 yr storage in reactor basins) to 660 GWe (all fuel retrievably stored). If all fuel is retrievably stored 25 years, 635 GWe of breeder capacity is achievable by 2040. For an earlier decision date, such as 1985, the maximum possible installed breeder capacity in 2040 ranges from 740 GWe (no retrievable storage) to 800 GWe (all fuel retrievably stored). As long as a decision to reprocess is reached before 2000, most of the potential benefit of retrievable storage may be realized by implementing retrievable storage after such a decision is made. Neither providing retrievable spent fuel storage prior to a decision to reprocess, nor designing such storage for more than 25 years of retrievability appear to offer significant incremental benefit

Analysis of thorium-salted fuels to improve uranium utilization in the once-through fuel cycle

Calculations and analyses indicate that no improvement can be achieved in uranium utilization for the once-through LWR fuel cycle over use of slightly enriched uranium by employing thorium distributed with uranium. The study included thorium additions: (1) slight amounts, (2) larger amounts, in either intimately mixed or in duplex pellets, (3) in spectrally shifted or not spectrally shifted reactors, and (4) in three- or five-year reactivity limited exposures. While thorium-uranium combinations improves the initial conversion ratio, the reactivity lifetime was not extended enough to override the additional uranium required. The effective fission cross-section of the bred /sup 233/U relative to /sup 239/Pu's in typical LWR neutron spectra is not large enough for /sup 233/U to make as great a contribution to end-of-life reactivity as /sup 239/Pu in a slightly enriched uranium fuel element. /sup 233/U's reactivity contribution relative to /sup 239/Pu's is lower in fuel configurations such as slightly enriched uranium LWR fuel loads. On the other hand, /sup 233/U's reactivity contribution appears more positive for reactors that involve lower average concentrations of thermal neutron absorbers. If /sup 238/U-thorium fuels reprocessed, the recovered /sup 233/U would increase uranium utilization, but may not reduce fuel cycle costs. The thorium-salted fuels exhibit substantially flatter reactivity characteristics with exposure time. Spectral shift helped the utilization of uranium and thorium

Sensitivity of the federal fee for managing spent fuel to financial and logistical variations

Three types of fees for federal spent fuel management service were calculated for a reference case and a number of variations. These fee types are a uniform fee applicable to all customers, a fee for disposal of spent fuel, and a fee for interim storage plus disposal of spent fuel. Results ranged from $124/kg to$256/kg for the uniform fee, $112/kg to$213/kg for the disposal fee, and $144/kg to$319/kg for the storage plus disposal fee. The reference case assumed that spent fuel would first be received by the government in 1983 at a 5,000 MT away-from-reactor (AFR) basin. The first repository (45,000 MT) was assumed ready for fuel in 1988, and the second (100,000 MT) in 1997. The reference case results in fees of $129/kg for the uniform fee,$117/kg for disposal, and $232/kg for storage plus disposal. The sensitivity cases were grouped in five general categories of variations from the reference case assumptions: demand for storage/disposal services, facility schedules and characteristics, methodology for calculating the fee, discount rate and AFR financing, and delays or failure of the first repository