Impact of alternative nuclear fuel cycle options on infrastructure and fuel requirements, actinide and waste inventories, and economics

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 222-223).The nuclear fuel once-through cycle (OTC) scheme currently practiced in the U.S. leads to accumulation of uranium, transuranic (TRU) and fission product inventories in the spent nuclear fuel. Various separation and recycling options can be envisioned in order to reduce these inventories while extracting additional energy and sending the ultimate waste to a repository. Choosing one of these options has direct implications for the infrastructure requirements, natural uranium consumption, actinide inventories in the system, waste repository needs and costs. In order to account for the complexity of the nuclear enterprise, a fuel cycle simulation code has been developed using system dynamics (CAFCA). An economic module was added using spreadsheets. Four main advanced fuel cycle schemes are assessed here within the context of the US market: 1) the twice-through cycle scheme (TTC): single-pass plutonium recycling in thermal spectrum LWRs using Mixed OXide (MOX) fuel; 2) Multi-recycling of TRU in sodium-cooled fast spectrum burner cores, characterized by a fissile conversion ratio lower than 1 (FBu); 3) Multi-recycling of TRU in sodium-cooled fast breeders with a conversion ratio of 1.23 (FBr); and 4) A two-tier scenario: a TTC scheme is practiced as a transition scheme to fast reactors. The base case scenario assumes annual nuclear energy demand growth rate of 2.5% from 2020 on. The technologies for plutonium separation as well as MOX fuel fabrication are assumed to be available in 2025 while the first commercial fast reactors, as well as the possibility to recycle their spent fuel, are assumed to be available in 2040.(cont.) For fast reactors, the cores are assumed to be TRU fueled, and the technology to separate the minor actinides is supposed to be available at the latest 5 years before deployment of fast reactors. Limits are applied on the building rate of reprocessing plants, which are also subject to a 80% minimum life-time loading factor requirement. It is found that, despite its higher cost, at the end of the century, the TTC scheme (single Pu-MOX recycle) does not lead to large improvements in terms of natural uranium consumption (16%), repository needs (considering both fission products and MA from reprocessing facilities, and spent MOX fuel) and TRU inventory reduction (although some shifting of TRU from storage to reactors occurs). This is especially significant because it is the only advanced fuel cycle option that can be deployed in large scale in the next few decades. However, if the primary reason for introduction of the more expensive fast reactors is resource enhancement and/or control of TRU in the nuclear waste, thermal reactor recycling allows the introduction of fast reactors to be delayed by 20-25 years. Moreover, once fast reactors are introduced, their deployment is accelerated compared to a 1-tier FR scenario. However, the two-tier scheme is the most expensive scheme as it combines the requirements of both the MOX technology and the FR technology. Sensitivity analyses were performed in order to assess the impact of secondary parameters. It is found that whatever the growth rate assumed, LWRs remain a significant part of the system at the end of the century, decades after fast breeders are introduced.(cont.) The reason is the fissile materials required for fabrication of start-up cores considerably affect the rate at which fast reactors can be deployed. As a result, the choice of the core design (compact core vs. large core) may be as significant as the choice of the conversion ratio. For example, the breeder scenario (CR=1.23) may lead to the same cumulative natural uranium consumption reduction (by 2100) as the self-sustaining reactors (CR=1.0) while leading to larger TRU inventory in the system and requiring greater fast reactor fuel reprocessing capacity. Allowing fast reactors to start with uranium only cores was not considered, as it will likely limit resource enhancement benefits of fast reactors. Still, in general, the higher the conversion ratio, the greater the fast reactor installed capacity, hence the greater the savings in natural uranium. Conversely, the best reduction in TRU from the OTC amount is obtained by the lower conversion ratio (45% for a pure burner with conversion ratio 0.0 by 2100). Doubling the minimum cooling time before reprocessing for all fuel types from 5 years to 10 years slows down the deployment of the fast reactors and therefore reduces their share in the total installed capacity. This is almost equivalent to replacing breeders with fast reactors with a conversion ratio of 0.75. Finally, the results show that starting the separation of the TRU 10 years prior to introduction of the fast reactors instead of 5 years provides a mid-term advantage (faster initial deployment) that vanishes within 25 years. In the long term, the fast reactor penetration results are insensitive to the assumed industrial capacity to build reprocessing facilities for the base case or at lower nuclear energy growth rates.(cont.) However, the assumed industrial capacity can be a real constraint if the nuclear energy growth rates are 4% or higher.by Laurent Guérin.S.M.S.M.in Technology and Polic

A comparative analysis of cultural value orientations of Polish and Turkish employees:implications for international human resource management

This study empirically compares and contrasts the cultural value orientations of employees from Poland and Turkey by testing the compatibility of their values in three stages through seven cultural dimensions. The first phase of the study deals with the assessment of inter-country cultural value differences; the second phase investigates the intra-country cultural dynamics between selected demographic groups; and the third phase examines the inter-country cultural differences among the selected demographic groups of employees. The research has been conducted adopting the Maznevski, DiStephano, and Nason's (1995) version of cultural perspectives questionnaire with a sample of 744 (548 Polish and 196 Turkish) respondents. The results show significant cultural differences between Poland and Turkey, a presence of cultural dynamics among certain demographic groups within the country, and a mixture of convergence and divergence in the value systems of certain demographic groups both within and between the two nation(s). The research findings convey important messages to international human resource strategists in order for them to employ an effective and rational employment policy and business negotiation approach(es) to effectively operate in these countries. It also highlights that diversity of cultural values not only requires viewing each of them through cultural dimensions at a macro-level with a cross-country reference, but also requires monitoring their dynamics at the micro-level with reference to controlled demographic groups

Diffusion of gold nanoclusters on graphite

We present a detailed molecular-dynamics study of the diffusion and coalescence of large (249-atom) gold clusters on graphite surfaces. The diffusivity of monoclusters is found to be comparable to that for single adatoms. Likewise, and even more important, cluster dimers are also found to diffuse at a rate which is comparable to that for adatoms and monoclusters. As a consequence, large islands formed by cluster aggregation are also expected to be mobile. Using kinetic Monte Carlo simulations, and assuming a proper scaling law for the dependence on size of the diffusivity of large clusters, we find that islands consisting of as many as 100 monoclusters should exhibit significant mobility. This result has profound implications for the morphology of cluster-assembled materials

2+1 gravity and Doubly Special Relativity

It is shown that gravity in 2+1 dimensions coupled to point particles provides a nontrivial example of Doubly Special Relativity (DSR). This result is obtained by interpretation of previous results in the field and by exhibiting an explicit transformation between the phase space algebra for one particle in 2+1 gravity found by Matschull and Welling and the corresponding DSR algebra. The identification of 2+1 gravity as a $DSR$ system answers a number of questions concerning the latter, and resolves the ambiguity of the basis of the algebra of observables. Based on this observation a heuristic argument is made that the algebra of symmetries of ultra high energy particle kinematics in 3+1 dimensions is described by some DSR theory.Comment: 8 pages Latex, no figures, typos correcte

Probing Lorentz and CPT violation with space-based experiments

Space-based experiments offer sensitivity to numerous unmeasured effects involving Lorentz and CPT violation. We provide a classification of clock sensitivities and present explicit expressions for time variations arising in such experiments from nonzero coefficients in the Lorentz- and CPT-violating Standard-Model Extension.Comment: 15 page

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the $\gamma p$ centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil

D* Production in Deep Inelastic Scattering at HERA

This paper presents measurements of D^{*\pm} production in deep inelastic scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel $D^{*+}\to (D^0 \to K^- \pi^+) \pi^+$ (+ c.c.) has been used in the study. The $e^+p$ cross section for inclusive D^{*\pm} production with $5<Q^2<100 GeV^2$ and $y<0.7$ is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region {$1.3<p_T(D^{*\pm})<9.0$ GeV and $| \eta(D^{*\pm}) |<1.5$}. Differential cross sections as functions of p_T(D^{*\pm}), $\eta(D^{*\pm}), W$ and $Q^2$ are compared with next-to-leading order QCD calculations based on the photon-gluon fusion production mechanism. After an extrapolation of the cross section to the full kinematic region in p_T(D^{*\pm}) and $\eta$(D^{*\pm}), the charm contribution $F_2^{c\bar{c}}(x,Q^2)$ to the proton structure function is determined for Bjorken $x$ between 2 $\cdot$ 10$^{-4}$ and 5 $\cdot$ 10$^{-3}$.Comment: 17 pages including 4 figure

Observation of Scaling Violations in Scaled Momentum Distributions at HERA

Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of $x$ and $Q^2$ using the ZEUS detector. The evolution of the scaled momentum, $x_p$, with $Q^2,$ in the range 10 to 1280 $GeV^2$, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of $Q^2$.Comment: 21 pages including 4 figures, to be published in Physics Letters B. Two references adde

The adolescent and young adult (AYA) horizon study: An AYA cancer survivorship cohort

Background: In the United States, >45,000 adolescent and young adult (AYA) women are diagnosed with cancer annually. Reproductive issues are critically important to AYA cancer survivors, but insufficient information is available to address their concerns. The AYA Horizon Study was initiated to contribute high-quality, contemporary evidence on reproductive outcomes for female cancer survivors in the United States. Methods: The study cohort includes women diagnosed with lymphoma, breast, melanoma, thyroid, or gynecologic cancer (the five most common cancers among women ages 15–39 years) at three study sites: the state of North Carolina and the Kaiser Permanente health systems in Northern and Southern California. Detailed information on cancer treatment, fertility procedures, and pregnancy (e.g., miscarriage, live birth) and birth (e.g., birth weight, gestational length) outcomes are leveraged from state cancer registries, health system databases and administrative insurance claims, national data on assisted reproductive technology procedures, vital records, and survey data. Results: We identified a cohort of 11,072 female AYA cancer survivors that includes >1,200 African American women, >1,400 Asian women, >1,600 Medicaid enrollees, and >2,500 Hispanic women using existing data sources. Active response to the survey component was low overall (N ¼ 1,679), and notably lower among minority groups compared with non-Hispanic white women. Conclusions: Passive data collection through linkage reduces participant burden and prevents systematic cohort attrition or potential selection biases that can occur with active participation requirements. Impact: The AYA Horizon study will inform survivorship planning as fertility and parenthood gain increasing recognition as key aspects of high-quality cancer care

Pharmacokinetics of morphine in encephalopathic neonates treated with therapeutic hypothermia

Objective Morphine is a commonly used drug in encephalopathic neonates treated with therapeutic hypothermia after perinatal asphyxia. Pharmacokinetics and optimal dosing of morphine in this population are largely unknown. The objective of this study was to describe pharmacokinetics of morphine and its metabolites morphine-3-glucuronide and morphine-6-glucuronide in encephalopathic neonates treated with therapeutic hypothermia and to develop pharmacokinetics based dosing guidelines for this population. Study design Term and near-term encephalopathic neonates treated with therapeutic hypothermia and receiving morphine were included in two multicenter cohort studies between 2008-2010 (SHIVER) and 2010-2014 (PharmaCool). Data were collected during hypothermia and rewarming, including blood samples for quantification of morphine and its metabolites. Parental informed consent was obtained for all participants. Results 244 patients (GA mean (sd) 39.8 (1.6) weeks, BW mean (sd) 3,428 (613) g, male 61.5%) were included. Morphine clearance was reduced under hypothermia (33.5 degrees C) by 6.89%/degrees C (95% CI 5.37%/degrees C-8.41%/degrees C, p<0.001) and metabolite clearance by 4.91%/degrees C (95% CI 3.53%/degrees C-6.22%/degrees C, p<0.001) compared to normothermia (36.5 degrees C). Simulations showed that a loading dose of 50 mu g/kg followed by continuous infusion of 5 mu g/kg/h resulted in morphine plasma concentrations in the desired range (between 10 and 40 mu g/L) during hypothermia. Conclusions Clearance of morphine and its metabolites in neonates is affected by therapeutic hypothermia. The regimen suggested by the simulations will be sufficient in the majority of patients. However, due to the large interpatient variability a higher dose might be necessary in individual patients to achieve the desired effect