Nuclear waste shipping container response to severe accident conditions, A brief critique of the modal study

The Modal Study (NUREG/CR-4829) attempts to upgrade the analysis of spent nuclear fuel transportation accidents, and to verify the validity of the present regulatory scheme of cask performance standards as a means to minimize risk. While an improvement over many prior efforts in this area (such as NUREG-0170), it unfortunately fails to create a realistic simulation either of a shipping cask, the severe conditions to which it could be subjected, or the potential damage to the spent fuel cargo during an accident. There are too many deficiencies in its analysis to allow acceptance of its results for the presumed cask design, and many pending changes in new containers, cargoes and shipping patterns will limit applicability of the Modal Study to future shipments. In essence, the Modal Study is a good start, but is too simplistic, incomplete, outdated and open to serious question to be used as the basis for any present-day environmental or risk assessment of spent fuel transportation. It needs to be redone, with peer review during its production and experimental verification of its assumptions, before it has any relevance to the shipments planned to Yucca Mountain. Finally, it must be expanded into a full risk assessment by inputing its radiological release fractions and probabilities into a valid dispersal simulation to properly determine the impact of its results. 51 refs

On the spectra of the quantized action-variables of the compactified Ruijsenaars-Schneider system

A simple derivation of the spectra of the action-variables of the quantized compactified Ruijsenaars-Schneider system is presented. The spectra are obtained by combining Kahler quantization with the identification of the classical action-variables as a standard toric moment map on the complex projective space. The result is consistent with the Schrodinger quantization of the system worked out previously by van Diejen and Vinet.Comment: Based on talk at the workshop CQIS-2011 (Protvino, Russia, January 2011), 12 page

Algebraic integrability of confluent Neumann system

In this paper we study the Neumann system, which describes the harmonic oscillator (of arbitrary dimension) constrained to the sphere. In particular we will consider the confluent case where two eigenvalues of the potential coincide, which implies that the system has S^{1} symmetry. We will prove complete algebraic integrability of confluent Neumann system and show that its flow can be linearized on the generalized Jacobian torus of some singular algebraic curve. The symplectic reduction of S^{1} action will be described and we will show that the general Rosochatius system is a symplectic quotient of the confluent Neumann system, where all the eigenvalues of the potential are double. This will give a new mechanical interpretation of the Rosochatius system.Comment: 17 pages, 1 figur

The quasi-bi-Hamiltonian formulation of the Lagrange top

Starting from the tri-Hamiltonian formulation of the Lagrange top in a six-dimensional phase space, we discuss the possible reductions of the Poisson tensors, the vector field and its Hamiltonian functions on a four-dimensional space. We show that the vector field of the Lagrange top possesses, on the reduced phase space, a quasi-bi-Hamiltonian formulation, which provides a set of separation variables for the corresponding Hamilton-Jacobi equation.Comment: 12 pages, no figures, LaTeX, to appear in J. Phys. A: Math. Gen. (March 2002

Self-duality of the compactified Ruijsenaars-Schneider system from quasi-Hamiltonian reduction

The Delzant theorem of symplectic topology is used to derive the completely integrable compactified Ruijsenaars-Schneider III(b) system from a quasi-Hamiltonian reduction of the internally fused double SU(n) x SU(n). In particular, the reduced spectral functions depending respectively on the first and second SU(n) factor of the double engender two toric moment maps on the III(b) phase space CP(n-1) that play the roles of action-variables and particle-positions. A suitable central extension of the SL(2,Z) mapping class group of the torus with one boundary component is shown to act on the quasi-Hamiltonian double by automorphisms and, upon reduction, the standard generator S of the mapping class group is proved to descend to the Ruijsenaars self-duality symplectomorphism that exchanges the toric moment maps. We give also two new presentations of this duality map: one as the composition of two Delzant symplectomorphisms and the other as the composition of three Dehn twist symplectomorphisms realized by Goldman twist flows. Through the well-known relation between quasi-Hamiltonian manifolds and moduli spaces, our results rigorously establish the validity of the interpretation [going back to Gorsky and Nekrasov] of the III(b) system in terms of flat SU(n) connections on the one-holed torus.Comment: Final version to appear in Nuclear Physics B, with simplified proof of Theorem 1, 56 page

Toward the feldspar alternative for cosmogenic 10Be applications

The possibility of quantifying surface processes in mafic or volcanic environment using the potentialities offered by the in situ-produced cosmogenic nuclides, and more specifically by the in situ-produced 10Be, is often hampered by the rarity of quartz minerals in the available lithologies. As an alternative to overcome this difficulty, we explore in this work the possibility of relying on feldspar minerals rather that on quartz to perform in situ-produced 10Be measurements in such environments. Our strategy was to cross-calibrate the total production rate of 10Be in feldspar (P10fsp) against the total production rate of 3He in pyroxene (P3px) by measuring 3He and 10Be in cogenetic pyroxene (3Hepx) and feldspar (10Befsp). The samples were collected from eight ignimbritic boulders, exposed from ca 120 to 600 ka at elevations ranging from 800 to 2500 m, along the preserved rock-avalanche deposits of the giant Caquilluco landslide (18°S, 70°W), Southern Peru. Along with data recently published by Blard et al. (2013a) at a close latitude (22°S) but higher elevation (ca. 4000 m), the samples yield a remarkably tight cluster of 3Hepx - 10Befsp total production ratios whose weighted-mean is 35.6 ± 0.5 (1s). The obtained weighted-mean 3Hepx - 10Befsp total production ratio combined with the local 3Hepy total production rate in the high tropical Andes published by Martin et al. (2017) allows to establish a total SLHL 10Be in situ-production rate in feldspar mineral (P10fsp) of 3.57 ± 0.21 at.g-1.yr-1 (scaled for the LSD scaling scheme, the ERA40 atm model and the VDM of Lifton, 2016). Despite the large elevation range covered by the whole dataset (800–4300 m), no significant variation of the 3Hepx - 10Befsp total production ratios in pyroxene and feldspar was evidenced. As an attempt to investigate the effect of the chemical composition of feldspar on the total 10Be production rate, major and trace element concentrations of the studied feldspar samples were analyzed. Unfortunately, giving the low compositional variability of our dataset, this issue is still pending

Uplift of the Bolivian orocline coastal areas based on geomorphologic evolution of marine terraces and abrasion surfaces: preliminary results

The southern Pacific coast morphology and especially the presence of marine surfaces gives information on the dynamics of Andean forearc evolution from the Neogene. Along most of the Southern Peru and Northern Chilean coasts, discontinuous uplifts are recorded by marine terraces and marine abrasion surfaces; they have thus, preserved a record of eustatic sea level changes and the uplift history of the coastal area in the Andean forearc. One approach to study the tectonic history of the Andean forearc is to identify its effects in marine sedimentation or erosion patterns along the coastal area. To investigate these processes, the Neogene marine formations are studied in various coastal sections either in southern Peru, at Chala (15°50'S) and Ilo (17°32'S-17°48'S), situated above a steep subduction segment and at San Juan de Marcona (15°20'S), situated above the southern part of the Nazca ridge; or in Chile, from Tongoy (30°15'S) to Los Vilos (31°55'S), situated above a flat subduction segment (Fig.1). We chose various sites from each branch of the Arica bend in order to sample possibly different time spans during the Neogene and different response of the continental plate to the subduction process. Various studies were already undertaken on such problems either in Peru or Chile but mainly leaded to the datation of the 5th isotopic stage. So, differential GPS and cosmogenic datations are pursued in order to propose robust ages on these sites and subtract the effects of eustatic sea-level changes from local curves, identifying tectonic uplifts

Singularities, Lax degeneracies and Maslov indices of the periodic Toda chain

The n-particle periodic Toda chain is a well known example of an integrable but nonseparable Hamiltonian system in R^{2n}. We show that Sigma_k, the k-fold singularities of the Toda chain, ie points where there exist k independent linear relations amongst the gradients of the integrals of motion, coincide with points where there are k (doubly) degenerate eigenvalues of representatives L and Lbar of the two inequivalent classes of Lax matrices (corresponding to degenerate periodic or antiperiodic solutions of the associated second-order difference equation). The singularities are shown to be nondegenerate, so that Sigma_k is a codimension-2k symplectic submanifold. Sigma_k is shown to be of elliptic type, and the frequencies of transverse oscillations under Hamiltonians which fix Sigma_k are computed in terms of spectral data of the Lax matrices. If mu(C) is the (even) Maslov index of a closed curve C in the regular component of R^{2n}, then (-1)^{\mu(C)/2} is given by the product of the holonomies (equal to +/- 1) of the even- (or odd-) indexed eigenvector bundles of L and Lmat.Comment: 25 pages; published versio

Source model of the 2007 M_w 8.0 Pisco, Peru earthquake: Implications for seismogenic behavior of subduction megathrusts

We use Interferometric Synthetic Aperture Radar, teleseismic body waves, tsunami waveforms recorded by tsunameters, field observations of coastal uplift, subsidence, and runup to develop and test a refined model of the spatiotemporal history of slip during the M_w 8.0 Pisco earthquake of 15 August 2007. Our preferred solution shows two distinct patches of high slip. One patch is located near the epicenter while another larger patch ruptured 60 km further south, at the latitude of the Paracas peninsula. Slip on the second patch started 60 s after slip initiated on the first patch. We observed a remarkable anticorrelation between the coseismic slip distribution and the aftershock distribution determined from the Peruvian seismic network. The proposed source model is compatible with regional runup measurements and open ocean tsunami records. From the latter data set, we identified the 12 min timing error of the tsunami forecast system as being due to a mislocation of the source, caused by the use of only one tsunameter located in a nonoptimal azimuth. The comparison of our source model with the tsunami observations validate that the rupture did not extend to the trench and confirms that the Pisco event is not a tsunami earthquake despite its low apparent rupture velocity (<1.5 km/s). We favor the interpretation that the earthquake consists of two subevents, each with a conventional rupture velocity (2–4 km/s). The delay between the two subevents might reflect the time for the second shock to nucleate or, alternatively, the time it took for afterslip to increase the stress level on the second asperity to a level necessary for static triggering. The source model predicts uplift offshore and subsidence on land with the pivot line following closely the coastline. This pattern is consistent with our observation of very small vertical displacement along the shoreline when we visited the epicentral area in the days following the event. This earthquake represents, to our knowledge, one of the best examples of a link between the geomorphology of the coastline and the pattern of surface deformation induced by large interplate ruptures

Toward the feldspar alternative for cosmogenic 10Be applications in mafic environment

In situ-produced 10Be is one of the most commonly used TCN in quantitative geomorphology due to the fact that its production rate is relatively well constrained in the ubiquitous quartz mineral whose integrity minimizes the possibility of contamination by meteoric 10Be. Easily decontaminated from meteoric 10Be, it is in addition reliably measured using the Accelerator Mass Spectrometry technique for which its detection limit is lower than 104 at.g-1. However, volcanic or mafic areas are generally quartz free, which hamper the routine use of 10Be. In the case of a quartz poor lithology, an alternative possibility is to rely on 10Be - feldspars. Two preliminary studies (Kober et al., 2005 and Blard et al., 2013a) already provided promising results, demonstrating that (1) the decontamination protocol classically applied to quartz (Brown et al., 1991) efficiently removes all the meteoric 10Be contamination from the feldspar grains and (2) the total production rate of 10Be in feldspar is 8 to 10 % lower than that in quartz. However, only two samples were analyzed in both studies. In order to better constrain the 10Be in situ-production rate within feldspars, the number of samples analyzed needs to be increased. In this study, we developed a new chemical protocol for the 10Be extraction from feldspar matrices, and to cross-calibrate the total 10Be in situ-production rate in feldspar (P10fsp) against the total 3He production rate in pyroxene (P3px). The cosmogenic 3He and 10Be concentrations were measured, respectively, in pyroxene and feldspar extracted from eight samples of ignimbrite boulders from a giant landslide located between 800 and 2500 m in the high central Andes of Southern Peru. This area is ideally located, since two studies have already determined the local total 3He production rate in pyroxene on the nearby Altiplano (Blard et al., 2013b; Delunel et al., 2016)