J. D. Lee

Bio: J. D. Lee is an academic researcher from Lawrence Livermore National Laboratory. The author has contributed to research in topics: Fusion power & Blanket. The author has an hindex of 14, co-authored 37 publications receiving 739 citations.

HYLIFE-II: A Molten-Salt Inertial Fusion Energy Power Plant Design — Final Report

Abstract: Enhanced safety and performance improvements have been made to the liquid-wall HYLIFE reactor, yielding the current HYLIFE-II conceptual design. Liquid lithium has been replaced with a neutronically thick array of flowing molten-salt jets (Li[sub 2]BeF[sub 4] or Flibe), which will not burn, has a low tritium solubility and inventory, and protects the chamber walls, giving a robust design with a 30-yr lifetime. The tritium inventory is 0.5 g in the molten salt and 140 g in the metal of the tube walls, where it is less easily released. The 5-MJ driver is a recirculating induction accelerator estimated to cost $570 million (direct costs). Heavy-ion targets yield 350 MJ, six times per second, to produce 940 MW of electrical power for a cost of 6.5 cents/kW[center dot]h. Both larger and smaller yields are possible with correspondingly lower and higher pulse rates. When scaled up to 1934 MW (electric), the plant design has a calculated cost of electricity of 4.5 cents/kW[center dot]h. The design did not take into account potential improved plant availability and lower operations and maintenance costs compared with conventional power plant experience, resulting from the liquid wall protection. Such improvements would directly lower the electricity cost figures. For example,more » if the availability can be raised from the conservatively assumed 75% to 85% and the annual cost of component replacement, operations, and maintenance can be reduced from 6% to 3% of direct cost, the cost of electricity would drop to 5.0 and 3.9 cents/kW[center dot]h for 1- and 2-GW (electric) cases. 50 refs., 15 figs., 3 tabs.« less

Atomic force microscopy of mammalian sperm chromatin

Abstract: We have used the atomic force microscope (AFM) to image the surfaces of intact bull, mouse and rat sperm chromatin and partially decondensed mouse sperm chromatin attached to coverglass. High resolution AFM imaging was performed in air and saline using uncoated, unfixed and unstained chromatin. Images of the surfaces of intact chromatin from all three species and of an AFM-dissected bull sperm nucleus have revealed that the DNA is organized into large nodular subunits, which vary in diameter between 50 and 100 nm. Other images of partially decondensed mouse sperm chromatin show that the nodules are arranged along thick fibers that loop out away from the nucleus upon decondensation. These fibers appear to stretch or unravel, generating narrow smooth fibers with thicknesses equivalent to a single DNA-protamine complex. High resolution AFM images of the nodular subunits suggest that they are discrete, clipsoid-shaped DNA packaging units possibly only one level of packaging above the protamine-DNA complex.

Waste Disposal Assessment of HYLIFE-II Structure

Abstract: Initial scoping analysis indicates that by using Type 304 stainless steel (SS), most of the vacuum vessel’s structural mass in the HYLIFE-II inertial fusion energy power plant conceptual design cou...

Recent Progress in Fusion-Fission Hybrid Reactor Design Studies

Abstract: An overview is presented for recent design trends and developments in fusion-fission hybrid reactor concepts. Emphasis is on recent progress and developments but a brief review of the evolution of the hybrid concept since 1950 is also presented. Required fusion performance and technology development issues for the fusion-fission hybrid are explored with the tandem mirror as the primary example of a fusion driver. The results show that fusion breeders, especially those with suppressed-fission blankets, have the potential to produce unprecedented quantities of fissile fuel. The resulting high light water reactor support ratio relaxes both the fusion performance required and the economic constraints for commercial feasibility. 75 refs.

Fission-suppressed blankets for fissile fuel breeding fusion reactors

Abstract: Two blanket concepts for deuterium-tritium (DT) fusion reactors are presented which maximize fissile fuel production while at the same time suppress fission reactions. By suppressing fission reactions, the reactor will be less hazardous, and therefore easier to design, develop, and license. A fusion breeder operating a given nuclear power level can produce much more fissile fuel by suppressing fission reactions. The two blankets described use beryllium for neutron multiplication. One blanket uses two separate circulating molten salts: one salt for tritium breeding and the other salt for U-233 breeding. The other uses separate solid forms of lithium and thorium for breeding and helium for cooling.

Effects of E×B velocity shear and magnetic shear on turbulence and transport in magnetic confinement devices

Abstract: One of the scientific success stories of fusion research over the past decade is the development of the ExB shear stabilization model to explain the formation of transport barriers in magnetic confinement devices. This model was originally developed to explain the transport barrier formed at the plasma edge in tokamaks after the L (low) to H (high) transition. This concept has the universality needed to explain the edge transport barriers seen in limiter and divertor tokamaks, stellarators, and mirror machines. More recently, this model has been applied to explain the further confinement improvement from H (high)-mode to VH (very high)-mode seen in some tokamaks, where the edge transport barrier becomes wider. Most recently, this paradigm has been applied to the core transport barriers formed in plasmas with negative or low magnetic shear in the plasma core. These examples of confinement improvement are of considerable physical interest; it is not often that a system self-organizes to a higher energy state with reduced turbulence and transport when an additional source of free energy is applied to it. The transport decrease that is associated with ExB velocity shear effects also has significant practical consequences for fusion research. The fundamental physics involved in transport reduction is the effect of ExB shear on the growth, radial extent and phase correlation of turbulent eddies in the plasma. The same fundamental transport reduction process can be operational in various portions of the plasma because there are a number ways to change the radial electric field Er. An important theme in this area is the synergistic effect of ExB velocity shear and magnetic shear. Although the ExB velocity shear appears to have an effect on broader classes of microturbulence, magnetic shear can mitigate some potentially harmful effects of ExB velocity shear and facilitate turbulence stabilization.

Protamines and male infertility.

Abstract: Protamines are the major nuclear sperm proteins. The human sperm nucleus contains two types of protamine: protamine 1 (P1) encoded by a single-copy gene and the family of protamine 2 (P2) proteins (P2, P3 and P4), all also encoded by a single gene that is transcribed and translated into a precursor protein. The protamines were discovered more than a century ago, but their function is not yet fully understood. In fact, different hypotheses have been proposed: condensation of the sperm nucleus into a compact hydrodynamic shape, protection of the genetic message delivered by the spermatozoa, involvement in the processes maintaining the integrity and repair of DNA during or after the nucleohistone-nucleoprotamine transition and involvement in the epigenetic imprinting of the spermatozoa. Protamines are also one of the most variable proteins found in nature, with data supporting a positive Darwinian selection. Changes in the expression of P1 and P2 protamines have been found to be associated with infertility in man. Mutations in the protamine genes have also been found in some infertile patients. Transgenic mice defective in the expression of protamines also present several structural defects in the sperm nucleus and have variable degrees of infertility. There is also evidence that altered levels of protamines may result in an increased susceptibility to injury in the spermatozoan DNA causing infertility or poor outcomes in assisted reproduction. The present work reviews the articles published to date on the relationship between protamines and infertility.

Abnormal spermatogenesis and reduced fertility in transition nuclear protein 1-deficient mice

Abstract: Transition nuclear proteins (TPs), the major proteins found in chromatin of condensing spermatids, are believed to be important for histone displacement and chromatin condensation during mammalian spermatogenesis. We generated mice lacking the major TP, TP1, by targeted deletion of the Tnp1 gene in mouse embryonic stem cells. Surprisingly, testis weights and sperm production were normal in the mutant mice, and only subtle abnormalities were observed in sperm morphology. Electron microscopy revealed large rod-like structures in the chromatin of mutant step 13 spermatids, in contrast to the fine chromatin fibrils observed in wild type. Steps 12–13 spermatid nuclei from the testis of Tnp1-null mice contained, in place of TP1, elevated levels of TP2 and some protamine 2 (P2) precursor. Most of the precursor was processed to mature P2, but high levels of incompletely processed forms remained in epididymal spermatozoa. Sperm motility was reduced severely, and ≈60% of Tnp1-null males were infertile. We concluded that TP1 is not essential for histone displacement or chromatin condensation. The absence of TP1 may partially be compensated for by TP2 and P2 precursor, but this dysregulation of nucleoprotein replacement results in an abnormal pattern of chromatin condensation and in reduced fertility.

HYLIFE-II: A Molten-Salt Inertial Fusion Energy Power Plant Design — Final Report

Abstract: Enhanced safety and performance improvements have been made to the liquid-wall HYLIFE reactor, yielding the current HYLIFE-II conceptual design. Liquid lithium has been replaced with a neutronically thick array of flowing molten-salt jets (Li[sub 2]BeF[sub 4] or Flibe), which will not burn, has a low tritium solubility and inventory, and protects the chamber walls, giving a robust design with a 30-yr lifetime. The tritium inventory is 0.5 g in the molten salt and 140 g in the metal of the tube walls, where it is less easily released. The 5-MJ driver is a recirculating induction accelerator estimated to cost $570 million (direct costs). Heavy-ion targets yield 350 MJ, six times per second, to produce 940 MW of electrical power for a cost of 6.5 cents/kW[center dot]h. Both larger and smaller yields are possible with correspondingly lower and higher pulse rates. When scaled up to 1934 MW (electric), the plant design has a calculated cost of electricity of 4.5 cents/kW[center dot]h. The design did not take into account potential improved plant availability and lower operations and maintenance costs compared with conventional power plant experience, resulting from the liquid wall protection. Such improvements would directly lower the electricity cost figures. For example,more » if the availability can be raised from the conservatively assumed 75% to 85% and the annual cost of component replacement, operations, and maintenance can be reduced from 6% to 3% of direct cost, the cost of electricity would drop to 5.0 and 3.9 cents/kW[center dot]h for 1- and 2-GW (electric) cases. 50 refs., 15 figs., 3 tabs.« less