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This paper describes the development of an Australian roadmap for the acquisition of nuclear propulsion for submarines and selected other vessels. This paper reports on the goals of the working gro...

As future U.S. National Aeronautics and Space Administration (NASA) missions aim for destinations farther out into the solar system, space nuclear propulsion (SNP), and in particular nuclear therma...

Significance There is now an intensifying international effort to develop robust propulsion systems for hypersonic and supersonic flight. Such a system would allow flight through our atmosphere at very high speeds and allow efficient entry and exit from planetary atmospheres. The possibility of basing such a system on detonations, the most powerful form of combustion, has the potential to provide higher thermodynamic efficiency, enhanced reliability, and reduced emissions. This work reports a significant step in attaining this goal: the discovery of an experimental configuration and flow conditions that generate a stabilized oblique detonation, a phenomenon that has the potential to revolutionize high-speed propulsion of the future., Future terrestrial and interplanetary travel will require high-speed flight and reentry in planetary atmospheres by way of robust, controllable means. This, in large part, hinges on having reliable propulsion systems for hypersonic and supersonic flight. Given the availability of fuels as propellants, we likely will rely on some form of chemical or nuclear propulsion, which means using various forms of exothermic reactions and therefore combustion waves. Such waves may be deflagrations, which are subsonic reaction waves, or detonations, which are ultrahigh-speed supersonic reaction waves. Detonations are an extremely efficient, highly energetic mode of reaction generally associated with intense blast explosions and supernovas. Detonation-based propulsion systems are now of considerable interest because of their potential use for greater propulsion power compared to deflagration-based systems. An understanding of the ignition, propagation, and stability of detonation waves is critical to harnessing their propulsive potential and depends on our ability to study them in a laboratory setting. Here we present a unique experimental configuration, a hypersonic high-enthalpy reaction facility that produces a detonation that is fixed in space, which is crucial for controlling and harnessing the reaction power. A standing oblique detonation wave, stabilized on a ramp, is created in a hypersonic flow of hydrogen and air. Flow diagnostics, such as high-speed shadowgraph and chemiluminescence imaging, show detonation initiation and stabilization and are corroborated through comparison to simulations. This breakthrough in experimental analysis allows for a possible pathway to develop and integrate ultra-high-speed detonation technology enabling hypersonic propulsion and advanced power systems.

This paper discusses Nuclear Fuels for Propulsion which then opens up an entirely new branch and application of nuclear fuels that improves conventional fuels used for interstellar space travel, which has future scope in aerospace.

This chapter reveals that nuclear energy can be utilized to supply power in specialized cases. First, nuclear-powered ships and submarines were the inspiration of today’s commercial pressurized water reactors. Second, reactors can be employed for the propulsion and powering of space vehicles. Besides reactors, radioisotopes have been placed into service for heating and electric power generation in both terrestrial and space borne platforms. Future extraterrestrial applications include power for interplanetary exploration and terraforming.

Nuclear power-driven ships are becoming progressively more popular in advancing ship technology. Nuclear ships use naval reactors, which have lower fuel costs and last for many years and have almost zero emissions. The working of a Nuclear Ship is derived from the simple nuclear fission reaction. One more important factor that has spurred on the continuous investigates of nuclear power generation within ships is the irregular cost of flammable fuels. The unfavorable effects of burnt fuel being dispelled into the sea are also a concerning factor for green and sea life activists. Nuclear power applications have been limited due to safety concerns, but the new war against global warming is perched to drive its progress. In a span of a few years, safety risks may be minimized and nuclear power for power generation, in medicine and aboard ships and even in cars—may be the norm. The paper focuses the analysis of design for a nuclear-powered ship and the subsequent safety analysis of that ship in comparison with its fossil fuel ship. The final result of this paper shows that a suitable naval reactor for developing nuclear powered ship, while being technically feasible, will alternative to a fossil fuel powered ship. Keywords : Fuel cost, naval reactor, nuclear propulsion and ship designs Cite this Article Juwel M.M.H., Khondoker M.R.H., Khan R.A.. Performance Analysis of a Naval Reactor for Nuclear Powered Ship. Journal of Nuclear Engineering & Technology . 2018; 8(1): 1–6p.

Nuclear thermal propulsion is an enabling technology for delivering large payloads to Mars, and ground testing of a nuclear thermal engine is an important part of the development. A critical issue ...

The U.S. Navy operates an impressive fleet of nuclear-powered submarines and aircraft carriers and has safely operated its nuclear fleet for more than 60 years, while steaming over 154 million miles. Rigorous training has been key to maintaining such an impressive record. The U.S. Naval Nuclear Propulsion Training Program develops, certifies, and delivers the nuclear-operator qualification training for enlisted and officer personnel operating its nuclear fleet. This training finishes at one of four nuclear-power training units (NPTUs), operates under a complex set of hard and soft constraints, varies depending on the type of student, and requires significant personnel and equipment resources. We developed and implemented a mixed-integer linear program (MILP) that prescribes how many students of each type to allocate to each NPTU at the start of each class (a group of students who train together) and how allocated students complete NPTU training. The use of MILP has improved student allocation by an estimated eight percent and led to significantly improved use of both NPTU personnel and equipment resources. In this paper, we describe this unique optimization application, the MILP formulation, its path to adoption, its user interface, and impacts from its development and use over the past three years.

With the continued use of unsafeguarded naval nuclear-propulsion programs in all nuclear-weapon states, the commissioning of an Indian nuclear submarine, and the potential investment in such programs by non-nuclear-weapon states including Brazil and South Korea, movement toward a regulatory regime for nuclear material in the naval sector has become imperative. Such a framework faces a recurring debate on adequately protecting sensitive military technology while delivering assurances that naval nuclear material is not diverted to nuclear-weapon programs. In this viewpoint, we examine various prospective mechanisms to regulate naval nuclear stocks and assess them in terms of their effectiveness and scope. Drawing on lessons from the drafting, negotiation, and implementation of the Model Additional Protocol, we recommend a safeguards regime for naval nuclear material via a protocol that supplements the existing global nuclear-governance system. This protocol provides a standardized yet flexible approach to naval nuclear-material safeguards across all states (whether nuclearweapon states, non-nuclear-weapon states, or outside the Treaty on the Non-Proliferation of Nuclear Weapons) to handle variations among naval nuclear fuel cycles and technologies.

Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR) is a leading candidate for near-term human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement) for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER), for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR) utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of 100 MWth and an electricity generation mode of 100 kWth, equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and thermohydraulics was carried out. The result indicates that the innovative design has great potential for high propellant efficiency and thrust-to-weight of engine ratio, compared with the existing NTR designs. However, the build-up of fission products in fuel has a significant impact on the bimodal operation of the moderated reactor such as xenon-induced dead time. This issue can be overcome by building in excess reactivity and control margin for the reactor design.

International shipping has a well established reputation as the most energy efficient mode of freight transport. However, treating shipping within the context of global environmental concerns has gained significant momentum over the last 10 years, particularly in relation to the generation of Green House Gases (GHG) and other contributions to air and water pollution. Shipping relies on fuel oil and this implies that understanding the potential of alternative non-carbon marine propulsion technologies is necessary as the industry moves forward with its longer term decarbonisation efforts. Without any intend to underestimate the potential environmental and economic benefits of renewable, natural gas or non-fossil (e.g. biofuels) energy resources, it would be only sensible to add on the nuclear engineering option as a possible alternative. As successful as traditional nuclear propulsion has been in the naval and ice breaker ship segments, one aspect of the industry that escaped attention in the commercial sector is the use of modern small and medium size reactor technology on-board ocean going vessels. This paper reviews past and recent work in the area of marine nuclear propulsion and for the purpose of demonstration outlines the technical considerations on the concept design of a Suezmax Tanker powered by the Gen4Energy 70MW Small Modular Reactor (SMR). It is shown that understanding the technical risks and implications of implementing modern nuclear technology is an essential first step in the long term process of developing knowledge and experience.

The article systematises submarines, which are presently in service, according to their propulsion types (both conventional and nuclear), power output, and submersion depth. Contemporary types of propulsion systems installed and used in submarines are discussed. Calculations were performed for the PWR type nuclear propulsion system and the supercritical turbine propulsion system (supercritical reactor cooled with light water). Preliminary designs of turbines have been worked out for these two variants, and the systems were compared with respect to cycle efficiency and turboset efficiency.

The National Aeronautics and Space Administration Glenn Research Center (GRC) has an extensive history in dynamic energy conversion dating back to the early 1960s. This legacy puts the GRC at the forefront of nuclear power systems using thermodynamic power cycles such as Stirling and Brayton. The advantages of dynamic energy conversion include high efficiency, long life, and scalability to high power. These attributes make Brayton and Stirling power cycles an ideal solution for nuclear energy conversion.

The status and the main results achieved by Project 242 are presented. Project 242 is a programme (funded by ASI—1999/2002 from an idea of Carlo Rubbia) that studied a new concept of space propulsion motor by using direct conversion of the kinetic energy of fission fragments into increasing of enthalpy of a propellant gas. Project 242 studied the application of this propulsion system to a manned mission to Mars. Preliminary results were very satisfactory and it has been observed that a propulsion system with these characteristics could make the mission feasible. Results for other unmanned missions to the outer solar system are also presented.

Fusion-based nuclear propulsion has the potential to enable fast interplanetary transportation. Due to the great distances between the planets of our solar system and the harmful radiation environment of interplanetary space, high specific impulse ( I sp ) propulsion in vehicles with high payload mass fractions must be developed to provide practical and safe vehicles for human space flight missions. The Z-Pinch dense plasma focus method is a Magneto-Inertial Fusion (MIF) approach that may potentially lead to a small, low cost fusion reactor/engine assembly [1] . Recent advancements in experimental and theoretical understanding of this concept suggest favorable scaling of fusion power output yield [2] . The magnetic field resulting from the large current compresses the plasma to fusion conditions, and this process can be pulsed over short timescales (10 −6 s). This type of plasma formation is widely used in the field of Nuclear Weapons Effects testing in the defense industry, as well as in fusion energy research. A Z-Pinch propulsion concept was designed for a vehicle based on a previous fusion vehicle study called “Human Outer Planet Exploration” (HOPE), which used Magnetized Target Fusion (MTF) [3] propulsion. The reference mission is the transport of crew and cargo to Mars and back, with a reusable vehicle. The analysis of the Z-Pinch MIF propulsion system concludes that a 40-fold increase of I sp over chemical propulsion is predicted. An I sp of 19,436 s and thrust of 3812 N s/pulse, along with nearly doubling the predicted payload mass fraction, warrants further development of enabling technologies.

In the post-shuttle era, space exploration is moving into a new regime. Commercial space flight is in development and is planned to take on much of the low earth orbit space flight missions. With the development of a heavy lift launch vehicle, the Space Launch, System, NASA has become focused on deep space exploration. Exploration into deep space has traditionally been done with robotic probes. More ambitious missions such as manned missions to asteroids and Mars will require significant technology development. Propulsion system performance is tied to the achievability of these missions and the requirements of other developing technologies that will be required. Nuclear thermal propulsion offers a significant improvement over chemical propulsion while still achieving high levels of thrust. Opportunities exist; however, to build upon what would be considered a standard nuclear thermal engine to attain improved performance, thus further enabling deep space missions. This paper discuss the modeling of a nuclear thermal system integrated with an arc jet to further augment performance. The performance predictions and systems impacts are discussed.

The paper introduces recent Russian nuclear electric propulsion (NEP) concept for space exploration. The concept advantages are listed along with future missions. The current development status for the two main enabling technologies is presented and the feasibility analysis of the up-to-date experience is performed. The main features of NEP concept are discussed. Revision of these features and available technologies demonstrates that the NEP concept is a logical continuation of the previous efforts by the former Soviet Union. Because no breakthrough technologies are needed for NEP development while the existing technologies only need to be adapted to the megawatt (MW) class NEP the development is considered technically feasible, low risk program likely to succeed unless cancelled by the listed non-technical reasons. Successful NEP space vehicle development is going to bring practical space exploration of solar system to the new level as well as require supplementary payload program, supporting monitoring and communication radar networks. Nuclear safety during future NEP missions can be ensured by adherence to the United Nations guidelines in the same way it was done during the Soviet Topaz Nuclear Power System (NPS) missions.

This paper first considers the underlying nuclear physics and then explores the potential application of that science to the propulsion of merchant ships. It then examines the options for the exploitation of nuclear technology and considers some of the engineering implications of deploying the technology. Consideration is then given to the application of nuclear propulsion to a series of ship types, including tankers, container ships and cruise vessels. In each case two sizes of ship are chosen, one of fairly conventional size and the other much larger.

Studies over the last decade have shown radioisotope-based nuclear electric propulsion to be enhancing and, in some cases, enabling for many potential robotic science missions. Also known as radioisotope electric propulsion (REP), the technology offers the performance advantages of traditional reactor-powered electric propulsion (i.e., high specific impulse propulsion at large distances from the Sun), but with much smaller, affordable spacecraft. Future use of REP requires development of radioisotope power sources with system specific powers well above that of current systems. The US Department of Energy and NASA have developed an advanced Stirling radioisotope generator (ASRG) engineering unit, which was subjected to rigorous flight qualification-level tests in 2008, and began extended lifetime testing later that year. This advancement, along with recent work on small ion thrusters and life extension technology for Hall thrusters, could enable missions using REP sometime during the next decade.

Questions concerning the development of propulsion nuclear power systems are examined. The priorities for promising systems for the naval and civilian fleets are determined-reliability and survivability, secretiveness, safety, technical-economic indicators, ecology. Each group of requirements is analyzed in detail. Special attention is focused on the direction of development of reactor cores for nuclear-powered propulsion systems.

The main results of the work done at the Research and Design Institute of Electrical Technology on the development of designs and the creation of nuclear steam-producing systems (SPS) for propulsion are presented: the SPS VM-A for the first Soviet nuclear powered submarine, the SPS V-5 for the most powerful and fastest submarine with design 661 in the world team, and the designs of the first SGS MBU-40 with an integrated reactor. The basic technical solutions incorporated in the design of an integrated reactor for an advanced steam generating system are described.

This is the last in a series of papers on the effectiveness of using magnetohydrodynamically driven vortices to contain uranium in a gas core nuclear propulsion system. This paper evaluates the overall system performance, with particular focus on optimizing the power conversion system that supplies electrical power to the magnetohydrodynamic drive. The system is unique in that it is essentially nuclear thermal, however, it requires a large recirculation of electrical power. Although the assumed power conversion system is thermodynamic (Brayton) it is shown that this conversion can be accomplished either with a greatly reduced radiator area or, under some circumstances, without the need for radiators at all, by sinking waste heat into the propellant stream. A baseline set of system parameters is presented.

The possibility of decreasing the capital cost of building a nuclear power plant by unifying the equipment and technological processes is examined for the example of the experience in building and operating propulsion nuclear power-generating units. It is shown that it is desirable to adopt for nuclear power plants the most effective solutions and organizational-technical, and technological approaches which have been implemented in the development of propulsion nuclear power systems.

In an effort to further refine potential point of departure nuclear thermal rocket engine designs, four proposed engine designs representing two thrust classes and utilizing two different fuel matrix types are designed and analyzed from both a neutronics and thermodynamic cycle perspective. Two of these nuclear rocket engine designs employ a tungsten and uranium dioxide cermet (ceramic-metal) fuel with a prismatic geometry based on the ANL-200 and the GE-710, while the other two designs utilize uranium-zirconium-carbide in a graphite composite fuel and a prismatic fuel element geometry developed during the Rover/NERVA Programs. Two engines are analyzed for each fuel type, a small criticality limited design and a 111 kN (25 klbf) thrust class engine design, which has been the focus of numerous manned mission studies, including NASA's Design Reference Architecture 5.0. slightly higher T/W ratios, but they required substantially more 235U.

The fundamental capability of Nuclear Thermal Propulsion (NTP) is game changing for space exploration. A first generation NTP system could provide high thrust at a specific impulse above 900 s, roughly double that of state of the art chemical engines. Characteristics of fission and NTP indicate that useful first generation systems will provide a foundation for future systems with extremely high performance. The role of a first generation NTP in the development of advanced nuclear propulsion systems could be analogous to the role of the DC- 3 in the development of advanced aviation. Progress made under the NTP project could also help enable high performance fission power systems and Nuclear Electric Propulsion (NEP).

In FY11, NASA formulated a plan for Nuclear Thermal Propulsion (NTP) development that included Foundational Technology Development followed by system-level Technology Demonstrations The ongoing NTP project, funded by NASAs Advanced Exploration Systems (AES) program, is focused on Foundational Technology Development and includes 5 key task activities:(1) Fuel element fabrication and non-nuclear validation testing of heritage fuel options;(2) Engine conceptual design;(3) Mission analysis and engine requirements definition;(4) Identification of affordable options for ground testing; and(5) Formulation of an affordable and sustainable NTP development program Performance parameters for Point of Departure designs for a small criticality-limited and full size 25 klbf-class engine were developed during FYs 13-14 using heritage fuel element designs for both RoverNERVA Graphite Composite (GC) and Ceramic Metal (Cermet) fuel forms To focus the fuel development effort and maximize use of its resources, the AES program decided, in FY14, that a leader-follower down selection between GC and cermet fuel was required An Independent Review Panel (IRP) was convened by NASA and tasked with reviewing the available fuel data and making a recommendation to NASA. In February 2015, the IRP recommended and the AES program endorsed GC as the leader fuel In FY14, a preliminary development schedule DDTE plan was produced by GRC, DOE industry for the AES program. Assumptions, considerations and key task activities are presented here Two small (7.5 and 16.5 klbf) engine sizes were considered for ground and flight technology demonstration within a 10-year timeframe; their ability to support future human exploration missions was also examined and a recommendation on a preferred size is provided.

Nuclear thermal propulsion (NTP) has been recognized as an enabling technology for missions to Mars and beyond. However, one of the key challenges of developing a nuclear thermal rocket is conducting verification and development tests on the ground. A number of ground test options are presented, with the Sub-surface Active Filtration of Exhaust (SAFE) method identified as a preferred path forward for the NTP program. The SAFE concept utilizes the natural soil characteristics present at the Nevada National Security Site to provide a natural filter for nuclear rocket exhaust during ground testing. A validation method of the SAFE concept is presented, utilizing a non-nuclear sub-scale hydrogen/oxygen rocket seeded with detectible radioisotopes. Additionally, some alternative ground test concepts, based upon the SAFE concept, are presented. Finally, an overview of the ongoing discussions of developing a ground test campaign are presented.

The fundamental capability of Nuclear Thermal Propulsion (NTP) is game changing for space exploration. A first generation NTP system could provide high thrust at a specific impulse (Isp) above 900 s, roughly double that of state of the art chemical engines. Characteristics of fission and NTP indicate that useful first generation systems will provide a foundation for future systems with extremely high performance. The role of a first generation NTP in the development of advanced nuclear propulsion systems could be analogous to the role of the DC-3 in the development of advanced aviation systems.

The purpose of this paper is to investigate, facilitate a discussion and determine a path forward for technology development of cryogenic fluid management technology that is necessary for long duration deep space missions utilizing nuclear thermal propulsion systems. There are a number of challenges in managing cryogenic liquids that must be addressed before long durations missions into deep space, such as a trip to Mars can be successful. The leakage rate of hydrogen from pressure vessels, seals, lines and valves is a critical factor that must be controlled and minimized. For long duration missions, hydrogen leakage amounts to large increases in hydrogen and therefore vehicle mass. The size of a deep space vehicle, such as a mars transfer vehicle, must be kept small to control cost and the logistics of a multi launch, assembled in orbit vehicle. The boil off control of the cryogenic fluid is an additional obstacle to long duration missions. The boil off caused by heat absorption results in the growth of the propellant needs of the vehicle and therefore vehicle mass. This is a significant problem for a vehicle using nuclear (fission) propulsion systems. Radiation from the engines deposits large quantities of heat into the cryogenic fluid, greatly increasing boil off beyond that caused by environmental heat leakage. Addressing and resolving these challenges is critical to successful long duration space exploration. This paper discusses the state of the technology needed to address these challenges and discuss the path forward needed in technology development.

A novel concept of nuclear thermal rocket (NTR) propulsion is presented. It is based on the direct conversion of the kinetic energy of the fission fragments (FFs) into the propellant enthalpy. A sufficiently large surface coated with a few micrometers of Americium 242 m, confined by a neutron diffuser, can become a critical reactor, in which the FFs can escape from the thin layer of fissionable material. The novel FF NTR propulsion concept can allow the propellant to achieve temperatures higher than the nuclear fuel, thus overcoming the limit in the specific enthalpy imposed on the propellant in the conventional solid-core NTR propulsion. A preliminary assessment of the FF NTR concept's propulsion characteristics has been carried out using an in-house developed software system that integrates a computational-fluid-dynamic code, a neutronic code and a Monte Carlo code. The assessment shows the potential to reach specific impulses of about 15,000 m/s and thrust levels in the range 4000 to 6000 N, with a thrust-to-weight ratio of a few percent of the acceleration of gravity. Such performance can make the FF propulsion a candidate for human missions to the planet Mars.

In March 1939, Dr. Ross Gunn of the Naval Research Laboratory initiated a research program that would lay the groundwork for applying nuclear energy to submarine propulsion. The Navy contracts that followed initiated the first practical research into uranium production and isotope separation, and produced a practical method for uranium hexafluoride production (a process still used today). However, by the end of World War II the Navy's program had been absorbed by the Army's Manhattan Engineering District. This paper argues that the Navy, not the Army, deserves credit for laying the groundwork for nuclear energy in the united States. Although the atomic bomb was built by the Manhattan Engineering District under General Leslie Groves, the little-known and nearly suppressed story of the Navy's prior work in this field gives credence to Dr. Ross Gunn's claim that the Navy has been denied the credit it deserves. How and why the Navy was cut out of nuclear research and how the story was ignored illuminates another side of the first military applications of nuclear energy.

In the present work, a procedure for preliminary design optimization of a steam generator has been developed with the objective of minimizing the weight of the generator. Some real engineering constraints are considered in the problem formulation. A method of evaluating the objective function and constraints of the problem is presented. The problem has been solved numerically by using the exterior SUMT in which the Powell unconstrained minimization technique improved by Sargent with the parabolic interpolation method of one-dimensional minimization, is employed. The results of the optimum design and a sensitivity analysis conducted about the optimum point have been reported.

It has been about 40 years since nuclear-powered merchant ships were seriously discussed in the naval architecture community. But recent developments in commercial shipping include bigger, faster, and more powerful ships, where nuclear propulsion may be an option worth considering. The development of advanced ship designs opens an opportunity for high-speed maritime transportation that could create new markets and recover a fraction of the high value goods currently shipped only by air. One of the vessels being considered is FastShip, a large monohull ship that would require 250 MW in 5 gas turbine-waterjet units. An estimate of the operation cost of FastShip reveals that its success relies heavily, among other things, on the fuel price, a single factor that comprises more than one third of the total operating costs. The alternative, a nuclear FastShip, would save, per trip, almost 5000 tons of exposure to fuel price fluctuation, and about half of this savings would further be available for additional cargo and revenues. Nuclear power results in a more stable operation due to the relatively constant low price of nuclear fuel. The nuclear power option is suitable for high-power demand and long-haul applications and a reactor pack could be available within the decade. A candidate design would be the helium-cooled reactor, which has been revisited by several nuclear reactor design teams worldwide. For the FastShip a suggested plant would consist of two modular helium reactors, each one with two 50 MW helium turbines and compressors geared to waterjet pumps, plus a single 50 MW gas turbine. This vessel becomes more expensive to build but saves in fuel, and still provides margin for cost, weight and size optimization. This paper discusses general characteristics of a FastShip with such a nuclear power plant and also highlights the benefits, drawbacks, pending issues and further opportunities for nuclear-powered high-speed cargo ships.

This paper conducts a preliminary feasibility study on a novel global mobility and multimission Mars exploration platform, Mars Aerial Nuclear Global Landing Explorer(MANGLE). MANGLE is an aerial and ground system powered by nuclear propulsion to fly in Martian atmosphere with vertical take-off/landing capability. The Martian atmosphere, composed of 95.3% carbon-dioxide, will be used as propellant for an air-breathing engine heated by a fission nuclear reactor based on the open Brayton cycle. The engine will generate both thrust and accessory power. The cruise Mach number of MANGLE is 0.41. The engine power required is 2.1MW at takeoff/landing and 0.4MW at cruise. The total system mass is 899kg. The low weight of the vehicle is attributed to the lack of carried on propellant and radiator as well as the extremely high power and energy density of nuclear fission. The ultra-high lift co-flow jet flow control airfoil will be implemented on the blended wing-body configuration to achieve a cruise lift coefficient of 3.5, which is 5 to 10 times higher than a conventional airfoil. MANGLE will not only perform a scientific mission to investigate the Martian atmosphere, but will also land to collect soil samples at locations of interest observed from aerial survey. A deep drill of the soil sample up to 1 meter or more is possible due to the high shaft power from the air-breathing engine. MANGLE can transport the acquired ground samples to a base on Mars for sophisticated examination. The MANGLE mission period is one Martian year in order to investigate the seasonal variation of the atmosphere and surface soil. MANGLE will fly for 2/3 of the total mission time to survey the atmosphere and surface and the remaining 1/3 of the time will be spent on the ground for surface sample collection and examination. The range is sufficient to circle Mars 160 times during the mission.The preliminary feasibility study indicates that the MANGLE concept is feasible and the required technologies are achievable. MANGLE will revolutionize Martian scientific missions by enormously increasing the mobility in the atmosphere and on the ground, significantly benefiting mankind’s efforts to explore the Martian planet.

To support the on-going nuclear thermal propulsion effort, a state-of-the-art non nuclear experimental test setup has been constructed to evaluate the performance characteristics of candidate fuel element materials and geometries in representative environments. The facility to perform this testing is referred to as the Nuclear Thermal Rocket Element Environment Simulator (NTREES). This device can simulate the environmental conditions (minus the radiation) to which nuclear rocket fuel components will be subjected during reactor operation. Prototypical fuel elements mounted in the simulator are inductively heated in such a manner so as to accurately reproduce the temperatures and heat fluxes which would normally occur as a result of nuclear fission in addition to being exposed to flowing hydrogen. Recent upgrades to NTREES now allow power levels 24 times greater than those achievable in the previous facility configuration. This higher power operation will allow near prototypical power densities and flows to finally be achieved in most prototypical fuel elements.

This paper summarizes the advantages of space nuclear power and propulsion systems. It describes the actual status of international power level dependent spacecraft nuclear propulsion missions, especially the high power EU-Russian MEGAHIT study including the Russian Megawatt-Class Nuclear Power Propulsion System, the NASA GRC project and the low and medium power EU DiPoP study. Space nuclear propulsion based mission scenarios of these studies are sketched as well.

Some major risks-of-failure issues for the future manned missions to Mars are addressed. The specific complexity of the mission with the necessity of new and important technological developments has considerable implications in terms of risk estimation and management. The latest NASA reference mission is addressed and is commented on. It is concluded that the present design strategies are unable to provide sufficiently high reliability for the success of the mission. Several recommendations are proposed in this paper. The focus is on two categories of reliability problems. The first category concerns systems without clear accelerated testing capabilities, such as those for nuclear propulsion or entry-descent-and-landing. Several expensive precursor missions will have to be implemented to increase the maturity of the systems and to achieve the required level of reliability. Since cost is an important decision making parameter, it is suggested to determine the relationships between the different maturity models and their costs. For the entry-descent- and-landing phase, the proposed approach suggests a clear advantage of the 70° sphere cone heat shields. The second category concerns human-in-the-loop systems. Though different situations exist (e.g., maintenance, manual control, repairing), the same predictive model can be used to determine the probability of failure. The specific example of an ISRU option with robotic excavators and the possible intervention of astronauts is suggested. The preliminary conclusion is that astronauts with appropriate tools can be trained to increase the human capacity factor and reach an acceptable reliability level for the fueling process.

Recent studies on human missions to Mars suggest revisiting the parameters that have the most important impact on the complexity, the initial mass in low Earth orbit, the risks and the development costs for the first journey to the red planet. In the last NASA reference mission, a trade tree is proposed. At first level, the parameter is the class of mission, e.g., conjunction (long surface stay) or opposition (short surface stay). This parameter is important but there is an agreement on the best option (conjunction). It is therefore not a relevant parameter of the decision tree. For the other levels, the parameters are as follows: • Launching sequence: pre-deploy or all-up. • Mars orbit insertion: aerocapture or propulsive. • Exploitation of local resources: yes/no. • Propulsion for interplanetary flight: chemical/nuclear thermal/electric. The relevance of these parameters is questionable. It is proposed to reexamine all parameters of the mission and to study their interdependency and the complexity and the costs of possible options. The first important parameter should be the size of the crew. It should be assigned to the top node of the tree, because its impact on the initial mass in low Earth orbit, costs and risks is probably higher than any other parameter. Another parameter is the strategy for Mars orbit insertion. It is suggested here that aerocapture is very important and that it brings acceptable constraints for the architecture of the mission. The third parameter should be the strategy for entry, descent and landing. The mass of the landing vehicle is very important, because it is tightly linked to the complexity of the entry, descent and landing phase. With a low mass, a capsule shape and a rigid heat shield can be chosen for this maneuver (lowest risk, highest technology readiness level). With a heavy vehicle, an inflatable heat shield might help but the qualification of the systems would be very difficult and the entry, descent and landing phase would be more complex. This parameter is clearly a driving parameter for the design of mission architecture because this part is one of the riskiest (clearly established in the NASA report), one of the most expensive in terms of development and tests costs and there are obvious impacts on other parameters of the mission. The fourth parameter should be the strategy for the return and the preparation of the Earth return vehicle. According to our study, this vehicle is the heaviest of the mission. Critical choices can be made here and can make a scenario simple or very complex. Interestingly, a small crew size facilitates the reduction of the mass for the landing vehicles, which in turn suggests simple solutions for the aerocapture of all vehicles and the preparation of the Earth return vehicle without requiring the development of nuclear propulsion systems. All in all, this study shows that the choices made for the NASA reference mission are systematically suboptimal and that new options deserve to be explored.

Those who fear development of nuclear propulsion for space travel forget that considerable work on it has already been done, starting in the 1950s, and that the concept of a nuclear rocket was safely and successfully tested in the 1960s. This article describes the history of the US Nuclear Engine for Rocket Vehicle Application programme, with technical details of its development. Although funding for the programme ceased in the 1970s, there is no reason to suppose that the concept would not work today.

The potential benefits to humankind of space exploration are tremendous. Space is not only the final frontier but is also the next marketplace. The orbital space above Earth offers tremendous opportunities for both strategic assets and commercial development. The critical obstacle retarding the use of the space around the Earth is the lack of low cost access to orbit. Further out, the next giant leap for mankind will be the human exploration of Mars. Almost certainly within the next 30 years, a human crew will brave the isolation, the radiation, and the lack of gravity to walk on and explore the Red planet. Both of these missions will change the outlook and perspective of every human being on the planet. However, these missions are expensive and extremely difficult. Chemical propulsion has demonstrated an inability to achieve orbit cheaply and is a very high-risk option to accomplish the Mars mission. An alternative solution is to develop a high performance propulsion system. Nuclear propulsion has the potential to be such a system. The question will be whether humanity is willing to take on the challenge.

˜A new simplie ed approach is developed to analyze the performance of alternative propulsion systems with an additional power source, such as augmented catalytic, nuclear, and electrical propulsion systems. The optimum performance characteristics are calculated for missions with a e xed time of e ight, constant thrust, or constant mass e ow rate, considering the effects of propellant density, tankage fraction, and chemical enthalpy of propellants. A sensitivity analysis is employed to determine the ine uence of different parameters on mass efe ciency.

There is a large discrepancy between potential needs for nuclear propulsion and power systems for the human exploration of Mars and the current status of R&D funding, public opinion, and governmental support for these technologies. Mission planners and spacecraft designers, energized by the recent claims of possible discovery of life on Mars and responding to increased public interest in the human exploration of Mars, frequently propose nuclear reactors and radioisotope thermoelectric generators (RTGs) for interplanetary spacecraft propulsion and for power supply on the surface of Mars. These plans and designs typically assume that reactors will be available "on-the-shelf," and do not take the extensive R&D costs required to develop such reactors into consideration. However, it is likely that current U.S. policies, if unchanged, will prohibit the launch of nuclear reactors and large RTGs in response to a perceived risk by the public.

The present and past activities of Ministry of Defence (MOD) have resulted in the production of radioactive waste, particularly from the naval nuclear propulsion programme and the nuclear weapons programme. The MOD manages radioactive waste in accordance with national policy and regulation, making use of disposal options where available. MOD radioactive waste management practices are subject to independent review and regulation.

The history of civil nuclear-powered vessels development in Russia is highlighted. Advantages of nuclear propulsion for icebreakers operating in the Arctic are discussed. The operation of nuclear-powered icebreakers and the nuclear lighters-aboard ship in the Arctic has changed the situation on the Northern Sea Way. The all year round navigation there now is a reality. The reliability, safety and ecological cleanness of nuclear-powered vessels are discussed. The necessity of internationally recognized standards, rules and codes for safe operation of nuclear-powered trade vessels is underlined.

Nuclear Thermal Propulsion (NTP) is a concept which uses a nuclear reactor to heat a propellant to high temperatures without combustion and can achieve significantly greater specific impulse than chemical engines. NTP has been considered many times for human and cargo missions beyond low earth orbit. A lot of development and technical maturation of NTP components took place during the Rover/NERVA program of the 60's and early 70's. Other NTP programs and studies followed attempting to further mature the NTP concept and identify a champion customer willing to devote the funds and support the development schedule to a demonstration mission. Budgetary constraints require the use of an affordable development and qualification strategy that takes into account all the previous work performed on NTP to construct an existing database, and include lessons learned and past guidelines followed. Current guidelines and standards NASA uses for human rating chemical rocket engines is referenced. The long lead items for NTP development involve the fuel elements of the reactor and ground testing the engine system, subsystem, and components. Other considerations which greatly impact the development plans includes the National Space Policy, National Environmental Policy Act, Presidential Directive/National Security Council Memorandum #25 (Scientific or Technological Experiments with Possible Large-Scale Adverse Environmental Effects and Launch of Nuclear Systems into Space), and Safeguards and Security. Ground testing will utilize non-nuclear test capabilities to help down select components and subsystems before testing in a nuclear environment to save time and cost. Existing test facilities with minor modifications will be considered to the maximum extent practical. New facilities will be designed to meet minimum requirements. Engine and test facility requirements are based on the driving mission requirements with added factors of safety for better assurance and reliability. Emphasis will be placed on small engines, since the smaller the NTP engine, the easier it is to transport, assemble/disassemble, and filter the exhaust during tests. A new ground test concept using underground bore holes (modeled after the underground nuclear test program) to filter the NTP engine exhaust is being considered. The NTP engine system design, development, test, and evaluation plan includes many engine components and subsystems, which are very similar to those used in chemical engines, and can be developed in conjunction with them Other less mature NTP engine components and subsystems (e.g., reactor) will be thoroughly analyzed and tested to acceptable levels recommended by the referenced standards and guidelines. The affordable development strategy also considers a prototype flight test, as a final step in the development process. Preliminary development schedule estimates show that an aggressive development schedule (without much margin) will be required to be flight ready for a 2033 human mission to Mars.

Introduction 1. Global HEU Phase-Out: Prospects & Challenges Alan J. Kuperman Success Stories 2. Argentina: Medical Isotope Production Jared Berenter 3. South Africa: Reactor Fuel and Medical Isotope Production Chloe Colby Hopeful Progress 4. USA and Europe: High-Power Research Reactors Margarita Jimenez 5. Russia: Icebreaker Ships and Floating Reactors Christine Egnatuk 6. Belgium and the Netherlands: Medical Isotope Production Alexander Fay 7. China: Reactors and Nuclear Propulsion, Shing-yao (Sandra) Feng Stubborn Civilian Commerce 8. Germany: The FRM-II Reactor Kenneth Dayman 9. Canada and Russia: Medical Isotope Production Kendra Vessels 10. Russia: Research Reactors Braden Civins 11. Russia: Critical Assemblies and Pulsed Reactors Paul Osborne Military Challenges 12. USA and France: Naval Propulsion Rebecca Ward 13. Russia: Naval Propulsion Yaroslav Primachenko Ahead of the Curve 14. Space Reactors R. Blake Messer Conclusion 15. Achieving a Global HEU Phase-Out Alan J. Kuperman

Conventional propulsion technology (chemical and electric) currently limits the possibilities for human space exploration to the neighborhood of the Earth. If farther destinations (such as Mars) are to be reached with humans on board, a more capable interplanetary transfer engine featuring high thrust, high specific impulse is required. The source of energy which could in principle best meet these engine requirements is nuclear thermal. However, the nuclear thermal rocket technology is not yet ready for flight application. The development of new materials which is necessary for the nuclear core will require further testing on ground of full-scale nuclear rocket engines. Such testing is a powerful inhibitor to the nuclear rocket development, as the risks of nuclear contamination of the environment cannot be entirely avoided with current concepts. Alongside already further matured activities in the field of space nuclear power sources for generating on-board power, a low level investigation on nuclear propulsion has been running since long within ESA, and innovative concepts have already been proposed at an IAF conference in 1999 [1, 2]. Following a slow maturation process, a new concept was defined which was submitted to a concurrent design exercise in ESTEC in 2007. Great care was taken in the selection of the design parameters to ensure that this quite innovative concept would in all respects likely be feasible with margins. However, a thorough feasibility demonstration will require a more detailed design including the selection of appropriate materials and the verification that these can withstand the expected mechanical, thermal, and chemical environment. So far, the predefinition work made clear that, based on conservative technology assumptions, a specific impulse of 920 s could be obtained with a thrust of 110 kN. Despite the heavy engine dry mass, a preliminary mission analysis using conservative assumptions showed that the concept was reducing the required Initial Mass in Low Earth Orbit compared to conventional nuclear thermal rockets for a human mission to Mars. Of course, the realization of this concept still requires proper engineering and the dimensioning of quite unconventional machinery. A patent was filed on the concept. Because of the operating parameters of the nuclear core, which are very specific to this type of concept, it seems possible to test on ground this kind of engine at full scale in close loop using a reasonable size test facility with safe and clean conditions. Such tests can be conducted within fully confined enclosure, which would substantially increase the associated inherent nuclear safety levels. This breakthrough removes a showstopper for nuclear rocket engines development. The present paper will disclose the NTER (Nuclear Thermal Electric Rocket) engine concept, will present some of the results of the ESTEC concurrent engineering exercise, and will explain the concept for the NTER on-ground testing facility. Regulations and safety issues related to the development and implementation of the NTER concept will be addressed as well.