Conceptual core design study for Indonesian Space Reactor (ISR) (original) (raw)
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Space nuclear reactor concepts for avoidance of a single point failure
Nuclear reactor power systems could revolutionize space exploration and support human outpost on the moon and Mars. This paper reviews various energy conversion technologies for use in space reactor power systems and provides estimates of the system's net efficiency and specific power, and the specific area of the radiator. The suitable combinations of the energy conversion technologies and the nuclear reactors, classified based on the coolant type and cooling method, for best system performance and highest specific power, are also discussed. In addition, four space reactor power system concepts, developed at the University of New Mexico's Institute for Space and Nuclear Power Studies, with both static and dynamic energy conversion for nominal electrical powers up to 110 kWe, but no single point failures in reactor cooling, energy conversion and heat rejection, are presented. Two power systems employ liquid-metal heat pipes cooled reactors, thermoelectric (TE) and Alkali-Metal Thermal-to-Electric Conversion (AMTEC) units for converting the reactor power to electricity, and potassium heat pipes radiators. The third power system employs SiGe TE converters and a liquid metal cooled reactor, with a core divided into six identical sectors. Each sector has a separate energy conversion loop, a heat rejection loop, and a rubidium heat pipes radiator panel. The fourth power system has a gas cooled reactor, with a sectored core. Each of the three sectors in the core is coupled to a separate Closed Brayton Cycle (CBC) loop with He-Xe (40g/mole) working fluid and a Nak-78 secondary loop, and two separate water heat pipes radiator panels.
Reactor Start‐up and Control Methodologies: Consideration of the Space Radiation Environment
The use of fission energy in space power and propulsion systems offers considerable advantages over chemical propulsion. Fission provides over six orders of magnitude higher energy density, which translates to higher vehicle specific impulse and lower specific mass. These characteristics enable the accomplishment of ambitious space exploration missions. The natural radiation environment in space provides an external source of protons and high energy, high Z particles that can result in the production of secondary neutrons through interactions in reactor structures. Initial investigation using MCNPX 2.5.b for proton transport through the SAFE‐400 reactor indicates a secondary neutron net current of 1.4×107 n/s at the core‐reflector interface, with an incoming current of 3.4×106 n/s due to neutrons produced in the Be reflector alone. This neutron population could provide a reliable startup source for a space reactor. Additionally, this source must be considered in developing a reliabl...
Gas Core Reactor as a Technological Breakthrough for Long Range Space Missions
In the technological feasibility for the long range missions in the deep space exploration, nuclear propulsion has proven to be the most feasible method. Gas core reactor designs are opening up possibilities to the deep space exploration missions such as mission to various planets in the solar system and also to the Interstellar distances. This paper describes various challenges in the design of gas core reactor systems and methods to reduce the total radiation from the mission. To increase the scope of the mission we have to create very efficient reactor system. To create safe reactor designs, we have to control neutron spectrum within the limits without creating loss to the total energy density inside the reactor core. The refined designs consist of reflector, which will also act as an external moderator in place on all sides of the cavity. Specific approach on the cavity design in our approach is to have multiple cavities to increase neutron moderation and to help neutrons to thermalize by their own. In the long range missions, the reactor will be exposed to higher temperatures in the presence of higher limits of pressure. In case of UF6 in order to control chemical reactions within reactor core and to the coolant, we have to maintain absolute amount of pressure so that reaction will be stabilized. Another aspect of reactor design is proliferation resistance, since gas density will be a function of both pressure and temperature. In reality this is not the case, since the reflector is cooled and the fuel near to the reflector wall will have lower temperature than the core. In order to maintain the greater amounts of heat flux inside the reactor core creating relative amounts of turbulence in the coolant flow, so that it will allow reactor system to expose to grater energy density. Also we need to consider actinides and fission products inventory in the system design. In line of the above problems, this paper will talk about the various efficiencies in the gas core reactor design approach and radiation control and reactor fission kinetics. In addition, this paper will demonstrate that using nuclear reactors is within the realm of today’s technology and hence they can be used for long range missions as long as it satisfies the budget constraints.
Deployment history and design considerations for space reactor power systems
Acta Astronautica, 2009
The history of the deployment of nuclear reactors in Earth orbits is reviewed with emphases on lessons learned and the operation and safety experiences. The former Soviet Union's "BUK" power systems, with SiGe thermoelectric conversion and fast neutron energy spectrum reactors, powered a total of 31 Radar Ocean Reconnaissance Satellites (RORSATs) from 1970 to 1988 in 260 km orbit. Two of the former Soviet Union's TOPAZ reactors, with in-core thermionic conversion and epithermal neutron energy spectrum, powered two Cosmos missions launched in 1987 in ∼800 km orbit. The US' SNAP-10A system, with SiGe energy conversion and a thermal neutron energy spectrum reactor, was launched in 1965 in 1300 km orbit. The three reactor systems used liquid NaK-78 coolant, stainless steel structure and highly enriched uranium fuel (90-96 wt%) and operated at a reactor exit temperature of 833-973 K. The BUK reactors used U-Mo fuel rods, TOPAZ used UO 2 fuel rods and four ZrH moderator disks, and the SNAP-10A used moderated U-ZrH fuel rods. These low power space reactor systems were designed for short missions (∼0.5 kW e and ∼1 year for SNAP-10A, < 3.0 kW e and < 6 months for BUK, and ∼5.5 kW e and up to 1 year for TOPAZ). The deactivated BUK reactors at the end of mission, which varied in duration from a few hours to ∼4.5 months, were boosted into ∼800 km storage orbit with a decay life of more than 600 year. The ejection of the last 16 BUK reactor fuel cores caused significant contamination of Earth orbits with NaK droplets that varied in sizes from a few microns to 5 cm. Power systems to enhance or enable future interplanetary exploration, in-situ resources utilization on Mars and the Moon, and civilian missions in 1000-3000 km orbits would generate significantly more power of 10's to 100's kW e for 5-10 years, or even longer. A number of design options to enhance the operation reliability and safety of these high power space reactor power systems are presented and discussed.
Submersion-Subcritical Safe Space (S4) reactor
Nuclear Engineering and Design, 2006
The Submersion-Subcritical Safe Space (S 4 ) reactor, developed for future space power applications and avoidance of single point failures, is presented. The S 4 reactor has a Mo-14% Re solid core, loaded with uranium nitride fuel, cooled by He-30% Xe and sized to provide 550 kWth for 7 years of equivalent full power operation. The beryllium oxide reflector of the S 4 reactor is designed to completely disassemble upon impact on water or soil. The potential of using Spectral Shift Absorber (SSA) materials in different forms to ensure that the reactor remains subcritical in the worst-case submersion accident is investigated. Nine potential SSAs are considered in terms of their effect on the thickness of the radial reflector and on the combined mass of the reactor and the radiation shadow shield. The SSA materials are incorporated as a thin (0.1 mm) coating on the outside surface of the reactor core and as core additions in three possible forms: 2.0 mm diameter pins in the interstices of the core block, 0.25 mm thick sleeves around the fuel stacks and/or additions to the uranium nitride fuel. Results show that with a boron carbide coating and 0.25 mm iridium sleeves around the fuel stacks the S 4 reactor has a reflector outer diameter of 43.5 cm with a combined reactor and shadow shield mass of 935.1 kg. The S 4 reactor with 12.5 at.% gadolinium-155 added to the fuel, 2.0 mm diameter gadolinium-155 sesquioxide interstitial pins, and a 0.1 mm thick gadolinium-155 sesquioxide coating has a slightly smaller reflector outer diameter of 43.0 cm, resulting in a smaller total reactor and shield mass of 901.7 kg. With 8.0 at.% europium-151 added to the fuel, along with europium-151 sesquioxide for the pins and coating, the reflector's outer diameter and the total reactor and shield mass are further reduced to 41.5 cm and 869.2 kg, respectively.
SCoRe — Concepts of liquid metal cooled space reactors for avoidance of single‐point failure
AIP-CP-746, Space Technology and Applications International Forum (STAIF-2005), Albuquerque NM, 2005
Space nuclear Reactor Power Systems (SRPSs) are being developed to meet electrical power requirements for NASA’s planetary exploration missions early next decade. In addition to enjoying some degree of autonomy, these systems need to operate reliably through the end of the mission, which could not be realized solely through a redundancy in the reactor’s coolant loop. Besides increasing the total system mass, such hardware redundancy does not eliminate a single‐point failure in the reactor and subsequent loss of coolant. This paper presents three concepts of the liquid metal cooled. Sectored, Compact Reactor (SCoRe) for the avoidance of single‐point failure. The SCoRe‐S, ScoRe‐M, and SCoRe‐L concepts are for small, medium, and large reactor cores, covering a wide range of electrical power requirements, from 10’s of kWe to a few MWe. As a common feature in all SCoRe concepts, the reactor core is divided into six sectors that are neutronically coupled but thermal‐hydraulically decoupled. The dividers of the sectors are liquid metal heat pipes, which facilitate cooling a sector experiencing a Loss of Coolant (LOC) by passively transporting the fission power generated in it to the two adjacent sectors without losing the mission. At the same time, the fission power of the reactor is reduced to avoid overheating the fuel in the sector experiencing a LOC. The SCoRe concepts have compact, hexagonal cores surrounded by a relatively thick (10 cm minimum) BeO reflector and axial BeO reflector that is 4 cm thick. The SCoRe is placed directly in front of the radiation shield, thus reducing the shield mass and that of the power system. In SCoRe‐S cores, the UN fuel pins are arranged in a triangular lattice while in the SCoRe‐M and SCoRe‐L cores, the UN fuel pins arranged in a triangular lattice are assembled in 19‐pin and 37‐pin shrouded bundles, respectively. © 2005 American Institute of Physics.
Annals of Nuclear Energy, 1999
The critical neutron heating in the reflector control drums is investigated for a fast incore thermionic space craft reactor for power and nuclear propulsion. The reactor is fueled with uranium carbide (UC) and controlled with the help of rotating B4C drums imbedded into the beryllium reflector. While the neutron heating in the drums would not require a cooling mechanism in the power phase, the heat generation during the thrust phase obliges cooling for a nuclear thermal thrust around F= 5000 N by a specific impulse of 670s -I at an hydrogen exit temperature around 1900°K. With a beryllium reflector without extra cooling measures, thermal thrust must be kept F< 2500 N to relieve the thermal load in the reflector. On the other hand, a reflector made of BeO may withstand a thermal load for a nuclear thermal thrust of F= 5000 N. The neutronic analysis has been conducted in 816"P3 and Ss-P 3 approximation with the help of one-and two-dimensional neutron transport codes ANISN and DORT, respectively. A reactor control with boronated reflector drums (drum diame-ter= 14cm) at the outer periphery of the radial reflector of 16cm thickness would make possible reactivity changes of Akefr = 13.55%--amply suflicient for a fast reactor--without a significant distortion of the fission power profile during all phases of the space mission. Calculations are conducted for a reactor with a core radius of 22cm and core height of 35cm leading to power levels around 50 kWev
Colorado School of Mines. Arthur Lakes Library, 2019
A Low-Enriched Uranium (LEU) fueled space reactor would avoid the security concerns inherent with Highly Enriched Uranium (HEU) fuel and could be attractive to signatory countries of the Non-Proliferation Treaty (NPT) or commercial interests. This thesis considers the feasibility of an LEU-fueled kilopower-class space reactor based on mass-optimization and shielding considerations. The HEU-fueled Kilowatt Reactor Using Stirling TechnologY (KRUSTY) serves as a basis for a similar reactor fueled with LEU fuel. Zirconium hydride moderator is added to the core in four different configurations (a homogeneous fuel/moderator mixture and spherical, disc, and helical fuel geometries) to reduce the mass of uranium required to produce the same excess reactivity, decreasing the size of the reactor. All three heterogeneous geometries yield a minimum mass reactor using a moderator/fuel ratio of 80 wt%. The lifetime is directly proportional to the initial amount of fissile material in the core in all the cases. Based on the small differences in estimated masses, but large difference in estimated lifetimes, between the 60 wt% and 80 wt% moderated reactors, the 60 wt% moderated systems with disc or helical fuel geometries represent the best balance between total mass and operating lifetime. Based on the results of the mass-optimization study, the thesis considers shadow shield options for an unmoderated HEU-fueled space reactor and a moderated LEU-fueled space reactor. Both reactors are kilowatt-class reactors, producing 15 kWth of thermal power over a 5year operational lifetime. Based on the shielding required to meet established dose limits (a neutron fluence of less than 10 14 n/cm 2 (>1 MeV equivalent in silicon) and a gamma ray dose of less the 1 Mrad in silicon), the moderated LEU-fueled space reactor will require a thicker shadow shield than the unmoderated HEU-fueled space reactor. The thinner reflector of the moderated LEU-fueled reactor results in more neutrons reaching the shadow shield at higher energies compared to the unmoderated HEU-fueled reactor. The presence of a significant reflector in most space reactor designs means that the core spectrum is relatively unimportant in terms of shadow shield design, as the reflector thickness has a much stronger impact on the neutrons and gamma rays reaching the shadow shield. v TABLE OF CONTENTS
Submersion criticality safety of fast spectrum space reactors: Potential spectral shift absorbers
Nuclear Engineering and Design, 2006
Compact, fast spectrum, nuclear reactors are being considered to support NASA's future space exploration sometime in the next decade. In order to secure launch approval, these reactors should remain sufficiently subcritical when submerged in seawater or wet sand and subsequently flooded, following a launch abort accident. In such an accident, the neutron spectrum in the reactor is thermalized, typically increasing reactivity, and potentially making the reactor supercritical. Incorporating "Spectral Shift Absorbers" (or SSAs), which have significantly higher absorption cross-sections for thermal versus fast neutrons, could offset the reactivity increase. It has always been the assertion that the worst-case submersion accident involves a fully flooded reactor; however, this work shows that, depending on the type and amount of SSA in the reactor, a submerged but unflooded reactor could be more reactive. A screening of the existing nuclear database for potential SSAs yielded 28 elements and nuclides, which are examined in detail as additives to a representative homogenous space reactor core by varying the SSA-to-U 235 atom ratio. The effect of placing a thin coating of different SSA materials on the outside surface of the reactor core is also investigated. Nine SSAs (boron-10, cadmium, cadmium-113, samarium-149, europium-151, gadolinium, gadolinium-155, gadolinium-157, and iridium) are recommended for further consideration in actual space reactor designs. (M.S. El-Genk).