by Bruce Behrhorst

    I glanced at my wrist watch 11:15 am.

  I figured I had missed attendance at the press conference with NASA's new Director, Mike Griffin out at the Kennedy Space Center, but arrived well in advance of NASA's first of three in a series of public meetings over research and development associated with nuclear fission reactors to produce electrical power and usher thermal nuclear thrust reactor systems for potential use in space for future NASA exploration missions. The meetings are designed as with all government agencies that plan for future development as intent to scope public comment known as complying with the National Environmental Policy Act of 1969 (NEPA).

  I had not been in this area of Florida's north coast since I was a young high school swimmer in the breaststroke competing in a Amateur Athletic Union (AAU) swimming event held in the same area. Back then there was no NEPA or Space Shuttle. Of course now the area had grown immensely so getting acquainted with the area meant driving east down highway 528 (Beeline express way) off of Interstate 95. As I approached the Causeway I happen to notice new construction of a wider span to the bridge over the Indian River.
  You have a choice, you could drive to the KSC (Kennedy Space Center) visitor complex and see the Astronaut Hall Of Fame, the Space Shuttle Landing Facility which is the Space Port Complex or turn along to the Sea Port of Canaveral to the pleasure cruise lines were ships arrive and depart. Both ports-of-call basically serve the same function, to move equipment and people.

  I chose solace heading south down route AIA to of all places; the Cocoa Beach Fishing Pier dressed in shoes, socks, pants and the proverbial pen stuck in my shirt pocket, dark eye shades and a lunch bucket in tow headed toward the beach to gaze across the Atlantic Ocean, receiving stares from wet suited surfers and beach bathers. They probably thought, "What kind of geek would step upon a fun place like this, out of dress?" I spotted a huge 4 foot diameter dredge pipe designed to pump sand onto the beach from a Dredger anchored off the beach shoreline to enlarge the beach line real estate. I always thought this was a silly perpetual work-in-progress practice in Florida, only because all it would take is a powerful storm or Hurricane to completely ruin the work that "Time" and "Sea Water" want to claim back from the man-made beach. I hopped on the rusty pipe, opened my lunch bucket thinking to myself as I took a bite off my smoked fish spread sandwich.
  Damn... This is a "Sea" of change for the space agency since a recent Bush presidency statement of opening "New" horizons in space with a vision on pro-activity in human ventures on the Moon, Mars and beyond. The expansion of powerful robotics in space capable of responding more quickly to powerful communications generating vast amounts of data. All this comes at a time when a return to flight status for the Space Shuttle following the tragedy and loss of life to the Astronaut Corps two years ago. Frankly, I tend to empathize with the space agency's desire to change under a difficult period in its life. I, like most people have had to do the same. Change is painful. I had to look at the positive side of the equation if only because I grew tried of thinking of the negative. NASA does have a new director, which leaves you with the impression that sober thought and methodical management reminiscent of more successful times in NASA's history. Both the Public and agency's desire to return the country toward self sufficiency operations in space are admirable. And most important a recognition that the agency will have to embrace sooner rather that later the need to make use of the "Nuclear Tool" despite the risks for power and propulsion as a good faith measure to ensure safety and efficiency of space nuclear operations in order to realistically permit ventures NASA and the public want to pursue for this expanded "Vision" in space exploration and space commerce. After all for whatever the fashionable rationale for space travel might be in the future, it's the same need to move people and equipment to destinations in our solar system and beyond. To colonize and thus ensure survivability of human species. It's an inescapable common thread between our ancestors and us; as it is with "Time" and "Sea Water" constantly eroding to reclaim the beach shoreline.

Shared my last bite with the Sea Gulls and went to the meeting.

 Upon arriving at the Florida Solar Energy Center; H. George Carrison Auditorium near Brevard Community College which seemed to me ironic, the choice of a solar energy center as a first meeting place to inform the Public over future nuclear space practices rationale.
  Solar energy in space represents a limited operational capability. Solar energy as a function of distance from the Sun for example; at Earth the Solar Energy (SE) Flux is 1.0, at 1 AU distance at Mars it's cut in half 0.5 SE Flux, at 2 AU Jupiter SE Flux is 0.1, at 5 AU the SE Flux is at 0.0, at 10AU distance means solar energy is negligible for solar electrical power. Besides solar energy is one taken to careful measured steps at lower bandwidth albeit low wattage. It does have a place for some aspects in future inner solar system space missions with the combination of solar power and battery mission requirements, but nowhere near the capacity as a main power and propulsion source nuclear energy can bring to service future robust missions. I none the less read the NASA Prometheus presentation material handouts.

PROMETHEUS GOALS

 NASA currently is embarked on space-based demonstrations to provide necessary practical design, manufacturing and operating experience before using any new technologies on more complex space missions.

 NASA at this time is conducting an Analysis of Alternatives with the assistance of the Department of Energy, and (All nuclear materials used in nuclear reactors fall under the purview of the DOE signed into law, Atomic Energy Act of 1954 & The Dept. of Energy Organization Act, 42 U.S.C. §7101 et seq.) Office of Naval Reactors (DOE-NR). The purpose of the Analysis of Alternatives is to define possible missions that could be used to demonstrate the operability of technological capabilities that could enable more challenging scientific missions such as exploring the outer reaches of our solar system. If NASA were to actually develop a space nuclear fission reactor the initial Prometheus mission might be launched as early as 2014. In any event the first mission would be technologies developed to support fission reactor power, advanced telecommunication systems, high rate data transmission systems, high temperature materials and advanced power conversion systems would significantly provide NASA's exploration needs. The safety issue with nuclear systems is a "Bone of Contention" with the Public in part because "Main Stream Media" never real quite educate or report on the facts in nuclear matters. They generally gloss over information that provides fair nuclear science information and practice and elect to sensationalize events dealing with the nuclear issue, after all they operate on the premise to sell services not educate or inform.

  Historically, the U.S. has an excellent safety record using nuclear power in space exploration with more than 40 years experience in successful management and operations. NASA is in partnership with the Department of Energy's Office of Naval Reactors (DOE-NR) within the National Nuclear Security Administration (NNSA) to develop a space nuclear reactor for use in future robotic exploration activities. The Office of Naval Reactors (NR) is a joint Navy-DOE organization having responsibility and authority in both agencies. The Secretary of Energy assigned NR to partner with NASA in support of Prometheus solely as a DOE civilian project. Besides having over 52 years experience in compact nuclear power plants in designing reactors for the rigors of marine use and combat scenarios. The recent accidental grounding of the Navy's nuclear powered attack submarine "San Francisco" highlighted the durability a U.S. naval reactors at sea. DOE-NR is experienced in bringing to completion successful "First Of Its Kind" projects.

Responsibilities include:

• NR has 103 reactors operating worldwide.
• Nuclear powered fleet.
• Laboratories
• Shipyards
• Schools
• Specialized industrial base.
• R&D/training on reactors.

 Special projects include Shippingport Atomic Power Station the world's first solely commercial atomic power plant producing electricity for customers from 1957 to 1982. Demonstrating Light Water Breeder Reactor Technology. NR provided active oversight of all aspects of nuclear facility at shippingport from initial design through the defueling and decommissioning phases. In 1989 the DOE decommissioned Shippingport, removing all radioactive components and returning the site to greenfield conditions. NR also operates the NR-1 a nuclear-powered deep submergence research and ocean engineering vehicle.

DOE-NR To Prepare Safety Analysis Report Over Design, Operation And Safety.

DOE-NR has the responsibility for all aspects of reactor development including reactor safety. Safety is of primary importance in every facet of Prometheus including spacecraft design, test, manufacture, launch and operation. Safety is to be integrated into every element of the program through engineering requirements, design, and specification. DOE-NR is to inform its partnerships, including the public of intentions and provides ample opportunity for public input throughout the life of the program. DOE is to request the U.S. Nuclear Regulatory Commission conduct an independent safety review.

Safety launch sequence:

• NASA development activities for the spacecraft and launch vehicle would be done in concert with DOE-NR to fully understand and characterize the interactions between systems under potential accident scenarios to ensure that engineered safety systems protect the public.
• NASA's launch approval process for a spacecraft containing a space nuclear reactor requires multiple reviews before the spacecraft can be used for an exploration mission and numerous program office reviews.
• NASA Office of safety and Mission Assurance would conduct a separate, independent risk and safety assessment before the program could proceed.
• Require NASA satisfy the Presidential nuclear safety launch approval process described in 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."
• As part of the Presidential nuclear safety launch approval process an ad hoc Interagency Nuclear Safety Review Panel (INSRP) would be established to evaluate the nuclear evaluation report prepared for the proposed launch. INSRP representatives from the department of Defense, the Department of Energy , NASA and the Environmental Protection Agency., as well as other interested agencies would then evaluate the risks associated with that launch and prepare its recommendation for the President .
• Upon INSRP recommendation, NASA would request the President's Office of Science and Technology Policy (OSTP). The OSTP Director may make the launch approval decision or refer the matter to the President. In either case, the launch cannot proceed until nuclear safety launch approval has been granted.

[more info on EXPLORE/DISCOVER/UNDERSTAND]

SOME NASA SHORT FALLS

Again, some would ask, can NASA overcome it's current short falls?

 NASA's overall lack of strategy is now well known as was eluded to by the new NASA Director Griffin. In his first press conference acknowledging the fact NASA has been woeful in gaining focus. This is not surprising as it is with most of our society in general anti-intellectualism and excuse mechanisms seem to take on an approved resolve in just about any facet of society one would care to name; in government and business scandal is common in some sectors - obviously not in all.
  Dr. Robert Zubrin's treatise, "Getting Space Exploration Right" appearing in the spring of 2005 in publications like The New Atlantis, Spacedaily.com, Space.com and numerous space blogs on the internet. It has made eloquent note of inadequacies in the space agency, but these criticism should not be limited to NASA as a whole and as noted in the article, JPL (Jet Propulsion Lab) is not the only productive NASA field center there are others just as stellar in performance. Media just does not give the same public attention these other centers deserve; since the human part of space activity has been removed following recent circumstances. The article is correct in some aspects at pointing to managerial malaise. If one would focus out to include resolution on the status of our education system, at its core, it's in equally serious trouble. Almost one third of U.S. High school graduates students make it to pursue a College and University education in the sciences. The United States is 14th among the developed nations of the world to graduate College and University trained students. Since 1983 the population rate of U.S. College and University students has dropped precipitously. Policies like the "No Child Left Behind.." in place to correct this imbalance do little to improve the current state of U.S. primary education and the affordability of higher secondary education. A principle reason more students opt to move toward the workforce quickly to pay bills and the high cost of tuition rather than continue higher education and without well trained individuals no successful space program could ever get off the ground.

"Out-Source" A NATIONAL SPACE PROGRAM?

 Another facet of this transitory societal malaise is our National Lab System, constantly called into question and a favorite target of criticism in the current round of "National Lab Bashing" in Congress as politicians seem to contrive punitive measures threatening to turn over lab facilities like Los Alamos into glorified warehousing facilities over infractions in safety and lapses in security. As the chorus in criticism grows they neglect the vibrant contribution that participating research and development has contributed to our space program besides other fields of endeavor in service to the nation. It leaves the impression, some would argue, if no national plan was worthy then reliance on international technology would serve better? It's bad practice of offering criticism of the space agency and its other support institutions including aerospace corporations charging aerospace contractors with 'corporate welfare' when they participate on large projects without the offer of a constructive alternative or 'best method' to monitor waste and noncompliance.

HASTE PLANNING TO MARS

 Dr. Zubrin's paper under subtitle: "How Do We Get There" points to the Saturn V Booster essentially Redstone rockets strapped together although a wonderful lifter for the Apollo mission of the period.
He also is in favor according to his book, "The Case For Mars" the Ares 1 Booster to lift payloads to low Earth orbit, to throw them into interplanetary space in one shot. High over the Earth's atmosphere the Ares upper stage separates from the spent booster, and fires a single hydrogen+oxygen burning engine to pitch a 45 metric ton payload to Mars which is the Earth Return Vehicle (ERV) this ERV is equipped with a small nuclear reactor atop a light truck essentially an automated rocket fuel production plant used to manufacture fuel from the Martian atmosphere. Plus cabin stores for life support on the return 8 months trip back to Earth using two propulsion stages consuming approximately 96 tonnes of methane+oxygen bipropellant. Of course, 6 tonnes of Earth manufactured liquid hydrogen are also included on this ERV.

 Fine so far...all this stuff is riding on just one chemical rocket engine burning fuel like, there's no tomorrow. It is zipping along at a clip of 27km/sec and we really don't need to watch the 'time clock' except maybe hoping the earth supplied hydrogen is kept fresh and is usable when needed . No problem, it's only Martian mission equipment cargo not human cargo that at the end of 13 months has an ERV fully fueled, thanks to the nuclear reactor having combined the earth hydrogen into 108 tonnes of methane+oxygen rocket fuel on the Martian launch pad waiting arrival of its human crew for liftoff back to Earth.

 Ares 2 is launched this is habitation equipment, no problem here.

 Now, the day arrives for Ares 3 launch the human part of this Mars voyage when presumably after about one year everything done previous in support is running perfect, everything has worked without any technological snags or errors. Ares lifts off the pad the upper stage fires its own hydrogen+oxygen burning engine engine(s) and breaks away; driving the Hab to Trans-Mars cruise velocity. The pilot of the Hab direct away from the burnt-out upper stage of the booster, releasing it on a single 330 meter tether as it goes so the combination of the upper stage and Hab via a small rocket begins to rotate producing artificial gravity en route for the crew. I80 days (6 mo.) of flight later crew arrives at Mars. Oops..! What about the total mission elapsed 'time clock' that starts ticking away with regard to Space Radiation Health Risk for humans in transit and on the surface of Mars? I'm sure NASA radiation shielding and mitigation studies will revel adequate materials and practice to minimize effects on humans after a prolonged journey to Mars or Moon. Wouldn't it be wise to reduce any unnecessary time spent for both mission systems and human health by providing the best propulsion system to date, multi engine Bi-modal Nuclear Thermal Rocket (NTR) Systems with Nuclear Electric Propulsion systems? This for efficient Isp and T/W (Thrust-to-Weight) ratio coefficients favorable to shorten the amount of months in transit by maintaining and incrementally increase initial NTR generated cruise velocity to Mars along the ballistic trajectory and making minor course corrections and powering onboard life support besides maintaining artificial gravity. Thus, crews would not need to be 'hung out' in interstellar space exposed to the effects of more deep space radiation than is necessary. Of course we have the Mars 'gravity well' entry and the breaking process that also requires propulsion and fuel. Oops..! Again. What happens if this single tether were to snap and break the link; where would the crew of Hab stand lost in space enroute? Oops..! About that 100kW reactor? What happens if it tipped over driving out to sight or micro meteor strike or a single or multiple pipelines freeze up preventing flow or if there were quality production issues. The rocket fuel was less than expected and crew returning on its ERV didn't burn for efficient thrust (Non-uniform gas composition operation at non-optimum nozzle expansion area ratio can reduce thrust and specific impulse) making it hard to get off the Mars surface. To date no rocket engine has lifted off of Mars in order to throw a spacecraft of any serious mass let alone humans and their life support equipment on a return trajectory toward Earth; not to say this not achievable. Where would this leave our lost crew on the return leg to Earth? Most importantly, where would this leave the Public if after one Mars preparatory mission were to fail and the astronauts having trained and prepared not to mention the Public prepared to see our astronauts make it to Mars and return; never get off the ground due to the aborted preparatory Mars mission?
  The best approach is to test and mission Mars propellant manufacture and chemical propulsion dynamics to efficiently lift off of the Mars surface at a robotic small scale; no doubt at future Mars NASA mission. As a caveat I like the idea of the reactor system for chemical material and fuel processing, but only when humans were there to intervene if an anomaly presented itself to fix the system as a backup propellant. I believe a first mission be 100% self-sufficient, it should be the law. This was true with Apollo and should be true for Mars. Orbit equipment making it possible to rendezvous along a Mars ballistic trajectory if necessary for added measure after all Mars is at a gross minimum distance 54x10⁶km from earth, maximum distance from earth 401.3x10⁶km. Credit Stan Borowski and company at NASA Glenn Research Center, Cleveland, Ohio with a realistic plan entitled: Bimodal Nuclear Thermal Rocket (NTR) Propulsion for Power Rich, Artificial Gravity Human Exploration Missions to Mars presented at the 52nd International Astronautical Congress in 2001, Toulouse, France.

This is a more realistic approach to insure a safe and efficient round trip to Mars for humans.

HEAVY LIFT AT THE LAUNCH PAD

 In order to effectively service these larger future missions they are contingent on heavy lift capacity boosters, without larger capacity at the launch pad numerous launches would be required to lift prerequisite tonnage to orbit. One suggestion offered by Becky Farr, NASA "Heavy Lift Lady" at Emerging Technologies Team, Propulsion and Fluid Systems Test Division, Marshall Space Flight Center is to convince readers that as everyone knows STS Shuttle and derivative combos have fantastic lift capabilities modular STS element re-use concept makes good business sense too.

A quick excerpt from her paper, "Spiral Development of a Lunar Heavy Lift Launch Vehicle System."
 

HOW DOES A SPACE AGENCY BEGIN A SUCCESSFUL SPACE NUCLEAR FISSION PROGRAM...again?

The obvious answer is to actually mission and fly a space reactor for space exploration.

As it says on the Nuclear Space Course 101 lecture blackboard: Why use fission reactors in space?
Because 1kg of U235 contains 500,000 times the energy released by the decay of 1kg of Pu238 over a 10 year period. [more info]

If you like imagery, imagine a Coke can filled to the brim with U02 (uranium dioxide) then imagine the Shuttle external tank placed beside it the energy contained in Shuttle tank still would fall short fifty times; short of the energy contained in the small U02 Coke can. [more info]

 Far be it from me to tell the DOE-NR/NASA how to begin evaluation of a first future space reactor dedicated to peaceful space science and exploration.

 I don't much 'cotton' to fancy glossy brochures that NASA Headquarters endows its Directorates to peddle to the Public. I'm the type that don't much care what a perfume bottle looks like as much as what the perfume smells like to make a good gift for someone. Terms like "Corporate Focus", "Focused, Prioritized Requirements", "Spiral Transformations", "Management Rigor". These are four overarching principles that according to this new Explorations Systems Mission Directorate (ESMD) which recently has decided to defer indefinitely previously planned FY2005 Broad Agency Announcement (BAA) for the Exploration Systems Research and Technology (ESRT) and Human Systems Research and Technology (HSRT) programs. Before any technology investments get started, ESMD is suppose to reassess the technology requirements to ensure they remain properly aligned with the "Vision" for Space Exploration.

 It begs the question did NASA management in its halcyon days of human exploration of space and Moon go through these elaborate presentations? Why so much energy is spent on thrashing managerial ethos and less on actual R&D and deployment of systems? See: [Exploration NASA]

I happen to run across an abstract entitled: "Technical Bases to Aid in the Decision of Conducting Full Power Ground Nuclear Tests for Space Fission Reactors" in my readings this reads more eloquent and led toward common sense engineering as proper steps in conducting full power ground nuclear tests for space fission reactors all done without the fancy glossy printed material.
It asks these questions related to obvious benefits of full power ground nuclear testing; obtaining systems and integrated reliability data on a full-scale, complete end-to-end system this comes at some programmatic risk.
It has been a point of contention in the industry for years.

• Do the benefits outweigh the risks?
• Are there equivalent alternatives?
• Can a test facility be constructed (or modified) in a reasonable amount of time?
• Is the test article an accurate representation of the flight system?
• Are the cost too restrictive?

Here's a quick excerpt:

 Of course, there is plenty of legacy projects that have demonstrated space reactor systems really do work. Since the mid 1950's in the U.S. with the Rover nuclear rocket program was a huge success. The SNAP program again, a success, one with its liquid metal NaK coolant reactor actually flew ! The SP-100 reactor spent nearly ¼ of a billion (then) dollars developing a full power ground nuclear test before the program was shutdown.
Then the TOPAZ reactors developed by the Former Soviet Union. They became fashionable in the early 1990's when the U.S. purchased several TOPAZ II reactor thermionic systems. These were given extensive nonnuclear tests aimed at understanding the capabilities and limitations of these already successful space mission proven reactors, but since the end of the SNAP program no full power nuclear tests have been conducted in the U.S. for almost 30 years! Each of these programs is well documented online if one cares to perform a Google search. Historically fuels of spontaneously fission nuclides other than Pu238 for RTG'S include U235. One wonders why after so much success of both radioisotope space power systems and fission power systems the U.S. and NASA have not taken the initiative in publicly demonstrating the longevity in safe and efficient use in space of fission space reactor systems?

Other than criticism from the typical, prone to exaggeration claims of anti-nuclear arguments. It must be myopic politics that clouds judgment to allow these programs to flounder.

As noted in James Dewar's book, "To The End Of The Solar System" lessons to consider in keeping political 'double standards' and lack of leadership and commitment in high places down to a minimum symptoms that tend to kill projects.

Lessons for Government Program Managers:

• Find a champion in Congress, preferably a powerful one or create one.
• Expect the unexpected. The political and technical meet in you; be prepared for challenges from all directions, particularly as your budget increases. This includes foreign events, death, illness and even earthquakes.
• Issue contracts by the book.
• Be loyal to your agency leaders.
• Be open to new ideas.
• Frequently conduct comprehensive reviews on doing more with less.
• Avoid over optimism and pell-mell rushes for missions.
• Be vigilant of White House or "independent" reviews. Often they signify grave doubt at higher levels of the government and often serve only to justify the preexisting views of opponents. If they occur, make sure the reviewers visit the facilities and personnel conducting the work.
• Beware of numbers. Be quick to respond to irresponsible or politically motivated use of numbers.
• Invite your department heads, executive branch leaders, Congress, the media, and the public to tests if appropriate.
• Develop the ability to discuss your program in layman's English or do not be hesitant to use someone who can.

Lessons for the Public on Government R & D Programs.

• Recognize that government program managers are reasonably honest and dedicated civil servants, scientists, engineers, or military officers. Give their statements the benefit of the doubt.
• Question the criticism of those in the political arena who oppose a program, particularly if they make outlandish, emotional statements or raise large budget numbers. They maybe only trying to advance their own agenda.
• Beware of those who conclude a test was a failure. Research and Development (R&D) is a process in which failures occur, but nonetheless advance the state of knowledge and experience which lead to success.
• Examine requirements arguments closely. Sometimes they are appropriate, but all to often critics use them to hamper programs they dislike.
• Discount any attempt to justify a program based on its "Spin-Offs." When this occurs, it implies the program is in trouble and is seeking any argument to justify its existence. Critics tend to use it against the project as the project is grasping at 'straws' to stay alive.

 In effect there are plenty of systems whether you talk about solid core, gas core, open or close loop or bi-modal, gas cooled, liquid cooled, liquid metal cooled, heat pipe in any UC, UO2, UN or UF fuel dynamic there are a number of worthy candidates for both low thrust NEP and high thrust NTR architectures for the DOE-NR/NASA to chose from with legacy data built in. So what does the DOE-NR/NASA actually do that is any different than the countless industry participants and previous years of accumulative operational and test data haven't shown already?
No one doubts the DOE-NR/NASA's ability to conduct development, testability, transportation, storage, safety and security of enriched nuclear fueled fission space reactors. It's only why after so much previous work, the prevailing idea could be to begin again as though this technology is somehow without legacy?

How long does the government expect to 'sandbag' the issue of mounting a sustained space nuclear program?

Recent Testing on candidate space reactor systems.

For the past few years , NASA Marshal Space Flight Center developed a facility to enable testing of reactor systems without the use of nuclear fuel. Electrical resistance heaters used in the Early Fission Flight Test Facility (EFF-TF) simulate the thermal heat generated from nuclear fission. Thermal simulators have been developed over the past 5 years that would enable high realistic non-nuclear testing of systems currently under consideration, and eliminate lifetime and reliability concerns that were encountered with the electrical heaters of the SNAP 10A program. Successful tests have been conducted in the facility on components and at the integrated subsystem level.
Direct Drive Gas Cooled Reactor Core has been fabricated and initial testing of a core segment completed at the EFF-TF. The same for Heat Pipe Reactor and for work associated with pumped alkali metal systems has been initiated.

Testing Options:

• Full power ground nuclear test. Testing of a complete reactor system where heat is generated by fission in a prototypic flight system.
• Zero power nuclear tests. Neutronic testing of various operational characteristics of a fission reactor, where the testing may include prolonged operations at steady-state or transient thermal conditions yet leaves the reactor and components essentially non-radioactive. In other words self-sustaining fission chain reaction is maintained at a low power level to preclude generation of significant fission products.
• Nonnuclear tests. Testing using electrical heaters to simulate the heat from fission reaction.

Full power nuclear test:

Advantage: Testing is performed on complete end-to-end system. Increased confidence in performance of a flight system. Design temperature and full power can be ascertained.
Disadvantage: Test article might not represent the fight system because of the additional facility & safety requirements. Components may not be analyzed until test is fully complete, this could lead to delays in modifications and optimization. The Use of Radiation-resistant instrumentation potentially limiting the amount of data that could be obtained replacement of failed instruments would require efficient remote human and or robotics operations. Over-testing or testing-to-failure may not be feasible. No operational facility where these test can be performed would have to be created. Valuable fresh fuel would become irradiated and might not be good for a flight system. Licensing of new or modified facility may take months if not years to certify. Does not provide safety data, only (potentially) related to reliability.

Nonnuclear system test:

Advantage: testing performed on subsystems and complete system without fuel. Since no radiation is generated, test articles maybe modified or swapped out easily and timely. Test duration could be long or short as needed. Failure causality can be quickly identified and corrected. Extensive temperature, pressure, strain and bulk deformation measurements to (aid in predictive reactivity feedback) can be made. Allows flex in testing to include margin and test-to-failure. Expense and schedule impacts are reduced from facility and environment. Provides potential reliability and safety data. Large vacuum chambers facilities exist for nonnuclear tests.
Disadvantage: Radiation damage to components not evaluated. Control system not tested. Nuclear design not verified. Ensure thermal simulators do not contaminate the flight unit.

Zero power nuclear test:

Zero power critical experiments can be performed in a range of temperatures and with various temperature profiles to obtain data on reactivity coefficients and reactor behavior during various steady-state and transient conditions. Electrical induction heaters can be used to simulate operating temperatures while the reactor power output is maintained at extremely low levels, thus eliminating the generation of fission product inventory. Licensed operational facilities exist within the DOE/NNSA Complex where these type tests could be performed.
Advantage: Reactivity feedback effect without irradiation of system being tested and platform. Neutronic performance can be demonstrated at low power. Valuable fresh fuel would not become irradiated and used at flight time. Performance of closed loop digital control system can be tested and optimized in non-irradiated state.
Disadvantage: Tests in these experiments can't be conducted at full power. Only postulated anomalous conditions can be tested - not real. Modifications to the test unit might be required to satisfy facility requirements.

Costs: Reactor development costs have been traditionally very large.

• Rover program estimated at $1.4 billion (period dollar value).
• SNAP Reactor Program spent over $880 million (period dollar value).
• SP-100 spent over $400 million in 1980 dollars.
• The then Soviet Union spent the equivalent of $1 billion U.S. (period dollar value) in development of the Topaz systems.

Resent estimates for future space reactor full power ground nuclear tests including test unit approximately:
$1 billion. Resent electrically heated tests excluding test unit approximately: 2-4 million dollars. Zero-power critical tests are at the same, approximately 2-4 million dollar range.

Full power ground nuclear testing or combinations of nuclear and non-nuclear tests are options that can provide the sponsor with the level of certainty that the system under development will perform as designed. A lot has been learned and technology gained from past experience and it would be wise when building a new space nuclear reactor to incorporate where technically and fiscally appropriate since these tests cost the taxpayer.

Other systems for consideration:

Solid Fuel, Dynamic Power Conversion Concepts (Liquid Metal Cooled)

• 10 MWe Nuclear Rankine System; Fuel:Uranium Nitride,Primary coolant: lithium, reactor outlet temperature:1650K, PC: Closed Rankine Cycle, Specific Mass:7kg/kw at 10 MWe.
• Potassium Rankine System; Fuel: UN-W/25 Re Cermet, Primary coolant: Lithium,Reactor outlet temperature:1550K, PC: Potassium Rankine Cycle, Specific Mass: 3kg/kWe at 10 MWe.
• RMBLR [Rotating Multi-Megawatt Boiling Liquid-Metal Reactor] "Rambler" System; Fuel: Blocks with coolant channels UN+Moly alloy with Rhenium & hafnium, Primary coolant : Potassium, Reactor outlet temperature:1440K, power conversion: Direct Rankine, Specific Mass: 1-2kg/kWe @ 20 MWe assuming a bubble membrane radiator.

Solid Fuel, Dynamic Power Conversion Concepts (Gas Cooled)

• ENABLER; Fuel:UC bead coated with ZrC, Primary Coolant : Helium-Xenon gas, Reactor Outlet Temperature:1920K, PC: Closed Brayton Cycle, Specific Mass: ~3 kg/kWe@10MWe.
• NEPTUNE w/MHD ;Fuel UC2/C rods. Primary coolant: Hydrogen, Reactor Outlet Temperature:~1900K, PC: MHD)
• PARTICLE BED; Fuel: 0.05cm particles of UC2 in porous PyC and SiC-or-ZrC, primary coolant:He-Xe,Reactor Outlet Temperature:1100-2000K, PC: Closed Brayton Cycle, Specific Mass: 4kg/kW at 10 Mwe.
• PELLET BED; Fuel: 1.0cm pellets of graphite imbedded with UC/ZrC particles, primary coolant: Hydrogen, reactor outlet Temperature: 1800K, PC: Potassium Rankine or Helium Brayton cycles, specific Mass: ~6.4kg/kWe@10MWe.

Vaporized Fuel Concept

• VAPOR CORE REACTOR with MHD; Fuel:UF4 vapor, Working Fluid: alkali metal Fluoride,Reactor outlet Temperature: 4000K, PC: Closed Rankine Cycle, Specific Mass: 3-8kg/kWe@10-70MWe for a burst power system.

In conclusion, at the end of the day merit in space exploration is bringing projects to closure by flying space nuclear missions, with commitment and maintaining a well informed Public over projects in fission space reactors systems. Without building on these successes other important nuclear space power systems such as Fusion and Antimatter and as yet unknown advanced power systems will remain just a test bed of data never meant to service missions in space exploration.

I've made note of my approval in the latest round of Government policy in this regard. [See: Florida Today]

I like most have to wait and see if the Government (DOE-NR/NASA) really are committed to fly a space nuclear fission reactor system within the remainder of this decade. If the U.S. won't fly a space reactor some other country looking for preeminence in space technology will.

Just like the sea water on the shoreline relentless to claim its natural path against the shore. So does the Human desire to see over the horizon.

Sources:

Technical Bases to Aid in the Decision of Conducting Full Power Ground Nuclear Tests for Space Fission Reactors; Laurie L. Hixson, Michael G. Houts, and Steven D. Clement. STAIF 2004 edited by M.S. EI-Genk.

Spiral Development of a Lunar Heavy Lift Launch Vehicle System Rebecca; A. Farr, NASA Marshall Space Flight Center, Engineering Directorate Test Laboratory, Propulsion and Fluid Systems Test Division, ET11, Huntsville, AL 35812, David L. Christensen, Madison, AL (retired.) Edward L. Keith, La Verne, CA (retired.) 2005.

TO THE END OF THE SOLAR SYSTEM, James A. Dewar , Appendix G, The University of Kentucky Press, 2004.

credit © Mark Wade, astronautix.com