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NERVA Program. Four reactor test series to demonstrate Basic nuclear technologyKIWIPhoebus Pewee-1 Nuclear Furnace-1 KIWI, Phoebus, and Pewee-1; open cycle systems and exhausted their effluent into the atmosphere Nuclear Furnace-1 used an effluent treatment systemBetween 1959 and 19
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1. Testing Options for Nuclear Thermal Propulsion Systems
2. NERVA Program Four reactor test series to demonstrate Basic nuclear technology
KIWI
Phoebus
Pewee-1
Nuclear Furnace-1
KIWI, Phoebus, and Pewee-1; open cycle systems and exhausted their effluent into the atmosphere
Nuclear Furnace-1 used an effluent treatment system
Between 1959 and 1972, the Space Nuclear Propulsion Office oversaw 23 reactor tests
3. Why Build a Nuclear Rocket? Three times the ISP of chemical engines
its have been shown to be:
Faster
Reduced Transit times for long stay missions
Reduced round trip times for short stay missions for the same initial mass to low earth orbit (IMLEO)
Cheaper
Reduced IMLEO requirements for the same mission duration
Greater mission flexibility for VSE Mars (cargo and especially piloted) missions with respect to departure windows
Fewer launches required
Fewer supplies, equipment, power needed
Better
One propulsion system capable providing a step change capability in meeting many exploration mission needs
Technology within developmental timeframe
Reduced exposure for manned missions
4. Basic Options Ground test with the US
Ground test remotely (i.e. in an ocean)
No ground test
5. Elements of a Ground Test Facility Facilities
Containment Building
Control Building
Test Cell
Exhaust Treatment System
Hydrogen Supply System
Cold Engine Assembly Building
Hot Engine Disassembly Building
other support systems and buildings
Dependent on size (thrust), thermal power level and duration
NTR engine physical size modestly affects size of containment building
6. Test Facility Concepts Above Ground Effluent Treatment System (ETS)
Subsurface Active Filtration of Exhaust (SAFE) Test Facility
Other?
7. Effluent Treatment Systems Needs Cooling the hydrogen effluent
Removing particles from the gas flow stream
Further reduction of the temperature
Removing the water and dissolved fission products
Removing the noble gases
Flaring the exiting hydrogen stream (containing no detectable fission products)
8. SNTP Effluent Treatment Systemfor 550 MWt
9. Parametric Estimation of ETS Costs
10. Subsurface Active Filtration of Exhaust (SAFE) Test Facility Filtration of the engine exhaust using the NTS alluvium soil / rock as the holdup and active filtration medium
relies upon the alluvial soil characteristics to filter the effluents from the NTR exhaust
Nozzle exit is sealed at the surface
Exhaust pressure will drive exhaust and water vapor into the porous soil or rock at a rate equal to the NTR mass flow
Could be operated for long periods over a wide range of engine thrust levels
11. SAFE Facility Description Uses a borehole 8 feet in diameter by 1200 feet deep
Upper 100 feet would be steel encased
Cooling water would be sprayed into the borehole to limit the exhaust temperature
Maximum back pressure buildup in the borehole would be 36 psi
Independent study by the Desert Research Institute (DRI): Some radionuclides would reach the surface within several years after injection but, at acceptably allowable levels for the NTS
12. Comparison between ETS and SAFE ETS
Pros:
No large quantity of contaminated liquid effluent will be generated.
Altitude simulation may be possible with this system.
A center for ground testing with dedicated test facilities could be established for NTP systems up to the design rating.
Performance of the system will be well characterized after initial testing.
Cons:
Large quantities of liquid hydrogen will be required for each test.
Large, complex effluent filtration systems have not yet been demonstrated.
Public acceptance of once through exhaust treatment with discharge to the atmosphere may be challenging.
Containment isolation system during abnormal events may be complex.
13. Comparison between ETS and SAFE SAFE
Pros:
No active effluent treatment system required.
Existing boreholes are available.
Less hydrogen will be required per test.
Potential for significant costs savings
Cons:
Further studies could show the need for waste coolant water removal and a filtration system.
Boreholes may have limited reuse capability and require relocation of certain GTF assets, (e.g., portable containment structure).
Monitoring of borehole alluvial soil performance during and after testing will be required.
14. Next Steps Fuel Development - driving force for the design of the effluent treatment system will be the integrity of the fuel under normal operating and abnormal operating conditions. Limited information available as to how much of the halogen or noble gases can be retained in the fuel (needed for both ETS and SAFE)
Demonstration of Subsurface Filtration System - a subscale proof of concept test is needed
Gas would be spiked with Krypton-85 to permit monitoring of the gas permeation in the alluvial soils
ambient and elevated temperature tests could be performed