DESIGN AND OPERATION OF 1800 F PUMPED BOILING RUBIDIUM LOOP SYSTEM AND DETERMINATION OF DENSITY AND VAPOR PRESSURE RUBIDIUM BETWEEN 174 AND 1800 F. Space Power Systems Technology Studies: Rubidium, Corrosion and Physical Properties Evaluation Program. Final Report (Report No. 16), February 1, 1960 through May 31, 1961

Technical Report · Wed Oct 31 00:00:00 EST 1962

DOI:https://doi.org/10.2172/4784306· OSTI ID:4784306

A pumped boiling rubidium loop was designed, operated, and analyzed. The loop simulated some of the characteristics of a boiling rubidium space power conversion system. Such a system would involve either a reactor or heat exchanger as the power source, and a turbine and radiator as the power conversion and vapor condensing equipment. This loop was used to study instrumentation and control problems and effects of rubidium corrosion on containment materials, and to gain some rough physical property and heat transfer data on rubidium. The first loop operated with 316 stainless steels and was run for l72 hours at various temperatures, the maximum being 1550 deg F boiling. The 316 stainless steel loop was operated only a short period since it was intended as a system shakedown measure. The second loop was Nb-l Zr loop alloy operated for 455 hours total at l840 deg F and a vapor quality of 9%. ln the latter loop, the last 335 hours of operation were continuous. Stable boiling at this vapor quality level was achieved withont the use of special liquid vapor phase separaration devices. Operation of the loop was stable in all phases; however, overheating of the environmental chamber was observed due to insufficient insulation on the loop end resultant high heat losses from the loop heater and boiler. The niobium loop run was terminated by a cracked weld at the entrance to the condenser section in the hot portion of the loop/su Negligible corrosion by the rubidium on both loops was observed. Some carbide penetration on the outside of the niobium loop was observed which apparently was caused by carbonaceous impurities in the argon gas. The failure of the weld at the entrance to the condenser was believed to be caused by carbide penetration effects. The protective coating of zirconium foil wrapped around - the niobium loop was observed to fulfill its function and to be entirely necessary to insure the long life operation of the niobium loop. However, some alloying of this foil with the niobium occurred at the hottest portions of the loop. Improved and refined existing metallographic techniques were developed for the evaluation of refractory metal corrosion. Results showed corrosion of refractory containment materials by rubidium is not critical in this temperature range. Rather, the critical corrosion occurs from the contaminants in protective and environmental atmospheres. Preliminary boiling refluxing tensile tests utilizing 316 stainless steel and Nb-l Zr alloy were operated for short times up to 1800 deg F/su Negligible corrosion was observed. Longer time and more closely controlled tests are necessary to fully determine what the corrosion effect of rubidium of 316 stainless steel and Nb-l Zr alloy is for this temperature range. The density of rubidium was measured between 174 and 1307 deg F by an expansion method. The height of the rubidium in an enclosed tube was measured by electrodes which shorted out as the column of rubidium rose. The data conforms within plus or minus 0.01 grams/cm to the equation: B = 1.5005 -2.62 x 10/sup -4 t + 3.94 x 10/sup -8/ t/sup 2/. The total vapor pressure of rubidium was measured between l000 and 1800 deg F by measuring the pressure of a sealed capsule. The data conform to the following equation within plus or minus 2% or plus or minus 0/su2 psi, whichever is higher over the range from 1000 to l800 deg F. The equation is as follows: log/sub 10/P = (-46S8/T) - 1.758 log/sub 10/T + 10.185 (Pressure in psia and temperatures in deg K)/su This equation gives the boiling point of 1244 deg F/su In the same apparatus used to measure vapor pressure an attempt was made to measure the latent heat of vaporization by a direct method at different temperatures. The design of the apparatus was basncally correct, but an error in instrumentation installation prevented measurement of the actual boiling and condensing rates inside the apparatus. Modifications of the apparatus to enable the direct measurement of latent heat of vaporization are being made. (auth)

• Research Organization: Aerojet-General Nucleonics, San Ramon, Claif.
• DOE Contract Number: AT(04-3)-251
• NSA Number: NSA-16-014834
• OSTI ID: 4784306
• Report Number(s): AGN-8034
• Resource Relation: Other Information: Orig. Receipt Date: 31-DEC-62
• Country of Publication: United States
• Language: English

Related Subjects

ENGINEERING AND EQUIPMENT
ARGON
BOILING
COATING
CONDENSERS
CONTROL
CONVERSION
CORROSION
DENSITY
EFFICIENCY
ELECTRODES
ERRORS
FOILS
GASES
HEAT EXCHANGERS
HEAT TRANSFER
INSTRUMENTS
MATERIALS TESTING
MEASURED VALUES
METALLOGRAPHY
METALS
NIOBIUM
NIOBIUM ALLOYS
PERFORMANCE
PLANNING
POWER
PRESSURE
QUANTITATIVE ANALYSIS
REACTORS
REFRACTORIES
RUBIDIUM
STAINLESS STEELS
TEMPERATURE
TESTING
THERMAL INSULATION
TUBES
TURBINES
VAPORS
VESSELS
ZIRCONIUM ALLOYS
NESDPS Office of Nuclear Energy Space and Defense Power Systems