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Description: The hazards evaluation was modified to reflect certain changes made to the equipment as a result of operating experience. These changes included: the addition of a startup interlock circuit; the modification of a startup interlock circuit; several minor modifications to the control rod actuators; and the addition of the tube-sheet cooling system. (M.C.G.)
Date: May 1, 1960
Partner: UNT Libraries Government Documents Department


Description: The GCRE-I hazard summary report is supplemented in the following areas: geometry and operation of the steam cooling system, the reactor coolant by-pass, and by-pass valving; the means by which by-passed circuits are prevented from remaining unintentionally disabled; design details, and details of procedure for core flooding operations. (A.C.)
Date: March 1, 1959
Partner: UNT Libraries Government Documents Department


Description: Further engineering and physics data to aid in constructing GCRE-1 were obtained in critical-assembly studies. Four major experiments were performed to investigate the effect on reactivity caused by changes in axial reflector materials, the effect on reactivity and the power perturbation caused by fast safety control-blade guides, the effect of changes in fuel-element material composition, and the effect of changes in fuel-element spacing designed to produce uniform radial power-generation rates. All studies were performed with a 4-in.-thick lead reflector at the core perimeter. Axial-reflector-material studies employed combirations of aluminum and steel reflectors. The reactivity worth of a 2 3/4-in.-thick steel reflector was +0.414% DELTA k/k compared with 0.175% DELTA k/k for a similar aluminum reflector. The perturbation in the flux distribution caused by the safety-blade guides was localized, and affected only the regions immediately adjacent to the guides. The combined reactivity worth of two guides was -0.281% DELTA k/k. Fuel-element material compositions were changed by separate additions of fuel and stainless steel. An increase in uranium loading from an average value of 303 to 404 g per element would provide, based on extrapolations from experimental data, a reactivity of about 4.5% DELTA k/k. An increase in steel from 1708 to 2093 g per element decreased the core reactivity by abeut 1.1% DELTA k/k. A change in fuelelement spacing reduced the ratio of maximum to average power generation from 1.46 to 1.24. (auth)
Date: December 29, 1958
Creator: Dingee, D.A.; Ballowe, W.C.; Egen, R.A.; Jankowski, F.J. & Chastain, J.W. Jr.
Partner: UNT Libraries Government Documents Department


Description: In research in support of the GCRE, procedures for the fabrication of stainless steel-clad flat-plate fuel elements having a core of 28 w/o UN dispersed in an iron-18 w/o chromium--14 w/o nickel--2.5 w/o molybdenum matrix were developed. The preparation of UN and its compatibility with the components of the matrix alloy were studied. The UN for the program was prepared by nitriding uranium metal at 850 C and then dissociating the U/sub 2/N/sub 3/ produced to UN in a vacuum at 1300 C. In compatibility studies, UN reacted with nickel alone at 1800 F, but no reaction with nickel was observed when the other matrix components were also present. The effects of fabricational variables were evaluated by metallographic examination, longitudinal and transverse tensile tests, bend tests, and corrosion tests. Studies indicated that minus 200 plus 325-mesh UN dispersed in a minus 325-mesh elemental-powder matrix rolled green vith a 30 per cent initial reduction at 2100 F and then annealed 3 hr at 2300 F produced the best fuel core. (auth)
Date: July 31, 1959
Creator: Paprocki, S.J.; Keller, D.L.; Cunningham, G.W. & Foulds, A.K. Jr.
Partner: UNT Libraries Government Documents Department


Description: Investigatiors were made of various materials for development of metal- canned and semi-homogeneous GCRE-II fuel element concepts. The materials were studied for application to development of fuels, grapanite, silicon-silicon carbide coatings, metal claddings, carburization barrier coatings, and graphite joining. A survey of the literature showad that uranium carbide fuels are superior to other types for the applications described and that refractory metal or metal carbide fuel coatings appear superior to other types for use with the types of graphite investigated. Experimental measurements were made of the thermal conductivity, tensile strength, stress-strain reiationships, and thermal expansion of graphite powdsr bonded with baked carbon at a final firing temperature of 760 deg C. Results showed that these materials were stronger and more isotropic at all test temperatures than a standard structure graphite such as ATJ. The thermal conductivity is somewhat lower and the thermal extansion slightly higher than the corresponding properties of ATJ. A silicon-silicon carbide coating was developed as an osidation-resistant coating for graphite. Preliminary air oxidation tests at 1000 deg C showed that the first samples survived 2000 hr with 10% failure. Subsequent experiments showed that it is reasonable to expect better performance in further tests. Tests for compatibility with graphite were conducted on zirconium, Zircaloy-2, "A" nickel, and K-Monel at 1750 and 1850 deg F for 1000 and 1500 hr. Chemical analyses, metallography, and tensile tests indicated that the K-Monel is the material most compatible with graphite; it possesses good strength and ductility with negligible carburization or carbon diffusion. Zircaloy-2 tubing showed a growth of from 3.4 to 3.8% when thermal cycled 100 times between 850 and 1850 deg F. Tests for compatibility with Hastelloy X were conducted on graphite samples coated with molybdenum, niobium carbide, and zirconium carbide at 1750 deg F and 300 psi for 1000 and ...
Date: December 30, 1960
Creator: Carpenter, R. & Del Grosso, A.
Partner: UNT Libraries Government Documents Department