Assemblies and Research Reactors

Each core investigated was surrounded by a blanket at least 12 inches thick which consisted of 83.32 U-238 and 7.32 stainless steel. The assumed density of carbon in the core was 2.25. The fission ratios and reactivity coefficients for die first case listed in the table were determined at the center of a core having the same composition as listed, but with a low density inner blanket. 

Prior to the performance of sudi experiments cakulations are done to determine die general properties of such assemblies. These inchide unrealistic estimate of the expected critical con lition. The optimum rylindrical cores, those With mininium critical mass requirements.fm a given composition satisfy the idationship 0.8 L/D 1 where L is the core height and D is the core diameter. 

Calculations were made primarily in spherical geometry using the S method. These results were dien interpreted to cylindrical geometry using reasonable shape factors based on both calculation and experiment. The shape factor (S.F.) is defined as the ratio of the critical mass of a spherical core to that of a cylindrical one. Bodi cores have the same composition and similar reflector parameters. For many sudi systems a shape factor such that S.F. = 0.95 0.01 appean to be reasonable in the L/D range of interest. 

Using the same method of calculations, the critical loading of the cold clean TREAT reactor, without its slots, was evaluated. 

CONDENSED DATA OF LOS ALAMOS CRITICAL ASSEMBLIES (Chiphite CS-312 Grade, d = 1.67) 

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TNA PRO AB 6/2305. Zero energy reactor HECTOR. See also TNA PRO AB 17/100. HECTOR. Hot Enriched Carbon-moderated Thermal Oscillator Reactor. TNA PRO POWE 74/83. Rebuilding of Jason at Royal Naval College, Greenwich fire near Hawker Siddeley reactor building, Langley, 22 May 1961 safe operation of critical assemblies and research reactors. 

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