Patent Number: 042467519
Section: description

More specifically, in FIG. 4 there is shown a nuclear rocket 10 having a prior art hydrogen propellant nuclear engine and exhaust nozzle arrangement 12 (see also FIG. 3). For reasons previously indicated, nozzle 14 of the arrangement 12 is of the convergent-divergent type as indicated by reference characters 16 and 18, respectively. The engine and nozzle arrangement 12 is also provided with a plurality of elongated propellant energizing or fissile fuel bearing modules arranged in a cluster so as to form a nuclear reactive region 20 which generates heat energy for transfer to the employed propellant such as hydrogen. The modules are each normally formed from a high temperature capacity and neutron moderating material such as graphite, a carbide or a refractory metal with fissile fuel such as enriched uranium disposed therein and with coolant-propellant channels provided longitudinally therethrough. Further, the modules are interfitted and supported in cluster form by any suitable means such as a barrle or hung from or supported on a plate like structure (not shown). The latter support means or barrel can then be supported relative to a pressure vessel 22 (FIG. 4). The exhaust nozzle 14 is supported adjacent propellant exit ends 24 of the clustered modules or reactive region 20 so that the total propellant flow is directed therethrough. Thus, as already considered, nozzle throat section 26 is subjected to extremely high temperature conditions which lead to material and heat removal problems which in some applications are irresolvable or solvable only through undesired and sometimes unreliable complexity and great exposure. In FIGS. 1 and 2 there is shown a nuclear engine and nozzle arrangement 30 constructed in accordance with the principles of the invention so as to avoid the difficulties associated with known prior art structure. The arrangement 30 comprises a cluster 32 (reactive region) of supported fissile fuel bearing and elongated modules 34 (FIG. 6) or 36 (FIG. 8). The base material of the modules 34 and 36 is preferably selected from the group of materials already discussed in connection with FIG. 3, and similarly a fissile fuel such as enriched uranium can be disposed therein. Thus, the elongated module 34 can be formed from graphite or other high temperature capacity and neutron moderating material and is provided with a plurality of longitudinally extending channels 38. Fissile fuel is disposed in the modules 34 by means of respective elongated fuel rods 40 supported in the module channels 38. Each fuel rod 40 is also provided with longitudinally extending channels 42 through which coolant-propellant such as hydrogen flows longitudinally for heating therefor and subsequent discharge from the engine and nozzle arrangement 30. Further, each fuel rod 40 can be formed from the group of materials already discussed in connection with FIG. 3 containing a fissile material such as enriched uranium. In this case, a convergent-divergent nozzle structure 44 is formed integrally with the propellant exit end of the module 34 and as such accepts and channels outwardly the heated propellant discharged thereto from the fuel rod channels 42. As noted previously, the purpose of the nozzle structure 44 is to develop supersonic velocity in the outgoing propellant. The elongated module 36 (FIGS. 7 and 8) is similar to the module 34 except that the base material (such as graphite) of module body 46 has incorporated interstitially therein fissile fuel such as enriched uranium and further is provided with longitudinally extending coolant-propellant channels 48. In this case, a nozzle structure 50 is also disposed adjacent the propellant exit end of the module 36 but is a separate element preferably of the same material as the unfueled base material of the module body 46 secured to the latter by suitable fastener means such as thread means 52. Through such use of non-fueled structural material, nuclear reactivity is avoided in the nozzle structure 36. When the modules 34 or the modules 36 are respectively clustered together to form the reactivity region 32, the individual nozzle structures 44 or 50 are also clustered together (see, for example the nozzle structures 44 in FIG. 1) so as to provide a plurality of velocity development flow paths 54 for the propellant or hydrogen as it is exhausted from the modules 34 or 36. Although the propellant in the individual flow streams will have thus acquired supersonic velocity, it can often be desirable to develop additional propellant velocity without lengthening the individual module nozzle structure 44 or 50. Thus, in nuclear or other rockets, a single diverging nozzle or skirt 56 can be secured in place by suitable means adjacent the exit ends of the nozzle structures 44 or 50. The skirt 56 then accepts the total propellant for further velocity development and finally for thrust producing discharge through skirt open end 58. The foregoing description has been set forth only for the purpose of illustrating the invention. Accordingly, it is desired that the invention be not limited by the embodiments described, but, rather, that be accorded an interpretation consistent with the spirit and scope of its broad principles.