Patent Number: 043702988
Section: summary

The present invention resides in a breeder reactor system for producing thermal energy and valuable isotopes by exploding a plurality of sub-critical masses of fissile and fertile actinide slugs within an ellipsoidal pressure vessel. A molten metal working fluid is injected into the vessel prior to the explosion and the heated working fluid is thereafter drained from the vessel for use in generating electric power or for pumping. Various proposals have been made for exploding pellets of a nuclear fuel within an explosion containing vessel and in which the fuel is ignited by means of an intense laser pulse. One type of thermo-nuclear fusion reactor has been described in U.S. Pat. No. 3,624,239, issued to Arthur P. Fraas on Nov. 30, 1971. In this type of reactor pellets of frozen thermo-nuclear fuel of Deuterium-Tritium are periodically and singly injected into a central void of a body of liquid lithium which is circulated in a pressure vessel. Each pellet is bombarded with an intense laser pulse to produce a fusion reaction, thereby heating the lithium. The heated lithium is then conveyed to a heat exchanger and tritium recovery system after which the lithium is conveyed back to the pressure vessel. Another proposal for laser ignition of a pellet of Deuterium-Tritium in a pressure vessel is disclosed in U.S. Pat. No. 3,762,992, issued on Oct. 2, 1973 to Hedstrom. In this laser driven fusion reactor, a thick blanket containing lithium is provided in the pressure vessel to convert the fast neutron energy from the thermo-nuclear explosion into heat and into tritium fuel. The reactor employs a solid wall to separate the reaction cavity from the lithium blanket. Protection of the reactor's "first wall" is provided by a thin layer of ablative lithium, which, as it vaporizes, absorbs the energy of radiation and impact. Additional proposals are set forth in "Transactions" of the American Nuclear Society (TANSAO 18-1-401) of June 23-27, 1974 in which the author A. D. Krubein discusses laser ignited fission-fusion micro-explosions in containment chambers. Various designs of fission-fusion blanketed explosion devices which are injected into a pressure vessel for producing thermal energy and valuable isotopes are also disclosed in Edward F. Marwick U.S. patent application Ser. No. 268,864, filed July 3, 1972; Ser. No. 284,086, filed Aug. 28, 1972; Ser. Nos. 308,978, 308,979, and 308,980, all filed on Nov. 24, 1972; Ser. No. 325,005, filed Jan. 19, 1973; and Ser. Nos. 355,015 and 355,016, both filed on Apr. 27, 1973. U.S. Application Ser. No. 268,863 more particularly, discloses the concept of exploding blanketed nuclear devices in a pressure vessel having an atmosphere of carbon dioxide. Radioactive debris produced by the explosion, including valuable isotopes, are collected at the bottom of the vessel while steam is produced outside of the chamber for the production of useful work. U.S. Application Ser. No. 308,978, more specifically, discloses a tubular shaft for photon ignition by means of a laser of a nuclear explosive device within non-transparent fluids. U.S. Application Ser. No. 308,979, more specifically, discloses a lens system for concentrating laser energy onto a nuclear explosive device. The difficulty in the construction of the various types of nuclear fission-fusion reactors thus far proposed, resides in the problem of igniting the projectiles or pellets by means of laser generated photon pulses. Calculations have shown that the critical mass of a fissionable assembly can be reduced by laser implosion techniques to such a degree that a fission micro-explosion becomes possible. However, even the largest lasers in operation today are not yet powerful enough to generate the ultra-high pressures needed to implode the pellet material into a heated plasma state to cause a fusion reaction. Thus, the sort of short-pulsed, very intense laser for generating the ultra-high temperature plasma needed to initiate "burning" of the fuel has not been developed and efforts to scale up present generation of lasers are not proceeding as rapidly as planners had hoped. The task of heating the nuclear fuel to a sufficiently high temperature at the required density so that it will begin to "burn" has proven to be much more difficult than anticipated. Once the fuel is ignited, the hot, dense, gaseous mixture of ions must be held together for a time long enough so that more energy is liberated through "burning" than is invested in the ignition process. Serious problems have also been encountered in the timing of generating a laser pulse and in the alignment of a laser such that a laser pulse will intercept a pellet at the desired position as a pellet is injected into a pressure vessel. Any timing error or misalignment in the direction of the laser pulse will thus result in the failure of obtaining "ignition" of a pellet thereby wasting great amounts of energy used in the operation of the laser and in the fabricating cost of the pellets. Accordingly, laser induced thermo-nuclear microexplosions for the economic production of thermal energy and fissile isotopes are not yet within the reach of present day technology. The present invention provides an alternative to controlled fission reactors which are in operation today as well as to the various types of fission, fusion, or fission-fusion reactors in which nuclear projectiles or pellets are ignited by laser generated photon pulses. SUMMARY OF THE INVENTION The present invention overcomes the foregoing problems in providing a reactor system capable of containing an essentially unlimited number of successive fission explosions within an ellipsoidal pressure vessel. The fission explosion is produced by propelling a pair of slugs or pellets, each containing a sub-critical mass of actinides into the vessel. The slugs intercept near the center of the vessel to produce the explosion as the combining masses become more than critical. A major portion of a working fluid is allowed to flow under gravity into the pressure vessel so that a major portion of the working fluid is concentrated in a somewhat spherical pattern around the combining slugs near the center of the vessel and without interfering with the movement of the slugs as they enter the vessel through barrel openings provided in the vessel. A minor portion of the working fluid is sprayed into the vessel to protect the barrel openings at the instant of the explosion and to cool and protect the wall of the pressure vessel. The slugs are propelled into the pressure vessel by means of reuseable accelerating mechanisms positioned externally of the vessel. The working fluid, heated by the explosion, is drained from the pressure vessel and is used to perform useful work. The debris produced by the exploding slugs, including fissile and fertile isotopes, is collected as a precipitate from the working fluid and is fabricated into additional slugs. Other isotopes such as Pu.sup.239 and Tritium produced in the reactor system are useful in other reactors. Tritium decays into He.sup.3 which is suitable as a reactor control gas in todays atomic reactors or as a fuel in fusion reactions. A neutron absorbing fluid or slurry is pumped through a passageway within the wall of the pressure vessel to provide additional protection to the integrity of the wall and to lessen fissionings near the wall. Movable closure mechanism are provided to allow access of the slugs into the pressure vessel while preventing the working fluid and other radioactive material and gases from escaping from the vessel into the slug accelerating mechanisms. Solid materials and gases are evacuated from the vessel and are separated for reuse or disposal.