RU2069899C1 - Radiation shielding for space nuclear power plant - Google Patents

Abstract

FIELD: nuclear power engineering. SUBSTANCE: radiation shielding has container in the form of shell and bottoms with tubes welded into them and passed through container, each tube containing internal can of smaller diameter. Flanges mounted at ends of tubes and cans seal annular space formed by them which is filled with lithium hydride granules. EFFECT: simplified design. 2 cl, 2 dwg

Description

 The invention relates to the field of nuclear energy for spacecraft and, in particular, to shadow radiation shields (RE) of space nuclear power plants (NPPs) designed to reduce the level of neutron radiation from a nuclear reactor to values acceptable for the payload of the spacecraft.

 A number of designs of such REs are known, using lithium hydride as a light component component (intended mainly to reduce the level of neutron radiation), filling a metal container by pouring or laying pressed blocks (radiation protection design of SNAP-10A nuclear power plants in the journal: Issues of rocket Techniques, 1965, N2 (122), pp. 3-17; design of RE in the book: Basic Theories, Designs, and Operation of Space Nuclear Power Plants (L. Energoizdat, 1987, pp. 275-276); manufacturing methods (Nuclear Engineering and Design magazine, 1974 N 26 pp. 444 460).

 The disadvantage of this design is the absence of through channels in the RE for the passage of reactor control elements. The closest technical solution to the claimed one is the radiation protection design of a space nuclear power plant containing a container in the form of a conical shell with bottoms, which are welded in through pipes and filled with lithium hydride by pouring, which forms a solid monolith after solidification (design of RE NPP in the book “Design and Strength calculation of space electric rocket engines ", Moscow Engineering. 1970, p. 83, 4th Semposium on Space Nuclear Power Systems. CONF-870102 Symms Albuquerke 1978. pp 115 - 118).

 The disadvantage of this design and its manufacturing method is the impossibility of reducing the annular gap between the element of the control system and the RE to the values necessary for radiation safety (up to 1 mm) due to significant pipe deformation (more than 3 mm) during lithium hydride crystallization.

 The task to which the claimed invention is directed, increases the resource of REs or an equivalent reduction in its mass.

 EFFECT: increased straightness of pipes intended for passage through them through RE of reactor control elements.

 This result is achieved by the fact that each pipe is provided inside with a coaxially located case of a smaller diameter and flanges that seal the end of the ring cavity formed by them, into which granular lithium hydride is placed.

 In addition, in the wall of the pipe separating the cavity of the cast lithium hydride from the granular, a connecting hole is made.

 Figure 1 and 2 shows a structural diagram of the RE in accordance with the features of the claimed invention.

 Shadow radiation protection of a space nuclear power plant (Fig. 1), containing a container in the form of a conical shell 1 with bottoms 2, 3 into which through pipes 4 are welded and filled with lithium hydride by pouring, which forms a monolith 5 after solidification.

 Each pipe 4 is equipped with a coaxially located cover 6 (figure 2) and flanges 7 and 8, sealing the ring cavity formed by them, into which granular lithium hydride 9 is placed.

 In the wall of the pipe 4, separating the cavity of the cast lithium hydride 5 from the granular 9, a connecting hole 10 is made.

 This device operates as follows.

 Upon reaching protection, the neutron flux is attenuated both by a lithium hydride monolith 5 and granular lithium hydride 9. Some of the neutrons that fall into the gap between the case 6 and the control element 11 undergoes multiple scattering due to its small size, as a result of which the neutron flux is also attenuated. At the same time, the guaranteed clearance due to the calibrated cross-section of the cover 6, ensures the normal functioning of the reactor control system.

 Thus, the proposed design of the RE allows you to have a gap between passing through the protection of the control element of the reactor and the cover no more than 1 mm for any possible deformation of the pipe, which ultimately significantly reduces the "cross" of ionizing radiation in the annular gap between the element of the control system and protection. As a result, for a given maximum permissible neutron fluence at the payload, the problem of increasing the RE resource or an equivalent decrease in its mass is solved.

 As the calculation showed with respect to a typical nuclear power plant with an electric power of the order of several kV (according to the configuration and relative position of the units, corresponding to the Topaz nuclear power plant (Atomic Energy magazine, vol. 71, 1991, p. 393) for RP with a thickness of about 600 mm, the decrease in its thickness by increasing the straightness of the pipes designed to pass through them through the protection of the reactor control elements, as a result, the reduction of the "lumbar" of ionizing radiation, is about 20 mm, which accordingly reduces the mass of the RE, that is, solves the problem by tion which it is directed claimed invention.

Claims (2)

 1. Radiation protection of a space nuclear power plant, containing a container in the form of a conical shell and bottoms with tubes welded into them, passing through the container, which is filled by casting with lithium hydride, which forms a monolith after solidification, characterized in that each tube is provided with a coaxially located cover inside smaller diameter and flanges, sealing along the end face formed by them an annular cavity into which granular lithium hydride is placed.  2. Radiation protection according to claim 1, characterized in that in the wall of the pipe into which the sheath is placed, an opening is made connecting the cavities of cast lithium hydride and granular.

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