Calandria nuclear core assembly and method of assembling a nuclear moderator core system

A calandria nuclear core assembly comprising:

• a plurality of neutron moderator elements, each neutron moderator element (NME) having a first end and a second end, each NME defining a through hole extending from the first end to the second end, along an entire length of the NME;
• a plurality of tubes, each tube being located in a respective NME, each tube having a first end portion and a second end portion, the first end portion protruding out of the first end of the respective NME, the second end portion protruding out of the second end of the respective NME;
• a first plate defining a respective plurality of through apertures;
• a second plate defining a respective plurality of through apertures;
• the first end portion of each tube being inserted into a respective through aperture of the first plate;
• the second end portion of each tube being inserted into a respective through aperture of the second plate;
• and
• a peripheral wall surrounding the NMEs and connecting the first plate to the second plate;
• wherein:
• any space between an outside of the first end portion of the tubes and the respective through aperture of the first plate is sealed;
• any space between an outside of the second end portion of the tubes and the respective through aperture of the second plate is sealed;
• the peripheral wall forms a seal with the first plate and with the second plate.

A method of assembling a nuclear moderator core system, the method comprising:

• providing a plurality of neutron moderator elements, each neutron moderator element (NME) defining a through hole, each NME having a first end and a second end, the second end being opposite the first end, each through hole extending between a respective first end and second end;
• installing a plurality of tubes in the plurality of NMEs by having each tube pass through a respective through hole defined by a NME, each tube of the plurality of tubes having a first end and a second end, wherein when the plurality of tubes are installed, each first end of a tube extends out of a respective first end of a respective NME and each second end of the tube extends out of a respective second end of the respective NME;
• inserting the plurality of first ends of tubes into through apertures of a first end plate and securing the plurality of first ends of the tubes to the first end plate;
• inserting the plurality of second ends of tubes into through apertures of a second end plate and securing the plurality of second ends of the tubes to the second end plate;
• connecting the first end plate to the second end plate with a peripheral wall that surrounds the plurality of NMEs, the peripheral wall, the first end plate, the second end plate and the outer surface of the plurality of tubes defining an enclosed space;
• and
• applying a vacuum to the enclosed space to reduce a pressure in the enclosed space, a reduction in pressure to cause the first end plate, the second end plate and the tubes to squeeze against the plurality of NMEs.