Nuclear fuel rods and heat pipes in a graphite moderator matrix for a micro-reactor, with the fuel rods having fuel pellets in a BeO sleeve

1 . A nuclear reactor core, comprising:

a plurality of reactor unit cells, wherein at least one of the reactor unit cells comprises:

a graphite moderator matrix;

a plurality of heat pipes positioned in the graphite moderator matrix; and

a plurality of fuel rods positioned in the graphite moderator matrix, wherein at least one fuel rod of the plurality of fuel rods comprises a beryllium-oxide sleeve housing nuclear fuel therein,

wherein the beryllium-oxide sleeve directly surrounds the nuclear fuel.

2 . The nuclear reactor core of claim 1 , wherein a radial gap is defined between the at least one fuel rod and the graphite moderator matrix.

3 . The nuclear reactor core of claim 1 , wherein the beryllium-oxide sleeve comprises a wall thickness in the range of 0.15 cm to 0.4 cm.

4 . A nuclear reactor core, comprising:

a plurality of reactor unit cells comprising a first reactor unit cell and a second reactor unit cell abutting the first reactor unit cell, wherein at least one of the reactor unit cells comprises:

a graphite moderator defining first channels and second channels;

heat pipes positioned in the first channels; and

fuel rods positioned in the second channels, wherein at least one of the fuel rods comprises a beryllium-oxide sleeve housing nuclear fuel therein,

wherein the beryllium-oxide sleeve directly surrounds the nuclear fuel.

5 . The nuclear reactor core of claim 4 , wherein the beryllium-oxide sleeve is to provide protection to the nuclear fuel from migrating metal isotopes from the heat pipes.

6 . The nuclear reactor core of claim 4 , wherein the at least one of the fuel rods further comprises beryllium-oxide pellets positioned in the beryllium-oxide sleeve.

7 . The nuclear reactor core of claim 6 , wherein the at least one of the fuel rods further comprises an end cap coupleable with the beryllium-oxide sleeve, and wherein the beryllium-oxide pellets are positioned between the end cap and the nuclear fuel positioned in the beryllium-oxide sleeve.

8 . The nuclear reactor core of claim 4 , wherein a radial gap is defined between the beryllium-oxide sleeve and the nuclear fuel positioned therein.

9 . The nuclear reactor core of claim 4 , wherein a radial gap is defined between the beryllium-oxide sleeve and the graphite moderator.