A unit cell configured to remove heat generated by a nuclear reactor, the unit cell comprising: a core block material; and a plurality of devices disposed throughout the core block material, wherein at least one device of the plurality of devices comprises a heat pipe (100; 200; 401; 501) comprising: a length; an inner housing comprising an outer surface, wherein the inner housing defines an inner volume configured to accommodate a heat source (102; 202); an outer housing comprising an inner surface, wherein the outer housing is configured about the inner housing and the heat source (102, 202); a wick (112; 212) positioned between the inner housing and the outer housing and extending along at least a portion of the length of the heat pipe (100; 200; 401; 501), wherein the wick (112; 212) comprises a capillary material, wherein the wick (112; 212) is configured to contact at least a portion of the outer surface of the inner housing, wherein the wick (112; 212) is configured to contact at least a portion of the inner surface of the outer housing, and wherein the wick (112; 212) defines an intermediate volume between the inner housing and the outer housing; and a working fluid within the intermediate volume, wherein the working fluid is configured to evaporate at a first end of the heat pipe (100; 200; 401; 501), wherein the working fluid is further configured to condense at a second end of the heat pipe (100; 200; 401; 501), wherein the wick (112; 212) is configured to return working fluid that has condensed at the second end of the heat pipe (100; 200; 401; 501) to the first end of the heat pipe (100; 200; 401; 501), and wherein the evaporation and condensation of the working fluid is configured to transfer heat from the first end of the heat pipe (100; 200; 401; 501) to the second end of the heat pipe (100; 200; 401; 501) for dissipation via a heat exchanger. a core block material; and a plurality of devices disposed throughout the core block material, wherein at least one device of the plurality of devices comprises a heat pipe (100; 200; 401; 501) comprising: a length; an inner housing comprising an outer surface, wherein the inner housing defines an inner volume configured to accommodate a heat source (102; 202); an outer housing comprising an inner surface, wherein the outer housing is configured about the inner housing and the heat source (102, 202); a wick (112; 212) positioned between the inner housing and the outer housing and extending along at least a portion of the length of the heat pipe (100; 200; 401; 501), wherein the wick (112; 212) comprises a capillary material, wherein the wick (112; 212) is configured to contact at least a portion of the outer surface of the inner housing, wherein the wick (112; 212) is configured to contact at least a portion of the inner surface of the outer housing, and wherein the wick (112; 212) defines an intermediate volume between the inner housing and the outer housing; and a working fluid within the intermediate volume, wherein the working fluid is configured to evaporate at a first end of the heat pipe (100; 200; 401; 501), wherein the working fluid is further configured to condense at a second end of the heat pipe (100; 200; 401; 501), wherein the wick (112; 212) is configured to return working fluid that has condensed at the second end of the heat pipe (100; 200; 401; 501) to the first end of the heat pipe (100; 200; 401; 501), and wherein the evaporation and condensation of the working fluid is configured to transfer heat from the first end of the heat pipe (100; 200; 401; 501) to the second end of the heat pipe (100; 200; 401; 501) for dissipation via a heat exchanger. a length; an inner housing comprising an outer surface, wherein the inner housing defines an inner volume configured to accommodate a heat source (102; 202); an outer housing comprising an inner surface, wherein the outer housing is configured about the inner housing and the heat source (102, 202); a wick (112; 212) positioned between the inner housing and the outer housing and extending along at least a portion of the length of the heat pipe (100; 200; 401; 501), wherein the wick (112; 212) comprises a capillary material, wherein the wick (112; 212) is configured to contact at least a portion of the outer surface of the inner housing, wherein the wick (112; 212) is configured to contact at least a portion of the inner surface of the outer housing, and wherein the wick (112; 212) defines an intermediate volume between the inner housing and the outer housing; and a working fluid within the intermediate volume, wherein the working fluid is configured to evaporate at a first end of the heat pipe (100; 200; 401; 501), wherein the working fluid is further configured to condense at a second end of the heat pipe (100; 200; 401; 501), wherein the wick (112; 212) is configured to return working fluid that has condensed at the second end of the heat pipe (100; 200; 401; 501) to the first end of the heat pipe (100; 200; 401; 501), and wherein the evaporation and condensation of the working fluid is configured to transfer heat from the first end of the heat pipe (100; 200; 401; 501) to the second end of the heat pipe (100; 200; 401; 501) for dissipation via a heat exchanger.