[en] The present invention concerns a simulated fuel rod for use in a hot water test for a BWR type reactor. That is, in the simulated fuel rod, insulators are filled in a cladding tube and heat generating materials are buried in the insulation materials. Further, a fine groove is formed on the surface of the cladding tube, and an instrumentation cable is fit in the groove. In the present invention, the gap between the groove and the instrumentation cable is filled with a metal, and the surface of the instrumentation cable is covered with a metal. The surface of the covering metal is made smooth. Usually, upon boiling at the surface of the cladding tube, bubbling starts at a lower surface temperature as the nuclei of the boiling, that is, surface injuries or the like are greater. However, as described above, if the gap between the groove and the instrumentation cable is filled with the metal and the surface of the metal is smooth, since the state of surface is similar to that with no flaws, the surface coarseness is nearly equal with that of an actual fuel rod, and undesirable boiling can be suppressed. As a result, upon hot water test, a boiling state with no difference with the actual fuel rod can be reproduced accurately. (I.S.)