Utilization of nuclear energy from various fields of life will produce radioactive waste. Radioactive waste management is carried out according to the type and characteristics of the radioactive waste. Immobilization is an example of a method for managing radioactive waste through compacting or solidifying the waste with a specific matrix to bind and contain the radionuclides. The cementation method is a type of technology for the radioactive waste immobilization method that has been used commercially and proven suitable for use. The main component of cementation is the mortar. This paper aims to determine the effect of fine aggregate (sand) gradation on the compressive strength of the resulting mortar. The research methodology was carried out experimentally. Three types of fine aggregate (sand) are used with IPLN 1, IPLN 2, and IPLN 3 codes. Fine aggregate (sand) has been examined for both silt content (material smaller than 0.075 mm in size), organic content, specific gravity, analysis sand gradation, and fine grain modulus (MHB). From the test results, the fine aggregate (sand) gradations for IPLN 1, IPLN 2, and IPLN 3 are slightly coarse sand, little coarse sand, and fine sand. The fine grain modulus (MHB) of the three types of fine aggregate (sand) are 2.58, 2.46, and 1.8. Only fine aggregate (sand) IPLN 3, whose MHB value is outside the ASTM C33 acceptance criteria, ranges from 2.3 to 3.1. The optimum compressive strength values obtained with three types of fine aggregate (sand) variations, IPLN 1, IPLN 2, and IPLN 3, respectively, were 10.292, 9.411, and 6.026 MPa. Keywords: radioactive waste, cementation, sand, gradation, mortar, compressive strength