[en] On primary cooling water of TRIGA 2000 reactor monitoring held in 2004, tritium was detected on cooling water at 15 kBq/L and it lead to the atmospheric tritium concentration in reactor hall to be 1.5 Bq/L air. The atmospheric tritium on reactor hall on the form of HTO can be inhaled chronically by radiation worker. The tritium water vapour enter the human body and reach body fluids as target organ, hence the body fluid sample can be used for internal tritium concentration measurement. In this research the urine samples were used. To anticipate the low concentration of tritium in urine samples a sample preparation were applied before measurement using liquid scintillation counter (LSC). Five methods were applied to urine samples by purified the samples to be clear and free from organic matter disturbing the LSC counting. The urin samples obtained from healthy adult were contaminated with tritiated water until the concentration become 0,5 dan 1 Bq/mL. Then the 2 mL of each urine samples were added to the scintillation vial filled with 13 mL of scintillator, and counted using LSC. This is called the direct method. The remained urine samples were prepared. (author)