We used a radiation monitoring and detection system (RMDS) with split-aram technology to measure the radioactivity of soil/waste and a cattle phantom. The system was designed to distinguish between the background and samples contaminated with cesium-137 (137Cs). Before the RMDS trial, the radioactivity levels measured using an NaI (Tl) scintillation counter were 3000 Bq/kg for soil (gross +1.9%, net +5%) and 130,000 Bq/kg for waste (gross +5.7%, net +5.6%). The RMDS provides stable results by performing self-shielding measurements based on passing vehicles after installation. The phantom used for the test was based on a cattle weight of 620 kg. The 137Cs concentration of the phantom assumed a uniform 100 Bq/kg using soil contaminated with 134Cs and 137Cs after the Fukushima Daiichi Nuclear Power Plant accident. Experimental data confirmed the presence of radioactive Cs in the soil. The 620 kg phantom produced measurements of 108.4 + 12.5 Bq/kg (1st run) and 104.9 + 8.0 Bq/kg (2nd run). When a 520 kg phantom was used, the result was 97.4 + 8.7 Bq/kg, and the difference was not significant between the two phantom weights. Should a nuclear disaster recur, the first screening should involve a whole-body counter for livestock, and clean feeding management can reduce the uptake of contaminating radionuclides. Using RMSD measurements of radioactive cesium and a phantom for calibration could contribute to food safety in livestock production.