The International Atomic Energy Agency’s third standard problem exercise (SPE-3) is simulated with the RELAP5/MOD2 and RELAP5/MOD3 computer codes. The SPE-3 consists of the simulation of the transient resulting from an 11.9% break in the hot collector of the steam generator (primary-secondary leak) of the PMK-NVH test facility. The predicted scenario is compared with the experimental data. Generally, a reasonable agreement between the code predictions and experimental data is obtained. One important calculated parameter that demonstrates deviation from the data is the break mass flow rate. The RELAP5/MOD2 and RELAP5/MOD3 predictions did not display significant differences. This assessment is a part of an international effort for codes/benchmarks.