During the operation of the reactor, a mixture of oxygen, hydrogen, nitrogen, and radioactive gases is produced and stored under pressure in a decay chamber. This review uses numerical simulation methods to study the accumulation and explosion of hydrogen in these mixed gases during storage. The results show that when the initial volume concentration of hydrogen is 0.2%, the maximum volume concentration of hydrogen in the decay box is about 4% after about 1.61 h, the maximum concentration of hydrogen in the decay box is 30% after about 16.79 h, and the concentration is highest at the top of the decay box. As the operating pressure of the decay chamber increases, the maximum explosion pressure of hydrogen gas significantly increases, reaching up to 7.110 MPa.