Transient thermohydraulic characteristics under blowdown conditions simulating a small break LOCA

An experiment simulating a small break LOCA was conducted to get transient thermohydraulic characteristics under blowdown conditions. A uniformly A.C.heated stainless tube (D_i is 11mm, D₀ is 15mm, L is 2000mm) was used in the experiment as the vertical test section, with a solenoid valve simulating a small break at the inlet of the test section. Through the experiment, the relationships that the loop pressure, mass flow rate and wall temperature changed with blowdown time were derived, and the curves reflecting mutual influences between pressure, mass flow rate, initial inlet subcooling and critical time were also obtained. The experimental results presented in this paper have important theoretical and practical significance for study on the transient CHF and critical time to CHF, and, in the meanwhile, they have referential value to operate reactors. The experimental parameter ranges are as follows: p is 0.7-2.2 MPa, △T_sub is 50-120°C; G is 1750-2800Kg/m²·s, q is 0.3-1×10⁶W/m².