Abstract: In the ICF micro-sphere target filling system, in order to study the recovery of hydrogen isotopes at room temperature by a uranium bed through a small pipe, deuterium pressure (p) in a stainless iron vessel vs time (t) was recorded. The p-t curve was fitted by software Origin, and the fitting curve was discussed. Deuterium gas in a 9×10^-4m³ vessel, flows through 2.3 m stainless iron pipe with inner diameter D＝1-2 mm, and the pressure drops from p₀＝0.6 MPa to zero within 30 s. The gas flow state transits from turbulent flow to laminar flow, according to the calculated average Reynolds number (Re). t＝0-12 s, the relation between p and t satisfies first-order exponential decay curve, i.e., p(t)＝y₀+A₁exp(－t/t₁), in which y₀＝0.05-0.1 MPa, A₁＝0.5-0.6 MPa, t₁＝3.3-3.7 s. y₀ shows the deuterium uptake in the laminar flow state, A₁ refers to initial deuterium pressure p₀. The recovery process can be regarded as a first-order reaction, and the rate-determining step is deuterium diffusion through the gas pipe, reaction constant ＝1/t₁, the half-life of the recovery process in turbulent flow state τ＝t₁ln 2. The reaction constant k rises with reduction of initial deuterium content in U-bed. The condition in the laminar flow state needs further investigation.