A nuclear fuel assembly (2) for boiling water reactor comprises a base (4), a head (6), a bundle of fuel rods (8) extending longitudinally between the base (4) and the head (6), a tubular fuel channel (14) encasing the bundle of fuel rods (8), and at least one fuel channel spacer (22) for transversely spacing the fuel assembly (2) from an adjacent element. According to one aspect of the invention, the or each fuel channel spacer (22) comprises a support (34) having at least one plate (38) and at least one corresponding leaf spring (36) supported by the corresponding plate (38), the or each plate (38) being fixed to a corresponding sidewall (26) of the fuel channel (14).