The boiling flow inside a helical coil steam generator is simulated with the two-fluid model in Nek-2P. Nek-2P is the multiphase branch of the spectral element code Nek5000. Details of the implementation of the two-fluid model and the included closure models are discussed. The presented closure models include interactions for momentum, heat, and mass transfer between phases. The model is fully consistent in the limits of both phasic volume fractions approaching zero and is able to simulate flows of dispersed vapor, continuous liquid, dispersed liquid, continuous vapor or any combination thereof. Results from the simulation of the helical coil indicate strong phasic separation driven by the effects of buoyancy and inertia. Significant differences were observed in the results compared to simulations performed using Star-CCM+, although these differences were somewhat expected.