Abnormal screened potential of D-D fusion reaction in different host metals, T. Wang, Lanzhou University, School of Nuclear Science,  China − Nuclear reactions occur in planets are mostly under extreme environments.  The reaction cross-section in keV energy region might be significantly affected by surround environment.  For example, the fusion reactions in solar system might be affected by the surround electromagnetic field, temperature and pressure etc. inside the core of sun.  In this work, D-D fusion reaction in Efect. Different screening potentials (Us) have been obtained in targets.  Some Us values are much larger than the electron screening potential.  The enhanced screening effect should be from the host material, but it is difficult to be interpreted by existed theories.  Further experimental and theoretical study should be done in near future.