This report is the result of a pilot study aiming to survey and give a technical overview of the field of signatures from nuclear weapons. The report gives an overview of both the materials contained within a nuclear explosive device, and the associated radiation processes that occur within the materials. Simulated radiation spectra from a hypothetical nuclear explosive device are presented and are followed by a discussion on measurement conditions for detecting various radiation components. Finally, a compilation of different signatures from various components is presented, followed by a number of suggestions for future research. How individual markers for different materials should be weighted and combined into signatures for a nuclear explosive device is a complex problem, where the sufficient evidence required to conclude that an object constitutes a nuclear weapon, or parts thereof, will be different from case to case. Our wish and hope is that the report will give a fairly comprehensive overview of the problem.