In nuclear power plants (NPPs), digital I&C systems are expected to lead to increasing level of safety and improved performance in communication, maintenance, and signal processing. They are expected to be used in all new NPP designs, while existing NPPs are being evaluated for the switch from analog to digital control systems. Switching from analog to digital or working with hybrid systems has posed a bigger challenge than, for example, designing a completely digital control room. The goals of this project are to identify possible faults and to evaluate resiliency of safety-critical digital I&C systems destined for future NPPs . For this purpose, a test bed is being developed which consists of a reactor simulator, a digital controller, and a signal transmitter. A Triple-Modular Redundant (TMR) architecture system is selected as a digital controller for better reliability. A simple real time NPP simulator has been developed in-house in Lab VIEW. A data transmitter and an application program provide the communications between the NPP simulator and the TMR controller. Fault injection techniques are applied to the test bed. The test bed is equipped with a set of specialized fault/error injectors to introduce a range of faults/errors, including both transient and permanent. A fault analyzer is also developed. The paper describes the details of the test bed, the associated fault injection system, and some preliminary results of the fault injection studies for digital I&C of NPPs to assess their reliability, tolerance, and resiliency.