When a failure occurs in a nuclear plant, a lack in the response of the controller could lead to serious consequences. The fundamental properties to be ensured by the controller is the plant stability, to be formally proved if possible, and the robustness of the control law, which means fault tolerance and parameter variation tolerance. In this paper, using a mathematical model for the primary circuit of a PWR, accurate enough to catch the nonlinear time-varying, and switching nature of the system, two controllers are designed: an inventory controller for the primary circuit and a pressurizer pressure controller. These controllers do not use direct measurements of the pressurizer pressure or temperature, but use instead pressurizer wall temperature measurements and an observer. Disturbances and parameter variations are compensated by the use of sliding mode estimators, which guarantee robustness to the control scheme. Using an event triggered control control scheme, with varying sampling, the control law has been digitalized for a possible implementation on a digital platform. Copyright © 2015 by JSME.