To access the crucial parameters of a nuclear reactor during station blackout condition, we have proposed a concept of using thermal energy harvester powered sensors and instrumentation with wireless operation. To demonstrate this concept, low power electronics comprising a micro electro mechanical system piezoresistive pressure sensor, amplifier, and wireless transmitter was developed for measurement of pressure in a reactor process. The required electrical power for the sensor and instrumentation was derived from the thermal energy produced by the reactor process itself. A thermoelectric generator was used as an energy harvester for converting the heat energy from the process to electrical energy. A power management circuitry was used for the management of the power which was fed to the sensor and electronics. The complete instrumentation was tested in a test loop to demonstrate the operation of thermal energy harvester powered sensor with wireless operation for static and dynamic pressure measurements. Static pressure, increase or decrease of pressure with time and pressure oscillations were measured in a wireless mode using the developed instrumentation. Differential mode measurements were also carried out. The concept of thermal energy harvester powered sensor and instrumentation presented in this paper would be suitable for wireless sensor network of self-powered/thermal energy harvester powered sensors and for wearable devices by operators. An overview of the design and development of the instrumentation and the results are presented in this paper.