Method for determining real-time thermal power of a nuclear reactor based on number of gamma rays counted

A method comprising

• measuring a number of gamma-ray counts indicative of gamma rays emitted by N16 decay by a gamma-ray detector,
• wherein the gamma-ray detector is positioned at a location that is both:
• outside of a biological shield, and
• inside of an area that includes an exterior section of a primary cooling circuit of a fission nuclear power plant,
• wherein secondary shielding is positioned between the gamma-ray detector and the exterior section,
• wherein the location allows the gamma-ray detector to measure gamma rays originating from the exterior section,
• wherein the location allows for maintenance of the detector during normal operation of the fission nuclear power plant, and
• wherein the number of gamma ray counts is obtained by integrating, by a computing device in real time, the gamma ray spectrum in a predetermined energy range of approximately 6.1 MeV,
• determining, by the computing device in real-time, a thermal power of the fission nuclear power plant based on the number of gamma-ray counts measured by the gamma-ray detector, and
• performing manual maintenance on the gamma-ray detector during normal operation of the fission nuclear power plant, while the gamma-ray detector is at the location.