A new kind of optical dosimetry such as the in-core power monitoring and gamma ray thermometer using radio luminescence and thermal radiation due to gamma ray in optical fibers was demonstrated. During heavy irradiation in the core region of JMTR fission reactor, optical fiber kept good transmission characteristics and radio luminescence and thermal radiation appeared in the infrared region. Intensities of radio luminescence and thermal radiation were found to be directly proportional to the reactor power. Also, temperatures could be estimated by thermal radiation of Planck's law. The optical measuring method using optical fiber could be used to compose simple and convenient monitoring system of power and temperature as a reactor dosimetry.

Comprising the proceedings of the Tenth International Symposium on Reactor Dosimetry held in Osaka, Japan in September 1999, this volume contains some 100 papers, plus three keynote speeches, arranged in seven sections that cover the technical scope of the symposium. The first two sections consist o

Lifetime extensions of nuclear fission reactors in the UK are required to satisfy growing demands for electrical power. Many of these reactors are nearing the end of their original design life, so the continued structural integrity, particularly of the reactors' prestressed concrete pressure vessels and containments is of prime concern. Currently, a lift-off inspection of a 1 % random sample of prestressing tendons is performed at 18 month to 5 year intervals to ensure adequate prestress is present in these structures, but the extended life times are making higher resolution, more frequent and in-depth monitoring techniques more desirable. In this thesis, a method of instrumenting prestressing strands with optical fibre Bragg grating strain sensors is outlined. An all-metal encapsulation and bonding technique is developed to ensure sensor reliability under the radioactive and high-stress environments of fission reactors. This 'smart strand' is complemented by a specially developed interrogation scheme capable of continuously and automatically monitoring static and dynamic nanoscale changes in Bragg grating strain. High-resolution interrogation was achieved by extending an interferrometric demodulation technique into the static measurement regime. By modulating the strain sensitivity using a fast optical switch, strain signals could be recovered independently of noise sources using various signal processing algorithms. The application of this technology could augment the continued monitoring of concrete vessel integrity, reducing both the risks and costs associated with performing lift-off measurements in the current and next generation of nuclear reactors.

"In this dissertation, the effects of radiation (gamma, neutron or mixed gamma and neutron) on optical fiber sensors are studied and new techniques for real-time measurement of radiation-induced macroscopic changes in optical fibers are presented. It is crucial among the research and development efforts in the nuclear energy field to conduct experiments in Advanced Test Reactor (ATR) to support lifetime extension, novel fuels and materials development, better fuel management, and enhanced safety of existing as well as future nuclear power plants (NPP). Due to their unparalleled and unique advantages over traditional sensors, optical fiber sensors are deemed potential candidates for their use in nuclear environments. However, optical fibers are susceptible to high levels of ionizing radiation emitted by fission reactors which are characterized by the highest levels of gamma dose, high flux of neutrons and potentially high temperatures depending on location in a reactor core. It is essential to accurately determine the information related to physical parameters such as temperature, pressure, and strain in nuclear environments for the safety of the existing and future NPPs."--Boise State University ScholarWorks.

Optical Fiber Sensor Technology, Advanced Applications - Bragg Gratings and Distributed Sensors, builds upon the foundations of the subject in the preceding four volumes of this series, concentrating as they do upon both applications and the technology of advanced optical fiber sensors. Previous volumes have covered the fundamentals of the field, devices and systems and chemical and environmental monitoring. This volume deals with a range of highly topical sensor devices and commercial systems, with considerable emphasis upon one of the most important areas, Bragg gratings in fibers, their fabrication and applications in advanced sensor systems and the principles and use of distributed fiber optic sensors. The volume is well illustrated and referenced, pointing to hundreds of key publications accessible in the open literature. It draws upon a group of authors with an international reputation for their work in the area, carefully edited into a coherent and logical text by the editors, based on their considerable experience in the field. This book series will provide an invaluable source for researchers, engineers and advanced students in the field of optical fibers, optoelectronics and measurement and sensing.