A 100-Mrad (Si) JFET-Based Sensing and Communications System for Extreme Nuclear Instrumentation Environments

Abstract

Dry cask storage is one of two storage methods approved by the U.S. Nuclear Regulatory Commission for spent fuel after removal from reactor cores. Dry casks consist of a stainless steel canister enclosed in a concrete overpack to contain the hazardous radioactive spent fuel rods and provide radiation shielding. Monitoring spent fuel storage casks is desired to ensure the safe containment of the enclosed spent fuel, but is very difficult due to the related harsh temperature and radiation environment. The sensors and associated electronics to monitor temperature, pressure, and/or radiation need to survive high temperatures and radiation doses for extended time periods. For this reason, there is a severe need for radiation-hardened electrical systems that survive well beyond the existing capabilities of commercially available radiation-rated electronic components, which have primarily been developed for space applications. Junction-gate field-effect transistor (JFET) devices are inherently radiation hardened [exceeding 100 Mrad (Si)]. When JFETs are used as building blocks for sensing and communication electronics (i.e., oscillators, amplifiers, filters, and mixers), inherently radiation-hardened circuits can be achieved. To this end, JFET-based radiation-hardened electronics interfacing with cask-embedded sensors capable of driving modulated sensor signals through a stainless steel barrier were designed and tested at a dose rate of approximately 500 krad/h (Si) to beyond a 200-Mrad (Si) total ionizing dose. After 200 Mrad (Si), the sensor and communication circuit signals were correctly decoded at the receiver despite oscillator drift. The results from this experiment demonstrate the potential for creating more complex radiation-hardened JFET-based electrical systems for nuclear environments.

Keywords:

• Radiation-hardened electronics
• dry cask instrumentation
• through-wall communications
• harsh-environment instrumentation

Acknowledgments

This work was supported by the U.S. Department of Energy (DOE) Nuclear Energy through the Advanced Sensors and Instrumentation (ASI) program under grant DE-NE0008591. In addition, the authors of this paper would like to thank Pattrick Calderoni, Troy Unruh, Dan Sweeney, Mike Heibel, Fred Tompkins, Wayne Johnson, Justine Valka, and Christi Johnson.

This manuscript has been authored by UT-Battelle, LLC under contract DE-AC05-00OR22725 with the DOE. The U.S. government retains and the publisher, by accepting this paper for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this paper, or allow others to do so, for U.S. government purposes. The DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan, http://energy.gov/downloads/doe-public-access-plan.

Disclosure Statement

No potential conflict of interest was reported by the authors.