The new results of experimental studies of fission products release from spent nuclear fuel of the icebreaker “Lenin” reactor dumped in the Kara Sea

Abstract

Abstract. The new technologies were developed for spent nuclear fuel (SNF) condition operative monitoring and search for the lost objects with SNF at the sea bottom using Kr-85. The new paradigm of sea radioecology based on extensive research was proposed. The investigations include a preliminary experimental study of kinetics of fission products (Kr-85 and Cs-137) release from SNF, a subsequent expedition to the Arctic, as well as modeling radionuclides transfer in a near-bottom layer by means of fractal formalism using hydrological data on the expedition area [1,2]. Series of original experimental studies on Kr-85 and Cs-137 release from SNF during corrosion in sea water were conducted in 2002-2010. Time dependence of fission products (FP) release was measured in laboratory under conditions typical of a near-bottom water layer in the Novaya Zemlya Basin. Another important result was received during the expedition to the Arctic in the fall of 2000. The H-3 anomaly was recognized in the surface layer of the Kara Sea in the Novaya Zemlya Basin (228 ± 9.1 TU vs.10-15 TU in the Arctic on average!). This anomaly is located 100 miles south from the dumped reactor of atomic icebreaker "Lenin". So it can be caused by SNF from the reactors of icebreaker "Lenin" or nuclear submarine K-140. EXPERIMENTAL STUDY ON KINETICS OF FISSION PRODUCTS RELEASE IntroductionThe objects with unloaded spent nuclear fuel (SNF) at the sea bottom may cause environmental pollution (for example, in the Arctic) when protective barriers of the SNF assembly are untight. This problem remains the main scientific problem of marine radioecology. At present, methods of episodic radioecological monitoring and numerical simulation cannot give reliable estimates of the radioactive contamination level of the seabed and determine the radiation dose. There is no method available for determination of the beginning of fission products (FP) mass release from SNF to sea water when protective barriers are destroyed. There is the lack of knowledge for time dependence of the processes that influence on SNF safety at the sea bottom is important. The new approach to the problem was developed. It allows to give a conservative estimation of risk of the accident and possible effects on natural and anthropogenic environment in sites of catastrophe and dumping regions of nuclear objects with SNF. Results of the experimental research of FP (Kr-85 and Cs-137) release from the spent oxide nuclear fuel during interaction with sea water are presented. Experimental conditions simulate a zone in dumping regions of nuclear reactors cores. perimental studies on krypton-85 and cesium-137 release from spent nuclear fuelSeries of experimental studies on time dependence of Kr-85 and Cs-137 release from SNF during corrosion in sea water were carried out in NRC "Kurchatov Institute" in 2002.