Volatilization of B4C control rods in Fukushima Daiichi nuclear reactors during meltdown: B–Li isotopic signatures in cesium-rich microparticles

ABSTRACTIn a future Swedish deep repository for spent nuclear fuel, irradiated control rods from PWR nuclear reactors are planned to be stored together with the spent fuel. The control rod absorber consists of an 80% Ag, 5% Cd, 15% In alloy with a steel cladding. Upon in-reactor irradiation 108Ag is produced by neutron capture. Release of 108Ag has been identified as a potential source term for release of radioactive substances from the deep repository.Under reducing deep repository conditions, the Ag corrosion rate is however expected to be low which would imply that the release rate of 108Ag should be low under these conditions. The aim of this study is to investigate the dissolution of PWR control rod absorber material under conditions relevant to a future deep repository for spent nuclear fuel. The experiments include tests using irradiated control rod absorber material from Ringhals 2, Sweden. Furthermore, un-irradiated control rod absorber alloy has been tested for comparison. The experiments indicate that the release of Ag from the alloy when exposed to water is strongly dependent on the redox conditions. Under aerated conditions Ag is released at a significant rate whereas no release could be measured after 133 days during leaching under H2.

Download Full-text

Verification of the stationary module of the ShIPR software system for modelling experiments of the ASTRA HTGR type critical facility

Kerntechnik ◽

10.1515/kern-2020-850103 ◽

2020 ◽

Vol 85 (1) ◽

pp. 4-8

Author(s):

M. N. Zizin ◽

V. F. Boyarinov ◽

V. A. Nevinitsa ◽

P. A. Fomichenko ◽

Yu. N. Volkov ◽

...

Keyword(s):

Cross Sections ◽

Nuclear Reactors ◽

Reaction Rates ◽

Automatic Generation ◽

Hydraulic Calculation ◽

Monte Carlo Code ◽

Fission Reaction ◽

Development Environment ◽

Transient Conditions ◽

Control Rods

Abstract Coupled neutronic and thermal hydraulic calculation codes are verified for calculating the design of modern and prospective types of nuclear reactors. This verification is done by comparing experimental and calculated results for stationary and transient conditions. This paper presents ShIPR (Shell of Intelligent Package for Reactor) Integrated Development Environment with automatic generation of head programs based on the chain of computational modules. The aim of this study is to find the reason of a discrepancy in the modelling of sub-critical states that was found in previous work. The comparison of ShIPR stationary module with Monte-Carlo code (MCU) and experimental results on ASTRA HTGR critical facility was presented in the paper. To compare the detector readings and MCU calculation with the ShIPR module, the interpolation cross-section procedure was performed. This procedure allows simulating 235U fission reaction rates (detector readings) in the complicate, annular core, using the micro-cross sections prepared by the cell-lattice code. We found that the calculation accuracy of stationary ShIPR module is on an acceptable level but the macro constants for control rods need to be prepared independently, given with surroundings.

Download Full-text

The Properties Research of Hafnium Plate for Control Rod

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.337.494 ◽

2011 ◽

Vol 337 ◽

pp. 494-497

Author(s):

Hong Wen Huang ◽

Xiang Miao Mi ◽

Shan Zhou

Keyword(s):

Mechanical Properties ◽

Corrosion Resistance ◽

Elemental Composition ◽

Nuclear Reactors ◽

Physical Characteristics ◽

Control Rod ◽

Manufacturing Method ◽

Comprehensive Performance ◽

Control Rods

Metallic hafnium has good comprehensive performance that makes it the preferred material for control rods of nuclear reactors. The elemental composition, mechanical properties, the corrosion resistance and the physical characteristics of hafnium plate are researched during the development of control rod for reactors. It proved the manufacturing method of hafnium plate is appropriate, characteristic of materials meet the requirement of a control rod.

Download Full-text

Lifting of evacuation orders and subsequent efforts in Japan

Annals of the ICRP ◽

10.1177/0146645316680577 ◽

2016 ◽

Vol 45 (2_suppl) ◽

pp. 41-47 ◽

Cited By ~ 1

Author(s):

N. Arima

Keyword(s):

Power Plant ◽

Nuclear Power Plant ◽

Nuclear Power ◽

Nuclear Reactors ◽

Japanese Government ◽

Radiological Protection ◽

Individual Dose ◽

Fukushima Daiichi ◽

The Government

With confirmation of the cold shutdown conditions of the nuclear reactors after the accident at Fukushima Daiichi nuclear power plant, the Japanese Government reclassified the areas under evacuation orders as follows: (1) difficult-to-return zones (>50 mSv y−1), (2) restricted residence zones (20–50 mSv y−1), and (3) zones in preparation for lifting of the evacuation order (<20 mSv y−1). The Government continued its initiatives towards reconstruction of Fukushima, and has lifted evacuation orders in Zones 2 and 3. In terms of radiological protection, the Government emphasised its policy of placing importance on individual dose, and promoted the assignment of consultants in each municipality.

Download Full-text