Experimental Boiling Water Reactor Research Articles

Development of Multi-Functional Telerobotic Systems for Reactor Dismantlement

This report summarizes technological features of advanced telerobotic systems for reactor dismantling application developed at the Japan Atomic Energy Research Institute. Taking into consideration the special environmental conditions in reactor dismantling, major effort was made to develop multifunctional telerobotic system of high reliability which can be used to perform various complex tasks in an unstructured environment and operated in an easy and flexible manner. The system development was carried out through constructing three systems in succession; a light-duty and a heavy-duty system as a prototype system for engineering test in cold environment, and a demonstration system for practical on-site application to dismantling highly radioactive reactor internals of an experimental boiling water reactor JPDR (Japan Power Demonstration Reactor). Each system was equipped with one or two amphibious manipulators which can be operated in either a push-button manual, a bilateral master-slave, a teach-and- playback or a programmed control mode. Different scheme was adopted in each system at designing the manipulator, transporter and man-machine interface so as to compare their advantages and disadvantages. According to the JPDR decommissioning program, the demonstration system was successfully operated to dismantle a portion of the radioactive reactor internals of the JPDR, which used underwater plasma arc cutting method and proved the usefulness of the multi-functional telerobotic system for reducing the occupational hazards and enhancing the work efficiency in the course of dismantling highly radioactive reactor components.

Development of Multi-Functional Telerobotic Systems for Reactor Dismantlement.

This report summarizes technological features of advanced telerobotic systems for reactor dismantling application developed at the Japan Atomic Energy Research Institute. Taking into consideration the special environmental conditions in reactor dismantling, major effort was made to develop multifunctional telerobotic system of high reliability which can be used to perform various complex tasks in an unstructured environment and operated in an easy and flexible manner. The system development was carried out through constructing three systems in succession; a light-duty and a heavy-duty system as a prototype system for engineering test in cold environment, and a demonstration system for practical on-site application to dismantling highly radioactive reactor internals of an experimental boiling water reactor JPDR (Japan Power Demonstration Reactor). Each system was equipped with one or two amphibious manipulators which can be operated in either a push-button manual, a bilateral master-slave, a teach-and- playback or a programmed control mode. Different scheme was adopted in each system at designing the manipulator, transporter and man-machine interface so as to compare their advantages and disadvantages. According to the JPDR decommissioning program, the demonstration system was successfully operated to dismantle a portion of the radioactive reactor internals of the JPDR, which used underwater plasma arc cutting method and proved the usefulness of the multi-functional telerobotic system for reducing the occupational hazards and enhancing the work efficiency in the course of dismantling highly radioactive reactor components.

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Design of Nuclear Reactor Control Systems by the Horowitz Method

In this paper, the Horowitz method is first introduced for the design of nuclear reactor control systems. Then an experimental boiling water reactor (EBWR) is considered. The system can be designed to meet all the specifications, although it has twenty-eight parameters with each of-them having a quite large range of variation. For varifying the design, computer simulations are given.

Minimization of reactor noise through external control

An analytical approach based on the work of Wiener is taken to develop an expression for an optimum linear feedback control system that will minimize the random variations in the flux of a nuclear power reactor. The optimization criterion is the minimization of the mean-square value of these random variations. In determining the optimum control system transfer function, an acceleration constraint is placed on the control-rod drive mechanism. To demonstrate the technique presented, an optimum control system transfer function is derived for the experimental boiling water reactor (EBWR) under specified operating conditions. The changes in the mean-square value of reactor flux caused by varying acceleration constraint level is discussed. Results show that a considerable reduction in the mean-square value of the random flux variations can be obtained through external control.

A multidecade linear reactor simulator

The united States Government exhibit for the 1958 Geneva Conference included a simulation of the main portion of the entire Experimental Boiling Water Reactor (EBWR) plant. The total simulation consisted of two operating panels similar to the EBWR control panels and an animated model of the plant. This discussion is limited to the computer technique utilized to accomplish a linear simulation of the neutron kinetics of the reactor over a full operating range of 8 decades.

Nonlinear Treatment of Large Perturbation in Power Reactor Stability

For large perturbations the usual assuinption in power reactor stability that the flux variations delta n are small in comparison with the steady-state flux level M is not valid. Due to the product term of excess reactivity and neutron flux, harmonics are generated tn the flux. The stability under such conditions can be discussed by extracting the fundamental flux component amd obtaining a quasi frequency response as the ratio of fundamental incremental flux component to excess rcactivity as a function of frequeney and amplitude of perturbation. This approach is applied to two Argonne power reactors, the Experimental Boiling Water Reactor and the Experimental Breeder Reactor, where experimental frequency responses have been obtained and a peak has been observed. It is found that for both reactors the stability decreases as the amplitude of perturbation increases. (auth)

An electronic feedwater control system for the experimental boiling water reactor

The feedwater (FW) system for the Experimental Boiling Water Reactor was designed for utmost flexibility to accommodate many different experiments and procedures scheduled for this facility now in operation at the Argonne National Laboratory. Design criteria called for control of level from either the hotwell or the reactor vessel and ability to switch from simple single-element control (level control adjusting the main FW valve) to 2-element control, using either steam flow (SF) or FWF (FW flow) as the second element, to 3-element control using level, FWF and SF. Further, all of these functions had to be adjustable as to their worth, one to the other, and the final resultant signal to the FW control valve had to be adjustable as to proportional band, reset (integral), and rate action (derivative), to allow 3-function control.

Control Rod Drive Mechanism on the EBWR

The control rod drive mechanlsms installed on the Argonne Experimental Boiling Water Reactor (EBWR) are of an externally operated lead screw and nut type in which the control rod extension shafts are driven through pressure breakdown, collected leakage seals. The mechanisms which are located below the reactor are fabricated from conventional industrial materials, such as carbon steel, brass, cast iron, nylon, etc., and are lubricated with grease. They may be serviced during reactor operation, and are removable from the reactor without the necessity of draining the reactor vessel. This feature has proven to be worthwhile in operation. The mechanism is adaptable to reactors operating at pressures up to 1500 psi and requiring up to a 6-foot control rod stroke. This paper describes the development of the mechanism, the final design and proof- testing program, and some of the particular design difficulties encountered. Some of the other drive types, including electromagnetic jack, hydraulic, and rotary seal rack-and-pinion, considered for EBWR application, are also discussed. (auth)