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Advanced Reactor Simulations


ARS Upgrade
Upgrade of the IAEA Advanced Reactor Simulation Software and Training Material.

The International Atomic Energy Agency (IAEA) is assisting developing countries, by the use of reactor simulation, to get experience in the operation of nuclear power plants. The principal objective is to make a "desk top" simulator and a training material available to all Member States, to assist in their comprehension and training programs for nuclear power.

This project will provide insights and understanding of the designs as well as a clear understanding of the operational characteristics of the various reactor types. It requires an emphasis on the basic principles of the operation of each reactor type.

On 8 August, 1996, IAEA retained Dr. Li-Chi Cliff Po of U.S.A. and granted him a Contractual Service Agreement (BC: 100 5050 5410 221 191 A305 D WATER 96CL9125) to prepare the training material for Advanced Reactor Simulation. Dr. Po shall also install the software and carry out the training course in 1997.

Three workshops have been conducted so far: the first from 8 to 13 of November, 1997, in Cairo, Egypt, the second from 16 to 21 of November, 1997, at the IAEA office in Vienna, Austria, and the third from 29 of May to 3 of June, 1998, in Jeddah, Saudi Arabia. Additional workshops have been planned for the latter half of 1998 in Trieste, Italy and Korea. The software package has been distributed to scores of users in 31 countries.

The first part of the Training Package will be the background material. It contains the objectives, scope of simulation, and the principles of operation of each reactor type. It explains the physical principles of a nuclear reactor (power generation and heat removal). Reactivity and the effect of power, temperature, void and control mechanisms (i.e. control rods, soluble boron) on reactivity are to be included.

The second part of the Training Material will be description of the major water-cooled reactor systems: PWR, BWR and PHWR. The principle approach to reactor control using these phenomena for each reactor will be explained. Systems and components designed to address reactor normal and abnormal operation will be described. Sensitivity of the different parameters relevant to the reactor is an important part of this chapter. Consideration of all possible conditions and events will be made systematically regardless of the reactor type. Events that may be important in the case of a BWR should also be discussed for a PWR and shown to be of no importance and vice versa. The objective of this approach is to show the fundamental difference between a BWR and a PWR and the variations in response according to the reactor type.

The third part will be description of the simulated system. The theory and mathematical models of each reactor type will be introduced. The objective is to show to the trainee the general characteristics of a PWR, a BWR or a PHWR, to give him or her a comprehensive understanding of the simulated systems, and to provide instructions for use and exercise of the simulation package. Sample problems will be demonstrated with exercises for diagnosis of unknown events.

Within the Advanced Reactor Simulator, the PWR and BWR modules have been working well, (reflecting the fact the contractor has large contracts with LWR vendors for simulator development). However, a number of required improvements have been identified in the PHWR. These improvements, identified in a review of the code are:

  1. Remodel the reactivity feedback from both the coolant and moderator. By adjusting the positive feedback from coolant void, the kinetics equation will cause a power spike immediately following a major pike break. This positive feedback induced instability during normal operation will be compensated by control system adjustment. A simplified mechanistic model consistent with the CANDU design will be formulated.
  2. On System 2 scram, the strength of the Gadolinium solution will be adjusted so that the power will be less than 15% in 7 seconds after scram initiation.
  3. The Advanced Reactor Simulator training material will be modified to reflect the changes.

If your country is a member state of IAEA and you are interested in IAEA's training program in Advanced Reactor Simulation, please contact your country's representative or the IAEA directly or Mr. Robert Lyon (R.Lyon@iaea.org) of IAEA.


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