John Bernard - Academia.edu (original) (raw)

Papers by John Bernard

AIP Conference Proceedings

AIP Conference Proceedings, 1992

Period-generated control is a method for tracking trajectories that are defined in terms of a dem... more Period-generated control is a method for tracking trajectories that are defined in terms of a demanded rate. It entails computing the control signal needed to achieve a specified trajectory by first using a form of proportional-integral-derivative feedback to generate a demanded inverse period (a velocity) and then substituting that inverse period into a system model. Terms that represent accelerations are included in the model and provide corrective action against deviations from the specified path. A characteristic feature of period-generated control is that rapid adjustments of the control signal are needed whenever a change is made in the demanded trajectory. Advantages to the technique are that it is readily implemented, that it is applicable nonlinear systems, and that the resulting control laws may approach time-optimal behavior for the special case of rate-constrained processes. Period-generated control was developed for the automated operation of nuclear reactors and experiments have been performed to demonstrate its efficacy for that purpose. However, its potential is quite broad and examples are given of its use for the control of non-nuclear systems. In addition, the theory of period-generated control is presented together with an assessment of its major strengths.

Space Station Automation Iv, 1988

Use of the MIT-SNL Period-Generated Minimum Time Control Laws for the automated increase of neutr... more Use of the MIT-SNL Period-Generated Minimum Time Control Laws for the automated increase of neutronic power from subcritical conditions has recently been demonstrated. The use of these laws is advantageous because they provide the speed at which a control device should be withdrawn in order to generate a specific period. Two strategies were investigated. The first was the direct use of the MIT-SNL laws for the entire transient, startup plus operation at power. The second was to add reactivity at a constant rate until criticality was achieved and then to transfer control to the MIT-SNL laws. Each was evaluated by both simulation and actual experiment under conditions of closed-loop digital control on the Annular Core Research Reactor that is operated by the Sandia National Laboratories. Both approaches were shown to be feasible. The former has the advantage that the power profile will be known during the startup. Its drawback is that an excessively high rate of reactivity change may be needed to initiate the transient. The latter requires a lower rate of reactivity change but this rate is still substantial and it must be sustained for a relatively long interval. Material is also presented on the suitability of space-independent kinetics as a reactor model, on the incorporation of source effects in the dynamic period equation, and on aspects of core design that may affect controller performance. The paper concludes with the presentation of a controller structure now being considered for the autonomous control of spacecraft nuclear reactors.

1990 Ieee Nuclear Science Symposium Conference Record, Oct 22, 1990

The Massachusetts Institute of Technology (MIT) Research Reactor (MITR) is owned and operated by ... more The Massachusetts Institute of Technology (MIT) Research Reactor (MITR) is owned and operated by MIT, a nonprofit university. The current reactor, MITR-II, is a 5-MW, light water-cooled and heavy water-moderated reactor that uses materials test reactor-type fuel. Documents supporting application to the U.S. Nuclear Regulatory Commission (NRC) for relicensing of MITR were submitted in July 1999. A power upgrade from 5 to 6 MW was also requested. The relicensed reactor (MITR-III) will be the third reactor operated by MIT. This paper describes MITR-I and MITR-II, and design options considered for MITR-III. Selected problems addressed during the relicensing studies are also described, namely core tank aging evaluation, neutronic analysis, thermal-hydraulic analysis, and step reactivity insertion analysis.

1988 American Control Conference, Jun 15, 1988

A description is given of a model of the Massachusetts Institute of Technology Research Reactor (... more A description is given of a model of the Massachusetts Institute of Technology Research Reactor (MITR) in which both the reactor's neutronic and thermal-hydraulic behaviors are replicated. The purpose of the model is to support control studies and the development of techniques for the automated diagnosis of reactivity transients. In particular, comparison of the model's predictions with actual measurements from the reactor will allow determination of whether the reactor is functioning as expected.

AIP Conference Proceedings, 1992

AIP Conference Proceedings, 1994

AIP Conference Proceedings, 1993

ABSTRACT

1989 American Control Conference, Jun 21, 1989

Journal De Traumatologie Du Sport, Jun 10, 1987

This patent describes an apparatus for closed-loop control of reactor power in a nuclear reactor ... more This patent describes an apparatus for closed-loop control of reactor power in a nuclear reactor in which power level is altered by adjustments in reactivity balance comprising: means for adjusting the reactivity balance; and computing apparatus for computing repeatedly at intervals the two functions (rho(t)-vertical bar rho/sub c/ vertical bar/lambda/sub e/'(t))/vertical bar rho/sub c/ vertical bar and tau(t)ln(P/sub F//P(t); whereby

1990 American Control Conference, May 23, 1990

Advanced nuclear power plants, especially multi-modular designs, will benefit from the implementa... more Advanced nuclear power plants, especially multi-modular designs, will benefit from the implementation of automatic reactor control. A proposed method of non-linear supervisory constraint control is applied to a liquid metal cooled reactor (LMR) module for evaluation. The supervisory element chooses operating set points and ensures that feasibility of control is maintained using a reactivity constraint. A reactor plant model, implemented on a personal computer, is used for controller evaluation. The multi-modular control problem, and proposed supervisory constraint control structure are discussed. Transient simulation results are presented to demonstrate the effectiveness of the proposed controller.

Space Nuclear Power Systems, 1987

The Reactivity Constraint Approach is a method used in automatic reactor control to permit power ... more The Reactivity Constraint Approach is a method used in automatic reactor control to permit power to be raised or lowered in a safe and efficient manner. Following extensive testing, this control methodology was licensed by the U.S. NRC for general use on the 5 MWt MIT Res. Reactor (MITR). The theory underlying the reactivity constraint approach is reviewed with emphasis

AIP Conference Proceedings

AIP Conference Proceedings, 1992

Period-generated control is a method for tracking trajectories that are defined in terms of a dem... more Period-generated control is a method for tracking trajectories that are defined in terms of a demanded rate. It entails computing the control signal needed to achieve a specified trajectory by first using a form of proportional-integral-derivative feedback to generate a demanded inverse period (a velocity) and then substituting that inverse period into a system model. Terms that represent accelerations are included in the model and provide corrective action against deviations from the specified path. A characteristic feature of period-generated control is that rapid adjustments of the control signal are needed whenever a change is made in the demanded trajectory. Advantages to the technique are that it is readily implemented, that it is applicable nonlinear systems, and that the resulting control laws may approach time-optimal behavior for the special case of rate-constrained processes. Period-generated control was developed for the automated operation of nuclear reactors and experiments have been performed to demonstrate its efficacy for that purpose. However, its potential is quite broad and examples are given of its use for the control of non-nuclear systems. In addition, the theory of period-generated control is presented together with an assessment of its major strengths.

Space Station Automation Iv, 1988

Use of the MIT-SNL Period-Generated Minimum Time Control Laws for the automated increase of neutr... more Use of the MIT-SNL Period-Generated Minimum Time Control Laws for the automated increase of neutronic power from subcritical conditions has recently been demonstrated. The use of these laws is advantageous because they provide the speed at which a control device should be withdrawn in order to generate a specific period. Two strategies were investigated. The first was the direct use of the MIT-SNL laws for the entire transient, startup plus operation at power. The second was to add reactivity at a constant rate until criticality was achieved and then to transfer control to the MIT-SNL laws. Each was evaluated by both simulation and actual experiment under conditions of closed-loop digital control on the Annular Core Research Reactor that is operated by the Sandia National Laboratories. Both approaches were shown to be feasible. The former has the advantage that the power profile will be known during the startup. Its drawback is that an excessively high rate of reactivity change may be needed to initiate the transient. The latter requires a lower rate of reactivity change but this rate is still substantial and it must be sustained for a relatively long interval. Material is also presented on the suitability of space-independent kinetics as a reactor model, on the incorporation of source effects in the dynamic period equation, and on aspects of core design that may affect controller performance. The paper concludes with the presentation of a controller structure now being considered for the autonomous control of spacecraft nuclear reactors.

1990 Ieee Nuclear Science Symposium Conference Record, Oct 22, 1990

The Massachusetts Institute of Technology (MIT) Research Reactor (MITR) is owned and operated by ... more The Massachusetts Institute of Technology (MIT) Research Reactor (MITR) is owned and operated by MIT, a nonprofit university. The current reactor, MITR-II, is a 5-MW, light water-cooled and heavy water-moderated reactor that uses materials test reactor-type fuel. Documents supporting application to the U.S. Nuclear Regulatory Commission (NRC) for relicensing of MITR were submitted in July 1999. A power upgrade from 5 to 6 MW was also requested. The relicensed reactor (MITR-III) will be the third reactor operated by MIT. This paper describes MITR-I and MITR-II, and design options considered for MITR-III. Selected problems addressed during the relicensing studies are also described, namely core tank aging evaluation, neutronic analysis, thermal-hydraulic analysis, and step reactivity insertion analysis.

1988 American Control Conference, Jun 15, 1988

A description is given of a model of the Massachusetts Institute of Technology Research Reactor (... more A description is given of a model of the Massachusetts Institute of Technology Research Reactor (MITR) in which both the reactor's neutronic and thermal-hydraulic behaviors are replicated. The purpose of the model is to support control studies and the development of techniques for the automated diagnosis of reactivity transients. In particular, comparison of the model's predictions with actual measurements from the reactor will allow determination of whether the reactor is functioning as expected.

AIP Conference Proceedings, 1992

AIP Conference Proceedings, 1994

AIP Conference Proceedings, 1993

ABSTRACT

1989 American Control Conference, Jun 21, 1989

Journal De Traumatologie Du Sport, Jun 10, 1987

This patent describes an apparatus for closed-loop control of reactor power in a nuclear reactor ... more This patent describes an apparatus for closed-loop control of reactor power in a nuclear reactor in which power level is altered by adjustments in reactivity balance comprising: means for adjusting the reactivity balance; and computing apparatus for computing repeatedly at intervals the two functions (rho(t)-vertical bar rho/sub c/ vertical bar/lambda/sub e/'(t))/vertical bar rho/sub c/ vertical bar and tau(t)ln(P/sub F//P(t); whereby

1990 American Control Conference, May 23, 1990

Advanced nuclear power plants, especially multi-modular designs, will benefit from the implementa... more Advanced nuclear power plants, especially multi-modular designs, will benefit from the implementation of automatic reactor control. A proposed method of non-linear supervisory constraint control is applied to a liquid metal cooled reactor (LMR) module for evaluation. The supervisory element chooses operating set points and ensures that feasibility of control is maintained using a reactivity constraint. A reactor plant model, implemented on a personal computer, is used for controller evaluation. The multi-modular control problem, and proposed supervisory constraint control structure are discussed. Transient simulation results are presented to demonstrate the effectiveness of the proposed controller.

Space Nuclear Power Systems, 1987

The Reactivity Constraint Approach is a method used in automatic reactor control to permit power ... more The Reactivity Constraint Approach is a method used in automatic reactor control to permit power to be raised or lowered in a safe and efficient manner. Following extensive testing, this control methodology was licensed by the U.S. NRC for general use on the 5 MWt MIT Res. Reactor (MITR). The theory underlying the reactivity constraint approach is reviewed with emphasis