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in creator/contributor: "Benjamin, A. S."

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Core-Concrete Molten Pool Dynamics and Interfacial Heat Transfer. [Pwr; Bwr]

Theoretical models are derived for the heat transfer from molten oxide pools to an underlying concrete surface and from molten steel pools to a general concrete containment. To accomplish this, two separate effects models are first developed, one emphasizing the vigorous agitation of the molten pool by gases evolving from the concrete and the other considering the insulating effect of a slag layer produced by concrete melting. The resulting algebraic expressions, combined into a general core-co… more

Date: January 1, 1980

Creator: Benjamin, A. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Comparison of Methodologies for Assessing the Risks From Nuclear Weapons and From Nuclear Reactors

There are important differences between the safety principles for nuclear weapons and for nuclear reactors. For example, a principal concern for nuclear weapons is to prevent electrical energy from reaching the nuclear package during accidents produced by crashes, fires, and other hazards, whereas the foremost concern for nuclear reactors is to maintain coolant around the core in the event of certain system failures. Not surprisingly, new methods have had to be developed to assess the risk from… more

Date: August 1, 1996

Creator: Benjamin, A. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Risk Assessment Methodologies for Nuclear Weapons Compared to Risk Assessment Methodologies for Nuclear Reactors

There are major differences between the safety principles for nuclear weapons and for nuclear reactors. For example, a principal concern for nuclear weapons is to prevent electrical energy from reaching the nuclear package during accidents produced by crashes, fires, and other hazards, whereas the foremost concern for nuclear reactors is to maintain coolant around the core in the event of certain system failures. Not surprisingly, new methods have had to be developed to assess the risk from nuc… more

Date: December 31, 1994

Creator: Benjamin, A. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

An Examination of Sandia`S Phenomenological Computer Codes and the Use of Intelligent Searching in Risk Assessments

Because many of the phenomenologically based codes used to support risk assessments require lone execution times, it is important to have a rationally based means for optimizing the choice of parameter values that are input to the code calculations. For this reason, we have developed a method for intelligently searching the space of parameter values to deduce, with as few computations as possible, the values that are most likely to lead to high risk. We have applied the method to a problem invo… more

Date: July 1, 1996

Creator: Benjamin, A. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Development of smart searching algorithms for vulnerability and uncertainty analyses in probabilistic risk assessments

In order to evaluate the risk inherent in a complex system, including a reasonable accounting of the many uncertainties that characterize both the environments to which the system is exposed and the responses of the system to these environments, risk analysts are forced to use statistical approaches. If the system is very well designed for safety, then simple convolution or sampling approaches may have to be augmented by intelligent searching schemes. An excellent example is the prediction of t… more

Date: November 1, 1993

Creator: Benjamin, A. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Modelling of molten fuel/concrete interactions. [PWR; BWR]

A computer program modelling the interaction between molten core materials and structural concrete (CORCON) is being developed to provide quantitative estimates of fuel-melt accident consequences suitable for risk assessment of light water reactors. The principal features of CORCON are reviewed. Models developed for the principal interaction phenomena, inter-component heat transfer, concrete erosion, and melt/gas chemical reactions, are described. Alternative models for the controlling phenomen… more

Date: January 1, 1980

Creator: Muir, J. F. & Benjamin, A. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Development of fast-running thermal and structural response models for probabilistic analysis of complex systems

This paper describes two fast-running physical response algorithms, which were developed for the analysis of nuclear detonation pathways in nuclear weapons systems exposed to fires and crashes but which can be used for other applications such as probabilistic structural analyses of civil systems exposed to dynamic loadings and the dynamic analyses of nuclear reactors exposed to external events. The first is embodied in a computer code called Thermal Evaluation and Matching Program for Risk Appl… more

Date: November 1, 1993

Creator: Benjamin, A. S. & Brown, N. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Spent fuel heatup following loss of water during storage. [PWR; BWR]

An analysis of spent fuel heatup following a hypothetical accident involving drainage of the storage pool is presented. Computations based upon a new computer code called SFUEL have been performed to assess the effect of decay time, fuel element design, storage rack design, packing density, room ventilation, drainage level, and other variables on the heatup characteristics of the spent fuel and to predict the conditions under which clad failure will occur. Possible storage pool design modificat… more

Date: March 1, 1979

Creator: Benjamin, A. S.; McCloskey, D. J.; Powers, D. A. & Dupree, S. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Dynamic modeling of physical phenomena for probabilistic assessment of spent fuel accidents

If there should be an accident involving drainage of all the water from a spent fuel pool, the fuel elements will heat up until the heat produced by radioactive decay is balanced by that removed by natural convection to air, thermal radiation, and other means. If the temperatures become high enough for the cladding or other materials to ignite due to rapid oxidation, then some of the fuel might melt, leading to an undesirable release of radioactive materials. The amount of melting is dependent … more

Date: November 1, 1997

Creator: Benjamin, A. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Design Criteria and Concepts for Vented Containment Systems

Accident sequences from WASH-1400 were selected and analyzed with the MARCH/CORRAL code to provide an envelope of design conditions. The time-dependent pressures and temperatures in containment were calculated as were the concentrations of steam, noncondensible gases, and airborne fission products in the containment atmosphere. The phenomenon found to be most challenging to containment integrity was a pressure spike resulting from rapid steam generation and/or hydrogen burning. The peak pressur… more

Date: January 1, 1980

Creator: Walling, H. C.; Benjamin, A. S. & Cybulskis, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Evaluation of Nonlinear Structural Dynamic Responses Using a Fast-Running Spring-Mass Formulation

In today`s world, accurate finite-element simulations of large nonlinear systems may require meshes composed of hundreds of thousands of degrees of freedom. Even with today`s fast computers and the promise of ever-faster ones in the future, central processing unit (CPU) expenditures for such problems could be measured in days. Many contemporary engineering problems, such as those found in risk assessment, probabilistic structural analysis, and structural design optimization, cannot tolerate the… more

Date: March 1, 1995

Creator: Benjamin, A. S.; Altman, B. S. & Gruda, J. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Dynamic Modeling of Physical Phenomena for Probabilistic Risk Assessments Using Artificial Neural Networks

In most probabilistic risk assessments, there is a subset of accident scenarios that involves physical challenges to the system, such as high heat rates and/or accelerations. The system`s responses to these challenges may be complicated, and their prediction may require the use of long-running computer codes. To deal with the many scenarios demanded by a risk assessment, the authors have been investigating the use of artificial neural networks (ANNs) as a fast-running estimation tool. They have… more

Date: January 1, 1998

Creator: Benjamin, A. S.; Paez, T. L. & Brown, N. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Dynamic modeling of physical phenomena for PRAs using neural networks

In most probabilistic risk assessments, there is a set of accident scenarios that involves the physical responses of a system to environmental challenges. Examples include the effects of earthquakes and fires on the operability of a nuclear reactor safety system, the effects of fires and impacts on the safety integrity of a nuclear weapon, and the effects of human intrusions on the transport of radionuclides from an underground waste facility. The physical responses of the system to these chall… more

Date: April 1, 1998

Creator: Benjamin, A. S.; Brown, N. N. & Paez, T. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Filtered-Vented Containment Systems. [Pwr; Bwr]

The potential benefits of filtered-vented containment systems as a means for mitigating the effects of severe accidents are analyzed. Studies so far have focused upon two operating reactor plants in the United States, a large-containment pressurized water reactor and a Mark I containment boiling water reactor. Design options that could be retrofitted to these plants are described including single-component once-through venting systems, multiple-component systems with vent and recirculation capa… more

Date: January 1, 1980

Creator: Benjamin, A. S.; Walling, H. C.; Cybulskis, P. & DiSalvo, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Evaluation of severe accident risks and the potential for risk reduction: Surry Power Station, Unit 1: Draft report for comment

The Severe Accident Risk Reduction Program (SARRP) has completed a rebaselining of the risks to the public from a particular pressurized water reactor with a subatmospheric containment (Surry, Unit 1). Emphasis was placed on determining the magnitude and character of the uncertainties, rather than focusing on a point estimate. The risk-reduction potential of a set of proposed safety option backfits was also studied, and their costs and benefits were also evaluated. It was found that the risks f… more

Date: February 1, 1987

Creator: Benjamin, A. S.; Boyd, G. J.; Kunsman, D. M.; Murfin, W. B. & Williams, D. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Evaluation of conductive, radiative, chemical, and convective heat transfer in complex systems using a fast-running, implicit, lumped-capacitance formulation

Accurate finite-element simulation of 3-D nonlinear heat transfer in complex systems may require meshes composed of tens of thousands of finite elements and hours of CPU time on today`s fastest computers. To treat applications in which thousands of calculations may be necessary such as for risk assessment or design of high-temperature manufacturing processes, methods are needed which can solve these problems far more efficiently and maintain an acceptably high degree of accuracy. For this purpo… more

Date: May 1, 1995

Creator: Benjamin, A. S.; Beraun, R.; Brown, N. N. & Sherman, M. P.

Item Type: Article

Partner: UNT Libraries Government Documents Department