Computer Programs

NAME OR DESIGNATION OF PROGRAM, COMPUTER, DESCRIPTION OF PROGRAM OR FUNCTION, METHODS, RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM, TYPICAL RUNNING TIME, RELATED OR AUXILIARY PROGRAMS, STATUS, REFERENCES, HARDWARE REQUIREMENTS, LANGUAGE, SOFTWARE REQUIREMENTS, NAME AND ESTABLISHMENT OF AUTHORS, MATERIAL, CATEGORIES

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Program name | Package id | Status | Status date |
---|---|---|---|

RADTRAD 3.03 | CCC-0800/01 | Arrived | 29-OCT-2012 |

Machines used:

Package ID | Orig. computer | Test computer |
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CCC-0800/01 | PC Windows |

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3. DESCRIPTION OF PROGRAM OR FUNCTION

The potential radiological consequences of nuclear power reactor accidents depend in part upon the amount, form, and species of the radioactive material released during the postulated accident. The RADionuclide Transport, Removal, and Dose (RADTRAD) model estimates doses at offsite locations; for example, the exclusion area boundary (EAB) or the low population zone (LPZ), and in the control room. The code has two optional source terms to describe fission product release from the reactor coolant system: those specified in 'Calculation of Distance Factors for Power and Test Reactor Sites' (TID-14844) along with Regulatory Guides 1.3 and 1.4; and those specified for boiling water reactors (BWRs) and pressurized water reactors (PWRs) in 'Accident Source Terms for Light Water Nuclear power Plants' (NUREG-1465). As radioactive material is transported through the containment, the user can account for sprays and natural deposition that may reduce the quantity of radioactive material. Material can flow between buildings, from buildings to the environment, or into control rooms through high-efficiency particulate air (HEPA) filters, piping, or other connectors. An accounting of the amount of radioactive material retained due to these tortuous pathways is maintained. Decay and in-growth of daughters can be calculated over time as the material is transported. The code contains over 25 model and table options to perform these tasks. It is anticipated that the code will be used to estimate attenuation of source terms as a result of modification for a facility or accident sequence.

The potential radiological consequences of nuclear power reactor accidents depend in part upon the amount, form, and species of the radioactive material released during the postulated accident. The RADionuclide Transport, Removal, and Dose (RADTRAD) model estimates doses at offsite locations; for example, the exclusion area boundary (EAB) or the low population zone (LPZ), and in the control room. The code has two optional source terms to describe fission product release from the reactor coolant system: those specified in 'Calculation of Distance Factors for Power and Test Reactor Sites' (TID-14844) along with Regulatory Guides 1.3 and 1.4; and those specified for boiling water reactors (BWRs) and pressurized water reactors (PWRs) in 'Accident Source Terms for Light Water Nuclear power Plants' (NUREG-1465). As radioactive material is transported through the containment, the user can account for sprays and natural deposition that may reduce the quantity of radioactive material. Material can flow between buildings, from buildings to the environment, or into control rooms through high-efficiency particulate air (HEPA) filters, piping, or other connectors. An accounting of the amount of radioactive material retained due to these tortuous pathways is maintained. Decay and in-growth of daughters can be calculated over time as the material is transported. The code contains over 25 model and table options to perform these tasks. It is anticipated that the code will be used to estimate attenuation of source terms as a result of modification for a facility or accident sequence.

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4. METHODS

It is possible to define a single system of coupled ordinary differential equations (ODEs) that simultaneously represents all of the phenomena considered by the code. However, the size of this equation set, and the computational cost of its numerical integration, would make its implementation impractical on a PC. Significant economies of calculation time and computer memory size in RADTRAD are achieved by dividing the calculations into two parts: (1) transport and (2) radioactive decay.

The fundamental premise behind this approach ensures that during a time step of small enough duration, the interdependence of the two components of the calculations can be neglected. That is, the transport equations defining transfer of material between compartments during a calculation time step can be solved numerically without taking account of the radioactive decay and in-growth occurring over that period. Likewise, the radioactive decay and in-growth equations can be solved during a time step without considering the simultaneous phenomenon of transport between compartments.

The two types of calculations are performed alternately. That is, the code begins its integration over a time step by considering the effect of radioactive decay on the inventory of all compartments. After the consideration of radioactive decay for the time step, the code considers the effect of transport between compartments during that time step. This process of alternating between decay and transport is repeated until the specified end time is reached. During the course of its numerical integration, the code keeps track of the number of atoms of each fission product nuclide in each compartment. Compartments in this sense include not just atmospheric volumes within the plant, but surfaces, pools, and filters as well. By tracking all atoms in this manner, conservation of mass can be verified.

It is possible to define a single system of coupled ordinary differential equations (ODEs) that simultaneously represents all of the phenomena considered by the code. However, the size of this equation set, and the computational cost of its numerical integration, would make its implementation impractical on a PC. Significant economies of calculation time and computer memory size in RADTRAD are achieved by dividing the calculations into two parts: (1) transport and (2) radioactive decay.

The fundamental premise behind this approach ensures that during a time step of small enough duration, the interdependence of the two components of the calculations can be neglected. That is, the transport equations defining transfer of material between compartments during a calculation time step can be solved numerically without taking account of the radioactive decay and in-growth occurring over that period. Likewise, the radioactive decay and in-growth equations can be solved during a time step without considering the simultaneous phenomenon of transport between compartments.

The two types of calculations are performed alternately. That is, the code begins its integration over a time step by considering the effect of radioactive decay on the inventory of all compartments. After the consideration of radioactive decay for the time step, the code considers the effect of transport between compartments during that time step. This process of alternating between decay and transport is repeated until the specified end time is reached. During the course of its numerical integration, the code keeps track of the number of atoms of each fission product nuclide in each compartment. Compartments in this sense include not just atmospheric volumes within the plant, but surfaces, pools, and filters as well. By tracking all atoms in this manner, conservation of mass can be verified.

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CCC-0800/01, included references:

- S. L. Humphreys (SNL), T. J. Heames (ITSC), L. A. Miller (SNL), D. K. Monroe(SNL): RADTRAD: A Simplified Model for RADionuclide Transport and Removal And

Dose Estimation, NUREG/CR-6604 (December 1997).

- N. E. Bixler (SNL), C. M. Erickson (SNL):

RADTRAD: A Simplified Model for RADionuclide Transport and Removal And Dose

Estimation, NUREG/CR-6604 SAND98-0272/1 Supplement 1 (June 1999).

- W.C. Arcieri (ITSC):

RADTRAD: A Simplified Model for RADionuclide Transport and Removal And Dose

Estimation, NUREG/CR-6604 Supplement 2 (October 2002).

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CCC-0800/01

Readme filessource code

pre-compiled Windows executables

test input and output

documentation

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- G. Radiological Safety, Hazard and Accident Analysis
- R. Environmental and Earth Sciences

Keywords: accidental release, dose evaluation, fission products, radioactive release, radionuclide.