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Title: Silver-indium-cadmium control rod behavior and aerosol formation in severe reactor accidents

Abstract

Silver-indium-cadmium (Ag-In-Cd) control rod behavior and aerosol formation in severe reactor accidents are examined in an attempt to improve the methodology used to estimate reactor accident source terms. Control rod behavior in both in-pile and out-of-pile experiments is reviewed. A mechanistic model named VAPOR is developed that calculates the downward relocation and simultaneous vaporization behavior of the Ag-In-Cd alloy expected after control rod failure in a severe reactor accident. VAPOR is used to predict the release of silver, indium, and cadmium vapors expected in the Power Burst Facility (PBF) Severe Fuel Damage (SFD) 1-4 experiment. In addition, a sensitivity study is performed. Although cadmium is found to be the most volatile constituent of the alloy, all of the calculations predict that the rapid relocation of the alloy down to cooler portions of the core results in a small release for all three control rod alloy vapors. Potential aerosol formation mechanisms in a severe reactor accident are reviewed. Specifically, models for homogeneous, ion-induced, and heterogeneous nucleation are investigated. These models are applied to silver, cadmium, and CsI to examine the nucleation behavior of these three potential aerosol sources in a severe reactor accident and to illustrate the competition among these mechanismsmore » for vapor depletion. The results indicate that aerosol formation in a severe reactor accident occurs in three stages. In the first stage, ion-induced nucleation causes aerosol generation. During the second stage, ion-induced and heterogeneous nucleation operates as competing pathways for gas-to-particle conversion until sufficient aerosol surface area is generated. In the third stage, ion-induced nucleation ceases; and heterogeneous nucleation becomes the dominant mechanism of gas-to-particle conversion until equilibrium is reached.« less

Authors:
Publication Date:
Research Org.:
EG and G Idaho, Inc., Idaho Falls (USA); Nuclear Regulatory Commission, Washington, DC (USA). Div. of Accident Evaluation
OSTI Identifier:
6380030
Report Number(s):
NUREG/CR-4876; EGG-2501
ON: TI87010661
DOE Contract Number:  
AC07-76ID01570
Resource Type:
Technical Report
Resource Relation:
Other Information: Includes 2 sheets of 48x reduction microfiche
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; 36 MATERIALS SCIENCE; CADMIUM ALLOYS; CONTROL ELEMENTS; PERFORMANCE; REACTOR SAFETY EXPERIMENTS; INDIUM ALLOYS; RADIOACTIVE AEROSOLS; AEROSOL MONITORING; REACTOR ACCIDENTS; SILVER ALLOYS; ALGORITHMS; EXPERIMENTAL DATA; FLOW MODELS; FORTRAN; MATHEMATICAL MODELS; NUCLEATION; SENSITIVITY ANALYSIS; TEST FACILITIES; TRANSPORT THEORY; V CODES; ACCIDENTS; AEROSOLS; AIR POLLUTION MONITORING; ALLOYS; COLLOIDS; COMPUTER CODES; DATA; DISPERSIONS; INFORMATION; MATHEMATICAL LOGIC; MONITORING; NUMERICAL DATA; PROGRAMMING LANGUAGES; REACTOR COMPONENTS; SOLS; 220900* - Nuclear Reactor Technology- Reactor Safety; 220400 - Nuclear Reactor Technology- Control Systems; 220502 - Nuclear Reactor Technology- Environmental Aspects- Radioactive Effluents; 360104 - Metals & Alloys- Physical Properties

Citation Formats

Petti, D.A. Silver-indium-cadmium control rod behavior and aerosol formation in severe reactor accidents. United States: N. p., 1987. Web.
Petti, D.A. Silver-indium-cadmium control rod behavior and aerosol formation in severe reactor accidents. United States.
Petti, D.A. Wed . "Silver-indium-cadmium control rod behavior and aerosol formation in severe reactor accidents". United States.
@article{osti_6380030,
title = {Silver-indium-cadmium control rod behavior and aerosol formation in severe reactor accidents},
author = {Petti, D.A.},
abstractNote = {Silver-indium-cadmium (Ag-In-Cd) control rod behavior and aerosol formation in severe reactor accidents are examined in an attempt to improve the methodology used to estimate reactor accident source terms. Control rod behavior in both in-pile and out-of-pile experiments is reviewed. A mechanistic model named VAPOR is developed that calculates the downward relocation and simultaneous vaporization behavior of the Ag-In-Cd alloy expected after control rod failure in a severe reactor accident. VAPOR is used to predict the release of silver, indium, and cadmium vapors expected in the Power Burst Facility (PBF) Severe Fuel Damage (SFD) 1-4 experiment. In addition, a sensitivity study is performed. Although cadmium is found to be the most volatile constituent of the alloy, all of the calculations predict that the rapid relocation of the alloy down to cooler portions of the core results in a small release for all three control rod alloy vapors. Potential aerosol formation mechanisms in a severe reactor accident are reviewed. Specifically, models for homogeneous, ion-induced, and heterogeneous nucleation are investigated. These models are applied to silver, cadmium, and CsI to examine the nucleation behavior of these three potential aerosol sources in a severe reactor accident and to illustrate the competition among these mechanisms for vapor depletion. The results indicate that aerosol formation in a severe reactor accident occurs in three stages. In the first stage, ion-induced nucleation causes aerosol generation. During the second stage, ion-induced and heterogeneous nucleation operates as competing pathways for gas-to-particle conversion until sufficient aerosol surface area is generated. In the third stage, ion-induced nucleation ceases; and heterogeneous nucleation becomes the dominant mechanism of gas-to-particle conversion until equilibrium is reached.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1987},
month = {4}
}

Technical Report:
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