Gunji Nishio

Pool Fires under Atmosphere and Ventilation in Steady-State Burning (Part II)*

Two pool fire tests for solvent burning were made to obtain the burning rate and the mass loss rate from burning pans under atmosphere and ventilation in a cell. From the data, burning parameters for the Spaldings modified model reported in Part I were determined in steady-state pool burning.

Performance of Containment Sprays for Light Water Reactors and Evaluation of the Heat Transfer

Capacity curves, spray distributions, and droplet size distributions of light water reactor (pressurized water reactor (PWR) and boiling water reactor (BWR)) containment spray nozzles are obtained, and the heat removal effectiveness is evaluated by a computer program CONDENSE. It is revealed by the calculations that spray droplets from a PWR spray nozzle always attain the containment atmosphere temperature and spray droplets from a BWR spray nozzle attain the containment atmosphere temperature above approximately 70/degree/C. 16 refs.

Release of Radioactive Materials in Simulation Tests of a Postulated Solvent Fire in a Nuclear Fuel Reprocessing Plant

This paper reports on small- and large-scale fire tests performed to examine the adequacy of a safety evaluation method for a solvent fire in the extraction process of a nuclear fuel reprocessing plant. The test objectives were to obtain information on the confinement of radioactive materials during a 30% tri-n-butyl phosphate-n-dodecane fire while air ventilation is operating in the cell. The rates of release of cesium, strontium, cerium, ruthenium, and uranium from a burning solvent were determined. The quantities of species released were obtained from the solvent burning rate, smoke generation rate, partition coefficients of species between solvent and water, and coefficients of species entrainment to atmosphere in cell.

Iodine removal tests for BWR containment spray by large scale facility.

Iodine removal tests for a BWR containment spray were carried out with large-scale JAERI Model Containment Test Facility under LOCA simulated conditions. The tests consisted of two groups: “gas-phase based” tests mainly to obtain the initial iodine removal rate by the spray and “liquid-phase based” tests to obtain the iodine partition coefficient at equilibrium state. It was shown that the degree of iodine removal was largely influenced by pH-value of spray water. The results were discussed with calculated results by a code MIRA-PB using a dose reduction factor for the airborne iodine.

Calculation of Iodine Removal by Spray in LWRs Containment Vessels

A computer code MIRA-PB for predicting the iodine removal by containment spray in LOCA was prepared on the basis of MIRA-P/MIRA-B code developed in Battelle Columbus Laboratories. MIRA-PB considers behavior of inorganic iodine, organic iodide, and iodic aerosol and simultaneous removal by natural deposition, liquid-film absorption, spray washout, filtration and leakage to the environment. The iodine removal by the containment spray systems in LOCA of PWR and BWR is calculated with the MIRA-PB.

Fire Behavior and Filter Plugging During a Postulated Solvent Fire in the Extraction Process of a Nuclear Fuel Reprocessing Plant

A solvent fire in the extraction process of a fuel reprocessing plant is postulated. Because of the high concentration of fission products and large amount of nuclear fuel materials in the extraction process, it is necessary to demonstrate that these radioactive materials can be confined by the air ventilation system during a solvent fire. Large-scale tests are performed in a fire/filter facility to evaluate the effectiveness of a ventilation system including high-efficiency particulate air (HEPA) filters to confine radioactive materials. It is demonstrated that the integrity of the filters in the ventilation factor of HEPA filters for smoke particles, which might contain radioactive materials, is sufficiently high during a postulated solvent fire.

Heat Removal Tests for Pressurized Water Reactor Containment Spray by Large-Scale Facility

Heat removal tests for pressurized water reactor (PWR) containment spray were carried out to investigate effectiveness of the depressurization by Japan Atomic Energy Research Institute model containment (7-m diameter, 20 m high, and 708-m/sup 3/ volume) with PWR spray nozzles. The depressurization rate is influenced by the spray heat transfer efficiency and the containment wall surface heat transfer coefficient. The overall spray heat transfer efficiency was investigated with respect to spray flow rate, weight ratio of steam/air, and spray height. The spray droplet heat transfer efficiency was investigated whether the overlapping of spray patterns gives effect or not. The effect was not detectable in the range of large value of steam/air, however, it was better in the range of small value of it. The experimental results were compared with the calculated results by computer code CONTEMPT-LT/022. The overall spray heat transfer efficiency was almost 100% in the containment pressure, ranging from 2.5 to 0.9 kg/cm/sup 2/ X G, so that the code was useful on the prediction of the thermal hydraulic behavior of containment atmosphere in a PWR accident condition.

Evaluation of plutonium oxide aerosol release from an LMFBR in a hypothetical accident

Abstract This work was undertaken to prepare a computer code for the hazard evaluation of plutonium oxide aerosol released to the atmosphere in the event of a hypothetical accident in a 50 MW(th) scale LMFBR. The reactor building structure consists of semi-double containments as follows: the primary containment has a large volume in comparison with the secondary annular containment in which a part is connected to the atmosphere through an emergency filter system. Sodium oxide aerosol containing PuO 2 UO 2 fuel, fission products and structural steel agglomerates quickly by coagulation due to its high concentration. Simultaneously, the aerosol concentration decreases due to settling, plating and thermophoresis. Using the present code, the amount of PuO 2 aerosol leakage to the atmosphere was evaluated.

Development of the face computer code to evaluate the safety of an air ventilation system during a postulated solvent fire in a nuclear fuel reprocessing plant

The FACE computer code was developed to calculate postulated solvent fire behavior in the extraction process of a nuclear fuel reprocessing plant. The FACE code calculates temperature, pressure, an...

Containment Spray Model for Predicting Radioiodine Removal in Light Water Reactors

The computer code COSMO (containment spray model) is prepared to provide information on radioiodine removal by the containment spray of boiling water reactors and pressurized water reactors involving an ice-condenser-type reactor in the event of a loss-of-coolant accident (LOCA). The code considers the removal of inorganic iodine, organic iodide, and particulate iodine in multiple compartments, taking into consideration natural deposition onto the containment wall, spray washout, liquid-film absorption, filtration, and leakage to the environment. The code is also developed by adding many abilities such as the gas convection flow between multicompartment rooms due to fluid disturbance and spray covering onto the inner structures involving the wall in the containment vessels. The calculated results are compared with the iodine removal tests of the Japan Atomic Energy Research Institute model containment, and the iodine removal for light water reactors of 1000 MW(electric) in the postulated LOCA conditions i...