of Cold Neutron Source of Cold Neutron Source Myong-Seop KIM, - PowerPoint PPT Presentation

2005 TRTR-IGORR Meeting, Gaithersburg Gaithersburg, , September 12-16, 2005 September 12-16, 2005 2005 TRTR-IGORR Meeting, Measurements of Nuclear Heating Rate Measurements of Nuclear Heating Rate and Neutron Flux in HANARO CN Hole and Neutron Flux in HANARO CN Hole for Designing the Moderator Cell for Designing the Moderator Cell of Cold Neutron Source of Cold Neutron Source Myong-Seop KIM, Sung-Yul HWANG, Hoan-Sung JUNG and Kye-Hong LEE Korea Atomic Energy Research Institute KAERI

Introduction-1  Design of cold neutron source facility in HANARO : now in progress.  Heat removal capacity of moderator cell : essential information for source design.  Determination of nuclear heating rate at CN hole of HANARO. Determination of the capacity of refrigerator. 2/11 KAERI

Introduction-2  Nuclear heating : nearly all the energy absorbed in a material placed in the radiation field of a research reactor appears in the form of heat.  Nuclear heating in research reactors : interactions with gamma-rays, fast neutrons and thermal neutrons.  Determination of nuclear heating rate by calorimetric dosimeter (calorimetry) : advantages for high-dose applications.  In this research,  Designing and constructing a calorimeter,  Measuring the nuclear heating rate at CN hole of HANARO with it,  Measuring the thermal neutron flux at CN hole. 3/11 KAERI

Concept of calorimeter operation  In equilibrium condition of steady state, the power integrated over the volume of the sample, = − P hs ( T T ) s e T , s T : sample and container temperatures, e h : heat transfer coefficient, s : sample surface area, 1 / hs : thermal resistance.  If thermal resistance is known, the nuclear heating rate can be obtained by measuring the temperature difference in the steady state. 4/11 KAERI

Experimental setup  Applicable for heating Weight rate measurements in another vertical irradiation holes of HANARO. Sleeve  Components  a calorimeter sensor,  an air containing aluminum sleeve for Sensor fitting the sensor to the CN hole,  aluminum weight,  a lead wire assembly. 5/11 KAERI

Sensor part of calorimeter Al pipe for neutron flux  A cylindrical Al sample. measurement 12 8  Al container.  Al pipe for the neutron flux AlN neutron 80 1.5 11 3 detector for measurement. in-core testing TC1  Two thermocouples. 0.2 mm φ STS wire TC2  Electric heater for a calibration.  Air gap. Heater  Longitudinal center of Al sample Al sample is equal to the center of reactor core.  Calibration : a simulation of the heat transfer of the calorimeter over the temperature range and under the irradiation condition. 6/11 KAERI

Calibration experiments  Installation of facility at CN hole of HANARO (zero reactor power).  Measurements of sample and container temperatures with the electric power supplied to the heater loaded in the sample. ℃  The maximum sample temperature : 385 at 20 W. ℃  The change of container temperature : several .  whole trends of the temperature changes in the calibration experiment.  Temperature change : exponential growth function. 7/11 KAERI

Calibration curve  Relationship between the power supplied to the heater and the temperature difference : not linear.  Convective and radiative heat transfers are increased in high sample temperature range. 8/11 KAERI

Measurements of nuclear heating rate and neutron flux  Measurements of nuclear heating rates at the CN hole at three reactor powers of 1, 4 and 8 MW.  Cobalt wire irradiations at the reactor powers of 1 Detector and 8 MW for the neutron Bias Supply flux measurements.  Measurements of the Analogue Multi- HPGe activities of the withdrawn Preamp Amp Digital Channel Detector Converter Analyzer cobalt samples : HPGe detector system.  The diameter of the cobalt Oscillo- PC scope wire : 0.05 mm (negligible self- shielding effect). 9/11 KAERI

Measured nuclear heating rates-1 Nuclear Reactor Container Sample Temperature Heating rate per heating rate power temperature temperature difference sample unit at sample [ ℃ ] [ ℃ ] [ ℃ ] [MW] mass [W/g] [W] 1.18 31.167 63.284 32.118 0.697 0.018±0.0007 37.051 4.20 122.592 85.540 3.000 0.076±0.0023 8.48 40.158 177.220 137.062 5.618 0.143±0.0041 29.30 19.411 0.494 (30 MW th ) 10/11 KAERI

Measured nuclear heating rates-2 0.16 Heating rate/sample mass [W/g] 0.12 0.08 0.04 Heating rate at 30 MW : 0.494 W/g 0.00 0 2 4 6 8 10 Reactor power [MW] 11/11 KAERI

Measured neutron flux Reactor Co-wire Irradiation Saturated Neutron flux power weight time activity per [n/cm 2 sec] [MW] [mg] [sec] nuclei [Bq] 1.18 0.252 1800 1.224×10 10 3.294 ×10 12 8.48 0.395 600 8.602 ×10 10 2.314 ×10 13 29.30 7.450 ×10 13 (30 MW th ) 12/11 KAERI