Moon Saeng Kim

Characteristics of the IR Neutron Beam in Hanaro and the Recent Development for its Use in Dynamic Neutron Radiography

In HANARO, a BNCT facility was built at its IR beam port which can be used for neutron radiography as well. The values of important parameters for neutron radiography such as neutron flux, the L/D ratio and the effective energy of IR beam were obtained. The neutron flux was estimated theoretically by using an MCNP computer code simulation and was also obtained by using gold wire activation method. The L/D ratio was obtained by using the geometrical information for IR beam port as well as by using the Kobayashi’s L/D device. The effective energy was measured by using the Kobayashi’s BQI 1001. These evaluation of beam characteristics shows that the BNCT facility of HANARO is excellent for the dynamic neutron radiography. Introduction The dynamic neutron radiography is a powerful tool for fluid flow visualization as well as the multi-phase flow research[1,2,3]. This technique can be used to investigate the detail behavior of neutron-opaque fluid in metallic enclosure. HANARO is an open pool type research reactor and its design power is 30 MW. It is operated by KAERI(Korea Atomic Energy Research Institute) and a BNCT(Boron Neutron capture Therapy) facility using the IR beam port has been installed. In the development of this facility, it was recognized that this facility could be well suited for dynamic neutron radiography considering its beam characteristics[3]. In this paper, the IR beam characteristics obtained from the code simulations and experiments were given. In addition, the descriptions were made for the recent installation of accessories and a measure to achieve a higher L/D ratio in the BNCT facility. IR Beam Port and BNCT Facility in HANARO HANARO has 7 beam tubes and their arrangement is shown in Fig. 1. The IR beam tube was the only option for the BNCT at HANARO because a BNCT facility was not considered at the design stage of the reactor and any modification of the biological concrete shield was impossible[4]. The details for arrangement of shutter, filter and collimator are in Fig. 2 and the geometric data for the region from the beam nose to an imaging device position are shown in Fig. 3. The beam tube nose made from Zr-4 is located at the position of the peak thermal neutron in D2O reflector region. Considering that Zr-4 is relatively neutron-transparent, the opening edge of beam tube at the reactor vessel boundary is considered as the diaphragm[5]. A long water cylinder plays the role of beam shutter. By hydraulically moving in/out the water in the water cylinder, it plays the role of the beam shutter. A radiation filter for BNCT should remove fast neutrons and gammas but pass more thermal neutrons. A feasibility study on the candidate materials for the filter was performed through computer simulation and the silicon single crystal was chosen for filtering fast neutrons. Its cross section is high for the fast neutron Key Engineering Materials Online: 2004-08-15 ISSN: 1662-9795, Vols. 270-273, pp 1343-1348 doi:10.4028/www.scientific.net/KEM.270-273.1343

Effects of Impact Angle on Cone Crack Formation in Impact-Loaded Soda-Lime Glass

In order to investigate the possibility of punching process of brittle material by ball impact, effects of impact angle on cone crack formation in impact-loaded soda-lime glass were evaluated experimentally. Evaluated were also contact area between specimen and sealing, and the optimal condition for cone crack formation in glass plates by impact with small steel balls. It has been found that lateral and radial cracks gradually developed asymmetrically. However, the perfect cone cracks were found to develop almost symmetrically. As the impact angle increased, the growth rate of cone cracks decreased. Regardless of the impact angle, the PMMA sealing was more effective for perfect cone formation than Aluminum and Polyurethane sealing. Thus, the application for industrial technology for hole (or nozzle) punching process of the brittle materials is expected to be feasible, based upon proper selection of sealing materials.

Impact Fracture Behavior in Alumina Ceramic Plates

In this study, a bar impact test of low velocity was carried out to gain an insight into the damage mechanism and sequence induced in alumina plates during quasi-static impact conditions. An experimental setup which could measure directly the impact force applied to the specimen and supply a compressive pre-stress to the specimen by utilizing an long bar impact was devised. During the bar impact testing, the influence of the pre-stress applied to the specimen along the impact direction on the fracture behavior was investigated. The measured impact force profiles explained well the damage behavior induced in alumina plates. The application of higher pre-stress to the specimen led to less damage due to the suppression of radial cracks which was caused by the increase in the apparent stiffness of the plate. The observed results showed the following sequence in damage development: The development of cone crack at the impact region, the formation of radial cracks from the rear surface of plate depending on the plate thickness, and the occurrence of crushing or fragmentation within the cone envelope.

Frequency Equations for Vibration Analysis of Fuel Rod

In this study, the frequency equations for calculating the natural frequencies of the beams with generally restrained boundary conditions by both translational and rotational springs are derived in matrix form using Fourier sine series. In order to show the validation of the solution, numerical results for two degenerate cases are compared with existing results for natural frequency obtained by the conventional analysis. And as a specific application, the natural frequencies of fuel rod for KSNP (Korean Standard Nuclear Plant) fuel assembly are calculated and compared with the external excitations. As a result, the frequency equation derived by present paper seems to be very useful to evaluate the natural frequencies of the double span beams with various boundary conditions. Especially, when some parametric analyses are needed to modify fuel design, the equation can be applied very easily.Copyright