Seung-ok Ko

Measurement of photoneutron spectrum at Pohang Neutron Facility

The Pohang Neutron Facility, an electron linear accelerator (linac) based pulsed neutron facility, was constructed for nuclear data production in Korea. It consists of an electron linac, a water-cooled Ta target with a water moderator, and a time-of-flight path with an 11 m length. The neutron energy spectra are measured for different water levels inside the moderator and compared with calculations by the Monte Carlo N-Particle transport code. The optimum size of the water moderator is determined based on these results.

RaD Status of the 700 MHz, 1MW Klystron for PEFP

KAPRA (Korea Accelerator and Plasma Research Association) are undertaking the first phase R&D for the 1 MW, CW 700 MHz klystron, which is targeting the future stage of the PEFP (Proton Engineering Frontier Project) accelerator at KAERI (Korea Atomic Energy Research Institute). The objectives of the first phase R&D are 1) setting up infra structures/procedures for the design and fabrication, 2) developing a prototype klystron for proofs of principles, and 3) making a performance test of the prototype at a reduced duty. The second phase R&D is supposed to cover full power, CW operation and reliability issues. In this paper, a summary of the R&D status during the first phase for PEFP 1 MW, 700 MHz klystron is reported.

Damage analysis in PFC materials from the D-T nuclear fusion reaction

The interactions of fusion reaction products such as 2.45 MeV and 14.06 MeV neutrons and 3.05 MeV protons with PFC(plasma facing component) are analyzed using Monte Carlo codes. The dpa(displacement per atom) values in the three-layered PFC of graphite, Cu, and SS316L are calculated and the depth profile was analyzed for different-type secondary particles. The PHITS and MCNPX code were used for this study. The products of hydrogen, helium gas were also calculated for analysis of nuclear damage effect. The serious irradiation condition of the ITER parameter, a neutron flux of 3.5×1013 neutrons/cm2·sec, was applied. The dpa values during one year operation were estimated as 0.40-0.75 dpa for graphite, 2.43-4.57 dpa for Cu and 1.78-2.69 dpa for SS316L. The production rate of H, He atom for SS316L is estimated to 316 appm, 42 appm, respectively.

Test of 700MHz, 1MW proto-type klystron for PEFP

High power and RF source of 700 MHz and 1 MW klystron, which has been designed and constructed by the Korean Accelerator and Plasma Research Association, has been tested. To test the primary performance of the klystron, a pulse power supply was used to manipulate a negative high voltage. We are currently reinforcing the protection circuit, and it is going on without much trouble as originally planned. In addition, a baking furnace for the klystron is under fabrication for the ultra high vacuum with better stability. We have constructed various infrastructures such as the baking furnace for the development of the klystron.