To conduct a nuclear fuel irradiation test, the inside of the nuclear fuel rod must be assembled along with the test fuel, several different parts, and sensors, and then filled with high-pressure and high-purityhelium gas. Therefore, it is necessary to develop helium gas filling techniques that can achieve exact TIG (Tungsten Inert Gas) spot welding at a pin-hole of the nuclear fuel rod to fill helium gas into the nuclear fuel test rod. However, previous apparatuses do not have repeatability for TIG spot welding as they lack an electrode position control jig to exactly fix a TIG electrode in a high-pressure chamber, and they consume a large amount of helium gas. Therefore, a TIG spot welding apparatus was developed to easily and accurately conduct TIG spot welding and significantly reduce the gas consumption. In addition, the optimum welding conditions of this welding apparatus were established through various weld tests.

Fiber laser welding has been developed for precise welding of small and complicate components assembled on the nuclear fuel irradiation test rig. In this research, laser welding characteristics of STS316L, the main material of nuclear fuel test rig, have been studied. Several welding experiments were carried out in lap welding of the tube and the end cap made of STS316L. Process variables such as non-focal length, shield gas, laser frequency and power are optimized and compared with the results of Zircaloy-4.

충남 논산시, 부여군 시설딸기재배지에서 2010년 4∼5월에 40개의 포장의 토양 을 채집하여 식물기생선충을 조사한 결과 뿌리혹선충과 뿌리썩이선충이 우점선충 이었으며 각각 32.5%, 52.5%의 검출율을 보였으며, 평균 밀도는 토양 100g당 뿌 리혹선충은 49마리(J2), 뿌리썩이선충은 328마리였다. 이중 뿌리혹선충과 뿌리썩 이선충이 동시에 감염된 포장은 11개포장으로 27.5%를 보였다. 뿌리혹선충과 뿌 리썩이선충이 동시에 감염된 유기농 딸기 포장의 선충 밀도는 정식시(2009. 9. 7.) 뿌리혹선충과 뿌리썩이선충은 각각 24, 23마리/토양100g에서 5개월후에는 25.8 배(629마리) 24.3배(559마리) 증가하여 피해를 주었다. 두 선충이 감염된 포장의 딸기는 태양열 토양 소독으로 선충을 방제한 포장의 딸기에 비해 지상부 생육과 뿌리의 발달이 저조하였다.