In order to increase seismic performance of nuclear power plant (NPP) in strong seismic zone, lead-rubber bearing (LRB) can be applied to seismic isolation system of NPP structures. Simple equivalent linear model as structural analysis model of LRB is more widely used in initial design process of LRB than a bilinear model. Seismic responses for seismically isolated NPP containment structures subjected to earthquakes categorized into 5 different soil-site classes are calculated by both of the equivalent linear- and bilinear- LRB models and compared each others. It can be observed that the maximum displacements of LRB and shear forces of containment in the case of the equivalent linear LRB model are larger than those in the case of bilinear LRB model. From the seismic fragility curves of NPP containment structures isolated by LRB, it can be observed that seismic fragility in the case of equivalent linear LRB model are about 5~30 % larger than those in the case of bilinear LRB model.

국내 원자력발전소에서는 사용후핵연료 저장용량의 확대를 위해 사용후핵연료저장조에 조밀저장대를 설치하고 있지만 한 빛원전은 2024년에 포화가 예상된다. 또한 10개의 원자력발전소가 2029년까지 설계수명에 도달하게 된다. 하지만 원전운영 과 해체를 위한 국내 사용후핵연료 관리정책은 아직 결정되지 않은 상황이다. 미국의 경우 원전해체시 사용후핵연료를 중간 저장시설 또는 영구처분장으로 이송하기 전까지 임시적으로 독립된 사용후연료저장조(이하 ‘SFPI’) 방식을 운영하는 사례가 있다. SFPI는 원전해체시 운전정지 후 사용후핵연료를 저장하는데 있어서 방사선 노출 저감, 운영비용 절감, 안전성 보강 등 의 효과를 기대할 수 있다. 따라서 이 논문에서는 미국의 SFPI 운영경험, 시스템, 적용규정 등에 대한 사례연구를 수행하였 다. 결론적으로 SFPI 국내 적용을 위해서는 사용후핵연료저장 계통의 설계변경 범위 및 예상 소요비용 확정, 원전 해체계획 에 설비개선 계획 반영제출, 주기적안전성평가(PSR) 방법 등을 활용한 안전성 평가(운영기간 10 년), 설계변경을 위한 운영 변경허가 신청, 규제기관 심사 및 허가 취득, 설계변경 수행, 규제기관의 확인점검, SFPI 운영을 위한 교육 및 시운전, SFPI 운영 및 정기검사, SFPI 해체 등의 절차가 필요하다.

GRP pipe (Glass-fiber Reinforced Plastic Pipe) lines making use of FRP (Fiber Reinforced Plastic) are generally thinner, lighter, and stronger than the existing concrete or steel pipe lines, and it is excellent in stiffness/strength per unit weight. In this study, we present the result of field test for buried GRP pipes with large diameter(2,400mm). The vertical and horizontal ring deflections are measured for 387 days. The short-term deflection measured by the field test is compared with the result predicted by the Iowa formula. In addition, the long-term ring deflection is predicted by using the procedure suggested in ASTM D 5365(ANNEX) in the range of 40 to 60 years of service life of the pipe based on the experimental results. From the study, it was found that the long-term vertical and horizontal ring deflection up to 60 years is less than the 5% ring deflection limitation.

It is very important to assure the seismic performance of equipment as well as building structures in seismic design of nuclear power plant(NPP). Seismically isolated structures may be reviewed mainly on the horizontal seismic responses. Considering the equipment installed in the NPP, the vertical earthquake responses of the structure also should be reviewed. This study has investigated the vertical seismic demand of seismically isolated structure by lead rubber bearings(LRBs). For the numerical evaluation of seismic demand of the base isolated NPP, the Korean standard nuclear power plant (APR1400) is modeled as 4 different models, which are supported by LRBs to have 4 different horizontal target periods. Two real earthquake records and artificially generated input motions have been used as inputs for earthquake analyses. For the study, the vertical floor response spectra(FRS) were generated at the major points of the structure. As a results, the vertical seismic responses of horizontally isolated structure have largely increased due to flexibility of elastomeric isolator. The vertical stiffness of the bearings are more carefully considered in the seismic design of the base-isolated NPPs which have the various equipment inside.