Ju-Chan Lee

Development of Tritium Transport Package for ITER Supply

For tritium supply to the fusion reactor of ITER (The Way to New Energy) [1], tritium need to be transported from tritium production sites, mainly the CANDU type reactor sites to the tritium plant building of ITER. Korea Atomic Energy Research Institute (KAERI) was commissioned the work of developing the transport package for tritium by ITER Organization and the first stage of the development has been just finished. The developed package was designed to carry 70 g of tritium and classified as a type B(U) package, which should comply with the requirements stipulated in IAEA Safety Standard Series [2]. The package is composed of a storage vessel, a containment vessel, an overpack and an aluminum liner which is a unique feature of the package. The aluminum liner between the storage vessel and the containment vessel is for containment control under the repetitive use of the package. The package has enough pressure resistance for 5 year in-site storage and the structural and thermal integrity under the hypothetical accident conditions has been demonstrated through a series of analyses.Copyright

Porous Media Modelling and Verification of Thermal Analysis for Inlet and Outlet Ducts of Spent Fuel Storage Cask

사용후핵연료 저장용기의 공기 흡입구 및 배기구에는 외부환경으로부터 이물질의 유입을 방지하기 위하여 bird screen이 설치되며, bird screen에서는 공기의 유동 저항이 발생하게 된다. 본 연구에서는 Bird screen mesh의 단순화 모델을 이용한 열해석을 수행하기 위하여 다공성매질 해석모델을 개발하였다. CFD 해석을 ...

Safety Evaluation of Radioactive Material Transport Package under Stacking Test Condition

Radioactive waste transport package was developed to transport eight drums of low and intermediate level waste(LILW) in accordance with the IAEA and domestic related regulations. The package is classified with industrial package IP-2. IP-2 package is required to undergo a free drop test and a stacking test. After free drop and stacking tests, it should prevent the loss or dispersal of radioactive contents, and loss of shielding integrity which would result in more than 20 % increase in the radiation level at any external surface of the package. The objective of this study is to establish the safety test method and procedure for stacking test and to prove the structural integrities of the IP-2 package. Stacking test and analysis were performed with a compressive load equal to five times the weight of the package for a period of 24 hours using a full scale model. Strains and displacements were measured at the corner fitting of the package during the stacking test. The measured strains and displacements were compared with the analysis results, and there were good agreements. It is very difficult to measure the deflection at the container base, so the maximum deflection of the container base was calculated by the analysis method. The maximum displacement at the corner fitting and deflection at the container base were less than their allowable values. Dimensions of the test model, thickness of shielding material and bolt torque were measured before and after the stacking test. Throughout the stacking test, it was found that there were no loss or dispersal of radioactive contents and no loss of shielding integrity. Thus, the package was shown to comply with the requirements to maintain structural integrity under the stacking condition.

Evaluation of Cumulative Damage From Drop to Puncture Conditions

During safety assessments of transport packages, cumulative damages are naturally accumulated for assessments performed using physical tests specimens. However, the cumulative damages are not as easily accounted when assessments are by numerical simulations. While analysts are comfortable with simulating packages for single events, it is not yet common practice to incorporate the effect handed over from a former event to the next, in a series of sequential load events. Thus, many numerical simulations in SAR (Safety Analysis Report) represent just a single event in the series of sequential event comprising the required accident condition. These single event numerical simulations are then based on initial conditions different from the analogous physical test specimen, which could contribute to a growing disparity in results between assessments by physically testing compared to numerical simulation. The reason why analyses do not consider the cumulative damage is difficulties in delivering the final result of the previous analysis to the current analysis.The hypothetical accident conditions described in the IAEA regulations include drop, puncture, fire, and water immersion conditions, which should be sequentially simulated. There can be cumulative damage between two accident conditions, such as drop and puncture, puncture and fire, and so forth. In this study, as the first step to consider cumulative damage, an analysis technology to perform a puncture analysis incorporating the final response field from a prior drop analysis is proposed. The necessity and validity of the proposed analysis technology are evaluated by a comparison with the results obtained by performing each analysis independently.Copyright

Design Enhancement of the CANDU Spent Fuel Storage Basket

The necessity of a demonstration test to evaluate the structural integrity of a basket for accident conditions arose during the license approval procedure for the WSPP’s dry storage facility, called MACSTOR/KN-400. A drop test facility for a demonstration was constructed at the KAERI (Korea Atomic Energy Research Institute) site, and demonstration tests for a basket drop were conducted. As the upper welding region of the loaded basket collided with the dropping basket during the drop test, the welding in this region was fractured and a leakage occurred after the drop test. An enhancement of the basket design is needed since the existing basket design was not able to satisfy the performance requirement. The directions for the design modification were determined and six enhanced designs were derived based on these directions. Structural analyses and specimen tests for each enhanced design were conducted. By evaluating the structural analysis and test results, one among six enhanced designs was decided as a final design for revision. The final design was the one that reduced the height of the central post of the basket and decreased the impact velocity with the dropping basket. Test basket models were fabricated in accordance with the final enhanced design. An additional demonstration test was performed for this test model and all the performance requirements were satisfied.Copyright

Evaluation of Structural Integrity for a Dry Storage System With Spacer Disks in a Scale Model Drop Test

A new type of dry storage system has been developed in Korea. The dry storage cask under development consists of a cask body, a canister, and an in-canister structure. The in-canister structure is a complicated structure with many baskets and spacer disks. The spacer disks are originally designed to dissipate the heat from the baskets but they also influence the structural behavior. To evaluate a spacer disks’ influence on the overall structure behavior, especially on the characteristics when it is under a drop test, analyses and tests were conducted. Based on the analysis result, the sensor location and type is determined. Test result is utilized to validate the analysis result. After the drop tests, some strain gauges were detached from the original positions since the relative displacement between a basket and a disk removed the cable from the sensor. Thus, careful attention has to be paid when installing the sensors and cabling inside the in-canister structure. By means of these analyses and tests, the availability of the sensor and cabling arrangement is evaluated and a test procedure is established.Copyright