가압경수로 고준위페기물 처분용기에 대한 크립해석

Creep Analysis for the Pressurized Water Reactor Spent Nuclear Fuel Disposal Canister

  • 발행 : 2004.12.01

초록

본 논문에서는 깊은 지하 500m에 처분된 가압경수로(PWR) 고준위폐기물 처분용기에 지하수압과 벤토나이트 팽윤압이 가해지는 동안 처분용기에 발생하는 크립변형을 예측하기 위하여 처분용기에 대한 구조해석을 수행하였다. 보통 이러한 크립변형은 처분용기에 추가적인 외력이 작용하지 않더라도 처분용기에 작용하는 압력과 내부의 높은 열에 의하여 발생될 수 있다. 처분용 기내부의 열분포의 복잡성 덴 시간의존성으로 인하여 일단 외부 지하수압 및 팽윤압만 고려하여 크립해석을 수행하였다. 이를 위하여 적당한 크립함수를 사용하였으며, 해석은 1억$(10^8)$초 동안 수행하였다. 해석결과 1억초 동안 발생하는 크립 변형률은 매우 작으며 주희 처분용기의 위아래 덮개에 발생함을 알 수 있었다. 그러나 처분용기의 구조강도에 중요한 내부 주철삽입물에는 훨씬 더 작은 미소한 변형률만 발생하여 처분용기에 발생하는 크립변형은 처분용기의 구조적인 안전성에는 큰 영향을 미치지 않음을 알 수 있었다. 해석 초기에 처분용기 내에 급격히 응력이 증가하여 최고치에 도달한 후 잠깐동안 이 응력 값을 유지하다가 그 이 후에는 급격히 응력 값이 감소하는 응력이완현상을 보이고 있기 때문에 발생 응력 측면에서도 전혀 처분용기의 구조적인 안전성에 문제가 없음이 확인되었다.

In this paper, a structural analysis for the pressurized water reactor(PWR) spent nuclear fuel disposal canister which is deposited under the 500m deep underground is carried out to predict the creep deformation of the canister while the underground water and swelling bentonite pressure are applied on the canister. Usually the creep deformation may be caused due to the Pressure and the high heat applied to the canister even though additional external loads are not applied to the canister. These creep deformations depend on the time. In this paper, oかy the underground water and bentonite swelling Pressure are considered for the creep deformation analysis of the canister, because the heat distribution inside canister due the spent fuel is not simple and depends on time. A proper creep function is adopted for the creep analysis. The creep analysis is carried out during $10^8$ seconds. The creep analysis results show that the creep strains are very small and these strains occur usually in the lid and bottom of the canister not in the cast iron insert. A much smaller strain is found in the cast iron insert. Hence, the creep deformation doesn't affect the structural safety of the canister, and also the creep stress which shows the stress relaxation phenomenon doesn't affect the structural safety of the canister.

키워드

참고문헌

  1. Raiko. H., Salo. J. P., 'Design Report of the Canister for Nuclear Fuel Disposal,' Report POSIVA 96-13, Posiva Oy, Helsinki, ISBN 951-652-012-x, Finland, 1996
  2. Raiko, H., Salo, J.P., 'Design Report of the Disposal Canister for Twelve Fuel Assemblies,' Report Posiva-99-18, Posiva Oy, Helsinki. Finland, 1999
  3. Bond, A. E., Hoch, A. R., Jones, G. D., Tomczyk, A. J., Wiggin, R., M., Worraker, W. J., 'Assessment of A Spent Fuel Disposal Canister', AEA Technology, Harwell, UK. 1997
  4. Mayer, E., 'Spent Fuel Encapsulation Plant, Preliminary Design of Dold-process Plant,' TVO/KPA Turva11isuus Ja Tekniikka, Work Report 89-1, Teollisuuden Voima Oy, Helsinki, 1985
  5. Kwon, Y.J, Kang,S.U., Choi. J.W., Kang,C.H., 'Structural Analysis for the Determination Design Variables of Spent Nuclear Fuel Disposal Canister,'KSME International Journal, Vol.15, No.3, 2001 pp.327-338
  6. Sav$\aa$s, L., 'Canister for Nuclear Waste Disposal. Preliminary Design of the Steel Cylinder,' Arbetsrapport 93-38, VBB Viak AB, Stockholm, Sweden, 1993
  7. O'Neil, W.C., Gregg, D.W., Heckman, J.N., Russel. E.W. Stein, W., 'PreclosureAnalysis of Conceptual Waste Package Design for a Nuclear Waste Repository inTuff.' Lawrence Livermore National Laboratory, 1984
  8. Thunvik, R., Braester, C., 'Heat Propagation from a Radioactive Waste Repository. SKB 91 Reference Canister,' Royal Institute of Technology, Stockholm, Sweden, March, 1991
  9. Renstr$\"o$m, P., 'Heating of Copper/Steel Canisters by Decay Power of Encapsulated Nuclear Waste-Finite Element Analysis,' Arbetsrapport 93-29, VBB Viak AB, Stockholm, Sweden, 1993
  10. 권영주, 하준용, 최종원,'가압경수로 고준위폐기물 처분용기의 열응력 해석,' 한국전산구조공학회 논문집, 제15권 제3호, pp.471-480, 2002
  11. Ahonen, L., 'Chemical Stability of Copper Canisters in Deep Repository,' Report YJ T-94-13, Nuclear Waste Commission of Finnish Power Companies, Helsinki, p.101, 1995
  12. Anttila, M., 'Criticality Safety Calculations for the Nuclear Waste Disposal Canisters,' Report POSIVA-96-11, Posiva Oy, Helsinki, 1996
  13. Anttila, M., 'Criticality Safety Calculations of the Nuclear Waste Disposal Canisters for Twelve Spent Fuel Assemblies', Working Report 99-03. Posiva Oy. Helsinki. 1999, p.20
  14. Auerkari, P., Holmstrom, S., 'Long-term Strength of EB Welds of the Canister forNuclear Fuel Disposal.' Working Report 97-35e, Posiva Oy. Helsinki, p. 21. 1997
  15. Raiko, H., Salo, J. P., 'The Design Analysis of ACP-Canister for Nuclear WasteDisposal,' Report YJT-92-05, Nuclear Waste Commission of Finnish Power Companies, Helsinki, Finland, 1992
  16. Salo, J. P., Raiko, H., 'The Copper/ Steel Canister Design for Nuclear Waste Disposal,' TVO/KPA Turva11isuus Ja Tekniikka, Work Report 90-10, Rev. 1., Teollisuuden Voima Oy, Helsinki. Finland, 1990
  17. Werme, L., 'Design Premises for Canister for Spent Nuclear Fuel,' Technical Report TR-98-08, Swedish Nuclear Fuel and Waste Management Co (SKB), Stockholm, Sweden, ISSN 0284-3757, 1998, p.46
  18. Borgesson, L., 'Interaction between Rock, Bentonite buffer and Canister. FEM Calculations of Some Mechanical Effects on the Canister in Different Disposal Concepts,' Technical report TR 92-20, Swedish Nuclear fuel and Waste Management Co.(SKB), Stockholm. appendixes, ISSN 0284-3757. 1992, p.83
  19. Choi. J.W., Choi, Y.S., Kwon, S.K.. Kuh, J.E., Kang, C.H., 'Technology Assessment of the Repository Alternatives to Establish a Reference HLW Disposal Concept,' Journal of the Korean Nuclear Society, Vol.31. 1999, pp.83-100
  20. Choi. J.W., Ko, W.I., Kang, C.H., 'Reference Spent Fuel and Its Characteriscticsfor a Deep Geological Repository Concept Development,' Journal of the Korean Nuclear Society, Vol.31. No.6, 1999, pp.23-38
  21. Skrzypek, J. J., 'PLASTICITY and CREEPTheory, Examples, and Problems,' CRC Press, 1993
  22. Compiled and Edited by Hagrman. D. L., A. R. Reymann, 'Matro-Version II, a Handbook of Materials Properties for Use in the Analysis of Light Water Reactor Fuel Rod Behavior,' Idaho National Engineering Laboratory, 1979