Margin between safety and disaster concerned with nuclear power generation entities
The concern for nuclear power safety was initiated by the International Atomic Energy Agency (IAEA) about 12 years after World War II. Within the commercial arena alone, the safety issues connected with nuclear power generation of electricity are already enormous. They can involve the interactive changes of the combined effects of technical, ecological, economical, social, and political. The heart of the nuclear power plant is the nuclear reactor that can be PWR, BWR, GMR (RBMK) and MSR. Safety operational regulations are presently concerned mostly with the PWR and BWR to which the US NRC coordinates with 14 other countries. As commendable as the tasks performed by the Nuclear Regulatory Commission (NRC) for the past 30 years and more, Codes & Standards (C&S) do age and amendments are necessary. This is especially true for those that require the support of hard core science and advanced technology. Advanced physical laws and computational schemes can enhance the C&S. The revision, validation, and revalidation of the NRC-ASME &Ⅲ/Ⅺ codes, about 10 years ago under the VOCALIST program, however, have not lived up to their intention. The Elastic-Plastic Fracture Mechanics (EPFM) code as part of PVC (Pressure Vessel Code) lost credibility as the elastoplasticity-based J-Integral had no connection with the dislocation theories that were assumed to provide the theoretical mechanics foundation for elastoplasiticy. This hope vanished after the NRC C&S codes were prematurely installed. The possible uses of multiple scaling were by passed, since the 1990s. Certainly, nuclear power safety will not wait for NRC to recognize Multiscale Fracture Mechanics (MFM). Particularly vulnerable are the use of commercial black box programs based on mono-scale parameters such as theJ-, C- and C*-Integral for characterizing inherently dual- or multiscale-damage processes that are referred to as Elastic & Plastic (E&P), Creep & Fatigue (C&F), and Stress Corrosion Cracking (SCC). Future code development connected with the Liquid Salt Very High Temperature Reactor (LS-VHTR) cannot afford to disregard the life expectancy of the critical components for each scale range from nano to macro. The J- and C*-Integral are mono-scale by definition. Their replacement by the Generalized Crack Extension Energy (GCEE) G can be accomplished simply by altering the specimen thickness, and loading rate for a given material using Multiscale Fracture Mechanics (MFM). The suggested approach is heuristic since adjustments are needed to remove the ambiguities in applying the J- and C*-Integral. The global (load) energy transferred to the crack tip had to be measured correctly. This required a knowledge that the singularity point (absorbing-dissipating energy in tandem) can be assumed to characterize the phantom crack tip as inhaling and exhaling in breathing at the different spatial-temporal scales. Keep in mind that not all of the input energy is absorbed. Some can be dissipated. This mass pulsation behavior is described in the theory of Crack Tip Mechanics (CTM). The pulsation energy model was necessary for determination of the multiscale crack tip location. A consistent interpretation of the fracture mechanics test data was thus made possible. The mission of NRC envisioned by the Energy Reorganization Act (ERA) of 1974 was to oversee reactor safety and security, reactor licensing and renewal. While the choice of nuclear power plant (NNP) type is influenced by democracy, technocracy, and sciocracy, the rules governing nuclear safety, however, should follow hard core science and not decided by the expediency of the establishment. The Fukushima disaster has indeed pointed out the need to delineate these differences and to scrutinize the present system of administering and defining nuclear safety. Predicting the unpredictable stood out as a key issue. The need for a research operational group is apparent. It can be dubbed as Think Tank for Nuclear Power Safety (TTNPS) with the mission to translate theoretical concepts from formal economics and hard science into seemingly unquantifiable predictions. It is not unthinkable that the unexpectable can be converted to the expectable. Careful thought should be given to placing safety before cost or reducing cost at the expense of safety.
Think tank Structural integrity Nuclear Safety Disaster Beyond design Climate change Risk Cost
G C. Sih
International Center for Sustainability, Accountability and Eco-Affordability of the Large and Small (ICSAELS) Lehigh University,Bethlehem PA 18015, USA Key Laboratory of Pressure Systems and Safety, Ministry of Education, School of Mechanical Engineering and Power Engineering, East China University of Science and Technology, Shanghai 200237, China
国际会议
2011 International Symposium on Structural Integrity 2011国际结构完整性学术研讨会--核工程结构完整性技术 ISSI 2011
合肥
英文
1-16
2011-10-27（万方平台首次上网日期，不代表论文的发表时间）