Mechanical analysis of HTR-10 nuclear safety primary pipelines 12 Zhengming Zheng, Wang Minzhi, He Shuyan (Tsinghua University Nuclear Energy Technology Design Institute, Beijing 100084) Abstract: Nuclear safety regulations have detailed provisions for the mechanical analysis of nuclear security primary pipelines, Due to the limitation of calculation methods, the mechanical calculation of nuclear safety first-level pipelines is often very difficult and can not meet the requirements of the analysis method design. This article discusses the use of general finite element software for mechanical analysis of nuclear first-level pipelines. Taking a nuclear safety pipeline system in HTR-10 engineering design as an example, the process of mechanical analysis and mechanical evaluation using MARC general finite element software is introduced, and the focus is on how to meet the mechanical analysis of nuclear 1 pipeline in nuclear safety regulations. Various terms. The method described in this article can be used as nuclear safety! A way of mechanical analysis and mechanical evaluation of high-grade pipelines.
Nuclear-grade pipelines occupy a very important position in nuclear power equipment. The nuclear safety regulations of various countries all stipulate the design, analysis and manufacture of nuclear-grade pipelines. Especially for nuclear safety-grade pipelines, the regulations in the regulations are very detailed. There are many special requirements for calculations. At present, analysis methods are commonly used for design, and mechanical calculations are required to be synchronized with pipeline design. Therefore, mechanical calculations for pipelines are often very urgent.
Table 1 Maximum value of pipeline stress strength Design load / MPa Design load superimposed seismic load / MPa Eye number One time plus two peaks One time plus two peaks 11680159.34159.3427.7024882248.82217. From Table 1, we know the primary stress of 8 pipelines The strength and the strength of the primary and secondary stress are far less than the corresponding stress limit. For the peak stress intensity, it can be evaluated according to two load conditions: under the design load condition, the maximum value of the peak stress intensity is 3, and the alternating stress intensity is â‘´: 4, take the ASME-1 appendix figure- The design fatigue curve of 9.1, corresponding to = 97.03MPa, the number of cycles has tended to infinity, and its cumulative damage coefficient is close to zero.
Under the design load superimposed seismic load condition, the maximum value of the peak stress intensity is 308.22MPa, then the alternating stress intensity is: from the design fatigue curve, it can be checked that it corresponds to Sa = 154.11MPa, and the number of cycles is about 105 times. According to the standard review outline SRP3.7.3, it is generally stipulated that 1 SSE earthquake and 5 OBE earthquakes are assumed within the design life, each earthquake has 10 maximum stress cycles, so that the maximum number of stress cycles generated by the earthquake will not exceed 60 times, the cumulative damage factor is also very small. Therefore, the peak stress intensity can meet the fatigue requirements.
3 Discussion From the perspective of nuclear safety, the primary principle of nuclear engineering mechanics calculation is that it must meet the requirements of nuclear safety regulations. For nuclear safety primary pipelines, the mechanical calculation itself is not difficult. The difficulty lies in how to meet the requirements of nuclear safety regulations. This article is based on the existing calculation methods, trying to perform mechanical analysis and mechanical evaluation of nuclear first-level pipelines in accordance with ASME codes and related regulations as much as possible. The focus of the introduction is also on the satisfaction of the regulations but due to the limitation of calculation conditions, there are the following It is worth discussing: This article does not use professional pipeline calculation software, so some special regulations on pipelines cannot be included, the most important of which is that the correction for the rotation angle is not included when considering the flexibility coefficient (see NB-3686. 2 ) However, due to the small diameter of the pipeline and the large slenderness ratio, it has little effect on the corner correction. Since the pipeline has not been constructed and installed, some parameters such as the radius of the bend and the welding state cannot be finalized, which affects the stress index. After confirming that the pipeline is to be installed, the stress index may change.
When the equivalent static method is used to calculate the element internal force under seismic conditions, the calculation results in the three directions are synthesized by SRSS, which is the regulation of the dynamic analysis method by the regulations, and for the equivalent static method, the regulations do not There is no clear requirement for SRSS synthesis. Although the calculation method described in this article has some imperfections, it can ensure the conservative calculation and also meet the requirements of the nuclear safety regulations. Therefore, it can be used as a primary pipeline for nuclear safety. A convenient engineering practical method for mechanical analysis and mechanical evaluation of B4732-95. An analysis and design standard for steel pressure vessels.
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2 Fund project: National "Eight-six-three" high-tech project (863-514-) 2)
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