Nuclear Reactor Accident Analysis

In 1967, E R. Farmer of the United Kingdom proposed that the probabilities as well as consequences of potential accidents need to be estimated to assess the associated risk. Farmer used 1-131 as a surrogate for consequences. By plotting the probability and consequence of each postulated accident, one could distinguish those with high risk from those with low risk. He proposed a boundary line as a criterion for acceptable risk. Farmer s work was a conceptual breakthrough in nuclear reactor safety analysis. Farmer takes full credit as the originator and pioneer of PRA. 

K. K. Murata et al., User s Manual for CONTAIN 1.1 A Computer Code for Severe Nuclear Reactor Accident Containment Analysis , NUREG/CR-5026, SAND87-2309, Sandia National Laboratories, November 1989. 

Accident Analysis During Melt-Down of a Nuclear Reactor 395... 

Accident analysis during melt-down of a nuclear reactor. The problem to be considered here is the erosion of concrete by liquid material during a melt-... 

Systems analysis was also an integral part of the U.S. nuclear navy. The stringent standards imposed by Admiral Rickover to do with both nuclear safety and personnel selection have been a critical factor in the navy s continuing record of zero reactor accidents. 

ABSTRACT The analysis of events during the accident at Three Mile Island concluded that the accident was due to confused control room operators with inadequate instrumentation and inaccurate procedures. Therefore, the United States Nuclear Regulatory Commission (USNRC) called for improved nuclear reactor operator training and Emergency Operating Procedures (EOPs). 

As a result of the analysis of events during the accident at the Three Mile Island nuclear plant (TMI, March 1979), the importance of human error in nuclear plants was better understood. The accident resulted from the confusion of the control room operators with inadequate instrumentation and inaccurate procedures. The most important factor was that they had to act in spite of the weaknesses in the training to respond to unexpected events. Therefore, the United States Nuclear Regulatory Commission (USNRC) called for the improvement of Emergency Operating Procedures (EOPs) and in nuclear reactor operator training. The philosophy of incident response implemented in the improved procedures was to take a symptom-based approach (operators foUow a series of yes - no questions to ensure that the reactor core remains covered and only then determine what was the cause of the problem) (USNRC, 2009). 

Accident Analysis for Nuclear Power Plants with Graphite Moderated Boiiing Water RBMK Reactors... 

ACCIDENT ANALYSIS FOR NUCLEAR POWER PLANTS WITH GRAPHITE MODERATED BOILING WATER RBMK REACTORS... 

Accident analysis for nuclear power plants with graphite moderated boiling water RBMK reactors. — Vienna International Atomic Energy Agency, 2005. 

Consistent with these publications, the IAEA in 2002 issued a detailed report on Accident Analysis for Nuclear Power Plants (Safety Reports Series No. 23) that provides practical guidance for performing accident analysis. That report covers the steps required for accident analyses, i.e. selection of initiating events and acceptance criteria, selection of computer codes and modelling assumptions, preparation of input data and presentation of the calculation results. It also discusses aspects that need to be considered to ensure that the final accident analysis is of acceptable quality. Separate IAEA Safety Reports deal with specific features of individual reactor types, such as pressurized water reactors, boiling water reactors, pressurized heavy water reactors and RBMKs. 

There is an enormous number of radioanalytical procedures based on solvent extraction and here it is only possible to give a few examples. The examples chosen have been taken from the analysis of samples from the European PHEBUS project performed at the Nuclear Chemistry, Chalmers University of Technology. Very briefly, the Phebus reactor was used to study the products formed in severe reactor accidents. The released gases and aerosols were collected in filters and in water at different positions in the experimental setup. 

In this process, each commercial nuclear power plant application must undergo a safety review (SR), an environmental review, and antitrust review by the NRC staff. The applicant must submit a safety analysis report (SAR) that contains the plant design information and criteria for the proposed nuclear reactor as well as comprehensive data on the proposed site. Also, this document should discuss various postulated accident scenarios and the plant-specific safety features that are designed to prevent accidents or mitigate their consequences should they occur. Furthermore, the application must contain a comprehensive assessment of the environmental impact of the proposed plant. Finally, the applicant must submit information for antitrust reviews of the proposed plant. 

This section discusses the laws that have defined the processes for developing the hazard and accident analysis and the controls necessary to ensure the safe operation of government-owned contractor-operated nuclear reactors and nuclear facilities. 

The deterministic approach to the design of nuclear reactors was rapidly supplemented by the development of probabilistic studies, referred to as PSAs and also as PRA. The first study of this kind carried out in the United States was published in 1975 (Rasmussen report—USNRC 1975) and provided the first assessment of the potential risk of core damage for two power reactors. The accident in 1979 at the Three Mile Island plant generated renewed interest in this type of study. One of the recommendations made after the accident was that probabilistic analysis techniques should be used to supplement conventional safety assessment procedures for NPPs, and that probabilistic objectives should be developed in order to facilitate the determination of acceptable safety levels for nuclear facilities. 

XXV-7] ZAKI, S., SEKIMOTO, H., Accident Analysis of lead or lead-bismuth cooled small safe long-life fast reactor using metallic and nitride fuel. Nuclear Engineering and Design, 162, pp. 205-222 (1996). 

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