Nuclear reactor operations

Nuclides formed as a result of nuclear weapons tests, nuclear reactor operations, and other human activities. Important members of this group include 90Sr, 137Cs, 14C, and 3H note that many members of the third group — such as 14C and 3H — are also formed in this fourth fashion (Rose et al. 1990). 

The Sun is a gravitationally confined nuclear reactor operating by thermonuclear fusion. This is the no-nonsense way we view our star today ... 

A lthough the levels of plutonium in environmental waters are generally - low, there is the possibility of plutonium contamination from weapons testing, nuclear reactor operations, laundry and decontamination wastes, fuel reprocessing, and accidental release during transportation. It has been estimated that by 1980 the United States will be producing 15,000-20,000 kg. of plutonium per year (12). Its growing use will increase the probability of environmental contamination. 

All naturally occurring beryllium compounds are. made up of the Be isotope. Artificially produced isotopes occur during some nuclear reactor operations and include 6Be, 7 Be, sBe, and l0Be. 

Proliferation. Nuclear-fuel-cycle operations leave open the possibility of improper access to fissile material through theft or diversion. Proliferation can be addressed through near-term measures designed to improve the proliferation-resistance of current nuclear reactor operations and through long-term research to explore proliferation-resistant designs (PC AST, 1999). 

A typical nuclear industry may consist of mining and milling of uranium ore, thorium extraction, fuel fabrication, nuclear reactor operation, and production and application of radioactive isotopes for various industrial medical and research purposes. Almost, in all these steps, waste is generated that needs proper management. Radioactive wastes differ from other industrial wastes due to its radiation exposure and its radiological toxicity to human beings and their environment. Management of radioactive wastes is an important step in a nuclear industry and the objective is to effectively isolate radionuclides from the... 

Fortunately, for a couple of reasons, the likelihood of a terrorist attack on a nuclear reactor is quite low. Nuclear reactors operate under tight security and incorporate safety systems. In addition, the extensive shielding around reactors would require large amounts of explosives to create a breach. Even if terrorists could transport large amounts of explosives, they would have to breach a security cordon to reach the reactor. Alternatively, they could commandeer a jumbo jet plane to crash into a reactor or a nuclear pond of used cores, but they would have to breach security measures to do so. Computer modeling indicates that the constraction of most reactors would sustain a 300 mph impact from a commercial aircraft, but not aU scientists agree with these findings (1). 

Another case of practical interest in nuclear engineering is the buildup and decay of fission products formed in a nuclear reactor operating at a steady fission rate for a time T and that have been removed from the reactor and aUowed to undergo radioactive decay for an additional time. The schematic diagram for continuous production of the first member of the drain at rate P is... 

Power Production. Steam cycles for generation of electric power use various types of boilers, steam generators, and nuclear reactors operate at subcritical or supercritical pressures and use makeup and often also condensate water purification systems as well as chemical additives for feedwater and boiler-water treatment. These cycles are designed to maximize cycle efficiency and reliability. The fuel distribution of sources installed in the United States from 1990—1995 are as follow coal, 45% combined cycle, 27% miscellaneous, 14% nuclear, 11% solar, oil, and geothermal, 1% each and natural gas, 0.3%. The 1995 summer peak generation in the United States was 620 GW (26). The combined cycle plants are predominantly fired by natural gas. The miscellaneous sources include bagasse, black liquor from paper mills, landfill gas, and refuse (see Fuels frombiomass Fuels fromwaste). 

Nonradioactive cobalt occurs naturally in various minerals, and has been used for thousands of years to impart blue color to ceramic and glass. The radionuclide, cobalt-60, is produced tor commercial use in linear accelerators. It is also produced as a by-product of nuclear reactor operations, when structural materials, such as steel, are exposed to neutron radiation. 

Meshkati has recently studied the concept of a safety culture. Nuclear reactor operators responses to nuclear power plant disturbances is shown in Figure 1 (Meshkati et al. 1994, adapted from Rasmussen 1992). The operators are constantly receiving data from the displays in the control... 

Among the neutron sources related to peaceful uses, the most important are nuclear reactors, which are intended for industrial power production or power supply of special engines from the heat released during a nuclear reaction. Nuclear reactors operate using a controllable neutron chain reaction the system does not reach the explosion state, and, therefore, the neutron flux through the reactor protective shell is relatively weak. 

In the reactor, the process of decay of a heavy nucleus supersaturated with neutrons is initiated by the nuclear-neutron collision because of electrical neutrality even a low-energy neutron can reach the nucleus vicinity, where it can be captured by the short-acting nuclear potential. The result is the creation of a compound nucleus that shortly decays with mission of more neutrons. Nuclear reactors operate by the forced fission of uranium nuclei. There is a number of possible ways in which fission can occur, e.g., decay with the formation of Rb and Cs nuclei and emission of four neutrons instead of a single neutron captured by the U nucleus ... 

The hazard is defined as the nuclear reactor operating at temperatures above the design limits. 

Describe the hazard as a system stale. What other environmental conditions could influence the effect of the hazard occurrence Nuclear reactor operating at temperature above design limits. 

The total number of immediate deaths attributable directly to these incidents over 35 or more years of nuclear reactor operation is less than 35—three at a military prototype reactor in 1981 in the USA and 31 at Chernobyl. However, three subsequent deaths have been reported at Chernobyl (see Appendix 7). Of the fuel meltdown incidents (excluding Chernobyl-4), eight relatively serious incidents have been selected and subjected to some analysis in the following subsection. It is noted that, of these fuel meltdown incidents, only one (Three Mile Island-2) was at an operating, fully developed power plant. All of the other incidents involved research reactors or developmental or prototype plant. Three relatively minor incidents are also reviewed where single channel fuel overheating occurred in graphite-moderated plant. 

T. E.P.Wigner, Nuclear Reactor Operations , Letter to the Editor, Science 205 148 (1979)... 

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). 

Nuclear waste (Section II.A.2) presents even more serious problems than does chemical waste. No method of elimination is possible radioactive material must be sequestered from the environment until it decays, which for some common by-products of nuclear reactor operation will take thousands of years. Continual exposure to radiation promotes deterioration of materials, so nuclear wastes held in aboveground storage or in subsurface tanks must frequently be transferred to new containers. Burial of such wastes has frequently been discussed as a long-term solution to the problem of their disposal, but finding geological formations sufficiently stable and remote from aquifers into which the wastes might migrate has proven to be very difficult. At present, ahention is fo-... 

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