NUREG 0933
Displaying 176 - 200 of 458
DESCRIPTION Decommissioning is defined as the orderly retirement of a nuclear facility from service and the safe disposition of the remaining radioactivity. 10 CFR 50.82 provides the regulations that govern the termination of licenses. The NRC may require …
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DESCRIPTION Historical Background This NUREG-0471 [1] task is to develop and confirm a model for the iodine spiking phenomenon, in which the iodine concentration in the reactor coolant rises to many times its equilibrium concentration level (peak …
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DESCRIPTION The control room area ventilation systems and control building layout and structures are reviewed to assure that plant operators are adequately protected against the effects of accidental releases of toxic and radioactive gases and to assure …
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DESCRIPTION According to NUREG-0471, [1] the nature of this problem is described as follows: "Monitoring of radioactivity in gaseous and liquid effluent streams from nuclear power plants is required for several purposes: (a) assessment of the adequacy of …
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DESCRIPTION Historical Background This NUREG-0471 [1] item, as presently formulated, involves the conduct of analytical and experimental work to determine whether or not destructive overspeeds could be attained and to determine if corrective actions are …
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DESCRIPTION Following a plant transient or accident, provisions are required for long-term decay heat removal. Redundancy of components is required as necessary to assure that a failure in the RHR system will not impair the ability to maintain the plant …
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DESCRIPTION Offsite power system frequency decay, depending on the rate of decay, could provide an electrical brake on the reactor coolant pump motors that could slow the pumps faster than the assumed flywheel coastdown flow rates normally used in …
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DESCRIPTION Present NRC actions taken in response to a serious incident are directed from an Incident Response Center (IRC). To implement an adequate response, it is necessary that the IRC be equipped with appropriate communications services, information …
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DESCRIPTION Practice in health impact assessments at the time of identification of this issue was to convert radiation exposure estimates into estimates of health effects, such as cancer deaths, illness, and life shortening. However, the models that were …
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DESCRIPTION Historical Background The ACRS raised a concern that there is a need to develop criteria for vibration monitoring systems which could provide early warning of excessive vibration inside the reactor vessel. This item is documented in …
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DESCRIPTION Historical Background This NUREG-0471 [1] item was developed because of concerns regarding the long-term capability of hermetically- sealed instruments and equipment which must function in postaccident environments. Certain classes of …
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DESCRIPTION Inadvertent operation of containment sprays can result in a rapid depressurization of the containment building. Where containment external design pressure may be exceeded, many plants have been provided with vacuum breakers or control system …
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DESCRIPTION Various kinds of insulation are used on piping and components inside the containment of a nuclear power plant. The concern of this NUREG-0471 [1] item was the behavior of insulation under pipe break accident conditions where the potential …
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DESCRIPTION Historical Background As identified in NUREG-0471, [1] Appendix K of 10 CFR 50 specifies the requirements for LWR ECCS analysis. These requirements call for specific conservatisms to be applied to certain models and correlations used in the …
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DESCRIPTION Historical Background As identified in NUREG-0471, [1] this issue involved following the work of research groups in determining best estimate decay heat data and associated uncertainties for use in LOCA calculations. Safety Significance No …
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DESCRIPTION Historical Background As identified in NUREG-0471, [1] this issue involved staff evaluations of vendors' data and approaches for determining LOCA heat sources and developing staff positions as needed. The contributors to LOCA heat sources, …
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DESCRIPTION Combinations of fabrication, stress, and environmental conditions have resulted in isolated instances of stress corrosion cracking of low pressure Schedule 10 Type 304 stainless steel piping systems. Although these systems are not part of a …
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DESCRIPTION Historical Background Dose calculations by AAB/NRR in 1975 indicated that operation of the main steam isolation valve leakage control system (MSIVLCS) required for some BWRs could result in higher offsite accident doses than if the system were …
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DESCRIPTION Historical Background A BWR RHR system is designed for: (1) containment spray/suppression pool cooling, (2) fuel pool cooling augmentation, (3) low pressure coolant injection, and (4) bringing the reactor down to a cold shutdown condition. …
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DESCRIPTION This NUREG-0471 [1] task will respond to a concern of the ACRS about the effectiveness of various containment sprays to remove airborne radioactive materials which could be present within the containment following a LOCA. This concern has been …
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DESCRIPTION Historical Background The operating experience of nuclear power plants indicates that a number of valves, valve operators, and pumps fail to operate as specified in the technical specifications either under testing conditions or when they are …
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DESCRIPTION Historical Background Structural damage to the primary system, including the reactor pressure vessel and internals, associated piping and steam generator tubing in PWRs, can be caused by vibrations of sufficient magnitude. These vibrations can …
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DESCRIPTION This NUREG-0471 [1] item was an ACRS generic concern that initially addressed the common mode failure of identical components exposed to identical or nearly-identical conditions or environments. This concern was later expanded to include other …
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DESCRIPTION Licensees are required to estimate the design-basis flood levels for each nuclear power plant site consistent with the requirements in General Design Criterion 2, "Design Bases for Protection against Natural Phenomena," of Appendix A, "General …
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DESCRIPTION SRP [1] Section 15.7.3 requires an analysis of the consequences of failure of tanks containing radioactive liquids outside containment. This NUREG-0471 [2] task involves the development of a NUREG report that will describe a consistent and …
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Page Last Reviewed/Updated 3/1/2026
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