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NUREG 0933
Displaying 126 - 150 of 458
DESCRIPTION Consistent with the guidelines of Regulatory Guide 1.7, [1] the prevention of local hydrogen concentrations in excess of 4% by volume after a LOCA requires mixing of the containment atmosphere. Preliminary calculations indicate that lower …
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DESCRIPTION The CONTEMPT computer code is used by the NRC staff to perform independent containment analyses. This NUREG-0471 [1] task involves the maintenance and revision of the CONTEMPT code to accommodate new containment designs or new problem areas as …
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DESCRIPTION Historical Background SRP [1] Section 3.6, issued in 1975, addressed pipe breaks outside containment by combining limited design basis breaks for mechanistic protection with unlimited breaks for non-mechanistic protection. Prior to this, …
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DESCRIPTION Historical Background This NUREG-0471 [1] item involved the development of a time criterion for safety-related operator actions (SROA), including a determination of whether or not automatic actuation was to be required. At the time this issue …
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DESCRIPTION A number of applicants for operating licenses have been performing sump tests to demonstrate ECCS operability during the recirculation phase following a postulated loss-of-coolant accident. These tests have shown that vortex formation is not …
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DESCRIPTION Historical Background The possibility of thermal-hydraulic instability in a BWR had been investigated by GE since the start-up of early BWRs. Analytical methods and codes were formulated on the basis of these early investigations to predict …
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DESCRIPTION Most vendors, in the conduct of internal audits of emergency core cooling performance computer codes, discovered errors in coding and/or logic which had significant effects on the prediction results of approved models. This NUREG-0471 [1] task …
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DESCRIPTION The NRC staff has a variety of ongoing or planned technical activities related to core physics. For the most part, these activities are directed at improving the NRC staff's analytical and computer capabilities for performing independent …
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DESCRIPTION Historical Background Individual reactor fuel rods sometimes fail during normal operations and many fuel rods are expected to fail during severe accidents. To ensure that these fuel failures do not result in unacceptable releases to the …
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DESCRIPTION This NUREG-0471 [1] task covers a spectrum of technical efforts related to the staff review of LMFBR fuel designs. The efforts include: (1) evaluating licensing requirements for the behavior of stainless steel cladding and hexcans in an LMFBR …
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DESCRIPTION The seismic qualification of complex electrical and mechanical components has undergone rapid changes in the past several years. Revisions in industry standards (IEEE 344) have resulted in the need to audit the qualification programs of NSSS …
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DESCRIPTION Applicants are required to provide confirmation of the adequacy of computer programs used in the structural analysis and design of piping systems and components. At the time this issue was identified, this consisted of applicants providing, …
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DESCRIPTION Historical Background As described in NUREG-0471, [1] this issue involves staff evaluations to assess the adequacy of specific containment penetration designs from the point of view of structural integrity, ISI requirements, and new …
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DESCRIPTION Since the adoption by the ASME Code, Section III, of Subsection NF on component supports, technical review has been limited to conformance of the information provided in the application and commitment by the applicants to component support …
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DESCRIPTION As a result of Appendix I and the Liquid Pathway Generic Study, the staff has had to take a more realistic look at the effects of sediment (surface waters) and aquifer materials (groundwater) on radionuclide transport through the hydrosphere. …
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DESCRIPTION This issue was identified in NUREG-0471 [1] and addressed the concerns that the validity of the mathematical models used to predict the performance of dedicated ponds, spray ponds, and cooling towers had not been confirmed, and that better …
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DESCRIPTION This NUREG-0471 [1] task involved the preparation of a paper detailing the bases for design basis flood events utilized by the staff in case reviews, including probable maximum floods, hurricanes, tsunamis, seiches, seismically-induced dam …
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DESCRIPTION Historical Background This issue, as originally stated in 1978, [1] addressed the unavailability (at that time) of a suitable model to predict the erosion rates and, therefore, the flood hydrographs at nuclear power plant sites resulting from …
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DESCRIPTION Historical Background This issue was identified in NUREG-0471 [1] and addressed the concern that additional information was needed on the potential effects of extreme cold weather and ice buildup on the reliability of various plant water …
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DESCRIPTION This NUREG-0471 [1] task involves the maintenance and improvement of calculational capabilities for assessing doses to individuals from radiation and radioactive effluents from normal operation and from radioactive releases from postulated …
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DESCRIPTION Compilation of occupational radiation exposure reports from operating reactors has shown that exposures to station and contractor personnel have generally been increasing over the past 7 years for both PWRs and BWRs. The overriding problem at …
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DESCRIPTION This NUREG-0471 [1] task involves evaluating information from semiannual operating reports, inplant measurements program and topical reports, and revisions to models for calculating releases of radioactive materials in effluents from PWRs and …
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DESCRIPTION This NUREG-0471 [1] item involves developing revisions to current guidance and staff technical positions regarding ESF and normal ventilation system air filtration and adsorption units. This involves developing revisions to Regulatory Guide …
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DESCRIPTION In accordance with licensing responsibilities under the National Environmental Policy Act (NEPA), the NRC is responsible for assessing the impact of licensee's discharges into surface waters. The objective of this assessment is to afford a …
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DESCRIPTION NRC environmental information needs for licensing fall into the categories of: (1) detailed site-specific investigations at a preferred site, and (2) reconnaissance level information to support alternative site assessment and selection, …
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Page Last Reviewed/Updated 3/1/2026
Disclaimer: Some of the formatting in NUREG-0933 may not be correct. We are currently working on fixing the formatting.