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NUREG 0933
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The objective of this task was to improve the reliability and capability of nuclear power plant systems for removing decay heat and achieving safe shutdown conditions following transients and under post-accident conditions. ITEM II.E.3.1: RELIABILITY OF …
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The objective of this task was to improve the reliability and capability of nuclear power plant containment structures to reduce the radiological consequences and risk to the public from design basis events and degraded-core and core-melt accidents. ITEM …
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DESCRIPTION This item was originally identified in NUREG-0371 [1] and was later declared a USI in NUREG-0510. [2] (See Item A-3 for further details.) CONCLUSION This item was RESOLVED and requirements were established. (See Item A-3 for further details.) …
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DESCRIPTION During the conduct of a large scale testing program for an advanced design BWR pressure suppression containment system (MARK III), new suppression pool hydrodynamic loads associated with a postulated LOCA were identified which had not been …
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DESCRIPTION During testing for an advanced BWR containment system design (MARK III), suppression pool hydrodynamic loads were identified which had not been considered in the original design of the MARK I containment system. To address this issue, a MARK I …
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DESCRIPTION As a result of the GE testing program for the MARK III pressure-suppression containment program, new containment loads associated with a postulated LOCA were identified in 1975 which had not been explicitly included in the original design of …
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DESCRIPTION Historical Background Since the issuance of Appendix J to 10 CFR Part 50 in February 1973, certain requirements of the appendix have been found to be conflicting, impractical for implementation, or subject to a variety of interpretations by …
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DESCRIPTION Historical Background The Class 1E power sources provide the electric power for the plant systems that are essential to reactor shutdown, containment isolation, reactor core cooling, containment heat removal or are otherwise essential in …
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DESCRIPTION Historical Background This NUREG-0371 [1] item involves the development of consistent and formalized acceptance criteria regarding the conversion to higher density storage racks (increased storage capacity) in existing spent fuel storage …
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DESCRIPTION Historical Background This issue is documented in NUREG-0371 [1] and addresses the adequacy of safety-related DC power supplies which was questioned by a nuclear consultant in a letter to the ACRS in April 1977 (NUREG-0305, [2] Attachment B). …
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DESCRIPTION This issue was raised in NUREG-0371 [1] following a series of events at operating plants that involved the offsite power systems. These events indicated that the reliability of the preferred source of emergency power might have been less than …
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DESCRIPTION At all nuclear plants, overhead cranes are used to lift heavy objects in the vicinity of spent fuel. If a heavy object such as a spent fuel shipping cask or shielding block were to fall onto spent fuel in the storage pool or reactor core …
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DESCRIPTION The complete loss of AC electrical power to the essential and nonessential switchgear buses in a nuclear power plant is referred to as a "Station Blackout." Because many safety systems required for reactor core decay heat removal are dependent …
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DESCRIPTION The design criteria and methods for the seismic qualification of mechanical and electrical equipment in nuclear power plants underwent significant changes during the course of the licensing of commercial nuclear power plants. Consequently, it …
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DESCRIPTION Following a LOCA in an LWR, combustible gases, principally hydrogen, may accumulate inside the primary reactor containment as a result of: (1) metal-water reaction involving the fuel element cladding; (2) the radiolytic decomposition of the …
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DESCRIPTION Some prototype electrical penetration failures have occurred to date. In addition, failures of low voltage penetration modules have occurred at a licensed facility. It was originally postulated that failures of the low voltage penetration …
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DESCRIPTION Historical Background The description of this item given in NUREG-0471 [1] is as follows: "This is an ACRS generic concern. Evaluation and approval is required of various aspects of the MARK III containment design which differs from the …
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DESCRIPTION The calculations of differential pressure that occur in containment subcompartments from a loss-of-coolant event require a complex fluid dynamic analysis to assure that the subcompartment design pressures are not exceeded. To check the various …
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DESCRIPTION The rationale for normal and postaccident containment cooling will be reviewed to determine the adequacy of the design requirements imposed on the containment ventilation systems. By reviewing typical designs, the staff will develop a basic …
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DESCRIPTION Test data from the Marviken containment tests were obtained for the purpose of validating containment pressure codes used for performing independent calculations related to licensing reviews. The Marviken data are containment pressure …
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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 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 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 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.