Shutdown justifications

Gruhn, P. and Cheddie, El. 1998, Safety Shutdown Systems Design, Analysis and Justification, ISA. 

Gruhn, P., et al., Safety Shutdown systems Design, Analysis, and Justification, ISA,... 

Gruhn, P., and Cheddie, H., Safety shutdown systems, design, analysis and justification, Instrument Society of America, Research Trirngle Park, NC, 1998. 

For the social criteria, two methods are applied in this study. A more detailed safety-related discussion of the bioethanol process can be found in the open Hterature [45]. In the first method, safety during operation, operability of the plant, safe startup and shutdown, and location-specific demands are selected as four soft indicators for sustainability assessment. The evaluation and justification of each indicator are provided in Table 6.13, where standard definition and scaling system can be found in Othman et al. [1]. In this approach, the process with the higher score is more desirable. Again the dry grind process is found to be superior. 

The Unifonn Listing of C. L, P. and R Reactor Systenu. Acronyms, and Fungtional Classifications (ReC 4 33) provides a current and complete tabulation of system titles, acronyms, and associated fiinctional classifications for principal structures and components. The functional classification NS, CP, PS, or GS) of stiuctures, systems, and components m L and P-Reactors are provided for Cold Shutdown. The report also provides fiinaional descriptions of each sy em during Cold Shutdown and the classification justifications. 

If revised OLCs (e.g., reduced surveillance and maintenance activities) are requested for the extended shutdown, the operating organization needs to justify them. This justification includes the modifications carried out on the reactor systems and equipment. In this case, the SAR is revised and updated. 

In a vessel s operating life, there will be shutdowns and startups. During each of these cycles, the base metal and clad will experience different thermal movements, resulting in shear stresses. These stresses vary as to the relative coefficient of thermal expansion of the two metals. This phenomenon can be analyzed through fatigue analysis, which we will not go into here. The only justification for such an analysis is if many shutdown and startup cycles are expected, resulting in cyclic service. The vast majority of time this phenomenon is not a concern in the operating unit. 

Safety Shutdown Systems Design, Analysis and Justification, ISBN 1-55617-665-1 Paul Gmhn P.E. and Harry CheddieP.E., 1998 ISA, PO Box 12277, Research Triangle Park NC 27709, USA www.isa.org... 

Identified potentials for spurious operations of equipment that could prevent the safe shutdown of the reactors shall be evaluated. On the basis of their significance, the potentials for spurious operation shall be eliminated before restart, or a justification for not eliminating them before restart shall be provided to DOE for review and approval. 

The procedure allows ECS throttling only if certain conditions on process water flow, reactor shutdown time, and leak location isolation are met. In addition, at least one condition on cooling water basin level, ECS flow time, or sump level has to be met to allow ECS throttling. The justification for the most recent throttling limits has been submitted by WSRC and reviewed by the staff. The staff review of this procedure and its technical basis will be documented in Section 11.3 of this SER ("Power Limits"). 

Establish justifications for a sensitive leak detection capability to detect specified small leaks. Demonstrate that this leak detection capability is consistent with technical specifications that specify the operability of leak detection equipment. Conduct appropriate operator training on the leak detection system. Demonstrate that, for detectable leaking cracks, crack growth is slow enough to allow sufHcient time to shutdown the plant. Also show that the through-wall cracks will leak and not plug as a result of impurities or corrosion, or ensure that appropriate margins are used to account for uncertainties. 

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