Engine Shutdown System

Most engines are operated in an unattended manner. Shutdown safety devices must be provided to prevent engine damage in case of a malfunction. Some of the more common engine shutdowns are  

Low lube oil flow—lube oil to the stroke power cylinder 

This is not to be taken as a complete shutdown list. Installation and operating requirements may dictate other safety precautions. This list does not include any safety devices that would be associated with the driven equipment. 

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The HWR has an inherent prompt shutdown mechanism (besides the engineered shutdown systems [SDSs] and the control system) for beyond-design-basis severe core damage accidents. If steam is introduced into the moderator as a result of, for example, multiple... 

These problems ean result in sudden loss of power beeause a fault is sensed by the engine eontrol system and the engine is shutdown. 

Active—Using controls, safety interlocks, and emergency shutdown systems to detect and correct process deviations e.g., a pump that is shut off by a high level switch in the downstream tank when the tank is 90% full. These systems are commonly referred to as engineering controls. 

Green, D. L., and A. M. Dowell (1996). Cookbook Safety Shutdown System Design. i996 Process Plant Safety Symposium, Volume 1, April 1-2,1996, Houston, TX, ed. H. Cullingford, 552-565. Houston, TX South Texas Section of the American Institute of Chemical Engineers. 

Active controls use engineering controls, safety interlocks and emergency shutdown systems to detect process deviations and take appropriate corrective or remedial action. Their effectiveness depends on proper selection, installation, testing, and maintenance. 

Instrument engineers provided a high tube-wall-temperature shutdown system to protect the heater. The initial design and prevailing practices allowed the shutdown temperature setpoint to be adjusted by the operator without any formal approval or authorization system. Perhaps the rather primitive (by todays standards) safety instrumented system had given troubles, been a nuisance, and become a victim of a one-minute modification. 

The term engineered safety covers the provision in the design of control systems, alarms, trips, pressure-relief devices, automatic shutdown systems, duplication of key equipment services and firefighting equipment, sprinkler systems, and blast walls, to contain any fire or explosion. 

KALIMER has enhanced safety features with the use of metallic fuel, Self-Actuated Shutdown System (SASS), Gas Expansion Module (GEM) in the core, and Passive Safety Decay Heat Removal System (PSDRS). Utilization of these enhanced safety features eliminates the need for diverse and redundant engineered safety systems and KALIMER accommodates unprotected anticipated transients without scram (ATWS) events without operator action, and without the support of active shutdown, shutdown heat removal, or any automatic system without damage to the plant and without jeopardizing public safety. 

There are a number of equipments and technologies vdiich require R D work for implementation to KALIMER. To name a few, the submerged EM pump, a seismic isolator, high temperature structures, metal friel, passive Curie point shutdown system, and a steam generator. R D work for all of these items require massive investment to the facility and it is desirable to carry out the selected R Ds through an international collaboration if possible. The international collaboration in the systems engineering and methodology development is also needed to support the domestic efforts of Korea for KALIMER development. 

These characteristics enable the plant to operate with less need for routine operator intervention or presence. It is clear from this list that the safety of such small reactors relies much more on inherent design characteristics, and (to a lesser extent) on shutdown systems, than on engineered heat removal or prompt human intervention. 

Reactor shutdown and engineered safety systems are initiated by two diverse reactor protecton systems with the safety systems arranged in four trains. 

XVII-10] KAMBE, M., Fast reactor passive shutdown system LIM, ICONE-7 (Proc. of the 7th Int. Conf on Nuclear Engineering, Tokyo, Japan, April 1999) pp. ICONE-7069. 

Accessories available for lube-oil systems are such items as flowmeters and oil-level regulators. These can be unit-mounted and automatically add oil as it is consumed as well as measure and record the quantity of oil consumed. It is also possible to obtain engine-mounted switches for low and high engine lube-oil levels to signal a warning and/or cause engine shutdown. 

Reactor shutdown is assured by two independent and diverse basic shutdown systems which guarantee very high reliability so as to relegate shutdown failure into the domain of residual risk. In the domain of residual risk, however, the "Third Shutdown Level" becomes effective. It consists of a bundle of additional engineered safety features which are incorporated in the design as a result of extensive risk-minimization studies. The system consists of active and passive subsystems and is supported by beneficial natural core behaviour. For example, the following features of the absorber rod actuators are part of the "Third Shutdown Level" ... 

Figure 1-2 shows the simplified schematic diagram of the SMART nuclear steam supply system (NSSS) and exhibits the safety systems and the primary system as well as auxiliary systems. The engineered safety systems designed to function passively on demand consist of a reactor shutdown system, passive residual heat removal system, emergency core cooling system, safeguard vessel and reactor overpressure protection system. 

Since the reactor basic shutdown and decay heat removal are passive, there is no need in dedicated engineered safety systems. 

Fuel System Oil (XJN) provides fuel for engine operation and also executes speed control and engine shutdown ... 

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