System shut-down

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

Ideally most oil or gas incidents will be controlled by the process shut down systems (ESD, depressurization, drainage, etc.) and hopeful the fire protection systems (fireproofing, water deluge, etc ), will not be required. However these primary fire defense systems may not be able to control fire incidents if previous explosions have previously occurred. Before any consideration of fire suppression efforts, explosion effects must first be analyzed to determine the extent of protection necessary. Most major fire incidents associated with hydrocarbon process incidents are preceded by explosion incident. 

PILOT VALVE 25 fl EMERGENCY SHUT DOWN SYSTEM... 

Hydrogen dispensers will likely make use of programmable logic controllers or PC-based control systems. Both liquid hydrogen and compressed hydrogen dispensers will need to be able to monitor pressures and temperatures, open and close valves, turn on pumps, and interface with fire and emergency shut-down systems. 

NFPA 57 recommends that LNG dispensers be protected from collisions with vehicles and that they incorporate an emergency shut-down system. The maximum delivery pressure of the dispenser shall not exceed the operating pressure of the LNG tanks on the vehicle being refueled, and the LNG delivery hoses must have a shut-off valve at the end and a breakaway valve in the event a vehicle drives off with the refueling hoses attached. Bleed and vent valve must be incorporated into the dispensing lines to allow them to be drained and depressurized prior to disconnection if necessary. 

LNG carriers are equipped with gas and fire detection systems. The cargo safety system is extensively instrumented - including a shut down system that is activated on predetermined parameters. Furthermore, the safety equipment of LNG carriers includes sophisticated radar and positioning systems that alert the crew to the surrounding traffic on potential hazards. A number of distress systems and beacons will automatically emit signals if the ship enters difficulty positions [10]. 

If an instrument or instrument system malfunctions, the operator tries to correct the problem. If an alarm, flow or temperature measuring instrument or shut down system malfunctions, the operators first response should be an attempt to restore it to service. It may be a... 

G EMERGENCY SHUT DOWN SYSTEM ESO OPERATION WHEN PILOT ... 

PILOT VALVE 25 emergency shut Down system... 

Verify safety shut down system Operations team... 

The safety system of the refinery is called AES and has been applied to units with high danger potential in addition to the usual shut down system. The AES system was developed originally for use in steam crackers and ethylene plants, and is initiated using both simultaneously pressing and turning a switch. 

Failure rates of complex equipment can often be greatly reduced through redundant arrangements. Redundancy provides multiple means of warning and shut down systems to ensure personnel and equipment are safe from failures that could result in a hazardous situation. Redundancy is based upon how critical an event is to worker safety or process continuation. Two separate switches or two separate alarms provide redundancy. In addition, there is standby redundancy. In this case, a piece of equipment operates until a failure is indicated, at which time another duplicate piece of equipment is turned on either automatically or manually. An excellent example of redundancy is fire water pumps. There are always at least two or more. A unit does not want to experience a fire, the site has only one pump, and that is the day the pump fails. 

The two reactor shut down systems which are consisted of 10 control rods and 7 small absorber ball holes are all positioned in the side reflector. The in core control rods are not needed. 

A separate shut down system could be excluded. 

Fan fuse (F3) Fuse blows Ground and Air Fan remains off DC PS overheats if DIRCMis operating DIRCM system failure indication High temperature switch will cause overtemperature indication DC PS/Mod has internal overtemperature switch which shuts down system 6x10-7 Minor... 

The reactor is equiped with two independoit shut down systems, first of which is composed of 3 compensation and 2 regulation subassonblies with a rrqiid drop down time less than 1.5 seconds, the second shut down system includes 3 safety subassemblies widi a rqrid drop down time less than 0.7 seconds. 

Research on the self-actuated shut-down system (S ASS) by using a curie point magnet is in progress. A preparation of system performance test on SASS by use of Joyo is underway. 

Sccondm Transii ts Redundant control and shut down systems/pressure relief... 

In the PHWR 220s two systems, i.e. 14 mechanical shut-off rods which fall freely under gravity into the core and 12 liquid poison stand-pipes into which sodium-penta borate solution is introduced, provide fast acting redundant and diverse shut-down systems. These are reinforced by slow-acting automatic liquid poison addition into the moderator system for prolonged shut-downs. 

The reactor shut-down system includes 6 independent control rod groups (CGs) which can be inserted into the core by electric drives or under gravity in the case of de-energization of the drives. The drives are also equipped with a special mechanism for hand-operated insertion of each CG. In addition, a liquid absorber injection system is provided. 

Reactivity control Operating control rods Diverse reserve shut down system Negative temperature coefFicient Startup control rods Active/Passive Active/Passive Passive Active(Passive Automatic activation, gravity drop Automatic activation, gravity drop Automatic activation, gravity drop... 

CCS-Cavity Cooling System, CPV-Connecting Pressure Vessel KLAK-Small absorber spheres shut down system, RB-Reactor Building RPV-Reactor Pressure Vessel, SGPV-Steam Generator Pressure Vessel StrSchV - Strahlenschutzverordnung (German Radiation Protection Ordinance)... 

There is a diverse emergency shut down system which is initiated manually if it is not possible to insert the control rods. It allows for injection of boron into the reactor. Since inadvertent operation of this system must be completely prevented, it requires insertion of a spool piece to connect the boron tank to the reactor. The negative moderator temperature coefficient is sufficient to maintain the reactor in a hot shut down condition for several days until the spool piece can be inserted. 

The reactor shut down system (RSS) is a constituent part of the CPS and is designed in such a way that a CPS failure does not affect operability of the RSS. An important feature of the reliabili of the RSS actuation is the fact that apart from 6 RSS clusters all 19 clusters of the CPS fall to their ultimate lowest position under gravity. 

Additional shutdown systems Two independent passive safety shut-down systems 24 shu-off rods and 6 liquid poison injection circuits... 

Normal shut down system (Y/N) Yes (Control rods moved in lateral reflector)... 

If an instrument or instrument system malfunctions, the operator tries to correct the problem. If an alarm, flow or temperature measuring instrument or shut down system malfunctions, the operators first response should be an attempt to restore it to service. It may be a plugged impulse line, inadvertent flow shut off to an analyzer, etc. If the Instrument System is a Class I or 2, immediately go to Step 2. If the alarm is a Class 3, the Lead Operator (or Shift Foreman) should be consulted and follow established procedures and his knowledge of the unit and the specifics of the situation to determine the temporary steps required. At the minimum, a note in the maintenance logbook must be made to initiate repairs. Stop Here for Class 3 Alarms. 

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