Floor valve

After reactor shutdown, the refueling plug in the reactor vessel lid is removed from the fuel transfer port and an adapter and floor valve are installed on the port. The control rod drive shafts are also discoimected, and the instrument trees are moved to their stored positions. The CLEM then picks up the CCP (with the fresh-fuel assembly) from the interim decay storage vessel, transports it to tiie reactor, and lowers it into the reactor through a fuel transfer port. 

Before reactor startup, the IVHMs are placed in their stored positions in the reactor. The instrument trees and eontrol rod shafts are restored to power-operation status, the adapter and floor valve are removed, and the fuel transfer port is sealed with its plug. 

Reactor refueling systems. A series of systems associated with the reactor and reactor vessel are required for refueling. Outside the reactor vessel these include three fuel transfer ports, eight test position spool pieces, two floor valve ad ters and the test transfer port, and the reactor containment building cranes. Inside the reactor vessel are three in-vessel handling machines (IVHMs) and three invessel storage modules. Three IVHMs are required because of the mission of the FFTF that requires closed test loops in the reactor core which interfere with direct access to die entire core with one machine. 

The CLEM then picks up the CCP, containing the SNF assembly, and transfers it to the interim decay storage vessel. The cyclic process of moving fresh fuel to the reactor core and SNF back to the interim decay storage vessel continues until all the refueling operations have been completed. Before reactor startup, the IVHMs are placed in their stored positions in the reactor, the instrument trees and control rod shafts are restored to power-operation status, the adapters and floor valves are removed, and the fuel transfer ports are sealed with their plugs. 

The confinement of fission gases and contaminants, avoidance of sodium vapors in the containment building, and avoidance of air with moisture in the gas space above the sodium are of critical importance during all phases of fuel handling. Gaining access to all the inerted or potentially contaminated facilities requires the use of equipment such as floor valves (Fig. A.5) and adapters that are unique to the particular facility or port involved. The most important adapters are the two floor valve adapters and the test transfer port. 

Electrical and instrumentation coimections are also made at each refueling station to control and monitor the operation of the floor valve and provide the interlock connections to ensure safe operation (e.g., CLEM and the IVHM are interlocked at the reactor to prevent simultaneous operation in their common operating space). 

The major subassemblies of the CLEM include the grapple drive system, cask body modules, service platforms, a movable closure valve that mates with the floor valve, the cold-wall assembly, and a seal monitoring system. It also has a variety of special features for other required test-reactor operations such as moving test assemblies from the closed loops to the examination cell and assisting of the disassembly of the fuel within the cell. 

Refuelling accidents inside the containment Drop of a fuel element Crane inpact on fuel assembly head Inadvertent floor valve opening Leak in fuel transfer celFchamber. 

Overfill drum due Calibrate weighing devices and maintain equip-to operator error ment in good working order or valve failure,. metering pumps can lead to opera- tor exposure, slip- fill operation with weighing device pery floors, spread of flammable liquids. CCPS G-3 CCPS G-15 CCPS G-22 CCPS G-29... 

Today the most important applications are in surface coatings, including some use as French polish, as adhesives and cements, including valve capping and optical cements, for playing card finishes and for floor polishes. The material also continues to be used for hat stiffening and in the manufacture of sealing wax. 

Trays operate within a hydraulic envelope. At excessively high vapor rates, liquid is carried upward from one tray to the next (essentially back mixing the liquid phase in the tower). For valve trays and sieve trays,. i capacity limit can be reached at low vapor rates when liquid falls through the rray floor rather than being forced across the active area into tlic downcomers. Because the liquid does not flow across the trays, it rass.scs contact with the vapor, and the separation efficiency drops dramatically. ... 

Started. Since pump A and its associated pipework was off-line, the supervisor took the opportunity to carry out scheduled maintenance on the pressure relief valve (PRV) downstream of pump A. The valve had been malfunctioning, and although the work was not scheduled to be done for some weeks, the specialist contractor team who maintain the PRVs had a team available to carry out the work immediately. The supervisor therefore now had two teams working on the pump A systems the shift maintenance team working on the pump itself, and a two-man contractor team working on the PRV and its associated pipework. The PRV for pump A is not located immediately adjacent to the pump, and is above floor level, close to a number of other pipe runs. The following description represents a hypothetical sequence of events based on the inquiry findings, but embellished for the purposes of the case study. 

The main aspect of the job of the top floor person is to pump solvents or oil to various reactors and blenders. Instructions are issued on a job-card or by phone. The instructions are entered in a log book (which is kept by the top floor worker) and on a record card which has to be returned to the laboratory at the end of the shift. To prepare for pumping, protective clothing must be worn. After the required amoimt of solvent is set on the meter, the worker has to connect the meter and the pipeline with a hose and then open the valve on the pipeline (see Figure 7.10). Before starting the pump, the blender valve... 

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