Selecting equipment is rarely straight-forward. You can run into pitfalls. It helps to know what you should be looking for . . . .
Here are four factors that you should consider in mod package development when selecting new equipment to install inside of a nuclear power plant:
- Compatibility with the environment: Can the new equipment handle the environment? Consider the surrounding heat, humidity, and pressure. Don’t forget accident conditions, which usually produce higher temperatures, pressure, and humidity than normal (depending on the area). You may need to add extra fans or supplemental cooling. This is especially important when installing state-of-the-art equipment (like touchscreen displays) in very hot or humid areas.
- Impact to the environment: how will the new equipment impact the environment? It will probably generate heat, and this is a bigger problem for areas like Control Rooms that may be maxing out the capacity of their HVAC units. Look for calculations that track incremental changes in heat loading (temperature) and combustibility (flammability). It’s best to review this information very early in the design because any limitations uncovered (such as a Control Room that has maxed out its heat load) serve as critical design inputs that will factor into the design.
- Impact to electrical systems: calculations that track incremental changes in electrical load have to be updated. Local power and lighting panels (120/208/240-volt) are usually on the bottom tier of importance. They will be fed by transformers from higher-voltage motor control centers or switchgear. In loading calculations, the transformer that supplies these downstream panels is usually assumed to be fully-loaded even if that’s not presently the case. This way, electrical calcs don’t have to be updated with every incremental addition to every power panel (though drawings like panel schedules do). But the higher you go in voltage and in importance (think safety-related systems), you can count on having to update load calculations.
- Interference concerns: is there a chance that the new equipment will interfere with the movement of some nearby equipment? For example, the spent fuel pool operating floors are usually wide-open overhead. But during refueling outages, the fuel handling machine is unparked and glides across the floor on rails. There may only be a few inches of vertical clearance from the floor to the bottom of the machine, and if you don’t consider this infrequent mode of operation you may find yourself with a design problem on your hands. The same goes for traffic. People walking by can damage equipment if they accidently kick it or trip on it. Some seemingly-abandoned areas during normal plant operation can, during an outage, become as crowded as a shopping mall on Black Friday. You may need to install extra covers to protect cables or equipment from accidental tripping or swinging tools. Someone who drops a heavy wrench on a piece of instrument tubing will probably damage the tubing. The wrench will be fine.