Hot-leg piping design

Figure 11.7 Power spectrum densities for hot-leg piping design.

Analytical models, both simple and complex, would have been utilized to further develop the internally insulated Mi-base superalloy hot leg piping design. These models would have then been qualified with experimental data, as descnbed in Section 9 4.6 3 4... 

In the internally insulated, nickel superalloy hot leg piping design, the temperature of the gas inside the hot leg is 1150 K (Section 2) with the outer surface insulated to 900 K (Reference 10- 28). The primary cold leg coolant return pipe is 891 K (Section 2). 

Detailed vibration data were also accumulated from the water experiment with the stainless steel pipe. With the accumulated data, conservative design power spectmm density for stress analysis on random vibration has been defined as is shown in Fig. 11.7. Random vibration in the hot-leg piping has been analyzed, and the maximum stress is evaluated to be lower than the criteria of high cycle fatigue stress. 

Another consideration is that the reactor Met piping operates at approximately 900K. It may be advantageous to design the hot leg piping and reactor Met piping to operate at or near the same temperature to Mnimize potential issues related to differential thermal expansion of these two piping sections. 

In order for the internally insulated hot leg piping concept to have adequately performed hydraulically, thermally, and structurally, appropriate materials would need to have been selected In addition, the chosen materials would need to have met all system requirements and constraints. Final selection of the reactor plant materials would not have occurred for several years due to radiation testing and other long term materials testing however, preliminary material selection would have been required in the near term to support conceptual design and proof of principal testing. Material development efforts would have been required for the outer pipe, insulation, and liner. 

Number of Shield Penetrations for piping Does ru)t include control drive mechanism penetration or instrumentation wiring. Assumed one hot leg pipe and one cold leg pipe, for limiting shield penetration and radiation streaming. Space Reactor Shield Design Summary (SPP-67210-0011). 

NR SSA WEEvers E 05-03086, Space Power Program - Recommendation to Pursue Design Development of Internally Insulated Pipe for the Hot Leg Piping Portions of the Plant - Approval with Comments, Dated August 15, 2005. 

RHR suction line is used as SIS hot leg injection. This approach is made possible because SIS hot injection is manually actuated after 90 minutes in case of a loss of coolant accident to avoid boron crystallization. With such a design, a big pipe and its associated valves together with the injection nozzle could be deleted. This contributes to a certain gain in safety (reduction of the number of nozzles on the primary coolant lines) and in investment costs. 

Hot leg sodium is transported in separate stainless steel pipes from the two IHXs to the SG top head through vertical inlet nozzles. The cold leg piping returns the sodium to the IHX. Two EM pumps, located in the SG facility, transport the sodium through the IHTS loops. The pump design is similar to the primary system pumps. 

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