Design options have been evaluated for the Modular Helium Reactor (MHR) for
higher temperature operation. An alternative configuration for the MHR coolant inlet
flow path is developed to reduce the peak vessel temperature (PVT). The coolant inlet
path is shifted from the annular path between reactor core barrel and vessel wall through
the permanent side reflector (PSR). The number and dimensions of coolant holes are
varied to optimize the pressure drop, the inlet velocity, and the percentage of graphite
removed from the PSR to create this inlet path. With the removal of ~10% of the
graphite from PSR the PVT is reduced from 541 0C to 421 0C.
A new design for the graphite block core has been evaluated and optimized to
reduce the inlet coolant temperature with the aim of further reduction of PVT. The
dimensions and number of fuel rods and coolant holes, and the triangular pitch have
been changed and optimized. Different packing fractions for the new core design have
been used to conserve the number of fuel particles. Thermal properties for the fuel
elements are calculated and incorporated into these analyses. The inlet temperature, mass
flow and bypass flow are optimized to limit the peak fuel temperature (PFT) within an
acceptable range.
Using both of these modifications together, the PVT is reduced to ~350 0C while
keeping the outlet temperature at 950 0C and maintaining the PFT within acceptable
limits. The vessel and fuel temperatures during low pressure conduction cooldown and high pressure conduction cooldown transients are found to be well below the design
limits.
The reliability and availability studies for coupled nuclear hydrogen production
processes based on the sulfur iodine thermochemical process and high temperature
electrolysis process have been accomplished. The fault tree models for both these
processes are developed. Using information obtained on system configuration,
component failure probability, component repair time and system operating modes and
conditions, the system reliability and availability are assessed. Required redundancies
are made to improve system reliability and to optimize the plant design for economic
performance. The failure rates and outage factors of both processes are found to be well
below the maximum acceptable range.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1354 |
| Date | 15 May 2009 |
| Creators | Reza, S.M. Mohsin |
| Contributors | Peddicord, Kenneth Lee |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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