Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2004. / Includes bibliographical references (leaf 107). / This thesis examines two methods for speeding up MCNP KCODE calculations. The first approach is assembly of a low cost Beowulf Cluster for parallel computation. The first half describes the MIT Nuclear Engineering Department's Beowulf Cluster, Echelon, as a prototype. Echelon is a low cost, 30 CPIJ, disk-less Debian Linux Beowulf Cluster. A user's manual is documented and a series of tips given on how to build a similar cluster, and a method described for optimally using the Monte Carlo N Particle (MCNP) Code on this cluster. The focus is on the complex software setup required but also touches upon hardware optimization and cost. The second method is optimization of the parallel KCODE communication algorithm in MCNP. A new patch for the parallel MCNPX KCODE communication algorithm is examined. The new patch facilitates the local execution of KCODE cycles, greatly eliminating interprocess communication. Combined with numerous minor changes to MCNPX the new patch file can speed up MCNPX KCODE calculations by an order of magnitude on a Beowulf Cluster using 60 CPUs. The conceptual design of the new algorithm and the actual changes made to the code are described including showing how an MCNPX user can take advantage of the new features in practice, and providing timing results comparing the new and old algorithms. Combined, the Echelon system and the new communication algorithm speeds up MCNP KCODE execution by 20 fold in parallel and nearly 30 fold with multiple jobs. This allows advanced criticality and complex burnup calculations that previously required a day to be done in an hour. This significant performance gain opens a whole new level of problem complexity for a relatively low cost. / by Nathan Carstens. / S.M.

Includes bibliographical references (p. 105-107). / Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2005. / Abstract The Alcator C-Mod control system was upgraded to digital architecture DPCS (Digital Plasma Control System). The main features of the digital system are the high flexibility, robustness and maintainability. The hardware consists of low-latency digitizers, a single processor Xeon server and DAC output cards. The software is a set of IDL routines. In the current version of the software, DPCS is emulating the PID controller of the previous control system Hybrid, but some advanced and adaptive features have already been implemented, for example the compensation of the input offsets. DPCS has been operating successfully since the beginning of the 2004-2005 experimental campaign. One of the advantages of a digital control system is that a simulator can be embedded in the system. We programmed a Matlab-Simulink simulator Alcasim for Alcator C-Mod. The simulator is a versatile tool to model the tokamak and the plasma, to interface with the database of the real experiments and to test new control algorithms, while running open loop and closed loop simulations. The powerful block-diagram language of Simulink allows to easily update the various components of the feedback loop, should the need arise. Preliminary results from the simulations of real shots are presented and discussed. / by Marco Ferrara. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995. / Includes bibliographical references (p. 82-84). / by Artur P. Niemczewski. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995. / Includes bibliographical references. / by Chun-Shan Yam. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1995. / Includes bibliographical references (leaves 159-163). / by Shuanghe Shi. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1996. / Includes bibliographical references (leaves 120-123). / by David Walter Fink. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1996. / Includes bibliographical references (p. 286-292). / by Paul Chodak III. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1996. / "February 1996." / Includes bibliographical references. / by Bruce A. Hilton. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1992. / Includes bibliographical references (leaves 129-131). / by Michael L. Zerkle. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1992. / Title as it appears in the Feb. 1992 MIT Graduate List: The tight-binding approximation in molecular dynamics simulation. / Includes bibliographical references (leaves 50-52). / by Ahmet Isik. / M.S.