USE OF THE FISSION MATRIX FOR STEADY STATE AND QUASI-STATIC KINETIC MODELING OF THE TREAT REACTOR WITH TEMPERATURE FEEDBACK
Open Access
- Author:
- Pizarro-Vallejos, Alvaro
- Graduate Program:
- Nuclear Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- July 10, 2019
- Committee Members:
- William J Walters, Thesis Advisor/Co-Advisor
Azaree Tresong Lintereur, Committee Member
Arthur Thompson Motta, Committee Member - Keywords:
- Transient Test Reactor
Fission Matrix Method
Steady State Modeling
Quasi-Static Kinetic Modeling
Temperature Feedback - Abstract:
- In order to rapidly and accurately investigate the steady-state and kinetic behavior of the Transient Test Reactor (TREAT) at Idaho National Laboratories, we have coupled temperature-dependent fission matrix models to point kinetic calculations. The Monte Carlo reactor physics code Serpent is used to obtain a fission matrix that gives us the number of fission neutrons born in one core cell per fission neutrons in another cell. This fission matrix allows us to calculate two important parameters, the reactivity and neutron source distribution in each cell. Fission matrices were pre-calculated at different temperature distributions in order to develop a fission matrix database set. Given an arbitrary temperature distribution, fission matrices from this database set can be interpolated in order to estimate the fission matrix for the given distribution. This interpolation method was evaluated on several artificial temperature distributions to test the accuracy in the fission matrix eigenvalue (multiplication factor) and eigenvector (source distribution). For a realistic temperature profile, the fission matrix interpolation method gave results within 50 pcm and 40 pcm of the Serpent reference result. TREAT is typically used to perform temperature-limited transients, which deposit large amounts of energy into a central fuel testing location. Therefore, the kinetic simulation of TREAT is also important, in order to estimate the power profile and energy deposited in the test cell during transient operation. The kinetic behavior of a temperature-limited transient was modeled using point-kinetics, and by using the fission matrix with a quasi-static kinetic model. The quasi-static method accounts for the re-distribution of the power in the reactor during a transient, as opposed to the static power profile assumption of point-kinetics.