Investigations of Rod Positions for Treat M8CAL Analyses

[+] Author and Article Information
Zachary Weems

Nuclear Engineering Program,
University of Florida,
3230 Innovation Blvd Room 1421, K8-34,
Richland, WA 99354
e-mail: weems1@ufl.edu

Sedat Goluoglu

Nuclear Engineering Program,
University of Florida,
549 Gale Lemerand Dr,
Gainesville, FL 32611-6400
e-mail: goluoglu@mse.ufl.edu

Mark D. DeHart

Idaho National Laboratory,
Reactor Physics Design and Analysis Department,
2525 North Freemont St.,
Idaho Falls, ID 83415
e-mail: mark.dehart@inl.gov

1Corresponding author.

Manuscript received July 24, 2017; final manuscript received December 7, 2017; published online May 16, 2018. Assoc. Editor: Dmitry Paramonov.The United States Government retains, and by accepting the article for publication, the publisher acknowledges that the United States Government retains, a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States Government purposes.

ASME J of Nuclear Rad Sci 4(3), 031017 (May 16, 2018) (7 pages) Paper No: NERS-17-1071; doi: 10.1115/1.4038929 History: Received July 24, 2017; Revised December 07, 2017

The transient reactor test facility (TREAT), a graphite moderated experimental reactor, is scheduled to restart in late 2017. There is now renewed interest in development of capabilities to model and simulate the TREAT transients using three-dimensional coupled physics. To validate existing transient analysis tools as well as those under development, several temperature-limited transients have been modeled and analyzed. These transients are from the M8 calibration (M8CAL) experiment series, a set of experiments performed to calibrate the reactor detectors for the planned M8 series of fuel tests. Detailed reactor models were prepared that were then used to calculate the pretransient and post-transient keff values as well as corresponding reactivity insertions. Alterations to modeled values of shutdown and initial transient rod insertion depths were made to better match the reported experimental values of reactivity insertions assuming just critical pretransient states. It was found that two of the altered media inputs, fuel and Zircaloy-3 cladding, had significant effects on the keff. In addition, increasing shutdown rod insertion by 3–5 cm and decreasing initial transient rod insertion by 1–2 cm gave perfect pretransient keff and total reactivity insertion values. However, the revised positions are as much as a factor of 3–20 different from reported uncertainty of 0.762 cm. This suggests that boron concentration uncertainties may play a significant role in accurately modeling the TREAT transients and should be investigated thoroughly.

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Grahic Jump Location
Fig. 1

A typical fuel element in the TREAT reactor. Fuel consists of cuboids chamfered into octagonal prisms, with long graphite pieces on either end. Cladding is octagonal as well. Taken from Ref. [1].

Grahic Jump Location
Fig. 2

A depiction of the whole TREAT core and external machinery. Taken from Ref. [1].

Grahic Jump Location
Fig. 3

A two-dimensional depiction of M8CAL half-slotted layout, with atypical elements numbered greater than 1000 and given altered color

Grahic Jump Location
Fig. 4

The TREAT core as modeled in KENO-VI, with one quarter and some outer graphite removed for viewing




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