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Title: FFTF Passive Safety Test Data for Benchmarks for New LMR Designs

Abstract

Liquid Metal Reactors (LMRs) continue to be considered as an attractive concept for advanced reactor design. Software packages such as SASSYS are being used to im-prove new LMR designs and operating characteristics. Significant cost and safety im-provements can be realized in advanced liquid metal reactor designs by emphasizing inherent or passive safety through crediting the beneficial reactivity feedbacks associ-ated with core and structural movement. This passive safety approach was adopted for the Fast Flux Test Facility (FFTF), and an experimental program was conducted to characterize the structural reactivity feedback. The FFTF passive safety testing pro-gram was developed to examine how specific design elements influenced dynamic re-activity feedback in response to a reactivity input and to demonstrate the scalability of reactivity feedback results to reactors of current interest. The U.S. Department of En-ergy, Office of Nuclear Energy Advanced Reactor Technology program is in the pro-cess of preserving, protecting, securing, and placing in electronic format information and data from the FFTF, including the core configurations and data collected during the passive safety tests. Benchmarks based on empirical data gathered during operation of the Fast Flux Test Facility (FFTF) as well as design documents and post-irradiation examination will aid in the validation ofmore » these software packages and the models and calculations they produce. Evaluation of these actual test data could provide insight to improve analytical methods which may be used to support future licensing applications for LMRs« less

Authors:
;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1344671
Report Number(s):
PNNL-SA-115515
RC0417000
DOE Contract Number:
AC05-76RL01830
Resource Type:
Conference
Resource Relation:
Conference: Physics of Reactors (PHYSOR 2016): Unifying Theory and Experiments in the 21st Century, May 1-6, 2016, Sun Valley, Idaho, 2050-2058
Country of Publication:
United States
Language:
English

Citation Formats

Wootan, David W., and Casella, Andrew M. FFTF Passive Safety Test Data for Benchmarks for New LMR Designs. United States: N. p., 2016. Web.
Wootan, David W., & Casella, Andrew M. FFTF Passive Safety Test Data for Benchmarks for New LMR Designs. United States.
Wootan, David W., and Casella, Andrew M. 2016. "FFTF Passive Safety Test Data for Benchmarks for New LMR Designs". United States. doi:.
@article{osti_1344671,
title = {FFTF Passive Safety Test Data for Benchmarks for New LMR Designs},
author = {Wootan, David W. and Casella, Andrew M.},
abstractNote = {Liquid Metal Reactors (LMRs) continue to be considered as an attractive concept for advanced reactor design. Software packages such as SASSYS are being used to im-prove new LMR designs and operating characteristics. Significant cost and safety im-provements can be realized in advanced liquid metal reactor designs by emphasizing inherent or passive safety through crediting the beneficial reactivity feedbacks associ-ated with core and structural movement. This passive safety approach was adopted for the Fast Flux Test Facility (FFTF), and an experimental program was conducted to characterize the structural reactivity feedback. The FFTF passive safety testing pro-gram was developed to examine how specific design elements influenced dynamic re-activity feedback in response to a reactivity input and to demonstrate the scalability of reactivity feedback results to reactors of current interest. The U.S. Department of En-ergy, Office of Nuclear Energy Advanced Reactor Technology program is in the pro-cess of preserving, protecting, securing, and placing in electronic format information and data from the FFTF, including the core configurations and data collected during the passive safety tests. Benchmarks based on empirical data gathered during operation of the Fast Flux Test Facility (FFTF) as well as design documents and post-irradiation examination will aid in the validation of these software packages and the models and calculations they produce. Evaluation of these actual test data could provide insight to improve analytical methods which may be used to support future licensing applications for LMRs},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 9
}

Conference:
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  • A series of tests were completed at the Fast Flux Test Facility to demonstrate the passive safety characteristics of liquid metal reactors with natural circulation flow. The first test consisted of transition from forced to natural circulation flow at an initial decay power of 0.3%. The second test represented an unprotected loss-of-flow transient to natural circulation from 50% power with the control rods prevented from scramming into the core. The third test was a steady-state, natural circulation condition with core fission powers up ato about 2.3%. Core sodium data and results of single and multi-channel computer models confirmed the reliabilitymore » and effectiveness of natural circulation flow for liquid metal reactor safety.« less
  • The FFTF is a 400-MWt sodium-cooled fast neutron flux test reactor located on the US government-owned Hanford Site in southeastern Washington state. The reactor is operated for the US Department of Energy by the Westinghouse Hanford Company. Since FFTF started routine operation in 1982, the commercially fabricated driver fuel has performed flawlessly to well beyond the design goal peak burnup of 80 MWd/kgM. The core average discharge exposure is now some 60% beyond the original design expectations and attests to the ruggedness and reliability of the mixed oxide fuel system. In Cycle 9 sixteen long-life assemblies were installed to beginmore » the irradiation of mixed oxides in the advanced low-swelling alloy HT-9 as the Core Demonstration Experiment (CDE). Operation of the plant from initial startup testing to ten cycles of operation has confirmed that the nuclear characteristics are well within the design predictions, and all parameters have remained inside the operating envelope defined by the Technical Specifications. Valuable experience has been gained in the identification and location of FFTF fuel assemblies containing a breached pin. Since the reactor began full-power operation in 1981, ten experimental fuel pin breaches have occurred and all were successfully identified. The principal objectives of the combined FFTF natural circulation and Passive Safety Testing program were: (1) to verify natural circulation as a reliable means to safely remove decay heat, (2) to extend passive safety experience to a large-size LMR and obtain data for validating design analysis computer codes, and (3) to develop and test passive safety enhancements that might be used for future LMRs.« less
  • The FFTF Loss-of-Flow-Without-Scram Test from 50% power to natural circulation flow was analyzed with the SASSYS code using both the SASSYS reactivity feedback models and the semiempirical reactivity feedback equations for the FFTF oxide-fuel core. The experimental data for primary loop flow and reactor power were used as inputs to obtain the same fuel, sodium, and structure temperatures for both sets of reactivity feedbacks. A detailed comparison was made for each of the reactivity feedbacks: Doppler, sodium density, control rod expansion, axial fuel expansion, radial expansion, and bowing. The major differences between the SASSYS reactivity models and the FFTF reactivitymore » equations were in the radial expansion and bowing feedback. The sensitivity of the results to the input for the SASSYS radial expansion and bowing model was investigated.« less
  • The presence and effectiveness of passive safety features in six recent U.S. fusion designs are reviewed, namely the Compact Ignition Tokamak (CIT), Tokamak Ignition/Burn Experimental Reactor (TIBER), Tokamak Power Systems Study (TPSS), two TITAN Reverse Field Pinch (RFP) designs, and the Advanced Safe Pool Immersed Reactor (ASPIRE). The safety assurance level for these designs range from true inherent safety to requiring active safety systems. Much progress has been made, so that most designs appear to achieve some level of passive safety, intermediate between inherent safety and needing active systems. Key factors include material choice, cooling geometry and neutron wall loading.more » Advantages in one factor can compensate for disadvantages in another. For example, with selection of a pool geometry, the neutron wall loading may be safely increased. Consideration of investment protection is included with the safety assessments but is quite limited because of the difficulty of assessing what damage can be repaired. 11 refs., 7 tabs.« less
  • The Fast Flux Test Facility has provided a very useful framework for testing the advances in Liquid Metal Reactor Safety Technology. During the licensing phase, the switch from a nonmechanistic bounding technique to the mechanistic approach was developed and implemented. During the operational phase, the consideration of new tests and core configurations led to use of the anticipated-transients-without-scram approach for beyond design basis events and the move towards passive safety. The future role of the Fast Flux Test Facility may involve additional passive safety and waste transmutation tests. 26 refs.