Improvement of Evaluation Method for Initiating-Phase Energetics Based on CABRI-1 In-Pile Experiments

Nonaka, Nobuyuki; Sato, Ikken

doi:10.13182/nt92-a34650

Cited by 26 publications

(11 citation statements)

References 1 publication

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“…Condition (4) rules out instantaneous explosive vaporization upon contact, 6) Condition (5) rules out sodium reentry, 13) and Condition (6) eliminates significant coolant entrapment as the fuel displaces the coolant. 14) These general characteristics are consistent with experimental observations [10][11][12][13] and are especially important in ruling out energetic recriticality events, i.e., eliminating the potential for reaching super prompt critical conditions from fuel compaction mechanisms driven by fuel coolant interactions between dispersed fuel and liquid sodium near the top and bottom of the active core. Condition (7) prevents significant in-core direct fuel coolant contact, i.e., the fuel and the coolant within the core is largely separated by solid cladding.…”

Section: Subassembly Blockage Potentialsupporting

confidence: 79%

“…9) Posttest examinations of numerous inpile fuel disruption tests for both fresh fuel and pre-irradiated fuel have shown extensive mixing of solidified steel within solidified fuel remains. [10][11][12] The general character of the fuel remains from all the loss-of-flow simulation tests resembles that of a porous mass of fuel with fairly large voids and with considerable entrainment of globules of steel. The resulting vaporization of entrapped steel drove fuel debris to the ends of the fuel region, i.e.…”

Section: The Role and Application Of General Behavior Princeiplesmentioning

confidence: 99%

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Assessment of the FBR Core Disruptive Accident (CDA): The Role and Application of General Behavior Principles (GBPs).

Fauske¹,

Koyama²,

Kubo

2002

J. Nucl. Sci. Technol.

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General behavior principles (GBPs) first introduced in 1976 (H. K. Fauske, the Role of Core-Disruptive Accidents in Design and Licensing of LMFBRs, Nuclear Safety, Vol. 17, No. 5, 550-567, 1976) are applied to assess the core disruptive accident (CDA) outcome for a large (3,500 MWt) high power density oxide-fueled sodium-cooled fast breeder reactor (FBR). Non-energetic termination in the so-called Initiating Phase is emphasized and is made possible by considering departures from the traditional core design including the Subassembly Inner Duct and Limited Blanket Removal concepts. This early accident scenario termination eliminates potential concerns raised related to recriticality events and also facilitates the potential for in-vessel fuel debris coolability for the large FBR with a compact reactor vessel.

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Section: Subassembly Blockage Potentialsupporting

confidence: 79%

Section: The Role and Application Of General Behavior Princeiplesmentioning

confidence: 99%

Assessment of the FBR Core Disruptive Accident (CDA): The Role and Application of General Behavior Principles (GBPs).

Fauske¹,

Koyama²,

Kubo

2002

J. Nucl. Sci. Technol.

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“…It should be noted that this difference in the postfailure responses could also be due to the difference in the pressure loss of ejected fuel/fission-gas mixture through the failure rip, and such pressure loss will be sensitive to the failure-rip condition. Figure 5 presents fuel-melting boundaries calculated with PHYSURAC 2) and PAPAS-2S 12,13) codes for the BCF1 and E12 tests at the observed failure time. PHYSURAC and PAPAS-2S codes have been developed independently in IRSN and JAEA, respectively.…”

Section: Bcf1 Test With a High-smear-density Fuelmentioning

confidence: 99%

Fuel Pin Behavior under Slow-Ramp-type Transient-Overpower Conditions in the CABRI-FAST Experiments

Fukano

Onoda

Sato

et al. 2009

Journal of Nuclear Science and Technology

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In the CABRI-FAST experimental program, four in-pile tests were performed with slow-power-ramptype transient-overpower conditions (called hereafter as ''slow TOP'') to study transient fuel pin behavior under inadvertent control-rod-withdrawal-type events in liquid-metal-cooled fast breeder reactors. The slow TOP test with a preirradiated solid-pellet fuel pin under a power ramp rate of approximately 3%Po/s was realized as a comparatory test against an existing test in the CABRI-2 program where approximately 1%Po/s was adopted with the same type of fuel pin. In spite of the different power ramp rates, the evaluated fuel thermal conditions at the observed failure time are quite similar. Three slow TOP tests with the preirradiated annular fuel resulted in no pin failure showing a high failure threshold. Based on posttest examination data and a theoretical evaluation, it was concluded that intrapin free spaces, such as central hole, macroscopic cracks, and fuel-cladding gap, effectively mitigated the fuel cladding mechanical interaction. It was also clarified that cavity pressurization became effective only in the case of a very large amount of fuel melting. These CABRI-FAST slow TOP tests, in combination with the existing CABRI and TREAT tests, provided an extended slow TOP test database under various fuel and transient conditions.

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“…Although there was no experimental knowledge of the dispersion velocity of the MN fuel, we have assumed the same velocity as in the early dispersion case of the CABRI experiments BI2 and BI3 conducted for the MOX fuel 18) because of the following considerations:…”

Section: Analytical Model Of the Fuel Disruption (1) Multichannel Modelmentioning

confidence: 99%

“…Fuel dispersion velocity, in the sodium-voided channel in the ARGO calculation system, was assumed to be À3 m/s based on the CABRI-BI3 experiments where the dominant driving force was fission gas. 18) In the case of MN fuel, however, the fuel dispersion should be driven by both the FP gas and dissociated nitrogen gas released from the molten fuel. This assumption where only the fission gas was available gives a conservative ULOF consequence due to the delayed insertion of the negative reactivity without the nitrogen gas expansion effect.…”

Section: Analytical Model Of the Fuel Disruption (1) Multichannel Modelmentioning

confidence: 99%

On Void Reactivity Limitation for the Core Loaded with Mixed Nitride Fuels

Ishizu

Endô

Ninokata

2009

Journal of Nuclear Science and Technology

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Self-controllability and self-terminability are strongly required as passive safety features in future liquid-metal FBR (LMFBR) commercialization. In this study, the self-terminability of the MN-fueled core was focused on. The FBR cores including the MN-fueled core should be designed to eliminate severe recriticality leading to energetics during core disruptive accidents (CDAs) because the cores are not designed to operate in an optimum configuration from a reactivity point of view. In addition, in the case of the MN-fueled core, the nitrogen gas N 2 generated by the thermal dissociation, one of the unique phenomena of the nitride fuel, would give another cause of reactor vessel failure. Such a mechanical effect would strongly depend on the magnitude of the void reactivity. In this study, the allowable maximum void reactivity of the MN-fueled core to maintain the mechanical integrity of the reactor vessel was evaluated against an Unprotected Loss-of-Flow (ULOF) accident by using ARGO taking into account the equation-of-state of the MN fuel. By considering the partial-pressure-dependent thermal dissociation process, the design limit of the core void reactivity (positive sum) was estimated to be 6.2 $.

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Improvement of Evaluation Method for Initiating-Phase Energetics Based on CABRI-1 In-Pile Experiments

Cited by 26 publications

References 1 publication

Assessment of the FBR Core Disruptive Accident (CDA): The Role and Application of General Behavior Principles (GBPs).

Assessment of the FBR Core Disruptive Accident (CDA): The Role and Application of General Behavior Principles (GBPs).

Fuel Pin Behavior under Slow-Ramp-type Transient-Overpower Conditions in the CABRI-FAST Experiments

On Void Reactivity Limitation for the Core Loaded with Mixed Nitride Fuels

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