Failure Thresholds of High Burnup BWR Fuel Rods under RIA Conditions

Nakamura, Takehiko; Fuketa, Toyoshi; Sugiyama, Tomoyuki; Sasajima, Hideo

doi:10.3327/jnst.41.37

Cited by 20 publications

(23 citation statements)

References 8 publications

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“…The tested PWR fuels 1) include different design, 14Â14 and 17Â17, and variety of cladding, Zircaloy-4, low tin Zircaloy-4, ZIRLOÔ, MDA and NDA, and different grain sizes of fuel pellets. Sixteen tests with BWR fuels 2) were also conducted in burnup of 26 to 61 MWd/kgU. In the both of PWR and BWR fuel experiments, we observed cladding failure and subsequent fuel fragmentation and mechanical energy generation.…”

Section: Introductionmentioning

confidence: 91%

Behavior of 60 to 78MWd/kgU PWR Fuels under Reactivity-Initiated Accident Conditions

Fuketa

Sugiyama

Nagase

2006

Journal of Nuclear Science and Technology

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To provide a data base for the regulatory guide of light water reactors, behavior of reactor fuels during off-normal and postulated accident conditions such as reactivity-initiated accident (RIA) is being studied in the Nuclear Safety Research Reactor (NSRR) program of the Japan Atomic Energy Agency (JAEA). The paper presents recent results obtained from the NSRR power burst experiments with high burnup fuels, and discusses effects of pellet expansion as PCMI (Pellet-Cladding Mechanical Interaction) loading and cladding embrittlement primarily due to hydrogen absorption. Results from the recent four experiments on high burnup (about 60 to 78 MWd/kgU) PWR UO 2 rods with advanced cladding alloys showed that the fuel rods with improved corrosion resistance have larger safety margin against the PCMI failure than conventional Zircaloy-4 rods. The tests also suggested that the smaller inventory of inter-granular gas in the pellets with the large grain could reduce the fission gas release during the RIA transient; and high burnup structure in pellet periphery (so-called rim structure) does not have strong effect on reduction of the failure threshold because the PCMI load is produced primarily by solid thermal expansion.

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Section: Introductionmentioning

confidence: 91%

Behavior of 60 to 78MWd/kgU PWR Fuels under Reactivity-Initiated Accident Conditions

Fuketa

Sugiyama

Nagase

2006

Journal of Nuclear Science and Technology

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“…The peak fuel enthalpy ranged from 155 to 600 J/g in the PWR fuel [1][2][3][4] and from 272 to 607 J/g in the BWR fuel tests. [6][7][8][9] Fuel failure occurred in the tests HBO-1, HBO-5, TK-2, TK-7, OI-11, FK-6, FK-7, FK-9, FK-10, and FK-12.…”

Section: Pulse Irradiationmentioning

confidence: 99%

“…Details of the examination results are reported elsewhere. [1][2][3][4][6][7][8][9] The rod puncture test was performed in order to sample the released fission gas and evaluate the FGR during the pulse irradiation. Volume ratios of the sampled gas and isotopic compositions were analyzed by means of a gas chromatograph (Shimadzu Co., Ltd./CG-14B) and a mass spectrometer (Shimadzu Co., Ltd./CGMS-QP300EX), particularly to measure the concentrations of xenon (Xe) and krypton (Kr) in the sampled gas.…”

Section: Rod Puncturementioning

confidence: 99%

“…In the highburnup region, it is considered that the main cause of fuel failure under RIA conditions is the pellet-cladding mechanical interaction (PCMI): the cladding is embrittled due to hydrogen absorption following cladding oxidation, and the embrittled cladding fails following the rapid thermal expansion of the fuel pellet during the pulse irradiation. [1][2][3][4][5][6][7][8][9][10][11][12] On the other hand, new types of cladding that have improved properties against the oxidation and hydrogen absorption of cladding have been developed. Since it is considered that the brittleness due to hydrogen absorption is reduced in these claddings, it is likely that the effect of the fission gas that accumulated in the fuel pellet plays an important role in the fuel failure under RIA conditions in addition to the thermal expansion of the fuel pellet.…”

Section: Introductionmentioning

confidence: 99%

“…The test fuel segments in the FK test series were fabricated from 8 Â 8-type BWR fuels irradiated to 41-61 GWd/t in unit 3 of the Fukushima Dai-ichi NPP and unit 2 of the Fukushima Dai-ni NPP of Tokyo Electric Power Company. [6][7][8][9] The FGRs during the base irradiations were evaluated as 0.35-1.5% for the FK-1 to FK-3 fuels and 10.0-14.2% for the FK-4 to FK-12 fuels. Figure 1 shows the schematic drawings of the test fuel segment and test capsule.…”

Section: Introductionmentioning

confidence: 99%

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Identification of Radial Position of Fission Gas Release in High-Burnup Fuel Pellets under RIA Conditions

Sasajima

Sugiyama

Chuto

et al. 2010

Journal of Nuclear Science and Technology

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The radial positions of fission gas release (FGR) in high-burnup fuel pellets were examined after pulse irradiations that simulated reactivity-initiated accident (RIA) conditions in the Nuclear Safety Research Reactor (NSRR). The molar ratio of xenon (Xe) to krypton (Kr) (Xe/Kr ratio) in the released gas showed that fission gas was released from the entire region of the pellets of the examined PWR fuels during the pulse irradiations. On the other hand, most fission gas was released from the center and/or intermediate regions of the examined BWR fuel pellets. The analyses of the thermal stress distribution in fuel pellets during the pulse irradiations were carried out by means of a computer code, and the results supported the FGR positions that were estimated from the measured Xe/Kr ratios. Consequently, it is likely that fission gas is not released selectively from the rim structure at the pellet periphery under RIA conditions.

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