Release behavior of metallic fission products from HTGR fuel particles at 1600 to 1900°C

Minato, Kazuo; Ogawa, Teiichiro; Fukuda, Kousaku; Sekino, Hajime; Miyanishi, Hideyuki; Kado, Shigeo; Takahashi, Ishio

doi:10.1016/0022-3115(93)90027-v

Cited by 69 publications

(34 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Past studies have shown that Pd can corrode SiC [15][16][17] and it has been postulated to be a potential failure mechanism at high burnup in low-enriched TRISO fuels when temperatures exceed 1100°C. Characterization studies by Barrachin et al, [15] on HFR-EU1bis experiments on UO 2 TRISO fuel (10.2% FIMA, calculated pebble centre temperature of 1250°C) found that Pd is specifically present in the inner pyrocarbon layer at the inside of the SiC layer, but no Pd is mentioned in the SiC layer itself.…”

Section: Introductionmentioning

confidence: 99%

Identification of silver and palladium in irradiated TRISO coated particles of the AGR-1 experiment

Rooyen

Lillo

2014

Journal of Nuclear Materials

View full text Add to dashboard Cite

Evidence of the release of certain metallic fission products through intact tristructural isotropic (TRISO) particles has been seen for decades around the world, as well as in the recent AGR-1 experiment at the Idaho National Laboratory (INL). However, understanding the basic mechanism of transport is still lacking. This understanding is important because the TRISO coating is part of the high temperature gas-cooled reactor functional containment and critical for the safety strategy for licensing purposes.Our approach to identify fission products in irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), Electron Energy-Loss Spectroscopy (EELS) and Energy Filtered TEM (EFTEM), has led to first-of-a-kind data at the nano-scale indicating the presence of silver at triple-points and grain boundaries of the SiC layer in the TRISO particle. Cadmium was also found in the triple junctions. In this initial study, the silver was only identified in SiC grain boundaries and triple points on the edge of the SiC-IPyC interface up to a depth of approximately 0.5 μm.Palladium was identified as the main constituent of micron-sized precipitates present at the SiC grain boundaries. Additionally spherical nano-sized palladium rich precipitates were found inside the SiC grains. No silver was found in the center of the micron-sized fission product precipitates using these techniques, although silver was found on the outer edge of one of the Pd-U-Si containing precipitates which was facing the IPyC layer. Only Pd-U containing precipitates were identified in the IPyC layer and no silver was identified in the IPyC layer.The identification of silver alongside the SiC grain boundaries and the findings of Pd inside the SiC grains and alongside SiC grain boundaries provide important information needed to understand silver and palladium transport in TRISO fuel, which has been the topic of international research for the past forty years. The findings reported in this paper may support the postulations of recent research that Ag transport may be driven by grain boundary diffusion. However, more work is needed to fully understand the transport mechanisms. Additionally, the usefulness of the advanced electron microscopic techniques for TRISO coated particle research is demonstrated in this paper.

show abstract

Section: Introductionmentioning

confidence: 99%

Identification of silver and palladium in irradiated TRISO coated particles of the AGR-1 experiment

Rooyen

Lillo

2014

Journal of Nuclear Materials

View full text Add to dashboard Cite

show abstract

“…This result showed that no through-coatings-failed Fig. 5 Furnace for post-irradiation heating test 7) particle was present in the heated fuel compact.…”

Section: Post-irradiation Heating Test (1) Fuel Compact Heating Testmentioning

confidence: 83%

“…5. 7) The furnace is composed of a graphite heater, a graphite sample holder and carbon insulators within the stainless steel vessel. In this test, a fuel compact was used as sample and was heated in flowing helium.…”

Section: Post-irradiation Heating Test (1) Fuel Compact Heating Testmentioning

confidence: 99%

Integrity Confirmation Tests and Post-irradiation Test Plan of the HTTR First-Loading Fuel

Sawa¹,

Sumita²,

Ueta³

et al. 2001

Journal of Nuclear Science and Technology

Self Cite

View full text Add to dashboard Cite

Since the first-loading fuel of the High Temperature Engineering Test Reactor (HTTR) is the first mass-production High Temperature Gas-cooled Reactor (HTGR) fuel in Japan, their quality should be carefully inspected. For the quality control related to the fabrication process, Japan Atomic Energy Research Institute (JAERI) carried out the tests to certify the fuel integrity during operation. The tests comprise (1) as-fabricated SiC failure fraction measurement, (2) high-temperature heatup test of irradiated fuel and (3) accelerated irradiation test. For (1), the SiC failure fraction was measured independently in JAERI in addition to the measurement in the fabrication process. The measured failure fractions agreed within 95% confidence limit. In order to confirm the integrity of the SiC layer with respect to the 1,600• C criterion, the high-temperature heatup test of irradiated fuel compact was carried out. The result showed that no failed particle was present in the fuel compact after heating. The diffusion coefficient of metallic fission products in SiC layer was also examined in a series of post-irradiation heating tests. The measured diffusion coefficient of 137 Cs showed a good holding ability as those obtained for research and development fuel specimen. The measured fission gas release rate in accelerated irradiation test showed no additional failure up to 60 GWd/t which was about two times higher than 33 GWd/t of the maximum burnup in the HTTR core. Through the tests, integrity of as-fabricated first-loading fuel of the HTTR was finally confirmed. The future post-irradiation test plan, which will be carried out to confirm the fuel irradiation performance and to obtain the data on its irradiation characteristics in the core, is also described.

show abstract

“…SiC dan PyC berfungsi sebagai penghalang untuk lepasnya sebagian besar produk fisi baik gas maupun logam. Selain itu lapisan SiC bertindak sebagai penghalang primer terhadap lepasnya produk fisi logam karena koefisien difusi dan kelarutan produk fisi logam dalam lapisan SiC relatif rendah [16].…”

Section: B Kinerja Penghalang/barrierunclassified

Analisis Kinerja Bahan Bakar Reaktor Tipe HTGR Sebagai Penghalang Produk Fisi

Dewita¹,

Alimah²

2017

Jurnal Pengembangan Energi Nuklir

View full text Add to dashboard Cite

ANALISIS KINERJA BAHAN BAKAR REAKTOR TIPE HTGR SEBAGAI PENGHALANG PRODUK FISI.Reaktor tipe HTGR merupakan reaktor berpendingin gas temperatur tinggi (~ 900 o C). Terdapat 2 tipe elemen bakar HTGR yaitu prismatik dan pebble bed. Kedua tipe elemen bakar tersebut tersusun dari partikel berlapis TRISO yang terdiri dari lapisan IPyC, SiC dan OPyC yang berfungsi sebagai pengungkung produk fisi dan menjaga integritas bahan bakar. Reaktor beroperasi dengan temperatur tinggi, sehingga kinerja/ kemampuan bahan bakar dalam menahan produk fisi perlu diketahui. Tujuan studi adalah untuk memperoleh pemahaman tentang karakteristik produk fisi yang dihasilkan bahan bakar, karakteristik penghalang dan kinerja bahan bakar dalam menahan produk fisi. Metode yang digunakan adalah kajian dan analisis dengan mengevaluasi kemampuan penghalang (barrier) dalam menahan produk fisi pada elemen bakar prismatik dan pebble. Hasil studi menunjukkan bahwa terdapat beberapa mekanisme potensial lepasnya produk fisi, yaitu: difusi melalui lapisan, kerusakan lapisan, korosi SiC oleh produk fisi palladium dan dekomposisi termal SiC. Bahan bakar merupakan penghalang pertama terhadap lepasnya radionuklida produk fisi sedangkan lapisan SiC merupakan penghalang utama yang menahan sebagian besar produk fisi gas dan padat pada temperatur operasi normal (< 1250°C 239 Pu. Di antara produk fisi tersebut, paladium (Pd) yang lepas dari kernel dan mencapai lapisan SiC dapat bereaksi dan menyebabkan korosi. Berdasarkan hal itu, untuk menjaga integritas bahan bakar harus dilakukan pembatasan kondisi operasi reaktor, seperti: temperatur, derajat bakar, energi aktivasi produk fisi dan kualitas bahan bakar. Pada bahan bakar tipe prismatik, terdapat 8 penghalang, yaitu: kernel bahan bakar, lapisan SiC dan PyC, matriks grafit, kompak (pil) bahan bakar, sleeve grafit, sirkuit primer, blok grafit heksagonal dan bangunan reaktor. Sedangkan pada bahan bakar pebble terdapat 6 penghalang, yaitu kernel bahan bakar, lapisan SiC dan PyC, matriks grafit, lapisan grafit sebelah luar, sirkuit primer dan bangunan reaktor. Namun, jumlah penghalang bukan merupakan satu-satunya faktor yang menentukan adanya kemungkinan lepasnya produk fisi ke lingkungan. ABSTRACT ANALYSIS FOR HTGR TIPE REACTOR FUEL PERFORMANCE AS THE BARRIER PRODUCT FISSION. HTGR tipe reactor is gas cooled reactor with high outlet temperature (~ 900 o C). There are 2 types of HTGR fuel elements, prismatic and pebble bed. Both types of fuel elements composed of TRISO-coated particles are composed of layers IPyC, SiC and OPyC which serves as a confinement of fission products and maintain the integrity of the fuel. The reactor has high operating temperature, so fuel performance in retaining of fission products need to be understand. The purpose ofthe studyis to obtainan understanding of the essential characteristics of fission products produced in the HTGR fuel, fission product barrier characteristics and fuel performance in retaining fission products. The method used is the study and analysis by evaluating capabiliti...

show abstract

Release behavior of metallic fission products from HTGR fuel particles at 1600 to 1900°C

Cited by 69 publications

References 12 publications

Identification of silver and palladium in irradiated TRISO coated particles of the AGR-1 experiment

Identification of silver and palladium in irradiated TRISO coated particles of the AGR-1 experiment

Integrity Confirmation Tests and Post-irradiation Test Plan of the HTTR First-Loading Fuel

Analisis Kinerja Bahan Bakar Reaktor Tipe HTGR Sebagai Penghalang Produk Fisi

Contact Info

Product

Resources

About