Post Irradiation Examination of HTR Fuel at ITU Karlruhe

In the last years considerable efforts have been made at the Institute for Transuranium Elements (ITU) in order to reestablish European knowledge and ability in safety testing of irradiated high temperature reactor (HTR) Fuel Elements. In the framework of the 6th European framework programme a cold finger apparatus (Ku¨FA) furnace, formerly installed at FZ-Ju¨lich (FzJ), has been installed in a hot cell at ITU [Freis 2008] in order to test fission product release under high temperature and non-oxidising conditions. Several analytical methods (e.g. Gamma-spectrometry, mass-spectrometry) have been applied in order to analyse different isotopes released during Ku¨FA tests. After the heating tests, examinations of the fuel elements were performed including scanning electron microscopy (SEM) and micro-hardness testing of coated particles. Individual coated particles were object of heating tests in a Knudsen cell with a coupled mass spectrometer measuring all released species. In order to cover more accident scenarios, a second furnace for oxidising-conditions (air- or water-ingress) was constructed and installed in a cold lab. Furthermore a disintegration apparatus, based on anodic oxidation, was constructed and fuel elements were dissolved obtaining thousands of individual coated particles for further examination. A fully automated irradiated microsphere gamma analyzer (IMGA) is under construction and will be used, in particular, to identify and sort out failed particles.

Download Full-text

Postirradiation Testing of High Temperature Reactor Spherical Fuel Elements Under Accident Conditions

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.3094020 ◽

2010 ◽

Vol 132 (4) ◽

Cited By ~ 4

Author(s):

D. Freis ◽

D. Bottomley ◽

J. Ejton ◽

W. de Weerd ◽

H. Kostecka ◽

...

Keyword(s):

High Temperature ◽

Fission Product ◽

Fission Products ◽

General Concept ◽

Cold Finger ◽

Product Release ◽

High Temperature Reactor ◽

Accident Conditions ◽

Fuel Elements ◽

Beijing China

A new furnace for accident condition testing of spherical high temperature reactor fuel elements has been installed and now operates in the hot cells of the Institute for Transuranium Elements (ITU) Karlsruhe. The recent apparatus was constructed on the basis of a former development by Forschungszentrum Jülich (Schenk, Pitzer, and Nabielek, 1988, “Fission Product Release Profiles From Spherical HTR Fuel Elements at Accident Temperatures,” Jülich Report No. 2234), where it was named KüFA, the German acronym for cold finger apparatus. In a preceding publication (Kostecka, Ejton, de Weerd, and Toscano, 2004, “Post-Irradiation Testing of HTR-Fuel Elements Under Accident Conditions, Part 1 and 2,” Second International Topical Meeting on High Temperature Reactor Technology, Beijing, China) the general concept and details of the device were described. The present paper reports on the first operation under hot conditions, and the calibration of the fission gas measurement and of the efficiency of the cold finger, which is used to plate out solid fission products. Finally the results of fission product release and analysis of two heating tests on two fuel elements from the high temperature reactor K6 irradiation experiment (Nabielek, Conrad, Roellig, and Meyers, 1993, “Fuel Irradiation Experiments on HFR-K6 and HFR-B1 With Intermittent Water Vapour Injections,” Technical Committee Meeting on Response of Fuel, Fuel Elements and Gas Cooled Reactor Cores Under Accidental Air or Water Ingress Conditions, Beijing, China, Oct. 25–27) are presented and discussed.

Download Full-text

Post Irradiation Testing of High Temperature Reactor Spherical Fuel Elements Under Accident Conditions

Fourth International Topical Meeting on High Temperature Reactor Technology, Volume 1 ◽

10.1115/htr2008-58203 ◽

2008 ◽

Cited By ~ 3

Author(s):

D. Freis ◽

D. Bottomley ◽

J. Ejton ◽

W. de Weerd ◽

H. Kostecka ◽

...

Keyword(s):

High Temperature ◽

Fission Products ◽

General Concept ◽

Cold Finger ◽

Fission Gas ◽

Accident Condition ◽

Gas Measurement ◽

High Temperature Reactor ◽

Accident Conditions ◽

Fuel Elements

A new furnace for accident condition testing of spherical High Temperature Reactor (HTR) fuel elements has been installed and is now operating in the Hot Cells of the Institute for Transuranium Elements (ITU) Karlsruhe. The recent apparatus was constructed on the basis of a former development by Forschungszentrum Ju¨lich (FzJ) [Schenk 1988] where it was named Ku¨FA, the German acronym for cold finger apparatus. In a preceding publication [Toscano 2004] the general concept and details of the device were described. The present paper reports on the first operation under hot conditions, the calibration of the fission gas measurement and of the efficiency of the cold finger, which is used to plate out solid fission products. Finally the results of fission product release and analysis of two heating tests on two fuel elements from the HFR K6 irradiation experiment [Nabielek 1993] are presented and discussed.

Download Full-text

Statistical Burnup Distribution of Moving Pebbles in the High-Temperature Reactor HTR-PM

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4044910 ◽

2020 ◽

Vol 6 (2) ◽

Author(s):

Fanny Vitullo ◽

Jiri Krepel ◽

Jarmo Kalilainen ◽

Horst-Michael Prasser ◽

Andreas Pautz

Keyword(s):

High Temperature ◽

Cross Sections ◽

Fuel Cycle ◽

Practical Method ◽

Clear Understanding ◽

Monte Carlo Code ◽

The Core ◽

High Temperature Reactor ◽

Under Construction ◽

Fuel Elements

Abstract In the pebble-bed high-temperature reactor under construction in China, called the HTR-PM, the spherical fuel elements continuously flow downward in the cylindrical core. The burnup of each pebble is checked at the core outlet and, according to the achieved burnup level, the pebble might be disposed or reinserted into the upper section of the core. Upon reinsertion, each pebble is radially distributed in a random manner and, according to its downward path, faces different burnup conditions. Hence, the number of passes necessary to achieve the average discharge burnup of 90 MWd/kgU may vary. Discrete element method (DEM) simulations have been carried out to achieve a clear understanding of the movement of the 420000 fuel pebbles in the HTR-PM core. At the same time, neutronics properties have been investigated for a single pebble and for the full core with the Serpent 2 Monte Carlo code. As a result, one-group microscopic cross sections (XS) have been parametrized at the core level. The pebble movement has been loosely coupled with the depletion of a single pebble in a dedicated burnup script called moving pebble burnup (MPB), developed in matlab. 3000 single pebble burnup histories were simulated to obtain sufficient statistics and an insight into the HTR-PM burnup process. The decrease of the average burnup gained per single pass implies that a miss-handling of recirculated fuel elements is unlikely to lead to an excess of the maximum allowed burnup of 100 MWd/kgU. The core demonstrates a self-compensation effect of burnup, meaning that it always compensates burnup under- or over-runs in the successive passes. In addition, gamma detection of 137Cs has been studied as a practical method for monitoring the burnup of the discharged pebbles, turning out to be an applicable measurement technique. Finally, it is possible to conclude that the fuel cycle of the HTR-PM, as it has been laid out, is well designed and feasible.

Download Full-text