Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ishida, Koichi; Maeda, Shigetaka; Saikawa, Takuya*; Masui, Tomohiko*
JNC TN9400 2002-005, 68 Pages, 2002/03
JNC-TN9400-2002-005.pdf:2.14MB
It is essential to evaluate the radiation damage of core structure materials used for core support plate and reactor vessel to maintain the safe operation of nuclear reactor plant. Therefore, surveillance tests for the irradiated specimen have been conducted in the experimental fast reactor JOYO to assure the integrity and to evaluate the life time. Neutron fluence and related spectral information are key palameters in evaluation of irradiation effects on the mechanical properties. They are usually predicted based on the calculation using the DORT two-dimensional transport code. In order to evaluate the calculation accuracy, the surveillance irradiation rigs (SVIRs) with dosimeter sets and gradient-monitor to monitor neutron fluences and temperatures were loaded several positions of the JOYO MK-II core. They were irradiated between 34
and 35 cycle. Based on the verification, the JOYO neutron field was precisely characterized and the calculated neutron flux at the positions of irradiated specimen and those of the core structure components need to be evaluated were corrected based on the experiments. As a result of this study, the following items are concluded: (1)The maximum fast neutron fluence (E
0.1Mev) on surveillance test specimen is determined as 2.07
10
n/cm
at 9th row of the core. (2)The neutron fluences at the positions of surveillance test specimen were higher than those of the core structure components. (3)For the core support plate which seems to be most critical for JOYO life time, the fast neutron fluence at present is 9.3810
n/cm and will reach 2.3110
n/cm at the end of life. The fast neutron fluence of reactor vessel is 3.1210
n/cm at present and will reach 4.8310n/cm at the end of life.
; Saikawa, Takuya*; Masui, Tomohiko*; Arima, Toshihiro*
JNC TN9410 2001-014, 26 Pages, 2001/03
JNC-TN9410-2001-014.pdf:0.56MB
The experimental fast reactor "JOYO" served as the MK-II irradiation test bed core for testing fuel and material for FBR development for 18 years from 1982 to 2000. "JOYO" has no fuel failure since the initial criticality. Impurity concentrations of fission products data were accumulated in the primary argon gas and primary sodium during the MK-II core operation in order to obtain background value. 352 samples of primaly argon gas and the online gamma-ray monitor determined the fission products concentration data in the primary argon gas. In order to demonstrate the performance of the cold trap pre-filter, the cold trap pre-filter function confirmation tests were carried out in 1995 during 10 annual inspection. The 
Cs concentration data in the primary sodium were determined by 10 samples of primary sodium. The in core tag gas release tests were carried out during 29th cycle to 31st cycle. The online gamma-ray monitor determined the activation tag gas concentration data in the primary argon gas These fission products concentration data, the cold trap pre-filter function confirmation tests data and in core tag gas release tests data were compiled, which were recorded on CD-ROM for user convenience.
Maeda, Shigetaka; Saikawa, Takuya*; Aoyama, Takafumi
JNC TN9410 2001-005, 219 Pages, 2001/03
JNC-TN9410-2001-005.pdf:4.92MB
Neutron fluence and related spectral information are key parameters in post-irradiation test analysis so they need to be evaluated accuracy. Nuclear calculations and a number of reactor dosimetry tests have been conducted in the JOYO experimental fast reactor to assure reliable and accurate neutron fluence for fuel and material irradiation tests. This paper describes the multiple activation foil dosimetry technique for neutron fluence evaluation. Neutron fluence was determined with neutron spectrum adjustment using measured reaction rates of a set of activation foils. Dosimetry results from individual fuel and material irradiation tests and a surveillance test characterized the neutron field of the JOYO MK-II core. Neutron flux in the JOYO core region was calculated using diffusion theory in a three-dimensional Hex-Z geometry. Flux in the stainless steel reflector region, which is outside the core, was calculated using the DORT two-dimensional transport calculation code. It is essential to correct the dosimetry results for locations far outside the core region. With corrected values, the calculated to experimental value (C/E) was approximately 1.05 in the core region and 1.1
1.5 in the reflector region.
; ; Saikawa, Takuya*; Sukegawa, Kazuya*
JNC TN9410 2000-008, 66 Pages, 2000/03
JNC-TN9410-2000-008.pdf:1.39MB
The experimental fast reactor "JOYO" served as the MK-II irradiation bed core for testing fuel and material for FBR development for 15 years from 1982 to 1997. During the MK-II operation, impurities concentrations in the sodium and the argon gas were determined by 67 samples of primary sodium, 81 samples of secondary sodium, 75 samples of primary argon gas, 89 samples of secondary argon gas (the overflow tank) and 89 samples of secondary argon gas (the dump tank). The sodium and the argon gas purity control data were accumulated from in thirty-one duty operations, thirteen special test operations and eight annual inspections. These purity control results and related plant data were compiled into database, which were recorded on CD-ROM for user convenience. Purity control data include concentration of oxygen, carbon, hydrogen, nitrogen, chlorine, iron, nickel and chromium in sodium, concentration of oxygen, hydrogen, nitrogen, carbon monoxide, carbon dioxide, methane and helium in argon gas with the reactor condition.
Ito, Chikara; Aoyama, Takafumi; Masui, Tomohiko*; Saikawa, Takuya*
JNC TN9400 99-029, 26 Pages, 1999/03
The material dosimetry using the multiple foil activation method has been carried out in order to assure the accuracy and reliability of neutron fluences for the irradiation tests in the experimental fast reactor "JOYO". In this study, the neutron fluences were calculated by the JOYO core management code system "MAGI" for the subassemblies which were irradiated at the positions around control rods or reflector boundary in the JOYO Mk-II core. Improvement of neutron fluence was evaluated when the "MAGI" calculation was corrected with the dosimetry results. The difference of the neutron spectrum adjustment was also investigated between ENDF/B-V and JENDL-3 dosimetry files. The major results obtained are summarized as follows; (1)The reaction rates of the dosimeters calculated by the adjusted neutron spectrum agreed well with the measured values, and its error was reduced. (2)The neutron spectrum adjusted using JENDL-3 dosimetry file was significantly improved than that by ENDF/B-V in the energy range of 10100 keV, because of the less error of the neutron capture cross sections of Co and Sc. (3)It showed that the correction rate of the "MAGI" calculation by the dosimetry results ranged 1030% for the subassemblies of the JOYO irradiation test.
Aoyama, Takafumi; *; Sumino, Kozo; Saikawa, Takuya*
PNC TN9410 98-004, 74 Pages, 1997/12
The Corrosion Product (CP) is the major radiation source in the primary cooling system of an LNFBR plant. It is important to characterize and predict the CP behavior to reduce the personnel exposure dose due to CP deposition. The CP measurement was carried out in the Experimental Fast Reactor JOYO during the 11th annual inspection period when the accumulated reactor thermal power reached about l43GWd. The CP deposition density was measured using a pure germanium detector. The plastic scintillation fiber (PSF) was applied for the gamma-ray dose rate distri bution measurement and compared with the thermoluminescence dosimeter (TLD). The major results obtained by the CP measurements in JOYO are the follows: (1)The major CP nuclides deposited in the primary cooling system are 
Mn and 
CO. Mn is the dominant isotope and it tends to deposit in the cold leg region. On the other hand, Co deposits mainly in the hot leg region. The deposition density of Mn is about seven times as much as that of Co in the cold leg region and twice in the hot leg region. (2)The deposition densities of Mn and Co, and the gamma-dose rate were decreased from the last data in the previous annual inspection period mainly due to the short operation time and the longer cooling time. (3)The continuous gamma-ray dose rate distribution up to 10m can be measured by using the PSF in a few minutes. The PSF is suitable to measure the gamma-ray dose rate distribution in the maintenance work area where it is narrow and the mixture of gamma-ray sources from primary pipings and components. The data base of detailed gamma-ray dose rate distribution was greatly extended by the PSF.
Maeda, Shigetaka; Ito, Chikara; Aoyama, Takafumi; Saikawa, Takuya*; Masui, Tomohiko*
no journal, ,
In 2003, Joyo MK-III core was upgraded to increase the irradiation testing capability. This paper describes the details of distributions of neutron flux and reaction rate in the MK-III core that was measured by characterization tests during the first two operating cycles. The calculation accuracy of the core management codes HESTIA, TORT and MCNP, was also evaluated by the measured data. The calculated fission rates of 
U by HESTIA agreed well with the measured one within approximately 4% in the fuel region. MCNP could simulate within 6% in the central non-fuel irradiation test subassembly and the radial reflector region, while large discrepancies were obtained in TORT results. Hence, the precise geometry model was effective in evaluating the neutron spectrum and the flux at such locations.