NEA-1662 IRPHE/JOYO MK-II.

1. NAME:  IRPHE/JOYO MK-II.

3. DESCRIPTION

The JOYO MK-II core consists of fuel subassemblies, reflectors, control rods and other core components. Its height, equivalent diameter and volume are 55 cm, approximately 73 cm and approximately 235 liters, respectively. The maximum thermal power is 100 MWt.
  
A core characteristics database was developed for the MK-II core of the experimental fast reactor JOYO and published in 1998. It contains the calculated results with the core management code system MAGI i.e., the core characteristics parameters and irradiation conditions, and the core characteristics data measured in the duty operational cycles and special tests. Since then, it has been used for the studies on core design and analyses of post-irradiation tests.

The database contains all the core management data and core characteristics data measured in the operating characteristics tests conducted during the startup and shutdown of each operating cycle. These data include excess reactivity, control rod worth and fitting coefficients for control rod calibration curve, isothermal reactivity coefficient, power reactivity coefficient and burn-up reactivity coefficient, along with their measurement conditions.
  
The "Core Configuration Data" contain the refueling history and the core configuration in each cycle for the MK-II core. The "Subassembly Library Data" contain the fuel composition data at the fabrication for a total of 362 driver fuel subassemblies and 69 irradiation test subassemblies that have been irradiated so far. It also contains the burn-up composition, neutron fluence, burn-up, burn-up ratio, cumulative power, et al., calculated with the core management code system MAGI for each cycle. The "Irradiation Data" include the neutron flux, gamma-ray flux, power density, power, linear heat rate, coolant temperatures, fuel maximum temperature and et al., calculated with MAGI for each subassembly at the beginning and end of each cycle. These data are stored in one file for each cycle. The reactor kinetic parameters are also stored.
  
Many requests have been received from the users to upgrade the database by, for example, implementing a new nuclear data library and supplementing additional data. Responding to these requests, the JOYO MK-II core characteristics database has been revised.

The major revisions are: As a response to the requests from the users and an expansion of the operating characteristics data,
1) The group constant set JFS-3-J2 based on JENDL-2, used in the neutronic calculations in MAGI, was replaced by JFS-3-J3.2 based on JENDL-3.2,
2) Data for control rod total worth and reactor kinetic parameters,
3) The results from the MK-II performance tests were added, and
4) The core characteristics from the 32nd to 35th cycles, which were conducted after the first version, were added.

7. UNUSUAL FEATURES

The data can easily be modified by the editor software on PC with Windows95 or higher. Since Macintosh cannot identify the carriage return code of MS-DOS, the text files should be converted to the Macintosh text files by using the Internet browser (Netscape Navigator 3.0 or higher, or Internet Explorer 3.02 or higher).

The users can perform core characteristics analyses on EWSs (engineering workstations) or mainframe computers by retrieving the core management data from the CD-ROM, and improve not only the analysis methods but also the core design through the comparison between the calculated results and data taken in an actual reactor JOYO.

- Y. Ohkawachi, S. Maeda, H. Nagasaki, T. Sekine and T. Aoyama:
JOYO MK-II Core Characteristics Database (Research Document)
JNC TW9409 2003-001 (April 2003)

15. NAME AND ESTABLISHMENT OF AUTHORS

Japan Nuclear Cycle Development Institute
O-arai Engineering Center
4002, Narita-cho, O-arai-machi
311-1393 IBARAKI-KEN
Japan

ReadMe.txt: Usage of CD-ROM for core characteristics database
report.pdf:  Research document JNC TW9409 2003-001
figA-1.pdf: Structure of JOYO MK-II core characteristics database (Fig. A-1)
figA-2.pdf: File structure on CD-ROM for core characteristics database (Fig.
A-2)
\CONFIG "Core configuration data":
  address.pdf: Relationship between JOYO location nb and core address (Fig. 4-1)

  fu_exc.pdf: MK-II core refueling history
  config.xls: Core configurations for 0th to 35th cycles
  00cyc.pdf: Core map for 0th cycle (performance test)
  XXcyc.pdf: Core map for 1st cycle to 35th cycle
\CORE-CAR "Core characteristics data" (Excel and PDF files):
  k-eff.*: Excess reactivity and burn-up reactivity coefficient
  t-worth.*: Control rod total worth (Inverse kinetic method and period method)
  cr-worth.*: Control rod worth (Fitting coefficients for calibration curve
  temp.*: Isothermal reactivity coefficient
  3cyc-temp.*: Isothermal reactivity coefficient in 3rd cycle
  power.*: Power reactivity coefficient
\DYN-CHA "Reactor kinetic parameters": Effective delayed neutron fractions,
decay constants of precursors and prompt neutron lifetime (Excel and PDF files)
  beta-eff.*: Effective delayed neutron fractions
  ramda.*: Decay constants of precursors
  lp.*: Prompt neutron lifetime in each cycle
\OUTPUT "Irradiation data": Neutron flux, gamma-ray flux, heat generation
density, power, linear heat rate, coolant flow, and temperature distribution
  00cyc.txt: BOC and EOC of 0th cycle (performance test)
  XXcyc.txt: BOC and EOC of 1st cycle to 35th cycle
\RAND "Subassembly library data": Composition, burn-up, burn-up ratio,
neutron fluence and cumulative power
  -\BOC (beginning of core):
  00cyc.txt: 0th cycle (performance test)
  XXcyc.txt: 1st cycle to 35th cycle
  -\EOC (end of core):
  00cyc.txt: 0th cycle (performance test)
  XXcyc.txt: 1st cycle to 35th cycle