TSUNAMI-3D and Dancoff factor

[Jimbo]

Hi, 

I am trying to calculate the Dancoff factors for the 3 rings (4+8+16=28 elements) of fuel pins in a CANDU-type bundle, for a TSUNAMI-3D calculation.  I followed the instruction in item #8 (pg. M24.3.2) of the MCDancoff manual (M24mcdancoff.pdf), which states: 

 

8. If executing TSUNAMI-3D, additional steps are necessary because TSUNAMI-3D does not treat the dan2pitch input parameter. Return to the original TSUNAMI-3D input file and replace the sequence name to “CSAS-MG PARM=CHECK” and delete all data after the unit cell data to quickly obtain revised pitch values. (Note: CSAS will not modify cell dimensions to more than 20 cm, so a revised moderator density may need to be entered to obtain the desired Dancoff factor.) Search for the word “desired” in output file to find new pitch values for each cell.

However, after I followed the above and deleted all the (most geometry) data after the unit cell data (which I interpret as the following data block) and ran CSAF-MG,

read celldata

  latticecell triangpitch fuelr=0.7105 3 gapr=0.7155 6  cladr=0.7609 7  hpitch=0.82237 11 end

  latticecell triangpitch fuelr=0.7105 4 gapr=0.7155 61 cladr=0.7609 71 hpitch=1.01487 12 end

  latticecell triangpitch fuelr=0.7105 5 gapr=0.7155 62 cladr=0.7609 72 hpitch=0.82055 121 end

end celldata

I could not locate the desired Dancoff factors in the output file, which I expect to be similar to the following according to the MCDancoff manual: 

unit cell = 1

  original pitch = 1.7340E+00

  Dancoff for orig pitch = 2.9728E-01

  desired Dancoff = 3.3600E-01

pitch to produce desired Dancoff= 1.6845E+00

I do see the following data relevant to the Dancoff factor: 

                                       dancoff calculations for cell     1

  zone mixn dancoff(out)    area(out)  dancoff(in)     area(in) dancoff(initial)                 dancoff's by row

                                                                                geometry     row1        row2        row3

     4   11  1.00000E+00  8.63550E-01  5.02275E-01  7.60900E-01  0.00000E+00

     3    7  8.63222E-01  7.60900E-01  5.03501E-01  7.15500E-01  0.00000E+00    cylinder 1.40210E-01 3.66068E-03

     2    6  8.18025E-01  7.15500E-01  5.01230E-01  7.10500E-01  0.00000E+00    cylinder 1.27518E-01 8.81978E-03

     1    3  8.15746E-01  7.10500E-01  1.00000E+00  0.00000E+00  0.00000E+00    cylinder 1.26796E-01 9.16117E-03

How can I get the "pitch to produce desired Dancoff" mentioned in the manual?

Any help will be much appreciated. 

Regards

JC

[Jeremy]

I would expect MCDANCOFF to output the dancoff factors to a series of files with endings like .danc000000000027

[Jimbo]

Jeremy,

My understanding is that the output file you mentioned is useful only as input for dan2pitch.  Unfortunately, I need the parameters for a TSUNAMI case as described in my original posting.

Thx for caring though,

J. 

[Winfried Zwermann]

In your CSAS-MG celldata block, you should add the corresponding centrm data entries for evaluating effective pitches from the Dancoff factors calculated by MCDANCOFF. It looks like this (where ... are the Dancoff factors):

read celldata

  latticecell triangpitch fuelr=0.7105 3 gapr=0.7155 6  cladr=0.7609 7  hpitch=0.82237 11 end

    centrm data dan2pitch(3)=... end centrm data

  latticecell triangpitch fuelr=0.7105 4 gapr=0.7155 61 cladr=0.7609 71 hpitch=1.01487 12 end

    centrm data dan2pitch(4)=... end centrm data

  latticecell triangpitch fuelr=0.7105 5 gapr=0.7155 62 cladr=0.7609 72 hpitch=0.82055 121 end

    centrm data dan2pitch(5)=... end centrm data

end celldata

Best regards,

Winfried

[Jimbo]

Winfried,

Thanks.  It worked after I added the centrm data.  

I wouldn't have to go through this if TSUNAMI could treat dan2pitch.  A more explicit description of the manual might also have helped.  

Thanks again.

Best Regards,

Jimmy