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JAEA-Data/Code 2007-004 - Welcome to Research Group for ...

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DENFP A<strong>to</strong>mic number density (*10 24 n/cm 3 ) at every burn-up step (0,1, 2,…,IBC1)<br />

Repeat Block-11-2 until MPOS=0 is encountered.<br />

Then repeat Block-11-1 through Block-11-2 IBC9 times.<br />

<br />

XE5<br />

/ NAMFP (Block-11-1)<br />

1 / MPOS(Block-11-2-1) <strong>for</strong> 1st Fuel<br />

11(0.0) / DENFP (Block-11-2-2)<br />

5 / MPOS <strong>for</strong> 2nd Fuel<br />

11(0.0) / DENFP<br />

0 / MPOS=0 : End <strong>for</strong> Xe-135<br />

SM9<br />

/ NAMFP (Block-11-1)<br />

1 / MPOS(Block-11-2-1) <strong>for</strong> 1st Fuel<br />

11(1.23E-4 ) / DENFP (Block-11-2-2)<br />

5 / MPOS <strong>for</strong> 2nd Fuel<br />

11(1.23E-4) / DENFP : Peak Sm-149<br />

0 / MPOS=0 : End <strong>for</strong> Sm-149<br />

--------------------------------------------------------------------------------------------------------------------------<br />

calculation.<br />

The following notices and recommendations would be helpful <strong>for</strong> the use of burn-up<br />

• Burn-up step interval<br />

At every burn-up step, effective microscopic cross-sections and flux distribution are updated<br />

and output edit is prepared. As change of composition is calculated by an analytical method at every<br />

sub-step (10 sub-steps in the initial step <strong>to</strong> accurately consider Xenon buildup and 3 sub-steps after<br />

that are internally set), the interval has not necessarily <strong>to</strong> be short. Normally, 5,000 ∼ 10,000 MWd/t is<br />

used. However, the initial Xenon buildup and the treatment of burnable poison of relatively short<br />

lifetime should be taken care of.<br />

• Multiplication fac<strong>to</strong>r and cross-sections at the final step<br />

At the end of final burn-up step, the composition of depleting material is edited, but the<br />

spectrum calculation <strong>for</strong> this composition is not executed. There<strong>for</strong>e, values are not printed out <strong>for</strong><br />

multiplication fac<strong>to</strong>r and conversion ratio corresponding <strong>to</strong> the final composition. Neither<br />

cross-sections nor flux are written in<strong>to</strong> PDS files.<br />

The user should keep in mind that the step be<strong>for</strong>e the last gives the upper limit of burn-up in the<br />

tabulation of cross-sections <strong>for</strong> the succeeding use of COREBN.<br />

• Chemical binding effect of fuel material<br />

Mixed use of U08W (chemical binding of UO 2 is reflected) and U080 (free gas model) should<br />

144

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