ML18064A766

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Discusses Mesh,Fortran Program Designed to Generate Fixed Source Input to DOT 3.5.Advises That Given Fuel Assembly Boundaries & Powers & DOT 3.5 Core Model,Mesh Will Assign Power Value to Each Mesh Point
ML18064A766
Person / Time
Site: Palisades Entergy icon.png
Issue date: 08/25/1981
From: Zenter M
BROOKHAVEN NATIONAL LABORATORY
To: Carew J
BROOKHAVEN NATIONAL LABORATORY
References
NUDOCS 9505190194
Download: ML18064A766 (11)
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Text

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SUMMARY

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MEMORANDUM (

DATE: August 25. 1981 TO:

John F. Carew FROM:

M. O. Zenter ~- fi,. 1--1.~.-2.

SUBJECT:

MESH... A Code for Detenni ni ng the DOT Fixed Neutron Source MESH ; s a FORTRAN program* designed to generate f1xed source input to DOT-

3. S. ( l) Given fuel assembly boundaries and powers and the DOT 3.5 cQre model, MESH will assign a power value to each mesh point. Both X-Y and R-C constructions can be used for the reactor model.

I.

INTRODUCTION When the fixed source.input option is chosen in DOT 3.5, a power density value must be provided for each mesh point for each neutron group.

A ty.pical

(~sQ) model of one octant of a reactor has 120 radial nodes, 20 angular nodes, and 16 n*eutron groups, requiring 38,400 input values. Since a power reactor core 1s heterogeneous, the problem~ detennining source terms beccmes

  • one of calculating ~ach mesh block's *loc.ation in the reactor *. This is dor
  • by f1rst overlaying the OOT R.Q or X~V georn~try on the X-Y gecimetry of the core.

Then, as will be expldined below, a sector by sector mapping of the DOT model 1s perf,onned.

If the midpoint of a DOT mesh block is inside a fu~l assembly, it is assigned that assembly's po\\o1er density.

After the mapping is complete,.

the result is multiplied by a 16-group ENDF/13-IV Watt fission spectrum, to pro-vide the required source description.

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II. METHODS

a. Reactor Model MESH is designed to transl ate fue 1 assembly powers to DOT fixed source power data given fuel assembly coordinates.

MESH, using an algorithm des~

cribed below, determines which mesh blocks are in which fuel assembly.

Thus, to model the reactor for input to MESH, 1t f s necessary to provide the coor.d1,,-

l:!

nates of the corners of each fuel assembly, using the reactor center a~ the origin. If it i~ necessary to describe a finer power structure than that given by a whole fuel assembly, then the fuel assemblies can be subdivided and the co9rdinates of the sub-assemblies given_.

S1m1lar1y, if large areas of

. constant power exist~ a coarser model may be used, and the coordinates of the super-assembly input.

b.

DOT Model

  • DOT 3.5 allows spec1f1cat1on of a fixed radial and angular spati.al mesh.

As can be seen from Figure 1, the* core material boundary may vary from sector to sector.

For example. *... Sector 2; mesh 68 is in the. core while in Sector 9t mesh 68 is 1n the reflector. *MESH will list each mesh point and its loca-tion.

Using thf s data w11 l exped1te construe.ting the DOT model and wil 1 also ensure a one-to-one correspondence between DOT and MESH models.

51 nee outside the core region the reactor exhibits* angular symmetry (Fig-ure 1) and has no power source, usually it is only necessary t9 model the core and part of the.reflector for MESH; which will autornatical'lylfzero fill the source terms for the rest of the reactor. :'*.:.... :~: =._*.* *...:.

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c. Ca1culationa1 Procedures It is very important that there be a one-to-one corres*pon.dence between
  • the output produced by MESH and that expected by DOT since DOT has no fixed source input error checking capability. Thus, it is recommended that the fol-lowing procedure be used when preparing. a model.

The reactor core fs usually divided into two zones.

In the first zone the radial mesh is relatively widely sp~ced~.for example. two mesh blocks per fuel assembly.

The radial mesh in the second zone must be much smaller, to account for fuel' assembly.edge effects. A recommended width is half the core shroud (typically ~ 1 cm). The size of the two zones w~ll have to be deter-mined-on a model by model basis, but the second zone should be as small as possible, since there will be a large number of mesh blocks in it. See Fig-ure 1 for an exam~le of how the zones are determined.

The angu1ar or axial mesh must be determined.bY an 1terative process. -

Any required spacing (for e~ample. modeling a surveillance capsule or an in-strument thimble) will have to be set up. Then, a prel1r.iinary angular or.

axial mesh wi 11 be chosen arid a run made.

The adequacy of the mesh can be*

determined by comparing the calculated and input fuel assembly areas.

It is desirable to have the calculated and input c.DJ"e areas as close as possible, and a judicious selection of angular (or axial) and radial mesh spacing w1ll accomplish this. Once an adequate core model has been ach1~ved. 1t can then.

be used as the basis for the DOT 3.5 model.

  • - d~ Calculational Methods

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F1rst, sector boundaries are established, then the mesh calculations be-gin at the core center and step out towards t.he reactor outer boundary.

For

,1 c

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R-Q geometry, the mesh midpoint.is detennined by equations l and 2 and for X-Y geometry, by eQuations 3 and 4, Xm =

R2+Rl (cos (°2;Q1))

2 (1)

R2+Rl c e

+Q ))

Yin =,

SIN.. 2 2 1.

2 (2)

Xm:::

R2+Rl 2

(3)

Ym =

Z2+Z1 2

( 4) where (5) tiRz is the zonewi se radi a_1 1 ncrement ! Ql and g2 are the angular boundarie~ 1n an R-Q modeli and Z2 and Z1 are axial boundaries in an X-Y model.

Mesh areas are determined by equation.6..if an R-Q model is used! and by equation 7 for a~ X-Y geometry, 1T(Q2-Q. 1 \\

2*

2

JJ (R

- R )

, Am ;;;;

360

., 2.

. 1

, (6 ).

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The mesh block is detemined to be inside a fuel assembly if:

FE xmin ~ Xm i FExmax and F Eymi n.5. Ym i F Eymax c

where FExmint FEymin' FExmax' FEymax are the fuel assembly boundar1es.

e.

INPUT The first input field tells MESH whether an X-Y (XY) or R-Q (RT) reactor model is to be used {MESH handles XY and RZ geometries 1~ axJctly the same way).

The second input field is a table of fuel assembly (or super, or sub-assembly) data, consisting of an identificat1on number, left and right x-coordinates, and bottom and top y-coordinates for each assembly.

The assem-blies may be 1n any order in this table, but the fuel assembly po~1ers, speci*

I f1ed 1n the third input f1eld, must be 1n the same order.

Any number (up to a

  • * * -maxir.1um of 220) of assemblies ::~ay be input.

An end of record ca*rd mu~ t bf?

1 ocated at the end of this tab1e so 'MESH can count the number of.fuel assem-blies entered.

The third input field is the list of fuei-assembly powers.

There must be as many of these as there are fuel assemblies, And they must be in the same order as the fuel assembly base table.

The fourth and fifth input fields are-the number of ra'dial and cingular (for an R *.'Q ~odel} or radial and vertical (for an X-Y model) mesh points respectively in the DOT model.

,.5_

. i The sixth input field contains the DOT angular mesh boundaries, (in de-grees) for an R-Q mode1, or the vertical mesh boundaries for an X-Y model.

The seventh through ninth fields contain the number of radial zones in the MESH modelt the radial increment in each, and the boundaries of each zone.

If an X-Y model is to be used, the tenth field 1s the axial power distri-

.bution, consisting of one value for each vert1cal mesh.

The last field is the 16-gro~p ENDF/B-1.V Watt fission spectrum.

Typical MESH sample input for both an XY and R-Q model are g1ven in Ap-pendices A and B~

f. Output The first output field is an 11Echo 11 of all input data.

The second field is a set of data on each fuel assembly, 1n the order it was input. The area of the assembly, based on the input coord1nates, will be listed, as wil 1 the area cal cul atP.d by adding the areas of the mesh bloc.ks de-termined to be inside that fuel assembly.

The input po\\'1er will also be 1 isted. If the calculated area and the input area differ by mor*e than ten percent, an error message 1s printed.

Thi~ implies that the calculational model may be inadequate.

The next output field is a *sector-by~sector 11st1ng of the follow1ng data. First, the sector number and boundary angles or-.vertical mesh are pr1nted. Then,_for each fu~l assembly 1n that sector; the mesh blocks in that fuel assembly are list~d includ1ng their power valu~s. ~idpoints ~nd areas.

Finally, at the end of each sector output, there is a table of mesh*

blocks and their associated fuel assc~bl1es

  • References (1) 11DOT-3.5, Two-Dimensional Discrete Ordinates Rad1at1on Transport.....fode,"

Radiation Shielding Infonnation Center Computer Code Co11ect1on CCC-276

{1976).

cc: M. M. Levine W. Y. Kato L. Lois M. Dunenfel d

o. Fieno

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Appen~;.,,. A Sample input data file fort.. )H R*Q model.

1.

Geometry Indicator

2.

Fuel Assembly Table End of Record*

3.

Assembly Powers

4.

Number of Radial Mesh

5.

Number o~ Angular Mesh

6.

Angular Mesh Boundarie'!:

7.
  • Number of Radial Mesh Zone~
8.

Zone Increments

9.

Zone Boundaries

10.

ENOF/B~IV ~att Fission Spectrum RT

.1 2

3 4

5 6

7 8

9 10 11

' 12 13 14 15 16 17 18 19 20 21 22 4!3 24 25 u-

  • EOR oo.oo 10.39 31.17 51.94 72.72 93.50

. 114.* 27 10.39 31.17

51. 94 72.72
93. 50 114. 27 31.17 51.94 72.72 93.50 114. 27 51.94 72.72 93.SO 114. 27
72. 72
93. 50 114. 27 93.50 lo. 39.

31.17 51.94

72. 72 93.50 114.27 135.05 31.17 51.94
72. 72
93. 50 114.27.

135.05 51.94

72. 72 93.50 114. 27 135.05 72.72 93.50 114. 27 135.05 93.50 114. 27 135.05 114. 27
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. 00. 00 00.00 00.00 oo.oo oo.oo 10.39

10. 39 10.39
10. 39 10.39 10.39 31.17 31.17 31.17 31.17 31.17 51.94 51.94 51.94 51.94
72. 72
72. 72 72.72
93. 50

. 10.39 10.39 10.39 10.39

10. 39 10.39 10.39 31.17 31.17 31.17 31.17 31.17

.31.17 51.94 51.94 51.94 51.94 51.94 72.72 72.72 72.72

72. 72..

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Appendix B Sample input data file for MESH XY model.

l. Geometry Indicator
2.

Fuel Assembly Table End of Record 3 *. Assembly Powers

4.

Number of Radial Meshes.

5.

Number of Axial Meshes 6,

Axial Mesh Boundar1es

7.

Number of Radial Mesh Zones-

8.

Zone Increments

9.

Zone Boundaries

10. Axial Power Shape
11. ENDF/B-IV ~att.Fission Spectrum XY

. l 00.00 IO. 39 2

10.39 31.17 3

31.17 51.94 4

51.94 72.72

5.

72.72 93.50 6

"193.50 114. 27 7

14. 27 135.05 8

135.05.

155.83 9

155.83 176. 60 10 ooo.o 176.6 11 noo.o 176.6 12 ooo.o 176.6 13 ooo.o

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  • EOR 7*1.148.87.586 4*1.0 120 6

61.00 366.0 61.00.

366.0

61. 00 366.0 61.00 i 366.0
61. 00.

366.0 61.00 366.0 61.00 366.0 61.00.

366.0 61.00 366.0 ooo.o 30~5 30.5 61.0 366.0 396.5 396.5 427.0 o.o 30.5 61.o 88.73 116.45 144.lB 171.91 199.64-

  • 227.35 255,89 ia2.a2 Jlo.ss 338.27 366.o 396.s 427.o 2

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