ML20151P373

Comments on Numec Opposition to AEC 661207 & 16 Review & Comments Re Safety Analysis for PWR Area.Numec Should Correctly Consider H/X-density Correspondence

ML20151P373
Person / Time
Site:	05000135, 07000135
Issue date:	01/23/1967
From:	Luke C US ATOMIC ENERGY COMMISSION (AEC)
To:	Nussbaumer D US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8601080763
Download: ML20151P373 (3)

Text

.- _ __ - _______ .___ ___________

.g. n ,.- . . .

f, /t Sc l

['

UNITED STATES GOVERNMENT Memorandum l To  : Donald A. Nussbaumor, Chief, Source and DATE: January 23, 1967 Special Nuclear llatorials Branch, D?!L COM  : Charles D. Luke, Chief Criticality Branch, Df!L '

stcjact: NUCLEAR flATERIALS AND EQUIPl!ENT CORPORATION (NIf!EC),

PWR LETTER, JANUARY 6, 1967, DOCKET No.70-135

~

i i

REFERENCE:

(1) Ltr, DAN to l'lf!EC, 12/16/66 (2) lleno, CDL to DAN,12/7/66 l (3) NIA!EC Application, 1/4/67 [

L Dt!L:CB:GIB Nlt!EC disagrees with our review and connonts (Ref. I and 2) concerning the safoty analysis for the PWit area. No offer the following comments: {

a

(

1. In response to our first comment, tRf tEC states that the fraction critical " extrapolation to 0.6 as proposed in our application...  ;

is indeed reasonabic and conservativo. Such analysis will bo pro-  ;

sented at a later dato to justify use of largor individual units...." i NtftEC contradicts this in the second paragraph by stating: "Uo l agroo with you that an individual unit having a fraction critical  ;

value of 0.6 when baro could be critical if fully reficcted."

NittEC indicates full reflection is credible. We cannot agroo,  !

thereforo, that the critorion '

of 0.6 is indood reasonablo and  ;

conservativo. i NiflEC states the intent is to use only the units in Table XII-1 and that each unit will meet the critoria of TID-7016, Rev.1. l Wo havo no objection to the critoria in TID-7016, Rev. 1. Wo do j not agroo that the Tablo XII-1 units moet the critoria because L Ntf!EC has not dononstrated il/X donsity correspondence. l

2. Concerning our second comment, Ntt!EC statos: "This statement by j you shows lack of undorstanding of the PWR process which is described -

on page XII-1 of the application wheroin it is stated that the ll/X '

U-235 density rotationship applies to ' Fully enriched coramic grado 002 powdor...blonded with customer speciflod ceramic grado powders,  ;

and prossed...into thin warors.' 11ocause of the stated prosence of  !

diluonts in the prossed wafors, the nornal void volumo associnted i with lower density U-235 cannot bo tal.on up by water and hence tho  :

density ll/X reintionship specified in the abscissa of Figuro 1 of i TID 7016, Rev. 1, for salts and slurrios, does apply."

29M 81%>

hy U.S. Satings %Is Regularly on liv Pa) roll Satings Plan ,

I

o o Donald A. Nussbaumor January 23, 1967 ,

The diluent is not present in all operations for Pl!R wafer production, e.g., the U0 3 as received and initially handled is not diluted. Even where diluent is present, the minimum diluent volumo fraction is not stated.

An examplo may best illustrate our disagreement concerning the ,

il/X-density correspondence.

3

1. NtR1EC stated density: fl2.87gU/cm.

2. For UO,-H 2 O at the stated density, il/U = 6.2 (

Reference:

L. C. Amos,lill-64421).

l

3. Ilocause the uranium is fully enriched, II/U = II/U-235.

4. From Figuro 1, TID-7016, Rev. 1, for an ll/U-235 ratio of 6.2, the corresponding U-235 density (Po) is about 1.7 g U-235/cm3

5. The mass 11 nits of TID-7016, Rev.1, should be reduced by the factor (fo/P)N, whero N = 1.5 (

Reference:

Fig. 7, TID-7028.)

3. Ntt!EC contends that the homogenization process is conservativo in datormining the fraction critical of the storage array. NtR!EC con-l tends that array reactivity increases with additional units, but that fraction critical does not necessarily increase. ife agree with NittEC that reactivity of the array increases with the addition of units. Wo disagroo with NtR!EC concerning the fraction critical statement. Considor, for examplo, a bare critical array of N units.

Each unit has a fraction critical value of 1/N. As each unit is added to the array, the fraction critical increases linearly by 1/N.

The reactivity also increases, but not necessarily in a linear nanner.

i Nlf tEC has erred in changing the basis for the fraction critical calculation. For the single unit, the cell voluno is considered to be the unit volumo. As cach unit is added to tho array, the space betwcon units is added to the coll volumo. NttlEC then homo-genized the several units and spaces in arriving at a fractional critical loss than that of a single unit. ,

The NIEtEC method does not ensuro safety. For examplo, two critical units could be so spaced that a shapo factor greater than 2 is cat-culated. !!athematically dividing the two critical masses by tho l

l i

O O l

Donald A. Nussbaumer January 23, 1967 shape factor results in a subcritical array. However, floa a physical standpoint, the two critical units represent a super-critical array. We realize NtfHIC does not have critical units.

We are demonstrating only that the homogenizing process is not conservative.

In su.amacy, IMHIC should:

1. Correctly consider the ll/X-density correspondence. NtIU!C has stated that only the safe units froa TID-7016, llev.1, will be used. The errors identified in our Connents 1 and 2 would be non-existent if NtI!!!C would correctly apply the ll/X-density criterion. In the latest subnission, !MtEC has stated that the 0.6 fraction critical criterion will not be used.

2. Correctly calculate the fraction critical for the internediate storage array.

NtInic has submitted (Ref. 3) a revised panc XII-19 to cliainate a clerical error. This revision does not affect our comments in Ref. 2 or in this menorandum.

.