ML20247H360

App 11A, Core Residence Times, to CESSAR Sys 80+ Std Design

ML20247H360
Person / Time
Site:	05200002, 05000470
Issue date:	03/30/1989
From:	ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY
To:
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ML20247G537	List: LD-89-035, Forwards Vols 1-17,consisting of Chapters 1-18,to CESSAR Design Certification, for Approval,Per 10CFR52 ML20247G666 ML20247G678 ML20247G714 ML20247G851 ML20247G862 ML20247G868 ML20247G913 ML20247G928 ML20247G983 ML20247G989 ML20247H033 ML20247H291 ML20247H308 ML20247H316 ML20247H336 ML20247H353 ML20247H360 ML20247H394 ML20247H397 ML20247H403 ML20247H417 ML20247H427 ML20247H443 ML20247H453 ML20247H470 ML20247H478 ML20247J059 ML20248B002 ML20248C380 ML20248C392
References
NUDOCS 8904040445
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Text

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APPENDIX 11A CORE RESIDENCE TIMES I

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CESSAR 8!nincano,. (Sheet 1 of 1) o EFFECTIVE PAGE LISTING APPENDIX 11A Table of Contents P_ age Amendment i

Text Pace Amendment 11A-1 11A-2 11A-3 O

O Amendment E December 30, 1988

CESSAR !!nifico =

TABLE OF CONTENTS

-APPENDIX 11A Section Subiect Pace No.

1.0 DERIVATION OF CORE RESIDENCE 11A-1 l TIMES j i

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CESSAR !! Sinc m.,

O 1.0 DERIVATION OF CORE RESIDENCE TIMES The derivation of the core residence times for circulating crud as shown in Section 11.1.2 is as follows:

A. Circulating Crud:

The number of radioactive atoms (Nf ) in the crud film on in-core surfaces at any time is:

dN g dt *Ed- i 1"f (11A-1)

Solving for N g yields the following:

Ng =

(1 - e ^I #*8) atoms /g (11A-2) i Where: I f

4 is the activation rate for each isotope i (d/g-sec),

A is th decay constant for each isotope f (secs p), and t

res is the desired core residence time (seconds).

The number of radioactive atoms (N c ) released to the reactor coolant at any time is:

[DN=N f [ER] A c ~

("+0+A i) N c atoms /sec Solving for N c yields the following:

Nf (ER) A c "I" + 0 + A 1) t N

o" (a + B + A.) 1 (1 - e ) (11A-3) 2 Where: ER is the erosion rate (g/cm -sec),

A c is the core surface area (cm ),

o is the plateout rate (secs-1),

a llA-1

1 CESSAR E!i#icari:u I

(secs-1),

Oi p is the purification cleanup rate and A

y is the decay constant (secs-1),

Total amount of crud (M ) released to the reactor coolant  ;

any time is:

dM dt

=

[ER) A T -( + )M c (11A~4) where M c in ludes both radioactive and nonradioactive material.

Solving for M c yields:

l l M (1 ~ *

- (a + )t) grams (11A-5) c" )

Where: ER is the erosion rate (g/cm -sec),

1 A is the total system area (cm ),

T

~

a is the plateout rate (secs ~ ), and p is the purification cleanup rate (secs ~1).

The activity (Ag) of the crud released to the reactor coolant is:

AN fC A

1=M c , dps per gram of crud in reactor (11A-6) coolant substituting the values of N and M into the above expression and assuming 1.l is shall when compared to a and p, the activity of the crud is as follows:

A c

Ag=If (1 -e ~ i res) (0.06) dpm/mb-crud lu-7) where 0.06 is a constant changing dps/g-crud to dpm/mg-crud.

This activity (A. is also assumed to be the activity of the crud which plated) out on out-of-core surfaces.

Solving equation (11A-7) for t es yields quation (1) (See Section 11.1.2).

11A-2

CESSAR ninneuio B. Denosited Crud The activity (A ) of the deposited crud is 3

A =A gN g = Zy d (1:- e res).0.06 (11A-8)

Solving equation (11A-8) for't res yields. equation (2) . (See Section 11.1.2) 1 i

11A-3