ML16257A078
| ML16257A078 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 08/25/2016 |
| From: | Entergy Operations |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML16256A115 | List:
|
| References | |
| W3F1-2016-0053 | |
| Download: ML16257A078 (4) | |
Text
WSES-FSAR-UNIT-3 11.1A-i APPENDIX 11.1A DERIVATION OF RESIDENCE TIMES
WSES-FSAR-UNIT-3 11.1A-ii APPENDIX 11.1A TABLE OF CONTENTS SECTION TITLE PAGE 11.1A DERIVATION OF RESIDENCE TIMES 11.1A-1 11.1A.1 CIRCULATING CRUD 11.1A-1 11.1A.2 DEPOSITED CRUD 11.1A-3
WSES-FSAR-UNIT-3 11.1A-1 APPENDIX 11.1A DERIVATION OF RESIDENCE TIMES The derivation of the core residence times for circulating crud and deposited crud as shown in Subsection 11.1.2 is as follows:
11.1A.1 CIRCULATING CRUD:
The number of radioactive atoms (Nf) in the crud film on in-core surfaces at any time is:
1)
(A N
dt dN f
i i
f
=
Solving for Nf yields the following:
(
)
2)
(A atom/g e
1
=
N res it i
i f
where:
i
=
the activation rate for each isotope i (d/g-sec) i
=
the decay constant for each isotope (sec -1) and tres
=
the desired core residence time (sec).
The number of radioactive atoms (Nc) released to the reactor coolant at any time is:
[
]
(
) N
+
+
A ER N
=
dt dN c
i c
f c
atoms/sec Solving for Nc yields the following:
[
]
(
)
(
)
(
)
t
+
+
i c
f c
i e
1
+
+
A ER N
=
N
(A-3) where:
ER
=
the erosion rate (g/cm2)
Ac
=
the core surface area (cm2)
=
the plateout rate (sec-1)
=
the purification cleanup rate (sec-1) i
=
the decay constant (sec-1)
WSES-FSAR-UNIT-3 11.1A-2 Revision 11 (05/01)
The total amount of crud (Mc) released to the reactor coolant any time is:
[
]
(
)
c T
c M
+
A ER
=
dt dM
(A-4) where:
Mc includes both radioactive and nonradioactive material
Solving for Mc yields:
[
]
(
)
(
)
(
)grams e
1
+
A ER
=
M t
+
T c
(A-5) where:
ER
=
the erosion rate (g/cm2)
AT
=
the total system area (cm2)
=
the plateout rate (sec-1)
=
the purification cleanup rate (sec-1)
The activity (Ai) of the crud released to the reactor coolant is:
coolant reactor in crud of gram per dps M
N A
c C
i i
=
(A-6)
Substituting the values of Nc and Mc into the above expression and assuming i is small when compared to and, the activity of the crud is as follows:
(
)
(
)
0.06 A
A e
1
=
A T
c t
i i
res i
dpm/mg-crud (A-7) where:
0.06
=
a constant changing dps/g-crud to dpm/mg-crud This activity (Ai) is also assumed to be the activity of the crud which plates out on out-of-core surfaces.
Solving equation (A-7) for tres yields equation (3).
11.1A.2 DEPOSITED CRUD The activity (Aj) of the deposited crud is:
(
)(
)
0.06 e
1 N
A res it i
f i
j
=
=
(A-8)
Solving equation (A-8) for tres yields equation (4).