ML20204A280
| ML20204A280 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 08/18/1982 |
| From: | Cepress R, Hickman R, Townsend D BWR OWNERS GROUP |
| To: | |
| Shared Package | |
| ML20204A279 | List: |
| References | |
| DRF-E31-00022, DRF-E31-22, NSEO-78-0882, NSEO-78-882, TAC-56049, TAC-59542, NUDOCS 8605120018 | |
| Download: ML20204A280 (19) | |
Text
-
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INSTRUCTIONS FOR CALCULATION OF 0FFSITE DOSE FROM LIMITING PRIMARY SYSTEM BREAK WHICH DOES NOT ISOLATE PRIMARY CONTAINMENT VENT AND i
PURGE VALVES D
O 8605120018 860428 PDR ADOCK 05000321 P
PDR O
1 NSEO 78-0882 DRF E31-00022 INSTRUCTIONS FOR CALCULATION OF OFFSITE DOSE FROM LIMITING PRIMARY SYSTEM BREAK WHICH DOES NOT ISOLATE PRIMARY CONTAINMENT VENT AND PURGE VALVES Prepared by:
a.
4.
7
- ,/v; SM R. G. Cepress, Engineer',
Systems Design and Analysis Reviewed by:
,7 h.~
w tm.N.
5 ' ' C-D. B. Townsend, Senior Engineer System Design and Analysis Reviewed by:
~((
e-R. D. Hiclunan, Principal Licensing Engineer BWR Systems Licensing M.f2, Reviewed by:
L*
zcp 7
H. Choe, MaMger" Systems Design and Analysis Approved by:
~
A.' H. Oates, Manager Plant Systems and Structural Analysis N
J. F. Schilder Senior Program Manager BWR Generic Programs Nuclear Services Department
INSTRUCTIONS FOR CALCULATIONS OF OFFSITE DOSE FROM LIMITING PRIMARY SYSTEM BREAK WHICH DOES NOT ISOLATE PRIMARY CONTAINMENT VENT AND PURGE VALVES Table of Contents Section P.,a2'
- 1. 0 Introduction 1
2.0 List of Parameters 2
- 3. 0 Assumptions 4
4.0 Calculation of Leakage Flow 1.
Analytical Method 5
2.
Sample Calculation for a 5
Typical Plant 5.0 Calculation of Offsite Dose 1.
Analytical Methed 7
2.
Sample Calculation for a 8
Typical Plant 6.0 References 10 APPENDICES A
Summary of General Equations B
Nominal Values of Input Parameters C
Fluid Properties L
i
O 8
s
1.0 INTRODUCTION
The BWR Owners Group supplemental position on NUREG-0737, Item II.E.4.2, Part 7 was provided in Reference 1.
That position states that no automatic isolation of the containment vent and purge valves on high radiation is required if it can be shown that the offsite dose from the largest break which will not automatically isolate the vent and purge valves is acceptable. The acceptance criterion suggested by the NRC staff is the EPA's Protective Action Guide, i.e., 5 Rem thyroid dose.
Reference 1 further states that utilities will be prot'ided with a list of the assumptions used and the procedure for performing this analysis.
This report provides the assumptions and the procedure for performing the plant unique analysis to justify that no automatic isolation of the purge and vent valves on high radiation is required. Those parameters used in the calculation which are plant unique have been identified.
Although the methods and assumptions described in this report are deemed appropriate for satisfying NUREG-0737. Item II.E.4.2, Part 7 individual utilities may be able to justify alternative analytical approaches with the NRC. This report is not intended to preclude the use of such alternate approaches.
i I
I e
4 - --
3 - -. -
2.0 LIST OF PARAMETERS The following is a list of the parameters used in these analyses.
Values of parameters that are plant unique are identified by ".
Where the value of a parameter is not plant unique, the value to be used in the calculation is specified in the text of the procedures which follow and also in Appendix 8.
specific activity of primary coolant water, pCi/gm,1-151 a
=
specific activity of inflow water, pCi/gm a
=
g a,
initial specific activity of coolant, pCi/gm
=
a, activity source rate, pCi/hr
=
technical cp'ecification coolant specific activity, pCi/gm a
ts k
activity release rate, Ci/hr
=
A
=
spiking activity release per bundle, C1/ bundle B
A
=
1 dine inventory due to depressurization spiking, C1 D
A, total iodine inventory in the reactor, Ci
=
k, activity release rate with spiking, Ci/hr
=
breathing rate, m2/sec B
=
D offsite thyroid dose, rem
=
d
=
vent pipe diameter, in, friction factor f
=
partitioning factor (iodine in steam / iodine in water) f
=
p specific enthalpy of ifquid, Stu/lbm h
=
g specific enthalpy of vaporization, Btu /lbm h
=
fg I
=
thyroid dose conversion factor for I-131, rem /Ci c
K
=
total resistance coefficient 3
K
=
resistance coefficient for a given valve B
K
=
resistance coefficient for elbows (per elbow)
C K
=
resistance coefficient for sudden contraction sc K,,
resistance coefficient for sudden expansion
=
vent pipe' length, ft L
=
L/d vent pipe effective length to diameter ratio
=
2
~
'n,
O mass flow rate, 1bm/hr a
=
M, total mass of reactor coolant, Ibn
=
N
=
number of fuel bundles B
pressure, psia
- p
=
volumetric flow rate, cfm q
=
Re
=
Reynolds number of flow Q
break flow rate, gpm
=
b 5,
rate of activity release to reactor water, pCi/gm-hr
=
time, hours t
=
specific volume of steam, ft2/lbe v
=
9 i specific volume of liquid, f t3/lbm v
=
f fraction of coolant that flashes to steam x
=
x/q atmospheric dispersion factor, sec/m3
=
Z
=
elevation of vent piping, ft
~
activity removal rate time constant, hour 1 a
=
filter efficiency c
=
f decay constant, hours ~2 A
=
viscosity, centipoise p
=
I e
3-
=.
t 3.0 ASSUMPTIONS The assumptions used in this analysis are as follows:
1.
Drywell pressure equal to containment isolation setpoint (2.0 psig).
2.
Drywell atmosphere is saturated steam.
3.
No plateout or fallout of iodine in containment or vent piping.
4.
No steam condensation in drywell or in purge or vent pipes.
5.
Fluid flow through a break is saturated water at 1000 psia (constant throughout the event).
6.
All, iodine in flashed coolant assumed released.
7.
No credit for standby gas treatment system (SGTS) or reactor water cleanup system (RWCS) filtration.
8.
Initial primary coolant iodine concentration at the technical specification limit.
9.
Iodine spiking included (95% cumulative probability value) for depressurization event.
',10.
Operator action time to close purge and vent valves = 10 minutes.
g 11.
Annual average meteorology.
12.
Regulatory Guide 1.3 breathing rates, i
~
i l
l i
1...
'b 4.0 CALCULATION OF LEAKAGE FLOW 1.
Analytical Method The leakage flow equation given in Appendix A (equation A.1) can be simplified for all plants through the use of assumption (1),
stated in 3.0.
This assumption gives P
-P of 2 psi, the entranceconditionat16.7 psia,theex}tco$ditionat14.7 psia and the average at 15.7 psia.
Substitution of the fluid properties as specified by this assumption into Appendix A equation (A.1), yields the steam flow rate for the nth pipe:
7341 - (23 - 2 )n q" = 2.625 d2 3
"^f K *U*AU I
~I n1 where the subscripts 1 and 2 refer to conditions at the vent pipe inlet and outlet, respectively.
The resistance coefficient K is calculated 'as follows:
~
K,n = K
+(g)(n.
f valves f the same type) +
sc se "C (n.
elbows of the same type) + f(L/d)
(4-2)
The break flow is calculated as follows using equation (A.2):
1 N
- 58.19 b 9 b
n (4-3)
The flashing factor for fluid exiting the break is calculated from equation (A.3) as follows:
x =.3687 (4-4)
The activity release rate for the nth pipe is calculated from equation (A.4) as follows:
ag A,='936 5 C1/hr (4-5) using assumptions (6) and (7) of Section 3.0, i.e., f = 1.0 P
and cf=0 The Reynolds number of flow is:
Re ='1142 q /d (4-6) n n w.-
~...
2.
Sample Calculation for a Typical Plant Nominal values of plant parameters and typical plant configuration details are:
1)
Flow out of vent line only.
2)
Diameter of vent line = 24 in., (d = 24 in.).
y 3)
Three butterfly valves.
4)
Five 90* elbows.
5)
Vent pipe length = 400 ft.
6)
No elevation change (23-2 = 0).
Using the typical resistance coefficients as specified in (A.11):
K =.5 + 1.0 + (3)(20f) + (5)(20f) + f (400 12) g4,7)
K = 1.5 + 360f (4-8)
Since the vent flow is expected to be turbulent, the friction factor, as specified by Reference 2, is:
f =.0122 (4-9) and the total resistance coefficient becomes K = 5.892 (4-10)
Substitution of the nominal values of plant parameters and (4-10) into (4-1) yields a volumetric steam flow rate of q = 52,910 cfm (4-11)
This flow rate yields a Reynolds number of Re = 2.52 x 108 (4-12) which checks with the friction factor used.
The break flow is calculated using (4-3) 4 Q = 912 gpm (4-13) b and the activity release rate is calculated using (4-5):
4 = 11.30 C1/hr (4-14) assuming a = a
= 0.2 pCi/gm ts..
l.
5.0 CALCULATION OF OFFSITE DOSE 1.
Analytical Method Following vessel depressurization (due to normal shutdown and cooldown, or a break) iodine spiking activity is released from the fuel which significantly increases primary coolant specific iodine activity relative to normal operating conditions at constant power.
At time zero (completion of vessel depressurization), all of the iodine spiking activity is assumed to be released to the coolant.
The total activity in the coolant is obtained by using (A.19), (A.20) and (A.21). The total coolant activity is:
~
., A, = 4.5359 x 10
- M,ats * "B B (5-1)
A The initial activity release rate with spiking can be obtained by scaling up the release rate due to the technical specification iodine concentration alone.
The result for the release through the nth pipe is:
N ^8 + 4.
59 x 107 8
M, a,
g sn n
4.5359 x 10 4 M, ats
(~)
which corresponds to an initial specific coolant activity of 7
NAB 8 + 4. 359 x 10 M, ats a
=a 5
4.5359 x 10 4 M, a,
(5-3) g The time dependent coolant activity with no source is determined from (A.14) to be
~
s(t) = a,e (5-4)
Assuming the break flew is the only significant removal mechanism, then we obtain the following from equation (A.15)
I
\\
60 break "
b v
7.48 (5-5)
M, f
assuming again that f
= 1.0 The average to initial coolant specific activity is obtained from (A.18)
~
[~ (t
~
1
-sty
,-=t )
a g
f
-t)
(5-6)
=
e, f
j, where t and t are the final and initial times, respectively.
f g
~7-p__-
..-wn.1 sa
The incremental site boundary thyroid dose due to release j
through the nth pipe can be calculated by combining (A.13) and (A.18) as follows by correcting for activity change in the primary coolant:
Dn"Ic s6 I X# jn j
- j (5-7) 3 j
o D, =
I X
E'
~'
(5-8) jn j j
The total thyroid dose due to release from all possible vent paths is:
,D = I D, i
n 2.
Sample Calculation for a Typical Plant Nominal values of typical plant parameters are:
~
8 2.32 x 10 4 B
=
m /sec 6.5 x 105 lbm M*
=
0.2 pCi/gm a
=
ts N
=
764 0
3.27 C1/ bundle A
=
0 1.49 x 108 rem /Ci 1
=
ykq
~
6.3 x 10 7 sec/ms
=
From calculations shown in Section 4.1:
d 11.30 Ci/hr
=
Q 912 gpm
=
b The total coolant activity from (5-1) is A, = 4.5359 x 10 4 N,ats + N ABB (5-9)
~
A, = (4.5359x10 4)(6.5x10s)(.2) + (764)(3.27) C1 (5-10)
A,= 60 + 2500 C1 (5-11)
A,= 2560 C1 (5-12)
- m..
- _. ~ _
\\
The activity release rate with spiking (A,) is I, = ; 256 Ci/hr (5-13) 0 A, = (11.30)(2560) C1/hr (5-14) 9 A, = 482 Ci/hr (5-15)
The iodine removal time constant due to the leak flow is (60 min /hr)
(5-16) a=
y g,)
\\
"
- 6.
Os (
.51)
(5-17) a =.5209 hr'1 (5-18)
From (5-8) the offsite thyroid dose is D =
I x/q 8) [e"* i - e f])
(5-8)
Substituting with the spiking activity source gives D = (1.49 x 108)(482) (6.3x10 )(2.32x10" )(1-e. 209t) (5-19)
.5209 with tg = 0 and tg =t
~
Assuming a 10 minute operator action time, t =
=.167 hr 1 D = (.jt016)(1 e (.5209)(.167)J (5-20)
D E.02 Rem (5-21),,
6.0 REFERENCES
1.
Letter, BWROG-8222, Dente (BWROG) to Eisenhut (NRC), " Supplement to BWR Owners' Group Evaluation of NUREG-0737. Item II.E.4.2(7) " dated June 14, 1982.
2.
D. C. Rennels, " Hydraulic Analysis Procedures for BWR Piping Systems,"
General Electric Co. NEDH-20363-13 September 1975.
3.
Engineering Division, " Flow of Fluids through Valves, Fittings and Pipe," Crane Co. 1957, Technical Paper No. 410.
4.
" Steam Tables," Combustion Engineering Inc., 1967 Seventh Printing.
t 10 -
.=
~,
APPENDIX A - SUMARY OF GENERAL EQUATIONS STEAM LEAKAGE RATE From Reference 2, the steam leakage rate through a single line when the pressure drop is small relative to the inlet pressure is 22 I).1/2
[.
t 992.1 v da-ksP 9) p-344y g
9*
4 fd )
(A.1)
Ks + /h,-)1 1 l - }v v
3
\\v ) (d l V
a g
where the subscripts "1" aad "2" refer to the conditions at the inlet and the outlet of the line, respectively, and the bar represents an average value of the parameter between inlet and outlet conditions.
BREAK FLOW RATE The flow rate of high pressure saturated water required to produce the quantity of steam, q, is 7.4805 yfa Q"
9 b
-vx (A.2) where h
-h g
g x*
h
- 9 (A.3) 3 NOTE:
Subscript 3 refers to conditions in the primary coolant.
ACTIVITY OF LEAKING STEAM The activity of the steam leaving the line which was produced by the flashing of the high pressure saturated water with activity, a, is a f,(1-e )
f A=
q 36.74 v (A.4)
A-1 m.
RESISTANCE COEFFICIENTS Resistance coefficients obtained for pipes for different diameters can be related by the expression
[d,)*
K, = Kb
~
(d )l e
(A.5) where K = resistance coefficient relative to d K" = resistance coefficient relative to d' b = internal pipe diameter '
b d
The effective resistance coefficient relative to d, for a parallel piping arrangement of "n" pipes is n
a"d E I#K (A.6) 3
a y
which reduces to n
K,c [I I g.a i=1 (A.7) for the case of all K being associated with diameters dj = d,.
The resistance coefficient is defined by the relation:
Ap
- f
\\.
3 W
(992.1 d
(A.8)
The resistance coefficient can be alternately expressed as:
Kg = f(L/d)
(A.9) where f = friction factor L/d = effective length to' diameter ratio and f = f(Re, c/D)
The Reynolds number of the flow is Re = 378.3 (A.10) v d
\\*
p) 4 A-2 w
--. m.-...__
The viscosity, p, can be obtained from Reference 3 but is approximately 0.013 cp for saturated steam at atmospheric pressure. The friction factor is plotted vs. the Reynolds number and the pipe schedule number in Reference 3. although it is obtainable from many other sources.
Several typical resistance coefficients are
- K,g =.5 K,, = 1.0 K, = 20f KC = 20f (A.11)
DOSE cal.CULATION The site boundary thyroid dose is t
D = f,I A (x/q) $l dt (A.12) e An equivalent site boundary dose equation is D =:2 A (x/q)) i) I At (A.13) 3 c
j where the subscript "j" refers to a specific time interval for which all of the parameters are constant.
COOLANT ACTIVITY The time dependent coolant activity is a(t) = [a, - 5,/=] e
+ S,/=
(A.14)
I I
(bf a) + AaM
= constant (A.15)
W re a = ---
p
""o outflows
~
5, = h I ha
^
= c nstant (A.16) o inflows, 4 3.59 this assumes:
1) reactor coolant is well mixed 2) reactor coolant inventory is constant The average coolant activity with a constant source (5, = constant) is 1
[a, -
] [e 1 - e"t ] +
(A.17) f a=
=(t -t )
f y which can be simplified to
[,
I g,-= t,,,-=tf3 a,
=(t -t )
(A.18) f 4 for the case of 5,= 0.
A-3
.... - - -. ~..
~-
If the time dependent coolant specific activity is used then the total leakage will be limited.
If the coolant specific activity is treated as a constant then an upper bound must be set on the total activity leakage.
This upper bound is the total I-131 inventory. Hence.
- A IA*II)
A, = Ats D
where A
= 4.5359 x 10 M,a,
(A.20) ts g
(A.21)
AD* 88 All activities are in equivalent dose of I-131.
Only the portion of the coolant activity which is airborne can be released from the containment.
Hence the maximum releasable activity is A
I fl~"f)x (A.22) hax o p The maximum dose is therefore D
- A I INN) max II (A.23) aax Rmax c max which assumes all of the activity is released at the worst possible time.
A-4
r APPENDIX B - NOMINAL VALUES OF INPUT PARAMETERS Breathing rates B
~
3.47 x 10 4 mS/sec for 0-8 hr
~
1.75 x 10 4 mS/sec for 8-24 hr 2.32 x 10"* m2/sec average for 0-24 hr Technical Specification iodine concentration, a, = 0.2 pC1/gm g
Total Mass of Reactor Coolant M,= 6.5 x 105 lbm Number of Fuel Bundles, N
- 0*
B 95% Cumulative Probability Spiking, A = 3.27 C1/ bundle B
Thyroid dose conversion factor for 1-131 I = 1.49 x 104 rem /Ci c
B-1
F
.e
.s APPENDIX C - FLUID PROPERTIES h
P T
'f 1
f Usage
- 14.7 212.0
.016719 26.799 180.17 970.3 X,
15.7 215.05
.015736 25.490 183.25 968.4 i
16.7 218.1
.016754 24.181 186.33 966.4 X 3 1000.
544.58
.02159
.44596 542.6 650.4 X3
- Usage indicates how the different conditions were referenced in this
- report, i.e., X is for inlet conditions, X2 is for outlet conditions, Xs is for conditions in the primary coolant and X is for average conditions.
i Properties from Reference 4.
C-1 0
?
- - - -.