ML19332B243
| ML19332B243 | |
| Person / Time | |
|---|---|
| Site: | Three Mile Island  |
| Issue date: | 08/07/1979 |
| From: | BABCOCK & WILCOX CO. |
| To: | |
| Shared Package | |
| ML19332B231 | List: |
| References | |
| 86-1103585, 86-1103585-00, ISSUANCES-SP, NUDOCS 8009260340 | |
| Download: ML19332B243 (9) | |
Text
.
O Docket No. 50-289 (Restart) i Licensee's Exhibit No.
g\\71/
g, . ; 'ftEL&TED CORRESPONDENCE y SEP19 g , E Ctfict ci the twq Docketi.1g & Sergice //
% Bruch h) N B&W Document 86-1103585-00, " System Response to Total Loss of SG Heat Sink,"
(August 7, 1979) i o60 s
. SYSTEM RESPONSE TO TOTAL LOSS OF SO HEAT SINK
- 1. Introduction An analysis of a complete loss of feedwater transient accident for the 177-FA lowered-loop plants has been conducted. The analysis was perfor=ed utilizing a " realistic" decay heat curve, and assumed that offsite power was lost and that. the operator actuated one of the HPI systems at 1200 seconds.
'2. S m rv and conclusions An analysis of a complete loss of feedwater transient for the 177-FA lowered-loop plants has been performed utilizing a " realistic" decay heat curve. Cen-sistent with the operating procedures, it was asse=ed that the operator would initiate the HPI system by 20 minutes. A single failure in the HPI system was included in the~ evaluation.
The analysis demonstrated that 1 HPI pump provided sufficient =akeup to pre-vent core uncovery. The ulti= ate heat sink for this transient is the contain-ment via energy release through the pressurizer safety valves. Since no c. ore uncovery occurs, cli dding temperatures trould remain. within a few degrees of' the satuated fluid temperature and no cladding rupture nor metal-water reaction occurs. Thus, the criteria of 10 CFR 50.46 is satisfied for this transient.
- 3. Re'sults of Analvsis -
3.1 Method -
I Since the system response' for this transient is relatively quiescient, detailed noding of the primary system is not required, thus, the analysis in this re- .
Port was perfor=ed using a six-node CRAFT model to develop the history of the reactor coolant system hydrodynamics. Figure 1 shows a sche =atic diagram of the model. Nede 1 comprises the cold leg pump discharEe piping, the reactor vessel (RV) devnco=er, and the lower plenum of the RV. Node 2 represents the steam generator, primary side and the cold legs suction piping, while Node 3 represents the core, RV upper plenum, and the hot leg piping. Nodes 4, 5, and 6 of the model are used to si=ulate the pressuriver, containment, and the secondary side of the steam generators, respectively.
t k -
i
86-11C3585-00 The assumptions used in the analysis are listed below: .
- 1. The reactor is operating at 1022 of the stead;-state power level of 2772 MM.
- 2. Loss of main feedwater flow to the steam generator occurs at time zero.
The auxiliary feedwater systems are assumed not te operate.
- 3. Offsite power is not available.
- 4. The reactor trips on high pressure at 2300 psig.
- 5. No credit is taken for operation of the PORV.
- 6. The pressurizer safety valves start to open at the set pressure of 2500 psig. They are assumed co be full open at 1032 of the set pressure.
- 7. The discharge rate through the code safety valves is calculated using the Bernoulli equation, for subcooled fluid discharging through the valve, and the Moody correlation, for two-phase or steam flow through the valve.
The flow area utilized for the safety valves was chosen such that the -
Moody calculated discharge rate, for steam flow through the valve at the
~
valve rated pressure, is equivalent to the design capacity of the valve.
8.
Actuation of one HPI train, via operator action at 20 minutes, is as'sumed.
A single failure is assumed which renders the other HPI train inoperable.
Operator guidelines specify that, upon loss of SG heat sink, he should manually actuate all HPI trains.
r
- 9. In order to simulate a realistic decay heat curve, 1.0 ti=es the 1971 ANS standard was utilized.
3.2 Results Figures 2 through 5 show the transient system response for this accident. The ,
following table presents key results of the analysis:
.- Secuence of events ,_ Time, s ,
Loss of main feedwater, turbine trip, O.
' loss of offsite power (RC pumps coastdown) t Reactor trips on high pressure 8.
j SG side inventory boiled-off 100.0
- i. Pressuri=er goes solid t 350.
} Two pressurizer code safetics open 400.
l Long term cooling estab. (based on 1 HPI) 8900.
i j 5
- 2. .
86-1108585-00 Figure 2 shows the core pressure transient. Following the simultaneous loss f '
of main feedvater and offsite power, the fluid in the RCS expands due to de- '
5.
creasing heat transfer via the steam generator, 9.ed the RCS pressure increases.
At 8 seconds, the high pressure trip setpoint (2300 psig) is reached, thus ' -
causing the reactor to scram. Pressure then starts to decrease due to con-traction of the fluid in the RCS caused by the decrease in core power. At -
100 seconds, the steam generator inventory has been boiled-off, which results in a loss of heat sink and a heatup of the RCS fluid, and repressurization of the system. At 350 seconds, the pressurizer becc=es " solid," and the system pr' essure rapidly increases to the code safety valve set pressure of 2500 psig.
The system pressure remains at this value for the re=sinder of the transient with the safety valves acting as a path to the ultinate heat sink of the RCS i for this accident, i.e., the containment.
Figure 3 shows the pressurizer mixture level response for this accident. The ~
initial pressurizer response follows the same behavior as the system pressure transient. Due to the loss of heat sink at 100 seconds, the pressurizer starts to refill and becomes solid at 350 seconds. At 2180 seconds, the liquid level in the primary system falls below the surgeline entrance and steam passes into the pressurizer. Shortly thereafter, the pressurizer mixture level drops slightly and steam exits through the code safety valves. The pressurizer re-mains in this condition for the remainder of the transient.
The RCS liquid inventoty, with .the 1:clusion of the pressurizer, during this transient, is given in F# gun 5. Makeup to the RCS was initiated at 1200 seconds via operator action to start one HPI train. The RCS recched saturated conditions at 1725 seconds, and rapidly starts decreasing in inventory. With j
the liquid level in the primary syste= falling below the pressurizer surge-line nozzle at 2180 seconds, the loss rate in systen inventory slows. At -
i 8900 seconds, the HPI flow exceeds the core boil-off and the system starts to refill. At no time does the core uncover. Thus, the cladding tenperatures I
.will be maintained within a few degrees of the saturated fluid temperature and no cladding ruptures nor metal-water reaction will occur. O
\
i
~
t 1
l mMM "
.' FtGURE I v u = 1_L UGO O D = 0 ;O
- - ~
CRAFT 2 N0 DING DIAGRAM FOR SMALL BREAKS. . . . .
l (6 N0DE MODEU CFT .
Il 3 2 6 5
_ 1 _
. O -
1 O .
s
's s , @ :i c ;
LPI M m O s i
g O@ .,
- E
. LEAK PATHS 8 & 9 !
o.s m n @ ( ~,
m 'M a "U
,l I
.i 9
..Wes y e e I e e
- 1
- i. :-
t .
- s l
$ .. 1 1 !.
l . 7 ll 1'
an i
. n.o (g Q. Q p . n.. O, q ,
.. ... ._. _. .. . . ... ~ ,t N U td. . &,
e
..t.._.
. _ .......n..-
. .. . ... . . ...........,..s...~__..
__. . . . . . _ . . . . _ . _ . . . .. . w. .
._a.
.. . _ _ . ... . ._ . _- . _ . . _ . .. Q. .
... ..~.. . _
.,.. . ....._. _. . .. ... .__...r.--_.-r_._- .i._............_....._. ....._... ._..
_...._.. _ . ... .. . s*"
. .. . ...r. .
. . . . . ._ _ ..........__7 ..........._..
t . _ _ . .
....t.. . . . - . , . . . _ ... ..
.,=.
. _.... . . ......___L_.....
. . . . _ . . .. .. ... ._.. .. . . . .s . ... .... . . . s
. . ...r-..
...._.4 ..-
c.,........
. ... _ u..,. .. ..
,. . .. . . . . ....r._..._.
_ ...._.. . . . . . . . ......r...
. .. .. ~..
. s.. .. . . . .
a.
.......u..
. _ . . . . . . ..t.._
_. . _ _ . _. .._.r.-..._ _. . ..._.....__s._......
. _ _ . _.. ... .._ .. _._._.._..1._.
.._...t. __. .
._._ .. __. .... ..2_._._.
m .
. A .. .. _.. . .
.. _ . _ ._. _ ... _. .. ._. = . ..
. _. ..=__ . _.... ..y. .
. . ....._._.4..
.._. ..__. .=
....g .. . . = . . . ..
=
,a
.)...
'" .,_.s . . . . . . _ ....
Lt.1 .. . ..
t_. ._.
. . . ..._..n..._...
. .. ....... ... .. . . . . .Wy . . . . . . . .
.. s . ...< . .
__._t . . _ . . . . . . ,o.__
. . . .s .
..a
..-.... .W .. .
.n. . . . . . . . .. . . . . .
. . . . . . ... . .. _ _ _ v. . _ ....
...............2
. . . . .. . .~ .... ....
. _ . . . .._ . .... _.......r. . ._ .. .. .... _. .. . . .. ... ---.-. .. ...
- n. .
i .
_. 1 l
i i N -
o . . . ._. . .
i . ,
I Y
S .
.e Q
g.
n -
.i .
H n
-a a .
MO
- W.% Qd
'. \
%,1 0 D
y ,
~
l l
- O .%
gg .
.u.- M :a y . _
5 I
1
......; u u d.
L U UTO&2 O O * @
_ _ . . . . .* y e,s .... .. .
(..
.n 3 .... . . . . . _ . _ . . _ -
Y
. . . . _ _ _ . . .. .. ._... _ . _ ._ . . .. . . . ~
W .
. ag 3
, , . , ..f og
. .- - 9
. ... ._. ..... . c, .
s N
. + ...e . .__... .. . . . .
._ . .._. .. ., 4
.. .. H g.....-.........
.m..---
+
. . . . . . . ......s.
..4, 8
..4.. .... . .. ... . .
O . . . . . . .... . .. _ ... .. .. .._..L.~... ..
. .. . n
. .. .. .. .. .. .. . . . 4
. ~
.. . . . . . . . . . . . . _ . .i..s es
.. . _ . . . .. .. C y
w
%.e
- p. . .. . .. ..... _. . ..._. . .,.
6, :y
,oa ~
. . h o.. .
. . . . . .. . .. ......6 .
. . . =
. ... . . . , . . , .. . . . ... ... . . s.
8 ..i j
e .
. ,i 1
. . . . .. . . . . . ,e
.r .. ..
.g,,r ..
N
.y. ' .
. . l 4 3
.u,' .
. 4 .
a 888880
, 3= ..
. *1
.o . . a
..*4
...%... ~ -
. .. s. . . . . . . .
..- . - '! 2 <1 ? 7 2 Lfn.! X Zh{ '
l 1
,5 . ... ... . . O~ D' f ~ "
i 1
l 4 D D
. ~ oo3 -
y ;' . .=
q
- e
. h.b ' N ,h.h =3I .
'T.I
'-'- .- --" . * ~F"
. ""T- . '*
- .T'-. . . .- . . - -
- s OWD OO i . . . . me .}"J +W -
e.......
Q,U-Q,) 0 E2 %/ 4*/
r.
n ,,'1 ,
,. .e g
- 3. . . 4
. e.... .
. . ...& .. .. . .. .. . .e . . ~ . - .
3
... ., 9 %. .. .a.
. . . . . . . . . d
. Ai. . *.. J ,
... , . .e ... ,.
g h .e ..*W..M. . ..
g
. . . . .e. e
. * * . *.w.m. .m e
- 6. . . . . mee .m .
I..N.
.m m
=
.... g s . .. .. .- .
4 . .
p
. . . . .. = = . . . . . . .. .... .
4..... , ..
... . . . .... . . .. ...q..._ . . . .-..g. .
.h .
(. . .
. Le e
+ . . -. . . .-
t
..d ..
. --.. . ... .. .e..e.-.
b .
- . . . .- =
- r. .. . .
[. .
e..
p .
.s
.e.... . . . . . . .
p
.. . . -p......
$ .-. . = ... ,... . . a .
.. ..t.g ..
. . . . .. .a . .
...w w g
......wg. 6.. ...y e
.. .pm- --.
- m. . . . . _ . . . .m.... . .....
c ... . . .
. . . ... . . . ..s.. .. . . .. . . . . . . .
,,3 .. . .
. e ..' %
. . .. . . . . .e. .e . . . . . . .. . .e . .m m m.. e ..
. . ... g
.e.
> gg d
.........e.e
-..t ... . .
$,... M.W. . M - 6 * ...-..@
.= . . . .'. .. ...
a .. .. ...
.. ... . - . .. . . .t. .... . ...
D .
. . . . .s. . .
.g . .
.e. * . .
. . . ......m.=...e. .. e.
e
- m
. . ** g
. y e....e.
g .... .
M. .
. . . .N' . .. .
- . ...e . . .
,...M . .... .... . .. . ..m. .........I....
. b
. . . . . . . . . . . ... . . . . . =.= . - -
o p .. . e ..a .
(jl . ., . .I*.. .
. ..4 ....
,. .. . g -- .
j .
...t9..
.. . . . . -.6....W. . . . .-
..'...e.e.M..f.... ** * * "
".8..e...' * .
....e . . .....6 . .
y..6m.. .
p
. ..*.. .. .. .. = .*. *. .* .
....... ... . . . ..e.. - . .
b I ... .
r----- -
. . ...c ...
. 4M. .
g s
Q .= .. . . . . . . . .
.. .. .c e.
- t. -- ... - - . 4 o . . .... .. .... .. .. .. . .. . . . . ....
.C.
....J
. . ....m... . .. .
. ...M. .. . = . , ..~..&....
...g... . .. ... . ...
ww6%.6gm h.
h w w . .. r.e ee. . .. . . ...gm..m
- g. h .
. g h .*
.m
............+.h..9 .m.. 6.m ye
. . . A . . M' " . . .
. . ... . - ....... . - . .4.e..e.4......h..._..
. .e .
. "T***
...m.. .... .e
[ .
g .
g
. . e . . . . . .. . ... .. . . - .9e. . .. e . .
- . .e e ...
O. . .
g
...M .g
.......... . m .
. . ..g. . . . .p._...
..m.. W m e.g . .. .p ..M 6.
N '
W..W MM..
- 6.. m.e .
a
. ... .... . 8 ...
. . . 30
...3
- m. . .
.,,,,e ...... . . . .
4,
. . . . . .. . . .e-.. . . .. ,. . . ...
.* .. . e..
U. . . . ... ..
.4..-..... .._4-...... .
............e.e e.. .
.. . . . .. ~.. ..,.. .
,.. g6. ..
t e.. .. . ..
a
.. .e. .p. . . . ...
... . . . . . . . . . . .. . .e . . . ..
g"..
. . g 6... . . g .... g .
ggg .
g.g. . ,gg g .
g 090 g...e..
4 .
M
,=...e6*-.* @**
. . .. . Y.
a
. * . ..*f . ...
. .. . - .,6. .... .. .
%.f
- 1. .
. ... . . . . . . ... g. .. . . .. . -. . . ..
..p .
g *Z ,
i
. i. .
.-.g -. . . . .
.g l
."* . g y. .
.p., .....* .. .*** * . . . , e., . . .i .. .
M. . ** . ..* * ... . a
- g. p
.e.<.'*...
g .. .
6'* **e* * " .... * * * *. .g. " . .
...e.... e.
. . g .
. g p . .. . .
, - .... . ... . 3,. . .. . .. . .. g .. . .. .. . . . . . .g . ... . . .
w
.... m. . . . ...q ..
. . .. .. . . . . . . . .. .. . . .. . . . . .. , *T
..,..-=.. b...
. . .. .. . , '.... . . . . . .g . . ..... . .. . . . , .
8
.. .)..
.6
. . . ... .... . . . . .l...I..... m .... .
.. .., .. ..........,..O....
. .. . . . . .....i....
e . -.... . .
- g..-. .
wg 8... ... ...
.. . .. .3.. .. .. , . . .
. ....3
- p. . .
p..
e.
. .t.... . .... . . . . . . . . .
. . . _ . .1. .
cg
-.y...
4
. .i . . , . . % . ..
.,..y..
g e .
,f
.g e
$.. . ...e * * * *
.*..M g * . . .g. gg N. . . . . . .
- g
..N.h... m
+W..MW - . . . *..M*O M . .
g 9 . ..a.. g
' . .. ... .. . b. .. . . .. e . . . .e .
... l g . . . . .
a f ' '
rA 9*
- v 4
b.
Q
] % ' *.9 ] h M '.) ',.NC**) C),,, (110"L qin),.y 3 *) R N )
--T - -
y W'.--
. h[kw.
__qg-I i
oOVa "'*J, ,g, q D oo.Oe" p o,vO
- b c t o '
%d
.n . . . . . . . . . .
. ... .....-......g . u. . . . ... . .
g
, . Q 8
g .,e.
ggg y . . - . . . ...
c,. ... .. g C,e .n 9 - . .
...........-g
, 3 y __ ,
... . . _ . . t,.
. S. . .. . ..
- n. .g .. .. . .. . . . . . . .g ,. ..
g e .u. . ,-
3 . . . . - . .
. .. i. ...... .
p 4
. .l. .
g..... . - . . . . . . . . .... ... .
. .. ..........a......--..
.....I'....
g
... . .i .
4
. .st1
.I . . . . . . . ,l . _E.?
l
.. . .....6.....
.. q
. . g
..g ._.. .ag
. ... . . .. . . . I h
. s
. . .. . . . . . ~.. . .... _ . . _ .. . . .. . . . _. .. . . . . . . . . . . . .
. . . . . . . . i
. . . . . .s .. , .
.........l.
. . . . . . . . . $ .. . a. t 9'
g
. . .. . . g
. . 1 O ..
. .E.
g 0 1
u . 5 L 3 1 .. . O -s
. I
& = 0 **
8 n.
- a. .
a 4
.. . T, -
k i ('*% O '"
P
' D ("'"%.D D 3 ] '
. uf dT.' a ~~ -
"P*'.g.=
- N gr .F - N