ML20065C542
| ML20065C542 | |
| Person / Time | |
|---|---|
| Site: | Kewaunee  |
| Issue date: | 09/17/1982 |
| From: | Giesler C WISCONSIN PUBLIC SERVICE CORP. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| CON-NRC-82-163, REF-SSINS-6820 IEB-80-04, IEB-80-4, IEB-80-43, NUDOCS 8209240099 | |
| Download: ML20065C542 (7) | |
Text
{{#Wiki_filter:c , NRC-82-163 WISCONSIN P U B LIC S E RVICE CORPORATIO N P.O. Box 1200, Green Bay, Wisconsin 54305 September 17, 1982 Mr. J. G. Keppler, Regional Director Office of Inspection and Enforcement Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137
Dear Mr. Keppler:
Docket 50-305 Operating License DPR-43 Kewaunee Nuclear Plant IE Bulletin 80-04: Analysis of a PWR Main Steam Line Break With Continued Feedwater Addition References (1) July 15, 1982 letter from S. A. Varga to C. W. Giesler requesting additional information on IE Bulletin 80-04. (2) May 7,1980 letter from E. R. Mathews to J. G. Keppler providing response to IE Bulletin 80-04. In response to your questions of July 15, 1982, (REF. 1) we submit the following information. ITEM 1 REQUEST 1. Provide the estimated runout AFW flow to the affected steam genera-tor. This should be determined from the manufacturer's pump curves 8209240099 820917 PDR ADOCK 05000305 G . c SEF 2 0 082 PDR & v ll
.. .~ - .-
Mr. J. G. Keppler September 17, 1982 at zero backpressure, unless the system contains reliable anti-runout provisions or an actual backpressure value during the MSLB j has been conservatively calculated. The estimated runout AFW flow to the affected steam generator peaks at 610 gpm, 160 seconds into the accident. The flow was determined from iteracions of the DYNODE /P computer code. The Dynode code calculated the S/G pressure and break-flow, which was subsequently used to calculate the integrated energy addition to I containment. The AFW flow rate provided for the DYNODE calculations were determined from the combined maximum AFW pump flow and later split according to pressure differences in the two piping trains and steam generators. The maximum AFW pump flow was determined from the pump manufacturer's pump curves at the point of minimum head - maximum capacity. REQUEST 2. Provide an evaluation of the potential for exceeding containnent j design pressure using the runout feedwater flow rate determined in Item 1, Request 1. Justify any assumptions made for this eval-uation. We have concluded from our analysis that containment design pressure will not be l exceeded, using the runout AFW flow rate determined for request I above. Referring to the attached graph, it is evident that energy removal from contain-
- ment is always greater than energy addition to containment.
There are a number of conservatisms in our analysis which provide an additional margin of safety. These conservatisms include the following:
- Initially, the reactor is assumed to be at Hot Zero Power to maximize the steam generator inventory and energy content.
l l l l l
1
' Mr. J. G. Keppler September 17, 1982
- Only one train of SI is assumed available, to minimize flow of boric acid to the RCS.
- The main steam line isolation valve is assumed to close in 10 seconds. This allows both steam generators to blowdown for the first 10 seconds. (Refer to figure 10.2-1 of the updated FSAR. The check valve should actually prevent this from happening and the stop valve should close in less than five seconds.
However , no credit has been taken for this.)
- All fluid exiting the SG is assumed to be dry steam. Consistent with the FSAR methodology the energy release results calculated by the DYNODE /P code were multiplied by 0.85 (Reference FSAR section 14.2 - 35a).
- All three AFW pumps operate f rom the start of the break (at runout flow) and continue for 10 minutes: Main feedwater is isolated.
This last conservatism is particularly noteworthy since the third AFW pump (turbine driven) will not be started unless there is a loss of offsite power, or both steam generat. ors have reached the Lo-Lo level setpoint. How.4ver, we have assumed all three AFW pumps are operating at the start of the accident. REQUEST 3. Your submittal of May 7, 1980, takes credit for operator action to i identify the affected steam generator and isolate AFW flow to that , steam generator within 10 minutes after the start of the accident. l l Provide the tasks to be taken by the operator to identify the i l l affected generator and isolate the AFW flow and the jusitification i for your assumption of 10 minutes for these actions. l l l
7 Mr.-J. Go Keppler September 17, 1982 _4_ As stated in our May 7, 1980 response, and reiterated here, the assumption of operator action at 10 minutes is justified. The operator action is the iden-tification of the affected steam generator and isolation of AFW flow to it. The operator will be alerted to the affected steam generator through a number of redundant signals such as, but not limited to, the following: a) Feed flow - stean flow mismatch b) Feed flow mismatch between the two SG's. c) Rapid steam generator pressure decrease in the affected generator d) Increase in steam flow downstream of orifice e) RCS temperatures decrease f) Decreasing Pressurizer level and pressure g) Increasing (or high) containment humidity Given the number of redundant alarms and indications, the operator will be able , to immediately determine the affected steam generator. We have assumed a 10 minute time limit for the sake of analysis only and are convinced the operator 1 will actually implement corrective actions for the affected S/G much sooner. The operator is required by our Emergency Operating Procedures to perform speci-fic actions subsequent to identifying the affected generator. In the case of a MSLB, the operator must close a motor operated gate valve in a common cross con-nection line and trip the respective AFW pump. Both of these actions can be implemented remotely from the control room. Hence, the 10 minute assumption is conservative and can be adequately met by the operators. REQUEST 4. Because in your analysis you are relying on operator action within 10 minutes to mitigate the consequences of this accident, provide the time to exceed the containment design pressure, the time to reach peak pressure, and the magnitude of peak pressure if no operator action is taken.
r Mr. J. G. Keppler September 17, 1982 As noted above, 10 minutes is used as a point of analysis - our operators will be able to identify the affected steam generator and isolate AFW flow well within this time limit. Furthermore, as shown on the attached graph, and already mentioned, containment design pressure will never be exceeded during the accident, since energy removal is always greater than energy addition. In fact, the containment heat removal system's capability gets increasingly greate'r'even though the energy addition rate remains relatively constant. Since the containment design pressure is never exceeded, we, considered [t unnec s essary to calculate the time to reach peak pressure or its magnitude. It can be . A seen from the attached graph that even if the operator failed to act within 10 - V ,,- minutes, containment integrity would not be challeng$d for two'le'asons: '(1) The s , s c, ' critical portion of the transient occurs in the first minute, because.ot-the
. 3 ,
high energy in the steam generator blowing down to atmospheric pressura,out'theb , s, , ( break, and (2) the energy addition to contai' ament ~ becomes relatively cokstant" ,
)
with time while the heat removal system's capability rapidly grows. A" , ITEM 2 _- l x < mm REQUEST 1. Provide the estimated runout AFW an:4. MFW flow to the affected, steam- ,s w- , generator during the MSLB. This'should be determined from ,th,e. [, , ,
, w y s
- . .- u .
manuf acturer's pump cutybs at zero backpressure, unle'.su the system - r~
%, s , y contains reliable anti-rufout ptLvisions or in actual ~ backpressure ' \
l '- ! value during the MSI.B lias be'en connervatively calculsteds S '
\ ,' _, _-~- '-y j 's . --,
s Refer to our Msponse for ITEM 1, REQUEST 1. In' addition, note that at HZP con- 4 s s - 3 ,, , ditions (consisM nt with the FSAR methodology and nnrmal operating pfadti2e) ,
~
\
there is no Main Feedwater Plow. % ^ 3 ,_
's N% ,,
e
. .- ,, v 7
e l ..
3
, Mr. J. C. Keppler September 170 1982 REQUEST 2. Perform an analysis of the core reactivity response to a MSLB, con-sidering the feedwater flow rates determined in Item 2 Request 1.
Justify any assumptions made for this analysis. The DYNODE /P analyses have shown that core reactivity transient results are very insensitive to AFW flow. All DYN0DE/P reactivity results are bounded by the FSAR analysis. The first minute of the transient is dominated by higher steam flows contributing to primary - secondary heat transfer, which is the forcing function for both the reactivity and the thermal-hydraulics in the core. Conclusions We have concluded that the integrated energy addition to containment is relatively insensitive to feedwater flow. Although we increased the AFW flow to the affected steam generator nearly 50% from our previous analysis, the integrated energy added
! to containment ; hanged less than 4%. Due to the large initial steam generator pressure and inventory, the earliest portions of the transient are the most critical and are only slightly affected by the runout AFW flow rate. In fact, the higher AFW flow in this analysis, reduced the energy added to containment slightly from our May, 1980 analysis. This reduction in energy added to containment results from the cool AFW temperature reducing the pressure in the steam generator which, in turn, reduces the break flow.
i We have concluded from our analysis that containment design pressure will not be exceeded by a MSLB with continued AFW flow at the runout rate. Sincerely vours,
~'
0h f &c ^ C. W. Giesler Vice President - Nuclear Power i ja l Attach. j cc - Mr. Robert Nelson, NRC Sr Resident Inspector { Director, Office of Inspection & Enforcement i I L
3 O O iJiT';.is T*: T - >> O
)
. o s q.Ip-ij f ,. jg- i %4i._ +r .-
_.t F t+.'t
...q . . . _f.
--s i . .
i i s&. .e q
. t i j r,1
,.. . _.g T.! t t '
--+-t._-
t-J%+. _1_1. _. _7 i- i.
; - &. -.,-.4.
2_. -,t
+ .
_.t._7 , [ 4 4_L T _ ;_; j_._.Mi - r. i ; i ig
'~ ,-
p o 7 d' 4 r4d- !' 'I I- 'l -- O;- d. -- ---+-~+-t
-4" i 2 f - ;-H-} 4 -H L l}4 --- --b{ ' ' -
- a s L .L. _; . . + + l-.} -- L._*.- ..-}- .--P .. a- L.- _L.s.:_a. -& }- pas ;._ _4 ,L ..
S y y. . . .
. y -.
.......,..r' . . . ,,.... . .
y , ;y
* ; : l.... ....,
q ~7 m3.... ..g-+-~ p
-~r --
. ; 7m-
' E'! ,! ip % j +'.._ .
.1. _._ . _ ga . 5
- iI.* .i
. ' ^i , i ! l' t_';
'F '
!- ]
4 .~ _qt- a . 4- a u4ay .. _. 4 a. . . . 2 __p...,.. _ , . . - .a ji ! 1 z- t t
- f- f , 1 3
y .1 -
~ ' +-- NHI-- J 3 i-- J --t p '-' f +-! , ' , { +- ~~
-- - b L-a 4 . . .
. _ . . - .. .a. .;
- . t .
- t. . L... _. . .. ,
. +
m .. _.._ . .
.. . . 4 ._. ,. . . ... . .- .. . ..
. . 4 4 .. . .! - t .. . _., . . . . . . . . . . - .
..J,..,..,_.._..1,-
, 4 .. _._ . . . .
..L_ . , , . .
. . . - m ..u 4
_...,.4 t
. ._.u%
a .,.. ..J
. ~. . ._
.1 s..
- u. . . . ..._.aq
^,-e.- m~.._...;
. . 1 . .2 . . _ .
.1-..--.. 4 0
-t O t ~ - - ~ .~~r , e . . . . : -,m
-mm ,
I. p _ f . .. .
. 4. 2 , . ii .L _h.. .
._il. .. y i_. !- . __ i L-_. .b '_ 1 51I '
-t k: O 4, 2......._.. . . - - . _. 7 . ,- __ 7. , .7 . . ., . . . _ . ..y.. 4 _
? t - * =
. . _ q- .1._..a_.,.' _ ;_ L:_
y Q ' { _. .n- ._ _a.4 4 .
.._g 4._3 . :r {. ._;[ . . 7 . .;
.- g
_ . ._4 . __} __{ _ p 14] . :. . l ._ , ;. 49 - _ _ p 2 .. 1. __ p . 4 . .: .. _:. ; . p.'_..._.! g ' t . ... .. : . .. -f. '. 3 .....-..._-{.....,....-~"-'+--~'7;,~** 0, ,i..' 1
.-,--,. . .!... t. ..
,r,..
. .-. l . ..e g4 . -
. 4 -v ;
-.rt-v'"* * " - '
- -'1 ---'--*--'-'.'-8--*-*'--
}!ll j' i! ..,! $ i_ ; + ! ,! , [ l ' l '!.l' ge .
5 f i i~ l ' t t 1 i i. ' ' : I t i 8 : "1'1 4
- i j tr a j I-a i .. - a .._._ . !
I l . ! I ot ._ , . _ _ _ , .
. . .i_v.
,: _ -- ~.~ ., ,,_ -
, , ,- ,,' . . _ ,s + --- r i
1 i~ u .- , t ,
', 4
't i
- . .i . g
. + 4
- i. 2.I tj . I i-e ,.
[ a'- ^
-f.;_.- F ._;.4 ' L.j_ ; , . , , . : _t-i. } h- .:_4 i r - -Y !-
. } _j- i -._
a{ w "t-
+ * + +
. . . + ..;.. .
* ; 2:
ca m $:.4 m .a.* ~ ~ _ h. 2*J' i.. *-_. e I
. .....,i, + . . ..
- * * +
! , . ,- . ' i t.a t., l... ...
+ - . .
1 e..--
. . 4 i.' - *. - .* -- ' -
+.. .
O - - ~ ' . - * " , - - - - - * ~ - - - , - ~ - - * - " - + - - - * - - +, '- - - * - ;
. ! _. .. "y"
i....!
+ - . - .
4, . ...- . . ,-4 ,
. )
i ! : ..p. - . - - .--
..+._..
O
, .. 4 -4 4, .
._+.-.a t ,
, +-.
4 t + Z { t _. .. . -v , . _. 1- . O
. . } . - ; . . O
{ l i . . . , 1 -j Ow T i y,7..__..__.-. ,,,_4_,...,_. _, , 7;, p.-. . , , ,__ ..
- _ , _ _ _ O y)
/ o + + . 4 .i . .- - m.~.. .. g_ m_g +.g. .w . : 7_ , --
.t . .. :_.. 7 _
_4
' -.4 - _ . .
o 4_ p' M _ _ . . _ ...a _.i_. O . ._;....._._ _...'i. L 14,_. ! i .d._ M ~
~p' i i . . _ _ . W*
.M gM.i_r.
., ,_: 2 1.
q.._._._ -
. _ .i _ i _ , _,! ,:_. :: _;! !_i i i.. .-..y_'_.. ,
...__ E_
1
$ [ c -' . '. J _b.
. . ; _ .- _ _. .n b. . . : _.1.;.L; _. :. . _; . . .
3
;_ . __+
b
- p. . . 7-. .. ..., , - - . ,.-.!. . , _ . yt...._ _:
- q. :
i . t-
.-_p 4 w - , i i i 4 - : : 4 : : . > ,j i ;
tr U_ E 4 :
' t - I 7
,' i. i j ' ! ' : I p.-
I -
---.7.-.!._ __.4i _ +
.q. ^ ,
I - - ' OyI9
. .!
- r'. 4 .
i, a! I, .i 3 d .1_ ' H _. i ,' l_i L -_ -
-_--E N4 ) @u QW ., .
4 . ; y u .3 a- . . f. , Ya eoe C re c., *
- 1P . '
- j . - -
ofu C C m a x -
.i _'.-
D p g g g g 7y s. t 2 . - - + -
+
,y Ix u u cQ . . .t
,mm W .c A. C O 3 g o O
-
- I-
+
. '.- - * + '
a w W u otg ,
. 4 J, . . . 4 5 b, U amM O C O ON oa h$$ ,
* ' ~
f
^ '
wuum. , r ,. j . . . . i r1 O u .O W O C g . ; ucm aw x yo
. t, S, ; +. . ..
1 bO C C t+ --
! t, . C - b T"- -
"T- ~ b o u4 O Ot ]agy o"* P. ; t:L. .7e-b - + - herri- + ++"r -- - .2_-y- +-r r i j
-~t-+-*~
+r'
, u m xc u
@ wuo u C t
P M -+44.g-+. - i .
-r .-y* . . ----"d-+:-+:".'-- .
~
'.~L -
3 : 2! g .uggwyagw=c nib....j
,. p : : :
I
- t. =
""4 5 "O
- 0 h {. . .
0 -4 0 t e -1 f '_ t: -_,_- G .'D r4U o c3Ue-4Gcg -
"- .Ce4 cx x .:d c gg uO g3 7: ',. . .
7.. !I
, ,--,~,-r- -.-* 7,
'p- , ~
r-q'--- c40 McO OUM > , i - l ;
.'.,, i :
a u c g y u oy m uo ac 1 a+ t! .u. 1: i . t i *{
- U
+H. ,
.i O D C .O C ! r ' ! ! , i !
OmO W WO -
, t ; ; :
Og c3
- h . : t:
3 g g g U M; _ -~ n.
. m -d. . +- W , .
. ~
.. u .ae4 .. .re e
> 0 u ;
4 w m3 y gy ua0 3 1 :> x :. Ud I t . : ! M mm M Eu O.. ,l _ . . , ; - '. .t. : a C a ca -+
) :
.-.l
.i U MO V
}'.'.
O u l . !
.C H y; u c .. 0 4-
. 4 -
t . e a 3 I 4 . . y , e .u 4 t lg ,4 g m .g u + > +i t 4 t'- - om .c uo .9 ' l t
* ' ' + *
!m
.a oe a *w m om o oo ~ l; !
t I
'l i t -
,!--- l t I t O O O O O O O O O O O O O N O W W T N n18 901 A983N3
- - , . .-- _. ,}}