ML20209G637
| ML20209G637 | |
| Person / Time | |
|---|---|
| Issue date: | 09/08/1986 |
| From: | Congel F Office of Nuclear Reactor Regulation |
| To: | Hodges M Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20209E138 | List: |
| References | |
| FOIA-87-10 NUDOCS 8609150040 | |
| Download: ML20209G637 (25) | |
Text
's 4 Q UG g
i g' 'kg
, UNITED STATES -
NUCLEAR REGULATORY COMMISSION
$' E WASHINGTON D. C. 20555
\..... SEP 0 81986 MEMORANDUM FOR: Marvin W. Hodges, Chief Reactor Systems Branch Division of BWP Licensing FROM: Frank J. Congel, Chief Reliability and Risk Assessment Branch Division of Safety Review and Oversight
SUBJECT:
POST-ACCIDENT DOSES OFF-SITE FROM NOBLE GASES In your August 28, 1986 memorandum you requested RRAB to provide post-accident offsite doses from noble gas release in containment venting. The enclosed tables provide the relevant information which was developed in this branch using the MACCS computer code for DSR0's input to the RES effort to define a "large release" for the purpose of regulatory implementation of Safety Goals.
The results providea are for release of 100% core inventory of noble gases in a 3412 Mwt LWR for four different release scenarios shown in Table 1. In the MACCS calculation, one year's worth of New York City meteorological data was used; no offsite emergency response was assumed; and it was assumed that people receiving radiation exposure were in the state of their normal activities. For a reactor of different power level the individual doses and person-rems can be scaled by the ratio of the actual power level to 3412 Mwt.
Scaling of individual doses and person-rens for release of less than 100% of l the noble gases would also-be appropriate. However, scaling can not be applied to non-linear quantities such as early fatality radius, and individual l risks of early and latent cancer fatality.
Table 2 shows total bone-narrow person-rems within the 10-mi and 50-mi regions
! assuming a constant population density of 100 persons / square mile beyond an I
exclusion area boundary distance of. 0.5 mile. , Table 3 shows the distance from "the reactor within which potential for early fatality (probability greater than
.005) exists. Tables 4a-49 shows individual downwind total bone-narrow and thyroid doses, and individual risks of early and latent cancer fatality at seven distances (0.5, 1, 2, 5, 10, 20, and 50 miles) from the reactor.
Tables 2 thru da-49 show the mean values of the results (which are not expected to be substantially different if meteorology of a different site were used).
We have not made graphical plottings of the CCDFs. Therefore, without having the benefit of the graphical plots of CCDFs the variability of each result l
(in these tables) on the high side is indicated by statin calculatedlowestexceedanceprobabilitygreaterthan10gitsvalueforthe . Graphical plots ofCCDFsm3yshcwhighervaluesattheexagt10-3 exceedance probability.
(Conditional exceedance probability of 10- is judged to be sufficiently small.)
);bf CV8 T lo @t L 5 $ $ W M n
.t M. Hodges You may contact Sarbes Acharya (x29738), RRAB, for any additional information.
Ll; 0yl Frank J. Congel, Chief Reliability and Risk Assessent Branch Division of Safety Review and Oversight
Enclosures:
t As stated cc: R. Bernero D. Ross R. W. Houston G. Lainas L. G. Hulman E. Jordan, IE
- J. Martin, RES T. Margulies, RES a.-
I-l h } l l i
. -,.,--,,- y , - - - . . . _r.
. 3 . , . . _ , . . . , . , , . r_.y., ,,,,.-.,.,__...,,_,-,,r ,,- , _ , , _ , , , . . , . - . . . . . , . . , - . . . . , , - . , . . . ~ . -
- 2. ==e-U .. A- 4 .4 4 e 4 a8 w)%
94 a 2
'*}
g 4h e i m hl N
%' 3 0
2 <1\ 3 a
" A4 mv j -
+
dt h@. av m L k i Y {St St 3 $
~
&m b
N \
' o b .A d i s 6 6 6 t
to e at w pjk + - "
- e -
A 9 l 94- H e4 M 4 m
l
%MJ Totet %-Maneu fern-Quv de~ R6 of 1 0 0 #A in G h e h e Q o f h / r l> l e. k o m o
\/ahi % ke/Lxae SMMos (of Teffel) p u. SuA.
n , . f f KeIeaae . M 1og %. '& Qp4y
%*Wo Radiis Havm) ; MSn- ^p+w o
# (ni) Pasen-PDw at Wg facete like-(Measo ) Y 9al M10 of ik 10 1 37 (4)* F(4) .3 D (-3) i
% 3a&C4) 7C4) 1 27(-2)
Lo 1.n(4) SC4) 3 82 (-s)
.1 50 1 35(4) 7(4) 2 .16~(-2) l- -
-L0 1.1s(4)- 304) m 31(-1.)
3 So 1.08 (4) 7(4) g . gC(-3) Io 2 06 (s) 2.(4) L .1H-2) Sb 165(4) 3(4) &.51(-2) 4 l
- L.37 (4) = L 3 7 x io
TM B fr~ Glux . of
$?aAho 6$ %4 WJA/3 100% cd GnEk& 04 />&& Gens a
/et< ban RM Sub=1 (& TcLa &
f"""~ ,c w Reh S*6 Mb I *b d kPd#63TA wh
%b nun Pa% wt
\ cet &ybAs 9aat 4 ~ (+uleL)
X M . >/io-s t #e-6-(M & C@ L 6'" s cs)# .2. M c-2)
} f f f (~
1 3 251 3(3) f,3./ (-2) k
# 3 3(3) = 3 x /o
q
~
~~[e 4 6 4 L
. 3,, w ,Aat 9 w .h a a FM M b b r
% 62eluas of ing con pnq 4
'ua & m. a uemn Max % Mf/M')\
gxswa. % Raw:0 b%Qam Re % 1>el', 0h84*Doce, vaba s$ pre ?f, ara 4,s3af6 9m ' b Hsy/a4b & WsA.d n& 4 & P&.'?po W}i1' sn i2/5K (paf Me4*/l/-M t a ,. /*w& ^ L 'TH D0sc (R**) 2.32(2) 1100 .2 8 3 (- 3) Tl bok6%) ,g , gi (.2) 1,000 1 91(-2) 1 50 E0
$a F< hlb pisg 1.O 4 41(-2)
Y l2<h S' 44 C-2) V.0(-l) 3 1 12 (-1.) y TH 3kte (Rew) 3 13 (2) 1, nee i . 99 F2) h%d-kje(Rsn) 3 20(2) 1, eoo a . 5162) Sa f W b fisk 2 55(-1) 1. 0 f. t yc-2) W.Cun.llae (o 17(-1) 7(-2) 5. tl(-1) 3 2 77l ) 6~oo i.oi60 TH2)6te.0%[) 44 befel b. 3 35(2) 700 3.ggr-2) k~ 1.o 3.i s <-2) 63oC-2- 2 o C-1)1) 9(-2) g.c& pi)
~
g TH M% 1.12 / (1) goo 3,39-2) T ANd.Dnft '
.I . 72 (1) SUD i.3862)
Whh. l.de4.0Mw$Uk
- 3. ll4 Fl]
IIS3 [~*] 7(~0 /'3862)
~7(-2) 9 2e(-1)
t
~
Ta46 4A 7 ,, gi w a 9 w .'D s d n a h e X P a r
% Ph of .00% we- &nQ & 8
)(p f f d y x ,3 $ Vd21% W SMN h
<7)cska. frew Rea&: L M A ,s m RelD %
9@C
>> 04f4*Doh., vakz s$ pre ?f,.egag,syapti 4
& Hsy/al1b er Rt'sA.d ~
W o, & sn 12/5K & f m f. y /o' o lmeah4^' (tva) Hea*A!.~h ta.,n &
] TM Dose (Ree) 1. 0 11 ( 2 ) S co 1 3 8 &.?)
il belella-). 1. 2 &l2) SDO a kl 2)
$a FdcAb Pisk 3,78(-2) 1 61 & )
7 oc-1) Id 12 1 h c389 C-2) V.o (-2) fl41(-2) y TH 3%s.(Ree) 36I(2) 1 6tc-2) fu?A-kje(Gen) .1 9((2) 1>yoo
@o I 3 EC-1) faf Pc/rAb filk 4 01(-2) 1.&o I . 6 i(-2)
Y.(>(4fluk 3 8.SC-2) ?(-2) /.ogc-1) 3 I.3 3 I ) soo 8 2 4(-2) TMkfe.(1%[) T m'd b4Ce( J'47(*) 6700 /j,Ii(-2) Sq(ed)kik. b^. 3 8 (-2) -Y l-U /. 82 (-2) l , (.ac.Ik'ste - 3 ' 92 (-2)
~ 7 ( .2) / 22 (-1) \
g Tt1 baft%) 7 3 7 (i) ,2po 1 3 g(->) T 894(L) 2 av 3 . is-(- 2)
**d DefeQ Va'}ei}< Qisk i. o 9C -3) 3(-2) l 35(- )
W GanAbr 2. l8 ( 2) 7c-2) /. u(-2)
1 Tebb 40
~
Q'n'chuz2, }gctArt .A i 36kfe- O lI/Ybb 0k
% 62elt.aas 6S 1 M % co u. Sn q 4
'ya g,o e va% u- hw4/*2) 3rs/ema_ h k"*!M'E psa x rem 6pW 09 2&, vaba On FMasw& &
9a*c Qg +< WsA. d techa.- ~ +r (gb) w/Jp<b M l/~ f ^' f TMDose (Reu) 4 11 (.0 200 19S(-2)
. Tl hoje(4,.). 4 % (1) 30 0 / 38&2)
L RMbptsa 2.csc-3) 7c-2) W p<an 1 12 c-2) yc-2) 138c-2) 2 2cc-2) y TH3we(gee) 7 14 (D 3 00 s tyc-2) wa.w(u,) s 67 ci) sw 1 3 s <-2.) g% P+Ab{liSk
.(p %
Pise ! 72 (-1) L 9cV2) yc-1) 1.3gp2) 8 24(-2) 7 (-2) 3 y H y (gg , 6./2(1) 2eo 6 63C-2) T bge( 7 43(D 300 l 82 C-2) Q42 Ibuu. 3.g3<-9 7(-2) l e2&2)
, Cam.))(AstwI 7 ft(-2) y(-2) 7 72&2)
Tr1 bafe@e,, 3.99'll) /00 md p4e ll 79 (1) 2ec 5Irc 2) i 33 (-2) Wy'g/ 3 j. fr 7 (-A') /(-2) / 3ccc-2) WCmthu l oo (-2) isf-2) i 32(-1) l
. - ,. ,-- - -..,-.. , _ _ _ - --- _ _-- . ,_ ,--n,-- _ - . , _ _ , - - - - - - . - . - - _ . - - - -
TYk [,7pOn'chd }8101Af75A $6LSG- lY/Ybh k f++ W el D0% w e- & n & 4
)( & eM Ab WN $ h '
9)esku. frew Raw: s~ Mk , Rek SW' W 092m., vaba s$pu rphsw a hey &h $r h*SA.tt Vchar p; & Y M WK & frrd.7)/o (Ne) M= l/-h t a ,. fM W0 '1~ j TH. Dose (Re+) G.O2(0) W l'2 Y(~2) Tl M(fa,.). I ;2L (1) 70 3
- 81 l?)
74 f*N5h 9/Jk o o o U Pdk .,9 01(-3) 1 CC-2) 3 . <t 2 (~2) g TH14e(Ree 1 2SCL) too J.2 7(-2) hweLw(u) .,) 22&(0 io o 3,qu-2) y4ushene s. sses> s<->> z . e 2< .s> Lt.%llite 1. 1 2 9(-3) a c.- 2) l. 2 7 (-2) 3 1 G5(1) 70 s sic-2) Wd W TM1WeGew[) 2** l') /Go / W (-5) f=MJ/L3x. <> o o
.Cn.Wsu- 3 6i(-s) 2 (-2) 4.it(-2) 1 TH b&(12e , /.19 71) Sv l h T **d D4e 1.4 r(i) 7o "*
3, b'l,') W4)91h. O o o iJe4.C m lux 27 'T(4) i(-2) it (-2-) J l- _ . _ _ . - _ _ , - , , . ~ _
7a~Me .4e-. Tys%'churf. 'pectArrAA !DMe- & M/a/vAh WK--
% 6?elwas 6/ .00% core. o%vek 4 l
'we &w a w L&c Guf/w)l S cs k u. $wv Ra & :10 Mub g Re% erga~ W 091e2m., vasa spye 4%asqq+a 2c w 4
ggptsn torMb flisK w R<st d W~
& Pro d. y S o pn<c&+T^'
(Ne) Mu~ll'h t ,s,,,. o j mvese (ee~) .2.er(o) lo i t20 C-2) Tl M(fa,.). 3 o (/ (0) 2O 6 fi'b'F 3.) b Mh(2/3k O O O N' [2 3k 1 5' 33 (-4) 3 0(-b.) 2 03 c-2) g TN 3W:e.(Re*i) S 6S(0) 30 g.8Sc-3) h%'clkje(84n) & %(C) .s o 3 o6 c-2) fist o o c3 9.afWb{li3e Y .(> % .i . 0 6 (- 3) 5 {--3) 3 0ll-1) 3 TMW(f% S' l'(0) 20 2 !?( .)
- T nd htfe( 6 'bl(0) 30 j. 2 2 (-2) 0 O fr/A[3k-lA) &.lYS'k -
o
~
[]*$3(~4) $'(-b) /. H (-2) j g TV1 bolt % 4 //(0) to 4 3SY-2) T ^^*d Defe ' 5' of(0) It' S '3 <-2) hh h' A. J 6 C W % Ihr i(-a) s <-s) 2 .a? <-2) i
L TaA 6 A h reguA4 hveu ha " 6446 9<A fs, Pk of 90% core. pnw 4 \
)My(e $aot2 A l&21N 0<Atrwt SNMhM'I)
S ) c s k u . $ e w R u & : 2 0 M b ,g ReID% 1)el', Chfa*Dok., vala s$ bee 9" b HnMb u R<sr d Pf,. w gag,v;k;Ya 4 5 /2/5K W fdyS 3 />mah'y~ (N") Hea&A'- ta., & _( rnvese (Re~) 7.Sg(-1) 3 3 8 s(-2) ri yk(la). 9 3 S l-L) 5~ 2 02)
% F4Lb Ptsk o o o Y [2<3g 1 33 (-4) 7 0(-4) 2.og(.-2) y TH3 Ace (Re+ 3. b^1(0) V 2. gc-2) herLyjg(Q ps ,) .i . 96 (o) io 2.og(-2) bf Wh filk O o o W . % Rax D . 6'il-4) 1 (-3) 11 37(-2) 3 1 43() 7 2 csc-2)
TMhsten'd1k:(e %( /.77(0) /0 2. og(2) h3A. o o o
, b. Sk- 2 34(-4) I ( 's) 2 .ci (-2)
-g TH1kk % 1. 22.(o) 3 3 9sc-2.)
'l ~ M%'dDefg l l.SI[0) .b- 2.cg(-2)
O o \
'1%leip< Qbi! o W k luk 2 lf(-4) , (-4) 2. c e (->)
Ta b 6 4 8-5givichu.L '
'prowrAA .'DMe- "A /Z*dAh 0%K.
62e k 6S 1M% cota.&n & 4 ,
){pf f
&w $ l/ w 2 t h 0 < A u s '2 2 S Y N h W S)cska. $ew Rea&:6m Oths,s m Relo n boss 0!)go2m., vaba 42we 4,was,qofa 9m b
HsrW@ k Q< sA.d n+ 4 'sn 12/SK. W fd p/i yrk}i1 faw ( N") W""' V'~ twns.,u & ^' j rn vese (e w) s . 2 s(-2) o.3 't 3(-3.) rl y(p,.), 1. . o4 C-1) o. b~ 8 8sc-3) F4Ab Ptsk o o o id. Iz<3( / /ac-r) yc-r) s erc-3) y TH3weCRee) 1 6ll(-1) o. y 8.ev<-v Qwet yjg(ft,.,) 2 . oec-1) Lo 8 8S'c-3) fisk o o o 9afPcfrAb{li3k W .(> % 2 94(-5) l C-4) <j.i(-3), 3 TM W ()% l 62C-L) 07 2.ssc-3). TQwdbdel 2 . e& (~0 1. O g.gs r-3) h3k. o o o IA). %. Ek - 2 '10 (-S) lC-4)
~
Tt1 bde(/2c,., 9 3 (- 3) I SG(-1.) 0 6~ i. H(-2) h i n'd pde I
- 17 (-t) 0F 8'.8F(-3)
Iu'/ci)f h'JA o 0 o l.de,4Gwndhk 2 ? ? ("S~) 1(-4) g.w(-3) i I l l
. i .
$~
5
,l DISCUSSION OF A GENERIC LETTER ON BWR CONTAINMENT PERFORMANCE ,
SEPTEMBER 11, 1986 r.- ROBERT M. BERNER0, USNRC i ( i fdT/1- 2'l-o/0 6 6
- 1-GENERIC LETTER ON -
BWR CONTAINMENT PERFORMANCE THE SETTING: PLANT EVALUATIONS UNDER THE SEVERE ACCIDENT POLICY STATEMENT THE KEY REGULATIONS: GDC 16 AND GDC 50
- THE SUBJECTS: 37 BWRS WITH PRESSURE SUPPRESSION CONTAINMENTS l
THE METHOD: A GENERIC LETTER OF REQUIREMENTS TO IMPLEMENT l . CHANGES BASED ON GENERIC EVALUATION ( "********a .=-e .. .es a e.. e se e p
- a+ eo m.es , ,,, .
...n-n, ,_.,,,n-,,.___,.n,,,._,.-,-.n,-,,. ,_n.,. -
. 2 NRC SEVERE ACCIDENT .
POLICY STATEMENT ,, e THE MOST COST-EFFECTIVE OPTIONS FOR REDUCING THIS' VULNERABILITY SHALL BE IDENTIFIED AND A DECISION SHALL BE REACHED CONSISTENT WITH THE COST-EFFECTIVENESS CRITERIA 0 THE COMMISSION'S BACKFIT POLICY AS TO WHICH OPTION OR SET O OPTIONS (IF ANY) ARE JUSTIFIABLE AND REQUIRED TO BE IMPLEMENTED. e IN THOSE INSTANCES WHERE THE TECHNICAL ISSUE GOES BEYOND CURRENT REGULATORY. REQUIREMENTS, GENERIC RULEMAKING WILL BE IN OTHER CASES, THE ISSUE SHOULD BE THE PREFERRED SOLUTION. DISPOSED OF THROUGH THE CONVENTIONAL PRACTICE OF ISSUIN BULLETINS AND ORDERS OR GENERIC LETTE,RS WHERE; MODIFICATIONS ARE JUSTIFIED THROUGH BACKFIT POLICY, OR THROUGH PLANT-SPECIFIC DECISION MAKING ALONG THE LINES OF THE INTEGRATED SAFETY ASSESSMENT PROGRAM (ISAP) CONCEPTION. I e P
3 GDC 16: . CRITERION 16 - CONTAINMENT DESIGN. "--AN ESSENTIALLY LEAK-TIGHT BARRIER AGAINST THE UNCONTROLLED RELEASE OF RADI0 ACTIVITY TO THE ENVIRONMENT AND TO ASSURE THAT THE CONTAINMENT DESIGN CONDITIONS IMPORTANT TO SAFETY ARE NOT EXCEEDED FOR AS LONG AS POSTULATED ACCIDENT CONDITIONS REQUIRE." i l - 9 9
' 4 GDC 50: ,
)
CRITERION 50 - CONTAINMENT DESIGN BASIS. --AS REQUIRED BY SECTION 50.44, ENERGY FROM METAL-WATER AND OTHER CHEMICAL REACTIONS THAT MAY RESULT FROM DEGRADATION BUT NOT TOTAL FAILURE OF EMERGENCY CORE COOLING FUNCTIONING, (2) THE LIMITED EXPERIENCE AND EXPERIMENTAL DATA AVAILABLE FOR DEFINING ACCIDENT PHENOMENA AND CONTAINMENT RESPONSES, AND (3) THE CONSERVATISM OF THE CALCULATIONAL MODEL AND INPUT PARAMETERS." d i t I *.
~
i { O
- h. 4 -- . - -- .-- . .m. . , _ .. . . . . . . . . . . . . . . . . . ,
~ ...
. . 5 l
\
U.S. BOILING WATER REACTORS
\
I e 24 BWR 2/3/4 WITH MARK CONTAINMENT (ALL LICENSED) , . e 9 BWR 4/5 WITH MARK II CONTAINMENT (7 LICENSED) e 4 BWR 6 WITH MARK III CONTAINMENT (3 LICENSED) 0 i l i _ iO I vf e P
,-- .__-.._._._.....,_~.--..~.,,.-.--_._--..._._...m -
INSTITUTIONAL PROCESS e e CLOSURE OF SEVERE ACCIDENT ANALYSIS FOR CON
~ ',
- NO FURTHER ANALYSIS UNLESS EXCEPTION IS TAKEN o SPECTRUM OF OPTIONS
- RULEMAKING
- 50.5l4F LETTER FOLLOWED BY ORDER
- GENERIC LETTER FROM DIRECTOR NRR OR DIRECT -
e PROCESS CHARACTERISTICS BASED ON TECHNICAL WORK AVAILABLE, IDCOR, SOURCE PLANT SPECIFIC WORK, NUREG-1050, NUREG-1150
- OPEN TO PUBLIC FOR COMMENT AND PARTICIPATIO
\\
6 9 8 9 t
..e . e e e . .e .
7 A BWR - MARK I FOR REFERENCE i BEFORE ,, o CORE MELT FREQUENCY: 1x10-4/YR A FULL SPECTRUM OF SEQUENCES INCLUDING BLACK 0UTS e CONTAINMENT CAPABILITY: UNCERTAIN AND VARIABLE BUT ASSUME 1 OUT OF 2 CORE MELTS GIVES FAIRLY LARGE RELEASE AEIEE e CORE MELT FREQUENCY: 1x10-4kR / - IPE FOR FRONT END MAY REDUCE BUT NO CREDIT IS TAKEN HERE e CONTAINMENT CAPABILITY: SUBSTANTIAL ASSURANCE THAT CONTAINMENT WILL MITIGATE CONSEQUENCES, DEGREE VARIABLE FROM - PLANT TO PLANT BUT I OUT OF 50 CORE MELTS GIVING A FAIRLY LARGE RELEASE SHOULD BE REPRESENTATIVE E
'~
i
-, 1. ___ _ _ _ _ _ _ _ _ _
. ." 8 HYDROGEN CONTROL PROPOSED REQUIREMENTS 5
e CHANGE TECH. SPEC. AT END OF OPERATION FROM 24-HOUR ALLOWANCETO12-H0VRALLOWANCEOFNON-INERTEDONsRATIONAl REDUCED POWER e PERMIT 12-HOUR PERIOD AT REDUCED POWER WITHIN THE OPERATING CYCLE TO SEARCH FOR UNIDENTIFIED LEAKAGE RATIONALE e DEINERTING TYPICALLY TAKES 4-8 HOURS e LEAKAGE INSPECTION AND MINOR REPAIR CAN BE REASONABLY ACHIEVED IN 4-8 HOURS e REDUCED POWER (36 33%) SUBSTANTIALLY~ REDUCES SHORT-LIVED FISSION PRODUCT INVENTORY AND DYNAMICS OF POSSIBLE ACCIDENTS O 6 p... . . . -. ... . .... . _ ,_. .. . . . . . . - .
.. 9 DRYWELL SPRAY PROPOSED REQUIREMENTS e REDUCE DESIGN SPRAY RATE (CHANGE N0ZZLES) TO ABOUT 10% OF PRESENT VALUE e PROVIDE AC-POWERED BACKUP WATER SUPPLY FOR SPRAY AND AC-INDEPENDENT WATER SUPPLY, AVAILABILITY BY REMOTE MANUAL OPERATION OR BY SIMPLE RELIABLE PROCEDURE DESIRABLE ,
e MAKE ALTERNATE WATER SOURCES AVAILABLE TO COOL CORE DIRECTLY e 90/10 MODE OF RHR OPERATION RATIONALE h
.' s WATER SUPPLIES AND EQUIPMENT ARE ALRE'ADY AVAILABLE FOR LOWER FLOWS e LOWER. FLOWS PROVIDE ALL BENEFITS EXCEPT LOWsd T DECAY HEAT REMOVAL AND DO NOT RAPIDLY FLOOD CONTAINMENT e ASSURED DRYWELL SPRAY SUBSTANTIALLY REDUCES PROBABILITY AND SIGNIFICANCE OF DRYWELL FAILURE OR SUPPRESSION POOL BYPASS 7,...__......_....... ; , .
. }. - 10 PRESSURE CONTROL PROPOSED REQUIREMENTS ,,,
e RELIABLE CAPABILITY TO VENT WETWELL AT EPG PRES,SURE LEVEL WITH OR WITHOUT AC POWER. FOR VENTING WITHOUT AC POWER MANUAL PROCEDURE IN ADVANCE MAY BE USED IF NITROGEN PURGE IS AVAILABLE e VENT OF 18-INCH DIAMETER OR GREATER DESIRABLE e ABILITY TO VENT SLOWER SEQUENCES THROUGH STANDBY GAS TREATMENT SYSTEM , s BURST RESISTANCE DUCTING IN REACTOR BUILDING TO MINIM 12E COMPLICATIONS
~
RATIONALE e RELIABLE VENTING PREVENTS UNCONTROLLED OVERPRESSURE FAILURE WHICH'CAN CAUSE CORE MELT e VENTING WITH DRYWELL SPRAY GIVES GREAT ASSURANCE OF RELEASE - MITIGATION l l l
. _ = __
0 , 11 a .
~~
~~
COREDEBRIS ~ PROPOSED REQUIREMENTS ,
. )
e ASSURE RETENTION OF WATER AT LEAST 3 FEET DEEP IN TORUS ROOM IF TORUS LEAKS ENTIRE CONTENTS DESTRABLE e CONCRETE CURBS OR OTHER BARRIERS WHICH WOULD RETARD DEBRIS ATTACK OF DRYWELL SHELL - e AVOID LOSS OF RECOVERY SYSTEMS FROM WETTING BY TORUS ROOM WATER RATIONALE '. e DRYWELL FAILURE BY DEBRIS ATTACK IS MADE LESS LIKELY AND LESS SIGNIFICANT BY DRYWELL SPRAY AND VENTING e RETENTION OF TORUS WATER ENSURES DEBRIS QUENCHING AND SHOULD FACILITATE ACCIDENT RECOVERY W g., ;. . . .. . . . _ , . _
'. I-CHRONOLOGY e JUNE 16, 1986: MEETING WITH BWROG/IDCOR PROPOSED A GENERIC LETTER, PRESCRIPTIVE SOLUTION, BY BACKFIT JUNE 30, 1986: VERMONT YANKEE COMMITS TO GOV. KUNIN TO DO A
)
e - SPECIAL 60-DAY CONTAINMENT STUDY I e JULY 25, 1986: BOSTON EDISON COMPANY BOARD DECIDES TO FIX PILGRIM CONTAINMENT e AUGUST 19 1986: BWROG EXECUTIVES VOTE TO FUND AND CONTINUE DIALOGUEdNTHISWITHNRC,CONTACTNUMARCABOUTBWRVS.PWR e SEPTEMBER 11, 1986: MEETING WITH BWROG TO COMPARE BACKFIT NOTES AND STRAWMAN GENERIC REQUIREMENTS e SEPTEMBER 11, 1986: MEETING WITH VERMONT YANKEE TO REVIEW CONTAINMENT STUDY e SEPTEMBER 23, 1986: NRC/IDCOR MEETING ON BWR/ MARK 1 ANALYSES hhRF0 kC t0 kUShhRhEkSERRYW0kSHbREhbSANDBWR CONTAINMENTGENkRfCAPPROACH e SEPTEMBER 24, 1986: ACRS SUBCOMMITTEE ON C DISCUSS BWR/ MARK I ANALYSES AND SEVERE ENT PROGRAM
'e NOVEMBER 19, 1986: 'CRGR REVIEW OF DRAFT GENERIC t m ER ON BWR CONTAINMENT R EQUIREMENTS (TO BE PUBLISHED FOR COMMENT) e DECEMBER 17, 1986: ISSUE DRAFT GENERIC LETTER ON BWR CONTAINMENT REQUIREMENTS FOR PUBLIC COMMENT e APRIL 1987: ISSUE FINAL GENERIC LETTER ON BWR. CONTAINMENT REQUIREMENTS O
P h I***"'*'*** * * * ' ' ' * * * ' ' * " ' ' * * * * * * * * * * ' * * * * ' ' ' ' ' * *
- _ _ - - - - - - - - --}}