ML19220B281
| ML19220B281 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/04/1975 |
| From: | Grimes B Office of Nuclear Reactor Regulation |
| To: | Regan W Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7904250585 | |
| Download: ML19220B281 (10) | |
Text
...
b 0':.
W Regan, Ermch Chief Environmental Projecta 4 E5ALLSTIC ACCIZE:tT ASSESSMENT - THREE MILE ISLAND UNIT 2 FLA C NAME: Three :lile Island Nuclear Station, Unit 2 I.ICENSI:iC 5 AdE: OL DOCTET NCCE1: 50.-320 MILESTONE NUDER: 33.31 RESPONSIBLE BRANG: ZP-4; LVR 2-2 REQUESTED COMPLETION DATE: Septenber 23, 1975 DESCRII* ION OF R2SPCUSZ: Realistic Accident Assessnent REVIEW STATUS: AAB Input Coczplete Enclosed la the realistic accident assessment for the Three Mile Island Nuclear Station, Unit 2 Draf t Environmental Statement prepared by E. Adensam, of the Accident Analysis Branch. In addition to occm edi-torial changes, the man-rem estinates have been changed from those published earlier to reflect the projected 2010 population presented in the apolicant's FSAR, Figures 2.1-8 and 2.1-13.
This does not altar any of our conclusions.
Brian K. Grimes, Chief Accident Analysis Branch Division of Technien1 Review Office of Nuclear Reacter Regulation Encicsure:
As. stated cc: w/o enclosure R. 3oyd W. Mcdonald DISTRIBUTION:
J. Panzaralla
- Central Files NRR/ Reading w/suclosure AAB/ Reading S. Harauer R. Hai - an 79042505E6 7 Mo r*
D. Muller
- 3. Grfmes K. Knell
' p'
- 2. Siln:
/
//
J' N0ffi8
...AA3/SS/g/vg.,,, 5 p-o...c s.-
}.~ 1,.,<.b O. Ferrell._._
E.Ad'gfmam..
Ejf izes
'/l ev=-a"'*
E.-Adensam W-
-/--
..11/_._ 75. _
11/Y._/75_
o * *=
- Forse AZC,314 (Rev. 9-3 3) AZCM Q240 TT u. s. aovsanusm? pesamme oprices te7e.eae.t se
~.
. L
^1.
Environ =en:a1 L: pact of Postulated Accidents A high degree of protection agains t the occurrence of pos tulated Station. tait 2 accidents 1.2 the Three Mile Island :Tuclearp.a proviaed through correct design, ratufa: ure, and operation, and the quality assurance prog c used to es:2blish tha necessary high integrity of the reactor system, as will be considered' in the Cc==ission's Safery Evaluation.
Devia-tions that ay occur are handled by protective systers to place and hold the plan in a safe conditica.
- otuithstandin; thia, the cca-servative postulate is =ade that sericus cccidents sight e. cur, even though they cay be extremely unlikely; and engineered safe t y features
,y are incts=d *o citigate :he consequences of those postulated events which are judged credible.
The prcbability of occurrence of accidents and the spectrum of their ccusequancas :o be censidered fr:: an envir:nnental ef fects standpcin have been anal :2d usin; best esti=stes of probabilities and realistic f
fission pr:iu:: release and transport assuaptions.
For site evalua:ica in the Cc- 'ssion's safe:y r2 view, extremely censervative assu=ptions are used for the purpose of cocparing calculated doses resulting frca a hypothetical release of fission products frc= the fuel cgainst :he 10 CFR Par: 100 siting guidelines. F.ealistically computed doses that uculd bc ::::ived by the popula:icn and envircament frem the cecid ents vhich are. s:ula:ed vculd be cignifican:1y less than thos a to be precented in th: 5:f0:7 E; lue:ica.
'j4 ~j ['S
The Cecaissica issued guidance to applicanta ca Septa::ber 1,1971, requiring :.*.e censideratica of a spec:run of accidents vich assu=ptions as realistic as the sta:e of knculedge per=its. The applicant's response was cen:ai ed in the Three Mile Island Nuclear station, Unit 1 and Unit 2 Environ = ental Report Operating License State, dated Dece=ber 10,1971.
The applican:'s reper: has been evaluated, using the standard acciden:
assu=ptions and guidance issued as a proposed a=end=ect to Appendin D of 10 CF?. ?ir: 30 by the C:::ission en Dace:bar 1,1971.
Nine classes of postula:ad 1::idents and cccurrences ranging in se reritf frc tri712'_
to very serious sere identified by the Cc==ission.
In general, acciden:s in the hi;h potential consequence end of the spectru have a Icw c: cur-rence rate 2nd chose on the low potential consequence end have a higher occurrence rate. The exa=ples selected by tha applicant for these cases are aho n 1: Table I.
The exar.ples selec:aci are reasonably hc=ogeneous in terus of probability vi:hin each class.
Cae:21ssi:r es:i:2:as of tha dcsc which night be received by an assu_2:1 individual 3: 2 din; a: the site boundar/ in tha doun rind direction, using the assemp:icts in the proposed Annen to Appendi:t D, ara presented in Table II.
Estimates of the integrated exposure that night be delivered :o the population uithin 3C ciles et the site are also pre-sented.in Table II.
Tne nan-ren esti ::e war based on the projected population within 50 miles of the site for the year 2010.
e 74 200
e h
To rigorously es:ablish a realistic annual risk, the calculated doses in T2ble II would have :o be cui:1pli2d by esti= :cd probabili-ties. The events i= Classes 1 and 2 represent. oe:urrences which are anticipa-=d d"-ing plant operations; and their c nsequences, which, are terf s.all, are considered within the fraceuork of routine afflue::s frem the plant.
F2 cept for a li=ited anot.n of fuel failures end sone steam generator leakage, the events in Classes 3 :h ugh 3 are not anticipated duri ; pican oper tion; but events of this type cculd occur scretica durit; tha 40 year plant lif ati=e.
Accidents in Classes 6 and 7 and s=211 accidents in Class 8 ara of similar or lower prcbability than accidants in 9
^
Classes -3 through 3 but are still possible. The probability of occurrence of lar;e Class 3 accidents is very sesil. Therefore, when the consequences indicated in Table II are weighted by pro babili:ies, :he envirenzen:a1 risk is very low. The postulated occurren:es in Class o involve sequences o f successive f a.ilures
= ore severe :han chose r:quirad to be considered in the design bases of pro::::i:n systens and engineered safety features. Their consequenc2s : uld be severe.
However, :he probabili:y of : heir occurren:2 is judged se s=211 that their environ: ental risk is extre:ely 1:w.
Defense in. depth (nul:1,la physical barriers), qual-icy assurance for design, r.cnuf 2c:ure and Operatica, continued sur-veillance end :es:ing, cnd conservative desi;n ara cil applied to e
me.
O%
k
_4_
provide and =aintain a high degree of assurance that po:cntial accidents in this class are, 2nd will res in, sufficiently small in probability : hat the environ =en:a1 risk is extrece. y low.
The NRC is currently perfor=ing a study to assess = ore quantitatively these risks. The initial results of these efforts were made available e
for co==ent in draft form en August 20, 1974, This study is called the Reactor Safety Study and is an effort to develop realistic data on the probabilities and sequences of acciden:s in water-cceled pcuer reactora, in order to improve the quan:ificatica af availabla knculel;a related to nuclear reactor accidentsprobabilities. The Cc==1ssion organized a special group of abcut 50 specialists uader the directica i
~
of Professor Norman Rasmussen of MIT to conduct the study. The scope of the study has been discussed with EPA and described in correspondence with EPA which b,s been placed in the NRC Public Docu=ent Roem (letter, Doub tu Datinick, dated June 5,1973).
As with all new information developed uhich 1 ht have an effect en 3
the heal:h and saf ety of the public, the results of these studies will be =ade public and vill be asscssed on a tirely basis within tha Regulatory process on generic or specific bases as may be uarranted.
Table II indicates : hat the realistically estimated radiolo;ical consequences of the postulated accidents would result in exposures
- "Reacto r Safety
.edy - Eit Assessment of Accident Riaks in U. S.
Commercial Nuclee.c aza r t ants, Draf t," ' ASH-1400, Augua : 19 7 '..
u _a
)
of an assur.el ia..
.:21 a: :::e si:e becadary 'Aich are less :han or con: para 5'le. to :: 's-rhic:' 'cend re sul: f rer a ycar's e::pesure to che Maxir.un Pe r:..u a i'a t e Cencan:ra:icas C: C) ef 10 CTF. Part 20.
The table also src.. the estira: : in:2; rated sp.sure o f :he populat ten within 30 riles af the p12n: from ea:5 pos:uic.ted acciden:.
An: et~ these in-te;ra:cd cxposurcs t:culd be u.: scal'.ar than that frem naturally occur-ring radicactivity. ' sen censidered ' tith the probabilit.y of os:currence, the annual ; ::en:.ini radia:i. - e:-:pesure of the peculat ien ::..all the postulated acciden:s is an even smaller fraction of the
-'osure frc:t natural background radiation and, in fact, is well with' naturally accurrin:; variatiens in the natural back;rcund.
It is concluded fre:, the resul:s of the realistic anal / sis that :he a
envireneental risks due :: postulated radiclogical acciden:s are exceedingly 3:211 and.eed nc: be censidered further.
t P.
7tT03
. k a-e O
6-AM, L..t.
I
=. C S ~4 '6 '. '.". ' D '.". " T "
'..'~4 5 4.". D
- w* r * ' m. ?.=.'.s' C = 3 C ' A 'J.c i. C.'.~. T. C.'.'
"v '.;'
-1 w..
s.
w ww C '..".. s 4F u-
'_ O e. C. d. s d o. "..
rd,1 4_ C -.'.. ' s L *...m.
.* (' ~a )
1 2.,/.t.,.1 I.
_;,1,,.,. S yon a.
.v. *
.S=all '_cicases Cu tside Spill in Ss:ple "ce:i 2
. C O n, _,,.....,... -
3 Rac:cs te Sys::.-i 72ilure Inadvc::ent Release of '!aste cas
,,C..
,.1.s.
4-.
o.
..s....,
..a.
...,,_ _e
...,, c
=. <.. >...........s Sys tc 2 C/...s) 5
- s.* c. i.'.
u' '......., 3..'....m,-
0.. w c.'.~ )- C. m...' C v.. n...'.'.. '. '~ -;-
3,.,,.
o
^
.. o a nu' S c m~
~....* ~., '.'.c..'.-~.s
', '....*G
' e a T.*.
. o '.. e.". ".. 0 6
. "... _ '.. ~
- v.. O..... 1. s.,..2...
n.,,...........
- e.. r.
.._.,s...,
.. i.., A.
.. C 1 L,..
.r. O., C v. s.,, s. C,.
...e...
AuOC e.
6
... ~.. _ ' _ ' _. ~,
.s. m.v. s. n. 2 D. w~, o ' =. t. e 1_..:c, e..- _' ', c - n. - m. f..,. '.
-=.=.w.g-3 s
- 0..JJCCO CO. Ca 3..iS O 3.,.y JU 7
,..c i t... L.
1 ts..,2. $__J,.,
. '.r. C _4,J. G.,.
.n.,-,.
O.=
- L. C l et., S c_ J e*..
a.
s
.w y
3,,
1., C.s d 0 1 v.....c...n..
'v
- m. e, e,.' 0, s'..' '. '..'. -. o-t' e - -. ' \\' '.. -
a.
.,-..Cq.
.a Co
- e. e.._ n_7 s,.;
- 4..,.- n,, 4.,;..
f'. 3 _43
(",n g 3
...o r,,.,.1.... _e C.-...
.1.
.c... e......n
....w...
A n!*. l.y S iS ,. 'J T !
EC C.
'c.*i '..d r ' *
- 31 A C C id. c ?. C
.v..a.1.,,...,. C.
.n e..t.,, 4. C.,..
4_ s..o n..
9
( s,.'..*. * =.,,. -.
..,.22, LOeS C.: w CYe.i..,..
..s..
e
_4 s...
S,.
- e..,.
s
- s ws s...g--
C.... -......-.u.a T.,C c. < o.f
" _1 gs. L...' C.... '. '.
...C.# d.a...
me i
La. C w...,...
,.,.. s.
%.a ;.9..
..s w
$ t c.a..-,.
- ...r4...
- a.. p. '.u- ~ %
- p eg n,w_meyb
.w e. *
.%....g...s...ew.
...q
=
'%.,, I
,..e....
t..,,,.
c.. ; C,;....
Ag s g
..Q,=
y.%...
d.
o,
...f...
e
- s. lone b
k.
bI.
g*a
}
C.,.,. 6 t L1, _ f v
. m __
s TABLE II S~u." r.i o.v. C. R..'m' -c r o r.e.a r.
C s., a _.~_... u..2
-v 0,:,
0 a__...L. -.D
.4 Cw-7,,._ './
r v.i:
Esti=sted Fraction Es ti=ated Dese of 10 CF3. Part 20 to Popula:ica ia li=lt at site 50 mile radi::s 9
Class Even:
boundare /
r
=an-ren 1.0 Trivfal in:1dants 3/
3/
2.0 S=all relassas outside 3/
3/
CCntai" Snt 3.0 Raduas:e 5;s c7 failures 3.1
' Equip en laakage or =al-
~
fumetic:
0,073 11 3.2 Relaasa of uast e gas storage :22'c centents 0.29.
44
(
3.3 Release cf liquid waste storage cc::ents 0.003 0.52 4.0 Fission products to pri=ary N. A.
N. A.
systen (r2.)
-1'/
Tne dases - ' -"' ' ed as consequences of the postulated acciden:s are based on airbo ne ::ansper: of radicactive na:erials resulting in bo:h a direc: :ni :n inhala:ica dose, Our evaluati:n of the accident des e s assures tha: :h2 apolican:'s environ = ental :::it:Mn; propan and appropria:e addi:icnal tenitoring (uhich could be initiated subsaquent
- c a liquid release inciden: detected by in-plant =cnitoring) would detect the presence of radica::ivity in.the enrincncent in a tirely cancer such : hat recedial action could be
'-~' if necessm; to licit anposure frc: c ther potential pathways - --
-2/
Represents the calculated fraction of a whole body dos e of 500 =ren, er :he equivalca: dese :o an or;an.
M These. radionuclide releases are considered in developing the. gaseous and liquid source ter: presented in See:1on 3 and are included in dc.es in Section 5.
I k
c) I ' L -
(
.L L d
u e
~
8-
.7A - Con inued Anocc Esti=ated Fraction Es t -' ~ ^d n
4 oce of 10 CFR Part 20 to populstica limit at, ice in 50 mile Class Event bound 2r:. '
radius, min-rca 5.0 Fission products to pri=ary and sacrda 7 systens (ETR) 5.1 Fuel c ~ = > ' g d e f e::s a nd steaa ganarator laaks 2/
'3fJ 5.2 off-design :: nsian: tha:
induce feal failure above these expec:ad and ste:n genars::: 1eci 0.002 0.25 5.3 S:ca: genera::: tuba rupture 0.096 14 i
6.0 Refuelin; accidents 6.1 Fuel bundla drop 0.015 2.3 6.2 Heavy cbject drop onto fuel in core 0.26 40 7.0 Spent feal 'c2ndling acciden:
7.1 Fuaf assa bly d:cp in 0.01 1.4-
- a-7.2 Eea'r-obj ec: drop onto fuel rack Q.Q38 Ss8 7.3 Fuel :asi d::?
0.11 33
3.0 Accidan
ini:12:ica even:s considerad in design basis evaluation in the SAR 8.1 Loss-of-Coolant Acciden:s Scall 3reak Q.16 44 Large 3:ack 1.2 1100 e
9 O
O g
9
~
_g_
TA3LE II - Centinued Esti=ated Frac: ion Esti &!
P.,w of 10 CTR Pant 20 to populatica limit at, ita in 50 mile Class Event bounda--a.
radius, can-ren 8.l(a)
Break in instru an: line from N. A.
N. A.
prinary sys:en :ha: penetra:es tha con:a'- ent 3.2(a)
Rod 2j a::icn c0:122a: (EIR) 0.12 110 8.2(b)
Rod drop at:ident (;!.7)
N. A.
N. A.
8.3(a)
Star.nline b:caks (E P.'s outsida contain=en:)
S all 2:eak
< 0.001
< 0.1
- Larga 3 cak
< 0.001 0.14 8.3(b)
Stan: lina break (3'l2)
N. A.
N. A.
1 e
B 1
e e
e w ;L ry s y) 4 Lc