ML19323H454
| ML19323H454 | |
| Person / Time | |
|---|---|
| Site: | Vallecitos File:GEH Hitachi icon.png |
| Issue date: | 11/14/1979 |
| From: | Jeffrey Reed JACK R. BENJAMIN & ASSOCIATES, INC. |
| To: | |
| Shared Package | |
| ML19323H451 | List: |
| References | |
| ACRS-1691, NUDOCS 8006130014 | |
| Download: ML19323H454 (19) | |
Text
J
[
g PROBABILITY ANALYSIS OF SURFACE RUPTURE OFFCET BENEATH CENERAL ELECTRIC TEST REACTOR REACTOR BUILDING by John W.
Reed Jack R. Benjamin and Associates, Inc.
ACRS Subcommittea Meeting General Electric Test Reacter November 14, 1979 Jack R. Bonjomin & Associates. Inc.
3 Consulting Engineers I
Court House Picto Buiteng. Sude 205 260 Stecon Ave. No Alto. Coidorno 94306 80061s.00ft/
PURPOSE OF PROBABILISTIC ANALYSIS 1.
To detern$ine the probability of occurrence of a future surface rupture offset of any size greater than zero beneath the Reactor Building foundation 2.
Then to determine whether the probability of occurrence is sufficiently low so that surface rupture offset should not be considered as a design basis event Jock R. Benjamin & Associates,Inc.
Consulting Engineers l
l f
a PROBABILITY ACCEPTANCE CRITERlON
.... a conservative calculation showing that the probability of occurrence of potential exposures in excess of the 10CFR Part 100 guidelines is approxi-mately 10-6 per year is acceptable if, when combined with reasonable qualitative arguments, the realistic probability can be shown to be lower."
USNRC Standard Review Plan Section 2.2.3 suit n Engin r o
s RESULTS AND CONCLUSION OF ANALYSIS RESULTS Calculated probability of occurrence of a future e
surface rupture offset of any size greater than zero beneath the Reactor Building foundation complies with the criterion Probabilistic analysis is conservative e
CONCLUSION Surface rupture offset should not be considered as a design basis event l
e I
Jock R. Benjamin 8 Associates,Inc.
9 Consulting Engineers
l l
l l
OUTLIN.E OF PRESENTATION OF PROBABILISTIC ANALYSIS Simplified approach Confidence level probability analysis e
Detailed model analysis e
l
=m=~2
LOCATION OF SHEARS IN RELATION TO GETR
\\
\\s N s'\\
\\
i
\\
B-1 B-3
/
\\
- T B-2 & side trenches s
SCALE.
o 20,00 feet 0
e
.I
.,__..m
. ~-
-.- e
CROSS-SECTION OF GETR SITE i
t 2Y2' l
1320*
l Trench B-1
^
Trench B-2 f
'i
' ~
)
REACTOR BUILDING 72 sh. rs-2 i
n hw I
s-SCALE: Hockessemi = Vertical
,5 {
O 200 400 SOO 900 1000 e
e i
i e
a mo J3 feet 55 3.,
5 i
E 2
8 l
t e e
i 4
OBSERVED OFFSET DATA
~
Maximum Offset During
?
Time Period (ft)
Time Period (Before Present in Years)
Shear B-2 Shear B-1/B-3 0-8,000 to 15,000 0
0 8,000 to 15,000 - 17,000 to 20,000 3
2 17,000 to 20,000 - 70,000 to 125,000 5
10 gg 70,000 to 125,000 - 128,000 to 195,000 or greater 80+
40+
p 5=
= 8 II 5g 8*
ar a
2 if
BASIC PROBABILITY PARAMETERS Annual probability of occurrence of an offset beneath' Reactor Building foundation, P:
P=PxP 3
2 Where:-
P
= annual probability that an offset will occur 3
between shears B-2 and B-1/B-3 P2 = probability that an offset will occur beneath the Reactor Building foundation, given that an offset occurs between the shears e
===-J
_ l
SIMPLIFIED APPROACH t = 128,000 years t = 195,000 years P
a 1/128,000 P
a 1/195,000 j
3 P
a 72/1320 P
a 72 /1320 2
2 P=P 3xP2 P = 1/128,000 x 72/1320 l' = 1/195,000 x 72/1320 5"
- f P = 4.3 x 10-7 P = 2.8 x 10-7 g
Il n
!.I it
CONFIDENCE LEVEL PROBABILITY ANALYSIS P = - En (1-C)/t 3
Where:
C = Confidence level probability Number of years without an offset t
=
between the shears P2 = (2+b)/(L-b)
Where:
2
= Width of Reactor Building L = Distance between two existing shears b = Width of offset at ground surface P=P3xP2 I
Jack R. Benjamin & Associates,Inc.
Consulting Engineers i
PROBABILITY OF OFFSET OCCURRING BENEATH REACTOR BUILDING FO.UNDATION f
Confidence Level No. of yrs. without an event Probability t = 128,000 yrs t = 195,000 yrs 0.95 1.4 x 10-6 8.9 x 10-7 0.90 1.0 x 10-6 6.8 x 10-7 g
in kI.
0.50 3.1 x 10-7 2.1 x 10-7
$3-
\\
- t k
l I
k l
DETAILED MODEL ANALYSIS 3'. -
P =pAe4 3
Where:
A = Mean time rate of occurrence of offsets
= Probability that an offset will occur between the two shears given that an offset occurs P = (2+b)/(L-b) 2 Where the parameters are the same as the confidence level probability analysis P=PxP 3
2 I
Jock R. Benjamin & Associales,Inc.
Consulting Engineers D
METHOD FOR OBTAINING PROBABILITY DENSITY FUNCTION FOR A AND c Oly.f. t c t-J;,*.t.T p(A,6) = @ L(A.cidata) p'(h.e) i
(
Where:
$ = normalizing constant p'(X,$) = prior probability density function 4 (At;)"i e At; Il L(A.c Idata) =
n;I i= 1 1; = time period (years) n; = number of events in time period t; D(A, ) = t"+ I A" e-" (n+ 1) (1-Q)n for 0 < $ < 1 A>0 nl Where:
4 t= It i i= 1 4
n = I n; i= 1 I
Jock R. Ber.jamin & Associates,Inc.
Consulting Engineers D
\\
l ESTIMATED VALUES FOR PROBABILITY P3 Weighted estimate 1
=
E, = [ [
Ae'A p(A, ) dad $
n+2 ft i n+1 1
"It+1j n+2 t
1 1<
Confidence limits 4
P = $Ae h
3 Region 1--
iy
> A I
Jack R. Benjamin & Associates,Inc.
E Consulting Engineers
PROBABILITIES OF OFFSET BENEATH REACTOR BUILDING FOUNDATION Detailed Model' Confidence Level Prob. Analysis Analysis Basis t = 128.000 yrs.
t = 195,000 yrs.
t = 128,000 yrs.
t = 195.000 yrs.
Weighted estimate 4.5 x 10'7 3.0 x 10 7 NA NA 0.95 Confidence level-1.3 x 10-6 8.4 x 10 7 1.4 x 10-6 8.9 x 10 7 0.90 Confidence level 1.0 x 10 6 6.7 x 10 7 1.0 x 10-s 6.8 x 10 7 0.50 Confidence level 2.9 x 10 7 1.9 x 10'7 3.1 x 10 7 2.1 x 10 7
- Based on n = 15 1
I Jock R. Benjamin & Associoles,Inc.
D Consulting Engineers
CONFIDENCE LEVELS FOR OFFSET BENEATH REACTOR BUILDING FOUNDATION FOR 10-8 CRITERION PROBABILITY VALUE I
Detailed Model*
Confidence Level Prob. Analysis t = 128,000 yrs t = 195,000 yrs t = 128,000 yrs t = 195,000 yrs 0.91 0.97 0.89 0.96
- Based on n = 15 Jock R. Benlomin & Associates,Inc.
Consulting Engineers l
.-l EVALUATION OF CONSERVATISM Probability of potential consequences are at.least one order of magnitude lower Offsets can occur outside of area between the two shears e
Conclusion is based on t = 128,000 years. An average value between 128,000 years and 195,000 years is more appropriate.
Furthermore, the age of unfaulted soil material is probably older than 195,000 years "W
Prior distribution for A and $ was conservatively assumed EI in Detailed Model II Two-dimensional geometric model is conservative
((y 5
E i
b
SUMMARY
AND CONCLUSION 6
Weighted estimate probability value is less than 10 e
i 0.90 Confidence level value is essentially equal to 10-6
=
Probabilistic analysis is conservative e
Analysis and results comply with criterion e
Hence j
gg E.%
Surface rupture offset of any size should not be considered
((
e 4j.
as a design basis event lr Rg
_I li m
,-.ww
. g