ML19254B438
| ML19254B438 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 08/31/1979 |
| From: | Burstein S WISCONSIN ELECTRIC POWER CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 7909270808 | |
| Download: ML19254B438 (3) | |
Text
F/ b WISCONSIN Elecinc mia coum 231 W. MICHIGAN, P.O. BOX 2046. MILWAUKEE, WI 53201 August 31, 1979 Mr. J. G. Keppler, Director Office of Inspection and Enforcement Region III U. S. NUCLEAR REGULATORY COMMISSION 799 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
DOCKET NOS. 50-266 AND 50-301 IE BULLETIN 79-02 P0 INT BEACH NUCLEAR PLANT, UNITS 1 AND 2 Our initial response of July 6,1979 to IE Bulletin 79-02 referenced the seismic risk analysis contained in Appendix 2K of the Haven Nuclear Plant Site Addendum. This analysis estimated an average recurrence interval for an Operating Basis Earthquake (0BE) at the Haven site, approximately 30 miles south of Point Beach, of 1595 years. This would indicate a probability of an OBE at Point Beach of only about 6 x 10-4 per year.
During a review of these calculations, we have detemined that errors existed in two of three equations used for attenuation of ground motion from the earthquake apicenter to the Haven site. These errors resulted in over-estimation of the average OBE recurrence interval.
In addition to these errors, refir.ements in seismic risk calculations have been developed since the original analysis was perfonned. The calculations have been redone using ~re/ised equations representing the present state-of-the-art and indicate an average recurrence interval of 419 years or a probability of about 2 x 10-3 per compared to the original estimates of 1595 years and 6 x 10-4 per year. year The results of the n! vised seismic risk calculations are enclosed as Table 1 and should be substituted for Table 2K-3 in Appendix 4 of our July response.
The revised recurrence interval, while lower than original estimates, does not alter the conclusion in our response that continued plant operation is acceptable while the anchor bolt and pipe support plate verification program is being completed.
Very truly yours.
!b A
Sol Burstein F.
c Jtive Vice President
?4 212 Enclosures h \\9b 7909270
TABLE 1
. ANALYSIS OF EARTHQUAKE INTENSITY AT SITE Annuni Risk at the Site of Exceeding Intensity Attenuation Rate Hono IL 1.4.
(km)
VI VIf VIII Law
-4 Brazee 0.001 4
7.0 0.845 40
.6.75 x 10 0.0 0.0
-3
-5 0.001 4
7.5 0.845 40 1.18 x 10 7.10 x 10 0.0
-3
-4 0.001 4
8.0 0.845 40 1.77 x 10 2.09 x 10 0.0
-3 0.001 6
7.0 0.247 40 2.78 x 10 0.0 0.0 0.001 6
7.5 0.247 40 4.11 x 10-3 2.47 x 10 0.0
-4
-3
-4 0.001 6
8.0 0.247 40 5.o7 x 10 6.70 x 10 0.0
-4
-5
-6 Gupta &
0.536 4
7.0 0.845 23 5.78 x 10 6.78 x 10 1.63 x 10 Nuttli
-4
-4
-6 0.536 4
7.5 0.845.
23 7.81 x 10 1.22 x 10 7.74 x 10
-3
-4
-5 0.536 4
8.0 0.845 23 1.03 x 10 1.79 x 10 2.10 x 10
-3
-4
-0 0.536 6
7.0 0.247 23 2.39 x 10 2.80 x 10 6.73 x 10
-3
-4
-5 0.536 6
7.5 0.247 23 2.72 x 10 4.25 x 10 2.70 x 10
-4
-5 0.536 6
8.0 0.247 23 3 29 x 10-3 5.74 x 10 6.73 x 10
-4
-6 Howell &
0.64 4
7.0 0.845 25.5 8.38 x 10 9.98 x 10-5 4.63 x 10 8 *"It*
-3
-4 1.41 x 10-5 0.64 4
7.5 0.845 25 5 1.16 x 10 1.72 x 10
-3
-4
-5 0 64 4
8.0 0.845 25.5 1.53 x 10 2.60 x 10 3.09 x 10
-3 4.12 x 10-4 1.91 x 10-5 0.64 6
7.0 0.247 25.5 3.46 x 10
-3
-4
-5 0.64 6
7.5 0.247 25.5 4.05 x 10 5.98 x 10 4.93 x 10
-3
-4
-5 0.64 6
8.0 0.247 25 5 4.91 x 10 g,33 x 10 9.91 x 10 o Risk Per Year I
Average 2.38 x 10 2.90 x 10-4 1.94 x 10-5
-3
-4
-5 Maximum 5.67 x 10 8.33 x 10 9.91 x 10 N
Mininum 5.78 x lo-4 0.0 0.0 Return Period _ (Years)
Average 419 3448 51,546 Maximum 1730 Minimum 176' 1200 10,091 m.+ 1 nc 9
r.-
'6
\\
s TABLE 1 (cont'd)
ANALYSIS OF EARTHQUAKE INTDISITY AT SITE Attenuation Lavo Brazee I = 3.387 + I, - 0.894 InR - 0.00289R Gupta &
I = 3.7 + I, - 1.173 inR - 0.0011R Nuttli Howell &
I = 3.278 + I,- 0.989 InR - 0.0029R Shultz Definitions P
is standard deviation I g, is lower bound intensity of source area C) -
A I.
is upper bound intensity of source area
-c.
Rate is annual rate of os mrence of earthquake 2 I o
[
Rone is radius from epicenter for which there is no attenuation Sheet 2 of 2
.