ML20108D293
| ML20108D293 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 03/06/1985 |
| From: | Jens W DETROIT EDISON CO. |
| To: | Youngblood B Office of Nuclear Reactor Regulation |
| References | |
| NE-85-0344, NE-85-344, NUDOCS 8503080317 | |
| Download: ML20108D293 (3) | |
Text
.
4' Wayne H. Jens
+
Vice President
- Nuclear Operatens Fermb2 6400 North Dxie Highway
% Q y
- y "4,7 '"'8'8' March 6, 1985
.c NE-85-0344 Director of Nuclear. Reactor Regulation Attention:
'Mr. B. J. Youngblood,. Chief Licensing Branch'No. 1
. Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.
.20555
Dear Mr. Youngblood:
References:
1)
Fermi 2 NRC Docket No. 50-341 2)
Detroit Edison letter to NRC,
" Purge Valves - Additional Information",
EF2-72041, dated January 10, 1985.
3)
NRC to Detroit Edison letter, " Fermi-2 Containment Purge and Vent Valve Operability", dated March 1, 1985.
4)
Detroit Edison letter to.NRC,
" Purge Valve Operability",
EF2-72272, dated October 11, 1984.
4
Subject:
Purge Valves - Followup Information
-Subsequent to NRC. review of Reference 2, Mr.
R. Wright (NRR-EQB) requested-additional information on the containment purge and vent valves.
The request was documented in Reference 3.
The discussion below addresses the specific requests of Reference 3.-
The bracket material for the 10-inch Jamesbury valves is
,i ductile ~ iron, Grade 604010.
The bracket material for the 24-inch Jamesbury' valves is carbon steel, SA-36.
l.
Based on review of Attachment 2.(Table 2) of Reference 4, the existing bolts for the 10-inch Jamesbury valves are not overstressed..An allowable-shear stress.of 42,000 psi for g
bolts made of SA-193 B7 envelopes the maximum calculated stress values for the subject 10-inch valve bolts.
In addition, based on ' the removal of an overconservatism in the analysis in the same Attachment 2, the existing bolts for the'24-inch Jamesbury valves are not overstressed.
A 1
0
\\
r Mr. B. J. Youngblood March 6, 1985 NE-85-0344 Page 2 The maximum total shear stress for the 24-inch valve bracket bolts was previously calculated to be 44,000 psi (refer to Table 2 of Attachment 2).
This value was calculated by adding the maximum shear stress for. seismic to the maximum shear stress for torque and multiplying this sum by 2.06,-
the stress' amplification factor.
Referring to page 4 of 27 of Supplemental Calculation No. 1
. tx) Attachment 2, the previous calculation was:
't max (seismic) = 15,120 pai QTmax (torque)
'6,270 psi
=
21,390 psi
?rmax (total) = 21,390 psi x 2.06 OL 44,000 psi.
The latter value (44,000 psi) was the calculated overstressed condition in consideration of an allowable design stress of 42,000 psi (105,000 psi x 0.4) for the SA-193 ' B7 bolts.
As explained on pages 5 and 6 of Attachment 2, the stress amplification factor (2.06) applies to dynamic torque,.not the seismic stress.
Therefore, the more correct application of the 2.06 value is:
T max (torque) = 6,270 psi 6,270 psi x 2.06 ot 12,900 psi 1Tmax (torque) x 2.06 s 12,900 psi 1fmax (seismic)
= 15,120 psi Tmax (total)
= 28,020 psi Therefore, by comparison to 42,000 psi,.the existing bracket bolts for the 24-inch valves are acceptable.
e Mr. B. J. Youngblood March 6, 1985 NE-85-0344 Page 3 Please direct any questions to Mr. O. K. Earle at (313) 586-4211..
Sincerely,
/
cc:
Mr.
P. M. Byron l
Mr. M.
D.
Lynch Mr.
R. J. Wright USNRC Document Control Desk Washington, D.C..
20555