AECM-81-406, Forwards Addl Updated Info Re SER,NUREG-0831,per NRC Request
| ML20031F853 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 10/15/1981 |
| From: | Dale L MISSISSIPPI POWER & LIGHT CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0831, RTR-NUREG-831 AECM-81-406, NUDOCS 8110200483 | |
| Download: ML20031F853 (5) | |
Text
.
].
MISSISSIPPI POWER & LIGHT COMPANY Helping Build Alississippi EulMdhMiddB October 15 s
ble,'T.
S
B
/
U. S. Nuclear Regulatory Commission
'A-Ji
- /p Office of Nuclear Reactor Regulation 2
OcIl S ggJr -
7 E!
Washington, D. C. 20555 8;
- Ues, coy'83y n
~
Attention:
Mr. Harold R.
Denton, Director
\\g
Dear Mr. Denton:
v1 SU BJECT: Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416 and 50-417 File 0260/0862 Transmittal of Responses to NRC 53R Concerns AECM-81/406 In response to your request for additional information, Mississippi Power &
Light Company is submitting the enclosed miscellaneous materials updating in-formation pertaining to the Grand Gulf Nuclear Station Safety Evaluation Report (NUREC-0831).
If you have any questions or require further information, please contact this office.
Yours truly, bohl
)
L. :. Dale Manager of Nuclear Services JHS/JGC/JDR:mb Attachments:
1.
Discussion of the Stress Analysis of Members in the Auxiliary Building 2.
Clarification of Frequencies in the Response to New Madrid Fault Extension cc:
Mr. N. L. Stampley Mr. R.
B. McGehee Mr. T. B. Conner Mr. G. B. Taylor D
Mr. Victor Stello, Jr., Director h05,)f Of fice of Inspection & Enforcement U. S. Nuclear Regulatory Commission I ['
Washington, D. C. 20555 "110200483 811015 PDR ADDCK 05000416 E
PDR Member Middle South Utilities System
Attachnent 1 to AECM-81/406 CONCERN:
Stress Analysis of Members in the Auxiliary Butiding RESPONSE: Attached is a technical justification for the selection of one girder, an interior wall, and three steel bea.ns and a justification for the equation used to perform the stress analysis of these members in the auxiliary building.
l
(
Each structural member in the auxiliary building is designed to function for the load factor equations of FSAR subsection 3.8.6.
A comparison of the load combinations used by Grand Gulf and those contained in the SRP is shown in Tables 3. 8-35 and 3. 8-36.
Each SRP equation is compared to the corresponding Grand Gulf equation on a case basis and the degree of conservatism of the Grand Gulf equation with respect to the corresponding SRP equation is noted. Table 3.8-35 reveals that Grand Gulf equation (2) is less conservative than SRP equations (2a) and (2b) for,oncrete structures. Table 3.8-36 reveals that Grand Gulf equation (2) is less conservative than SRP equatinn (2) for steel structures. Consequently, FSAR Table 3.8-37 (for concrete structures) and Tables 3.8-38 through 3.8-40 (for steel structures) were generated to determine the degree of conservatism of the Grand Gulf design for those cases identified in Tables 3.8-35 and 3.8-36 where the Grand Gulf criteria was less conservative than the SRP criteria. Since FSAR Tables 3.8-37 through 3.8-40 reveal that the Grand Gulf design is conservative where the SRP criteria bounds the Grand Gulf criteria. the Grand Gulf design is conservative with respect to the SRP criteria for the auxiliary building.
The concrete interior wall analyzed in Table 3.8-37 is a representative, critical, highly stressed structural element in the auxiliary building which must withatand a range of loadings including earthquake, compartment pressure and pipe anchor loads. The structural integrity of this element is critical to the functional design of the auxiliary building.
Similarly, the beams and girder analyzed in Tables 3.8-38 through 3.8-40 are representative, critically loaded and highly stressed structural elements which must withstand pipe anchor, earthquake and safety-related equipment loads. These members are critical to the functional design of the au:iliary building since failure of any of these elements would result in partial collapse of the floor. These members were chosen based upon a review of the most highly stressed structural elements in the auxiliary building.
m
. to AECM-81/406 CONCERN:
Clarify Response to the New Madrid Fault Extension. Frequencies are shown in Table 3.7-11 below 2 Hz.
RESPONSE: The frequencies listed in lable 3.7-11 below 2 Hz are 1.64 Hz for the East-West direction of the containment building (flooded) seismic response and 0.19 Hz for the Horizontal Standby Service Water Cooling Tower (SSWCT) Basin seismic response.
For the containment building frequency of 1.64 Hz, this mode contri-butes only a small portion of the total containment response for a fully flooded containment condition (which operationally will not happen until a LOCA).
For the SSWCT Basin frequency of 0.19 Hz, this mode is a water sloshing mode and the change in design spectra below 2 Hz will not significantly affect this response. Table 3.7-11 is attached and has been modif
- to reflect this effect. Also, Figure 3.7-68a shows primary cont, snt modes below 2 Hz.
This is because the first containment mode at 0.23 Hz is the upper pool water sloshing mode. This mode does not contribute significantly to total containment response and was not included in Table 3.7-11.
Figure 3.7-68d does include the 0.19 Hz water sloshing modal f requency also contained in Table 3. 7-11.
l l
l i
l
.. p
SIGNIFICANT NATURAL FREQUENCIES FOR CATEGORY I STRUCTURES Significant Natural Frequencies Structures Direction (cps) 2.53 3.08 5.38 6.17 6.94 (Operating condiilon)
E-W 7.38 8.82 10.13 16.03 18.41 Containment building 24.21 25.74 29.36 29.75 30.3 N-S 2.53 3.08 5.37 6.17 6.94 7.40 8.82 10.13 16.26 18.64 23.75 25.01 29.36 29 67 30.18 Vertical 5.08 8.99 15.59 23.31 28.85 31.52 43.27 (Flooded to El. 208. 8)
E-W 1.64 2.07 3.41 4.69 5.56 Containment 6.33 7.10 8.87 9.84 13.97 building 14.81 16.80 19.22 20.33 23.4 Vertical 4.2 8.96.
15.48 20.29 27.03 31.52 Auxiliary building E-W 4.05 8.69 12.25 17.20 26.05 33.02 N-S
- 3. 7 8.91 14.47 18.34 25.58 35.65 Vertical 6.09 25.5 39.2 Control building E-W 3.65 9.48 18.01 22.85 36.1 N-S 4.18 9.78 17.15 24.75 37.8 Vertical 6.82 27.06 Diesel generator N-S 5.29 8.46 31.62 building E-W 5.38 10.35 38.41 Vertical 7.67 69.57 Standby service Horizontal 0.19
- 4.86 11.4 19.99 l 51 kater cooling 22.29 35.97 tower and rakeup basin Vertical 7.22 33.4 51
- Water Sloshing Frequency Miendment 51