ML20101F232
| ML20101F232 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 06/18/1992 |
| From: | Zeringue O TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9206240343 | |
| Download: ML20101F232 (4) | |
Text
. _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _
1 4 w k
$ $$$IeveevA w !,.onoweBa m om em eer 4 wo O.J 1ko'Zenngue ece ncscent nws re"y openers JUN 1 8 1992
/
u.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
)
Docket Nos. 50-259 Tennessee Valley Authority
)
50-260 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) - HEATING, VENTILATION AND AIR i
CONDITIONING (HVAC) SEISMIC DESIGN CRITERIA - RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION
References:
1.
TVA letter dated November 15, 1991, Heating Ventilation and Air Conditioning (HVAC) Seismic Densign Criteria 2.
TVA letter dated May 6, 1992, Heating, Ventilation and Air Conditioning (HVAC) Scismic Design Criteria, Response to Request For Additional Information This letter provides clarification regarding revisions to BFNs Seismic Design Criteria for Class I HVAC duct and supports. This information is being submitted to address staff questions.
BFN submitted Seismic Design Criteria for ductwork aN. supports of Class I HVAC systems (BFN-50-C-7104 Revision 6) in reference 1 as a post restart TVA Nuclear Performance Plan cotamitment. TVA met with the staff on January 23, 1992, at NRC headquarters in Rockville, Maryland to support technical review of the criteria.
Subsequently, BFN and the staff technical eviewer(s) held several teleconferences to resolve emergent technical questions. As a result of the meeting and teleconferences mentioned above, TVA agreed to revise specific sections of the Class I HVAC seismic design criteria. Reference 2 identified the sections revised and provided a summary of the revisions. However, the staff requested that the specific revised sections be submitted for their review.
pg 9206240343 020618 PDR ADOCK 05000259 P
}
2 U.S. Nuclear Regulatory JUN 181992 The Enclosure to this letter identifies the staff questions / requests and provides the corresponding revised section(s) to the BFN-Class I HVAC Seismic Design Criteria. The revised criteria, BPN-50-C-7104, Revision 7, in it's entirety, is available for review at the TVA Rockville, Maryland office.
TVA considers that the information requested by NRC has been provided and requests the issuance of a supplemental Safety Evaluation Report.
There are no new commitments contained in this 1ctter.
If you have any questions, contact R. R. Baron, Manager of Site Licensing, at (205) 729-7566.
Sincerely,
/
t s'
O. J. Zeringue Enclosure cc:
(Enclosure)
URC Resident Inspector Brovns Ferry Nuclear Plant Route 12, Box 637 Athens, Alabama 35611 Mr. Thierry M. Ross, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region II l'.'1 Marietta Street, NW, Suite 2900 Ati'nta, Georgia 30323
l w
ENCLOSURE BROWNS FERRY-NUCLEAR PLANT HEATING, VENTILATION AND AIR CONDITIONING (HVAC)
SEISMIC DESIGN CRITERIA 1.
NRC Ouestion Clarify section 1.3.1.3 of the Class I HVAC Seismic Design Criteria (BFN-50-C-7104) with respect to the methodology for summation of two sets of seismic forces.
TVA Response Section 1.3.1.3 of the Class I KVAC Seismic Design Criteria has
-been revised to more clearly explain the methodology to be used in the determination of the resultant of two sets of loading combinations. The revised section reads as follows:
1.3.1.3
" Design and evaluation of the ductwork shall be performed uSing the Housner Response Spectra from the Master Acceleration Response Spectra (MARS) Report (Reference 1.9.8).
Seismic forces from the vertical and esch of the two orthogonal horizontal earthquake components, i.e.,
East-West nad North-South, will be determined. The seismic. design of the duct and supports will be based on
-forces from an earthquake with the vertical and one of the horizontal components. The governing resultant seismic forces shall be the larger of the absolute sums (ABS) of the vertical with one of the horizontal component earthquake forces."
2.
NRC Ouestion Does the Class.I HVAC Seismic Criteria adequately accommodate normal operating and accident load combinations-(excluding earthquake loads)?
TVA Response Section 1.6 on page I-7, Section 1.7.1 on page I-8, and paragraph 1 of Section 1.8.1 on page I-9 of the Class I HVAC Seismic Design Criteria have been revised to require. evaluation for normal operating conditions and to specify allowables to be used in the-evaluation. The revised sections read as follows:
1.6 DESIGN LOADING COMBINATIONS FOR DUCTWORK AND SUPPORTS "Ductwork and supports shall be designed for normal and emergency loading conditions.
In general, the normal condition consists only of dead load, and the emergency condition is the combination of dead load and DBE (SSE) seismic loads.
For ductwork exposed to weather, it may be necessary to consider additional loads due to weather effects such as wind L
or tornado depressurization.
All loading combinations shall be by absolute sum (ABS)."
l'
Page 2 TVA Response (continued) 1.7.1 E_tndlDE
" Bending stresses in ductwork shall be limited to the following allowables:
Rectangular duct: 8000 psi, normal condition 12000 psi, emergency condition Round duct: 10000 psi, normal condition 15000 psi, emergency condition" 1.8.1 Allowable Stresses for Suppotts
" Allowable stresses for normal condition loads for structural steel, connection bolts, and welds shall be as specified in the AISC manual (Reference 1.9.7).
These allowables may be increased by 1.5 for emergency condit!an loads. However, in no case shall allow'.bles after the increase exceed 90 percent of the specified rdnimum yield stress for steel for tension and bending, 90 percent of critical buckling for axial comprecsion,or0.9F/\\f3'forshear,includingshearonbase y
metal for welded connections."
m
______________..-______s
_ _.