ML20149H216: Difference between revisions

From kanterella
Jump to navigation Jump to search
(StriderTol Bot insert)
 
(StriderTol Bot change)
 
Line 1: Line 1:
{{Adams
#REDIRECT [[NSD-NRC-97-5242, Forwards Response to NRC Question Re Dser Open Item 3.7.3.2-2 on Equivalent Static Analysis & Response to RAI 720.391 on Seismic Margin for Containment Air Baffle]]
| number = ML20149H216
| issue date = 07/21/1997
| title = Forwards Response to NRC Question Re Dser Open Item 3.7.3.2-2 on Equivalent Static Analysis & Response to RAI 720.391 on Seismic Margin for Containment Air Baffle
| author name = Mcintyre B
| author affiliation = WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
| addressee name = Quay T
| addressee affiliation = NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
| docket = 05200003
| license number =
| contact person =
| document report number = NSD-NRC-97-5242, NUDOCS 9707240279
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE
| page count = 3
}}
 
=Text=
{{#Wiki_filter:-
                                                                                      /
y.
w$
8    **#8#3" "
tr COI Oratl0fl NSD-NRC-97-5242 DCP/NRC0963 Docket .No.: 52-003
          .                                                                                      July 21,1997 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: T. R. QUAY
 
==SUBJECT:==
.        RESPONSE 51O QUESTIONS ON STRUCTURAL AND SEISMIC MARGIN OPEN ITEMS
 
==Dear Mr. Quay:==
 
Attached is the response to an NRC staff question about DSER open item 3.7.3.2-2 (OITS #672) on equivalent static analysis. Also attached is the response to RAI 720.391 (OITS# 5504) on seismic margin for the containment air baffle.
The SSAR changes in the response to DSER open item 3.7.3.2-2 will be included in SSAR Revision 15.
The Westinghouse status column in the OITS for DSER open item 3.7.3.2-2 (OITS #672) and RAI
          .720.391 (OITS# 5504) will be changed to Action N. The NRC should review these responses and inform Westinghouse of the status to be designated in the NRC status column of the OITS.
Please contact Donald A. Lindgren at (412) 374-4856 if you have any questions LY$
11rian A. McIntyre, Manager Advanced Plant Safety and Licensing jml Attachment                                                                                          A cc:    . J. M. Sebrosky, NRC (w/ Attachment)
                    .N. J. Liparuto, Westinghouse (w/o Attachment) 9707240279 970721 PDR      ADOCK 05200003' me h h,h h b
 
                                                                                                                        ~
        'a
    },.
                ,    ,,                                      Attachment to Westinghouse Letter DCP/NRC0963 DSER Open Item 3.7.3.2-2 (OITS #672)
Westinghouse should justify the adequacy of using the equivalent static analysis method for the                      ,
analysis of subsystems (steel platforms and frames).
              - Westinghouse Response 1
SSAR subsection 3.7.3 was revised in Revision 7 to clari_y methods used for the analysis of subsystems. Subsection 3.7.3.3 describes the methods of dynamic analysis for complex subsystems.
Subsection 3.7,3.5 describes the equivalent static analysis methods for simple systems.
Westinghouse does not use equivalent static analysis for complex non-rigid steel platforms and frames supporting seismic Category I equipment. Subsection 3.7.3.3 is revised below to show dynamic analyses for such frames.
SS R Revision
    .        Add new paragraph as follows at end of subsection 3.7.3.3:
Dynamic models are prepared for the following seismic Category I steel structures. Response spectrum or time history nalyses are performed for structural design. Time history analyses are        .
performed where floor response spectra are required for the decoupled analyses of piping or components described in subsection 3.7.3.8.3,                                                                          l
                                                                                                                                      )
* Passive containment cooling valve room (roon) number 12701)                                                  ,
* Steel framing around steam generators                                                                          j e      ' Containment air baffle t
1                                                                  8 e
a I
no .,<
 
i                                                                Attachment to !!estinghouse Letter DCP/NRLW63
't NRC REQUEST FOR ADDITIONAL INFORMATION N
Question: 720.391 A possible failure mechanism of passive containment cooling is the blockage of the baffle as a result of a seismically induced blockage of the drain system (not included in the SMA). The opening of the PCCWST air-operated valves (due to loss of compressed air upon loss of offsite power) would release water which would block the bafHe if the drain system fails due to the seismic event. Westinghouse should evaluate and discuss the feasibility of this containment cooling failure mechanism.
 
===Response===
As stated in SSAR subsection 6.2.2.2.4, "the li CS] cooling water not evaporated from the vessel wall Hows down to the botton of the inner containment annulus into floor drains. 'Ihe redundant floor drains route the excess water to storm drains. The drain lines are always open (without isolation valves) and each is sized to accept maximum passive containment cooling system flow. 'the interface with the storm drain system is an open connection such that any blockage in the storm drains would result in the annulus drains overflowing the connection, draining the annulus independently of the storm drain system."
The annulus Door drains are essentially pipes embedded into the wall of the shield building. The water travels through the pipe to the outside of the shield building. The interface with the storm drain system is an open connection, meaning the water can either travel down a pipe (like a downspout) to the storm drain or if the storm -
drain or "downspout" pipe is blocked, the water simply overflows through the opea end of the drain pipe that is located outside the shield building, and dumps onto the ground. Thus, success of the safety-related drains is independent of the availability of the storm drain system. Rather, success of the annulus drains is dependent on the shield building integrity.
The PCS, including the annulus drains,is part of the shield building structure which is qualified as Seismic Category I.
Since the annulus drain is embedded within the shield building concrete wall, it is covered by the shield building HCLPF. Seismic failure of the PCS is modeled in the seismic margin analysis, and it is assumed (see Table 55-3, sheet 4 of 4) that the shield building wall HCLPF is conservatively the same as the shield building roof HCLPF.
The shield building HCLPF is dominated by the shield building roof and has a calculated HCLPF of 0.58g.
Thus, the sequence postulated in this RAI, of the drain system failing due to the seismic event leading to water blocking the PCS air bafde, is not a feasible seismic failure mechanism of the PCS. Water will still drain out the shield building onto the ground if the storm drain lines are blocked or failed due to the seismic event. The annulus drain can only fail when the shield building wall itself fails.
PRA Revision: None.
T Westinghouse}}

Latest revision as of 13:43, 11 December 2021

Redirect to:

Retrieved from "https://kanterella.com/w/index.php?title=ML20149H216&oldid=3360130"