ML20215M734
| ML20215M734 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 10/20/1986 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 2NRC-6-110, 86-14, NUDOCS 8611030213 | |
| Download: ML20215M734 (4) | |
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2NRC-6-110 Beaver Valley No. 2 Unit Project Organization S.E.G. Building Telecopy ( 1 3-Ext.160 P.O. Box 328 Oct. 20, 1986 Shippingport, PA 15077 United States Nuclear Regulatory Commission Region I 631 Park Avenue i
King of Prussia, PA 19406 ATTENTION: Dr. Thomas E. Murley Administrator
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Outside Containment Flood Analysis Potential Significant Deficiency Report 86-14 Gentlemen:
This Potentially Reportable Significant Deficiency Report is being submitted pursuant to the requirements of 10CFR50.55(e)
DUQUESNE LIGHT COMPANY By M.
J. J. Carey u l
Sr. Vice President l
RJW/ijr NR/ SIGN /DEF/RPT Attachment AR/NAR l
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cc: Mr. P. Tam, Project Manager (w/a)
Mr. J. M. Taylor, Director (3) (w/a)
Mr. J. Beall, Sr. Resident Inspector (w/a)
Mr. L. Prividy, NRC Resident Inspector (w/a)
INP0 Records Center (w/a)
NRC Document Control Desk (w/a) l 8611030213 861020 PDR ADOCK 05000412 s
PDR j
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ATTACHMENT 1.
Summary The Engineering Assurance Hazards Program Audit has identified an unjustified assumption in the design basis of the outside containment flooding analysis.
Correction of this assunption has increased auxiliary and service building calculated flood heights. Flooding to these heights could submerge certain essential Class 1E components and jeopardize preservation of safe shutdown capabilty.
2.
Immediate Action Taken High energy lines located in Category I areas outside containment were evaluated to ensure proper consideration as potential flood sources.
This evaluation concluded that double ended rupture of the Main Feedwater Lines in the Service Building could impact safe operation of.
j BVPS-2 if no corrective action were taken.
On September 17, 1986, Mr.
R.
J. Wallauer (DLC) notified Mr.
D.
Limroth (Region I,
USNRC) that DLC considered this issue to be potentially reportable under the requirements of 10CFR50.55(e) 3.
Description of Deficiency Project Technical Procedure 2BVM-ll4, "Essentie.1 Systems, Components, and Instrumentation Required for Safety Functions, " establishes the design basis for evaluating the flooding effects of postulated piping f ailures required by Standard Review Plan Section 3.6-1.
A statement in the flooding design basis assumed that 100 percent of process fluid above 212*F would flash to steam if it flowed out of a double ended pipe rupture.
This assumption was not conservative since an analysis of a main feedwater line rupture demonstrates that approximately 25 percent of the process fluid would flash to steam.
4.
Analysis of Safety Implications Reanalysis of a main feedwater line rupture in the service building conservatively assumes that the total volume of the condenser hotwell is deposited on the 780'-6" floor.
Although this produces a 14 inch flood
- neight, no safety-related equipment is affected at this elev ation.
Due to transmission through open doors, collapsed vent ducts, and crumbled walls, this event produces the most limiting flood height in all elevations of the auxiliary and service buildings (See attached FSAR Figure 3.8-46).
The Class 1E equipment which might be submerged by this event in the auxiliary building and the 760'-6"/745'-6" elevations of the service building is not used for plant safe shutdown.
However, the flood height (3.5") in the service building (elevation 730'-6")
might effect floor mounted vital switchgear that is used for safe shutdown capability.
I 5.
Corrective Action To Resolve The Deficiency g
Software:
The outside containment flooding analysis calculation has been revised to evaluate lines previously exempted from analysis.
Project Proce-dure 2BVM-ll4 has been revised to correct the analysis basis.
FSAR Section 3.6 will be reviewed to identify any revisions needed to reflect the change in calculated flood height.
Hardware:
The following construction changes are being implemented to mitigate the flooding effects of a main feedwater line break on the service building.
1.
Vent Duct Flood Barriers Flood barriers (Dikes) will be constructed around all service building 780'-6" vent duct floor penetrations to contain the 14-inch flood height.
2.
Door Gaskets Four doors will be gasketed at elevation 780'-6" and 745'-6".
3.
Electrical Floor Barriers Flood barriers (Dikes) will be installed around the bottom row of breakers in 480 V vital switchgear cabinets 480 V US*2-8 and 2-9 at elevation 730'-6" 4.
Blowout Panel l
Installation of a blowout panel in the service building wall has i
previously been identified as being required to mitigate the j
environmental (i.e., temperature / pressure) effects of a main stean line failure.
The panel will be installed flush with the 780'-6" floor to mitigate both environmental and flooding effects.
6.
Additional Reports No additional reports are anticipated.
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2* 2 EP FIGURE 3.8-46 SERVICE BUILDING SECTIONS l-l AND 2-2 BEAVER VALLEY ;OWER STATION-UNIT 2 FINAL SAFETY ANALYSIS REPORT
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