ML19254E985
| ML19254E985 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 10/15/1979 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML19254E983 | List: |
| References | |
| NCR-CEB-79-19, NUDOCS 7911050293 | |
| Download: ML19254E985 (5) | |
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ENCLOSURE SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 DBA MOVEMENTS OF SCV NCR CEB 79-19
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FINAL REPORT Descriotion of De i;jency Piping which penetrates the steel conta;ncent (SCV) with rigid penetrations or is rigidly attached to S V was analyzed and designed without adequate consideration for design basis accident (DBA) mvements of SCV.
Specifically, earlier analysis and desi;;n of piping systems penetrating the steel vessel.ncorrectly accounted for the following:
(1) Most piping systems which penetrate the steel vessel are supported by rigid pipe supports, springs, and/or by mechanica? seismic supports (snubbers).
However, the contain=ent and piping response to earthquake retion is rapid enough to cause the snubbers to lock up thereby preventing covement of the pipes.
In the original analysis of the piping, it was assumed that the snubbers would not lock up during the accident condition.
(2) The displacement of the vessel wall and attached piping (at the point of attachment) was incorrectly assumed to be only cutward for the analysis and design of certain piping systems where tave-ment of the vessel wall was considered.
However, inward movement cf the containment vessel cust also be considered where vessel wall movement is important.
(3)
In the original analysis of Sequoyah and Jatts Ear piping syste=s, TVA's analysis approach was to conservatively analyce for containment vibratory notion during a DBA inside containnent using static displacements. This analysis was consistent with the analysis a;proach and philosophy which was used at that time for free standing steel containment buildings and was judged to be adequate to encocpass inertini effects.
It has recently been determined that acceleration ef fects due to the rapid vibratory movenant of the containment vessel may not be adequately considered by the stacic analysis.
The attached table lists the piping systens by penetrations enich are to be reanalyzed to correct this nonconf ormance.
All piping systems listed nust be re2nalyzed to account for the inertial effects.
This reanalysis will envelope any corrective action for the displace:ent problem.
Piping which must be reanalyzed for snubber lockup are identified in the table.
P00R BGINM 7911050 d 5
- 1269 275
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Safety Implications Statement liad this condition gone uncorrected, certain piping systems would have result been overstressed during a DBA and could, as a consequence, in a breach in containment integrity.
This could have adversely affected the safe operation of the plant.
Corrective Action each con-TVA has generated ti=e history and response spectra data at nozzle location for each of the six primary system DBA's.
tain.t:nt Using this information, all piping systems having rigid penetrations through the SCV are being reanalyzed giving full consideration for the being examined with respect DEA event. Also, the new DBA movements are to bellot.s type panetrations by both TVA and the bellows penetration
!!o problems are anticipated with these penetrations.
vendor.
1.
is in the final docu entation stage for unit The analysis effort 2.
%here necessary, supports Analysis is still in progress for unit All analysis, for piping systems are being relocated or redesigned.
23, 1979, for design, and construction will be completed by :;ove=ber unit 1 and before fuel loading for unit 2.
?00R031NAL 1269 276
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SEQUOY All MuCLEA R PLANT Pipine Penetrations Affected by NCR CEB 79-19 Affected by Sys Reqd for Pipe Snubber Lockup Safe Shutdoun Penet r a t io n Service _
11 u mb e r System
- Size X
16 CVCS (Supply) 3 Normal charging to Regen IIx 29 CCS (Disch) 6 R.C.
Pump 011 Cooler X**
X 35 CCS (disch) 6 Excess Letdown lix X
1 N2 to Accumulators X
39A WDS Pressure Relief Tank X
.75 N2 to X
39B WDS 40A AFW (Supply) 4 Auxiliary Feedwater X
X 40B AFW (Supply) 4 A xiliary Feeduater X
400 CSAS (Supply) 3 A r supply f o r 112 Purge X
3 Ficor Sump Pump Discharge X
3 Pressurizer Relief Tank Makeup 41 WDS 42 PWS CN 43A CVCS (Supply) 2 Scalvater Injection - RC Pump psy so 43B CVCS (Supply) 2 Scalvater Injection - RC Pump 43C CVCS (S up ply )
2 Sealvater Inj ect ion - RC Pump bd 43D CVCS (Supply) 2 Scaluater Inj ect io n - RC Pump 44 CVCS (Disch) 4 Scalwa te r Return - RC Pump X
X
[j 4BA Containment Spray 12 Spray lle ad e r X
X 48B Containment Spray 12 Spray lle ad e r X
X 8
Spray lle ade r X
X 49A RilR Spray 8
Spray lic ad e r 49B RilR Spray SOA CCS (Disch) 3 RC Pump Thermal narrice "9C2 SDB CCS (Supply) 3 RC Pump Thermal Barrier 4
S e rv ic e to Standpipe Sys inside Cranevil Sz CCS (supply) 6 RCP, CRon, Louer Cont vent Cooler x
51 FPS
("")
X**
X 53 CCS (Supply) 6 Excess Lecdoun lix C"")3 56 ERCW (Supply) 6 RCP, CRDti, Louer Cont Vent Cooler X
- C vent Cooler x
57 ERCw (Disch) 6 RCe, CRDn, touer Cont
C"")3 6
RCP, C RDil, Louer Cont Vent Cooler X
60 ERCW (Supply) 6 RCP, C RD rl, Louer Cont Vent Cooler X
59 ERCW (Disch)
"hh].
6 RCP, CRDt!, Lower Cont Vent Cooler X
62 ERCW (Supply) 6 RCP, CRDtl, Lower Cont Vent Cooler X
"23[
61 ERCW (Disch) 3 y=""
63 ERCW (Disch) 6 RCP, C it Dil, Lower Cont Vent Cooler X
p X
2 Instrument Room Vent Cooler X
64 ACS j
2 Instrument Roon Vent Cooler 65 ACS
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S S EQ UO Y All NUC. EAR PLANT
_ Piping Penetrations Affected by NCR CEB 79-19 Penetration Pipe Affected by Sys,Reqd for Number System
- Size Service Snubber Lockup Safe Shutdown 66 ACS 2
Instrument Roou Vent Cooler X
67 ACS 2
Instrument Room Vent Cooler X
68 ERCW (Supply) 2 Upper Containment Vent Cooler X
69 ERCW (Supply) 2 Upper Containment Vent Cooler X
70 ERCW (Disch) 2 Upper Containment Vent Cooler X
71 ERCW (Disch) 2 Upper Containment Vent Cooler X
72 ERCU (bisch) 2 Upper Containment Vent Cooler X
73 ERCW (Disch) 2 Upper Coutainment Vent Cooler X
74 EnCW (Supply) 2 Upper containment Vent Cooler X
75 ERCW (Supply) 2 Upper Containment Ve r. t Cooler X
76 CSAS 2
Service Air 77 DWS 2
Demineralized Water X
78 iPS 4
Service to RCP Spray Coverage psy 82 Fuel Pool Cooling 6
From Refueling Cavity X
CN 83 Fuel Pool Cooling 4
To Ref uleing Cavity X
s4) 110 Ull I (Supply) 2 Ull I Valve Test Line 114 1CS 2
Clycol Floor Cooling X
PJ 115 ICS 2
Clycol Floor Cooling X
-w CO "lE
- Fo r desc ription o f acronyms,
see next page.
C C:"**The CCS piping between the excess letdown heat exchanger and the steel containment vessel is J
EC TVA Class B and is required to f unction as a containment boundry (i.e.,
a closed system).
It is for this reason that it is ind ica ted as required for safe shutdown.
The fanction of supplying
{hhh and discharging CCS water to and from the heat exchanger is not required for safe shutdown.
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g S EQUO Y All NUCLEAR l'LANT P i p i n ;. Penetracions-Affected by N C l4 CFB 79-19 Ae ro nvin n Systen CVCS Chemical Volune and Control System CCS Component Cooling System WDS Waste Disposal' System AFW Auxiliary Feedwater System PWS Primary Water Systen ICS Ice Condenser System FPS Fire Protection System ERCU Cssential Raw Cooling Systen DWS Deuineralized Uater Systen Ull i Upper llead Injection System ACS Air-Conditioning / Chilled Water System CN 4
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%4 NO "1[3 C"3 CD M
CD
- A:3 Cr3 ERE 3:=
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