ML20133G109
| ML20133G109 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 01/08/1997 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9701150154 | |
| Download: ML20133G109 (5) | |
Text
_
- ~
o Dave M!r:y Southern Nucl:ar
, Vice President 0 pirating Company FarleyProject P0. Box 1295 Birmingham, Alabama 35201 Tel 205.992.5131 k
January 8,1997 SOUTHERN h COMPANY Docket Nos.: 50-348 50-364 10 CFR 50.46 U. S. Nuclear Regulatory Commission ATrN: Document Control Desk Washington, DC 20555 Joseph M. Farley Nuclear Plant Peak Clad Temperature (PCT ) Calculation i
q Ladies and Gentlemen:
Southern Nuclear Operating Company (SNC) was recently informed of a SBLOCA model error associated with auxiliary feedwater flow in the calculation of PCT for Farley Nuclear Plant Units 1 and 2. In order to offset this error, credit was taken for Farley-specific safety injection flows instead i
ofgeneric safety injection flows. This analysis is complete. The absolute values of the accumulated penalties resulting from the error and changes are 148 F for Unit I (up-flow configurtsion) and 137 F for Unit 2 (down-flow configuration). The algebraic sums of the accumulated PCT penalties are -
48 F for Unit I and -37 F for Unit 2. Accordingly, SNC has determined that the above accumulated penalties constitute significant errors and changes in the SBLOCA analyses for both Farley units and i
are reportable under 10 CFR 50.46 to the NRC. Compliance with the requirements of 10 CFR 50.46 continues to be met.
Attachment I provides the current SBLOCA PCTs for Farley Unit I and Unit 2. Attachment 2 provides additional details on the model error and changes.
Respectfully submitted, 1
{Ib hl4%
l REM:maf/30DAYPCI. DOC Attachments cc:
Mr. L. A. Reyes, Region II Administrator Mr. J. J. Zimmerman, NRR Project Manager Mr. T. M. Ross, Plant Sr. Resident Inspector 9701150154 970108 PDR ADOCK 05000340 p
.w,
1
=
9' e
1 ATTACHMENT 1 JOSEPH M. FARLEY NUCLEAR PLANT UNITS 1 AND 2 SMALL-BREAK LOCA ANALYSES PCT ( F) l 1
~
ATTACHMENT 1 JOSEPH M. FARLEY NUCLEAR PLANT 2
SMALL-BREAK LOCA PCT ( F) s UNIT 1,*F UNIT 2,*F A. ANALYSIS-OF-RECORD (VANTAGE 5)
- 1. ECCS Analysis 1785*
1763*
- 2. T.v, Temperature Uncertainty 20*
20*
Total Analysis-of-Record PCT =
1805*
1783*
B. 10 CFR 50.46 MODEL ASSESSMENTS
- 1. Prior Reported Assessments 280*
141*
- 2. AFW Flow Reduction to 295 gpm 50 50
- 3. Evaluation for Plant-Specific HHSI Flows
-73
-73
- 4. Change in Burst and Blockage /fime in Life
-25 "
-14" i
i C. 10 CFR 50.59 PLANT MODIFICATIONS None 0
0 l
D. TOTAL RESULTANT SMALL-BREAK LOCA PCT 2037 1887 4
1 Reported to the NRC under the 10 CFR 50.46 Significant Error Report in Reference 1.
" For Burst and Blockagefrime in Life, penalties of 121*F for Unit I and 45*F for Unit 2 were included in B.1 above as previously reported to the NRC in Reference 1. Item B.4 is the sum of the associated changes in the Burst and Blockagefrime in Life penalty due to items B.2 and B.3 (see the note in Attaclunent 2) since the Burst and Blockagefrime in Life penalty is a function of PCT. Thus, the total penalties for Burst and Blockagefrime in Life are 96 F for Unit I and 31*F for Unit 2.
Reference 1:
Letter from SNC to USNRC, " Joseph M. Farley Nuclear Plant, Peak Clad Temperature (PCT) Calculation," August 12,1996.
9 i
e ATTACHMENT 2 DISCUSSION OF SMALL-BREAK LOCA MODEL ERROR AND CHANGES
ATTACHMENT 2 i
l DISCUSSION OF SMALL-BREAK LOCA MODEL ERROR AND CHANGES l
A. NOTRUMP INPUT ERROR
- 1. AFW Flow Reduction to 295 gpm (50 F)
During the ongoing power uprate SBLOCA analysis, an error associated with input assumptions related to the current Farley Auxiliary Feedwater (AFW) system design was discovered. The latest evaluation, reported by letter dated August 12,1996, used an AFW flow of 650 gpm. This SBLOCA analysis should not have credited rated flow of the TDAFW pump in conjunction with the initiating event. The correct flow rate should be 295 gpm. A conservative evaluation of the impact on the current SBLOCA PCT, using 295 gpm for total AFW flow (IMDAFW pump), has resulted in a 50 F penalty for both Unit I and Unit 2. It should be noted that flow in excess of 295 gpm is available through the TDAFW pump; however, no credit for this pump is taken in the current accident analyses.
B. NOTRUMP EVALUATION
- 1. Evaluation for Plant-Specific HHSI Flows Credit was taken for Farley-specific high head safety injection (HHSI) flows, with appropriate margins, as opposed to the very conservative generic flows used in an existing evaluation for a safety injection line imbalance at Farley Units I and 2. When the plant-specific degraded flows are used, a 73 F PCT benefit results, which is used to ofTset the reduced auxiliary feedwater flow penalty.
Note: Associated with the above NOTRUMP input error and NOTRUMP evaluation is a change in the current Burst and Blockage / Time in Life penalty since the magnitude of this penalty is a j
ftmetion of PCT (a 25 F penalty decrease for Unit I and a 14 F penalty decrease for Unit 2).