ML20217G601
| ML20217G601 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 12/31/1997 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML20217G571 | List: |
| References | |
| NUDOCS 9804290173 | |
| Download: ML20217G601 (13) | |
Text
1 j
Comed 10 CFR 50.46 Report PLANT NAME:
Braidwood Station Unit 1 ECCS EVALUATION MODEL:
Small Break LOCA REPORT REVISION DATE:
4/1/98 CURRENT OPERATING CYCLE: 2 ANALYSIS OF RECORD
)
Evaluation Model: NOTRUMP 1
Calculation: Westinghouse SEC-SAll-4730-CO, May,1995 Fuel: VANTAGE 5/ VANTAGE + 17 x 17 l
FQ = 2.60 FNAll = 1.70 SGTP = 30%
Reference PCT PCT = 1723.0 F MARGIN ALLOCATION j
A. PRIOR LOCA MODEL ASSESSMENTS NOTRUMP Specific Enthalpy Error (Note 5)
APCT =
20.0 F SALIBRARY Double Precision Error (Note 6)
APCT =
-15.0 F SBLOCTA Fuel Rod Initialization Error (Note 7)
APCT =
10.0 F
{
Burst and Blockageffime in Life (Note 3)
APCT =
30.0 F l
Missing Grid Piece (Note 1)
APCT =
17.0 F
{
B. CURRENT LOCA MODEL ASSESSMENTS Removal of Missing Grid Piece (Note 1)
APCT =
-17.0 F NET PCT PCT = 1768.0 F l
t 9804290173 980423 PDR ADOCK 05000454 R
PDR i
Comed 10 CFR 50.46 Report PLANT NAME:
Braidwood Station Unit 1 ECCS EVALUATION MODEL:
Larce Break LOCA REPORT REVISION DATE:
4/1/98 CURRENT OPERATING CYCLE: 2 ANALYSIS OF RECORD Evaluation Model: BASII Calculation: Westinghouse SEC-SAll-4747-C2, July,1996 I
Fuel: VANTAGE 5/ VANTAGE + 17 x 17 l
FQ = 2.60 FNAli = 1.70 SGTP = 30%
Reference PCT PCT = 1968.0 F l
l MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS Translation of Fluid Conditions from SATAN to LOCTA (Note 8)
APCT =
15.0 Missing Grid Piece (Note 1)
APCT =
17.0 F B. CURRENT LOCA MODEL ASSESSMENTS l
RCS Crossover Leg Volume (Note 9)
APCT =
3.0 l
Removal of Missing Grid Piece (Note 1)
APCT =
-17.0 F NET PCT PCT = 1986.tfF l
l
I
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Comed 10 CFR 50.46 Report PLANT NAME:
Braidwood Station Unit 2 ECCS EVALUATION MODEL:
Small Break LOCA REPORT REVISION DATE:
4/1/98 CURRENT OPERATING CYCLE: 2 ANALYSIS OF RECORD Evaluation Model: NOTRUMP Calculation: Westinghouse SEC-SAll-4730-C0, May,1995 Fuel: VANTAGE 5/ VANTAGE + 17 x 17 FQ = 2.60 FNAH = 1.70 SGTP = 30%
Reference PCT PCT = 1723.0 F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS NOTRUMP Specific Enthalpy Error (Note 5)
APCT =
20.0 F SALIBRARY Double Precision Error (Note 6)
APCT =
-15.0 F SBLOCTA Fuel Rod Initialization Error (Note 7)
APCT =
10.0 F l
Burst and Blockage / Time in Life (Note 3)
APCT =
30.0 F B. CURRENT LOCA MODEL ASSESSMENTS NET PCT PCT = 1768.0 F 1
l
Attaclunent 1 Comed 10 CFR 50.46 Report PLANT NAME:
!)raidwood Station Unit 2 ECCS EVALUATION MODEL:
Laree Break LOCA REPORT REVISION DATE:
_4/1/98 CURRENT OPERATING CYCLE: 2 ANALYSIS OF RECORD Evaluation Model: BASli Calculaticn: Westinghouse SEC-SAII-4747-C2, July,1996 Fuel: VAN i AGES / VANTAGE + 17 x 17 FQ = 2.60 FNAll = 1.70 SGTP = 30%
Reference PCT PCT = 1968.0 F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS Translation of Fluid Conditions from SATAN to LOCTA (Note 8)
APCT =
15.0 F H. CURRENT LOCA MODEL ASSESSMENTS Crossover Leg Volume (Note 9)
APCT =
3.0 F NET PCT PCT = 1986.0 F f
l t
i Comed 10 CFR 50.46 Report PLANT NAME:
Byron Station Unit 1 ECCS EVALUATION MODEL:
Small Break LOCA REPORT REVISION DATE:
4/1/98 CURRENT OPERATING CYCLE:
9 ANALYSIS OF RECORD Evaluation Model: NOTRUMP Calculation: Westinghouse SEC-LIS-5314-C0, October 31,1997 Fuel: VANTAGE 5/ VANTAGE + 17 x 17 FQ = 2.60 FNAli = 1.70 i
SGTP = 30%
Reference PCT PCT = 1695.0 F MARGIN ALLOCATION l
A. PRIOR LOCA MODEL ASSESSMENTS None H. CURRENT LOCA MODEL ASSESSMENTS None NET PCT PCT = 1695.0*F l
l
Comed 10 CFR 50.46 Report PLANT NAME:
Byron Station Unit 1 ECCS EVALUATION MODEL:
Larce Break LOCA REPORT REVISION DATE:
4/1/98 CURRENT OPERATING CYCLE:
9 ANALYSIS OF RECORD Evaluation Model: BASH Calculation: Westinghouse SEC-SAll-4747-C2, July,1996 Fuel: VANTAGE 5/ VANTAGE + 17 x 17 FQ = 2.60 FNAlI = 1.70 SGTP = 20% (Note 10)
Reference PCT PCT = 1968.0 F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS Removed Upper Internal Assembly Alignment Pins (Note 2)
APCT =
5.0 F Assembly Guide Pin Flakes (Note 4)
APCT =
6.0 F l
Translation of Fluid Conditions from SATAN to LOCTA (Note 8)
APCT =
15.0 F
{
l H. CURRENT LOCA MODEL ASSESSMENTS RCS Crossover Leg Volume (Note 9)
APCT =
3.0 F l
Replacement Steam Generator (RSG)(Note 10)
APCT =
21.0 F NET PCT PCT = 2018.0 F t
i
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Comed 10 CFR 50.46 Report J
PLANT NAME:
Byron Station Unit 2 ECCS EVALUATION MODEL:
Small Break LOCA REPORT REVISION DATE:
4/1/98 CURRENT OPERATING CYCLE: 2 ANALYSIS OF RECORD Evaluatiots Model: NOTRUMP Calculation: Westinghouse SEC-SAll-4730-C0, May,1995 Fuel: VANTAGE 5/ VANTAGE + 17 x 17 I
FQ = 2.60 FNAll = 1.70 SGTP = 30%
Reference PC f PCT = 1723.0 F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS NOTRUMP Specific Enthalpy Error (Note 5)
APCT =
20.0 F SALIBRARY Double Precision Error (Note 6)
APCT =
-15.0 F SBLOCTA Fuel Rod Initialization Error (Note 7)
APCT =
10.0 F Burst and Blockage / Time in Life (Note 3)
APCT =
30.0 F B. CURRENT LOCA MODEL ASSESSMENTS None NET PCT PCT = 1768.0'F
- Attachment 1 Comed 10 CFR 50.46 Report Pl. ANT NAME:
Byron Station Unit 2 ECCS EVALUATION MODEL:
Larce Break LOCA REPORT REVISION DATE:
4/1/98 CURRENT OPERATING CYCLE:
7 ANALYSIS OF RECORD Evaluation Model: basil Calculation: Westinghouse SEC-SAll-4747-C2, July,1996 Fuel: VANTAGE 5/ VANTAGE + 17 x 17 FQ = 2.50 FNAll = 1.65 SGTP = 30%
Reference PCT PCT = 1968.0 F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS Removed Upper Internal Assembly Alignment Pins (Note 2)
APCT =
28.0 F Translation of Fluid Conditions from SATAN to LOCTA (Note 8)
APCT =
15.0 F H. CURRENT LOCA MODEL ASSESSMENTS RCS Crossover Leg Volume (Note 9)
APCT =
3.0 F NET PCT PCT = 2014.0 F I
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l
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l Comed 10 CFR 50.46 Report l
Assessment Notes l
- 1. Missine Grid Piece l
This penalty is the result of potential flow blockage at a fuel assembly lower nozzle due to unrecovered det:is in the reactor. The debris is a small (approximately 0.5 inches i
square) piece of a torn grid strap from assembly C22S. This assembly was damaged during fuel movement following Braidwood Unit 1 Cycle 2. This penalty applies to
)
Braidwood Unit 1 only. During refueling outage AlR06, an extensive lower internal
)
inspection was performed, the inissing grid piece was not found, and it is assumed that l
the missing piece is not in the RCS. The 17 F penalty is removed during this revision date. (T. Tulon to T. Rieck, "LOCA Penalties due to Missing Grid Piece," dated April 22, 1997)
- 2. Removed Unner Internal Assembly Alienment Pins This penalty addresses the removal of upper internals alignment pins at Byron Station.
Two pins have been removed from Byron Unit I and six pins have been removed from Byron Unit 2. Removal of the alignment pins resulted in a LBLOCA PCT penalty of
+5.0 F for Byron Unit 1. Byron Unit 2 previously accounted for the cut pins by penalizing FQ. Starting with Byron Unit 2 Cycle 6 a LBLOCA PCT penalty of +28.0 F was assessed instead of the FQ penalty. This will establish consistent treatment of the cut alignment pins for both Byron units.
- 3. Burst and Blockacerrime in Life l
Typically the Small Break LOCA was performed using BOL fuel performance data l
(PAD) and evaluated at other burnups using the SPIKE code. Presently this is explicitly l
modeled using a " time in life study." The burst and blockage model does not have any effect on the PCT if the PCT is less than 1700 F. As a result of the NOTRUMP specific i
enthalpy error (Note 6), the SBLOCTA fuel rod initialization error (Note 8), and SALIBRARY double precision error (Note 7), a 30 F burst and blockage / time in life penalty is applicable to the Small Break LOCA for Braidwood and Byron.
Comed 10 CFR 50.46 Report Assessment Notes
- 4. Assembly Guide Pin Flakes Bending of fuel assembly alignment pins to angles greater than 5 degrees may result in the generation of pin flakes or fragments. The flakes could potentially lodge themselves in an assembly and locally reduce assembly flow. The flakes could increase blockage of the hot rod subchannel during the reflood period and increase the PCT. This penalty is
)
only applicable to Byron Station Unit 1.
- 5. NOTRUMP Snecific Enthalov Error 1
A typographical error was found in a line of coding in the NOTRUMP code. This line of
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coding was intended to model the calculation found in Equation L-127 of WCAP-10079P-A. Although the equation in the topical report is correct, the coding 3
represented the last term as a partial derivative with respect to the fluid node mixture
{
region total energy instead of the mixture region total mass. This 20 F penalty applies to j
the SBLOCA analyses for Braidwood and Byron.
- 6. SALIBRARY Double Precision Errors During migration of the LOCA codes from the CRAY computer to UNIX-based platforms, programming errors were made in two library routines related to improper specification of double precision variables. These errors were found and fixed during later code maintenance. Test cases with individual codes in the models demonstrated j
very small differences in only the SATAN and NOTRUMP code results, with correspondingly minor effects on final peak clad temperature predictions. Because the error only affects a very limited number of LBLOCA analyses which were performed on the UNIX platform prior to correcting the codes, the evaluation of effects for LBLOCA j
analyses were assessed on a plant-specific basis. The LBLOCA analyses for Byron and 4
Braidwood were not affected. For SBLOCA analyses performed on the UNIX platform, l
representative plant calculations resulted in an estimated generic effect of-15 F for affected analyses-. This error applies to the SBLOCA analyses for Braidwood and Byron.
- 7. SBLOCTA Fuel Rod Initiali7.ation An error was discovered in the SBLOCTA code related adjustments which are made as part of the fuel rod initialization process which is used to obtain agreement between the SBLOCTA model and the fuel data supplied from the fuel thermal-hydraulic design calculations at full power, steady-state conditions. Specifically, an adjustment to the power, which is made to compensate for adjustments to the assumed pellet diameter was incorrect. Additionally, updates were made to the fuel rod clad creep and strain model to i
correct logic errors that could occur in certain transient conditions. These model revisions also had a small affect on the fuel rod initialization process, and can produce small affects during the transient. Due to the small magnitude of the affects, and the interaction between the two items, they are being evaluated as a single, closely related affect. Calculations with the corrected model resulted in an increase of 10"F in the PCT for the Small Break LOCA. This penalty applies to Braidwood and Byron.
8 Translation of Fluid Conditions from SATAN to LO_CTA
Comed 10 CFR 50.46 Report Assessment Notes An error was discovered in the coding related to the translation of fluid conditions between the SATAN blowdown hydraulics code and the LOCTA code used for subchannel analysis of the fuel rods. In performing axial interoolations to translate the SATAN fluid conditions onto the mesh nodalization used by the LOCTA code, the length of the lower core channel fluid connection to the lower plenum node was incorrectly calculated. Calculations with the corrected model resulted in an increase of 15 F in the PCT for the Large Break LOCA. This penalty applies to Braidwood and Byron.
- 9. RCS Crossover Lee Volume IMP is an electronic database containing a variety of plant geometry data whose primary purpose is to interactively support the LOCA Evaluation Model input preprocessors.
j Secondary purposes are to provide a convenient repository and ready reference for NSSS geometry information for a variety of functional groups that generally valize the database I
simply for limited hand data extractions. Westinghouse discovered an c.rror in a recent edition of the Byron /Braidwood IMP Database associated with the crossover leg volume.
The IMP Database has been subsequently updated.
The impact of the error is a 3 F in the LBLOCA PCT. The SBLOCA analysis of record bounds the increased crossover leg v 'ame configuration and there is no adverse impact to SBLOCA PCT. This item applies to Braidwood and Byron. (Westinghouse letters CAE-97-216/CCE-97-298)
]
- 10. Replacement Steam Generator (RSG)
Westinghouse performed an evaluation to demonstrate the applicability of the current i
LBLOCA AOR (SEC-SAII-4747-C2) to the BWI RSGs. The evaluation consisted of evaluating the differences between the BWI and Westinghouse designed steam generators and its impact on the PCT. The evaluation resulted in a 21 F PCT penalty for the BWI RSGs. The RSG supports a steam generator plugging level of up to 20%. This is applicable at this time to Byron Unit 1. (Westinghouse letter CAE-97-225/CCE-97-309)
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i Comed 10 CFR 50.46 Report Assessment Notes Not included in Rack-ups The following is a brief description of other LOCA assessments, which are not included in the rack-up sheets. As necessary, evaluations are performed by Comed or Westinghouse to support minor changes or lojustify continued operations. Evaluations of these changes are based upon conservative generic studies for Westinghouse designed NSSSs or engineeringjudgement. They do not constitute a change to the application of the evaluation models in the current licensing basis for Braidwood or Byron. If Comed obtains a re-analysis or an evaluation from Westinghouse, the impact of these changes will be included and the effect of these changes will be reported as applicable.
I Diesel Generator Under Freauency Evaluation The safety analyses are performed assuming the diesel generator operates at the steady state frequency. Recent diesel generator loading sequence tests and modeling indicate that the under frequency reduction can be as much as 2 Hz (from 57 to 55 Hz) for a period of 4 seconds. The impact of the frequency swing during diesel generator loading sequences was evaluated and was determined to have insignificant impact on the PCT (NFS memo NFS:PSA:98-015).
Diesel Generator Freauency Evaluation Currently, all safety analyses are performed assuming the diesel generator operates at the steady state frequency. Ilowever, the Technical Specifications allows the diesel generator frequency to be within i 1.2 Hz of the steady state frequency of 60 Hz and plant operation will still be acceptable. Byron and Braidwood informed Nuclear Fuel Services (NFS) that the surveillance tests performed to date for the diesel generators at Byron and Braidwood indicate that the frequency for the diesel generators is 60 + 0.4/-0.2 Hz.
Using diesel generator frequency of 60 + 0.4/-0.2 Hz instead of 60 Hz, impacts the ECCS flow rates, AFW flow rate and RCFC performance. Evaluations were performed to assess the impact on the LOCA analysis. It was determined that the PCT penalty would be minimal and would not challenge the NRC acceptance criteria of 2200 "F (NFS:PSA:98-021). Westinghouse will perform a formal assessment of any PCT impact.
This PCT penalty will be reported to the NRC per NFS Procedure T-01 and T-02. This item applies to Byron and Braidwood.
RCFC Performance Analysis Data (Byron NDIT-97-0415)
The RCFC Heat Removal Data and Curves was revised. This revised data resulted in an increase on the heat removal capacity of the RCFC. An operability assessment was performed to determine the impact on the LOCA analysis of record (Operability Evaluation 97-122). Westinghouse will perform a PCT assessment with revised RCFC heat removal capacity information. Any impact on the PCT will be reported to the NRC per NFS Procedure T-01.
Comed 10 CFR 50.46 Report Assessment Notes Not included in Rack-ups Containment Ileat Sink Revised Surface Area (Bechtel letter BECE/97-197)
The surface area of uninsulated permanent steel in containment changed due to the Replacement Steam Generators. An evaluation was performed by NFS (NFS:PSA;97-091) to determine the impact on the LOCA analysis. It was determined that the revised surface area has minor impact on PCT. Westinghouse will incorporate the impact of this additional steel when evaluating the impact of the RCFC performance analysis data as mentioned above.
I.BLOCA Power Distribution Appendix K to 10 CFR 50 requires that the power distribution which results in the most severe calculated consequences be used in the ECCS Evaluation Model calculations. The current basis for all Westinghouse large break LOCA evaluations is the chopped cosine power distribution. Calculations were performed with BASII which examined peak power locations and power distributions which were not considered in the original analysis. Under some circumstances, these evaluations lead to PCTs greater than those calculated with the cosine distribution. Previously, Byron and Braidwood Units 1 and 2 a
i:.cluded a conservative temporary penalty of 100 F to bound the effects of other power j
shapes.
To address the power shape issue, Westinghouse has developed an alternate axial power shape methodology, ESIIAPE (Explicit Sliape Analysis for PCT Effects). The ESHAPE methodology is based on explicit analysis of a set of skewed axial power shapes. The explicit use of skewed power shapes has been previously approved by the NRC as part of the Westinghouse's Large Break LOCA Evaluation Model. Westinghouse has performed evaluations for Byron and Braidwood using ESIIAPE and has determined that the cosine I
power shape used in the AOR remains limiting. Therefore, the PCT penalty of 100 F was removed.