ML20101G071
| ML20101G071 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 03/19/1996 |
| From: | Maynard O WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| WO-96-0047, WO-96-47, NUDOCS 9603270044 | |
| Download: ML20101G071 (7) | |
Text
b WF4LF CREEK NUCLEAR OPERATING CORPORATION March 19, 1996 Otto L Maynard Vu:e Pres # dent Plant Opersons WO 96-0047 U.
S Nuclear Recy.11atory Commission ATTN: Document Control Desk Mail Station P1 137 Washington, D.
7.
20555
Subject:
Docket No. 50-482:
10 CFR 50.46 Annual Report of ECCS Model Changes Gentlemen:
This letter describes changes to the Emergency Core Cooling System (ECCS)
Evaluation Models and the estimated effect on the limiting ECCS analysis for Wolf Creek Generating Station (WCGS) in accordance with the criteria and reporting requirements of 10 CFR 50.46 (a) (3) (i)and (ii), as clarified in Section 5.1 of WCAP-13451, " Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting."
The changes in calculated Peak Cladding Temperatures (PCT) caused by the changes to Westinghouse ECCS Evaluation Models are reportable per 10 CFR 50.46 guidelines, as follows:
1.
For Large Break Losr, of Coolant Accident (LOCA), the net PCT effect of the evaluatio" model changes is O degrees Fahrenheit (OF), for a net PCT of 1971.2 O F, which remains less than the 10 CFR 50.46 limit of 2200 OF.
2.
For Small Break LOCA, the net PCT effeet of the evaluation model changes is +20 OF, for a net PCT of 1590.6 OF, which remains less than the 10 CFR 50.46 limit of 2200 OF.
Attachment I describes the impact of the ECCS Evaluation Model changes.
Attachment II contains the calculated Large Break LOCA and Small Break LOCA PCT margin allocations resulting from the permanent changes to the evaluation models.
Since the PCT values determined in the Large Break and Small Break LOCA analysis of record, which combined with all the PCT margin allocations, remain well below the 2200 OF regulatory limit, no reanalysis will be performed.
2700nc 9603270044 960319 PDR ADOCK 05000482 P Box 411/ Burhngton, KS 66839 / Phone (316) 364-8831 An Equa! Opportunity Employer McF/HC/ VET
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i WO 96-0047 Page 2 of 2 l
If you have any questions concerning this matter, please call me at (316) 364-8831, extension 4450, or Mr. Richard D. Flannigan at extension 4500.
Very truly yours, Otto L. Maynard OLM/jra Attachments cc:
L.
J.
Callan (NRC), w/a W.
D.
Johnson (NRC), w/a J.
F.
Ringwald (NRC), w/a j
J. C.
Stone (NRC), w/a i
_... _ _ = _ -
Attachment I to WO 96-0047 Page'1 of 2 P1 1
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i ATTACHMENT I i
CHANGES TO THE WESTINGHOUSE EMERGENCY CORE COOLING SYSTEM EVALUATION MODELS l
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Attcchment I to WO 96-0047 Page'2 of 2 l
l Changes To The Westinghouse j
Emergency Core Cooling System Evaluation Models i
Wolf Creek Nuclear Operating Corporation (WCNOC) has reviewed the annual 10 CFR 50.46 summary report of Emergency Core Cooling System (ECCS) Evaluation Model changes that were implemented by Westinghouse during 1995.
The report i
includes information concerning changes to and errors discovered in the evaluation models. The review concludes that the cumulative effect of changes to, or errors in the evaluation models on the limiting transient Peak Cladding i
Temperature (PCT) is not significant.
Therefore, reporting of the ECCS Evaluation Model changes may be submitted on an annual basis according to the reporting requirements set forth in 10 CFR 50.46 (a) (3) (ii).
Attachment II provides an update of PCT margin rack-up for Wolf Creek Generating Station (WCGS).
The PCT margin rack-up demonstrates that compliance with the requirements of 10 CFR 50.46 are maintained considering the combined effects of the ECCS Evaluation Model changes with the plant design changes performed under 10 CFR 50.59.
EVALUATION MODEL CHANGES In addition to the significant change associated with the power shape assumption for the large break LOCA evaluation model, which was previously reported in WCNOC to NRC letter ET 95-0096, dated September 9, 1995, there was J
only one other model change in 1995 meeting the reporting criteria of 10 CFR 50.46.
This is the NOTRUMP Specific Enthalpy Error discussed below.
NOTRUMP SPECIFIC ENTHALPY ERROR
Background
A typographical error was found in a line of coding in the NOTRUMP code. This line of coding was intended to model the calculation found in Equation L-127 of WCAP-1007 9-P-A.
Although the equation in the topical report is correct, the coding 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 correction is a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.
Affected Evaluation Model 1985 Westinghouse Small Break LOCA Evaluation Model Using NOTRUMP Estimated Effect 0
.tepresentative plant calculations have led to an estimated effect of +20 F for this error correction.
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I Attachtnent II to WO 96-0047 Pagd 1 of 3
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1 ATTACHMENT II ECCS EVALUATION MODEL PCT MARGIN ASSESSMENTS l
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Attachment II to WO 96-0047 Page 2 of 3 Large Break LOCA PCT Margin Rack-Up Summary A. ANALYSIS OF RECORD (1)
Evaluation Model:
1981 EM with BASH Peaking Factor:
FQT=2.50, FdH-1.65 SG Tube Plugging:
10%
Power Level / Fuel:
3565MW /17x17 V5H w/IFM, non-IFBA t
Limiting transient:
Cp=0.4, Min. Safeguards, Reduced Tavg 0
Peak Cladding Temperature (PCT):
1916 F 0
B.
PRIOR PERMANENT ECCS MODEL ASSESSMENTS APCT =
-31 F C. 10 CFR 50.59 EVALUATION 0
- 1. RCS Loose Parts APCT =
+20.2 F D.
1995 10 CFR 50.46 MODEL ASSESSMENTS (Permanent Assessment of PCT Margin) 0
- 1. Skewed Power Shape Penalty APCT = +152 F 0
- 2. Hot Leg Nozzle Gap Benefit APCT = -136 F l
0 E. TEMPORARY USE OF PCT MARGIN APCT =
0F F. OTHER MARGIN ALLOCATIONS
+50 F(2) 0
- 1. Transition Core (STD/V5H)
APCT =
0 I3) 2.
Cold Leg Streaming Temperature gradient APCT =
1971.20F Notes:
(1) Based on the reanalysis that was performed to support the Wolf Creek Power Rerate Program.
(2) Transition core penalty applies on a cycle-specific basis for reloads utilizing both V5H (with IFMs) and STD fuel until a full core of V5H is achieved.
0 (3) A PCT benefit of < 2.5 F was assessed and will be tracked for reporting purposes.
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l Attachment II to WO 96-0047 Page 3 of 3 1
l Small Break LOCA PCT Margin Rack-Up Summary A. ANALYSIS OF RECORDIII Evaluation Model:
1985-EM with NOTRUMP i
Peaking Factor:
FQ=2.50, FdH-1.65
)
SG Tube Plugging:
10%
Power Level / Fuel:
3565MW /17x17 V5H w/IFM, t
Limiting transient:
3-inch Break 0
Peak Cladding Temperature (PCT) :
1510 F 4
0 B.
PRIOR PERMANENT ECCS APCT =
+9 F MODEL ASSESSMENTS C. 10 CFR 50.59 EVALUATION 0
1.
RCS Loose Parts APCT =
+44.6 F D. 1995 10 CFR 50.46 MODEL ASSESSMENTS (Permanent Assessment of PCT Margin) 0
- 1. NOTRUMP Specific Enthalpy Error APCT =
+20 F 0
E. TEMPORARY USE OF PCT MARGIN APCT =
0F F. OTHER MARGIN ALLOCATIONS 0
1.
Cold Leg Streaming Temperature APCT =
+7 F Gradient 0
NET PCT Result 1590.6 F Notes:
(1) Based on the reanalysis that was performed to support the Wolf Creek Power Rerate Program.