ML20024B418
| ML20024B418 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 09/19/1978 |
| From: | Nirodh Shah BABCOCK & WILCOX CO. |
| To: | Cartin L BABCOCK & WILCOX CO. |
| References | |
| TASK-06, TASK-07, TASK-6, TASK-7, TASK-GB GPU-2503, NUDOCS 8307080680 | |
| Download: ML20024B418 (2) | |
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THE BABCOCK & WILCOX COMPANY POWER GENERATION GROUP To l
j L.R. CARTIN. PLANT DESIGN i
from P. 7 N.H. SHAM. ECCS AllALYSIS (2136) 803 **3 3 y
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File No.
6 or Ref.
Date
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AUXILIARY FEEDWATER LEVEL CONTROL SCHEMES SEPTEMBER 19. 1978 h
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References:
1.
Memo, I..R. Carcin to Distribution, "A W Actuation and b.'
Control." September 7, 1978.
g-2.
Memo N.H., Shah to D.H. Roy, " Status of 205 FA Small
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Break LOCA Analysis," T3.4, March 30, 1978.
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Reference 1 presents two auxiliary feedvater (AW) actuation and concrol h
schemes. Thsse schemes are basically
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a.
Actuate and control AW to 40 feet at all times.-
b.
Actuate and control AW to 40 feet only when ES/AS is the initiator.
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As per the request made in reference 1, the impact assessment of the two N
[y-A W control scheme on LOCA analyses is given below.
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Large Break LOCA Analyses: The peak cladding temperature (PCT) will
?L-change by an insignificant value using either of the two A W control h..
scheme.
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b.
M&E Release: The peak building pressure and temperature will change
,4 by an insignificant value using either of the two control scheme.
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c.
Small Break LOCA Analysis: (1) Scheme A The NRC approved small
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break analyses (BAW-1074A) of S&W's 205 FA plants were done using a scratch 40 f t AW level control and a simple primary to secondary SG heat transfer model. The Scheme A level control with a more proper p.
j SG heat transfer model vill have a negative irpact for certain small breaks. Although the overall results are expected to be in compli-i ance with the ECCS acceptance criteria, a cure uncovery may occur for certain breaks and will thus change the peak cladding temperature by 20"F.
Acceptability of the control scheme vill require at least one CRAFT computer analysis for which the required budget is 300 snhours J
l and 8 computer hours.
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4 N.H. Shah to L.R. Carti's Page Two Subi: Auxiliary Feed.ater Level Control Sche =es Scote=ber 19, 1978 Schene B: The drawbacks of Scheme A are inherent in Scheme 3. (i.e., the core may not reclain covered for certain s=all breaks. Further= ore,.a small break
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analysis of reference 2, 0.05 ft2 at pu=p discharge, showed that the RC pres-sure did not get low enough to actuate the ESTAS. Rather, the ESTAS actuates on high contain=ent building pressure of 4 psig. It is possible that for a smaller break sise, the fan coolers and the passive heat sinks may not allow the containment pressure to increase to 4 psig fast enough for a timely ESTAS l
actastion. Without the timely ESTAS, the ECCS system would be unable to keep the core coolable. The minimum resources required to justify the control i
scheme is 500 canhours and 8.5 cocputer hours, which includes CONTEMPT code analyses for building pressure and a CRAFT code analysis for the core safety.
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Note: The analyses scope identified for the two schemes are for an in-house 2
acceptance of the schemes. If core uncovery is calculated for the
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smaller breaks a new licensing calculation may be necessary.
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