ML19329A684
| ML19329A684 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 02/05/1973 |
| From: | Desiree Davis US ATOMIC ENERGY COMMISSION (AEC) |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8001090668 | |
| Download: ML19329A684 (1) | |
Text
5 1973 Docket Nos. 50-269/270/287-Note to Files CONSEQUENCES OF A CFT LINE BREAK ACCIDENT AT 5% POWER 2
From B&W's analysis of a 0.5 ft break (Oconee FSAR Supplement 13-56), an adiabatic heat up rate of approximately 14*F/sec is calculated for the time period between igg to 250 gec.
At 5% power the heat up rate would be 0.7 F/sec (14 F/sec x 0.05).
Decay heat might raise this 15% at 100 see and lower it by 30%
at 1000 sec. Using a constant 0.7"F/see would be conservative for the full period 100-1000 sec.
If one assumes a dry vessel with E0B at 100 sec (worst case-homogeneous system) and takes no credit for any CFT water injection after E0B, this would bound the problem in terms of minimum water remaining in the vessel and limiting the ECCS (no CFT water).
Duke has indicated (2/1/73 letter) that the operator can provide an additional 1500 gpm of LPI water in 900 sec (15 min).
Operational Safety (D. VanNeil) has reviewed this problem and have concluded that the operating staff at Oconee is sufficient j
to perform the required actions in 15 minutes.
If one assumes only one HPI pump until 900 sec and afterwwrds an additional 1500 gpa from the LPI pump, the bottom of the core is recovered at approximately 920 seconds. Based on a similar
.i reflood transient, the clad temperature will turn around in less than 30 seconds after bottom of core recovered.
In adiabatic heat up is assumed for the entire period from 100 seconds to clad turnaround at 950 seconds. From an initial temperatureof600to700Fatig0sec,theresultingmaximum clad temperature is 1100 to 1400 F.
At these temperatures, metal-water is essentially zero, the core geometry is still coolable and long term cooling is established.
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Donald K. Davis Pressurized Water Reactors Branch No. 4 Directorate of Licensing PWR-4 L:C/PWR-4
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