ML19208C054
| ML19208C054 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/17/1979 |
| From: | Rebecca Stone OAK RIDGE NATIONAL LABORATORY |
| To: | |
| Shared Package | |
| ML19208C045 | List: |
| References | |
| NUDOCS 7909240469 | |
| Download: ML19208C054 (2) | |
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Enclosure S t
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Three Mile Island - 2 Technical Support Ir Natural Circulation R. S. Stone l
J Prob 1cm:
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g Will the core oc cooled adequately by natural circulation should i
all coolant circulation pumps become inoperable?
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Description o f.'.'ork Performe.1:
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The objective was to extrapolate fror fuel temperatures then
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being measured and so predict the temperatures to be expected if the core cooling was limited to natural convcction.
Working from dimensions in the TMI PSA.-:, the net buoyant driving force available as a result of heating in the core and cooling in the heat exchanger were calculated t.ru This was th'en equated to the frictional resistance to derive the flow rate and to deter:-ine the differential temperature necessary to close the loop.
At TMI conditions a day and a half after shutdown, assuming the react or I
core power then to be 10 Mw, the anticipated differential temperature g
across the core was calculated to be 54.3*F.
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This is a manageable temperature rise.
With an intact core and g
an operational heat exchanger there should be no problem running on t
l natural convection cooling at the 10 Mw level.
The concern is that the core may not be intact.
At the time of the analysis, thermocouples in one corner were indicating temperatures well above those of the rest of the core.
The fear of course was that the high temperature region had blockage and restricted flow.
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Additional calculations were then made based on an assumption of k.
h quarter-core blockage.
These calculations indicated the core temperaturc j
rise with natural circulation at 10 bhv could be as high as 331*F.
This
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would produce boiling in the damaged quadrant for any inlet temperature.
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Conclusions and Results:
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y Since the region she:ing elevated outlet temperature seemed to shift I
with changes in the eSice of eco.12nt p p, the asst p-in.) th:tt part of the core is obstructed has been less defensible.
If the cause is simply inertial channeling, there should be no problem under natural convection.
L Even if part of the core were obstructed to the extent calculated, the differential temperature will be proportional to power level.
At a month after snutdo::n, if we ass =0 2 W afterheat, the temperature rise would be 66.2*F, a level which could be tolerated.
There should be some concern over accuracy of temperature rise in the hot spot region.
As better measurements of temperature and flow benme available the above numbers would have to be modified; the methodology should be OK.
Work Requested Bv-NRC Bethesda (Hanauer, Buhl).
l Resu)3s Reported To:
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Same. Approximately April 8.
6 Work Performed By:
R. S. Stone, Bob Hedrick (SAI), Ted Mott (TEC).
Estimated Cost:
8 Mandt.ys, $2,640.
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