ML19221A139
| ML19221A139 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/04/1979 |
| From: | Case E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| References | |
| NUDOCS 7905190192 | |
| Download: ML19221A139 (3) | |
Text
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April 4,1979 PRELIMINARY g
g CHRONOLOGY OF TMI-2 3/28/79 ArcIDENT UNTIL CORE COOLING REST 0h:3 pp g
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TIME ( Approximate)
EVENT about 4 AM t.oss of Condensate Pump (t = 0)
Loss of Feedsater Turbine Trip t = 3-6 sec.
Electrcmatic relief valve opens (2255 psi) to relieve pressure in RC5 t = 9-12 sec.
Reactor trip cn high RCS pressure (2355 psi) t = 12-15 sec.
RCS pressure decays to 2205 psi (relief valve shouy have closed) t - 15 sec.
RCs hot leg temperature peaks at 611oF, 2147 PSIG (450 psi over saturation) t - 30 sec.
All three auxiliary feedwater pumps running at pressure (Pum started at turbine trip)ps 2A and 2B No flow was injected since discharge valves were c @ closed, t = 50 sec.
Pressurizer level indication begins to rise rapidly t = 1 min.
Steam Generators A and B secondary level very low - drying out over next couple of minutes, t = 2 min.
ECCS initiation (HPI) at 1600 psi t 11 min.
Pressurizer level off scale - high -
one HPI pump manually tripped at about 4 min, 30 sec.
Second pump tripped at about 10 min. 30 sec.
te 6 if n.
RCS flashes as pressure bottoms out at 1350 psi (Hod leg temperature of S84cF) t = 7 min., 30 sec.
Reactor building sump pump came on.
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134 20i' 290s19M?
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. TIME EVENT t = 8 min.
Auxiliary feedwa ter flow is initiated by opening closed valves t = 8 min. 18 sec.
Steam Generator B pressure reached minimum t = 8 min. 21 sec.
Steam Generator A pressure starts to recover t = 11-12 min.
Makeup Pump (ECCS HPI flow) restarted by operators t = 11 min.
Pressurizer level indicatior, comes back on scale t = 15 min.
RC Drain / Quench Tank rupture disk blows at 190 psig (setpoint 200 psig) due to continued discharge of electromagnetic relief valve t = 20 - 60 min.
System parameters stabilized in saturation condition at about 1015 psig and about 5500F t = 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, 15 min.
Operator trips RC pumps in Loop B.
t = 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, 40 min.
Operator trips RC pumps in Loop A t = l-3/4 - 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> CORE BEGINS HEAT UP TRAN5IENT - Hot leg temperature begins to rise to 6200F (off scale within 15 minutes) and cold leg temperature drops to 1500F (HPI water) t = 2.3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> Electromatic Relief Valve isolated by operator af ter 5.G.-B isolated to prevent leakage t = 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> RCS pressure increases to 2150 psi and' electromatic relief valv? opened t = 3.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> RC Drain Tank pressure spike of 5 psi t = 3.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> RC Drain tank pressure spike of 11 psi RCS pressure 1750; Containment pressure increases from 1 to 3 psi t = 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Peak containment pressure of 4.5 psig.
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t = 5 - 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> RCS pressure increased from 1250 psi to 2100 pst 134 202 a
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TIME EVENT t = 7.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Operator opens electromatic relief valve to depressurize RCS to attempt initiation of RHR at 400 psi t = 8 - 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> RCS pressure decreases to about 500 psi CFT.nartial discharge t - 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> 28 psi containment pressure spike, containment sprays initiated and stopped after 5000 gal, of NaOH i.njected (about 2 minutes of operation) t = 13.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Electromatic relief valve closed to
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repressurize RCS, collapse voids, and start RC punip te 13.5 - 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> RCS pressure increased from 650 psi to 2300 psi t = 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> RC pump in loop A started., hot leg temperature decreases 'to 5600F, and cold leg temperature increases to 4000F indicating flow through steem generator Thereafter 5/G "A" steaming to condensor Condensor vacuum re-established RCS cooled to about 2800F,1000 psi Now (4/4)
High radiation in containment Some core damage All fuel in core therr.iocouples < t750F Using Vent Valve with small makeup flow Slow cooldown R8 pressure negative G
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