ML19308C347
| ML19308C347 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/16/1978 |
| From: | Hilbish J METROPOLITAN EDISON CO. |
| To: | Geoffrey Miller, Seelinger J METROPOLITAN EDISON CO. |
| References | |
| TASK-TF, TASK-TMR NUDOCS 8001220794 | |
| Download: ML19308C347 (3) | |
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METROPOLITAN EDISON C O M P A N Y soo,.oi.,y o, a.o.,.i rooii vi,nii., co,no,...oo subject Reactor Trip / Safety Injection 11-07-78 Location Till Nuclear Station Middletown, PA 17057 Date November 16, 1978 To G.P. Miller J.L. Seelinger
Enclosure:
Subject Report The report of the reactor trip of 11-07-78 is forwarded for your information.
J.. Hilbish Station Nuclear Engineer JFH:bil cc: J.J._Barton G.R. Hitz W.H. Zewe (M. L.._ Bed R.M. Klingaman I.D. Porter R.W. Bensel G.A. Kunder R.P. Warren M.L. Benson L.C. Lanese J.B. Logan T.G. Broughton L.L. Lawyer J.A. Brummer B.A. Mehler J.J. Chwastyk W.E. Potts R.C. Cutler L.C. Rogers W. J._F_
M.J. Ross
JTR'. Fl oy~d, D.M. Shovlin J.G Diefbein B.G. Smith R.W. Heward
.J._Toole__
J.F. Hilbish G.J.Troffep INTER-OFFICE MEMORANDUM p'
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N SECTI0il 1 SYtt0PSIS OF EVEtiT At 0524:49 on November 7, 1978, TMI-2 experienced a reactor trip during a power runback from 92% rated thermal power.
Prior to the reactor trip, testing per TP 800-05 Reactivity Coefficients at power was in progress. All operating parameters were normal except for RC Tave which had been elevated to 5880 0
(6 F above normal) for temp-erature coefficient measurement.
Initial system operating conditions are listed in Section 4.
At 0523:37, a heater drain tank low level alarm was received. This auto-matically tripped operating heater drain pumps HDPIA and 18.which normally supply approximately 30% of the total feedwater flow to the suction of the feedwater pumps. The feedwater pumps tried to meet the increased feedwater demand, however Condensate Booster pump COP 2C tripped on low suction pressure.
This automatically tripped FWP18.
The Integrated Control System began a power runback to 55% rated thermal power based on the loss of one feedwater pump, however, due to the elevated Reactor Coolant System temperature required by the testing in progress, the reactor tripoed at 64% power prior to completion of the power runback, as all four RPS channels received a variable temperature pressure trip signal. At this point, the operator secured letdown flow (closed MUV376). A second makeup pump was started prior to the safety injection.
Reactor coolant system pressure continued to decrease and safety injection was automatically initiated at 1600 psig thus limiting the pressure decrease to 1550 psig at twenty-five. seconds after the reactor trip. The decreased RC System volume due to the cooldown and depressurization caused the pressurizer volume to decrease below zero indicated level for approximately 30 seconds, however calculations shown in Appendix A support that the pressurizer was not emptied during the transient.
s As reactor coolant system pressure recovered, the operator noted that the A OTSG secondary pressure was still decreasing, showing evidence of a steam leak on the A OTSG. Attempts were made to isolate possible sources of a steam leak.
A side secondary system pressure decreased to 543 psig and began to recover approximately 12 minutes af ter the reactor trip. A sequence of events is pre-sented in Section 5.
o SECTION'3 ACTION 1.
Insure BWST low level switch are properly reset - Provide more adequate surveillance, procedural guidance and/or contact status in the control room.
2.
Repair A turbine bypass valve found to be inoperable after the tran-sient which is the only identified cause of steam leakage on the A side.
N
/ 3.
This transient should be included in operating training, so that all
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operators review the sequence and consequences of this transient. The effect on the transient of the momentum of the runback leading into the reactor trip should be stressed.
'4.
Include more specific guidance for the control room operators during the shift briefings when~ start-up testing requires special operating conditions such as elevated Tiv - Effects of the special operating conditions and consequences of these conditions during transients should be considered, h
y ( 5.
By use of Retran computer modeling, determine the possible effects of h 1a increasing the normal operating pressurizer level above 220", to preclude
\\P / # [f draining pressurizer below indicated zero level during this type of tran-V' 4p
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sient.
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.1/6. Compare results of actual plant response to results of GPUSC RETRAN flodel
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for primary and secondary system response.
7.
Revise computer inputs of make-up pump status during pump start and pump trip.
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