ML17317B052
| ML17317B052 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 03/21/1979 |
| From: | Shaller D INDIANA MICHIGAN POWER CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| SI-03, SI-3, NUDOCS 7904040146 | |
| Download: ML17317B052 (6) | |
Text
SUBJECT!
FORWARDS 790106 SAFETY INJECTION ACTUATION (SPECIAL REPT SI 03)
~ STKAM LINE PRESSURES INDICATED HIGH ~ CAUSED BY FROZEN STEAM PRKSSURE INDICATION LINES FORCING INDICATED PRESSURE 100 PSI GREATER THAN OTHER STEAM PRESSURE,lINDICATIONS DISTRIBUTION CODE!
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P.O. Box 458, Bridgman, michigan 49106 March 21, 1979 Mr. J.
G. Keppler, Regional Director Office of Inspection and Enforcement United States Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 Operating License DPR-74 Docket No. 50-316 Special Report:
SI-03
Dear Mr. Keppler:
The purpose of this letter is to forward to you the attached Special Reports required by Appendix A Technical Specification 3.5.2, Emergency Core Cooling Subsystems.
Sincerely, D. V. Shaller Plant Manager
/mkm cc:
J.
E.
Dolan R.
M. Jurgensen R.
F. Kroeger R. J. Vollen BPI K.
R. Baker RO: III RE C. Callen MPSC P.
M. Steketee, Esq.
R. Malsh, Esq.
M.
H. Judkis PNSRC J.
F. Stietzel R.
S.
Lease
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0 INDIANA AND MICHIGAN POWER COMPANY DONALD C.
COOK NUCLEAR PLANT Opera ting Licens e DPR-74 Docket No. 50-316 Special Report:
SI-03 SAFETY INJECTION ACTUATION - JANUARY 6, 1979 CONDITIONS PRIOR TO OCCURRENCE The Reactor was in operational Mode 1 at 1005 steady state power.
Control Rods were in the manual mode of operation.
Steam Generator level controls and Pressurizer Pressure and level controls were in the automatic mode of control and functioning properly.
All Control Rods were fully withdrawn except Control Bank "D" which was at 217 steps.
Reactor Coolant System Boron Concentration was 674 PPM.
DESCRIPTION OF OCCURRENCE Steam Line Pressures from 82 and 5'3 Steam Generators started indicating high.
While the Steam Lines, Steam Generator Stop Valves, and Pressure Sensing Lines are in an enclosure, the enclosure is designed with vents and blow-out panels in case of Steam Line rupture.
Outside air temperature was -6oF.
With these two pressure indications increasing and all other parameters
- constant, the analysis was that these two sensing lines were freezing up and steps were being taken to thaw them out.
Before thaw-out could be accomplished, the two frozen li'nes increased pressure to the Transmitters and Reactor Protection by 100 psi greater than a normal operating Steam Line Pressure.
DESIGNATION OF CAUSE OF OCCURRENCE The two frozen Steam Pressure Indication Lines forced the indicated pressure 100 psi greater than the other steam pressure indications.
This allowed the 100 psi high Steam Line Differential on 2/3 Pressure Channels on 1/4 Steam Generators Logic to complete and safety injection was actuated as designed.
ANALYSIS OF OCCURRENCE The following is a list of major items that were reviewed for their safety injec-tions:
(a)
Reactor Coolant S stem Cooldown Rate The cooldown rate was an almost instantaneous drop on Tavg from 573oF to 540oF due to the Reactor-Turbine trip and actuation of the Steam Dump System.
The rapid cooldown was terminated when the Steam Dump Valves were automatically tripped closed when Lo-Lo Tavg of 541oF was reached.
The overall cooldown rate was similar to that experienced during a Reactor trip without safety injection.
Operating License DPR-74 Docket No. 50-316 Special Report:
SI-03 Page (2)
(b)
Thermal Effects of Safet In 'ection During this occurrence the Centrifugal Charging Pumps injected to the Reactor through the safety injection path for 'approximately 14 minutes.
During this time approximately 4,200 gallons of borated water with an initial temperature of 165oF was injected.
This is the third inadver-tant safety injection in which water was injected into the Reactor Coolant System and conservatively would constitute less than 3.2/10,000 of allowable cycles'.
'The total accumulated cycles to date are 6.5/10,000.
(c)
Effects on the Emer enc Core Coolin S stem Pi in ECCS The piping and supports in the ECCS were given a thorough visual inspec-tion to determine if any mechanical damage was experienced during the safety injection.
There was no evidence of any mechanical damage or abnormal movements of the piping.
CORRECTIVE ACTIONS The frozen Pressure Sensing Lines were thawed..
Some vents in the enclosure that were open to the outside were sealed over with plastic film.
The Plant has' winterizing checklist and these vents have been added to this list to prevent reoccurrence.