ML19317D794
| ML19317D794 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 11/10/1976 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML19317D788 | List: |
| References | |
| RO-269-76-16, NUDOCS 7912100543 | |
| Download: ML19317D794 (2) | |
Text
_-_.-
c DUKE POWEP. COMPANY
~'
OCONEE UNZT 1 Report No.: R0-269/76-16 Report Date: November 10, 1976 4F occurrence Date: October 27, 1976 Facility:
Oconee Unit 1, Seneca, South Carolina j
Identification of Occurrence: Inadvertent power level increase above power level cutoff limit Conditions prior to occurrence:
Unit at 85% full power Description of Occurrence:
On October 27, 1976, Oconee Unit I was operating below the power level cutoff value of 92.5% full power while awaiting xenon react'ivity conditions as required by Oconee Technical Specifications 3.5.2.5.d to permit operation above this power level.
During the period, while reactor power was at 85%
full power, a feedwater heater which had previously been isolated due to a malfunction in the heater drain system was placed into service.
This resulted in a feedwater transient which caused a reactor power increase of approximately 8% full power.
The resulting power level of 93% full power exceeded the power icyc1 cutoff limit by approximately 0.5% full power.
The reactor operator promptly reduced reactor power at 15 MW/ minute to reduce reactor power below the power level cutoff limit. The reactor power decrease was stopped at 80 percent full power as unit conditions normalized.
Apparent Cause of Occurrence:
This occurrence was apparently caused by a faulty level indicator on the feedwater heater "D2" flash tank.
This prevented operation of heater drain valves, resulting in a high flash tank level and subsequently resulting in automatic isolation of the steam extraction of the "C" heaters due to a high level. When the flush tank was dumped to the condenser and the "C" heaters l
were placed back into service, a feedwater transient occurred, resulting in i
a reactor power increase above the power level cutoff limit.
Analysis of Occurrence:
l This occurrence resulted in a power level increase above the power level cutoff for a period of less than a minute.
At the time the xenon level was approaching its equilibrium value and the xenon worth was changing very slowly with time.
This very brief power escalation resulted in no signifi-cant xenon perturbation or apparent power peaking.
All control systems functioned as required.
It is concluded, therefore, that the health and l
safety of the public were not affected by this incident.
I Corrective Action:
A procedure change will be implemented by December 1, 1976 which will require reactor power to be reduced by a minimum of 10 percent below the power level l
cutoff when the reactor is in a transient xenon condition, prior to making high pressure heater extractions.
It is considered that no further corrective action is necessary.
Duxn POWER COMPANY Powza Brim No 422 horTn Curacu STattT.CnAnwrTE. N. C. us24a wuiw o
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November 10, 1976 T.C8=Ch g, An ga 704 vitt Fett Otut E
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3*3-4063 Mr. Norman C. Moseley, Director U. S. Nuclear Regulatory Commission Suite 818 230 Peachtree Street, Northwest Atlanta, Georgia 30303 Re: Oconee Unit 1 Locket No. 50-269
Dear Mr. Moseley:
Pursuant to Sections 6.2 and 6.6.2 of the Oconee Nuclear Station Technical Specifications, please find attached Reportable Occurrence Report R0-269/
76-16.
Very t'ruly yours, n
t) a _ d,
g i /*
'~
William O. Parker, Jr. Q j
EDB:ge Attachment I
i cc: Director, Office of Management Information and Program Control 4
l.
I I
i
,,,,_,._---._..c-
DUKE POWER COMPANY OCONEE UNIT 1 Report No.: RD-269/76-16 Report Date: November 10, 1976 Occurrence Date: October 27, 1976 Facility: Oconee Unit 1, Seneca, South Carolina Identification of Occurrence: Inadvertent power level increase above power level cutoff limit Conditions prior to Occurrence: Unit at 85% full power Description of Occurrence:
On October 27, 1976, Oconee Unit 1 was operating below the power level cutoff value of 92.5% full power while awaiting xenon reactivity conditions as required by Oconee Technical Specifications 3.5.2.5.d to permit operation above this power level.
During the period, while reactor power was at 85%
full power, a feedwater heater which had previously been isolated due to a malfunction in the heater drain system was placed inco service.
This resulted in a feedwater transient which caused a reactor power increase of approximately 8% full power.
The resulting power level of 93% full power exceeded the powcc level cutoff limit by approximately 0.5% full power.
The reactor operator promptly reduced reactor power at 15 MW/ minute to reduce rehetor power below the power level cutoff limit. The reactor power decrease was stopped at 80 perccht full power as unit conditions normalized.
Apparent Cause of Occurrence:
This occurrencc was apparently caused by a faulty level indicator on the feedwater heater "D2" flash tank. This prevented operation of heater drain valves, resulting in a high flash tank level and subsequently resulting in automatic isolation of the steam extraction of the "C" hesters due to a high level. When the flush tank was dumped to the condensar and the "C" heaters vere placed back into service, a feedwater transient occurred, resulting in a reactor power increase above the power level cutoff limit.
Analysis of Occurrence:
This occurrence resulted in a power level increase above the power level I
cutoff for a period of less than a minute.
At the time the xenon level was approaching its equilibrium value and the xenon worth was changing very i
slowly with time. This very brief power escalation resulted in no signifi-l cant xenon perturbation or apparent power peaking.
All control systems functioned as required.
It is concluded, therefore, that the health and safety of the public were not affected by this incident.
Corrective Action:
t A procedure change will be implemented by December 1, 1976 uhich will require reactor power to be reduced by a minimum of 10 percent below the power level cutoff when the reactor is in a transient xenon condition, prior to making high pressure heater extractions.
It is considered that no further corrective action is necessary.
,