ML19322B525
| ML19322B525 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/15/1974 |
| From: | Thies A DUKE POWER CO. |
| To: | Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML19322B522 | List: |
| References | |
| NUDOCS 7912040555 | |
| Download: ML19322B525 (4) | |
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! JUKE POWER COMPANY Powra Bust.orwo 422 Sourn Cuuncu StazzT, CnAntoTTE, N. C. menos A. C. T) r.s se.
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March 15, 1974 Mr.. Norman C. Moseley, Director Directorate of Regulatory Operations-U. S. Atomic Energy Commission Region II - Suite 818 230 Peachtree Street, Northwest Atlanta, Georgia 30303 Re:
RO:II:FJ 50-269/74-1
Dear Mr. Moseley:
Please find attached our response to Items 1.A.b and I.A.c listed in R0 Inspection Report 50-269/74-1.
Duke Power Company does not consider any information contained in RO Inspection Report 50-269/74-1 to be proprietary.
Very/ truly yours, 1
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I DUKE POWER COMPA!'Y e
OCONEE UNIT 1 REFPONSE TO RO IKSPECTION REPORT 50-269/74-1
- 1. /.. b.
Inco niete Powcr Runback Followinn a Failed Rod When the runhack occurred on November 20, 1973, the operator brought the 1
power level as indicated by core delta temperature to less than 60 percent of rated power as required by Technical Specification 3.5.2.2c.
The operator did not reduce the unit load to less than 55 percent full power as required by EP/0/A/1000/21, " Inoperable Control Rod."
The requirement in EP/0/A/1800/21 to reduce unit power to 55 percent when a control rod is inoperable was a self-imposed reduction of 5 percent below the i
power level requirements of the technical specifications.
It was intended to provide marr,in to prevent violations of technical specifications.
At tne present time, the station operations group has initiated a complete review of proccAures which contain operational 11mits more restrictive than those contained in the technical specifications. Uhere these operational limits exist, they will be re-identified as guides for the operator or they will be changed to i
limits which are more compatible with the~ technical specifications.
In addition, the necessity of following operating and emergency procedures has been emphasized to operations supervisors at shift supervisors meetings and in a memorandur issued on January 29, 1974 by the opcrating Engineer.
7.A.c.
P(thdrnwc1 of Rods Durino nn Unscheduled Power Reduction When the poi.'er runback was initiated on November 20, 1973 because of a dropped control rod, the pressuricer spray valve opened to maintain reactor coolant system pressure.
When pressure stabilized, the spray valve was given a close signal by the control system but did not respond.
Consequently, reactor coolant syctcu pressure continued to decrease. As pressure decreased, attempts were made to close the pressurizer spray valve and block valve by remote manw:1 action to secure the pressurizer spray, but these attempts were unsuccessful.
As reactor coolant system pressure neared the low pressure trip point, the control operator momentarily withdrew control rods to halt the pressure decrease. A plot of reactor power during this period showed that power increased less than 1 percent from 55 percent full power.
This change in reactor power was insignificant, and the operator and an Assistant Operating j
Engineer who was in the control room at the time of the power reduction had full knowledge of the event that had led to the power reduction.
In the limits and precautions section of operating procedure OP/1/A/1102/04,
" Operation at Power," it is stated that in the event of an unscheduled power reduction, the power level shall not be increased.unt11 an investigation has been conducted and any necessary corrective action taken.
In the incident cited in this inspection report, the operator and Assistant Operating Engineer were fully knowledgea,ble of the plant conditions that had led to the power
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q runback, and corrective action was being taken to close the pressuricer spray block valve to halt pressuriner spray and thus prevent further decrease in
, system pressure.
The operator withdrew rods to gain more time to close the block valv2.
As stated in the "Stcan Production Department Administrative Policy Manual for Operational Quality Assurance of Nucicar Stations," written procedures cannot address all contingencies, and therefore, should contain a degree of flexibility appropriate to the activities for which cach is applicable.
Tiic precaution in the procedure for operation at power was not intended to preclude operator action required to stabilize plant conditions, especially as in this incident, when such action was taken with full knowledge of the, cause of the transient and uithin the flexibility permit'ted by procedures.
Such action also precluded an unnecessary trip from low reactor coolant r.ystem pressure and unnecessary injection of borated water.
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e Letter to Duke Power Company from N. C. Moseley dated APR ] 91974 50-269/74-1 Letter from Duke Power Company, A. C. Thies, dated March 15, 1974 I
DISTRIBUTION:
H. D. Thornburg, RO RO:HQ (4)
Directorate of Licensing (4)
]_., u-" "--TR Central Files cc encl. only:
PDR Local PDR NSIC DTIE, OR State I
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