ML19329A210
| ML19329A210 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 08/04/1976 |
| From: | Zech G Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7912300251 | |
| Download: ML19329A210 (4) | |
Text
f '_ -t-G i
/
Meeting Summary for Duk2 Power August 4, 1976 cc:
Licensee B. Grimes NRC PDR G. Knighton Local PDR B. Youngblood B. Rusche W. Regan E. Case D. Bunch J. Collins R. Boyd R. Heinemat W. Kreger R. Ballard V. Stello
- 11. Denton M. Spangler D. Skovholt J. Stepp R. Denise L. !!ulman R. DeYoung T. Carter OR PM R. Maccary D. Ross S. Sheppard j
R. Tedesco R. Fralcy, ACRS(16)
I K. Goller OIGE(3)
D. Eisenhut OELD V. Moore Principal Staff Participants R. Vollmer M. Ernst bec:
T. B. Abernathy, TIC W. Gammili J. R. Buchanan, NSIC P. Collins C. lle1temes R. Ilouston T. Speis R. Clark J. Stolz K. Kniel O. Parr W. Butler D. Vassallo J. Knight S. Pcwlicki I. Sihweil P. Check T. Novak Z. Rosztoczy V. Benaroya G. Lainas T. Ippolito D. Zicmann G. Lear R. Reid L. Shao R. Baer A. Schwencer i
I i
7312300 k$I.
1 wew i
^
[
4, UNITED STATES y
- t NUCLEAR REGULATORY COMMISSION 3
i
. l WASHINCTON, D. C. 20555
"\\,...../
DOCKET NOS.: 50-g/270/287 DATE: Augus t 4, 1976 LICENSEE:
Duke Power Company (DPC)
FACILITY:
Oconee Units 1, 2 and 3
SUMMARY
OF MEETING HELD ON JULY 8,1976, TO DISCUSS PWR REACTOR VESSEL OVERPRESSURIZATION EVENTS On July 8,1976, representatives of DPC met with the NRC staff to discuss reported instances of reactor vessel overpressurization at various PWR facilities and to discuss specific methods employed at the Oconee facilities to prevent similar occurrences.
f A list of attendees is enclosed.
i Significant discussions / agreements are summarized below.
The staff provided a sumary of the 26 instances of reported reactor vessel overpressurization which have occurred in PWR facilities over the past four years.
of plant conditions at the time of each event, the causes whichIncl contributed to the overpressurization and its magnitude relative to 10 CFR Part 50, Appendix G criteria. The staff indicated the need for interim and long term fixes to prevent any similar occurrences in the future.
The licensee provided a description of their experience at the Oconee Station and stated that they have reduced the problem of reactor vessel overpressurizations to a low probability.
avoiding water solid conditions by requiring that either a steam bubbleT or a nitrogen blanket be maintained in the pressurizer when the reactor coolant system is at lower temperatures and pressures.
In addition, the licensee indicated that pressurizer power operated relief valve design includes a dual setpoint to provide over pressure protection both at normal operating conditions and while shutdown.
550 psig provides NDT protection.
The lower setpoint of The licensee described the pressurizer Nitrogen Blanketing System as occuppying approximately one-half of the pressurizer volume with the pressure normally maintained between 30 and 45 psig.
difficulities have been attributible to the nigrogen blanket.No operating The I
s I
a a
^
F
- August 4, 1976 pressurizer power operated relief valve design consists of a low range (0-600 psig) band and a high range (0-2500 psig) band thich is selected by the operator. Separate pressure transmitters ?rovide an input for each band into the relief valve control circuitry.
When a unit is being shut down, the low range pressure transmitter is valved in at < 600 psig and the operator selects the low setpoint (550 psig) when Ihe reactor coolant system pressure is < 500 psig and temperature is < 275 F.
The licensee indicated that the volume of the nitrogen blanket would provide approximately 12-15 minutes before water solid conditions would be reached in the pressurizer for the worst-case event reviewed involving the HP injection pumps. The licensee also indicated that the volume if the Letdown Storage Tank which supplies the HP injection pumps is not great enough to fill the pressurizer, therefore, this particular accident could not occur during normal shutdown conditions.
The staff indicated that they would review the system diagrams, control logics and operating procedures provided by the licensee and would contact the licensee'should additional information be required or to identify any future action that may be found necessary.
Gary G. Zech, Project Manager Operating Reactors Branch #1 Division of Operating Reactors
Enclosure:
List of Attendees cc w/ encl:
See next page s
I I
l sw A s l
l
f' 1
_NRC STAFF MEETING WITH DUKE POWER COMPANY JULY 8, 1976 NRC DPC G. Lanik D. Holt A. Schwencer T. Crawford i
J. Slider M. Tuckman
-G.
Manz E. Blakeman R. Gamble E. Gottfried Babcock & Wilcox
- 0. Parr R. Fluegge W. Keyworth
.R. Baer R. Klecker C. Berlinger T. Novak V. Stello G. Zech e
-i i
- >f}