ML20198C659
| ML20198C659 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 10/23/1985 |
| From: | Nix H GEORGIA POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 50-321-1985-3, 50-321-85-03, 50-321-85-3, LR-MGR-067-1085, LR-MGR-67-1085, NUDOCS 8511120140 | |
| Download: ML20198C659 (3) | |
Text
r Georgia Power Company Post Offica Ccx 439 B31:y, Georcis 31513 Telephone 912 367-7781 912 537-9444 05 cc737 g GeorgiaPbwer
.h Edwin 1. Hatch Nuclear Plant October 23, 1985 LR-MGR-067-1085 PLANT E.
I. HATCH Special Report Docket No. 50-321 United States Nuclear Regulatory Commission Office of Inspection and Enforcement Region II Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323 ATTENTION:
Dr. J. Nelson Grace Attached is Special Report No.
50-321/1985-003.
This report is required by Unit 2 Technical Specifications section 3.3.6.2, ACTION: a.
4Y/M fH. C.
Nix
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l General Manager HCN/SBT/ImW xc: Document Control Letter File (2) l l
l 8511120140 851023 PDR ADOCK 03000321 S
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l Special Report 50-321/1985-003 This special report is required by Hatch Unit 2
Technical Specifications section 3.3.6.2, ACTION:
a.
because the seismic monitoring instruments listed below were inoperable for more than 30 days.
On 09/13/85 at approximately 1300 CDT, Unit 1 was in steady state operation at 2436 MWt (approximately 100% power) and Unit 2 was in steady state operation at 2436 MWt (approximately 100% power).
At that
- time, plant personnel were performing the monthly
" SEISMIC INSTRUMENTATION FT &
C" procedure for plant seismic instruments when they noted the following problems with seismic acceleration recorders lL51-R600A and lL51-R600B:
a.
the negative 12-volt power supply was reading approximately negative 2 volts, and b.
the positive 12-volt power supply was reading approximately positive 10 volts.
As a result of these voltage readings, plant personnel started trouble shooting the instrument loop.
The most likely cause of the voltage readings was a bad voltage control oscillator board.
While plant personnel were trouble shooting the system, a power surge occurred (cause unknown) resulting in the failure of the following:
a.
seismic acceleration recorders lL51-R600A and IL51-R600B.
b.
accelerographs required by item 1
of Tech.
- Specs, table 3.3.6.2-1 (these provide some of the inputs to recorders lL51-R600A and lL51-R600B):
1.
Unit 2
diesel generator building elevation 130 feet (2L51-N021).
2.
Unit 2 reactor building 187 feet level on the drywell pedestal (2L51-NO20).
3.
Unit 2 drywell - feedwater inlet to the Reactor Pressure vessel (2L51-N004).
4.
Unit 1 and Unit 2 switchyard (lL51-N005).
c.
instruments which are not required by Tech.
Specs.
(these provide the remaining inputs to recorders 1L51-R600A and 1L51-R600B):
1.
Accelerograph lL51-N002.
2.
Accelerograph lL51-N003.
w>
Consequently, no seismic monitoring capability is operable for the areas required by item 1 of Tech. Specs.
table 3.3.6.2-1.
Seismic monitoring instrumentation is available for the remainder of tra Tech.
Specs. required areas (i.e.,
items 2,
3, and 4 of Tech. Specs. table 3.3.6.2-1).
The failure of the afore-mentioned instrumentation will not adversely affect plant safety because:
a.
The failed instrumentation provides no trip functions.
b.
The remaining, operable instrumentation provides sufficient diverse seismic monitoring capability.
Seismic acceleration recorders lL51-R600A and IL51-R600B have been repaired; however, the accelerographs which provide the inputs to them are still inoperable.
Replacement accelerographs are no 1.onger manufactured.
Design change requests which will authorize installation of an improved model are presently in the design change approval process.
When the design change is approved, the failed accelerographs will be replaced, with the exception of 2L51-N004, which is located inside the Unit 2
drywell.
2 L51-N004 will be replaced at the next scheduled outage (following deLign approval) which is of sufficient duration to permit personnel entry.