ML20055G878
| ML20055G878 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/19/1990 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 C311-90-2085, NUDOCS 9007240267 | |
| Download: ML20055G878 (2) | |
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OPU Nuclear Corporation gp-Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
July 19, 1990 C311-90-2085 U.S. Nuclear Regulatory Commission Attn: Document Control Desk:
j Washington,'D.C.
20555.
m Gentlemen:
Three Mile Island Nuclear Generating Station, Unit 1 (TMI-1)
Operating License No. OPR-50 Docket No. 50-289 Regulatory Guide 1.97 Compliance Containment High Range Radiation Monitors NRC Region 1 conducted an inspection-of the TMI-1 implementation program for, Regulatory Guide 1.97 requirements from May 7, 1990 to May 11, 1990.
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potential violation was identified at the inspection exit meeting involving' l
h lack of required physical separation between. the redundant, Class 1E'120 i
0 9 VAC power source cables for the-Containment High Range Radiation Monitors (RMG-22/23) routed.inside Control Room Panel PRF.
Subsequent.GPUN
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evaluation and walkdown of the affected cable routings, indicated that
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~l separation in accordance with GPUN System Design Description-(SDD) 772-A,
,TM1-1 Nuclear Generating Station Electrical Cable and Raceway. Routing, is Lalso not,provided between the Control Room Panel PRF and the Distribution
' Panels-as the power cables from redundant inverters to the monitors are
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- routed as non-safety related cables and sbere : ::a. non cable tray for i
approximately 20 feet in the Control-Building Relay Room. A separate l
review ^ identified that the Class 1E recorder output from the ratemeters was
- going to a non-class 1E recorder and was not properly isolated.
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The TMI-1 Containment High Range Radiation Monitors (RMG 22/23) are j
,4 Regulatory Guide l'.97, Category 1 instruments.
Accordingly, physicai separation of the power cables as specified by SDD 772-A, and the required J>
' isolation' will be:provided to satisfy Regulatory Guide 1.97 Category 1 l
7 requirements. The above modifications' to provide physical separation and isolation are being evaluated for potential implementation during the upcoming 9R outage.
Final scheduling for these modifications will be done in accordance with the Integrated Schedule evaluation process.
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GPU Nuclear Corporanon is a subsidiary of General Public Utikties Corporahon
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< I '* July 19,'1990 -
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- C311404085 1
The Containment High bnge Radiation Monitors and associated i
instrumentation were oridnally installed to meet NUREG-0737 requirements ~
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. as a plant restart commitment. ' These instruments were installed in accordance with NUREG-0737, Appendix B design criteria to the extent.
i practicable. Physical separttion of the power cables between the Distribution Panels and Control: Room Panel PRF was not provided because Panel PRF was non-seismic.. Technical Spedfication operability -
requirements were applied to these conitors-at that time'.
Panel PRF has
. subsequently been seismically qualifud.
- The.TMI-1 Technical Specification, Sec'; ion 3.5.5, specifies that two channels of Containment High Range. Radiation Monitors (RMG-22 and 23) shall be operable during power operation.
Fo* the interim period until physical-1 separation and isolation is provided, we consider both Containment High Range Radiation Monitors (RMG-22 and 23) to be capable of performing their design function which is to provide post-Occident radiat % monitoring inside the containment building. The Containment High Range Radiation Monitors have fully qualified and separated high voltage and signal circuits between Control Room Panel PRF and the "D" rings-inside containment where the detectors are mounted. The entire installation is seismically qualified and mounted. A recent circuit walkdown found one cable tray support brace missing which has been reinstalled. The shared section of cable tray is a'section approximately 20 feet in length in the Control-Building. The ratematers in Panel PRF are physically: separated i
with a flame barrier, and Panel PRF is now seismically qualified. Adequate electrical isolation is provided in the Distribution Panel to prevent any
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potential faults from degrading the 120 VAC vital-power sources. The. cable-routings which lack' physical separation in accordance with'SDD 772-A are not subject to high energy line breaks or any high voltage conditions.
These routings are limited to safety related, seismically designed areas of the Control Building. ' Panel PRF is located in a mild environment. As a result, no credible degradation mechanism has been identified which could
- disable both monitors in conjunction with a design basis accident for which this monitoring function is required..Since the operators can continue to rely on these instruments, we consider these monitors to be operable in accordance with Technical Specification requirements.
This issue was discussed.with NRC Region I personnel on June 1, 1990.
Sincerely, i
- Mbbb4k, hrH.D.Hukill Vice President & Director, TM1
- HDH/DJD/pp cc: J. Stolz, USNRC R. Hernan, USNRC T. Martin, USNRC, Region 1 F. Young, USNRC, TMI-1
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