ML20214F855
| ML20214F855 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/15/1987 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 5211-87-2100, NUDOCS 8705260320 | |
| Download: ML20214F855 (2) | |
Text
o GPU Nuclear Corporation Ng gf Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
May 15, 1987 5211-87-2100 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C.
20555 Gentlemen:
Three Mile Island Nuclear Station Unit 1 (THI-1)
Operating License No. DPR-50 Docket No. 50-289 Reactor Coolant Inventory Trending System -
Water Level Indication The TMI-1 Reactor Coolant Inventory Trending System (RCITS) is comprised of two subsystems, the water level trending subsystem and the void fraction trending subsystem. The void fraction is automatically trended when at least one of the reactor coolant pumps is operating, and the water level is automatically trended when the RCP's are off.
Automatic water level trending does not commence until such time as all four reactor coolant pumps are tripped.
Similarly, automatic void fraction trending stops on a signal that all pumps are off.
RC pump status (pump running index) is calculated using RCP motor breaker status contacts. A faulty input signal from one contact could preclude automatic trending by either the void fraction or water level subsystem during its intended operating mode. The water level trending subsystem is intended to be single failure tolerant.
Although a single failure can prevent the pre-programmed automatic trending of water level, it would not prevent the operator from calling up a trending display of the water level data. However, the limitation of this type of display is that it cannot access historical data and thus would provide data trending commencing at the time it is initiated by the operator.
(
I Q
GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
.o.i,
5211-87-2100 May 15,19L'7
~ To alleviate this ' condition, GPUN intends to disconnect the pump running index as an inhibit to trend water level, and to provide a message statement that water level data is invalid if the pumps are running. This software modification will be completed by June 30, 1987.
This letter is provided for f nformation. No NRC response is anticipated.
Sincerely, cill Vice President & Director, TMI-1 HDH/SK/pa(4684g) cc:
G. Edison, USHRC 1
l f
-.., ~,
.