ML20237F070
| ML20237F070 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/23/1987 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 5211-87-2192, NUDOCS 8712290338 | |
| Download: ML20237F070 (2) | |
Text
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0 GPU Nuclear Corporation i
Gm Nuclear
- =, ors =8o Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
December 23, 1987 5211-87-2192 U. S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, D.C.
20555 Gentlemen:
l l
Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Technical Specification Change Request No.158 -
Chlorine Detection System Response to NRC Request for Additional Information In accordance with NRC request, this letter confirms telephone discussions with NRC Region I personnel regarding:
- 1) the means for ensuring that the j
maximum size containers of chlorine on site will be within the design basis, j
and 2) justification for not incorporating additional periodic tests of the system response time.
TMI-1 FSAR Update 7 will include in FSAR Section 7.4.5 a statement that the 1
chlorine detection system is provided to protect control room operators in the event of an onsite release of chlorine gas due to a rupture of a one-ton I
cylinder of liquid chlorine at either the river water chlorinator or the Unit l
l l circulating water chlorinator.
This FSAR revision will document that the design basis for the chlorine detection system is the rupture of a one-ton cylinder.
Documentation of this basis in the FSAR provides adequate assurance that the on-site storage of chlorine will be restricted to a maximum container size of one-ton unless an appropriate safety evaluation is conducted to determine the acceptability of the consequences of the rupture of a chlorine cylinder larger than one-ton.
In addition, purchases of liquid chlorine will be restricted to single container sizes of one-ton or less and hazardous material control procedures will restrict delivery of liquid chlorine to single container sizes of one-ton or less.
Periodic tests of the chlorine detection system include a weekly channel check for the detector alarm and trip setpoints, a monthly test using a probe simulator to verify proper response of the chlorine detection system instrumentation including alarn indication and isolation of the control building ventilation system, and a calibration of the detectors on a refueling interval basis.
In addition to these surveillance, a weekly preventive maintenance procedure has been instituted which conducts a sensitivity check to verify that the detector responds to a low ppm chlorine concentration. The g
GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation hO 8712290338 871223
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5211-87-2192 chlorine detection system has a self-diagnostic feature which checks the electrolyte level in the detector.
In addition, automatic initiation of control-building isolation and recirculation dampers is demonstrated as operable in accordance with existing TMI-1 Technical Specification Section 4.12.1.3 at least once per refueling outage or once every 18 months whichever occurs first.
The analysis of chlorine release for TMI-1 assumes detectors with a 10 second response' located'at the river water chlorinator and the mouth of the air intake tunnel, and upon detection, all fans are shutdown and dampers are closed. Single failures considered included failure of the intake fan to shutdown or failure of the damper to close. The limiting single failure is the failure of the intake fan to shut down since this results in a higher air l
inleakage into the control room. The results of this analysis show that for all cases at least two minutes are available from receipt of the detector.
alarm to don emergency breathing apparatus, even considering the worst case I
single failure in the isolation system. : Therefore, as demonstrated by this analysis, the concentration of chlorine in the control room within the first two minutes following a release on site'is not sensitive to the system response time.
Both independent chlorine detection system instrumentation channels were verified to have response times less than 10 seconds as part of the startup and test program for this system. This satisfies the requirements of Regulatory Guide 1.95, Rev.1, Regulatory Position C.3.a(1).
I We feel that the proposed and existing technical specification surveillance and the startup tests described above provide adequate assurance of sufficient I
capability to promptly detect and initiate protective action in the event of l
an accidental chlorine release.
I Sincerely, P
. D.
ill Vice President and Director TMI-1 HDH/DJD:fg 5719g/1066A cc:
J. Stolz G. Edison l
W. Russell R. Conte
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