ML20058G243
| ML20058G243 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 12/02/1993 |
| From: | Stetz J CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9312090145 | |
| Download: ML20058G243 (2) | |
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[CO N N E CTIC U T YA N K EE ATOMIC POWER COMPANY I
I HADDAM NECK PLANT 362 INJUN HOLLOW ROAD e EAST HAMPTON. CT 06424-3099 December 2,1993 Re: Technical Specification 6.9.2 Docket 50-213 U. S. Nuclear Regulatory Commission Document Control Desk Washington DC 20555 Ikar Sir:
Attached is a Special Report, submitted in accordance with the Haddam Neck Plant Technical Specification 3.3.3.5, Action 37 and Specification 6.9.2.
On November 16,1993, routine Surveillance testing of the Wide Range Noble Gas Stack Monitor ( RMS-14B) was completed. On the 26th of November investigations were in progress to determine why the Low Range Channel of RMS-14B was experiencing an increasing countrate. Results of the investigation revealed that the calibration source for the Low Range Channel had tape covering a damaged portion of the source. This tape essentially shielded the Beta component of the source, thus bringing into question the recent calibration of the Low Range detector. Since the source was partially shielded, the detector High Voltage and discriminator settings were set for other than the calculated source decay activity. Due to this miscalibration, the operability of the Low Range Channel of RMS-14B could not be demonstrated prior to the end of the seven day period following the Surveillance testing.
Pursuant to Technical Specifications 3.3.3.5 and 6.9.2, this report is required to be filed within ten days of the end of the seven day action statement.
Very truly yours, h
/'
John P. Stetz Vice President Haddam Neck Plant i
l ec:
Mr. Thomas T. Martin Regional Administrator, Region 1 D. Allendale Road King of Prussia, PA 19406 Mr. William J. Raymond Sr. Resident inspector lladdam Neck i
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t Special Report i
Main Stack Wide Range Noble Gas Monitor 1noperable j
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1 Introduction
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The Wide Range Noble Gas Monitor, RMS-14B is a TMI backfit that is intended to be used during accident releases. It is designed to measure radioactive gas concentrations in the range of 1.0E-07 t
to 1.0E+05 microcuries/cc of Xenon-133. This range is significantly larger than the capabilities of j
the original stack monitor, RMS-14A.
1 RMS-14B is calibrated and functionally checked on a quarterly basis using Station Procedure SUR 5.2-69, Calibration and Functional Check cf the Stack Wide Range Noble Gas Monitor (RMS-14B).
i Discussion l
On November 26,1993 at 0230, with the plant in Mode 1, investigations were under way to determine the cause for an increased countrate on RMS-14B. A damaged calibration source was determined as the root cause of the problem in that the method used to repair the source (tape)
J cffectively shielded the Beta component of the source, invalidating the last Low Range detector calibration in which the damaged source was used. This condition did not become apparent until j
after the seven day period in which to demonstrate operability as outlined in Technical Specification 3.3.3.5.
A new calibration source is being procured and the Low Range channel detector will be recalibrated to the new source.
1 During the time that the Wide Range Noble Gas Stack Monitor is out of service, routine gaseous j
effluents are adequately monitored with the back-up stack monitor, RMS-14A. Should an event j
have occurred that resulted in the radioactive effluent release rate increasing beyond the range of l
the back-up stack monitor, back-up procedures (Emergency Plan Implementation Procedures) are in place for radiation dose assessment, including the use of radiological field teams. These procedures provide adequate means to determine effluent release rates based upon calculations using field data.
On the basis that adequate alternate capabilities using the back-up stack monitor and Emergency Plan procedmes that am in place, the inoperability of RMS-14B imposed a low safety significance on our ability to assess the dose consequence of a major gaseous release.
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