ML20058M222
| ML20058M222 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 09/27/1993 |
| From: | Richard Anderson NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-88-14, TAC-M71684, NUDOCS 9310040293 | |
| Download: ML20058M222 (2) | |
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6-A I1 Northem States Power Company 414 Nicollet Mall Minneapohs, Minnesota 55401-1927 T6:ephone (612) 330-5500 September 27, 1993 US Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C.
20555 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Revised Information Concerning the Monticello Response to Generic Letter 88-14, " Instrument Air System Problems Affecting Safety-Related Eauipment" (TAC No. 71684)
The purpose of this letter is to bring to your attention revised information concerning a submittal we provided on February 17, 1989 in response to NRC Generic Letter 88-14 " Instrument Air System Problems Affecting Safety-Related Equipment" dated August 8, 1988.
Generic Letter 88-14 requested, in part, that each licensee / applicant provide a discussion of the program for maintaining proper instrument air quality.
In response to that specific question, our February 17, 1989 letter stated (in part) that:
" Instrument air humidity is continuously monitored at the outlet of the after filters. A high humidity condition is alarmed in the control room."
Recently, while reviewing NRC commitments associated with the instrument air system, the cognizant System Engineer identified that the above description r
was incorrect both now and at the time of our February 17, 1989 submittal due to a system modification that had been completed in December of 1987.
The-modification, which installed the first heaterless air dryer in the instrument air system, removed the humidistat that had previously been installed at the outlet of the instrument air dryer. This humidistat was the device that had been providing a local (not control room) alarm in the event of high humidity in the instrument air system.
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Upon reassessment of this issue, a more appropriate response to Generic Letter 88-14 concerning on-line monitoring an? alarm features of the instrument air system is as follows-1
" Instrument air dryer performance and instrument air dryer pressure drop are monitored during each shif t by operations personnel.
Degraded dryer performance such as excessive moisture loading of the desiccant beds or dryer valve malfunctions are sensed in the dryer and will alarm locally and in the control room."
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i USNRC NORTHERN STATES POWER COMPANY September 27, 1993 I
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l We regret the error in our February 17, 1989 submittal, but believe that the on-line monitoring and alarm features of the instrument air system (described above) that existed at the time and that remain in place today are superior to those identified in our earlier letter, which inadvertently described the system as it existed prior to the 1987 modification.
These features, as well as the new heaterless air dryers (two of which are now installed) serve to enhance system performance and further ensure a reliable source of high i
quality instrument air to safety related and balance of plant equipment.
This letter is provided for your information only and no specific action or response is required.
This letter contains no new NRC commitments, nor does it modify any prior commitments.
Please contact Terry Coss, Sr Licensing Engineer, at (612) 295-1449 if you require additional information.
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Roger a Anderson Director i
Licensing and Management Issues cc: Regional Administrator-III, NRC NRR Proj ect Manager, NRC Resident Inspector, NRC State of Minnesota, Attn: Kris Sanda l
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