ML20070E105
| ML20070E105 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 07/08/1994 |
| From: | Hill W NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-93-003, IEB-93-3, NUDOCS 9407140086 | |
| Download: ML20070E105 (3) | |
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Northem States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401 1927 Telephone (612) 330-5500 July 8, 1994 NRC Bulletin 93-03 U S Nuclear Regulatory Commission Attn; Document Control Desk Washington, DC 20555 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Follow-Up Response to NRC Bulletin 93-03: Resolution of Issues Related to Reactor Water Level Instrumentation in BWRs This letter is being provided to satisfy the final remaining reporting requirements contained in NRC Bulletin 93-03 (" Resolution of Issues Related to Reactor Water Level Instrumentation in BWRs", dated May 28, 1993) for the Monticello Nuclear Generating Plant.
Bulletin 93-03 contained three reporting requirements:
Reporting Requirement (1) did not apply to Monticello since short term actions were taken as requested by the bulletin.
Reporting Requirement (2) specified that by July 30, 1993, all addressees submit a written report providing the description of the short term compensatory actions taken in response to the bulletin and a description of the hardware modifications to be implemented at the next cold shutdown af ter July 30, 1993. Our response to this item was submitted as required on July 30, 1993 and was subsequently modified by NSP letters to the NRC dated December 29, 1993 and March 31, 1994.
Reporting Requirement (3) of the bulletin 93-03 specified that within 30 days of completion of the requested hardware modifications, a report be submitted to the NRC confirming completion and describing the modifications implemented.
This letter is intended to satisfy the third reporting requirement.
Installation of the hardware modification at Monticello is complete and the system is in operation.
Preliminary installation work was performed during late 1993 and early 1994 and the final system tie-ins were completed during a j
short duration cold shutdown that occurred from June 5 to June 10, 1994.
The system was pre-operationally tested during the cold shutdown and, as described in our March 31, 1994 letter, was placed into partial service (one division) to allow additional on-line monitoring during start-up and full power operations.
On-line monitoring has been completed and both divisions of the new system are now in service.
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July 8, 1994 Page 2 The new system, referred to as the reference leg backfill system, is similar in design and function to the system installed at Millstone Unit 1.
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system utilizes water supplied from the Control Rod Hydraulic (CRDH) system to backfill the safeguards and fuel zone level instrument reference legs.
CRDH water is normally supplied from the Condensate & Feedwater system immediately downstream of the Condensate Demineralizers and is therefore high quality with low dissolved gas content.
Backfilling from this source prevents the build-up of non-condensible gases in the reference legs and minimizes the potential for gas bubble formation during pressure reduction transients. The system design includes flow monitoring instrumentation and manual metering valves to control the backfill flow rate and incorporates redundant safety grade check valves to provide the necessary containment isolation function. Additional details of the Monticello design were presented to the NRC staff at meetings held at NRC Headquarters on September 29, 1993 and March 22, 1994.
Both divisions of the system will normally be in service and backfilling on a continuous basis during power operation.
The new system was subjected to a series of tests during the installation and pre-operational phases to confirm, to the extent practical, that anticipated CRDH system transients would not affect the existing reactor water level instrumentation. As noted previously, additional monitoring was performed during and after start-up.
As a result of the testing and monitoring we have concluded the system is functioning as intended with no significant adverse affects and consider it to be fully operational.
We consider this letter to complete the reporting requirements of Bulletin 93-03.
This letter contains no new NRC commitments.
Please contact Terry Coss, Sr Licensing Engineer, at (612) 295-1449 if you require further information concerning this issue.
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William J Hill Plant Manager Monticello Nuclear Plant cc: Regional Administrator-III, NRC NRR Project Manager, NRC Resident Inspector, NRC State of Minnesota, Attn: Kris Sanda J Silberg
Attachment:
Affidavit to the US Nuclear Regulatory Commission-
UNITED STATES NUCLEAR REGULATORY COMMISSION NORTHERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT DOCKET NO. 50-263 Follow-Up Response to NRC Bulletin 93-03: Resolution of Issues Related to Reactor Water Level Instrumentation in BWRs Northern States Power Company, a Minnesota corporation, hereby provides the information requested by NRC Bulletin 93-03: Resolution of Issues Related to Reactor Water Level Instrumentation in BWRs.
This letter contains no restricted or other defense information.
NORTHERN STt.TES POWER COMPANY I
Dv By William-J Hill Plant Manager Monticello Nuclear Plant
/ k k Y before me a notary public in and On this ay of
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Nuclear Plant and being % ' appeared William J Hill, Plant Manager, Monticello for said County, persona first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof, and that to the best of his knowledge, information, and belief the statements made in it are true and that it is not interposed for delay.
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