ML20063C545

Provides Confirmation of Info Discussed in Earlier Telcons Re Containment Purging & Venting During Normal Operation

ML20063C545
Person / Time
Site:	Prairie Island
Issue date:	08/23/1982
From:	Musolf D NORTHERN STATES POWER CO.
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8208270294
Download: ML20063C545 (4)

Text

Nodhern States Power Company 414 Nicollet Mall Minneapons. Minnesota 55401 Telephone (612) 330 5500 August 23, 1982 Director Office of Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos 50-282 License Nos DPR-42 50-306 DPR-60 Containment Purging and Venting during Normal Operation In a letter dated April 30, 1982 we provided additional information required by the NRC Staf f and their contractors for the long-term review of the Prairie Island containment purge and vent system. We have also had followup telephone conference calls with our Project Manager in the Division of Licensing and other members of the Staff in recent weeks. During these discussions we informed the Staff of changes in the way we intend to implement modifications discussed in our April 30, 1982 letter and provided our comments related to a draft NRC Staff Safety Evaluation Report dealing with the containment purge and vent system, purge and vent isolation reset logic, and reset circuitry used in other emergency safety feature logic. The purpose of this letter is to document the information we provided earlier on an informal basis.

36-Inch Containment Purge System Modifications Following installation of the blind flanges in the Unit 2 36-inch purge system as originally planned, it was found that the inboard valve shaft seal could still provide a leakage path outside containment. To eliminate this concern, the modification to the 36-inch system will therefore also include removal of the inboard isolation valve intervals and actuator and plugging the shaft penetration with welded plugs or complete valve removal. The double gasketed seal will serve as the barrier to containment leakage inside containment. The blind flange will be removed only during cold and refueling shutdown conditions. A Type B test will be performed following replacement of the blind flange prior to going above cold shutdown.

o3 8208270294 820823 PDR ADOCK 05000282 P PDR

Director Office of NRR 8/23/82 Page 2 18-inch Containment Purge System Modifications A recent review of the 18-inch containment purge modification resulted in an alteration of our original plans. As originally designed, personnel would need to enter containment to remove the blind flanges and install the debris screen. To reduce radiation exposure and increase safety, the plan now is to install the blind flanges outside containment, in the annulus, between the two existing isolation valves.

The debris screen will be permanently installed in the containment.

Refer to the attached figure.

Administrative Controls and Annunciation of Logic Reset Reset of the containment spray and containment isolation logic are not currently annunciated in the control room. In addition, physical features are not provided to facilitate administrative controls of these reset features. During a telephone conference call on August 10, 1982 we agreed to provide annunciation of these reset conditions and provide covers for the reset push buttons. These modifications to the control room board will be designed and implemented as part of the overall control room modification resulting from the human factor studies for Prairie Island. Modifications are currently planned for implementation in 1984.

Technical Specification Changes Within 90 days of receipt of the NRC Staff's Safety Evaluation Report related to this issue we will propose Technical Specification changes in the following areas:

a. Type B tests for the blind flanges on both the 36-inch and 18-inch containment purge systems following replacement as prescribed by 10 CFR Part 50 Appendix J.

b. Type C tests for the 18-inch containment purge valves prior to use of the system when reactor is above cold shutdown.

c. The requirement to have blind flanges installed on the 36-inch purge system prior to going above cold shutdown.

Director Office of NRR 8/23/82 Page 2

d. The requirement to limit the use of the 18-inch inservice purge to "as low as reasonable achievable". When not in use, the blind flanges will be installed in the 18-inch systems.

Please contact us if you have any questions related to the information we have provided, w

David Musolf Manager of Nuclear Suppor Services DMM/SAF/js Regional Admin-III, NRC Resident Inspector, NRC G Charnoff Attachment l

Dir:ctor Office of NRR Attachm:nt

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