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MONTHYEARML20058A1371978-10-25025 October 1978
Submits Evaluation of Asymmetric LOCA Loads.Util Has Decided to Discontinue Participation in Util Task Group. Task Group Plan Inpractical Because of Recent Design of RCS Piping
Project stage: Other
ML19211A6581979-12-17017 December 1979
Notifies NRC That Util Cannot Meet 781025 Schedule for Resolving Issue of Asymmetric LOCA Loads,Due to Delays in Matl Procurement.Pipe Restraints Will Be Installed During Refueling Outage
Project stage: Other
ML1116511951980-04-11011 April 1980
Forwards Proprietary & Nonproprietary Versions of Structural Analysis of RCS for Postulated LOCA, Preliminary Issue.Applications for Withholding Encl. Proprietary Version Withheld (Ref 10CFR2.790)
Project stage: Other
ML19345H5081981-05-14014 May 1981
Submits Info Re Status of Mods & Analyses to Resolve Issue of Asymmetric Blowdown Loads on Primary Sys,Per 781025 & s.Vessel Nozzle Insp Port Sand Plugs Will Be Replaced W/Redesigned Low Mass Plugs
Project stage: Other
ML18092A2051984-05-21021 May 1984
Forwards Request for Addl Info Re Asymmetric LOCA Loads. Addl Info Needed in Order to Complete Safety Evaluation of plant-specific LOCA Analysis.Response Requested by 840731
Project stage: Approval
ML20092L1161984-06-15015 June 1984
Submits Plans for Resolution of Asymmetric LOCA Loads Issue, Per Generic Ltr 84-04.Westinghouse Mechanistic Fracture Evaluation & Exemption Request from GDC 4 Requirements Will Be Submitted by 840915
Project stage: Other
ML20106J5101984-10-24024 October 1984
Forwards Nonproprietary WCAP-10640 & Proprietary WCAP-10639, Technical Bases for Eliminating Large Primary Loop Pipe Rupture as Structural Design Basis for Prairie Island Unit 1. Proprietary Rept Withheld (Ref 10CFR2.790)
Project stage: Other
ML20116N6911985-04-29029 April 1985
Provides Updated Info to 841024 Submittal Re Plans for Resolving Generic Issue A-2 on Asymmetric Blowdown Loads. Westinghouse Authorized to Identify & Qualify Applicable Unit 2 Pipe Sections by 850701
Project stage: Other
ML20199D9091986-03-18018 March 1986
Notification of 860410 Meeting W/Util in Bethesda,Md to Discuss Util Progress W/Whipjet Program for Use of leak-before-break Assumption for balance-of-plant Piping. List of Attendees Provided
Project stage: Meeting
ML20214P7801986-09-10010 September 1986
Forwards Update to 851105 Submittal Re Elimination of Large Primary Loop Pipe Rupture,Including Nonproprietary Rev 1 to WCAP 10928 & WCAP 10930 & Proprietary Rev 1 to WCAP 10929 & WCAP 10931.Proprietary Repts Withheld (Ref 10CFR2.790)
Project stage: Request
ML20212F1091986-12-22022 December 1986
Safety Evaluation Supporting Elimination of Protective Devices from Design Basis for Dynamic Effects of Postulated Pipe Ruptures in Primary Coolant Loop Piping
Project stage: Approval
1984-05-21
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NSP N O R T et E R N STATES POWER COMPANY M I N N E A P80 LI S. M I N N E S OTA 55401 December 17, 1979 Director of Nuclear Reactor regulation U S Nuclear Regulatory Commission Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Installation of Pipe Restraints in Unit No. 2 Reactor Shield Wall Our letter dated October 25, 1978 outlined to the Commission our planned actions and schedule for resolving the issue of asymmetric loss of coolant accident loads. At that time our schedule called for installing pipe restraints in the Unit No. 2 reactor shield wall in the autumn of 1979 to limit the area of a break in the reactor annulus area to less than one square foot.
We will be unable to meet this schedule.
Due to delays in material procurement, the restraints will not be completed in time for installation during the next Unit No. 2 refueling outage (now scheduled for January,1980).
It appears, however, that the installation can be completed as planned during the next refueling of Unit No. 1 (now scheduled for July, 1980).
The installation of pipe restraints in Unit No. 2 will be deferred to the 1981 refueling outage.
We also tentatively plan to replace the reactor vessel nozzle inspection port sand plugs with redesigned low-mass plugs during the 1981 refueling outages. The redesigned plugs will assist in relieving pressure in the reactor annulus area due to the postulated break.
Please contact us if you have any questions related to this change in schedule.
bb L 0 Mayer, PE Manager of Nuclear Support Services LOM/DMM/ak cc: J G Keppler G Charnoff 7 912200 35'S
