ML20247N744
| ML20247N744 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 06/02/1989 |
| From: | Parker T NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| IEB-88-008, IEB-88-8, NUDOCS 8906060014 | |
| Download: ML20247N744 (2) | |
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Y Northem States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401-1927 Telephone (612) 330-5500 June 2, 1989 NRC Bulletin No. 88-08 Director of Nuclear Reactor Regulation U S Nuclear Regulatory Commission Attn:
Document Control Desk Washington,- DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Supplemental Response to NRC Bulletin No. 88-08 Thermal Stresses in Piping Connected to Reactor Coolant Systems In accordance with the requirements specified in Reporting Requirement 2 of NRC Bulletin No. 88-08, Thermal Stresses in Piping Connected to Reactor Coolant: Systems, this letter confirms that Actions 2 and 3 of the bulletin have been completed for Prairie Island Units 1 and 2.
As reported in our September 30, 1988 response to NRC Bulletin No. 88-08, only the auxiliary pressurizer spray lines could potentially be subjected to thermal stresses of the type described in the bulletin. The weld which joins the 2" auxiliary pressurizer spray line to the tee at the 3" pressurizer spray line was judged to be the most susceptible region for such thermal stress to occur.
This area has been examined by NDE techniques on Unit 1 and Unit 2.
These examinations found no evidence of pipe cracking on either unit.
To provide continuing assurance that thermal stress induced cracks do not develop, NDE examination of the susceptible region, as described in our September 30, 1988 response, will be repeated every third refueling outage.
This inspection frequency is conservatively based on the time for a crack to initiate and then to propagate to an unacceptable size as a result of the valve leaking at what was determined to be the worst-case leak rate for inducing thermal stress.
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' Please contact us if you have any questions related to,this response.
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.s-Thomas M' Parker.
Manager Nuclear Support Services p-c:: Regional Administrator III, NRC F;
Sanior Resident Inspector, NRC
' NkR Project Manager, NRC G:Charnoff.
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