ML20116N719
| ML20116N719 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 04/26/1985 |
| From: | Musolf D NORTHERN STATES POWER CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| TAC-55445, TAC-55446, NUDOCS 8505070323 | |
| Download: ML20116N719 (1) | |
Text
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Northern States Power Company
- bliet Malt Minneapohs. Minnesota 55401 Telephone (612) 330-5500 April 26,1985 Director Office 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 Supplemental Information Concerning License Amendment Amendment Request dated July 11, 1984 Item No. 4 of the July 11, 1984 License Amendment Request, concerned the replacement of the 2000 ppm Boron concentration limit with a 10% deltaK/K limit. This letter responds to an NRC Staff request for additional information concerning the' suggested 10% deltaK/K limit.
Prior to each refueling, our Nuclear Analysis Department prepares a Startup and Operations Report. Contained in this report is the boron concentration required to maintain the reactor shutdown by 10% deltaK/K with the "new" core loaded with all rods in, pressure O psig and the most limiting temper-ature between 68 and 140 degrees F.
The boron concentration is calculated by our nodal code DP5, described in NADNSP 8101P Revision 1 (submitted to the NRC on 12/13/82). A bias, determined from hot zero power benchmarks, and a bounding reliability factor are added to the baron concentration calcul-ated by DP5. The bounding reliability factor is 100 ppm (approximately 1%
deltaK/K). The standard deviation for best estimate hot zero power calcul-ations is 27 ppm, suggesting that the 100 ppm is conservative. The last three boron concentrationn Nuclear Analysis Department reported to the plant are: 2154 ppm (Unit 1 Cycle 10), 2090 ppm (Unit 2 Cycle 9) and 2150 ppm (Unit 1 Cycle 9). The plant nuclear engineer places this boron concen-tration into plant procedures to ensure that this limit is met.
Please call if you have further questions.
OO Mm David Musolf Manager - Nuclear Supp rt Services DMM/TMP/tp f of c: Regional Administrator-III, NRC O
NRR Project Manager, NRC
PDR 4