RA-05-0093, Independent Spent Fuel Storage Installation, Nuhoms - 24PTH System - Thermal Performance Measurements

Independent Spent Fuel Storage Installation, Nuhoms - 24PTH System - Thermal Performance Measurements

ML052560117
Person / Time
Site:	Robinson, 07200060
Issue date:	09/09/2005
From:	Baucom C Progress Energy Carolinas
To:	Document Control Desk, Office of Nuclear Material Safety and Safeguards
References
RNP-RA-05-0093
Download: ML052560117 (3)

Text

Progress Energy Serial: RNP-RA/05-0093 SEP 0 9 2005 Document Control Desk Director, Spent Fuel Project Office Office of Nuclear Material Safety and Safeguards United States Nuclear Regulatory Commission Washington, DC 20555-0001 H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261/LICENSE NO. DPR-23 INDEPENDENT SPENT FUEL STORAGE INSTALLATION DOCKET NO. 72-60 NUHOMSO- 24PTH SYSTEM - THERMAL PERFORMANCE MEASUREMENTS Ladies and Gentlemen:

Carolina Power and Light Company, also known as Progress Energy Carolinas (PEC), Inc., is the first user of the NUHOMS- 24PTH dry fuel storage system. Four Dry Shielded Canisters (DSCs), each containing 24 spent fuel assemblies, were loaded into four Horizontal Storage Modules (HSMs) between August 11, 2005, and September 1, 2005, at H. B. Robinson Steam Electric Plant (HBRSEP), Unit No. 2.

Dry Fuel Storage Cask Certificate of Compliance (CoC) No. 1004, Amendment No. 8, Technical Specification 1.1.7, "Special Requirements for First System in Place," requires that the first user of a system take special temperature measurements and provide the results of those measurements to the NRC. This letter fulfills that Technical Specification requirement. (Note -

PEC loaded the DSCs/HSMs under an exemption issued August 4, 2005, since Amendment No. 8 to CoC No. 1004 has not yet been incorporated into 10 CFR 72. As required by the exemption, PEC is complying with the requirements of Technical Specification 1.1.7 as written in the proposed Amendment No. 8 to CoC No. 1004.)

The NUHOMS- 24PTH system is designed to store fuel with a heat load of up to 40.8 kW per DSC. PEC could not load a DSC with a 40.8 kW heat load due to restrictions placed on the heat load of individual assemblies as described in the NRC letter dated August 4, 2005. The heat loads of the four DSCs loaded are as follows:

Progress Energy Carolinas. Inc.

Robinson Nuclear Plant 35B1 West Entrance Road Hartsville, SC 29550 D I

United States Nuclear Regulatory Commission Serial: RNP-RA/05-0093 Page 2 of 3 DSC Number Date HSM Loaded Heat Load (kW)

RNP24PTH-L-2B-HZO1 August 11, 2005 25.02 RNP24PTH-L-2B-HZ02 August 19, 2005 24.71 RNP24PTH-L-2B-HZ03 August 25, 2005 23.89 RNP24PTH-L-2C-HZ04 September 1, 2005 29.35 Based on the requirements of Technical Specification 1.1.7 and the above loading history, special temperature measurements were required for the first DSC loaded and the fourth DSC loaded, since the fourth DSC exceeded the heat load of the first DSC.

The attachment provides the calculation that was used to determine the limiting temperature differential between the HSM air inlet and air outlet for the four heat loads specified above. As noted in the attachment, the methodology is the same as a previously completed calculation, which is the methodology as documented in the Final Safety Analysis Report (FSAR) for the proposed Amendment No. 8 to CoC No. 1004 for the NUHOMS- 24PTH system.

The calculated temperature differential limit is a function of both the DSC heat load and the ambient temperature. For the first DSC loaded, the heat load was 25.02 kW and the ambient temperature each day, at the time of the temperature measurements, was between 80'F and 86TF.

Based on these conditions and using Table 7-1 in the attachment, the maximum allowable temperature rise is approximately 620 F. The HSM for the first DSC was closed on August 11, 2005, and the temperature rise reached equilibrium by August 14, 2005. On August 14, 2005, the air inlet temperature was 82.7 0 F (based on an average of two measurements) and the air outlet temperature was 113.20 F (based on an average of six measurements). This gives an actual temperature rise of 30.5TF, which is significantly less than the allowable limit of 620 F.

For the fourth DSC loaded, the heat load was 29.35 kW and the ambient temperature at the time of measurement after equilibrium was reached was approximately 750 F. Based on these conditions and using Table 7-1 in the attachment, the maximum allowable temperature rise is approximately 67'F. The HSM for the fourth DSC was closed on September 1, 2005, and the temperature rise reached equilibrium by September 5, 2005. On September 5, 2005, the air inlet temperature was 74.80 F (based on an average of two measurements) and the air outlet temperature was 115.80 F (based on an average of six measurements). This gives an actual temperature rise of 41'F, which is significantly less than the allowable limit of 670F.

Based on these measurements, it can be concluded that the thermal analyses, as described in the proposed Amendment No. 8 NUHOMS- 24PTH FSAR, are conservative.

United States Nuclear Regulatory Commission Serial: RNP-RA/05-0093 Page 3 of 3 If you have any questions concerning this matter, please contact me at 843-857-1253.

Sincerely, C. T. Baucom Supervisor - Licensing/Regulatory Programs RAC/rac Attachment c: Dr. W. D. Travers, NRC, Region II Mr. C. P. Patel, NRC, NRR NRC Resident Inspectors, HBRSEP Mr. L. R. Wharton, NRC, NMSS