ML050960227

Independent Spent Fuel Storage Installation Summary of Facility Changes, Tests and Experiments

ML050960227
Person / Time
Site:	North Anna
Issue date:	03/29/2005
From:	Jennifer Davis Virginia Electric & Power Co (VEPCO)
To:	Document Control Desk, Office of Nuclear Material Safety and Safeguards
References
05-153
Download: ML050960227 (2)

Text

VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 March 29, 2005 United States Nuclear Regulatory Commission Serial No.05-153 Attention: Document Control Desk NAPS/JRP Washington, DC 20555-0001 Docket No. 72-16 License No. SNM-2507 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION INDEPENDENT SPENT FUEL STORAGE INSTALLATION (ISFSI)

SUMMARY

OF FACILITY CHANGES, TESTS AND EXPERIMENTS Pursuant to 10 CFR 72.48(d)(2), enclosed, is a summary description of the Facility changes, tests, and experiments made to the North Anna Power Station - ISFSI facility during 2004.

If you have any questions, please contact us.

Enclosure:

Attachment 1 cc: United States Nuclear Regulatory Commission Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. J. T. Reece NRC Senior Resident Inspector North Anna Power Station fj-5-50

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ATTACHMENT 1 NORTH ANNA UNITS 1 & 2 ANNUAL

SUMMARY

OF 10 CFR 72.48(d)(2). FACILITY CHANGES.

TESTS & EXPERIMENTS Regulatory Evaluation Number: 01-SE-MOD-01 Document Evaluated: DCP-01-002, TN-32 SPENT FUEL STORAGE CASK MODS.,

North Anna Units 1 & 2.

Brief

Description:

The TN-32 Cask lid seal was modified to reduce water intrusion and the overpressure system (OP) pressure-sensing instrumentation was relocated to allow easier access / support ALARA.

Reason for Change: To improve TN-32 Cask reliability and reduce personnel dose.

Summary: This evaluation involved enhancements to the TN-32 Cask lid seal.

Specifically, it: a) reduced the possibility of water intrusion which could lead to o-ring degradation and b) relocated the overpressure system (OP) pressure-sensing instrumentation from under the protective cover to an instrumentation box mounted on the side of the cask to allow easier access.

The evaluation concluded that the above-noted changes did not affect a design function, method of performing or controlling the function or an evaluation that demonstrated that the intended functions will be accomplished. Additionally, it was not determined to be a departure from a method of evaluation described in the ISFSI SAR since:

• The shielding properties of the protective cover were not changed (i.e. the access plate is made of the same material and thickness as the rest of the cover)

• The protective cover provided environmental protection and the overpressure system performs the non-safety-related function of monitoring the cask seals, therefore while the exposed tubing will be more vulnerable to damage from debris in high winds, the OP system provides no safety function, therefore its failure would not lead to an un-analyzed accident.

• The protective cover is modeled in the shielding analyses and provides no neutron shielding. Similarly, gamma shielding was determined to be negligible compared to the axial shielding of the cask.

• Safety limits and margins of safety for the TN-32 cask were not changed. The TN-32 confinement vessel continues to meet structural design requirements and will continue to perform as designed in accordance with TS requirements.

• Modifications to the protective cover did not involve a significant increase in occupational exposure. Installation of the modified protective covers onto previously loaded casks at the site will require personnel to work in a radiation area. However, the design modifications will allow personnel to access the cask pressure switches without removing the protective cover and standing at the top of the cask where the dose rate is high.