ML070720768
| ML070720768 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 03/20/2007 |
| From: | Strosnider J Office of Nuclear Material Safety and Safeguards |
| To: | Lodge T - No Known Affiliation |
| Hall J, NMSS/SFPO (301) 415-1336 | |
| Shared Package | |
| ML070720752 | List: |
| References | |
| 50-255, 72-7 (2.206), DD-07-02, G20060369, RAS 13887 | |
| Download: ML070720768 (6) | |
Text
DD-07-02 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS Jack R. Strosnider, Director In the Matter of ) Docket Nos. 50-255, 72-7
)
NUCLEAR MANAGEMENT COMPANY, LLC ) License No. DPR-20
)
Palisades Nuclear Plant )
DIRECTORS DECISION UNDER 10 CFR 2.206 I. Introduction By letter dated April 4, 2006, Mr. Terry J. Lodge, on behalf of five organizations and 30 individuals (the Petitioners), filed a petition pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Section 2.206, with the U.S. Nuclear Regulatory Commission (NRC or the Commission). The Petitioners requested that NRC take enforcement action against the licensee for the Palisades Nuclear Plant, Nuclear Management Company, LLC (NMC), by condemning and stopping the use of the two independent spent fuel storage installation (ISFSI) concrete pads holding dry spent fuel storage casks on the plant site. As the basis for the request, the Petitioners stated that the concrete cask storage pads do not conform with NRC regulations for earthquake stability, specifically 10 CFR 72.212(b)(2)(i)(B) and 72.212(b)(3),
and, therefore, pose a hazard in case of an earthquake.
Representatives for the Petitioners participated in a telephone conference call with NRCs Petition Review Board (PRB), on April 26, 2006, to discuss the petition. The teleconference was transcribed and the transcription was treated as a supplement to the petition. In the conference call, the Petitioners requested additional time to provide supplemental information. The PRB agreed and asked the Petitioners to submit any such
information within one week of receiving a transcript of the conference call. A written transcript of the call was sent to the Petitioners on May 3, 2006. The Petitioners did not submit any supplemental information subsequent to the receipt of the transcript.
In a letter dated June 27, 2006, NRC accepted the petition, in part, for review under 10 CFR 2.206, specifically with respect to the slope stability analysis of the concrete pad constructed in 2003. That issue was already under NRC review at the time the Petition was submitted, since NRC had identified it as an unresolved item in NRC Inspection Report 07200007/2004-002, dated September 3, 2004, concerning a dry-cask storage inspection at the Palisades site conducted in August 2004. The other issues the Petitioners raised, concerning the stability of the older concrete pad constructed in 1992, and the potential for amplification of earthquakes on the newer pad, were not accepted for review under 10 CFR 2.206, because the NRC staff had already evaluated and resolved those issues. The staffs review of the older pad is documented in the Palisades Plant - NRC Final Safety Assessment of ISFSI Support Pad, dated September 20, 1994. In that assessment, the staff had concluded that the location of the storage pad at the Palisades site was acceptable to support the concrete storage casks against all effects of the design basis earthquake for the site. The staff resolution of potential amplification effects from seismic events on the newer pad was documented in NRC Inspection Report 05000255/2006002, dated May 11, 2006. In that inspection report, the staff concluded that the potential soil-structure interaction and soil liquefaction due to earthquakes were correctly factored into the licensees seismic analysis of the newer pad, and that the licensees results met the design limits for the storage cask system.
In its June 27, 2006, letter, NRC also informed the Petitioners that their request for immediate action to condemn and stop the use of the two ISFSI concrete pads at the Palisades site was denied because continued storage of spent fuel in dry casks on the existing concrete pads, while the issues raised by the petition were evaluated, would not pose an undue risk to
public health and safety.
Copies of the petition, transcript, and acknowledgment letter are available for inspection at the Commissions Public Document Room (PDR) at One White Flint North, Public File Area O-1F21, 11555 Rockville Pike (first floor), Rockville, Maryland, and from NRCs Agencywide Documents Access and Management System (ADAMS) Public Electronic Reading Room on the NRC Web site at http://www.nrc.gov/reading-rm/adams.html, under ADAMS Accession Nos. ML060960061, ML061230089, and ML061790450, respectively. The NRC safety assessment, dated September 20, 1994, and the May 2006 NRC Inspection Report can be found at ADAMS Accession Nos. ML060480227 and ML061350371, respectively. Persons who do not have access to ADAMS or who have problems in accessing the documents in ADAMS should contact the NRC PDR reference staff, by telephone, at 1-800-397-4209, or 301-415-4737, or by e-mail, to pdr@nrc.gov.
II. Discussion Regarding the issue the staff accepted for review under 10 CFR 2.206, the Petitioners have asserted that the newer (2003) ISFSI concrete pad at the Palisades site does not comply with the requirements of 10 CFR 72.212(b)(2)(i)(B) and 72.212(b)(3). These regulations require that a general licensee wishing to use an NRC-approved dry-cask storage system at its site must perform written evaluations before such use, establishing that cask storage pads and areas have been designed to adequately support the static and dynamic loads of the stored casks, considering both potential amplification of earthquakes through soil-structure interaction, and soil liquefaction potential or other soil instability from vibratory ground motion. In addition, the general licensee must review the Safety Analysis Report referenced in the Certificate of Compliance and the related NRC Safety Evaluation Report before use, to determine whether the reactor site parameters, including analyses of earthquake intensity and tornado missiles, are enveloped by the cask design bases considered in these reports. In 2004, NRC conducted
an inspection of spent fuel storage activities at Palisades and reviewed the licensees written evaluations, as documented in NRC Inspection Report 07200007/2004-002, dated September 3, 2004 (ADAMS Accession No. ML042510075). In that inspection report, NRC concluded that, in general, the licensees written evaluations of the cask system were adequate to demonstrate compliance with the requirements of 10 CFR 72.212(b). However, two unresolved items requiring further NRC evaluation were identified: (1) the potential amplification effects of seismic events on the new ISFSI pad; and (2) the slope/subsurface stability analysis. The potential amplification effects of seismic events on the newer pad have since been reviewed and resolved, as documented in NRC Inspection Report 05000255/2006002. The NRC staff has recently completed its review of the licensees revised slope stability analysis for the newer pad and resolved the issue, as discussed below.
On October 19, 2006, NMC completed a revised slope stability analysis for the newer ISFSI pad [NMC Calculation (Doc) No: EA-EC7408-02, Revision 0, Re-evaluation of Slope Stability under ISFSI Pad for Revised Load Due to 24PTH System, ADAMS Accession No. ML063260200]. NMC performed the reevaluation to address NRC questions associated with the unresolved inspection item, and to confirm the stability of the newer pad for the possible use of a cask design heavier than that currently in service. The NRC staff has reviewed the licensees new evaluation, and concludes the following:
- 1. The soil properties the licensee determined from three samples taken in the vicinity of the newer ISFSI storage pad were adequate for use in the design of the pad. The short-term effects of rain and snowfall on the critical soil parameters would be insignificant, because a small change in moisture content would result in only a small change in total density, which would not affect the overall stability of the ISFSI pad.
- 2. The licensees revised evaluation appropriately considered the weight of the as-
built pad, the weight of the heavier cask system, and the in-situ soil properties, in response to an earthquake. NRC guidance, and government and commercial standards for the design of foundations of similar structures indicate that a minimum acceptable factor of safety of 1.15 is appropriate when considering transient loadings such as a design basis seismic event. NMCs revised evaluation concluded that this design criterion is met for all areas and soils beneath and immediately around the pad. The NRC staff has reviewed this analysis and concludes that NMC has satisfactorily demonstrated that the as-built pad has an adequate factor of safety of a minimum of 1.15 against the postulated sliding soil-mass loads resulting from an earthquake.
- 3. The NRC staff has determined that the analysis, results, and conclusions presented in the new NMC evaluation satisfy the design requirements for the newer pad and confirm that a factor of safety of 1.15 will exist to provide adequate margin against the effects of sliding soil slopes. The staff concludes that the slope stability analysis for the newer ISFSI pad is adequate to support the placement of existing casks and additional casks of heavier design, as analyzed by NMC in the referenced evaluation.
Based on this review, the NRC staff has closed the last unresolved item from the August 2004 NRC dry-cask storage inspection at Palisades, as documented in NRC Inspection Report 05000255/2006013, dated January 24, 2007 (ADAMS Accession No. ML070240635).
III. Conclusion The NRC staff has reviewed the basis for the Petitioners requested actions. Based on the foregoing discussion, the staff concludes that the Petitioners concerns about the stability of the newer ISFSI pad during an earthquake have been adequately resolved such that no further
licensee action is needed. NMC has performed written evaluations that establish that the newer cask storage pad at the Palisades ISFSI has been designed to adequately support the static and dynamic loads of the stored casks, considering potential effects of earthquakes, in compliance with 10 CFR 72.212(b)(2)(i)(B) and 72.212(b)(3). The staff further concludes that the Petitioners concerns have been adequately addressed by the licensees revised slope stability evaluation. Therefore, the requested action, to condemn and stop the use of the two ISFSI concrete pads holding dry spent fuel storage casks at the Palisades site, is denied.
As provided in 10 CFR 2.206(c), a copy of this Directors Decision will be filed with the Secretary of the Commission, for the Commission to review. As provided for by this regulation, this decision will constitute the final action of the Commission 25 days after the date of the decision, unless the Commission, on its own motion, institutes a review of this decision within that time.
Dated at Rockville, Maryland, this 20th day of March, 2007.
FOR THE NUCLEAR REGULATORY COMMISSION
/RA/
Jack R. Strosnider, Director Office of Nuclear Material Safety and Safeguards