Information Notice No. 95-28: Emplacement of Support Pads for Spent Fuel Dry Storage Installations at Reactor Sites

                                 UNITED STATES
                         NUCLEAR REGULATORY COMMISSION
               OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
                          WASHINGTON, D.C. 20555-0001

                                 June 5, 1995


NRC INFORMATION NOTICE 95-28:  EMPLACEMENT OF SUPPORT PADS FOR SPENT FUEL DRY
                               STORAGE INSTALLATIONS AT REACTOR SITES


Addressees

All holders of operating licenses or construction permits for nuclear power
reactors.

Independent spent fuel storage installation designers and fabricators. 

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees to the importance of complying with all conditions
and requirements specified in Section 72.212(b) of Title 10 of the Code of
Federal Regulations (10 CFR 72.212(b)) and other applicable NRC regulations
before using certified casks under the provisions of the general license under
10 CFR Part 72 for the dry storage of spent fuel.  It is expected that the
recipients will review this information notice for applicability to their
facilities and consider actions, as appropriate.  However, suggestions
contained in this information notice are not NRC requirements; therefore, no
specific action or written response is required.

Background

The NRC reviews and approves cask designs for use in storing spent fuel under
a general license as stated in Subpart L of 10 CFR Part 72.  Approved cask
designs are listed in Subpart K of 10 CFR Part 72, (10 CFR 72.214), and a
certificate of compliance is issued to the cask designer after the rulemaking
approving the cask design is completed.  Once a cask design has been certified
and casks fabricated, casks may be used to store spent fuel at nuclear power
reactor sites in accordance with Subpart K of 10 CFR Part 72.  Such a license
is only available to utilities that hold a license to possess or operate a
power reactor under 10 CFR Part 50.  

Before storing spent fuel under the general license, reactor facility
licensees must meet the requirements stated in 10 CFR 72.212(b).  Notably,
they must--

      .   Determine and document that storage activities are in accordance
          with the provisions and conditions of the certificate of compliance
          for the cask.

      .   Ensure that reactor site parameters, including any external hazards,
          are enveloped by the design-basis values established in the cask 

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          design safety analysis report referenced in the certificate of
          compliance and the related NRC safety evaluation report.

      .   Determine whether cask use will involve a reactor facility
          unreviewed safety question or a change to the facility technical
          specifications (10 CFR 50.59).

      .   Review and modify the reactor facility quality assurance program,
          security program, emergency plan, training program, and radiation
          control program to include spent fuel storage activities as
          appropriate.

      .   Develop reactor facility written operating procedures for cask
          handling and storage operations.

This information notice discusses circumstances regarding the emplacement of
spent fuel dry storage cask pads. 

Spent fuel storage cask designs are analyzed for normal, off-normal, and
accident conditions, including tip-over and cask drop accidents.  In instances
where the pad supporting the casks, including the foundation beneath the pad,
is not relied upon to perform a safety function, it is not treated as safety
related or as important to safety.  The cask design safety analysis report
does not analyze for the effects of earthquakes, soil stability, or erosion on
the cask pad and foundation.

However, 10 CFR 72.212(b)(2) requires that the general licensee ensure that,
"cask storage pads and areas have been designed to adequately support the
stati[c] load of the stored casks."  Section 72.212(b)(3) states that the
licensee shall, "determine whether or not the reactor site parameters,
including analyses of earthquake intensity and tornado missiles, are enveloped
by the cask design bases."  The holder of a general license performs these
evaluations to ensure that the design and construction of the cask storage pad
is adequate to support the static load of the fully loaded storage casks.  In
addition, if potential conditions exist at the reactor site that could
unacceptably diminish cask safety by any credible means, then the licensee
must evaluate the potential conditions to verify that impairment of cask
safety is highly unlikely.  These evaluations are reviewed during NRC
inspections and audits of licensee operations.  

Description of Circumstances

During its initial siting analysis for dry spent fuel storage at the Palisades
facility, Consumers Power Company (the licensee) noted that the peak ground
acceleration used in the initial analysis for siting the power plant was 0.2g. 
The design-basis ground motion for the spent fuel dry storage casks is a peak
ground acceleration of 0.25g.  Therefore, the licensee determined that the
safe shutdown ground acceleration of the site was enveloped by the design
basis for the cask.  No additional analyses were performed for the siting
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Since the Palisades plant is in close proximity to Lake Michigan, questions
were raised by the NRC staff and interested members of the public regarding
the possible effects of earthquakes on soil liquefaction, wind and wave
effects on ground erosion, and the effects of these phenomena on the cask
support pad and the spent fuel storage casks.

As a result of these questions, the licensee performed a detailed analysis of
the effects of soil erosion, including the effects of high lake waves, wind,
and rain on the cask support pad.  In addition, the licensee analyzed the
effect of a safe shutdown earthquake (SSE) on soil and foundation stability,
based on both existing soil data and new data acquired from additional soil
borings taken in response to the questions regarding the stability of the pad
site.  

Other questions addressed by the review included the following:

      .   Whether there had been any changes in the general site conditions
          since the submittal of the environmental impact statement for
          licensing of the facility (e.g., stability of site topography and
          wind erosion concerns).

      .   Whether there was sufficient vertical and horizontal separation
          between Lake Michigan and the pad location to provide a conservative
          margin against wave-driven erosion.

      .   Whether the cask support pad had been analyzed for the SSE peak
          ground acceleration defined for the Palisades site.

      .   Whether the geologic and seismological analyses had been properly
          performed.

The results of the licensee analysis showed that the pad could support the
casks safely.  These results are documented in a letter to the NRC dated July
27, 1994.

NRC independently reviewed the licensee analyses of the soil liquefaction
effects on pad integrity, the pad design and construction, and the stability
of slopes surrounding the pad to determine both the long-term effects of
erosion under normal conditions and the effects of a postulated earthquake. 
This independent analysis also concluded that the cask pad would adequately
support the cask as required by 10 CFR 72.212.  The NRC independent assessment
of the licensee analysis is documented in the "Independent NRC Staff Final
Safety Assessment of the Dry Spent Fuel Cask Storage Facility at Palisades
Nuclear Power Plant Site," dated September 20, 1994.

Discussion

Potential dry cask storage users are required by 10 CFR 72.212 to perform
written evaluations, before use, that establish that the conditions for using
NRC-approved spent fuel storage casks set forth in the certificate of
compliance have been met.  These evaluations include review of the cask design

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safety analysis report and the related NRC safety evaluation report to ensure
that the reactor site parameters are enveloped by the cask design bases.  The
licensee is also required to perform a written evaluation that ensures that
the cask storage pad and areas are designed to support the static load of the
stored cask.  The effects of a postulated earthquake based on the earthquake
ground motion used for the plant design-basis SSE is valid for the storage 
casks without further analysis only if the foundation geology for the cask pad
is the same as that for the plant.  A different soil amplification resulting
from SSE ground motion at the pad site could result in exceeding the cask
design basis.

This information notice requires no specific action or written response.  If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below.  


/s/'d by BKGrimes                         /s/'d by WDTravers

Brian K. Grimes, Director                 William D. Travers, Director
Division of Project Support               Spent Fuel Program Office 
Office of Nuclear Reactor                 Office of Nuclear Material
  Regulation                                Safety and Safeguards 

Technical contacts:  F. Sturz, NMSS
                     (301) 415-7278

                     M. Gamberoni, NRR
                     (301) 415-3024