[Federal Register Volume 81, Number 196 (Tuesday, October 11, 2016)]
[Rules and Regulations]
[Pages 70004-70011]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-24466]
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NUCLEAR REGULATORY COMMISSION
10 CFR Part 72
[NRC-2015-0270]
RIN 3150-AJ71
List of Approved Spent Fuel Storage Casks: Holtec International
HI-STORM 100 Cask System; Certificate of Compliance No. 1014, Amendment
No. 10
AGENCY: Nuclear Regulatory Commission.
ACTION: Direct final rule; comment responses.
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SUMMARY: On May 31, 2016, the U.S. Nuclear Regulatory Commission (NRC)
confirmed the effective date of May 31, 2016, for the direct final rule
that was published in the Federal Register on March 14, 2016. The
direct final rule amended the NRC's spent fuel storage regulations by
revising the Holtec International (Holtec) HI-STORM 100 Cask System
listing within the ``List of approved spent fuel storage casks'' to
include Amendment No. 10 to Certificate of Compliance (CoC) No. 1014.
The NRC confirmed the effective date because it determined that none of
the comments submitted on the direct final rule met any of the criteria
for a significant adverse comment. The purpose of this document is to
provide responses to the comments received on the direct final rule.
DATES: The comment responses are available on October 11, 2016.
ADDRESSES: Please refer to Docket ID NRC-2015-0270 when contacting the
NRC about the availability of information for this action. You may
obtain publicly-available information related to this action by any of
the following methods:
Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2015-0270. Address
questions about NRC dockets to Carol Gallagher; telephone: 301-415-
3463; email: [email protected]. For technical questions, contact
the individual listed in the FOR FURTHER INFORMATION CONTACT section of
this document.
NRC's Agencywide Documents Access and Management System
(ADAMS): You may obtain publicly-available documents online in the
ADAMS Public Documents collection at http://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``ADAMS Public Documents'' and
then select ``Begin Web-based ADAMS Search.'' For problems with ADAMS,
please contact the NRC's Public Document Room (PDR) reference staff at
1-800-397-4209, 301-415-4737, or by email to [email protected].
NRC's PDR: You may examine and purchase copies of public
documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555
Rockville Pike, Rockville, Maryland 20852.
FOR FURTHER INFORMATION CONTACT: Robert MacDougall, Office of Nuclear
Material Safety and Safeguards, U.S. Nuclear Regulatory Commission,
Washington, DC 20555-0001; telephone: 301-415-5175; email:
[email protected].
SUPPLEMENTARY INFORMATION:
I. Background
On March 14, 2016 (81 FR 13265), the NRC published a direct final
rule amending its regulations in Sec. 72.214 of title 10 of the Code
of Federal Regulations (10 CFR) by revising the Holtec HI-STORM 100
Cask System listing within the ``List of approved spent fuel storage
casks'' to include Amendment No. 10 to CoC No. 1014. Amendment No. 10
adds new fuel classes to the contents approved for the loading of 16 x
16 class fuel assemblies into a HI-STORM 100 Cask System; allows a
minor increase in manganese in an alloy material for the system's
overpack and transfer cask; clarifies the minimum water displacement
required of a dummy fuel rod (i.e., a rod not filled with uranium
pellets); and clarifies the design pressures needed for normal
operation of forced helium drying systems. Additionally, Amendment No.
10 revises Condition No. 9 of CoC No. 1014 to provide clearer direction
on the measurement of air velocity and modeling of heat distribution
through the storage system.
The NRC received four comment submissions with 22 individual
comments on the companion proposed rule (81 FR 13295; March 14, 2016).
Electronic copies of these comments can be obtained from the Federal
Rulemaking Web site, http://www.regulations.gov, by searching for
Docket ID NRC-2015-0270. The comments are also available in ADAMS under
Accession Nos. ML16105A426, ML16105A425, ML16105A424, and ML16105A423.
As explained in the March 14, 2016, direct final rule, the
[[Page 70005]]
NRC would withdraw the direct final rule only if it received a
``significant adverse comment.'' This is a comment where the commenter
explains why the rule would be inappropriate, including challenges to
the rule's underlying premise or approach, or would be ineffective or
unacceptable without a change. A comment is adverse and significant if:
(1) The comment opposes the rule and provides a reason sufficient
to require a substantive response in a notice-and-comment process. For
example, a substantive response is required when:
(a) The comment causes the NRC staff to reevaluate (or reconsider)
its position or conduct additional analysis;
(b) The comment raises an issue serious enough to warrant a
substantive response to clarify or complete the record; or
(c) The comment raises a relevant issue that was not previously
addressed or considered by the NRC staff.
(2) The comment proposes a change or an addition to the rule, and
it is apparent that the rule would be ineffective or unacceptable
without incorporation of the change or addition.
(3) The comment causes the NRC staff to make a change (other than
editorial) to the rule, CoC, or Technical Specifications (TSs).
The NRC determined that none of the comments submitted on the
direct final rule met any of these criteria and confirmed the effective
date of May 31, 2016, for the direct final rule on May 31, 2016 (81 FR
34241). The comments either were already addressed by the NRC staff's
preliminary safety evaluation report (SER) (ADAMS Accession No.
ML15331A309) for this rulemaking, were beyond the scope of this
rulemaking, or were already addressed in a previous rulemaking. The NRC
did not make any changes to the direct final rule as a result of the
public comments. However, in Section II, ``Public Comment Analysis,''
of this document, the NRC is taking this opportunity to respond to the
comments in an effort to clarify information about the 10 CFR part 72
CoC rulemaking process.
II. Public Comment Analysis
For rulemakings amending or revising a CoC, the scope of the
rulemaking is limited to the specific changes in the applicant's
request for the amendment or amendment revision. Therefore, comments
about the system or spent fuel storage in general that are not
applicable to the changes requested are outside the scope of this
rulemaking. Comments about details of the particular system subject to
the rulemaking that do not address the rulemaking's specific proposed
changes have already been resolved in prior rulemakings. Persons who
have concerns about prior rulemakings and the resulting final rules may
consider the NRC's process for petitions for rulemaking under 10 CFR
2.802. Additionally, safety concerns about any NRC-regulated activity
may be reported to the NRC in accordance with the guidance posted on
the NRC's Web site at http://www.nrc.gov/about-nrc/regulatory/allegations/safety-concern.html. This Web page provides information on
how to notify the NRC of emergency or non-emergency issues.
The following paragraphs summarize each individual comment followed
by the NRC response.
Comment 1: Noting that this is Holtec's tenth request to amend CoC
No. 1014 for the HI-STORM 100 Cask System, one commenter stated that
many people find this pattern disturbing. The nine earlier amendments
and revisions to CoC No. 1014 suggest that Holtec's overall performance
in achieving technical accuracy has been poor, not only in the
originally-submitted TSs and quality assurance (QA) for this cask, but
in the nine subsequent amendments and revisions that the NRC has
approved. Because this is Holtec's tenth amendment, this commenter
asserted that Holtec has failed to address the full range of the cask's
technical deficiencies comprehensively, and appears instead to have
applied the needed QA only in incremental steps.
NRC Response: This comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. The NRC is providing a specific
response, however, to clarify the NRC's process for issuing and
amending CoCs for dry storage system (DSS) casks.
When the NRC first approves a CoC for a particular storage cask
design, the CoC is based on a postulated generic spent fuel design
using a composite of fuel characteristics and engineered features of
the DSS. Important fuel characteristics include the level of the
uranium enrichment in the fuel pellets and their burnup time in the
reactor. Fuel assembly variables include the composition of the alloys
used in the fuel cladding and assembly hardware; the diameter, number,
and length of the fuel rods; and the spacing between them. These fuel
characteristics and assembly design variables affect the overall heat
load that the cask and multipurpose canister (MPC) holding the fuel
assemblies inside the cask must be able to withstand, with a
conservative margin of safety, to maintain their integrity for long-
term storage under normal, off-normal, and accident conditions. The
residual heat and level of uranium burnup in the spent fuel, and the
spacing of the fuel in the assemblies, in turn affect the number of
fuel assemblies that can be loaded into the MPC, which must have
internal components tailored to maintain the configuration of the fuel
in the canister. Burnup also affects the composition and physical
configuration of the neutron-absorbing materials arranged around the
assemblies within the MPC. Each of these considerations must be
evaluated with each fuel design to ensure the long-term performance of
the overall cask system with an adequate margin of safety.
Fuel and fuel assembly designs have evolved since each storage cask
design was originally certified by the NRC. Contemporary fuel assembly
designs now differ in several important respects from the generic
designs postulated for the casks' original CoCs. To save costs and
reduce worker exposures to radiation, for example, many contemporary
assembly designs are optimized for fuel with higher enrichment levels
to stay in the reactor's core to ``burn,'' or fission, a larger
fraction of uranium for a longer period. This produces fewer spent fuel
assemblies per unit of power generated. It also stretches out the time
between re-fuelings, when workers need to remove the reactor's head to
load new fuel assemblies, off-load used ones, and rearrange partially-
burned assemblies to maintain the efficiency of the overall fuel burnup
within the reactor core. To accommodate the changes in fuel enrichment,
fuel cladding materials, and fuel assembly materials and
configurations, a similar evolution is continuing in MPC componentry,
including neutron-absorbing alloys and other materials, so that casks
can safely accept evolving fuel designs.
Therefore, the nine amendments to CoC No. 1014, like amendments to
other CoCs, each represent an NRC safety finding about the vendor's
analysis of proposed measures to adapt the cask to a new fuel design
for long-term storage. The nine amendments, and the tenth issued in May
2016, are not the product of trial and error, nor of the incremental
application of QA, which must be applied in a safety-graded fashion to
all aspects of cask design, fabrication, loading, and deployment.
The NRC made no changes to the rule as a result of this comment.
Comment 2: One commenter asserted that in the absence of actual
evidence
[[Page 70006]]
from operational experience or testing, using computer models to
estimate a system's behavior or performance has produced ``extreme
failures'' and ``major departures between [the computer model's]
predictions and [the system's] actual performance.'' These departures,
the commenter stated, resulted in a January 2012, radiation release at
San Onofre Nuclear Generating Station's (SONGS) Unit 2 that eventually
led to its premature retirement.
NRC Response: This comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. The commenter does not identify an
issue related to any of the specific revisions proposed in Amendment
No. 10 to CoC No. 1014. Instead, this comment is about a reactor
licensee's computer models for the performance of a reactor system, not
the cask vendor's models for the performance of the HI-STORM 100 Cask
System at issue in this rulemaking. Different types of computer models
are typically validated using different methods. The NRC uses industry
accepted practices to evaluate an applicant's computational modeling
software for storage casks in accordance with Interim Staff Guidance
SFST-ISG-21, ``Use of Computational Modeling Software'' (ADAMS
Accession No. ML061080669). Because Amendment No. 10 does not involve
computational modeling for reactor systems, the comment is not within
the scope of this rulemaking.
As the commenter pointed out, there was a radiation release to the
environment at SONGS in January 2012. This comment too is about an
issue beyond the scope of this rulemaking. The commenter can obtain
more information about the release, which was well below allowable
limits, in Southern California Edison's (SCE) report to the NRC on the
incident (ADAMS Accession No. ML12090A153), and a report by the NRC
Office of the Inspector General (ADAMS Accession No. ML14276A478).
The NRC made no changes to the rule as a result of this comment.
Comment 3: One commenter stated that the proposed CoC amendment
pertains to the same or similar Holtec cask as that to be installed at
SONGS, and southern California stakeholders are ``extremely
disappointed'' that SONGS' licensee, SCE, has chosen Holtec's \5/8\''
thin metal cask over 14''-to-20'' thick casks that the commenter stated
can be inspected in real time to monitor the condition of the spent
fuel and measure the depth of stress corrosion cracking.
NRC Response: This comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. The commenter does not identify an
issue related to any of the specific revisions proposed in Amendment
No. 10 to CoC No. 1014, and this rulemaking does not concern SCE's
choice of cask products. In addition, the NRC has not approved any
spent fuel dry storage cask design that permits the continuous real
time inspection or monitoring of the condition of the fuel in the cask,
or the continuous or periodic direct measurement of the extent or depth
of stress corrosion cracking. Such inspection, monitoring, and
measurement cannot be accomplished without the additional worker
radiation exposures that would be necessary to open the cask overpack
and canister. The NRC's regulation at 10 CFR 20.1101(b), however,
requires radiation doses to workers and members of the public to be as
low as is reasonably achievable. This makes such additional exposures
to open casks and overpacks difficult to justify in light of the very
slow rates of degradation in the cask system and its contents that have
been measured under realistic conditions in a laboratory.
The commenter's description of Holtec's product as a ``\5/8\'' thin
metal cask,'' however, compels a response for clarification purposes.
The comment appears to conflate the MPC, which is not a cask, with the
entirety of the HI-STORM dry cask storage system. The HI-STORM 100 MPC,
which has \1/2\'' thick stainless steel walls, holds the spent fuel
assemblies and their hardware within an overpack. The overpack consists
of outer and inner steel walls with the annulus between them filled
with concrete. The overpack, with 29\1/2\'' thick concrete and steel
walls, provides radiation shielding and mass for stability against such
natural phenomena as winds, floods, and earthquakes. The MPC, an
internal component of the cask system, is not directly exposed to these
outside phenomena.
The NRC made no changes to the rule as a result of this comment.
Comment 4: One commenter stated that the NRC has ``mostly
`dismissed' multiple credible public safety concerns.'' The commenter
also noted that SCE's ``Community Engagement Panel'' has failed to
function as an independent advisory panel of experts, and instead
``functions more as a promotional extension of [SCE's] marketing and
media platforms.''
NRC Response: These comments are not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. The commenter did not identify any of
the ``multiple credible public safety concerns'' that the NRC is said
to have dismissed. Nor did the commenter explain how any of these
concerns pertain to any specific revision proposed in Amendment No. 10
to CoC No. 1014.
The NRC made no changes to the rule as a result of these comments.
Comment 5: One commenter asserted that many stakeholders believe
that the NRC has allowed ``a utility to improperly apply credit for
performing an `educational' function'' that has involved, among other
things, ``extensive private meetings with elected officials in adjacent
communities in San Diego and Orange County.''
NRC Response: The comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. In addition, the NRC's safety-focused
mission does not include authority to allow or prohibit a licensee from
engaging in public relations activities, which do not directly relate
to the design, fabrication, configuration, loading, or deployment of
the dry cask storage system at issue here.
The NRC made no changes to the rule as a result of this comment.
Comment 6: A commenter stated that many stakeholders are asserting
that SONGS licensee, SCE, ``consistently underestimates'' the actual
extent of potential public safety risks associated with its
decommissioning plan.
NRC Response: The comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. The SCE's decommissioning plan does
not pertain to the specific revisions proposed in Amendment No. 10 to
CoC No. 1014; nor does the comment identify any specific potential
public safety risks pertinent to the other purposes of this amendment.
The NRC has a safety hotline that members of the public can use to
report any identified public safety risk, such as may be associated
with any decommissioning action. The hotline number is 1-800-695-7403.
Note that a call during normal business hours (7:00 a.m. to 5:00 p.m.,
Eastern Time) will automatically be directed to the NRC Regional Office
for the caller's geographical area. If the call is placed after normal
business hours, or can't be
[[Page 70007]]
answered by the Regional Office during its normal business hours, the
call will be directed to the NRC's Headquarters Operations Center,
which is staffed 24 hours a day and has a recorded telephone line.
The NRC made no changes to the rule as a result of this comment.
Comment 7: A commenter stated that the licensee expecting to
acquire the Holtec casks subject to Amendment No. 10 for spent fuel
storage at SONGS has ``severely overestimated performance capabilities
of equipment, components and parts, defense in depth, operator
training, emergency response capability, system reliability, cost
containment, and technical capability to safely implement Aging
Management Programs.''
NRC Response: The comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. As noted in the response to Comment
6, the NRC has a safety hotline that members of the public can use to
report any identified public safety risk.
The NRC made no changes to the rule as a result of this comment.
Comment 8: Noting the ``large inventory'' of high-burnup fuel (HBF)
in storage at SONGS, a commenter stated that stakeholders have
``extreme safety concerns'' about the accuracy of the predicted service
life of the Holtec underground maximum capacity (UMAX) casks containing
HBF, which typically has higher heat loads and radiation levels. Among
these concerns, the commenter explained, are ``thermal tolerance
variability, measurement of air velocity, modeling of heat load
distribution, performance capability and integrity of fuel cladding.''
This commenter also stated that with the applicant's proposed
changes in the composition of alloy material in MPC componentry,
stakeholders have concerns about the accuracy of predicted helium
pressure limits for the MPC in underground installations where closed
loop forced helium dehydration (FHD) is mandatory for drying MPCs with
one or more HBF assemblies or a higher heat load.
NRC Response: The comment about HBF storage at SONGS is not within
the scope of this rulemaking, which is limited to the specific
revisions proposed in Amendment No. 10 to CoC No. 1014. None of these
revisions included a change in spent fuel burnup specifications. The
comment is about the HI-STORM UMAX Canister Storage system, which was
authorized generically for underground emplacement under CoC No. 1040
and approved on March 6, 2015 (80 FR 12073). The SONGS will be
utilizing cask systems specified by Amendment No. 1 to CoC No. 1040,
not Amendment No. 10 to CoC No. 1014.
The commenter also expressed concerns about the accuracy of
predicted helium pressure limits for the MPC where closed loop forced
FHD is mandatory for drying MPCs with one or more HBF assemblies or a
higher heat load. The comment does not explain the basis for the
commenter's concern about the predicted pressure limit for drying. This
limit was established to provide an ample safety margin against both
inadequate pressure for thorough drying and excessive pressure that
could result in damage to the spent fuel or other hardware. To maintain
this margin, helium pressure limits are controlled during FHD
operations at all times. During FHD drying, the MPC's inlet (drain
port) and exit (vent port) each have calibrated pressure-indicating
devices that show inlet and outlet pressure during drying operations.
Trained operators use the helium regulator in accordance with the
site's procedures to ensure that the 75-psi limit is not exceeded.
The NRC made no changes to the rule as a result of this comment.
Comment 9: One stakeholder stated that despite Holtec's unproven
assurances about the performance capabilities of its casks, a 2015
Sandia National Laboratory report contained evidence that similar thin-
metal casks had through-wall cracks in only 5 years.
NRC Response: The comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. The Sandia National Laboratory report
referred to by the commenter was for a set of design specifications for
a Standardized Transportation, Aging, and Disposal (STAD) canister for
eventual emplacement in a geologic repository (ADAMS Accession No.
ML16132A321). The NRC could find nothing in this report to support the
commenter's assertion that it ``contained evidence that similar thin
metal casks had through-wall cracks in only 5 years.''
The NRC made no changes to the rule as a result of this comment.
Comment 10: As evidence that Holtec casks are ``an inferior
choice'' for spent fuel storage, one commenter, speaking for
``stakeholders in California,'' referred the NRC to the Web site
``sanonofresafety.org.''
NRC Response: The comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014 and does not concern SCE's choice of
cask products. Beyond the issue of SCE's choice, if the commenter has
concerns about prior spent fuel storage cask rulemakings, or other
issues beyond the scope of this rulemaking that make Holtec casks ``an
inferior choice,'' the commenter may consider the NRC's process for
petitions for rulemaking under 10 CFR 2.802. Additionally, safety
concerns about any NRC-regulated activity may be reported to the NRC in
accordance with the guidance posted on the NRC's Web site at http://www.nrc.gov/about-nrc/regulatory/allegations/safety-concern.html. This
Web page provides information on how to notify the NRC of emergency or
non-emergency issues.
The NRC made no changes to the rule as a result of this comment.
Comment 11: One commenter criticized the NRC for giving in to
Holtec's corporate lawyers and failing to hold the company responsible
for ``creating inadequate safety measures within this [cask] design.''
The commenter exhorted the NRC to ``stop paying for fraud'' and force
Holtec to ``spend [its] own treasure . . ., not tax dollars,'' to fix
the problem.
NRC Response: This comment does not provide sufficient information
to identify the ``inadequate safety measures'' in the Holtec cask's
design that the commenter has in mind. With respect to the concern
regarding payment for the NRC's review and oversight, these functions
are not performed at taxpayers' expense. The vendor, in this case
Holtec, pays for the NRC's evaluation of the application, as the NRC
bills the vendor for the review.
The NRC made no changes to the rule as a result of this comment.
Comment 12: A commenter expressed concern that in permitting a cask
system to accept additional classes of spent fuel, the NRC does not
decrease the ability of these storage systems to contain the fuel under
adverse conditions. The commenter wanted to know whether current
requirements for the durability of spent fuel storage systems are
sufficient to contain these additional fuels, whatever they may be, in
the event of a disaster.
NRC Response: The general issue of the durability of spent fuel
storage systems to contain additional types of spent fuel in the event
of a disaster is not within the scope of this rulemaking, which is
limited to the specific revisions proposed in Amendment No. 10 to CoC
No. 1014. The NRC is addressing the commenter's concern, however, for
educational and clarification purposes.
The NRC addressed a similar comment about the ability of HI-
[[Page 70008]]
STORM UMAX Canister Storage Systems to withstand seismic events during
the CoC No. 1040 certification rulemaking. It should be noted that the
certification provided by approval of the HI-STORM 100 Cask System does
not, in and of itself, authorize the use of this system at any specific
site. Under 10 CFR 72.212(b)(5), before applying the changes authorized
by an amended CoC and loading a cask, a general licensee wishing to use
this cask system must perform written evaluations in accordance with 10
CFR 72.212 to establish, among other things, that:
Cask storage pads and areas have been designed to
adequately support the static and dynamic loads of the stored casks,
considering potential amplification of earthquakes through soil-
structure interaction, and soil liquefaction potential or other soil
instability due to vibratory ground motion; and
The independent spent fuel storage installation at the
reactor site where the casks will be located will meet the requirements
of 10 CFR 72.104 to ensure that radiation doses beyond the reactor's
controlled area do not exceed 0.25 mSv (25 mrem) to the whole body,
0.75 mSv (75 mrem) to the thyroid, and 0.25 mSv (25 mrem) to any other
critical organ, and are further controlled to a level as low as is
reasonably achievable.
The seismic design levels of the HI-STORM 100 Cask System CoC are
acceptable for most areas in the continental United States. For
locations with potential for seismic activity beyond those analyzed for
this system, additional NRC evaluations and certifications may be
required before the system may be used in those locations.
Similarly, although the design levels of the HI-STORM 100 Cask
System CoC for flooding are also acceptable for most areas in the
continental United States--again depending on site-specific analyses--
the NRC staff previously evaluated the impacts of flooding during the
review of the initial certification for the HI-STORM Flood/Wind (FW)
System. In its March 28, 2011, SER for the initial certification of the
HI-STORM FW MPC Storage System (see Sections 4.8.2 and 7.3.1 of ADAMS
Accession No. ML103020151), the NRC staff considered both full and
partial flooding for both the vertical and horizontal positions for the
MPC. The NRC staff found that the fully flooded condition would produce
the highest reactivity in the spent fuel, and that the fully flooded
model for safety evaluations ``is acceptable and applicable to all of
the assembly configurations that are to be stored in the HI-STORM FW
MPC Storage system,'' including damaged fuel configurations. In its
March 28, 2011, SER, the NRC staff also noted the system's design
measures to limit the rise in fuel cladding temperature under the most
adverse flood event (one with a water level just high enough to block
the MPC overpack's air convection inlet duct). The changes requested in
Amendment No. 10 to CoC No. 1014 do not affect the NRC's prior flooding
evaluation for the initial certification of this system.
In addition, under 10 CFR 72.212(b)(6), before using the general
license, the reactor licensee must review the Safety Analysis Report
(SAR) referenced in the CoC or amended CoC and the NRC's SER evaluating
the SAR to determine whether the reactor site parameters, including
analyses of earthquake intensity, tornado missiles, and flooding, are
enveloped by the cask design bases considered in these reports. Like
those for seismic activity, the flooding and tornado missile design
levels of the HI-STORM 100 Cask System CoC are acceptable for most
areas in the continental United States. For locations with potential
for flooding or tornado activity beyond those analyzed for this system,
additional NRC evaluations and certifications may be required before
the system may be used in those locations.
Therefore, the ability of a particular cask system to protect
additional spent fuel types against postulated natural disasters is
required to be subject to rigorous analyses, both generic and site-
specific, before the fuel can be loaded at any given site. If the
design basis of the HI-STORM 100 Cask System CoC No. 1014, Amendment
No. 10, cannot be shown to envelop a particular site's parameters,
Holtec or another vendor would need to obtain NRC certification for
another system meeting the design specifications of the subject spent
fuel before it could be loaded for dry storage.
The NRC made no changes to the rule as a result of this comment.
Comment 13: One commenter suggested that the NRC was in collusion
with the licensee and cited an email exchange between the licensee and
a member of the NRC staff as evidence of such collusion.
NRC Response: The NRC disagrees with the comment. In its capacity
as a regulator, the NRC regularly engages in discussions with licensees
and applicants to facilitate a mutual understanding of the need for any
licensing action, as well as the scope and intent of the licensing
action. The NRC strives to make as much information as possible,
including these interactions, publicly available whenever possible
except where legal obligations dictate otherwise, such as for
proprietary or security-related sensitive information. (see NRC
Management Directive 3.4, ``Release of Information to the Public''
(ADAMS Accession No. ML080310417)). The email exchange cited by the
commenter, which is a publicly available document in ADAMS, is one such
example of this type of discussion. The NRC grounds its licensing
actions on thorough and documented reviews of technical documents that
enable the NRC to reach findings that public health and safety, as well
as the common defense and security, will be adequately protected.
The NRC made no changes to the rule as a result of this comment.
Comment 14: One commenter objected to the use of a newer American
Society of Mechanical Engineers (ASME) code standard for the manganese
content in a carbon steel alloy used in some components of the cask
system and one commenter asserted that at the 1.5 percent manganese
content in the proposed standard, the steel becomes brittle.
Furthermore, the commenter contended, these standards are not specific
to the nuclear industry, and cannot compensate for poor design.
Therefore, the alloy formula must be tested and specific for this
particular design and nuclear spent fuel use.
NRC Response: The NRC disagrees with these comments, and has
provided its detailed assessment in the preliminary SER for Amendment
No. 10 to CoC No. 1014 (ADAMS Accession No. ML15331A309). The minor
change in manganese and carbon content of the proposed alloy has been
endorsed by the ASME. This endorsement provides a high level of
confidence in the quality and safety of the material for nuclear as
well as non-nuclear applications. Any change in an ASME standard must
be documented by rigorous testing under carefully controlled
conditions. Based on this extensive and peer-reviewed testing, the fact
that there is no change to the properties used in the original
technical basis for the HI-STORM 100 Cask System CoC, and the fact that
none of the safety analyses for this CoC are affected by the minor
change in manganese content, the NRC believes that further testing for
this specific application is unnecessary.
The proposed increase in manganese content from 1.2 percent to 1.5
percent maintains, if not improves, the toughness properties of the SA-
516 Grade 70 steel used in the HI-STORM 100 Cask System overpack. The
NRC's preliminary SER for Amendment No. 10 to CoC No. 1014 analyzed
this proposed
[[Page 70009]]
amendment and related Holtec documents and found that there is no
change to the material strength, material density, or thermal
properties of the SA-516 alloy steel, as indicated in the ASME 2007 and
2010 codes. In order to use the alloy approved in the updated 2007-2010
ASME codes, Holtec was required to request an amendment to use these
codes for this alloy because the original HI-STORM 100 Cask System CoC
references only the 1995-1997 ASME codes.
The NRC made no changes to the rule as a result of this comment.
Comment 15: A commenter stated that concrete temperature should be
properly measured on a continuous basis. The same commenter also stated
that each cask should be tested due to possible defects or damage
during loading, as well as differences in the types and ages of spent
fuel. Because conditions change over time, monitoring should be
constant.
NRC Response: The comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. The NRC agrees that concrete
temperatures are important and should be properly measured, but
disagrees that continuous measurement of these temperatures and
constant monitoring are needed. Continuous measurement and constant
monitoring of temperatures are unnecessary in an operating environment
of very gradual temperature changes. Revision 1 of NUREG-1536,
``Standard Review Plan for Spent Fuel Dry Storage Systems at a General
License Facility'' (ADAMS Accession No. ML101040620), notes that for
storage systems with internal air flow passages, the NRC has accepted
periodic visual inspection of vents coupled with temperature
measurements to verify proper thermal performance and detect flow
blockages. The inspections are to take place within an interval that
will allow sufficient time for corrective actions to be taken before
the limiting accident temperature for spent fuel cladding is reached.
The inspection interval should be more frequent than the time interval
required for the fuel to heat up to the established accident
temperature criteria, assuming a total blockage of all inlets and
outlets.
The NRC made no changes to the rule as a result of this comment.
Comment 16: A commenter contended that all airflow and temperature
measurements should be made ``constantly . . . not one time only,'' and
performed ``on intake and output and within the annulus and with an up
to date measurement device and not an antiquated anemometer.''
NRC Response: The NRC disagrees with these comments. The NRC
evaluated the proposed conditions for airflow and temperature
measurements in its final SER (ADAMS Accession No. ML003711865) for the
initial issuance of CoC No. 1014 in 2000, and did not find that
constant temperature measurements were necessary. That SER noted that
in addition to the mandatory initial air temperature rise test when the
system is first placed in service, the overpack air inlet and outlet
vents would be periodically surveyed or an optional overpack air
temperature program would be implemented to verify continued
operability of the heat removal system. Operating experience with this
cask system since that time has given the NRC no reason to change its
initial position on the need for constant temperature measurement.
Concerning the commenter's statement about the need for an up-to-
date measurement device, the NRC has not specifically required the use
of hot-wire anemometer or any other airflow measurement technology. The
applicant may propose the use of any technology it believes will
measure airflow with sufficient accuracy and reliability. The NRC is
not aware of any basis to prohibit the use of hot-wire anemometer
technology for measuring airflow or temperature.
The NRC made no changes to the rule as a result of these comments.
Comment 17: The same commenter that provided Comment 16 objected
that Holtec and the NRC did not provide adequate information on ``other
topics,'' and that this must be presumed to diminish the safety of the
``flimsy'' Holtec cask system.
NRC Response: The commenter did not specify any grounds for
pronouncing the HI-STORM 100 Cask System flimsy, or any ``other
topics'' for which additional information might be considered adequate.
The NRC made no changes to the rule as a result of this comment.
Comment 18: A commenter contended that ``measurements are not
supposed to validate methods outside of experiments testing theory,''
and that the requirement to ``demonstrate'' an airflow model with
measurements implies ``fraudulent'' intent to ``play with numbers to
get what [NRC] and/or Holtec want'' to show the safety of the storage
cask system.
NRC Response: These comments are not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. The NRC also disagrees with these
comments. The NRC does not require measurements to validate methods
that cannot be tested experimentally. The commenter particularly
disapproved of a draft NRC requirement in an email to Holtec (ADAMS
Accession No. ML15327A043) in which users of the HI-STORM 100 Cask
System would be required to perform a ``thermal validation test'' to
measure the total air mass flow rate through the cask system using
direct measurements of air velocity in the inlet vents. The user would
then be required to do an analysis of the cask system with these
measurements ``to demonstrate that the measurements validate the
analytic methods'' described in Chapter 4 of Holtec's Final Safety
Analysis Report (ADAMS Accession No. ML14086A412), supporting its
application for CoC No. 1014. The NRC has reason to require a licensee
to demonstrate that an analytic method for thermal modeling of airflow
through a cask is supported by real-world measurements. In making this
demonstration, a licensee could ``play with numbers'' if it were
allowed to measure anywhere it chose, but that is not the case here.
The licensee is required to take measurements at NRC-specified
locations.
The NRC made no changes to the rule as a result of these comments.
Comment 19: Citing NRC regulations at 10 CFR 72.236, ``Specific
requirements for spent fuel storage cask approval and fabrication,''
one commenter alleged that Holtec violated U.S. law because ``the only
protection from lethal radiation leaks is the \1/2\ inch MPC, whereas
`The spent fuel storage cask must be designed to provide redundant
sealing of confinement systems.' ''
NRC Response: The comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. The NRC also disagrees with this
comment. The MPC does provide protection from radiation leaks, but it
is not the only protective barrier. Radiation shielding is also
provided by the HI-STORM 100 Cask System overpack that is composed of
inner and outer steel shells with the annulus between them filled with
concrete, which is the primary radiation shielding material. If the
commenter was referring only to leakage of radioactive materials from
the MPC, however, Section 7.1 of the SER (ADAMS Accession No.
ML003711865) for the HI-STORM 100 Cask System confirms the presence of
redundant sealing of confinement systems in the canister's design:
[[Page 70010]]
The [MPC] confinement boundary includes the MPC shell, the bottom
baseplate, the MPC lid (including the vent and drain port cover
plates), the MPC closure ring, and the associated welds. . . . The MPC
lid (with the vent and drain port cover plates welded to the lid) and
closure ring are welded to the upper part of the MPC shell at the
loading site. This provides redundant sealing of the confinement
boundary. . . . The redundant closures of the MPC satisfy the
requirements of 10 CFR 72.236(e) for redundant sealing of confinement
systems.
The MPC's confinement design has multiple related purposes. The
confinement design ensures that potentially contaminated air is
contained within the MPC and that the MPC remains filled with helium
coolant, so that the MPC can fulfill a third purpose: to keep outside
air from contacting the spent nuclear fuel for the licensed life of the
system.
In addition to the redundant barriers to airborne radiation leakage
in the design of the HI-STORM 100 MPC and cask system, there are
procedural requirements to ensure that the system and its components
function in operation as designed. In accordance with the CoC itself
(ADAMS Accession No. ML15331A307), the design, purchase, fabrication,
assembly, inspection, testing, operation, maintenance, repair, and
modification of all structures, systems, and components that are
important to safety, both for the MPC and the system as a whole, must
be conducted in accordance with a Commission-approved quality assurance
program that satisfies the applicable requirements of 10 CFR part 72,
subpart G.
The CoC also requires that when the MPC shell is welded to its
baseplate, the fabricator must perform a helium leak test of the MPC
weld's confinement using a helium mass spectrometer. This weld leakage
test must include the base metals of the MPC shell and baseplate.
Another helium leak test must be performed on the base metal of the
fabricated MPC lid. Then, in the field, a helium leak test must be
performed on the vent and drain port confinement welds and cover plate
base metal before the loaded MPC can be emplaced within the concrete
overpack. All MPC confinement boundary leakage rate tests must be
performed in accordance with ANSI N14.5 to ``leaktight'' criteria. If
the user detects a leakage rate exceeding the acceptance criteria, the
user must determine the area of leakage and repair it to meet ASME Code
Section III, Subsection NB requirements. The affected area must then be
re-tested until the leakage rate acceptance criterion is met.
The NRC made no changes to the rule as a result of this comment.
Comment 20: Citing NRC regulations at 10 CFR 72.236, ``Specific
requirements for spent fuel storage cask approval and fabrication,'' a
commenter asserted that Holtec violated U.S. law also because its
storage cask is not designed to provide adequate heat removal capacity
without active cooling systems, and ``[t]he refusal to properly test
[the cask's heat removal capacity] appears intentional to avoid knowing
if it properly removes heat.''
NRC Response: The comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. The comment also does not explain how
Holtec storage casks are not designed to meet the 10 CFR 72.236
requirement to provide adequate heat removal capacity without active
cooling systems. HI-STORM 100 Cask Systems have been deployed at
independent spent fuel storage installations for more than a decade
without active cooling systems.
The NRC disagrees with the comment. The NRC's preliminary SER
evaluated Holtec's supporting thermal analysis for Amendment No. 10 to
CoC No. 1014 and found that the HI-STORM 100 Cask System certification
``continues to be designed with a heat-removal capability having
verifiability and reliability consistent with its importance to
safety.'' The SER also found that spent fuel cladding continues to be
protected against thermal degradation leading to gross ruptures, and
other cask component temperatures continue to be maintained below the
allowable limits for the accidents evaluated.
There has been no refusal to test the cask system's heat removal
capacity. The CoC language has been revised to require CoC No. 1014,
Amendment No. 10, users to submit thermal validation test and analysis
results in a letter report to the NRC within 180 days of either the
user's loading of the first cask or undertaking the first spent fuel
transfer operation with a cask fabricated to Amendment No. 10
specifications. The revised condition also states, however, that for
casks of the same system type, users may document in their 10 CFR
72.212 report a previously performed test and analysis that has
demonstrated adequate validation of the analytic thermal methods. The
NRC will evaluate whether this previous test and analysis continues to
demonstrate adequate validation of thermal analysis methods in light of
the uncertainty of airflow measurements at the previously-specified
locations.
The NRC made no changes to the rule as a result of this comment.
Comment 21: One commenter stated that the NRC has violated the
Plain Writing Act of 2010 by failing to make the topics associated with
this rulemaking clear, and failing to ``attach . . . the relevant
documents in an orderly, clear manner.''
NRC Response: The NRC disagrees with these comments. The topics
associated with this rulemaking must necessarily address the CoC
amendments requested by the applicant, and these are by nature highly
technical. The March 14, 2016 (81 FR 13265), Federal Register notice of
the direct final rule does, however, seek to explain in language as
non-technical as possible the practical effects of the amendment
requests for the use of the Holtec HI-STORM 100 Cask System under
Amendment No. 10 of CoC No. 1014. In general, the NRC strives to write
agency documents in a clear, concise, well-organized manner that also
follows other best practices appropriate to the subject and the
intended audience.
As to the comment that documents relevant to this rulemaking were
not ``attached . . . in an orderly, clear manner,'' the NRC followed
its normal process of providing the ADAMS accession numbers to
referenced documents so that interested persons may obtain access to
the documents. If the commenter was referring instead to the table of
references provided in the Federal Register notice for the direct final
rule, the NRC also disagrees that the relevant documents were not
presented in an orderly, clear manner. The order of the references
starts with the applicant's amendment request, moves to the proposed
revised CoC and TS documents supporting it, and concludes with the
NRC's response to these submittals in the form of its SER on the
proposed revisions.
The NRC made no changes to the rule as a result of these comments.
Comment 22: One commenter stated that the percentage of the NRC's
budget that must be recovered should be recovered in fines and not
fees.
NRC Response: The comment is not within the scope of this
rulemaking, which is limited to the specific revisions proposed in
Amendment No. 10 to CoC No. 1014. Under the Omnibus Budget
Reconciliation Act of 1990, as amended, the NRC is required by law to
recover 90 percent of its budget through fees for licensing and other
actions. Therefore, any change in this requirement can only be achieved
by an act of Congress.
[[Page 70011]]
The NRC made no changes to the rule as a result of this comment.
In summary, the NRC did not receive any comments that warranted
withdrawal of the direct final rule. Therefore, none of these comments
required a change in the rule's effective date of May 31, 2016.
Dated at Rockville, Maryland, this 28th day of September, 2016
For the Nuclear Regulatory Commission.
Michael R. Johnson,
Acting Executive Director for Operations.
[FR Doc. 2016-24466 Filed 10-7-16; 8:45 am]
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