FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

PUBLIC CITIZEN; SAN LUIS OBISPO 

MOTHERS FOR PEACE,

No. 07-71868 Petitioners,  NRC No. v.

10CFR

NUCLEAR REGULATORY COMMISSION,

Respondent. 

STATE OF NEW YORK, 

Petitioner, No. 07-72555

v. NRC No.  07-2052 NUCLEAR REGULATORY COMMISSION;

UNITED STATES OF AMERICA, OPINION

Respondents. 

On Petition for Review of an Order of the

Nuclear Regulatory Commission

Argued and Submitted

November 17, 2008—San Francisco, California

Filed July 24, 2009

Before: Cynthia Holcomb Hall, Thomas G. Nelson and

Sidney R. Thomas, Circuit Judges.

Opinion by Judge Hall;

Partial Concurrence and Partial Dissent by Judge Thomas

9615
COUNSEL

Adina H. Rosenbaum, Public Citizen Litigation Group, Washington, D.C., for the petitioners.

John J. Sipos, Assistant Attorney General, Albany, New

York, for the petitioner.

Steven F. Crockett, Special Counsel, Karen D. Cyr, General

Counsel, John F. Cordes, Jr., Solicitor, and E. Leo Slaggie,

Deputy Solicitor, United States Nuclear Regulatory Commission, Washington, D.C.; Ronald J. Tenpas, Assistant Attorney

General, Ronald M. Spritzer, Environment and Natural

Resources Division, United States Department of Justice,

Washington, D.C., for the respondents.

David A. Repka, Winston & Strawn, Washington, D.C., for

the intervenor-respondent.

Brian Hembacher, Deputy Attorney General, State of California, Los Angeles, California, for the amici curiae.

OPINION

HALL, Senior Circuit Judge:

Petitioners Public Citizen, Inc., San Luis Obispo Mothers

For Peace, the State of New York,1 and amicus State of Cali1New York’s petition for review was properly transferred to this court

and consolidated with the petition of Public Citizen pursuant to 28 U.S.C.

§ 2112(a)(5). 

PUBLIC CITIZEN v. NRC 9619
fornia (“Petitioners”) challenge the Nuclear Regulatory Commission’s (“NRC” or “Commission”) modification of the

Design Basis Threat (“DBT”) rule and partial denial of the

Committee to Bridge the Gap’s (“CBG”) petition for rulemaking. Petitioners claim the Commission acted arbitrarily and

capriciously and contrary to law by refusing to include the

threat of air attacks in the final revised DBT rule. Petitioners

also claim NRC violated the National Environmental Policy

Act (“NEPA”) by not considering the risk of an airborne terrorist attack in its Environmental Assessment (“EA”), and that

this risk creates a potentially significant impact on the environment necessitating a full Environmental Impact Statement

(“EIS”). We deny the petition.

I. Background

A. The History of the Commission and Development of the

“Adequate Protection” Standard

To better understand the complicated history of the DBT

Rule, we first outline the role of the NRC itself. In 1954, Congress passed the Atomic Energy Act (“Act”). 42 U.S.C.

§ 2011 et seq. The Act created the Atomic Energy Commission, later renamed the Nuclear Regulatory Commission, to

regulate and develop the use of atomic energy. The Act is

“virtually unique in the degree to which broad responsibility

is reposed in the administrative agency, free of close prescription in its charter as to how it shall proceed in achieving the

statutory objectives.” Siegel v. Atomic Energy Commission,

400 F.2d 778, 783 (D.C. Cir. 1968). 

When licensing nuclear facilities, the Commission is

charged with ensuring that the operation of those facilities is

“in accord with the common defense and security and will

provide adequate protection to the health and safety of the

public.” 42 U.S.C. § 2232(a). Although “adequate protection”

is not defined in the statute, legislative history “indicate[s]

that the Congressional concern with the common defense and

9620 PUBLIC CITIZEN v. NRC
security related to such matters as the safeguarding of special

nuclear material; the absence of foreign control over the

applicant; the protection of Restricted Data; and the availability of special nuclear material for defense needs.” Siegel, 400

F.2d at 781 (internal quotations omitted). “The public health

and safety standard, in like fashion, was said to be addressed

to the overall qualifications of the applicant and the design of

the facility to protect plant employees and the public against

accidents and their consequences.” Id. at 781-782 (internal

quotations omitted). 

The adequate protection standard has also acquired meaning through subsequent case law. Union of Concerned Scientists v. NRC, 824 F.2d 108, 117 (D.C. Cir. 1987) (Concerned

Scientists I), held that while the Commission could not consider costs in determining the level of adequate protection

necessary, it could consider other factors, including the nature

and extent of the risks involved. The court declined to establish the scope of those factors, however, instead concluding

that “the ‘adequate protection’ standard may be given content

through case-by-case application of [the Commission’s] technical judgment rather than by a mechanical verbal formula or

set of objective standards” set by either NRC or an interpreting court. Union of Concerned Scientists v. NRC, 880 F.2d

552, 558 (D.C. Cir. 1989) (Concerned Scientists II). 

Concerned Scientists I also made clear that “adequate protection” does not mean “absolute protection,” and that the

standard “permits the acceptance of some level of risk.” 824

F.2d at 114, 118. “Safe is not the equivalent of risk-free.” Id.

at 118 (internal quotations omitted). The Commission is

authorized to impose additional safety measures on licensees

above those required by adequate protection, and in doing so

may consider the economic costs of those extra measures. Id.

Siegel v. Atomic Energy Commission was the first case to

challenge whether adequate protection should extend beyond

the original congressional concerns to also encompass “the

risk of an enemy attack or sabotage against [the] structures.”

PUBLIC CITIZEN v. NRC 9621
400 F.2d at 783-784. The Siegel court held that there was no

indication that the “Commission was commanded to intrude

the possibility of enemy action into the concepts of ‘the common defense and security’ and ‘the public health and safety.’ ” Id. 

The Siegel case dealt with the Commission’s decision

declining to require licensees to protect against possible missile attacks on nuclear facilities near Cuba. The court upheld

the Commission’s newly created “Enemy of the State” rule,

which insulated licensees from the requirement that they protect against the effects of attacks or destructive acts by enemies of the United States (foreign governments or other

persons) or that they use or deploy weapons incident to U.S.

defense activities. 10 C.F.R. § 50.13. The court favorably

cited the Commission’s rationale animating the Enemy of the

State rule: “that [requiring] reactor design features to protect

against the full range of the modern arsenal of weapons [is]

simply not practicable and that the defense and internal security capabilities of this country constitute, of necessity, the

basic ‘safeguards’ as respects possible hostile acts by an

enemy of the United States . . . . [t]he risk of an enemy attack

or sabotage against such structures, like the risk of all other

hostile attacks which might be directed against this country,

is a risk that is shared by the nation as a whole.” Id. at 783.

B. The Origin of the Design Basis Threat Rule

The Commission, wholly of its own accord, decided in

1977 to promulgate the first Design Basis Threat (“DBT”)

rule to protect nuclear power reactors from industrial sabotage. 42 Fed. Reg. 10,836 (Feb. 24, 1977). “Design bases”

are, generally speaking, applicant or licensee information

which identifies the specific functions to be performed by a

structure or system. 10 C.F.R. § 50.2. The “threat” is an

adversary characteristic, or what sort of threat against which

a licensee should be prepared to defend and engage. 72 Fed.

Reg. 12,705, 12,705, 708 (Mar. 19, 2007). The DBT rule

9622 PUBLIC CITIZEN v. NRC
challenged in this action, 10 C.F.R. § 73.1, is the purpose and

scope section which defines included adversary chracteristics.

Other regulations implement specific physical protection

requirements to address these adversary characteristics once

they are included within the scope of the rule. See, e.g., 10

C.F.R. § 73.55 (outlining physical protection requirements to

protect against radiological sabotage). 

The regulation initially protected only against industrial

sabotage by individuals and groups with possible inside information and hand-held weapons. But, the regulation stated:

“[t]he kind and degree of threat and the vulnerabilities to such

threats will continue to be reviewed by the Commission . . . .

the Commission [will] consider changes to meet the changed

conditions.” 42 Fed. Reg. 10,836, 10,836. 

In 1994, the Commission revised the DBT rule in response

to an intrusion at a nuclear power plant, the 1993 vehicle

bomb attack on the World Trade Center, and intelligence that

showed “a conspiracy with ties to the Middle East extremists

clearly demonstrated the capability and motivation to organize, plan, and successfully conduct a major vehicle bomb

attack,” 59 Fed. Reg. 38,889, 38,891 (Aug. 1, 1994). The

revised DBT incorporated the threat of adversaries utilizing “a

four-wheel drive land vehicle used for transporting personnel

and their hand-carried equipment,” and “a four-wheel drive

land vehicle bomb.” Id. The Commission explicitly denied

that these changes were necessary to meet the adequate protection standard. Instead, the changes were issued under the

Commission’s authority to outline additional safety measures

as a “matter of prudence” and represented a “substantial

increase in protection of the public health and safety.” 59 Fed.

Reg. 38,889, 38,891, 896; see also Concerned Scientists I,

824 F.2d at 118. 

To partially implement the 1994 DBT change, the Commission also revised 10 C.F.R. § 73.55 to require the installation

of passive vehicle barriers. These barriers were required to

PUBLIC CITIZEN v. NRC 9623
“protect against vehicle intrusion into protected areas,” but

the Commission believed that, if placed in the correct locations, they could also protect against a vehicle bomb. 59 Fed.

Reg. 38,889, 38,891. Because the changes were permissibly

made to “provide an additional, substantial increase in the

overall protection of the public health and safety,” rather than

statutorily required to meet the adequate protection standard,

the Commission engaged in a cost-benefit analysis of the protective measures. Id.; see also Concerned Scientist I, 824 F.2d

at 118. 

In that cost-benefit analysis, the Commission explicitly

rejected the argument from the nuclear industry that the

Enemy of the State rule insulated them from these measures.

The Commission reasoned “[t]here is a significant difference

in the practicality of defending against a missile attack and

constructing a vehicle barrier,” and that the scope of the

Enemy of the State rule was to “relieve applicants of the need

to provide protective measures that are the assigned responsibility of the nation’s defense establishment.” 59 Fed. Reg.

38,889, 38,893. The Commission further explained that the

Enemy of the State rule “recogniz[es] that it [is] not practical

for the licensees of civilian nuclear power reactors to provide

design features that could protect against the full range of the

modern arsenal of weapons.” Id.

C. Post 9/11 and the Commission’s Response

Following 9/11, the Commission again determined a

change to the DBT rule was necessary. Many studies were

conducted by both private and government entities, independently and at the behest of the NRC, which showed that

nuclear facilities were not designed to withstand the impact of

a commercial jet plane. The studies showed that while “many

of [the] safety-related systems are well protected within hardened structures . . . some are not.” In the worst case, an aircraft crash had the potential to set off an accident sequence

resulting in “serious damage if not total meltdown” of the

9624 PUBLIC CITIZEN v. NRC
core, but such a sequence would “require[ ] the occurrence of

multiple failures, many of which are strongly plantdependent.” Additionally, many intelligence agencies, and the

NRC itself, closely monitored and acknowledged the credible

threat of a terrorist attack on nuclear facilities. 

The Commission responded to this information by issuing

emergency orders to licensees on February 25, 2002, January

7, 2003, and April 29, 2003. These orders, though non-public

and protected as “safeguards information” pursuant to 42

U.S.C. §§ 2167, 2201(i), required licensees to make a wide

variety of security improvements. See 70 Fed. Reg. 67,380,

67,381 (Nov. 7, 2005). Following the implementation of these

orders, the NRC “conducted detailed, site-specific engineering studies of a limited number of plants to gain insights on

[continued] potential vulnerabilities of nuclear power plants

to deliberate attacks involving large commercial aircraft.” 72

Fed. Reg. 12,705, 12,710. For the NRC, these studies “confirmed the effectiveness of the February 2002 NRC-ordered

mitigative measures” and “the low likelihood of both damaging the reactor core and releasing radioactivity that could

affect public health and safety.” Id. The studies also “indicate[d] that there would be time to implement the required onsite mitigating actions” in the “unlikely event” that a terrorist

is able to use a large aircraft against a nuclear facility. Id.

“[A]dditional key radiological protection and mitigation strategies” were imposed by the NRC on appropriate licensees by

order in June 2006. Id.; see also 71 Fed. Reg. 36,554 (June

27, 2006). 

The NRC also increased coordination efforts with other

government agencies. “[I]n early March 2006, the NRC

hosted an Interagency Aircraft Attack Tabletop Exercise at

NRC Headquarters . . . . reconfirm[ing] the respective responsibilities of the participating organizations (NRC, DHS

[Department of Homeland Security], DOD [Department of

Defense], and FBI) in the event of a nuclear plant aircraft

attack and clarif[ying] protocols for response-related interaPUBLIC CITIZEN v. NRC 9625
gency communication and coordination.” 72 Fed. Reg.

12,705, 12,710. The NRC and DHS also “worked together to

develop and improve EP [Emergency Planning] for a terrorist

attack through federal initiatives such as comprehensive

review programs and integrated response planning efforts”

including “State/local/tribal response capabilities.” 72 Fed.

Reg. 12,705, 12,712. Those efforts “include[d] prearranged

plans with local law enforcement and emergency planning

coordination.” 72 Fed. Reg. 12,705, 12,714. 

In June 2004, the Commission announced a proposed

amendment to the DBT rule “to incorporate the Commission

actions taken as a result of September 11, 2001,” making “review and revisions as appropriate.” 69 Fed. Reg. 38,635,

38,636 (June 28, 2004). In July 2004, the Commission

received a rulemaking petition from Committee to Bridge the

Gap, PRM-73-12, which requested, inter alia: amending the

DBT to “encompass attacking forces equal to those of 9/11”

including attacks by boat and by air; amending the DBT

enabling regulations to mandate security plans, systems,

inspections, and force-on-force exercises; and requiring construction of “beamhenge” shields2

 to protect against air attack.3

Finally, as part of the Energy Policy Act of 2005, Congress

directed the Commission to initiate or complete rulemaking to

revise the design basis threats. 42 U.S.C. § 2210e (effective

August 8, 2005). Congress directed the Commission to consider twelve non-exclusive factors in its rulemaking, including

“the potential for water-based and air-based threats.”

§ 2210e(b)(6).4

2The “beamhenge” concept involves a shield constructed of I-beams

with steel or other cabling and netting between them at standoff distances

around key structures at nuclear plants. See http://

www.committeetobridgethegap.org/beamhenge.html. 

3Attorneys General from seven states, including New York, filed written comments in support of the CBG petition in January 2005. 

4The twelve non-exclusive factors the Commission was instructed to

consider are: “(1) the events of September 11, 2001; (2) an assessment of

9626 PUBLIC CITIZEN v. NRC
D. The Current Revised DBT Rule 

The Commission issued the final revised DBT rule in

March 2007. See 72 Fed. Reg. 12,705. The rule significantly

increased the range of threats included within the DBT scope

and incorporated most of the factors Congress listed in

§ 2210e, including attacks by multiple groups attacking

through multiple entry points, individuals willing to kill or be

killed, water vehicles and water-based vehicle bomb assaults,

and cyber attacks. See 10 C.F.R. § 73.1. The final rule discusses: the 2002 and 2003 Orders in general terms, actions

taken by other Federal agencies in the wake of 9/11 to

increase national security and NRC’s efforts to coordinate

responses with these agencies, each of the twelve congressional concerns, public comments received, and the CBG petition. See generally 72 Fed. Reg. 12,705.

The revised DBT rule elaborates on the purpose and scope

of the DBT rule, which the Commission explained was premised upon “adversary characteristics against which a private

security force can reasonably be expected to defend.” 72 Fed.

Reg. 12,705, 12,713. Relying on this “reasonable expectation”

standard, the Commission determined that the threat of an airbased attack was beyond the scope of the DBT rule. The

physical, cyber, biochemical, and other terrorist threats; (3) the potential

for attack on facilities by multiple coordinated teams of a large number of

individuals; (4) the potential for assistance in an attack from several persons employed at the facility; (5) the potential for suicide attacks; (6) the

potential for water-based and air-based threats; (7) the potential for use of

explosive devices of considerable size and other modern weaponry; (8) the

potential for attacks by persons with sophisticated knowledge of facility

operations; (9) the potential for fires, especially fires of long duration; (10)

the potential for attacks on spent fuel shipments by multiple coordinated

teams of a large number of individuals; (11) the adequacy of planning to

protect the public health and safety at and around nuclear facilities, as

appropriate, in the event of a terrorist attack against a nuclear facility; and

(12) the potential for theft and diversion of nuclear materials from such

facilities.” § 2210e. 

PUBLIC CITIZEN v. NRC 9627
Commission reasoned that “the responsibility for actively protecting against the threat lies with other organizations of the

Federal government, as it does for any U.S. commercial infrastructures.” 72 Fed. Reg. 12,705, 12,710 (emphasis added).

The Commission explained that the public health and safety

was adequately protected, however, because of: 1) the active

protection of other Federal agencies, with whom the NRC

continues to coordinate; and 2) mitigative measures implemented by the licensees that would limit the effect of an aircraft strike. 72 Fed. Reg. 12,705, 12,711. Because the NRC

determined both that air-based threats were beyond the scope

of the DBT rule and that the adequate protection standard was

satisfied, CBG’s petition for rulemaking, as it pertained to the

beamhenge concept, was denied. Id.5

As in 1994, the Commission again rejected the argument

that the Enemy of the State rule insulated the industry from

meeting the requirements of the revised DBT rule. The Commission emphasized that “the DBT rule does not focus on the

identity, sponsorship, or nationality of the adversaries,” but

rather a “range of attacks and capabilities” against which pri5The Commission continues to evaluate air-based threats even after the

revised DBT rule. In October 2007, the Commission issued a proposed

rule to amend 10 C.F.R. § 52 (Design Features) with the objective of “requir[ing] nuclear power plant designers to perform a rigorous assessment

of design features that could provide additional inherent protections to

avoid or mitigate, to the extent practicable, the effects of an aircraft

impact, with reduced reliance on operator actions.” 72 Fed. Reg. 56,287

(Oct. 3, 2007) (emphasis added). The NRC issued a press release on February 17, 2009, announcing it had issued its final rule requiring “applicants for new power reactors to assess the ability of their reactor designs

to avoid or mitigate the effects of a large commercial aircraft impact.” See

http://www.nrc.gov/reading-rm/doc-collections/news/2009/09-030.html

(last visited May 15, 2009). The press release reiterates the NRC’s consistent position that the new design features “will result in a margin of safety

far beyond that required to achieve reasonable assurance of public health

and safety,” and that the responsibility of preventing the impact of large

commercial aircraft rests with the federal government as it is a beyonddesign-basis event. Id. (emphasis in original). 

9628 PUBLIC CITIZEN v. NRC
vate facilities can be “reasonably expected to defend . . .

regardless of whether it would or would not be deemed an

‘enemy of the state.’ ” 72 Fed. Reg. 12,705, 12,714-715. 

To comply with NEPA, the Commission completed an EA

for the final rule. Based upon the EA, the Commission concluded that there would be no significant environmental

impact associated with the rule and therefore no EIS was necessary. 72 Fed. Reg. 12,705, 12,718. The Commission also

concluded that NEPA did not require an evaluation of terrorist

attacks as “the consequences of a terrorist attack cannot be

said to be ‘an effect’ of this rule, and analyzing the effects of

a terrorist attack would be speculative at best.” 72 Fed. Reg.

12,705, 12,718-719. The Commission acknowledged this

court’s decision in Mothers for Peace, but distinguished a

licensing decision from the rulemaking action at issue. Id.; see

Mothers for Peace v. NRC, 449 F.3d 1016 (9th Cir. 2006). 

II. Standard of Review 

Under the Administrative Procedure Act (“APA”), agency

decisions may be set aside only if “arbitrary, capricious, an

abuse of discretion, or otherwise not in accordance with law.”

Earth Island Inst. v. U.S. Forest Serv., 442 F.3d 1147, 1156

(9th Cir. 2006) (quoting 5 U.S.C. § 706(2)(A)). “Review

under this standard is narrow, and the reviewing court may

not substitute its judgment for that of the agency.” Id. at 1156.

“We reverse under the arbitrary and capricious standard only

if the agency has relied on factors that Congress has not

intended it to consider, has entirely failed to consider an

important aspect of the problem, or has offered an explanation

for that decision that runs counter to the evidence before the

agency or is so implausible that it could not be ascribed to a

difference in view or the product of agency expertise.” Id. 

“[A]n agency’s interpretation of its own regulations is ‘controlling’ unless ‘plainly erroneous’ or inconsistent with ‘the

regulations being interpreted.’ ” Long Island Care at Home,

PUBLIC CITIZEN v. NRC 9629
Ltd. v. Coke, 127 S. Ct. 2339, 2349 (2007) (citing Bowles v.

Seminole Rock & Sand Co., 325 U.S. 410, 414 (1945)). 

This court is limited to a review of the reasoning the

agency relied upon in making its decision. Safe Air for Everyone v. EPA, 488 F.3d 1088, 1091 (9th Cir. 2007) (citing SEC

v. Chenery Corp., 318 U.S. 80, 87 (1943)). “We will, however, uphold a decision of less than ideal clarity if the agency’s path may reasonably be discerned.” Motor Vehicle Mfrs.

Ass’n v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29, 43

(1983). “Where . . . the agency’s course of action indicates

that the interpretation of its own regulation reflects its considered views [rather than merely post hoc rationalization] . . .

we have accepted that interpretation as the agency’s own,

even if the agency set those views forth in a legal brief.”

Coke, 127 S. Ct. at 2349; see also Global Crossing Telecomm., Inc. v. Metrophones, 127 S. Ct. 1513, 1525 (2007)

(noting that even if agency action is inadequately reasoned

initially, context and history of position can make agency’s

rationale obvious).

III. Discussion 

A. The Scope of the DBT Rule and the Reasonable 

Expectation Standard

Petitioners first argue that the Commission’s explanation of

the scope of the DBT rule—as reaching only those threats

which a private force can reasonably be expected to defend

against—is a new standard which conflicts with and departs

from the Commission’s prior interpretations of the DBT rule,

and therefore represents an abuse of discretion. See, e.g., W.

States Petroleum Ass’n v. EPA, 87 F.3d 280, 285 (9th Cir.

1996). 

[1] Here, however, the Commission is not departing from

an established standard, but is merely elaborating on the interpretation of its own regulation. See Coke, 127 S. Ct. at 2349

9630 PUBLIC CITIZEN v. NRC
(holding that so long as interpretive changes create no unfair

surprise, as when an interpretation is codified in notice-andcomment rulemaking, the agency’s interpretation of its own

regulations is controlling unless plainly erroneous). Though

the scope of the DBT has not previously been precisely defined,6

the NRC’s decisions have clearly been animated by considerations of the credibility of the threat at issue and whether private forces can reasonably be expected to actively engage that

threat. This rationale, while not previously articulated in any

one section of the rule, is easily ascertained from the history

and context of the DBT rule. See Global Crossing, 127 S. Ct.

at 1525. 

In both the 1977 and 1994 DBT rules, the Commission

evaluated the “kind and degree of threat” at issue in determining the scope of the DBT, illustrating that a threat must be

credible before it is included. See 42 Fed. Reg. 10,836,

10,836; see also 59 Fed. Reg. 38,889, 38,891. This is also

consistent with NRC’s decision to revise the DBT rule in light

of the changed threat environment created by the events of

9/11. See 72 Fed. Reg. 12,705, 12,705.

In rejecting the Enemy of the State rule in both its 1994 and

2007 revisions when it was “practical” or “reasonable” for

private forces to defend against the included threats, the Commission illustrated that a concept of reasonableness animates

both the DBT and the Enemy of the State rules. See 59 Fed.

Reg. 38,889, 38,893; 72 Fed. Reg. 12,705, 12,714-715; see

also Siegel v. Atomic Energy Commission, 400 F.2d 778, 783

(D.C. Cir. 1968) (noting Commission’s “recognition that reactor design features to protect against the full range of the

modern arsenal of weapons are simply not practicable

. . . .”). Both rules have also been influenced by the reasonable division of nuclear defense responsibilities between pri6The Commission acknowledges a standard has intentionally not been

articulated so as to preserve the Commission’s flexibility. See 72 Fed.

Reg. 12,705, 12,713; see also Concerned Scientists II, 880 F.2d at 558. 

PUBLIC CITIZEN v. NRC 9631
vate and government forces. See Siegel, 400 F.2d at 783

(discussing defense and internal security capabilities in creation of Enemy of the State Rule); 59 Fed. Reg. 38,889,

38,893 (discussing that some protective measures are the

assigned responsibility of the nation’s defense establishment).

Previous adversary characteristics have only been included

within the scope of the DBT rule if they represented a class

of threat that private forces could actively engage, such as

militant individuals or vehicles. See 10 C.F.R. § 73.1. Only

once a threat is determined to be within the scope of the DBT

do the implementing regulations contemplate passive protective measures as supplemental means of defending against the

threats. For instance, 10 C.F.R. § 73.55 required licensees to

install passive barriers to protect against vehicle intrusion

only after vehicle threats were added to the DBT rule. 59 Fed.

Reg. 38,889, 38,891. The NRC determined however, that neither the inclusion of vehicle threats, nor the decision to locate

barriers in a position where they could also maximize protection from vehicle bombs, was required to satisfy the statutory

adequate protection standard. Instead, the Commission illustrated that the requirements of the DBT rule could exceed the

requirements of adequate protection where the Commission

determined that private forces could reasonably defend

against the threat. 

[2] Applying this standard of reasonable expectation, the

agency did not act arbitrarily nor capriciously in concluding

that air-based threats were beyond the scope of the DBT rule.

An airplane attack is different in kind than attacks by militant

individuals or vehicles. Unlike other vehicles, airplanes are

not used as an intrusionary device to gain access to secure

portions of the facility. Instead, an airplane is used as an

explosive weapon, more analogous to a missile. When facing

an attack from a vehicle, a private force can engage those persons who seek to intrude upon the facility. There are no surviving crew members of an airplane for private forces to

engage following impact. Like a missile, the only means of

9632 PUBLIC CITIZEN v. NRC
actively engaging an attack from an airplane is through the

use of anti-aircraft devices (prudently) unavailable to private

security forces. See 72 Fed. Reg. 12,705, 12,710. Thus the

rationale of the Enemy of the State rule applies to air-based

terrorist attacks, in that the defense against these attacks is

best left to government agencies. Once the Commission made

the general determination that air-based threats were outside

the scope of the DBT, the Commission was under no obligation to consider passive protective measures, such as the

beamhenge concept, as part of this rulemaking procedure.7

B. Adequate Protection from Air-Based Threats

[3] Petitioners contend that the NRC’s decision to define

the scope of the DBT rule on what a private force can reasonably be expected to defend against, which excludes air-based

threats, does not ensure adequate protection of the public

health and safety. But, the Commission has an “overall statutory mandate to provide adequate protection to nuclear

plants,” which is not abdicated by its failure to fully protect

against the threat of air-based attacks through an individual

regulatory decision. Riverkeeper, Inc. v. Collins, 359 F.3d

156, 169 (2d Cir. 2004). Here, while the NRC determined that

air-based threats were beyond the scope of the DBT rule, the

Commission provided two primary grounds to support its

determination that adequate protection was met: 1) active protection against airborne threats by other Federal agencies, and

2) the ability of mitigative measures to limit the effects of an

aircraft strike. 72 Fed. Reg. 12,705, 12,711. In its briefing, the

NRC further explained that its judgment was also informed

by: “threat analyses, by experience in the enforcement of

DBT orders, by knowledge about the robustness of nuclear

power plants, by a knowledge that nuclear power plants are

better guarded than any other private critical infrastructure,

7The Commission has issued a final rule to modify the design features

of nuclear facilities to better withstand the impact of an air-based attack.

See supra n. 5. 

PUBLIC CITIZEN v. NRC 9633
and the guard forces subject to more oversight than any other

civilian industry security force, by new studies of how plants

might respond to an air crash, and by a knowledge of actions

that other Federal agencies have taken since 2001 to protect

against air threat.” Brief for Respondents at p. 46 (internal

citations omitted). Though set forth in its briefing, this reasoning is consistent with the reasoning included in the Commission’s final ruling and we accept it as the NRC’s considered

views. See Coke, 127 S. Ct. at 2349. Adequate protection may

be given content through a case-by-case application of the

Commission’s technical judgment, including its knowledge of

actions that other Federal agencies have taken since 2001 and

its active coordination with many of those agencies. See Concerned Scientists II, 880 F.2d 552, 558 (D.C. Cir. 1989).8

[4] It is not implausible for the Commission to determine

that most attacks will be prevented in the first instance by the

coordinated efforts of multiple Federal agencies. It is also not

implausible, based on the evidence before the Commission,

for the NRC to conclude that, in the event that an airplane is

able to strike a facility, the mitigative and protective measures

imposed through the DBT Orders and the revised DBT would

likely prevent any serious harm from occurring. The adequate

protection standard need not prevent “each and every” potential attack, as advocated by amicus State of California,

because the standard “permits the acceptance of some level of

risk” and does not require “absolute protection.” Concerned

Scientists I, 824 F.2d 108, 114, 118 (D.C. Cir. 1987). 

[5] “[T]he NRC’s considered conclusion- right or wrongthat [air-based threats were] being adequately addressed by

8The extremely broad discretion granted to the Commission to ignore

the risks of enemy attacks and sabotage in assessing adequate protection

by the Siegel court, see 400 F.2d at 783-784, however, would not apply

today given the Commission’s own establishment of DBTs under the adequate protection standard and Congress’s direction in 42 U.S.C. § 2210e.

See also Riverkeeper, 359 F.3d at 168 n.14. 

9634 PUBLIC CITIZEN v. NRC
other agencies of government and its consequent decision to

leave the matter to those agencies cannot amount to an ‘abdication’ of its statutory duty under the AEA to insure that the

public health and safety is adequately protected. Relying on

other governmental bodies to address a risk is not equivalent

to ignoring the risk.” Riverkeeper, 359 F.3d at 170;9see also

42 U.S.C. § 2201(f) (authorizing the Commission to utilize

other Federal agencies to perform such functions on its behalf

as may appear desirable). Here the Commission is not merely

relying on other government bodies, but is an active participant in coordinating for protection of nuclear facilities. See 72

Fed. Reg. 12,705, 12,710. The NRC’s reliance on other government agencies, whose charge is to provide security and

defense of the nation against such attacks, is neither inconsistent with its past practices nor an unreasonable interpretation

of its statutory obligations. 

Petitioners’ argument that the NRC’s inclusion of passive

measures to protect against vehicle threats in the 1994 revision necessitates the inclusion of passive measures against airborne threats now, is unavailing. In the 1994 DBT rule, the

Commission explicitly stated that its decision to include passive barriers against vehicle intrusions and explosions was not

based on adequate protection, but as a “matter of prudence”

to provide a “substantial increase in protection.” 59 Fed. Reg.

38,889, 38,891, 896. Thus, it cannot be said here that the

Commission is obligated to find, based on prior decisions,

that passive measures are necessary to provide adequate protection.10 And, as discussed above, the Commission was consis9The Riverkeeper court also noted that the “FAA and Department of

Defense have acted more than once to protect airspace above nuclear

power plants from what were thought to be credible threats against specific sites.” 359 F.3d at 169. 

10It is also reasonable for the Commission to treat the interagency

response to air-based threats differently than in land vehicle or waterbased vehicle attacks. There are far fewer airplanes than either trucks or

boats, and they are far more regulated. Airspace is monitored by federal

agencies in a manner which cannot be duplicated on all of the nation’s

roadways and waterways. 

PUBLIC CITIZEN v. NRC 9635
tent in including within the scope of the DBT rule only those

threats a private force can reasonably be expected to defend

against. The NRC’s determination that private forces can reasonably defend against vehicle and water-based attacks does

not require the Commission to come to the same conclusion

regarding airborne threats. Once the Commission determined

that adequate protection was met, it was under no obligation

to further consider the beamhenge concept outlined in the

CBG petition.

[6] Petitioners also argue that the Commission improperly

considered cost in its assessment. This allegation has no basis

in the record. The Commission has consistently stated that its

determination of adequate protection was not based on cost.

72 Fed. Reg. 12,705, 12,714. The NRC has provided sufficient explanation of the reasonableness standard to show that

it is animated by considerations of practicality, feasability,

and the proper division of defense between government agencies rather than cost concerns. For example, Petitioners argue

that any reasonableness limitation on the size of a private

security force must be driven by cost. This argument ignores

potential basic feasability concerns that may arise with maintaining facilities for a private “standing army.” The Commission’s decision to limit the size of private security forces is

neither arbitrary nor an abuse of the Commissioner’s discretion. Moreover, because the Commission found that the adequate protection standard was satisfied through mitigation

measures and active defense by other federal agencies, any

decision to include air-based threats in the DBT could have

properly considered costs. When the NRC uses its permissive

authority to extend public safety measures beyond those

required by “adequate protection,” it may legitimately include

costs in its assessment. See Concerned Scientists I, 824 F.2d

at 118.

C. Compliance with Congress’s Directives in 42 U.S.C.

§ 2210e 

[7] Petitioners also contend that the Commission’s final

rule is contrary to law because the Commission failed to com9636 PUBLIC CITIZEN v. NRC
ply with Congress’s directive to “consider” “the potential for

water-based and air-based threats.” § 2210e(b)(6). This argument is without merit. The Commission thoroughly discussed

its assessment of air-based threats in the final rule. The Commission also implemented many mitigative measures to limit

the effects of an air-strike and coordinated with other agencies

to prevent an airborne attack. The direction to “consider” nonexclusive factors does not necessitate including that factor in

the final rule, as Petitioners admit. The NRC’s interpretation

of the directive from Congress is reasonable. The statute has

no legislative history that could counter the Commission’s

interpretation, nor can it be assumed, given the “virtually

unique” authority of the NRC to achieve its statutory objectives, see Seigel, 400 F.2d at 783, that Congress intended to

interfere with the Commission’s authority any more than is

facially clear from the statute. 

[8] Petitioner’s argument that air-based threats must necessarily be within the scope of the DBT rule simply because

they were included as a § 2210e factor is also flawed. The

Commission does not argue that it could not have legally chosen to include air-based threats within the scope of the DBT.

Section 2210e allowed the Commission the flexibility to

determine whether or not to include each individual factor in

the final rule. There is no indication that the Commission

could not exercise that discretion in determining a factor was

beyond the scope of the DBT rule, rather than excluding the

factor on any other discretionary basis.11 Petitioners cite no

authority to so limit the Commission’s discretion where a factor is not mandated by Congress and we decline to imply any

such limitation. Compare Public Citizen v. FMCSA, 374 F.3d

1209, 1216 (D.C. Cir. 2004) (finding agency rule arbitrary

11Moreover, the first factor listed in § 2210e is “the events of September

11, 2001.” This illustrates that Congress could not have reasonably

expected the NRC to treat the factors as a sort of shopping list of threats

to include wholesale in the final rule, without further agency analysis and

expertise. 

PUBLIC CITIZEN v. NRC 9637
and capricious where the “agency neglected to consider a statutorily mandated factor” under its organic statute).

D. Reliance on Non-Public Information 

Petitioners next argue that the Commission improperly

relied on non-public information when engaging in the DBT

rulemaking. The cases relied upon by Petitioners, however,

involve cases where an agency relies on general factual information not provided to the public, and do not govern this

case. See, e.g., Kern County Farm Bur. v. Allen, 450 F.3d

1072, 1076 (9th Cir. 2006). Here, the AEA specifically allows

the Commission to maintain “safeguards information” that is

not available to the public. 42 U.S.C. §§ 2167, 2201(i); see

also 10 C.F.R. § 73.21. The APA also exempts from the general rule information it is specifically authorized to withhold

from public scrutiny. See 5 U.S.C. § 552(b)(3). The Commission cannot be required to reveal classified information about

nuclear facilities, nor would it be able to do so while fulfilling

its duty to maintain the common defense and security of classified information. See also Siegel, 400 F.2d at 786 (“When,

as here, a statute does not require that a particular kind of rule

making be on a record made after a public hearing, the Commission is not confined to evidence presented in some formal

manner. It may act not only on the basis of the comments

received in response to its notice of rule making, but also

upon the basis of information available in its own files, and

upon the knowledge and expertise of the agency.”) (citing

Pacific Coast European Conference v. United States, 350

F.2d 197, 205 (9th Cir. 1965)). 

[9] We hold the Commission acted neither arbitrarily or

capriciously in excluding the threat of air-based attacks from

the scope of the DBT rule, nor contrary to law in finding that

adequate protection was satisfied without incorporating passive protective measures against air-based attacks in the DBT

rule. 

9638 PUBLIC CITIZEN v. NRC
E. NEPA Analysis 

Petitioners also challenge the sufficiency of the EA provided by the Commission, arguing that the NRC should have

analyzed its decision to exclude air-based threats from the

DBT rule and included that environmental analysis in the

alternative action portion of the EA. They argue that the decision to exclude air-based threats is an agency action that “increases the risk of a successful terrorist attack,” and that that

decision produces its own adverse environmental affects. Petitioners rely on this court’s decisions in Center for Biological

Diversity v. NHTSA, 538 F.3d 1172, 1216 (9th Cir. 2008), and

San Luis Obispo Mothers for Peace v. NRC (Mothers for

Peace), 449 F.3d 1016 (9th Cir. 2006). 

[10] “An EA shall include brief discussions of the need for

the proposal and the environmental impacts of the proposed

action and alternatives.” Center for Biological Diversity, 538

F.3d at 1215 (quoting 40 C.F.R. § 1508.9(b)) (internal citations and alterations omitted). Because the Commission acted

within its discretion in concluding that air-based threats were

beyond the scope of the DBT rule, however, it was unnecessary for the Commission to consider that decision as an alternative course within the scope of the rule. The Commission’s

determination that air-based threats were outside the scope of

the DBT rule distinguishes this case from a case like Center

for Biological Diversity, where we held an agency must consider a broad range of alternative actions within the scope of

the rule at issue, beyond those alternatives the agency seriously considered. We decline to extend that holding to create

a rule that ignores reasonable boundaries in the scope of an

EA alternative action analysis. The Commission did not

merely select among a range of options, but instead determined air-based threats were not properly addressed by the

DBT rule. As noted above, this decision was within the Commission’s discretion and it need not include an analysis of airbased threats within the EA alternative action section. 

PUBLIC CITIZEN v. NRC 9639
[11] By only highlighting one potential deficiency in the

EA that could impact the environment, petitioners implicitly

agree with the Commission’s argument that the rule was otherwise only beneficial to the environment, because it reduced

the threat of a terrorist attack. Therefore, we do not address

whether the NRC violated this court’s holding in Mothers for

Peace, or whether the effects of an air-based attack (rather

than the possibility of a terrorist attack) were too speculative

to necessitate their inclusion in the EA. See Mothers for

Peace, 449 F.3d at 1033-1034. Because Petitioners have identified no effect of the revised DBT rule that “may cause significant degradation of some human environmental factor,” no

EIS was necessary. Center for Biological Diversity, 538 F.3d

at 1219 (quoting Idaho Sporting Cong. v. Thomas, 137 F.3d

1146, 1149 (9th Cir. 1998)); see also Douglas County v. Babbitt, 48 F.3d 1495, 1505 (9th Cir. 1995) (“[A]n EA or an EIS

is not necessary for federal actions that conserve the environment.”). 

PETITION DENIED. 

THOMAS, Circuit Judge, concurring in part and dissenting in

part:

I join the majority in holding that the Nuclear Regulatory

Commission’s (“NRC”) use of a “reasonable expectation”

standard as a proxy for the division of responsibility between

public and private forces is not arbitrary and capricious, that

the NRC did not improperly withhold safeguarded information, and that the NRC did not violate the National Environmental Policy Act. However, I would grant the petition for

review as to whether the NRC acted arbitrarily and capriciously in excluding air-based threats from the Design Basis

Threat (“DBT”) rule.

No one disputes that there is a credible threat of terrorists

using commercial aircraft to attack nuclear power plants.

9640 PUBLIC CITIZEN v. NRC
Nevertheless, the NRC concludes it was not necessary to

include air-based threats in its DBT rule because: (1) other

federal agencies will largely prevent such attacks in the first

instance, and (2) the effects of any successful attack will be

minimal, or at least minimized.

The NRC claims it conducted “detailed, site-specific engineering studies” that “confirm the low likelihood of [an airplane attack] both damaging the reactor core and releasing

radioactivity that could affect public health and safety.”

Unfortunately, this comforting conclusion directly contradicts

the unanimous findings of the studies available in the administrative record—some commissioned by the NRC itself—that

some of our nuclear facilities may not be able to withstand the

impact of a commercial jet airplane. 

One study found that an aircraft strike could cause radioactive leakage along with “[e]xtensive destruction of [the] reactor building.”

1

 One cautioned that a core meltdown could

result from even a light aircraft striking a nuclear plant’s control building,2

 and another similarly concluded that even a

small plane could damage a plant’s reactor core.3 Still

another, performed by the Argonne National Laboratory,

warned that an airplane strike causing rapid depressurization

of the plant’s secondary cooling system might very well cause

“serious damage if not total meltdown.”

4

 Even the NRC itself

1GERMAN REACTOR SAFETY ORG., PROTECTION OF GERMAN NUCLEAR

POWER PLANTS AGAINST THE BACKGROUND OF THE TERRORIST

ATTACKS IN THE U.S. on SEPT. 11, 2001, at 7-9 (Greenpeace Germany

trans.) (2002), available at http://www.greenpeace.org/raw/content/

international/press/reports/protection-of-german-nuclear-p-2.pdf. 

2POWER AUTH. OF THE STATE OF NEW YORK & CONSOL. EDISON CO.,

INDIAN POINT PROBABILISTIC SAFETY STUDY 7.6-3 (1982). 

3

Ian B. Wall, Probabilistic Assessment of Aircraft Risk for Nuclear

Power Plants, 15 NUCLEAR SAFETY 276 (1974). 

4C.A. KOT, ET AL., ARGONNE NATIONAL LABORATORY EVALUATION OF

AIRCRAFT CRASH HAZARDS ANALYSES FOR NUCLEAR POWER PLANTS 51-52

(1982). 

PUBLIC CITIZEN v. NRC 9641
has recently determined that an airplane strike has a substantial chance of causing “catastrophic” damage to spent nuclear

fuel pools.5 The studies referenced in the DBT rule, which apparently6

“confirm” the low likelihood of radioactive release, are

the sole exceptions.

Of course, we must defer to an agency’s expertise in

weighing evidence. However, there is no sign in this record

that the agency conducted that exercise here. Not only did the

NRC fail to rebut the multitude of studies that conflicted with

its own assessment, but it failed to even mention the contrary

studies. This failure alone is grounds to grant the petition. See

Motor Vehicle Mfrs. Ass’n v. State Farm Mut. Auto. Ins. Co.,

463 U.S. 29, 43 (1983) (noting that an agency’s failure to

offer an explanation for its decision that runs counter to the

evidence before it is arbitrary and capricious); Islander E.

Pipeline Co. v. State of Connecticut, 467 F.3d 295, 313 (2d

Cir. 2006) (observing that an agency’s failure to mention contrary scientific studies renders its conclusions arbitrary and

capricious). 

Moreover, the NRC’s determination that nuclear plants can

successfully withstand airplane strikes contradicts the agency’s own analysis. In its previous DBT rule, the NRC found

that truck bombs can inflict severe damage on nuclear power

plants. See Nuclear Regulatory Commission, Protection

Against Malevolent Use of Vehicles at Nuclear Power Plants,

59 Fed. Reg. 38889, 38891 (August 1, 1994) (stating that such

bombs’ “contribution to [nuclear] core damage frequency

could be high”). The NRC provides no explanation as to why

5NUCLEAR REGULATORY COMMISSION, TECHNICAL STUDY OF SPENT FUEL

POOL ACCIDENT RISK AT DECOMISSIONING NUCLEAR POWER PLANTS at 3-23

(2001); see also NAT’L ACAD. OF SCICIENTISTS, SAFETY AND SECURITY OF

COMMERCIAL SPENT NUCLEAR FUEL STORAGE (2006). 

6We must accept on faith that the NRC’s studies actually stand for the

proposition for which they are cited, as the agency has not offered them

for our in camera review, even in redacted form. 

9642 PUBLIC CITIZEN v. NRC
we should fear the effects of a truck bomb attack, but not

those of a commercial airliner strike. Nor does the NRC

explain why the construction of passive structural barriers is

a critical component of defense against truck bomb attacks,

while it is completely unnecessary for the NRC even to consider the installation of passive barrier defenses (such as

beamhenges) to attacks by air. The distinction the agency

draws between the risk of truck bombs and hijacked airliner

attacks is inconsistent with our nation’s recent tragic experiences and common sense. 

Although we owe the NRC considerable deference, the

NRC owes the public a rational and reasonable explanation

why it would exclude from its rule consideration of terrorist

air attacks on nuclear facilities. In the face of near-uniform

scientific studies warning of serious risk, bare assurances by

the NRC that we are safe do not satisfy this minimal agency

burden.

PUBLIC CITIZEN v. NRC 9643