Petitioner Joseph J. Macktal requests review of a final order of the Secretary of Labor, pursuant to Section 210(c)(1) of the Energy Reorganization Act (“ERA”). 42 U.S.C. § 5851(c)(1) (1978). More particularly, he seeks reversal of a Final Decision and Order of the Administrative Review Board (“ARB”), dismissing his claim against Intervenor-Respondent Brown & Root, Inc. (“Brown & Root”) under the whistle blowеr protection provision of the ERA. ERA § 210(a), codified at 42 U.S.C. § 5851(a) (1978) (“Section 210”). For reasons that follow, we deny Macktal’s petition for review and affirm the ARB’s Final Decision and Order.
I.
Brown & Root was the general contractor in the construction of the Comanche Peak Steam Electric Station (“CPSES”), a nuclear power plant assembled during the 1980s near Fort Worth, Texas. Brown & Root hired Macktal in January 1985 as a journeyman electrician at CPSES. He was promoted to electrical foreman in May 1985.
As foreman, Macktal supervised a crew of employees inspecting electrical conduits to ensure that they had been properly installed. In this role, he devеloped a number of safety concerns, which he reported to his immediate supervisor. He was subsequently given a counseling report and demoted to journeyman electrician in September 1985. He was reassigned to the night shift, where he was issued a safety violation for failing to wear proper eye protection when operating a band saw. A few days later, he was reassigned once more to the day shift. Mack-tal testified that he was subsequently asked to perform various activities in violation of safety procedures. He made safety-related complaints to his supervisor, the general foreman, and SAFETEAM, an independent safety group established by and operated under the direction of the CPSES “site owner,” Texas Utilities Electric Co. He alleges that he was then subjected to numerous forms of harassment, including citation for an unwarranted safety violation, loss of his tools, a delayed paycheck, failure to receive a personal phone call, and refusаl of management to grant a request for leave without pay. Macktal reported this alleged harassment to SAFETEAM.
On January 2,1986, Macktal was given a counseling report for excessive absenteeism. He responded the next day with a handwritten memorandum in which he objected to the counseling report and stated that his “plan of action” was to file a noncompliance complaint with the Nuclear Regulatory Commission (“NRC”) concerning the safe operation of CPSES. He also *326 stated in the memorandum: “In a[n] effort to preserve my health and avoid any further harassment, I wish to be relieved of my duties until the TEC, NLRB, NRC can resolve these matters.” A few hours after Macktаl submitted this memorandum, his employment with Brown & Root was terminated. Macktal did not object to this action, and testified that he understood he was being terminated. At the time of his termination, Macktal had not yet contacted any government agency concerning any safety violations, and did not do so until several months later.
In February 1986, Macktal filed a claim against Brown
&
Root with the Secrеtary of Labor under Section 210, alleging that he had been constructively discharged. The Wage and Hour Division of the Department of Labor notified Macktal in March 1986 that his claim lacked merit. Macktal requested a hearing, before an administrative law judge (“ALJ”). The ALJ encouraged the parties to settle, and the parties signed a sеttlement agreement in January 1987. Macktal later sought to have the settlement set aside. In November 1989, the Secretary issued an order rejecting one paragraph of the settlement as contrary to public policy, but otherwise approving the settlement. This court reversed the Secietary’s order in
Macktal v. Secretary of Labor,
The ALJ finally held a hearing on the merits in February 1996, more than a decade after the original claim was filed. Pri- or tо the hearing, Brown & Root twice moved for summary judgment. At the hearing, the ALJ ruled that internal whistle blowing was not protected under Section 210 and the prior rulings of this court, and that the ALJ therefore would not consider Macktal’s internal complaints as support for his claim. In November 1996, the ALJ issued a Recommended Decision and Order granting Brown & Root’s mоtion for summary judgment. Macktal filed exceptions to the ALJ’s Recommended Decision and Order. In January 1998, after further briefing, the ARB issued a Final Decision and Order dismissing Macktal’s complaint, finding that Macktal had not engaged in any protected activity under the ERA. This timely petition followed.
II.
Review of the ARB’s Final Decision and Order is governed by the standard of review set forth in the Administrative Procedure Act, 5 U.S.C. § 706(2). This court must affirm the Secretary’s decision unless it is arbitrary, capricious, an abuse of discretion, or otherwise contrary to law, or unless the decision is not supported by substantial evidence. 5 U.S.C. § 706(2)(A). Agency interpretations of circuit law, however, are reviewed
de novo. See Harris v. Railroad Retirement Board,
III.
Macktal argues that the ARB erred in finding that he had not engaged in any protected activity under Section 210 prior to his termination by Brown & Root. He contends that the ARB misinterpreted circuit precedent to foreclose recovery. We disagree. Though our reasoning differs somewhat from that of the ARB, we nonetheless conclude that the ARB acted cоrrectly in dismissing Macktal’s complaint.
Prior to the 1992 Amendments to the ERA, Section 210 provided as follows:
No employer ... may discharge any employee or otherwise discriminate against any employee with respect to his compensation, terms, conditions, or privileges of employment because the employee (or any person acting pursuant to a request of the employee)—
(1) commenced, caused to be commenced, or is about to commence or *327 cause to be commenced a proceeding under this chapter or the Atomic Energy Act of 1954, as amended, or a proceeding for the administration or enforcement of any requirement imposed under this chapter or the Atomic Energy Act of 1954, аs amended;
42 U.S.C. § 5851(a) (1978) (emphasis added). 1
The complainant has the initial burden of establishing a
prima facie
case of discrimination under this provision. To meet this burden, the complainant must show: (1) that he engaged in protected activity; (2) that the employer was aware of the protected activity; (3) that the employer took some adverse action against him; and (4) that the evidence is sufficient to permit an inferenсe that the protected activity was the likely reason for the adverse action.
See Couty v. Dole,
The principal question before us is whether the ARB erred in determining that Macktal failed to show that he was engaged in protected activity at the time of the alleged adverse actions.
2
The ARB’s determination that Macktal was not engagеd in protected activity under Section 210 is based on this court’s opinion in
Brown & Root, Inc. v. Donovan,
Macktal seeks to distinguish his case from Brown & Root on two grounds. First, he notes that Atchison’s nonconfor-mance reports were all routine internal reports filed pursuant to Atchison’s job-related responsibilities, whereas Macktal “went beyond his chain-of-command and contacted SAFETEAM, a semi-independent and NRC-endorsed program specifically designed to review whistleblower allegations.” Macktal points out that SAFETEAM’s own internal operating procedures both mandated that SAFE-TEAM report certain violations on its own to the NRC and recognized that contacts with SAFETEAM were a “forewarning of a later allegation to the NRC *328 or another regulatory body.” Second, Macktal notes that Atchison never gave any indication that he was about to contact the NRC or any other official government agency, whereas Macktal delivered a handwritten memorandum to his superiors at Brown & Root just hours before his termination advising management that he was going to contact the NRC. Macktal argues that these extra actions on his рart, absent in Brown & Root, bring his conduct within the sphere of protected activity under the “about to” language of Section 210. He notes that the Brown & Root panel expressly omitted the phrase “about to” when it quoted the “relevant language” of Section 210. See id. at 1031. Thus, he argues, the panel’s reasoning'does not extend to that portion of the statute. Wе find these distinctions unavailing.
A.
With respect to Macktal’s complaints to SAFETEAM, we are governed by this court’s opinion in
Ebasco Constructors, Inc. v. Martin,
Ebasco
is clearly controlling in the present case. This court adheres strictly to the maxim that one panel of the court cannot overturn another, even if it disagrees with the prior panel’s holding.
See Texas Refrigeration Supply v. FDIC,
B.
Macktаl’s memorandum expressing his intention to file a complaint with the NRC presents a more difficult issue. As Macktal observes, the Brown & Root court did not consider the “about to” pro *329 vision of Section 210, because that provision was irrelevant under the facts of Brown & Root. Contrary to the ARB’s findings, this strongly suggests that the issue of whether Macktal’s memorandum was protected activity under Section 210 is not directly governed by Brown & Root or Ebasco. Thе Secretary notes that this very same argument was unsuccessfully argued before this court in Ebasco, and that although the court did not specifically address the argument, it nonetheless concluded that Brown & Root was controlling. A prior panel’s silence on a particular issue, however, is not binding on this panel. It therefore falls to us to determine whether а written expression of intent to file a complaint with the NRC constitutes protected activity under Section 210. We conclude that it does.
We need go no further than the plain language of Section 210 to conclude that a written expression of intent to file a complaint with the NRC is protected activity under the ERA. Section 210 protects from retaliatory action any employee who “commenced,” “caused to be commenced,” or “is about to commence or cause to be commenced” a proceeding under the ERA or the Atomic Energy Act. 42 U.S.C. § 5851(a)(1) (1978). When the
Brown & Root
panel concluded that “employee conduct which does not involve the employee’s contact or involvement with a competent organ of government is not protected” under Section 210,
As noted abоve, however, evidence that the complainant engaged in protected activity is only the first of four prima facie requirements under Section 210. Macktal must also show that the evidence is sufficient to permit an inference that the protected activity was the likely reason for the adverse action. It is at this point that his claim collapses. In addition to expressing his intention to file a complaint with the NRC, Macktal also stated in his memorandum: “In a[n] effort to preserve my health and avoid any further harassment, I wish to be relieved of my duties until the TEC, NLRB, NRC can resolve these matters.” The ARB observed that “[i]t would have required considerable mental gymnastics on the part of Brown & Root managers to recognize that, when Macktal said he wanted to be relieved of his duties, he really meant he wanted to be reassigned to work that did not require him to violate NRC procedures.” Macktal v. Brown & Root, Inc., 86-ERA-23, slip op. at 5 (Sec’y Dec. Jan. 6, 1998). Thus, the ARB concluded, “[w]e agree with the ALJ that a reasonable person could only interpret Macktal’s request as a resignation and could not be held responsible for failure to intuit what Macktal now claims was on his mind.” Id., slip op. at 5-6. The ARB’s conclusion is clearly supported by substantial evidence, and we do not find it to be arbitrary, capricious, an abuse of discretion, or otherwise contrary to law. Thus, the Final Decision and Order of the ARB must be affirmed.
IV.
Fоr the foregoing reasons, Macktal’s petition for review is DENIED and the Final *330 Decision and Order of the ARB is AFFIRMED. 5
Notes
. In 1992, Congress amended the ERA to include explicit protection for internal complaints. The act as amended protects an employee who "notified his employer of an alleged violation of this chapter or the Atomic Energy Act of 1954,” 42 U.S.C. § 5851(a)(1)(A), and аn employee who "refused to engage in any practice made unlawful by this chapter or the Atomic Energy Act of 1954, if the employee has identified the alleged illegality to the employer,” 42 U.S.C. § 5851(a)(1)(B). These amendments do not apply here, because the present claim was filed well before the October 24, 1992 date of еnactment.
. Brown & Root argues that, irrespective of the merits, Macktal’s claim has been extinguished by his refusal to return settlement funds he received from Brown & Root. That issue was addressed in an earlier order by the Secretary of Labor, dated July 11, 1995, which Brown & Root did not appeal. Regardless, it was not raised in the Final Decision and Order at issuе here, and therefore falls outside of this court's jurisdiction under 42 U.S.C. § 5851(c)(1).
. Unpublished opinions issued before January 1, 1996 are binding precedent in this circuit. See 5th Circuit Rule 47.5.3.
. Macktal urges us in the alternative to take this matter en banc on the court's own motion and to overrule Brown & Root. We decline to do so. Macktal may, of course, file a formal suggestion for rehearing en banc at the appropriate time. See Fed.' R.App. P. 35.
. Brown & Root argues that it is entitled to an award of sanctions under 28 U.S.C. §§ 1912 and 1927 and Fed. R.App. P. 38. We do not find that Macktal's appeal was frivolous or meritless. Therefore, Brown & Root’s request for sanctions is denied.