| Operating Segments | 12. Operating Segments   In accordance with ASC 280, “Segment
Reporting”, the Company defines an operating segment as a business activity: (1) from which we may earn revenue and incur
expenses; (2) whose operating results are regularly reviewed by the chief operating decision maker (“CODM”) to make
decisions about resources to be allocated to the segment and assess its performance; and (3) for which discrete financial information
is available.   Our reporting segments are defined as
below:   TREATMENT SEGMENT, which includes:   
    |  | - | nuclear, low-level radioactive, mixed waste (containing both hazardous and low-level radioactive constituents), hazardous and non-hazardous waste treatment, processing and disposal services primarily through three uniquely licensed and permitted treatment and storage facilities; and |  
    |  | - | R&D activities to identify, develop and implement innovative waste processing techniques for problematic waste streams. |    SERVICES SEGMENT, which includes:   
    |  | - | Technical services, which include: |  
    |  |  |  |    
    |  | ○ | professional radiological measurement and site survey of large government and commercial installations using advanced methods, technology and engineering; |  
    |  | ○ | integrated Occupational Safety and Health services including IH assessments; hazardous materials surveys, e.g., exposure monitoring; lead and asbestos management/abatement oversight; indoor air quality evaluations; health risk and exposure assessments; health & safety plan/program development, compliance auditing and training services; and OSHA citation assistance; |  
    |  | ○ | global technical services providing consulting, engineering, project management, waste management, environmental, and decontamination and decommissioning field, technical, and management personnel and services to commercial and government customers; and |  
    |  | ○ | on-site waste management services to commercial and governmental customers. |  
    |  |  |  |    
    |  | - | Nuclear services, which include: |  
    |  |  |  |    
    |  | ○ | technology-based services including engineering, decontamination and decommissioning (“D&D”), specialty services and construction, logistics, transportation, processing and disposal; |  
    |  | ○ | remediation of nuclear licensed and federal facilities and the remediation cleanup of nuclear legacy sites. Such services capability includes: project investigation; radiological engineering; partial and total plant D&D; facility decontamination, dismantling, demolition, and planning; site restoration; logistics; transportation; and emergency response; and |  
    |  |  |  |    
    |  | - | A company owned equipment calibration and maintenance laboratory that services, maintains, calibrates, and sources (i.e., rental) health physics, IH and customized NIOSH instrumentation. |  
    |  | - | A company owned gamma spectroscopy laboratory for the analysis of oil and gas industry solids and liquids. |    MEDICAL SEGMENT, which includes: Research
and Development (“R&D”) of the Company’s medical isotope production technology by our majority-owned Polish
subsidiary, Perma-Fix Medical S.A. and its wholly-owned subsidiary Perma-Fix Medical Corporation (“PFM Corporation”)
(together known as “PF Medical” or the Medical Segment). The Company’s Medical Segment has not generated any
revenue as it remains in the R&D stage. The Medical Segment has substantially reduced its R&D activities due to the need
for capital to fund these activities. The Company anticipates that the Medical Segment will not resume full R&D activities
until the necessary capital is obtained through its own credit facility or additional equity raise or obtains partners willing
to provide funding for its R&D. All costs incurred by the Medical Segment are reflected within R&D in the accompanying
consolidated financial statements.   Our reporting segments exclude our corporate
headquarters and our discontinued operations (see “Note 11 – Discontinued Operations”) which do not generate
revenues.   The table below presents certain financial
information of our operating segments for the three months ended March 31, 2019 and 2018 (in thousands):   Segment Reporting for the Quarter Ended March 31, 2019   
    |  |  | Treatment |  |  | Services |  |  | Medical |  |  | Segments Total |  |  | Corporate(1) |  |  | Consolidated Total |  |  
    | Revenue from external customers |  | $ | 9,905 |  |  | $ | 1,803 |  |  |  | — |  |  | $ | 11,708 |  |  | $ | — |  |  | $ | 11,708 |  |  
    | Intercompany revenues |  |  | 2 |  |  |  | 21 |  |  |  | — |  |  |  | 23 |  |  |  | — |  |  |  | — |  |  
    | (Negative) gross profit |  |  | 2,957 |  |  |  | (456 | ) |  |  | — |  |  |  | 2,501 |  |  |  | — |  |  |  | 2,501 |  |  
    | Research and development |  |  | 147 |  |  |  | — |  |  |  | 74 |  |  |  | 221 |  |  |  | 6 |  |  |  | 227 |  |  
    | Interest income |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 81 |  |  |  | 81 |  |  
    | Interest expense |  |  | (17 | ) |  |  | (9 | ) |  |  | — |  |  |  | (26 | ) |  |  | (61 | ) |  |  | (87 | ) |  
    | Interest expense-financing fees |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (10 | ) |  |  | (10 | ) |  
    | Depreciation and amortization |  |  | 237 |  |  |  | 78 |  |  |  | — |  |  |  | 315 |  |  |  | 8 |  |  |  | 323 |  |  
    | Segment income (loss) before income taxes |  |  | 1,875 |  |  |  | (1,012 | ) |  |  | (74 | ) |  |  | 789 |  |  |  | (1,300 | ) |  |  | (511 | ) |  
    | Income tax expense |  |  | (39 | ) |  |  | — |  |  |  | — |  |  |  | (39 | ) |  |  | — |  |  |  | (39 | ) |  
    | Segment income (loss) |  |  | 1,836 |  |  |  | (1,012 | ) |  |  | (74 | ) |  |  | 750 |  |  |  | (1,300 | ) |  |  | (550 | ) |  
    | Expenditures for segment assets |  |  | 222 |  |  |  | 2 |  |  |  | — |  |  |  | 224 |  |  |  | — |  |  |  | 224 |  |    Segment Reporting for the Quarter Ended March 31, 2018   
    |  |  | Treatment |  |  | Services |  |  | Medical |  |  | Segments Total |  |  | Corporate(1) |  |  | Consolidated Total |  |  
    | Revenue from external customers |  | $ | 8,959 |  |  | $ | 3,699 |  |  |  | — |  |  | $ | 12,658 |  |  | $ | — |  |  | $ | 12,658 |  |  
    | Intercompany revenues |  |  | 213 |  |  |  | 14 |  |  |  | — |  |  |  | 227 |  |  |  | — |  |  |  | — |  |  
    | Gross profit |  |  | 2,780 |  |  |  | 541 |  |  |  | — |  |  |  | 3,321 |  |  |  | — |  |  |  | 3,321 |  |  
    | Research and development |  |  | 114 |  |  |  | — |  |  |  | 100 |  |  |  | 214 |  |  |  | 18 |  |  |  | 232 |  |  
    | Interest income |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 49 |  |  |  | 49 |  |  
    | Interest expense |  |  | — |  |  |  | (1 | ) |  |  | — |  |  |  | (1 | ) |  |  | (52 | ) |  |  | (53 | ) |  
    | Interest expense-financing fees |  |  | — |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (9 | ) |  |  | (9 | ) |  
    | Depreciation and amortization |  |  | 240 |  |  |  | 123 |  |  |  | — |  |  |  | 363 |  |  |  | 9 |  |  |  | 372 |  |  
    | Segment income (loss) before income taxes |  |  | 1,744 |  |  |  | (86 | ) |  |  | (100 | ) |  |  | 1,558 |  |  |  | (1,254 | ) |  |  | 304 |  |  
    | Income tax expense |  |  | (51 | ) |  |  | — |  |  |  | — |  |  |  | (51 | ) |  |  | — |  |  |  | (51 | ) |  
    | Segment income (loss) |  |  | 1,693 |  |  |  | (86 | ) |  |  | (100 | ) |  |  | 1,507 |  |  |  | (1,254 | ) |  |  | 253 |  |  
    | Expenditures for segment assets |  |  | 220 |  |  |  | 25 |  |  |  | — |  |  |  | 245 |  |  |  | 3 |  |  |  | 248 |  |    (1) Amounts reflect
the activity for corporate headquarters not included in the segment information. |