Accounts Payable Manager

Radiant is an El Segundo, CA-based company building the world's only mass-produced, transportable nuclear microreactors. The U.S. grid is under growing strain, with power demand accelerating, driving higher utility costs, rising carbon emissions, and interconnection backlogs. Radiant has a solution, transportable, on-site power. Our first reactor, Kaleidos, is 1 megawatt: small enough to be factory-built, transported by land, sea, or air, and deployed wherever power is needed.

1 MW can power 1000 homes for five years. Ship it back and we refuel for a 20 year operating life. We made energy a product that can be used for critical infrastructure like military bases, data centers, hospitals, and remote sites, as well as the commercial main street businesses that keep America running. Founded in 2020, Radiant is under contract to deliver power to the U.S. Army, Navy and Air Force and has signed pre-order agreements with Equinix, with deployments beginning in 2028.

Radiant is seeking an AP Manage
r to own our end-to-end accounts payable operations. We process 800-1,300 invoices monthly across fragmented systems (Quick Books, ION, and Ramp) with no automatic integration or three-way match. This role will manage the full invoice-to-payment cycle, build scalable AP infrastructure, and establish the controls and processes needed to support our growth from prototype development through production ramp.

This is a hands-on role with significant ownership. You'll process high volumes while simultaneously building the systems, controls, and documentation that will scale with the company. You'll partner closely with Supply Chain on procurement workflows and with Finance leadership on cash management strategy and ERP implementation planning.

Responsibilities & Duties:

Invoice Processing & Management

• Process 800-1,300+ invoices monthly across Quick Books, ION, and Ramp

• Review, code, and approve invoices ensuring proper GL account assignment, project codes, and class accounting

• Perform manual three-way matching across disconnected systems until ERP implementation

• Handle employee and candidate reimbursements, corporate card reconciliations, and ad-hoc payment requests

• Manage vendor setup, W-9 collection, and vendor master data maintenance

Payment Processing & Vendor Management

• Execute payment runs to capture early payment discounts and avoid late penalties

• Serve as primary point of contact for 150+ active vendors; resolve inquiries, disputes, and statement reconciliations

• Coordinate with Procurement on vendor onboarding, contracts, and payment terms

• Monitor aging reports and resolve payment holds or exceptions

Process & Controls

• Build scalable AP infrastructure with automations where possible

• Design and document AP policies, procedures, and workflows for a scaling organization

• Implement approval matrices, segregation of duties, and fraud prevention controls

• Build audit-ready documentation and support external audits

System Optimization & ERP Readiness

• Maximize functionality of existing tools:
  Ramp Pro automation, ION workflows, Quick Books coding rules

• Document current-state processes and pain points to inform 2026 ERP requirements

• Lead AP workstream for ERP selection, implementation, and data migration

Compliance & Cross-Functional Partnership

• Maintain 1099 vendor tracking and support sales/use tax compliance and annual filings

• Partner with Supply Chain and Receiving on purchase order workflows and vendor management

• Train employees on policies, Ramp usage, and invoice submission requirements

Required

Qualifications & Skills:

• 5+ years of accounts payable experience, with at least 2 years in a senior or lead AP role

• Experience processing high-volume AP (500+ invoices/month) in a fast-paced environment

• Proficiency with AP automation tools and ERP systems

• Strong understanding of three-way match processes, GL coding, and month-end close procedures

• Experience with 1099 reporting, sales/use tax compliance, and audit support

• Track record of building or improving AP processes and controls

• Excellent attention to detail and ability to manage competing priorities

• Strong communication skills for vendor management and cross-functional collaboration

Desired

Qualifications & Skills:

• Hardware, manufacturing, or aerospace/defense industry background

• Experience with government contract accounting (FAR/DFARS)

• Familiarity with Ramp, Quick Books, and/or ION

• Experience supporting ERP implementations or system migrations

• SQL or reporting tool proficiency for building AP…