Nuclear Outage Equipment Hatches (OEH)


Mechanical Research & Design, Inc., through our MRD Nuclear brand, are the designers and fabricators of temporary to permanent Nuclear Outage Equipment Hatches (OEH) as well as other radioactive sealing containment/isolation barriers, doors, and hatches. An outage equipment hatch is typically a temporary pressure barrier installed as radioactive containment in a reactor access passage during site outages. Our hatches provide simple, rapid-deployment installation and pressure isolation for access entrances in reactor containment or missile walls that are normally open when supporting outage activities. Our engineers, fabricators, and technicians work with our customers to provide the optimal hatch designs, functions, process penetrations, accessories, and more, interfacing fully with the existing site.


During outages at nuclear facilities, primary, long-term equipment hatches are typically removed to facilitate easy access to the reactor and supporting process systems for operations such as refueling and general maintenance. These isolation barriers are typically bulky and time-consuming to remove or re-install should the need for full containment (re-installation) arise suddenly during outage (reactors are usually powered down and idled during outages, however, can still reach critical boiling temperatures rapidly if issues arise, causing the release of radioactive steam and other contaminants). Outage equipment hatches, lighter weight and quicker to install than permanent equipment hatches, are designed to work with existing infrastructure and often include large drive-through sealing doors that can be rapidly closed and locked down should the need arise.


We have several standard as well as custom design configurations, including: semi-permanent (can be removed with hand tools if needed) enclosures that fit between permanent hatches and missile doors, temporary barriers that can be installed by fork-lift during the outage if needed, customized drive through doors to aid in re-fueling and large pump replacement during outages, and other more permanent barriers that remain installed between outages. In some cases, when allowable, we can integrate our hatches directly to access tubes using methods such as welding, and in others, we can provide integral locking dogs or other interfacing restraining devices that we use on everyday pressure isolation tools. Mechanical Research & Design, Inc. also designs and fabricates (forms, molds, vulcanizes) our radiation resistant SEALFAST® Active Inflatable and Mechanical seals at our engineering and production facility, allowing us to optimize the right elastomer for any shape, size, pressure, or material in rapid lead-times.


Outage equipment hatches are primarily found in use at nuclear power plants, government nuclear research facilities, fuel processing or storage sites, and even in smaller commercial reactor service. In all of these applications, operators utilize temporary equipment hatches to increase overall site and environmental safety. Additionally, users who employ these barrier products can take advantage of significant cuts in planned outage time and are also open to reaping additional bonuses during regulatory reviews.

Have Specific Requirements?

We specialize in custom solutions! Take a look at a few of our proven custom solutions or let us know your requirements. Our engineers and production staff are equipped to travel around the world at a moment’s notice to assist you with your needs!

Let's Talk!

Contact us today to discuss our rates or to book an appointment with one of our engineers. 


MRD Nuclear Outage Equipment Hatche (OEH’s) can be provided in a wide variety of configurations, specially tailored to meet existing site infrastructure, installation, functional, and regulatory requirements (some of these designs are detailed in the slideshow above): hatches that are integral and welded to the containment access tube, hatches that lock into the tube with integral restraint screw dogs, hatches that support and restrain off of other nearby infrastructure (missle door supports), roll in place hatches that bolt up to existing permanent hatch bolts or toggle bolts, concrete anchor restraint rings or structures, and more! We can provide SEALFAST® Inflatable or Mechanical Seals at any sealing interface in nearly any size or shape (automated or manual actuation, with sensory monitoring). Hatches can be provided with internal doors, manways, piping/utility penetrations, or smaller removable hatches. Units can be designed to direcly interface with trolley rails, drive through equipment ramps, and other nearby installed lifting and handling systems. We can also integrate or provide permanent weld-in sections, where allowed, to optimize outage transport activities as well as facilitate more rapid hatch installations where existing infrastructure is limited. Units can be built (and shipped) in single section barriers or modular, sectional, pressure sealing sections for assembly onsite.


Most designs are provided standard to Mechanical Research & Design, Inc. Engineering Design Manual for sealing and structural systems. Designs can also be provided to meet AISC® structural and seismic codes, ASME® pressure codes, and Aluminum Association Handbook® structural design.


MRD Nuclear has provided outage equipment hatches in a wide range of sizes and shapes. We have fabricated and tested OEH’s to over 20 feet in diameter. Overall hatch shapes have ranged from circular to rectangular… to irregularly shaped doors and hatches. Since we fabricate our own sealing elastomers, we can traverse nearly every difficult turn and corner we encounter. We can also conform our products to work with any existing infrastructure geometry with restricted clearances/access, as well as provide modular sealed section assemblies where full size barrier installation is impossible.


While most outage equipment hatches are designed for pressure sealing service based on idle reactor boil-off safety pressures (5-10 psi), designs are available to over 100 psi as well as for vacuum pressure service.


MRD Nuclear outage equipment hatches typically supplied with our own SEALFAST® Active Inflatable and Mechanical seals. These durable, engineered, and field-tested sealing products are typically found on the sealing elements between our barriers and the existing structure, on hinged doors or access panels, and on process or utility penetrations. We can fabricate radioactive resistant seals to almost any cross-section, overall size, and shape, quickly, as we design and fabricate seals onsite in our SEALFAST® Elastomers department. This means, we are not limited, in a conventional sense, in size, scope, function, or material of seals – we can design for total optimization! Most elastomers are EPDM for nuclear use, however, we have materials in nitrile, natural rubber, urethane, and other compounds that can be compatible contingent on dosage.


Haches as well as other provided support infrastructure and accessories can be provided in standard epoxy coated carbon steel, aluminum, stainless steel, and other materials or coatings based upon request.


OEH’s can come with a wide variety of accessories including process penetrations, ramps, automated operation doors, lifting accessories, and more:


*DOORS AND INTERNAL HATCHES: MRD Nuclear can provide a wide variety of shape and size doors and hatches, with many accessory options, including: hinge mounts, manual operation and locking operation, automated assist open/close and locking features, pressure and limit switch sensors and alarms, SEALFAST® Inflatable or Mechanical seal options, and more!


*HATCH PENETRATIONS: We can provide user-specified quantities and sizes of process piping penetrations, power cable glands, utility hose or or piping connections, communications cable pass-throughs, and more!


*RAMPS AND CONTROLS: We have provided manual installation and automated operation ramp systems for wide heavy load truck transit in and out of containment, some designs exceeding 90 tons! MRD Nuclear offers static lift in place ramps, fold up ramps, safety railing, and winch controlled ramp systems that assist in rapid hatch isolation / missle door closure. We can also supply ramp winch, pully, and control systems integral to the hatch system for ease of use and operation.


*LIFTING / INSTALLATION ACCESSORIES: We specialize in lifting accessories and adaptors for fork truck and tele-handler installation of full single section barriers as well as for modular sectioned assemblies. MRD also provides fully certified lift beams and lift assemblies for picking, pulling, and tugging assemblies. We are also experienced in outdoor rolling assembly design to facilitate those installations.


*STORAGE FRAMES AND CONTAINERS: We can provide long term storage stands, fully enclosed storage containers, and shipping frames for section and full shipment of barrier products. MRD Nuclear has shipped 20′ plus full diameter hatches across the country in customized shipping frames with coordinated logistics.


Mechanical Research & Design, Inc. has been successfully developing solutions and supporting our customers in the nuclear industry for decades. We balance field test products with cutting edge research & development, producing industry leading tools in the nuclear power, research, and defence industries. We design, develop, fabricate, assemble, and test at our manufacturing production facility in Manitowoc, Wisconsin and travel worldwide to support our customers during all phases of the project. We also engineer and fabricate our SEALFAST® Elastomers, in-house, to offer the highest quality, most rapid turnaround sealing solutions for our outage equipment hatches, from standard to customized designs. If you’d like to learn more about MRD Nuclear options and what they can do for you, call today, and speak to one of our applications engineers!


• See our other Nuclear Tool Products here. 
• Interested in our Underwater Construction Products?
• See our Annular Sealing Products. 

Outage Equipment Hatch, Nuclear Hatch, Radiation Hatch, Nuclear Door, Radiation Door, Radiation Block, Radiation Shield, Nuclear Seal, Radiation Seal, Hot Box, Hot Cell, Air Lock, Nuclear Air Lock, Radiation Air Lock, Temporary Bulkhead, Tunnel Bulkhead, Tunnel Barrier, Isolation Barrier, SEALFAST® Products, MRD Nuclear | Large Isolation Barriers and Bulkheads | Mechanical Research & Design, Inc., Manitowoc Wisconsin U.S.A.