Primary vessel and internals

Fermi (USA) internal-visual with optical aids (limited extent)  

JSFR-1500 (Japan) USV with free-moving vehicle VI, US, FV 

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IN-SERVICE INSPECTION PROVISIONS (cont.) 12.1. Primary vessel and internals... 

Provision for routine ISI of inside of primary vessel and internal stmcture Provision for routine ISI of outer surface of primary vessel... 

Nuclear Boiler Assembly. This assembly consists of the equipment and instrumentation necessary to produce, contain, and control the steam required by the turbine-generator. The principal components of the nuclear boiler are (1) reactor vessel and internals—reactor pressure vessel, jet pumps for reactor water circulation, steam separators and dryers, and core support structure (2) reactor water recirculation system—pumps, valves, and piping used in providing and controlling core flow (3) main steam lines—main steam safety and relief valves, piping, and pipe supports from reactor pressure vessel up to and including the isolation valves outside of the primary containment barrier (4) control rod drive system—control rods, control rod drive mechanisms and hydraulic system for insertion and withdrawal of the control rods and (5) nuclear fuel and in-core instrumentation,... 

The ongoing joint United States/Russian Federation project to develop and construct a version of the GT-MHR to consume surplus weapons plutonium is an important element of commercial GT-MHR development. The major systems, structures and components of the GT-MHR, including the power conversion system, reactor vessel and internals, and reactor building, can be developed and demonstrated through this project. The primary alterations to the plutonium consumption design are expected to be in the reactor core and possibly the reactor cavity cooling system, with the remainder of the commercial GT-MHR drawing directly from the plutonium consumption version. 

When the internal design pressure of a container exceeds 15 psig (101.3 kPa), it is called a pressure vessel. The ASME Boiler and Pressure Vessel Code is one of the primary standards used throughout the world to ensure safe storage vessels. Various substances, such as ammonia (qv) and many hydrocarbons (qv), are frequently stored in spherically shaped vessels that are often referred to as tanks. Most often the design pressure is 15 psig (101.3 kPa) or above. These are really spherical pressure vessels and fall under the rules of the ASME Boiler and Pressure Vessel Code. Discussion of pressure vessels are available (5,6) these are not covered in detail herein. 

First, we need to define generally what we are talking about A pressure relief device is any device that can purge a system from an overpressure condition. More particularly, an SRV is a pressure relief device that is self-actuated, and whose primary purpose is the protection of life and equipment. Through a controlled discharge of a required (rated) amount of fluid at a predetermined pressure, an SRV must prevent overpressure in pressurized vessels and systems, and it operates within limits which are determined by international codes. An SRV is often the final control device in the prevention of accidents or explosions caused by overpressure... 

After three years preparation, the TV inspection of the primary circuits internals has been successfully issued in April 2001. The Novatome division of Framatome-ANP, completed the extensive non-destructive inspection program requested by the Phenix plant with an inspection of the primary circuit internals. Included in its service package were the setting up of the TV inspection — which required the partial draining of the primary-side sodium — the supervision of the supply of various materials needed to be developed and qualified, and the actual carrying out of die inspection. Justification studies for the inspection were carried out at the same time focusing on the thermalhydraulic, safety and radiation protection aspects affected by the lowering of the sodium level in the primary vessel. 

Under the 9th Decommissioning Permit, the reactor vessel with its internals, the primary shield, and the biological shield are to be dismantled. A Europeanwide limited tendering procedure was first run for these activities, and at last the contract was made with Westinghouse Reaktor Germany. 

The inner container is the primary sodium tank. As previously stated, the tank is equipped with a safety vessel and placed in a massive concrete structure. The roof of the tank and all penetrations would be designed to withstand about 10-15 psig positive internal pressure and would normally be held at 0 to 2 psig. During refueling, the pressure would be varied 5 psi. 

Concerns have been expressed about damage to primary systems and components as the result of excessive vibration. A major source of vibration for the NSSS is flow-induced vibration (i.e., water flowing through the Reactor Coolant System (RCS)). Flow-induced vibration can lead to damage to the reactor vessel internals and, potentially, interference with control rod movement. 

The reactor vessel is the container and support structure for the reactor core, the primary sodium, and the internal structures. These components provide shielding, flow passages, thermal barriers, sealing and restraint surfaces, and load transfer paths. The reactor vessel performs its support and containment functions during the temperature, pressure, and load variations which occur during its operating lifetime. The reactor... 

During reactor operation, the shield building protects personnel occupying adjacent plant structures and yard areas from radiation originating in the reactor vessel and primary loop components. Internal to the containment, the reactor vessel is shielded by the concrete primary shield and by the concrete secondary shield, which also surrounds the primary components. 

Primary containment is provided by the vessels and pipework of the treatment system. The system is designed to operate at pressures only slightly above atmospheric this minimises the rate of loss in the event of a leak. Secondary containment is provided by the building stmcture of the Nuclear Island. The gaseous radwaste system will be located internally, with no points where there could be leakage directly to external environment. Further details of the system are provided in the Environment Report (Section 3.3), and the EDCD section 11.3, (Reference 14.2). 

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