Normal and Emergency Operations

The cylindrical tank failed on October 20, 1944, and released 147,000 ft of LNG. Much of the liquid vaporized, but some of it also overflowed the enclosed area and entered the surrounding storm sewers. As there were numerous ignition sources in the vicinity, the vapor-air mixtures ignited and produced flames that were reported to extend to a height of at least 2800 ft these also ignited the explosive mixtures within the sewers and weakened the uninsulated columns of one of the spherical tanks. The columns collapsed and spilled the contents of this tank about 20 min after the failure of the cylindrical tank. Fire damage extended over 1/4 mile from the cylindrical tank  

Much can be learned from a review of the complete report of the Cleveland disaster. Of particular significance were site location, choice of tank material (3 % nickel steel—this reportedly had the lowest impact strength of all materials tested), lack of adequate dikes, and presence of ignition sources. These items have been considered in greater detail in recent years at present a number of huge LNG plants are in operation and tankers have been developed for the transport of this commodity. 

Numerous other case histories of interest may be found in the MCA compilation, in the review of liquid hydrogen hazards by Wein-traub, and in the article on oxygen plant safety by McKinley and Himmelberger, and that on hazards in cryogenic systems by Van Dyke. An analysis of a number of accidents indicates the following 

Mechanical failure of the containment vessel, piping, or auxiliary components (brittle failure, hydrogen embrittlement, freeze-up). 

Reaction of the fluid with a contaminant (e.g., oxygen plus a hydrocarbon). 

---

If operating procedures need to be developed from scratch, this could account for a considerable portion of the pre-startup work. If current, valid standard operating procedures exist, and the toll is only introducing a new set of batch instructions, the task becomes simpler. However, it is recommended that the new batch instructions are reviewed simultaneously with the existing startup, shutdown, normal and emergency operating procedures for the equipment to help ensure potential process deviations are examined and addressed. 

Designs and systems should minimize potential harmful exposures in both normal and emergency operations. This consideration affects the location of normal and emergency drains and vents. 

Cryogenic fluids can be used safely in the laboratory or industrial plant if all facilities are properly designed and maintained, and if the personnel are adequately trained and supervised. However, consideration must be given to both normal and emergency operations. This holds true for new facilities as well as for those that have been modified to handle cryogenic fluids. 

As with laboratory operations, basic safety considerations in low-temperature plants and test sites are similar to those in many chemicalprocessing plants. For example, many of the items considered by Kintz and Hill in their study of safety at gas-processing plants are also applicable to cryogenic facilities. Many of these are also discussed by Armistead, Liston, and Cost." They are considered here under six categories—design concepts, maintenance, normal and emergency operations, personnel protection, and plant and test site protection. 

Two members of the Working Group visited Hinkley Point B on 12-13 February 1987 to study some of the normal and emergency operational procedures on an Advanced Gas-cooled Reactor station. 

Normal and emergency operating procedures should be developed and/or improved to reduce incident initiation and mitigate accidents during shutdown modes. 

The kind, amount, and distribution of protective devices, as well as laboratory practices for normal and emergency operation, vary considerably in detail from laboratory to laboratory. This very brief introduction to the subject of the handling and manipulation of large amounts of alpha activity is intended to serve mainly as a warning to the uninitiated. The subject of enclosures for radioactive materials is treated fully in a review by Garden and Nielsen. 

The reduced power density of the core ensures low thermal loads under normal and emergency operating conditions. The chosen water/uranium ratio provides for favourable fuel cycle economy. 

Normal and emergency operation of the RCS requires several support functions to maintain water inventory, purify and treat primary coolant, remove residual heat after a plant shutdown, provide cooling water to pumps and motors, supply ventilation air, and provide... 

Tests are necessary to investigate the processes of core residual heat transfer to the reactor vessel and then to atmospheric air for normal and emergency operation conditions of the MBRU-12 ... 

Internal hazards considered in the APIOOO PRA are those events whose cause is external to systems associated with normal and emergency operations situations. Some internal hazards may not pose a significant threat of a severe accident. Some internal hazards are considered at the design stage and have a sufficiently low contribution to core damage fi-equency or plant risk. 

Validation and testing of thermal-hydraulic characteristics of the in-vessel natural circulation circuit under normal and emergency operating conditions... 

Validation of a passive cool down concept by performing complex experiments to investigate modes of sodium flow in the primary circuit and air circulation outside the reactor module, as well as sodium and air hydrodynamics under conditions typical of normal and emergency operation... 

Description of the safety management system, including plans and procedures in place for normal and emergency operations. 

---