Intermediate range monitors

As startup progresses and the count rate approach the top of the meter range (about 10 cps), the counters are withdrawn downward to give a drop in apparent count rate. Criticality normally occurs before movement of the counters is necessary. The counters can be motor driven to any position within their limits of travel however, two or three selected positions will provide the necessary range to achieve criticality and provide overlap with the intermediate range monitors. 

When the reactor reaches the power range, the counters are moved to a position approximately 2 ft (0.61 m) below the core. This places the counters in a low neutron flux so that bumup and activation of the counters are minimized. 

These fission chambers are also withdrawn during full power operation to maintain their expected life and to reduce activation. They are positioned with drive mechanisms similar to those used for the source range fission counters. 

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A laboratory and on-reactor evaluation of three commercial Intermediate Range Monitors has been completed. Although none of the Instruments evaluated have all the features desired for a reactor process instrument, at least one of the instruments will satisfy the requirements with minor modifications. 

A typical Intermediate Range System for reactor scifety circuit use could consist of three Intermediate Range Monitors with log-level and reactor period readout and trips, through compensated ion chambers and associated power supplies and three reactor hole facilities with shield plug, bonnets, etc. 

Specifications are being prepmd foi the purchase of Intermediate Range Monitors. It is planned to require a production prototype prior to the acceptance of production quantities. 

The linear rate system should be Interlocked to bypass the exponential rate trips of the Intermediate Range Monitor after a power level of 10 has been reached This will reduce the possibilities of a failure in the Intermediate Range Monitor period func tlon causing a spurious scram when the Instrument Is no longer needed for exponentleil rate protection. 

Level trips vould not need to be set for "cold" and "hot" startups as presently done because the Beckmans will not be required for rate control after the Intermediate Range Monitor and Linear Rate-of-Rlse equipment is installed. 

Ihe present Beckmai s will be retained as the bottom neutron flux monitors in the any two-out-of-four tripplng network. TOie level trips of the Intermediate Range Monitor will be in a two-out< of-three network at the B, D, DR, F, and H Reactors where three channels will be installed. An "any-two-out-of-four" tripping network should be used at C and the K Reactors. 

It should be acknowledged that the function of such a system is approached with the above system (combinations of Intermediate Range Monitors and present Beckmans without the... 

Because of the addition of the top neutron flux monitoring system in the form of the level trip of the Intermediate Range Monitor, adequate protection can be still maintained with a reduced Zone Temperature Monitor (especially when considering... 

GE SIL 409R2 (02/08/02) Inspection of SRM/IRM Dry Tubes Provides information and recommendations on the cracks found in Intermediate Range Monitor (IRM) and Source Range Monitor (SRM) dry tubes. [6.201... 

Three ranges are used to monitor the power level of a reactor throughout the full range of reactor operation. The intermediate range makes use of a compensated ion chamber. 

Installation of three channels of Intermediate Range (Nuclear) Monitors is Justified for reactor uid nuclear safety Improvement. Gamma compensated Ion chambers would be insteilled In the top portions of... 

Present Model RXG and R G-2 Beckmans are being replaced with nev units because of obsolesence and maintenance difficulties. The combination of these inits and the level trip from the Intermediate Range (Nuclear) Monitoring System will provide adequate high level nuclear protection. The octant monitoring concept is dropped from further consideration at this time. 

Zone Temperature Monitors are necessary to provide geometrical coverage of the reactor in addition to the Nuclear Monitoring from item 5 above. However, a reduced number of points can provide this protection compared to the present numbers at the old reactors with the addition of the Intermediate Range (Nuclear) Manitoring level trips in the top of the reactor. Three channels of Zone Temperature Monitor are suggested for an initial system composed of 22, 17 and 22 points respectively at the old reactors. The... 

Laguna Verde Unit two started three fuel cycles after the unit one, during the construction process and start-up program of unit one some of the components of unit two were used as spare parts of unit one, for that reason during construction program of unit two such components were required but such components were out of the market, companies closed, or new advanced systems were developed for such purposes. That was the case of the Transverse In core Probe (TIP), Source (SRNM) and Intermediate range (IRNM) neutron monitoring systems. 

The original concept for neutron monitoring includes three systems. Source range. Intermediate range and Power range. During start-up the operator has to select and operate... 

Interlocks are used on the intermediate range neutron monitors to ensure that all units are operating properly and on the proper range. Control rod withdrawal is blocked if the ratio of reactor power to recirculation flow exceeds a predefermined value. 

BF3 proportional counters are highly sensitive to neutrons, and usually are used in a pulse countii mode to monitor the neutron flux and the reactor period (rate at which the neutron flux changes) in the source (start up) range. Even it is not usual, BF3 detectors can also be used as compensated ionization chambers, to monitor the neutron flux level and the reactor period in the intermediate range. 

The availability of lasers having pulse durations in the picosecond or femtosecond range offers many possibiUties for investigation of chemical kinetics. Spectroscopy can be performed on an extremely short time scale, and transient events can be monitored. For example, the growth and decay of intermediate products in a fast chemical reaction can be followed (see Kinetic measurements). 

Applications The differential optical absorption spectrometer has been used to monitor concentrations of gases or intermediate compounds such as SO, NO, O5, HCHO, HNO, CS, NO, and OH in the atmosphere.In atmospheric measurements with open paths of 100 to 1000 m, a detection limit of about 1 ppb can be achieved. In the emission measurements, the path length across the duct or the plume can range in meters. 

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