Document: NRC Regulatory Guide
Document ID: d0bc0d48-8edb-492d-b813-53be9418b4aa
Document Type: regulatory_guide
Title: Maintenance of Water Purity in Boiling Water Reactors (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740192.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.56
CFR Part: 
CFR Title: 

Content:
ter. The condensate de mineralizers remove insoluble corrosion products by filtration and remove dissolved ionic materials, i.e., metals and salts, by ion exchange. They also afford limited prbtection from large condenser tube leaks until corrective action is initiated. The feedwater passes through the feedwater heaters and enters the reactor at about 385°F (196°C). Since there is no "blowdown," the reactor water concentrates all the soluble and insoluble materials that enter via the feedwater. In BWRs, the reactor water cleanup sys tem performs the blowdown function by removing soluble and insoluble impurities from the reactor wa ter. Thus, extremely pure feedwater is provided by the equipment as necessary. In BWRs, the various heat exchangers of auxiliary systems are barriers between high-purity reactor water and cooling water that may be contaminated with dissolved or suspended solids. Main condenser leakage is a potential source of such contaminants. Such leakage should be minimized by proper condenser design and by provid ing for reliable detection' of leakage. The rate of con denser leakage may be estimated from measurements of the electrical conductivity of the water in the con denser hotwell or in the line between the hotwell and the demineralizer. A meter with sufficient range to measure all water conductivity levels at least up to the limiting conditions of the technical specifications that require immediate shutdown of the reactor should be provided. The condensate demineralizer system is provided between the condenser and the reactor vessel to re duce impurities from condenser leakage and other sources to an acceptable level. A typical condensate demineralizer consists of several parallel ion ex change units, the resins in which serving both to remove ionic impurities and to filter out suspended solids. Depending on the flow rate, type of resin, cleanli ness of resin of BWR full-flow demineralizer sys tems, and type of ions in the coolant, total