Document: NUREG-0800
Document ID: d4441736-a9bb-45c2-8d16-d23e8312ab08
Document Type: srp
Title: CHEMICAL AND VOLUME CONTROL SYSTEM MALFUNCTION THAT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070717.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.4.6
CFR Part: 
CFR Title: 

Content:
these to the limiting safety system settings included in the proposed technical specifications. The descriptions of moderator dilution transients presented in the SAR are reviewed by RSBSRXB regarding the occurrences leading to the initiating events. The sequence of events, 34 from initiation until a stabilized condition is reached, is reviewed to ascertain: 1. The extent to which normally operating plant instrumentation and controls are assumed to function. Particularly important are the alarms which alert the operator to the unplanned boron dilution. 2. The extent to which the plant and reactor protection systems are required to function. 3. The credit taken for the functioning of normally operating plant systems. 4. The operation of engineered safety systems that is required. 5. The extent to which operator actions are required. 6. The appropriate margin for malfunctions, such as stuck rods are accounted for. The RSBSRXB reviewer confirms that analyses are included for a boron dilution incident 35 occurring during each of the following plant initial conditions: refueling, startup, power operation (automatic control and manual modes), hot standby, and cold shutdown. The refueling condition should consider cases when the reactor vessel head is removed and the coolant is drained to the elevation of the hot leg piping. For each such incident reviewed, all possible causes must have been considered by the applicant and justification presented that the cause selected for analysis is the one that allows the operator the least time to take corrective action. With the aid of the EICSBHICB reviewer, the timing of the initiation of those protection, 36 engineered safety, and other systems needed to limit the consequences of each boron dilution incident to acceptable levels is reviewed. The RSBSRXB reviewer compares the predicted 37 variations of system parameters with various trip and system initiation setpoints. The ICSBHICB reviewer evaluates automatic initiation,