Document: NUREG-0800
Document ID: 042bc5c0-5de0-44b4-9599-6c131e20eb7a
Document Type: srp
Title: FUNCTIONAL DESIGN OF CONTROL ROD DRIVE SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070413.pdf
Revision Date: 2023-06
Chapter: 4
Section ID: 4.6
CFR Part: 
CFR Title: 

Content:
r function of the cooling system in PWRs is to cool the drive mechanism and remove heat from the CRDS motors to preclude motor burnout or damage. Failure of a CRDS motor could result in a rod drop. In BWRs, the major function of the cooling water is to cool the drive mechanism and its seals to preclude damage resulting from long-term exposure to reactor temperatures. The control rod drive hydraulic system includes the cooling function as part of its design. The ASBSRXB reviewer confirms 56 by failure modes and effects analysis that the cooling system is capable of maintaining the CRDS temperature below the applicant's maximum temperature criterion. The ICSBHICB reviewer in SRP Section 7.2 confirms that there are sufficient 57 instrumentation and controls available to the reactor operator to provide information in the control room to monitor the CRDS conditions, including the more significant parameters such as coolant flow, temperature, and pressure and stator temperature. 4. In coordination with the EMEB , the ASBSRXB reviews the functional tests of the 58 59 CRDS as related to rod insertion and withdrawal and scram operation and time. The reviewers check the elements of the test program to ensure that all required thermal-hydraulic conditions have been included for all postulated operating conditions. Experimental verification of system operation where a single failure has been assumed should be included in the test program, e.g., accumulator leakage for hydraulic CRDS and stuck rod operation. 5. The reactivity control systems are evaluated to verify that redundant reactivity control systems are not vulnerable to common mode failures. The ASBSRXB identifies the 60 common mode failures and the ICSBHICB, EMEB, and CMEBEMCB assist the 61 ASBSRXB reviewer in connection with their responsibilities in SRP Sections 7.4, 62 3.9.4, and 9.3.4 or 9.3.5, respectively. 6. For BWR plants that have a scram discharge volume (SDV), the SRXB reviews the system capabilities and