Document: NUREG-0800
Document ID: 506e7738-a99e-48a1-ab15-8e713f61d17f
Document Type: srp
Title: TURBINE BYPASS SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350085.pdf
Revision Date: 2023-06
Chapter: 10
Section ID: 10.4.4
CFR Part: 
CFR Title: 

Content:
REVIEW RESPONSIBILITIES Primary - Power Systems Branch (PSB) Secondary - None I. AREAS OF REVIEW The turbine bypass system (TBS) provides operational flexibility so that the plant may accept certain load changes without disturbing the nuclear steam supply system. The TBS is designed to discharge a stated percentage of rated main steam flow directly to the main condensers, bypassing the turbine. This steam bypass enables the plant to take step load reductions up to the TBS capacity without the reactor or turbine tripping. The system is also used during startup and shutdown to control reactor pressure for a boiling water reactor (BWR) and steam generator pressure for a pressurized water reactor (PWR). The TBS is not required for safe shutdown as the relief and safety valves are operated under emergency conditions. The system is not required to function as a heat sink for the prevention or mitigation of postulated accidents. Failure of the TBS during a load reduction or turbine trip would result in the actuation of the relief valves and possibly the safety valves. The PSB reviews the system from the branch connection at the main steam system to the main condensers. 1. The PSB reviews the TBS to determine that a failure of the system or system components will not have an adverse effect on essential equipment. 2. The PSB reviews the TBS functional requirements for both normal and abnormal operating conditions, and with respect to the following: (a) capability to isolate those portions of the system that could leak or malfunction; (b) capa- bility to perform adequate operational testing and inservice inspection; (c) to assure there are no adverse effects of postulated system piping failures on safety-related equipment; and (d) to reduce the possibility of reactor tran- sients due to inadvertent operation of the TBS from faults in the TBS instru- mentation and control. Rev. 2 - July 1981 USNRC STANDARD REVIEW PLAN Standard review plans are prepared for the guidance of the