Document: NUREG-0800
Document ID: 3b207b59-015a-4145-be01-1f474ceec289
Document Type: srp
Title: MAIN CONDENSER EVACUATION SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070590.pdf
Revision Date: 2023-06
Chapter: 10
Section ID: 10.4.2
CFR Part: 
CFR Title: 

Content:
llows: 1. The MCES capacity should be consistent with the industry guidelines given in Reference 2. Either mechanical vacuum pumps or steam jet air ejectors may be used for hogging (startup) or normal evacuation of the main condenser. 2. The components of the MCES should be designed to Quality Group D as defined in Regulatory Guide 1.26 (Ref. 3) and to a nonseismic design classification. These quality 13 standards meet the requirements of 10 CFR 50.55a for water- and steam-containing components that may contain radioactive materials but are not part of the reactor coolant pressure boundary and are lessnot important to safety. 14 3. If there is a potential for explosive mixtures to exist, the MCES should be designed to withstand the effects of an explosion and the applicant should provide instrumentation 15 to detect and annunciate the buildup of potentially explosive mixtures, or provide dual instrumentation to detect, annunciate, and effect control measures to prevent the buildup of potentially explosive mixtures, as outlined in SRP Section 11.3, subsection II, "Acceptance Criteria," Item B. 6. Such a potential does not exist on systems designed to 16 maintain the steam content in all MCES components above 58% by volume in hydrogen-air mixtures or nitrogen content above 92% by volume in hydrogen-oxygen mixtures in all MCES components . 17 4. Provisions to control and monitor releases of radioactivity to the environment from the MCES must conform to the requirements of General Design Criteria 60 and 64 (Ref. 1) . 18 5. The design pressure and normal operational absolute pressure should be provided for MCES components containing potentially explosive mixtures. Technical Rationale The technical rationale for application of the acceptance criteria for the main condenser evacuation system is discussed in the following paragraphs.19 Compliance with GDC 60 requires that provisions be included in the nuclear power unit design to control suitably the release of radioactive