Document: NUREG-0800
Document ID: 07e6bf87-51bb-4023-80a2-2a67ca4a9f80
Document Type: srp
Title: Revision 3 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070740319.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6
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Content:
le calculated offsite radiological consequences and ensure that emergency core cooling system (ECCS) effectiveness is not degraded by a reduction in the containment back pressure. Purge system designs acceptable for nonroutine use during normal plant operation can be achieved with additional purge lines. The size of these lines should be limited so that in a LOCA, assuming the purge valves are open and subsequently close, the radiological consequences calculated in accordance with Regulatory Guides 1.3 and 1.4 would not exceed 10 CFR Part 100 guideline values. Also, the maximum time for valve closure should not exceed five seconds so that the purge valves would be closed before the onset of fuel failures following a LOCA. Similar concerns apply to vent system designs. The size of the purge lines should be about eight inches in diameter for pressurized-water reactor (PWR) plants. This line size may be overly conservative from a radiological viewpoint for the Mark III boiling-water reactor (BWR) plants and the high-temperature gas reactor (HTGR) plants because of containment or core design features; therefore, larger line sizes may be justified. For any proposed line size, however, the applicant must demonstrate that the radiological consequences of a LOCA would be within 10 CFR Part 100 guideline values. In summary, the acceptability of a specific line size is a function of the site meteorology, containment design, and radiological source term for the reactor type (e.g., BWR, PWR, or HTGR). BTP 6-4-3 Revision 3 - March 2007 B. BRANCH TECHNICAL POSITION The systems that purge the containment for the reactor operational modes of power operation, startup, hot standby and hot shutdown (i.e., the on-line purge system) should be independent of the purge system used for the reactor operational modes of cold shutdown and refueling. 1. The on-line purge system should be designed in accordance with the following criteria: A. GDC 54 requires that the reliability and performance