Document: NRC Regulatory Guide
Document ID: 7bdfde6b-2c09-49db-8a3f-863eab24747e
Document Type: regulatory_guide
Title: Control of Combustible Gas Concentrations in Containment + HISTORY - HISTORY 08/2002 – DG-1117 , Proposed Revision 3 Prior to the issuance of DG-1117, RG 1.7 was entitled "Control of Combustible Gas Concentrations in Containment Following a Loss-of-Coolant Accident," to reflect its narrower original scope
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0222/ML022210067.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.7
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CFR Title: 

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criteria if they: 1. Comply with the Category 3 design and qualification criteria of Regulatory Guide 1.97 (Ref. 8) for monitors used as diagnostic or backup indicators. 2. Comply with the Category 2 power source design and qualification criteria as specified in Table 1 of Regulatory Guide 1.97 (Ref. 8). The above provisions can be met with a program based on compliance with a pre-specified, structured program of testing and calibration; alternatively, these items can be met with a less-prescriptive, performance-based approach to assurance of the hydrogen monitoring function. Such an approach is consistent with SECY-00-191, "High-Level Guidelines for Performance-Based Activities" (Ref. 9). Specifically, assurance of the reliability, availability, and capability of the hydrogen monitoring function can be derived through tracking actual reliability performance (including calibration) against targets established by the licensee based on the significance of this function, 5 which is determined on a plant-specific basis. Thus, for hydrogen monitoring, it is acceptable to accomplish the functions of servicing, testing, and calibration within the maintenance rule program provided that applicable targets are established based on the functions of the hydrogen monitors delineated above. Section 50.44 also requires that hydrogen monitors be functional. Functional requirements can be found in TMI Action Item II.F.1, Attachment 6, in NUREG-0737 (Ref. 10), which states that hydrogen monitors are to be functioning within 30 minutes of the initiation of safety injection. This requirement was imposed by confirmatory orders following the Three Mile Island Unit 2 accident. Since that requirement was issued, the staff has determined that 30 minutes can be overly burdensome. Through the “Confirmatory Order Modifying Post-TMI Requirements Pertaining to Containment Hydrogen Monitors for Arkansas Nuclear One, Units 1 and 2” (Ref. 11), dated September 28, 1998, the staff developed a