Document: NRC Regulatory Guide
Document ID: 0b9a3243-ab39-402c-9f4b-215c6e4f79ab
Document Type: regulatory_guide
Title: Inservice Inspection of Ungrouted Tendons in Prestressed Concrete Containments (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740007.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.35
CFR Part: 
CFR Title: 

Content:
minimum re quired prestress level (as defined in the plant's Tech nical Specifications) at anchorage location for that group, the condition should be considered report able. 7.1.6. If from consecutive surveillances the measured prestressing forces for the same tendon or tendons in a group indicate a trend of prestress loss larger than expected and the resulting prestress ing forces will be less than the minimum required for the group before the next scheduled surveillance, ad ditional lift-off testing should be done to determine the cause and extent of such occurrence. The condi tion should be considered reportable. 7.2. During detensioning and retensioning of tendons (Regulatory Position 4.2), if the elongation corresponding to a specific load differs by more than 10% from that recorded during installation of the ten dons, an investigation should be made to ensure that the difference is not related to wire failures or slip of wires in anchorages. A difference of more than 10% should be considered reportable. 7.3. Failure in the tensile test at a strength or elongation value less than the minimum requirements of the tendon material should be considered report able. Other conditions that indicate corrosion (metal reduction) found by visually examining wire or strands should be considered reportable. 7.4. Reportable conditions for sampled sheath ing filler grease include: a. Water content b. Chlorides c. Nitrates d. Sulfides e. Reserve alkalinity (Base numbers) Exceeding 10% by wt Exceeding 10 ppm Exceeding 10 ppm Exceeding 10 ppm Less than 50% of the installed value or less than zero when the installed value was less than 5 f. Amount of grease replaced exceeds 5% of the net duct volume, when injected at the original installation pressure. g. Grease leakage detected during general visual examination of the containment exterior sur face. h. Presence of free water. 8. REPORTING TO THE NRC The reportable conditions listed in Regulatory Positions 7.1.3, 7.1.4, 7.1.5, 7.3,