ASME/BPVC - CASE N-730
N-730 Roll Expansion of Class 1 Control Rod Drive Bottom Head Penetrations in BWRs Section XI, Division 1 Supp 4
| Organization: | ASME/BPVC |
| Publication Date: | 1 January 2007 |
| Status: | inactive |
| Page Count: | 2 |
scope:
This Case applies to use of mechanical roll expansion for the purpose of sealing leakage from cracks detected in the following locations:
(a) CRD stub tube base metal
(b) CRD stub-tube-to-housing
(c) CRD stub-tube-to-vessel attachment weld
(d) CRD housing-to-vessel attachment weld (BWR/6)
This Case shall not be used when leakage is due to through-wall cracking in the housing.
The following conditions shall apply to this Case:
(a) Housing material: Any P-No. 8 or P-No. 43
(b) Vessel material: Any P-No. 3
(c) Measured percent wall thinning: 3.5% - 6.5%
(d) Roll-band length shall not exceed 6 in. (150 mm)
(e) Minimum roller top/bottom end radius ¾ in. (19 mm)
(f) Ratio of housing specified minimum yield strength to vessel head specified minimum yield strength < 1.0
(g) If more than one roll is required to achieve the required roll-band length, the minimum overlap for each roll shall be at least 0.5 in. (13 mm).
(h) Rollers shall be lubricated.
The provisions of IWA-4140, IWA-4150, IWA-4170, and IWA-4310 shall be met.
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