11

NN--416416--44& IWA& IWA--45404540

NDE vs. HydrotestingNDE vs. Hydrotestingvs. Structural Integrityvs. Structural Integrity

Rick SwayneRick Swayne

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History of Case NHistory of Case N--416416•• In 1994, NIn 1994, N--416416--1 eliminated hydrostatic testing, 1 eliminated hydrostatic testing,

but added 1992 Section III NDE.but added 1992 Section III NDE.–– This was a compromise with the NRC desire for a This was a compromise with the NRC desire for a

volumetric examination of all welds.volumetric examination of all welds.–– The NRC added root pass surface examination for The NRC added root pass surface examination for

Class 3 welds subject to surface examination, in Class 3 welds subject to surface examination, in SERsSERsand in R.G. 1.147, Rev. 12.and in R.G. 1.147, Rev. 12.

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History of Case NHistory of Case N--416416•• In 2000, NIn 2000, N--416416--2 added coverage of fabrication 2 added coverage of fabrication

welds.welds.–– The NRC deleted the extra root pass surface The NRC deleted the extra root pass surface

examination for Class 3 welds subject to surface examination for Class 3 welds subject to surface examination, in R.G. 1.147, Rev. 13.examination, in R.G. 1.147, Rev. 13.

•• In 2005, NIn 2005, N--416416--4 deleted the additional 1992 4 deleted the additional 1992 Section III NDE.Section III NDE.–– The NRC has not yet endorsed NThe NRC has not yet endorsed N--416416--4 in R.G. 1.147.4 in R.G. 1.147.

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History of IWAHistory of IWA--45404540

•• In the 1999 Addenda, IWAIn the 1999 Addenda, IWA--4540 was 4540 was revised to incorporate Nrevised to incorporate N--416416--2. This 2. This revision incorporated the 1992 Section III revision incorporated the 1992 Section III NDE requirements from Case NNDE requirements from Case N--416416--2.2.–– The NRC endorsed the revised IWAThe NRC endorsed the revised IWA--4540, in 4540, in

2002, without limitation (no root2002, without limitation (no root--pass exam).pass exam).

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HistoryHistory of IWAof IWA--45404540•• In the 2003 Addenda, IWAIn the 2003 Addenda, IWA--4540 was 4540 was

revised to incorporate Nrevised to incorporate N--416416--4. This 4. This revision deleted the 1992 Section III NDE revision deleted the 1992 Section III NDE requirements.requirements.–– The NRC endorsed the revised IWAThe NRC endorsed the revised IWA--4540, in 4540, in

2004, without limitation (no root2004, without limitation (no root--pass exam pass exam or other NDE).or other NDE).

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PresentPresent

•• The NRC has indicated a desire to add The NRC has indicated a desire to add more NDE, if leakage testing is substituted more NDE, if leakage testing is substituted for a hydrostatic test, following for a hydrostatic test, following repair/replacement activities.repair/replacement activities.

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NDE vs. HydrotestingNDE vs. Hydrotesting

•• What is the relationship between test What is the relationship between test pressure and NDE?pressure and NDE?

•• What value does the elevated pressure of What value does the elevated pressure of a hydrotest provide?a hydrotest provide?

•• What are the added costs of hydrotesting?What are the added costs of hydrotesting?•• What is the costWhat is the cost--benefit relationship?benefit relationship?

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Value of HydrotestingValue of Hydrotesting

•• Hydrotesting is ALWAYS performed at a pressure that is Hydrotesting is ALWAYS performed at a pressure that is less than the material yield strength at all locations in less than the material yield strength at all locations in the component.the component.

•• Therefore, hydrotesting NEVER proves structural Therefore, hydrotesting NEVER proves structural integrity integrity –– it proves only leak tightness.it proves only leak tightness.

•• The required pressure for a hydrotest has no relationship The required pressure for a hydrotest has no relationship to the NDE required by ANY Construction Code (Section to the NDE required by ANY Construction Code (Section I, III, IV, VIII, X, or XII, or B31.1, B16.34, etc.), or I, III, IV, VIII, X, or XII, or B31.1, B16.34, etc.), or Section XI.Section XI.

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NDE vs. Structural IntegrityNDE vs. Structural Integrity

•• Is there a relationship between NDE and Is there a relationship between NDE and structural integrity?structural integrity?

•• YES!YES!–– The reduced thickness permitted by Section III, NBThe reduced thickness permitted by Section III, NB--

3000 MUST be compensated by increased NDE.3000 MUST be compensated by increased NDE.–– The additional thickness required by B31.1 and The additional thickness required by B31.1 and

Section III, NC/NDSection III, NC/ND--3000 does not require additional 3000 does not require additional NDE. The increased design factor compensates for NDE. The increased design factor compensates for the reduced NDE.the reduced NDE.

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Cost of HydrotestingCost of Hydrotesting

•• Hydrotesting requires special valve lineups, and Hydrotesting requires special valve lineups, and special pumps.special pumps.

•• Hydrotesting can not be performed at some Hydrotesting can not be performed at some locations without unloading fuel.locations without unloading fuel.

•• Hydrotesting usually extends outage times.Hydrotesting usually extends outage times.•• Hydrotesting sometimes requires freeze seals or Hydrotesting sometimes requires freeze seals or

valve replacement.valve replacement.

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HydrotestingHydrotestingCostCost--Benefit RelationshipBenefit Relationship

•• Is hydrotesting worth the added cost?Is hydrotesting worth the added cost?–– NEVER!NEVER!

•• Is some compensation for the reduced Is some compensation for the reduced pressure warranted?pressure warranted?–– Only if safety is compromised.Only if safety is compromised.

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Effects of Reducing Test PressureEffects of Reducing Test Pressure

•• ASME SC XI performed an informal survey.ASME SC XI performed an informal survey.•• One participant reported that, in one case, slight One participant reported that, in one case, slight

weepage occurred during a hydrotest, that was weepage occurred during a hydrotest, that was not visible at nominal operating pressure. The not visible at nominal operating pressure. The leakage resulted from porosity that was slightly leakage resulted from porosity that was slightly expanded by the additional pressure.expanded by the additional pressure.

•• No other leakage at the hydrotest pressure was No other leakage at the hydrotest pressure was reported.reported.

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Effects of Reducing Test PressureEffects of Reducing Test Pressure

•• ASME SC XI concluded thatASME SC XI concluded that–– Hydrotesting is not related to structural Hydrotesting is not related to structural

integrity.integrity.–– There is no safety benefit associated with There is no safety benefit associated with

hydrotesting in a nuclear power plant.hydrotesting in a nuclear power plant.