1. ASME B&PV Code for In-Service Inspection of Nuclear Containment Buildings
Steven G. Brown, PE

2. Introduction Why is this of interest outside the nuclear industry?
Professional Development Hour
More than that – sharing information across various industries for improvement of the profession
Acknowledgements
K. R. Rao – Campion Guide to ASME Boiler and Pressure Vessel Code
Working Group Containment
Entergy
Disclaimer – The views presented are my own
If it’s right, it’s because my mentors got it right,
If it’s messed up, it’s probably my original idea.

3. Terminal Objective
At the conclusion of the class the engineer will have a basic understanding of the current rules requiring inservice inspection of nuclear containment vessels.
Key Points for folks outside the nuclear industry - illustrates interaction of the consensus body, regulator and industry to address inspection needs without being overly burdensome.

4. Enabling Objectives
State the purpose of containment vessel as used at commercial nuclear power plants in the US
Describe the general types of containment vessels currently used in the US commercial nuclear power industry.
State the difference between Class MC and Class CC components.
State the regulations requiring inservice inspection of nuclear containment buildings.

5. Enabling Objectives (cont)
Be able to state the section of ASME Code providing requirements for inservice inspection of Class CC components of nuclear containment vessels.
Discuss the type and frequency of inservice examinations for nuclear power plant containment vessels.

6. Purpose of Containment
10 CFR 50 - GDC 16 Containment Designs - Key design requirement for all U.S. commercial nuclear plants.
Establish an essentially leak tight barrier against the uncontrolled release of radioactivity into the environment
Ensure that the containment design conditions important to safety are cont exceeded for as long as required for post-accident conditions.

7. Typical Steel Containment Vessels
Steel Pressure Vessel – Class MC
Typically Carbon Steel
Approx. 40 to 60 psi
> 100 Feet Diameter
> 200 Feet Tall
Shell thickness 1.5” or more
Concrete Shield Building
Containment Design Diagrams on this and subsequent slides are from EPRI TM-102C

8. Typical Steel Containment Vessels
BWR Mark I – Class MC (typical)
Nominal 62 psi
Removable Head
Torus suppression pool

9. Typical Steel Containment Vessels
BWR Mark II (Shown) – Clas MC Typical
Nominal 45 psi
Removable Head
Suppression pool below
BWR Mark III (Not Shown) – May be MC or CC
Large vessel with internal drywell
Suppression pool internal around drywell

10. Typical Concrete Containment
Concrete Structure with steel liner
Concrete provides structural element – Class CC
Steel liner provides leak tightness – Class MC

11. Typical Concrete Containment
Post-Tensioned Concrete Containment
Concrete is kept under compression by a system of steel tendons
Tendon system and rebar are Class CC.

12. Provisions for Containment Inspections and Testing
10 CFR 50 - GDC 53 – Containments shall be designed to permit
Appropriate periodic inspection of all important areas, such as penetrations
An appropriate surveillance program
Periodic testing at containment design pressure of the leak tightness of penetrations

13. Philosophy of Containment Examination
ASME IWE and IWL define requirements for containment examination
Preservice
Inservice
Requirements based on Industry Experience and Environmental Conditions
Visual Examination of Containment
Testing for Tendons
Pressure / Leakage Testing per 10 CFR App J

14. History of Code Requirements
IWE 1st published 1981 (Class MC Components)
Weld Based Examinations
Very similar to rules for Class 1 and 2 nuclear components.
Subsequently addressed general degradation of surface areas
Incorporated by rulemaking (10 CFR 50.55a) in 1996
Required all containments to be treated as MC or CC
Included conditions for use
Conditions included:
General Visual once per period vs 1st per interval
Weld based exams not required
Inaccessible areas had to be evaluated if conditions were noted in accessible areas that indicated problems in inaccessible areas.
Rulemaking provided for expedited implementation schedule – utilities had to incorporate the rules earlier than the next interval update.

15. History of Code Requirements
IWL 1st published 1988 (Class CC Components)
Provided rules for examination of concrete surfaces
Similar to regulatory requirements already in Regulatory Guides 1.35 and
Regulatory Guides only required for post tensioned containments
Incorporated by rulemaking (10 CFR 50.55a) in 1996
IWL replaced use of the Regulatory Guides
Transition period was allowed for plants using regulatory guides
Applicable to ALL concrete containments

16. Current Regulatory Requirements
10 CFR 50.55a
Incorporates ASME B&PV Code Section XI by reference with conditions
References ASME Section XI Sub-Section IWE for Class MC containments and Liners of Class CC containments
References ASME Section XI Sub-Section IWL for Class CC containments
10 CFR 50.55a Currently endorses through the 2004 Edition
Rulemaking in progress to include the 2008 Addenda
Class will Reference the 2004 Edition

17. Containment Leak Testing
10 CFR 50 – Appendix J
Periodic testing of containment vessel and penetrations
Type A tests – Integrated Leak Rate Test
Type B and C tests – Local Leak Rate Tests

18. IWE Examinations IWE-1100 SCOPE
This Subsection provides requirements for inservice inspection of Class MC pressure retaining components and their integral attachments, and of metallic shell and penetration liners of Class CC pressure retaining components and their integral attachments in light-water cooled plants.

19. IWE Examinations Exempted Components
Components outside the boundaries of the containment system
Embedded or inaccessible portions of containment (with limitations on what modifications to plant can embed)
Piping, pumps, and valves (examined per either IWB or IWC)

20. IWE Examinations General Schedule for Inservice
10 year inspection interval
Divided into 3 inspection periods (3 or 4 years)
Provisions for shifting interval (and one of the periods) by one year
Preservice (in general)
Exam conducted prior to placing component inservice
Includes repair or replacement
Same exam as required for periodic inservice exam

21. IWE Examination Tables
Table from ASME B&PV Code Section XI Sub Section IWE -

22. IWE Examination Tables
Table from ASME B&PV Code Section XI Sub Section IWE -

23. IWE Details Category E-A Containment Surfaces
E1.11 – Accessible Surfaces
General Visual Each Period.
Includes Bolted Connections – VT-3 per 10 CFR 50.55a
E1.12 – Wetted Surfaces of Submerged Areas
General Visual Each Interval
VT-3 per 10 CFR 50.55a
E1.20 – BWR Vent System (Mark I)
E1.30 – Moisture Barriers
General Visual Each Period
Accessible is defined as visible by direct line of sight from permanent vantage points
Bolted connections do not have to be disassembled for inspection, but must be inspected in a disassemble state if disassembled.
Discuss experience with each type of examination.
Bolted connections added back as separate category in later code editions

24. IWE Details – Moisture Barriers

25. IWE Details Category E-C Augmented Examination
Applicable to areas subject to accelerated degradation or with previously noted degradation
E4.11 – Visible Surfaces
Detailed Visual Each Period.
VT-1 per 10 CFR 50.55a
E4.12 – Surface Area Grid
Ultrasonic Thickness Measurement (UT) Each Period
See IWE-1241 for details on augmented areas
Basically areas subjected to accelerated corrosion due to standing water or repeated wetting and drying (etc)

26. IWL Examinations IWL-1100 SCOPE
This Subsection provides requirements for preservice examination, inservice inspection, and repair/replacement activities of reinforced concrete and the post-tensioning systems of Class CC components, herein referred to as concrete containments as defined in CC-1000 {Section III Design Code}.

27. IWL Examinations Exempted Components
Steel portions not backed by concrete
Shell metallic liners
Penetration liners
Inaccessible tendon end anchorages (with limitations)
Concrete surfaces covered by the liner, foundation material, or backfill or otherwise obstructed. (Aging concerns for buried concrete addressed in later editions of code.)

28. IWL Examinations General Schedule for Inservice Examination Preservice
1, 3, and 5 years following Structural Integrity Test (SIT)
Within 6 months on either side of anniversary
Total inspection window of 1 year
10 years after SIT and every 5 years thereafter
Within 1 year on either side of anniversary
Total inspection window of 2 years
1 year plus or minus 3 months for concrete repairs
Preservice
Similar to IWE
Unique role of RPE

29. IWL Examinations Two Major Divisions Category L-A – Concrete Surfaces
All concrete containments
Category L-B – Unbonded Post-Tensioning System
Post tension design only
Tendons divided by type
Separate population for tendons impacted by repairs
Provisions for sites with multiple plants / units

30. IWL Examination Tables

31. IWL Details Category L-A Concrete Surfaces
L1.11 – All Accessible Areas
General Visual Each Inspection to identify suspect areas
Resolution per RPE
L1.12 – Suspect Areas
Detailed Visual
Up close exam to determine if the area is a problem
Performed by or under the direction of a Registered Professional Engineer
Accessible is defined as visible by direct line of sight from permanent vantage points

32. IWL Details Category L-B Unbonded Post-Tensioning Systems Sample Size
Sample of Tendons
4 % of Each Type
Minimum of 4 and Maximum of 10
Reduced sample for good inspection history
2 % of Each Type
Minimum of 3 and Maximum of 5
Separate population with reduced sample size for tendons affected by repair
Tendon type by construction – Horizontal (hoop), Vertical, Dome

33. Overview of Post-Tension Containment

34. Parts of a Tendon Anchorage

35. Exposed Tendon Anchorage

36. Uninstalled Tendon

37. Parts of a Tendon Anchorage

38. IWL Details L2.10 – Tendon Tendon Force / Elongation Test
Hydraulic Ram connected to end of tendon
Load cell measures force needed to lift tendon off of the shims
Common Tendon
One tendon is measured in each inspection
Results trended to ensure tendon stress remains above the minimum needed by design for life of the plant
Tendon type by construction – Horizontal (hoop), Vertical, Dome

39. IWL Details L2.20 – Wire or Strand
Destructive sample of one wire (typical tendon up to 186 wires) from one tendon of each type – NOT the common tendon
Visual exam for entire length
Sample from each end, the middle and area of most severe degradation tested for
Yield Strength,
Ultimate Strength, and
Elongation
Tendon type by construction – Horizontal (hoop), Vertical, Dome

40. IWL Details L2.30 – Anchorage Hardware and Surrounding Concrete
Detailed Visual – Entire Sample Population
Includes:
bearing plates,
anchor heads,
wedges,
buttonheads,
shims, and
concrete extending 2 feet from edge of the bearing plate.

41. IWL Details L2.40 – Corrosion Protection Medium L2.50 – Free Water
Sample from each end of each examined tendon
Chemical analysis for:
Water content,
Water soluble chlorides, nitrates, and sulfides
Reserve Alkalinity (expressed as milligrams of Potassium Hydroxide)
L2.50 – Free Water
The amount of any free water (if any) contained in the tendon cap is documented and analyzed to determine pH.
Water content per ASTM D 95 10% max
Chlorides per ASTM D 512 or D ppm
Nitrates per ASTM D 992, D 3867, or D ppm
Sulfides per APHA ppm
Reserve Alkalinity per ASTM D 974 Base Number 50% of the as-installed value with some expections. Always no less than zero.
TBN = [20 (N acid) – B (N base)]*56/W where
N acid is normality of sulfuric acid solution
N base is normality of sodium hydroxide solution
B is milliliters of sodium hydroxide
And W is weight of sample in grams
Sample is prepared with 20 cc of sulfuric acid and titrated with sodium hydroxide.

42. IWL Examinations Additional 10 CFR 50.55a exam:
Grease caps that are accessible must be visually examined to detect grease leakage or grease cap deformations.
Grease caps must be removed for this examination when there is evidence of grease cap deformation that indicates deterioration of anchorage hardware

43. Additional 10 CFR 50.55a Requirements
The licensee shall evaluate the acceptability of inaccessible areas when conditions exist in accessible areas that could indicate the presence of or result in degradation to such inaccessible areas.
Reporting Requirements
Other provisions
Other provisions include personnel qualification requirements, minimum illumination / max distance requirements etc.

44. Objectives
State the purpose of containment vessel as used at commercial nuclear power plants in the US
Describe the general types of containment vessels currently used in the US commercial nuclear power industry.
State the difference between Class MC and Class CC components.
State the regulations requiring inservice inspection of nuclear containment buildings.

45. Enabling Objectives (cont)
Be able to state the section of ASME Code providing requirements for inservice inspection of Class CC components of nuclear containment vessels.
Discuss the type and frequency of inservice examinations for nuclear power plant containment vessels.

46. References
10 CFR 50.55a
ASME B&PV Code Section XI, Subsections IWE and IWL, 2004 Edition
Rao, K. R. (editor), Companion Guide to the ASME Boiler and Pressure Vessel Code, 3rd Edition
EPRI TM-102C

47. Questions ?