The NRC issues regulatory guides to describe and make available to the public methods that the NRC staff considers acceptable 

for use in implementing specific parts of the agency=s regulations, techniques that the staff uses in evaluating specific problems or 

postulated accidents, and data that the staff needs in reviewing applications for permits and licenses. Regulatory guides are not 

substitutes for regulations, and compliance with them is not required. Methods and solutions that differ from those set forth in 

regulatory guides will be deemed acceptable if they provide a basis for the findings required for the issuance or continuance of a 

permit or license by the Commission. 

This guide was issued after consideration of comments received from the public. 

Regulatory guides are issued in 10 broad divisionsC1, Power Reactors; 2, Research and Test Reactors; 3, Fuels and Materials 

Facilities; 4, Environmental and Siting; 5, Materials and Plant Protection; 6, Products; 7, Transportation; 8, Occupational Health; 

9, Antitrust and Financial Review; and 10, General. 

Electronic copies of this guide and other recently issued guides are available through the NRC=s public Web site under the 

Regulatory Guides document collection of the NRC=s Electronic Reading Room at 

http://www.nrc.gov/reading-rm/doc-collections/ and through the NRC=s Agencywide Documents Access and Management 

System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html, under Accession No. ML101800540. The regulatory analysis 

may be found in ADAMS under Accession No. ML100560131. 

U.S. NUCLEAR REGULATORY COMMISSION October 2010

 Revision 3 

REGULATORY GUIDE 

OFFICE OF NUCLEAR REGULATORY RESEARCH 

REGULATORY GUIDE 1.193

(Draft was Issued as DG-1193, dated June 2009)

ASME CODE CASES NOT APPROVED FOR USE

A. INTRODUCTION

In Title 10, Part 50, of the Code of Federal Regulations (10 CFR Part 50), ADomestic Licensing of 

Production and Utilization Facilities@ (Ref. 1), Section 50.55a(c), AReactor Coolant Pressure Boundary,@

requires, in part, that components of the reactor coolant pressure boundary be designed, fabricated, erected, 

and tested in accordance with the requirements for Class 1 components of Section III, ARules for 

Construction of Nuclear Power Plant Components,@ of the American Society of Mechanical Engineers 

(ASME) Boiler and Pressure Vessel (BPV) Code (Ref. 2) or equivalent quality standards. The regulations 

at 10 CFR 50.55a(f), AInservice Testing Requirements,@ require, in part, that Class 1, 2, and 3 components 

and their supports meet the requirements of the ASME Code for Operation and Maintenance of Nuclear 

Power Plants (OM Code) (Ref. 3) or equivalent quality standards. Finally, 10 CFR 50.55a(g), 

AInservice Inspection Requirements,@ requires, in part, that Class 1, 2, 3, MC (metal containment), and CC 

(concrete containment) components and their supports meet the requirements of Section XI, ARules for 

Inservice Inspection of Nuclear Power Plant Components,@ of the ASME BPV Code or equivalent quality 

standards. 

The ASME publishes a new edition of the BPV and OM Codes every 3 years and new addenda 

every year. The latest editions and addenda of Section III, Section XI, and the OM Code that the U.S. 

Nuclear Regulatory Commission (NRC) has approved for use by licensees are referenced in 

10 CFR 50.55a(b). The ASME also publishes Code Cases for Section III and Section XI quarterly and 

Code Cases for the OM Code yearly. Code Cases provide alternatives developed and approved by the 

ASME. 
Rev. 3 of RG 1.193, Page 2 

With regard to the revision of this guide, the NRC staff reviewed Section III and Section XI Code 

Cases listed in Supplements 2B11 to the 2004 Edition, and Supplement 0 to the 2007 Edition of the ASME 

BPV Code. It should be noted that Supplement 0 to the 2007 Edition also serves as Supplement 12 to the 

2004 Edition. Revision 35 of Regulatory Guide 1.84, ADesign, Fabrication, and Materials Code Case 

Acceptability, ASME Section III@ (Ref. 4), and Revision 16 of Regulatory Guide 1.147, AInservice 

Inspection Code Case Acceptability, ASME Section XI, Division 1@ (Ref. 5), have been published 

concurrently with this guide to identify the Code Cases that the NRC has determined to be acceptable 

alternatives to applicable parts of Section III and Section XI. This regulatory guide does not approve the 

use of the Code Cases listed herein.

Because this regulatory guide does not approve the use of the Code Cases listed herein, it does not 

contain new or amended information collection requirements subject to the Paperwork Reduction Act 

of 1995 (Ref. 6). The NRC may neither conduct nor sponsor, and a person is not required to respond to, 

an information collection request or requirement unless the requesting document displays a currently valid 

control number issued by the Office of Management and Budget (OMB). 

B. DISCUSSION 

This regulatory guide lists the Code Cases that the NRC has determined not to be acceptable 

for use on a generic basis. A brief description of the basis for the determination is provided with each 

Code Case. Licensees may submit a request to implement one or more of the Code Cases listed below 

through 10 CFR 50.55a(a)(3), which permits the use of alternatives to the Code requirements referenced 

in 10 CFR 50.55a, provided that the proposed alternatives result in an acceptable level of quality 

and safety. Licensees must submit a plant-specific request that addresses the NRC=s concerns about 

the Code Case at issue. 

C. REGULATORY POSITION

For this guide, the NRC reviewed the Section III and Section XI Code Cases listed in Supplements 

2B11 to the 2004 Edition, and Supplement 0 to the 2007 Edition of the ASME BPV Code. Licensees may 

not implement Code Cases listed in this guide without prior NRC approval. 

1. Unacceptable Section III Code Cases

The NRC determined that the following Section III Code Cases are unacceptable for use 

by licensees in their Section III design and construction programs. 
Rev. 3 of RG 1.193, Page 3 

Table 1. Unacceptable Section III Code Cases

CODE 

CASE 

NUMBER 

TABLE 1 

UNACCEPTABLE SECTION III CODE CASES 

DATE 

SUMMARY 

N-284-1 Metal Containment Shell Buckling Design Methods, Section III, Division 1, 

Class MC

5/9/03 

 (1) The following errata, misprints, recommendations, and errors have 

been identified: 

 Fig. 1511.1, The curve for αθL should not exceed 0.8 for any value 

of (R/t). 

 -1512, The statement ASee Fig. 1512-1 then see -1713.1.2 

for method of calculating M@ should be rephrased as: ASee 

-1713.1.2 for method of calculating M, then see Fig. -1512-1.@

 -1513, Recommend AUse the value of αil given for spherical shells 

in accordance with -1512.@

 -1521, (i) In (a) Axial Compression, AαθG = αθL@ should be changed 

to AαφG = αφL.@ (ii) The source of the equations shown under A(a) 

Axial Compression@ provided separate instability equations for 

stringer-stiffened and ring-stiffened cylindrical shells. The Code 

Case adopted the instability equations pertaining to ring-stiffened 

shells, which are less conservative than those for stringer 

instability, for both ring and/or stringer stiffened cylindrical shells. 

 Is this the intent? (Ref. 7). 

 -1712.1.1, The equation ACθh = 0.92/(Mθ - 0.636)@ should be 

changed to ACθh = 0.92/(Mφ - 0.636).@

 -1712.1.1-1, The leftmost curve should be labeled Cθh. 

 -1712.2.2, (a) Axial Compression, (i) In the formula for σφej, the 

denominator should be (mπ/Lj)

2 C tφ. (ii) The expressions for Cφ

and Cθ should be separated. 

 -1712.2.3, (i) The factor 1.944 in an older edition has been 

changed to 2.00. No basis is apparent. (ii) The misprint At 1

3@

should be corrected to At1

3.@

 -1713.1.1, (i) The equation Aστa=αφθCσφθel/FS@ should be changed 

to Aστa=αφθLCσφθel/FS.@ (ii) The title of (c) should be changed to 

AAxial Compression Plus In-Plane Shear.@

 -1713.1-1, In (b), the lower value AKs=σra@ on the vertical axis 

should be changed to AKs=σha.@

 -1713.2.1, (i) The headings for (b) and (c) should include the 

words AIn-Plane.@ (ii) In (b) AAxial Compression Plus Shear,@ Aσθ@

should be changed to Aσφ.@
Rev. 3 of RG 1.193, Page 4 

CODE 

CASE 

NUMBER 

TABLE 1 

UNACCEPTABLE SECTION III CODE CASES 

DATE 

SUMMARY 

N-284-1 

(cont’d) 

Metal Containment Shell Buckling Design Methods, Section III, Division 1, 

Class MC

5/9/03 

 (2) Applicants intending to use Code Case N-284-1 shall submit a request 

to the NRC staff for its review and approval on a plant-specific basis. 

(3) The rules applicable to evaluate the buckling and instability 

of containment shells for Section III, Division 3, are under 

development. Currently, use of Code Case N-284-1 by licensees for 

storage canisters and transportation casks is permissible provided it has 

been reviewed and approved by the NRC 

N-483-2 

N-483-3 

Alternative Rules to the Provisions of NCA-3800, Requirements for 

Purchase of Material, Section III, Divisions 1 and 3

5/7/99 

2/25/02 

 The Code Case lacks sufficient detail to ensure that the supplied material is 

as represented by the Certified Material Test Report. 

N-510 

N-510-1 

Borated Stainless Steel for Class CS Core Support Structures and Class 1 

Component Supports, Section III, Division 1

12/9/93 

8/14/01 

 No technical basis was provided for expanding the Code Case to include 

borated stainless steel Types 304B, 304B1, 304B2, and 304B3. A 

considerable amount of information was required to support the types 

presently contained in the Code Case. The revised Code Case would permit 

borated stainless steel to be used for component supports within the reactor 

vessel. The technical basis to support the Code Case only addresses the use 

of these materials as component supports in spent fuel racks and 

transportation casks. 

N-519 Use of 6061-T6 and 6061-T651 Aluminum for Class 1 Nuclear Components Annulled 2/3/03 

 Code Case is applicable to only one DOE aluminum vessel. 

N-530 Provisions for Establishing Allowable Axial Compressive Membrane 

Stresses in the Cylindrical Walls of 0-15 Psi Storage Tanks, Classes 2 and 3

2/3/03 

 There are numerous errors in the equations. The errors must be corrected 

before the Code Case can be approved for use. 
Rev. 3 of RG 1.193, Page 5 

CODE 

CASE 

NUMBER 

TABLE 1 

UNACCEPTABLE SECTION III CODE CASES 

DATE 

SUMMARY 

N-565 Alternative Methods of Nozzle Attachment for Class 1 Vessels 12/3/99 

 The Code Case essentially requires a design using a seal to protect the 

threads from the contained fluid, and seals are not a Code item. The seal, 

which plays a very important part in the integrity of the joint, imposes too 

great a vulnerability in the design. The supporting information for the Code 

Case does not demonstrate the resulting threaded nozzle configuration is 

equivalent in integrity to that of a welded connection. 

N-595 

N-595-1 

N-595-2 

N-595-3 

N-595-4 

Requirements for Spent Fuel Storage Canisters, Section III, Division 1 2/26/99 

9/24/99 

12/8/00 

04/08/02 

05/12/04 

Regulatory approval for the use of multi-purpose casks is presently 

addressed by the NRC Spent Fuel Project Office Interim Staff Guidance No. 

4 (ISG-4), Rev. 1 (Ref. 8), and Interim Staff Guidance No. 18 (ISG-18), 

Rev. 1 (Ref. 13). The interim staff guidance provides a framework to ensure 

that the cask system, as designed, and when fabricated and used in 

accordance with the conditions specified in its Certificate of Compliance, 

meets the requirements of 10 CFR Part 72, ALicensing Requirements for the 

Independent Storage of Spent Nuclear Fuel, High-Level Radioactive Waste, 

and Reactor-Related Greater than Class C Waste@ (Ref. 9). It should be 

noted that Code Case N-717 replaces Code Case N-595-X. 

N-645 

N-645-1 

Use of Rupture Disk Devices on Nuclear Fuel Storage Canisters, Class 1, 

Section III, Division 1

6/14/00 

2/3/03 

 The NRC does not permit the use of rupture disk devices in spent nuclear 

fuel storage canister designs. 
Rev. 3 of RG 1.193, Page 6 

CODE 

CASE 

NUMBER 

TABLE 1 

UNACCEPTABLE SECTION III CODE CASES 

DATE 

SUMMARY 

N-659 

N-659-1 

Use of Ultrasonic Examination in Lieu of Radiography for Weld 

Examination, Section III, Division 1

9/17/02 

11/18/03 

 The NRC is not going to endorse Code Case N-659 or Code Case N-659-1 at 

this time given the number of issues raised by NRC staff and the concerns 

expressed in the public comments. The NRC has determined that a more 

effective approach for developing a suitable performance demonstration 

program would be to work with ASME International to resolve the issues. 

Code Case N-659 was conditionally approved in Draft Regulatory Guide 

DG-1133 (proposed Revision 34 of Regulatory Guide 1.84), which was 

published for public comment on October 27, 2006 (71 FR 62947). 

Additional draft conditions were discussed in the statement of considerations 

for the proposed rule. Code Case N-659-1 was listed as unapproved in Draft 

Regulatory Guide DG-1135 (proposed Revision 2 to Regulatory Guide 

1.193, AASME Code Cases Not Approved for Use@), which was 

N-670 Use of Ductile Cast Iron Conforming to ASTM A 874/ A 874M-98 or JIS 

G5504-1992 for Transport Containments, Section III, Division 3

7/01/05 

 The NRC has not yet endorsed Section III, Division 3, “Containments for 

Transportation and Storage of Spent Nuclear Fuel and High Level 

Radioactive Material and Waste.” Thus, it would not be appropriate to 

approve a Code Case that is an alternative to the Section III, Division 3, 

provisions. 

N-673 Boron Containing Power Metallurgy Aluminum Alloy for Storage and 

Transportation of Spent Nuclear Fuel, Section III, Division 1 

8/7/03 

 The Code Case does not address the following: 

(1) Corrosion properties of this material in spent fuel pool 

chemistry and/or clean water. 

(2) Impact properties for use as a structural material. 

(3) Uniform distribution of boron carbide in the aluminum matrix. 

(4) Mechanical properties for the use of the material in hightemperature conditions.
Rev. 3 of RG 1.193, Page 7 

CODE 

CASE 

NUMBER 

TABLE 1 

UNACCEPTABLE SECTION III CODE CASES 

DATE 

SUMMARY 

N-693 Alternative Method to the Requirements of NB-3228.6 for Analyzing Piping 

Subjected to Reversing Dynamic Load, Section III, Division 1

5/21/03 

 The Code Case would permit the use of the design, service, and test limits in 

Paragraph NB-3656(b) for Level D Service Limits. The limits in Paragraph 

NB-3656(b) are prohibited per 10 CFR 50.55a(b)(1)(iii). 

N-707 Use of SA-537, Class 1 Plate Material for Spent-Fuel Containment Internals 

in Non-pressure Retaining Applications Above 700°F (370°C), Section III, 

Division 3

11/12/04 

 The NRC has not yet endorsed Section III, Division 3, “Containments for 

Transportation and Storage of Spent Nuclear Fuel and High Level 

Radioactive Material and Waste.” Thus, it would not be appropriate to 

approve a Code Case that is an alternative to the Section III, Division 3, 

provisions. 

N-717 Requirements for Construction of Storage Containments for Spent Nuclear 

Fuel and High Level Radioactive Waste and Material, Section III, 

Division 3 

5/04/04 

 The NRC has not yet endorsed Section III, Division 3, “Containments for 

Transportation and Storage of Spent Nuclear Fuel and High Level 

Radioactive Material and Waste.” Thus, it would not be appropriate to 

approve a Code Case that is an alternative to the Section III, Division 3, 

provisions. 

The provisions of the Code Case are copied from the July 1, 2005, addenda 

to Section III, Division 3. The changes to the ASME Code contained in the 

addenda are scheduled to be reviewed by the NRC staff in FY 2009. 

The Code Case is listed in this guide pending the results of the NRC staff 

review. 

N-728 Use of ASTM B 932-04 Plate Material for Nonpressure Retaining Spent 

Fuel Containment Internals to 650°F (343°C), Section III, Division 3

10/11/05 

 The NRC has not yet endorsed Section III, Division 3, “Containments for 

Transportation and Storage of Spent Nuclear Fuel and High Level 

Radioactive Material and Waste.” Thus, it would not be appropriate to 

approve a Code Case that is an alternative to the Section III, Division 3, 

provisions. 
Rev. 3 of RG 1.193, Page 8 

2. Unacceptable Section XI Code Cases

The NRC determined that the following Section XI Code Cases are unacceptable for use 

by licensees in their Section XI inservice inspection programs. 

Table 2. Unacceptable Section XI Code Cases 

Code Case 

Number 

Table 2 

Unacceptable Section XI Code Cases 

Date 

 Summary 

N-465 

N-465-1 

Alternative Rules for Pump Testing, Section XI, Division 1 11/30/88 

Annulled 

2/14/03 

The draft standard referenced in the Code Case is outdated. The requirements 

contained in the OM Code, ACode for Operation and Maintenance of Nuclear 

Power Plants,@ should be used. Note that Revision 12 of Regulatory Guide 

1.147 (Ref. 5) approved N-465 for use. The disapproval of N-465 for use 

applies only to new users. 

N-473 

N-473-1 

Alternative Rules for Valve Testing, Section XI, Division 1 3/8/89 

Annulled 

2/14/03 

 The draft standard referenced in the Code Case is outdated. The requirements 

contained in the OM Code, ACode for Operation and Maintenance of Nuclear 

Power Plants,@ should be used. Note that Revision 12 of Regulatory Guide 

1.147 (Ref. 5) approved N-473 for use. The disapproval of N-473 for use 

applies only to new users. 

N-480 Examination Requirements for Pipe Wall Thinning Due to Single Phase 

Erosion and Corrosion, Section XI, Division 1

Annulled 

9/18/01 

 Code Case has been superseded by Code Case N-597, ARequirements for 

Analytical Evaluation of Pipe Wall Thinning,@ implemented in conjunction 

with NSAC-202L, ARecommendations for an Effective Flow-Accelerated 

Corrosion Program@ (Ref. 10). 

N-498-2 

N-498-3 

Alternative Requirements for 10-Year System Hydrostatic Testing 

for Class 1, 2, and 3 Systems, Section XI, Division 1

6/9/95 

5/20/98 

 Code Case N-498-4 is conditionally approved in Revision 13 of Regulatory 

Guide 1.147 (Ref. 5). Those licensees choosing to implement this Code Case 

are to implement Revision 4, which is listed in Revision 15 of Regulatory 

Guide 1.147. 
Rev. 3 of RG 1.193, Page 9 

Code Case 

Number 

Table 2 

Unacceptable Section XI Code Cases 

Date 

 Summary 

N-532-2 Alternative Requirements to Repair and Replacement Documentation 

Requirements and Inservice Summary Report Preparation and Submission as 

Requested by IWA-4000 and IWA-6000, Section XI, Division 1

7/23/02 

 The following concerns were identified during review of the Code Case: 

(1) The Code Case references new paragraph IWA-6350, which has not yet 

been incorporated into the ASME Code. 

(2) NRC staff had difficulty reconciling Footnote 1 and Table 4 regarding the 

applicable edition and addenda. 

(3) Submission of Form OAR-1 is at the end of each inspection period, 

 rather than 90 days following the outage. 

N-542 Alternative Requirements for Nozzle Inside Radius Section Length Sizing 

Performance Demonstration, Section XI, Division 1

Annulled 

3/28/01 

 Code Case N-542 was subsumed by Code Case N-552, 

AAlternative MethodsBQualification for Nozzle Inside Radius Section from the 

Outside Surface,@ which is being implemented by licensees. Thus, there is no 

need to approve Code Case N-542.

N-547 Alternative Examination Requirements for Pressure Retaining Bolting of 

Control Rod Drive (CRD) Housings, Section XI, Division 1

Annulled 

5/20/01 

 Code Case NB547 states that the examination of CRD housing bolts, studs, and 

nuts is not required. However, 10 CFR 50.55a(b)(2)(xxi)(B) requires the 

examination of CRD bolting material whenever the CRD housing is 

disassembled and the bolting material is to be reused. Examination of CRD 

bolting material is required to verify that service-related degradation has not 

occurred, or that damage such as bending and galling of threads has not 

occurred when performing maintenance activities that require the removal and 

reinstallation of bolting.
Rev. 3 of RG 1.193, Page 10 

Code Case 

Number 

Table 2 

Unacceptable Section XI Code Cases 

Date 

 Summary 

N-560 

N-560-1 

N-560-2 

Alternative Examination Requirements for Class 1, Category B-J Piping 

Welds, Section XI, Division 1

8/9/96 

2/26/99 

2/14/03

 (1) The Code Case does not address inspection strategy for existing 

augmented and other inspection programs such as intergranular stress 

corrosion cracking (IGSCC), flow-assisted corrosion (FAC), 

microbiological corrosion (MIC), and pitting. 

(2) The Code Case does not provide system-level guidelines for change in 

risk evaluation to ensure that the risk from individual system failures will 

be kept small and dominant risk contributors will not be created. 

N-561 

N-561-1 

Alternative Requirements for Wall Thickness Restoration of Class 2 and High 

Energy Class 3 Carbon Steel Piping, Section XI, Division 1

12/31/96 

3/28/01

 Neither the ASME Code nor the Code Case have criteria for determining the 

rate or extent of degradation of the repair or the surrounding base metal. 

Reinspection requirements are not provided to verify structural integrity since 

the root cause may not be mitigated.

N-562 

N-562-1 

Alternative Requirements for Wall Thickness Restoration of Class 3 Moderate 

Energy Carbon Steel Piping, Section XI, Division 1

12/31/96 

3/28/01

 Neither the ASME Code nor the Code Case have criteria for determining the 

rate or extent of degradation of the repair or the surrounding base metal. 

Reinspection requirements are not provided to verify structural integrity since 

the root cause may not be mitigated.

N-574 NDE Personnel Recertification Frequency, Section XI, Division 1 Annulled 

7/14/06 

 Based on data obtained by the NRC staff during its review of Appendix VIII, 

APerformance Demonstration for Ultrasonic Examination Systems,@ to Section 

XI, the NRC staff noted that proficiency decreases over time. The data do not 

support recertification examinations at a frequency of every 5 years.

N-575 Alternative Examination Requirements for Full Penetration 

Nozzle-to-Vessel Welds in Reactor Vessels with Set-On Type Nozzles, 

Section XI, Division 1

2/14/03 

 The supporting basis for the Code Case applies to the specific configuration of 

one plant and is not applicable on a generic basis. In addition, there are 

insufficient controls on stress and operating conditions to permit a generic 

reduction in examination volume. Finally, the boundaries of the volume of the 

weld, cladding, and heat affected zone from Figure 2 are ambiguous.
Rev. 3 of RG 1.193, Page 11 

Code Case 

Number 

Table 2 

Unacceptable Section XI Code Cases 

Date 

 Summary 

N-577 

N-577-1 

Risk-Informed Requirements for Class 1, 2, and 3 Piping, Method A, 

Section XI, Division 1

9/2/97 

2/14/03

(1) The Code Case does not address inspection strategy for existing 

augmented and other inspection programs such as IGSCC, FAC, MIC, 

and pitting. 

(2) The Code Case does not provide system-level guidelines for change in 

risk evaluation to ensure that the risk from individual system failures will 

be kept small and dominant risk contributors will not be created. 

N-578 

N-578-1 

Risk-Informed Requirements for Class 1, 2, and 3 Piping, Method B, 

Section XI, Division 1

9/2/97 

2/14/03

(1) The Code Case does not address inspection strategy for existing 

augmented and other inspection programs such as IGSCC, FAC, MIC, 

and pitting. 

(2) The Code Case does not provide system-level guidelines for change in 

risk evaluation to ensure that the risk from individual system failures will 

be kept small and dominant risk contributors will not be created. 

N-587 Alternative NDE Requirements for Repair/Replacement Activities, 

Section XI, Division 1

Annulled 

2/14/03

 The NRC believes this Code Case is in conflict with the review process for 

approval of alternatives under 10 CFR 50.55a(a)(3). The Code Case would 

permit a licensee and the Authorized Nuclear Inspector to choose unspecified 

alternatives to regulatory requirements.

N-589 

N-589-1 

Class 3 Nonmetallic Cured-in-Place Piping, Section XI, Division 1 4/19/02 

7/23/02

(1) The installation process provides insufficient controls on wall thickness 

measurement. 

(2) There are no qualification requirements for installers and installation 

procedures such as those for welders and welding procedures. 

(3) Fracture toughness properties of the fiberglass are such that the cured-inplace piping (CIPP) could crack during a seismic event. 

(4) Equations 4 and 5 in the Code Case contain an Ai@ term [a stress 

intensification factor] that is derived from fatigue considerations. Stress 

intensification factors, however, have not been developed for fiberglass 

materials. 
Rev. 3 of RG 1.193, Page 12 

Code Case 

Number 

Table 2 

Unacceptable Section XI Code Cases 

Date 

 Summary 

N-590 Alternative to the Requirements of Subsection IWE, Requirements for 

Class MC and Metallic Liners of Class CC Components of Light-Water 

Cooled Plants, Section XI, Division 1

Annulled 

4/08/02

 The provisions of the Code Case were incorporated into the 1998 Edition, 

which has been approved by the NRC. Thus, the Code Case is no longer 

needed and was annulled by the ASME. 

N-591 Alternative to the Requirements of Subsection IWL, Requirements for 

Class CC Concrete Components of Light-Water Cooled Plants, Section XI, 

Division 1

Annulled 

4/08/02

 The provisions of the Code Case were incorporated into the 1998 Edition 

which has been approved by the NRC. Thus, the Code Case is no longer 

needed and was annulled by the ASME. 

N-593-1 Examination Requirements for Steam Generator Nozzle-to-Vessel Welds, 

Section XI, Division 1 

10/08/04 

 The Code Case eliminates the requirement to examine the steam generator 

nozzle inner radius. Specifically, the examination volume for the nozzle inner 

radius was removed from Section XI, Figures IWB-2500-7(a) through IWB2500-7(d). The action is applicable from the 1974 Edition through the 2004 

Edition with the 2005 Addenda. A similar action was taken regarding Code 

Case N-619. The NRC did not taken exception to Code Case N-619 because 

10 CFR 50.55a(b)(2)(xxi)(A) requires licensees to perform the examination in 

accordance with the 1998 Edition, which includes figures containing the 

examination volume. However, Code Case N-593-1 applies to editions prior 

to the 1998 Edition which do not have the appropriate figures. 

N-613 Ultrasonic Examination of Full Penetration Nozzles in Vessels, Examination 

Category B-D, Item No=s. B3.10 and B3.90, Reactor Vessel-To-Nozzle Welds, 

Fig. IWB-2500-7(a), (b), and (c), Section XI, Division 1

7/30/98

 The Code Case conflicts with and unacceptably reduces the requirements of 

10 CFR 50.55a(b)(2)(xv)(K)(2)(i). A revision to the Code Case has been 

developed to address the concerns. 

N-615 Ultrasonic Examination as a Surface Examination Method for Category B-F 

and B-J Piping Welds, Section XI, Division 1

7/28/01 

 The Code Case requires that the ultrasonic technique used be demonstrated 

capable of detecting certain size flaws on the outside diameter of the weld, but 

it does not specify any demonstration requirements. To be acceptable, Section 

XI, Appendix VIII, type rules for performance demonstration need to be 

developed and applied. 
Rev. 3 of RG 1.193, Page 13 

Code Case 

Number 

Table 2 

Unacceptable Section XI Code Cases 

Date 

 Summary 

N-618 Use of a Reactor Pressure Vessel as a Transportation Containment System, 

Section XI, Division 1

6/17/03

 The Code Case was developed as a potential option for shipping and disposal 

of a reactor pressure vessel (RPV). The NRC staff determined, however, that 

the Code Case was not applicable to the review and approval process for 

transportation packages. The use of RPVs as a transportation package has 

been addressed under 10 CFR Part 71, APackaging and Transportation of 

Radioactive Material@ (Ref. 11). 

N-622 Ultrasonic Examination of RPV and Piping, Bolts, and Studs, Section XI, 

Division 1

Annulled on 

1/12/05

 The Code Case was published in May 1999. Industry Performance 

Demonstration Initiative efforts since that time have made this Code Case 

obsolete. Issues associated with supplements to Appendix VIII are being 

addressed individually in separate Code Cases. 

N-653 Qualification Requirements for Full Structural Overlaid Wrought Austenitic 

Piping Welds, Section XI, Division 1

9/7/01 

 (1) Section XI, Appendix VIII, Supplement 11, requires a personnel 

performance qualification as part of the procedure qualification. The 

detection acceptance criteria in the Code Case do not require personnel 

performance qualification as part of the procedure qualification. 

Personnel qualification is necessary to validate the effectiveness of the 

procedure qualification. 

(2) The minimum grading unit is 1.0 inch in the circumferential direction. 

The acceptance tolerance, however, is 0.75 inch root mean square error. 

Thus, the length sizing acceptance criteria do not adequately prevent the 

use of testmanship rather than skill to pass length sizing tests. 

N-654 Acceptance Criteria for Flaws in Ferritic Steel Components 4 in. and Greater 

in Thickness, Section XI, Division 1

4/17/02

 Licensees intending to apply the rules of this Code Case must obtain 

NRC approval of the specific application in accordance with 

10 CFR 50.55a(a)(3). 
Rev. 3 of RG 1.193, Page 14 

Code Case 

Number 

Table 2 

Unacceptable Section XI Code Cases 

Date 

 Summary 

N-691 Application of Risk-Informed Insights to Increase the Inspection Interval for 

Pressurized Water Reactor Vessels, Section XI, Division 1

11/18/03

A response to the NRC staff=s request for additional information has not yet 

been received and therefore, insufficient information has been provided for the 

staff to make a determination relative to the acceptability of this Code Case. 

N-702 Alternative Requirements for Boiling Water Reactor (BWR) Nozzle Inner 

Radius and Nozzle-to-Shell Welds, Section XI, Division 1 

2/20/04 

The applicability of Code Case N-702 must be shown by demonstrating that 

the criteria in Section 5.0 of NRC Safety Evaluation dated December 18, 2007 

(ML073600374) regarding BWRVIP-108: “BWR Vessel and Internals 

Project, Technical Basis for the Reduction of Inspection Requirements for the 

Boiling Water Reactor Nozzle-to-Vessel Shell Welds and Nozzle Blend 

Radii,” EPRI Technical Report 1003557, October 2002 (ML-023330203) are 

met. The evaluation demonstrating the applicability of the Code Case shall be 

reviewed and approved by the NRC prior to the application of the Code Case.

N-711 Alternative Examination Coverage Requirements for Examination Category 

B-F, B-J, C-F-1, C-F-2, and R-A Piping Welds, Section XI, Division 1 

1/05/06 

The Code Case would permit each licensee to independently determine when 

achievement of a coverage requirement is impractical, and when Coderequired coverage is satisfied. As a result, application of the Code Case for 

similar configurations at different plants could result in potentially significant 

quantitative variations. Furthermore, application of the Code Case is 

inconsistent with NRC’s responsibility for determining whether examinations 

are impractical, and eliminates the NRC’s ability to take exception to a 

licensee’s proposed action and impose additional measures where warranted in 

accordance with 10 CFR 50.55a(g)(6)(i). 

N-716 Alternative Piping Classification and Examination Requirements, Section XI, 

Division 1 

4/19/06 

The NRC has approved risk-informed inservice inspection programs based, in 

part, on methods described in Code Case N-716. The NRC has approved 

programs for Grand Gulf Nuclear Station 1 (September 21, 2007; 

ML072430005) , Donald C. Cook Nuclear Plant (September 28, 2007; 

ML072620553), and Waterford Steam Electric Station (April 28, 2008; 

ML080980120). The approvals were specific to these units and relied on 

several changes to the methodology described in Code Case N-716 and a 

determination by the NRC that the probabilistic risk analyses (PRA) were of 

sufficient technical adequacy. It is anticipated that changes will be made to the 

Code Case. The staff will consider the revised Code Case for generic approval 

when it is published by the ASME, and a generic definition of PRA technical 

adequacy is available. 
Rev. 3 of RG 1.193, Page 15 

Code Case 

Number 

Table 2 

Unacceptable Section XI Code Cases 

Date 

 Summary 

N-729 Alternative Examination Requirements for PWR Reactor Vessel Upper Heads 

With Nozzles Having Pressure-Retaining Partial-Penetration Nozzles, 

Section XI, Division 1

06/28/05 

Code Case N-729 has been superseded by Revision 1 to the Code Case. 

N-729-1 is conditionally approved directly in 10 CFR 50.55a and is approved 

in Regulatory Guide 1.147.

N-740 Dissimilar Metal Weld Overlay for Repair of Class 1, 2, and 3 Items, 

Section XI, Division 1 

10/12/06 

Revision 2 to the Code Case is currently under development by Section XI. 

Revision 1 has been published, but the NRC staff has many issues with 

Revisions 0 and 1. The issues have been communicated to the cognizant 

Section XI committees, and the staff continues to work with the committees to 

resolve the issues. Due to the total number of issues and the nature of some 

(e.g., lack of certain fundamental design details), the staff believes that it 

would be inappropriate to attempt to conditionally approve either version 0 or 

1 in Regulatory Guide 1.147. The staff will consider Revision 2 for approval 

when it is published by the ASME.

N-747 Reactor Vessel Head-to-Flange Weld Examinations, Section XI, Division 1 1/13/06 

Industry organizations submitted documentation which could be used to 

establish a conservative neutron fluence estimate and a conservative RTNDT

value for the subject welds during the public comment period for the proposed 

rule published on June 2, 2009 (74 FR 26303). It was determined that this 

Code Case could not be generically approved without providing the public an 

opportunity to comment. The documentation submitted to support transferring 

this Code Case from Regulatory Guide 1.193 to Regulatory Guide 1.147 will 

be discussed in the next proposed rule. 
Rev. 3 of RG 1.193, Page 16 

3. Unacceptable OM Code Cases

The following OM Code Cases were determined to be unacceptable for use by licensees in their 

inservice testing programs. The ASME issues OM Code Cases annually with publication of a new edition 

or addenda. No new OM Code Cases were added in this revision. To assist users of the OM Code, 

Column 3 of Table 3 lists the edition or addenda to which each Code Case was attached (E: edition; 

A: addenda), and whether the Code Case is new or reaffirmed. 

Table 3. Unacceptable OM Code Cases 

Code Case 

Number 

Table 3 

Unacceptable OM Code Cases 

Edition/ 

Addenda 

Summary of Basis for Exclusion 

OMN-10, Rev. 0 Requirements for Safety Significance Categorization of Snubbers Using Risk 

Insights and Testing Strategies for Inservice Testing of LWR Power Plants

July 1, 2000A 

The method used for categorizing snubbers could result in certain snubbers 

being inappropriately categorized as having low safety significance. These 

snubbers would not be adequately tested or inspected to provide assurance of 

their operational readiness. In addition, unexpected extensive degradation in 

feedwater piping has occurred which would necessitate a more rigorous 

approach to snubber categorization than presently contained in this Code 

Case. 

D. IMPLEMENTATION 

The purpose of this section is to provide information on how applicants and licensees1

 may use 

this guide and information regarding the NRC’s plans for using this Regulatory Guide. In addition, it 

describes how the NRC staff has complied with the Backfit Rule, 10 CFR 50.109 and any applicable 

finality provisions in 10 CFR Part 52. 

Applicant and Licensees’ Use 

Applicants and licensees may (i.e., voluntarily) use the information in this regulatory guide to 

develop applications for initial licenses, amendments to licenses, or other requests for NRC regulatory 

approval (e.g., exemptions). Licensees may use the information in this regulatory guide for actions which 

do not require prior NRC review and approval (e.g., changes to a facility design under 10 CFR 50.59 

which do not require prior NRC review and approval). Licensees may use the information in this 

Regulatory Guide or applicable parts to resolve regulatory or inspection issues (e.g., by committing to 

comply with provisions in the regulatory guide). 

Current licensees may continue to use the guidance that was found acceptable for complying with 

specific portions of the regulations as part of their license approval process, which may be a previous 

version of this Regulatory Guide. 

 

1 In this section, “licensees” include applicants for standard design certifications under 10 CFR Part 52. 
Rev. 3 of RG 1.193, Page 17 

A licensee who believes that the NRC staff is inappropriately imposing this Regulatory Guide as 

part of a request for a license amendment or request for a change to a previously issued NRC regulatory 

approval may file a backfitting appeal with the NRC in accordance with applicable procedures. 

NRC Staff Use 

The NRC staff does not intend or approve any imposition or backfitting of the guidance in this 

Regulatory Guide. The staff does not expect any existing licensee to use or commit to using the guidance 

in this Regulatory Guide in the absence of a licensee-initiated change to its licensing basis. The NRC staff 

does not expect or plan to request licensees to voluntarily adopt this Regulatory Guide to resolve a generic 

regulatory issue. The NRC staff does not expect or plan to initiate NRC regulatory action which would 

require the use of this regulatory guide (e.g. issuance of an order requiring the use of the Regulatory Guide, 

requests for information under 10 CFR 50.54(f) as to whether a licensee intends to commit to use of this 

regulatory guide, generic communication, or promulgation of a rule requiring the use of this Regulatory 

Guide) without further back-fit consideration. 

During inspections of specific facilities, the staff may suggest or recommend that licensees 

consider various actions consistent with staff positions in this regulatory guide. Such suggestions and 

recommendations would not ordinarily be considered backfitting even if prior versions of this Regulatory 

Guide are part of the licensing basis of the facility with respect to the subject matter of the inspection. 

However, the staff may not represent to the licensee that: (i) the licensee’s failure to comply with the 

positions in this Regulatory Guide constitutes a violation; (ii) the licensee may avoid the violation by 

agreeing to comply with this Regulatory Guide; or (iii) the only acceptable way for the licensee to address 

the NRC-identified non-compliance or violation is to commit to this Regulatory Guide (i.e., including this 

Regulatory Guide in the facility’s licensing basis). 

If an existing licensee seeks a license amendment or change to an existing regulatory approval, and 

the staff’s consideration of the request involves a regulatory issue which is directly relevant to this 

Regulatory Guide and the specific subject matter of the new or revised guidance is an essential 

consideration in the NRC staff’s determination of the acceptability of the licensee’s request, the staff may 

require the licensee to use this Regulatory Guide as a prerequisite for NRC approval. This is not 

considered backfitting as defined in 10 CFR 50.109(a)(1) or a violation of any of the issue finality 

provisions in 10 CFR Part 52. 

Conclusion 

 This regulatory guide is not being imposed upon current licensees and may be voluntarily used by 

existing licensees. In addition, this Regulatory Guide is issued in conformance with all applicable internal 

NRC policies and procedures governing backfitting. Accordingly, the NRC’s staff issuance of this 

regulatory guide is not considered backfitting, as defined in 10 CFR 50.109(a)(1), nor is it deemed to be in 

conflict with any of the issue finality provisions in 10 CFR Part 52.
Rev. 3 of RG 1.193, Page 18 

REFERENCES2

1. Code of Federal Regulations, Title 10, Energy, Part 50, ADomestic Licensing of Production and 

Utilization Facilities@ (10 CFR Part 50), U.S. Nuclear Regulatory Commission, Washington, DC. 

2. ASME Boiler and Pressure Vessel Code, Section III, ARules for Construction of Nuclear Power 

Plant Components,@ Division I; and Section XI, ARules for Inservice Inspection of Nuclear Power 

Plant Components,@ American Society of Mechanical Engineers, New York, NY.3

3. ASME Code for Operation and Maintenance of Nuclear Power Plants, American Society 

of Mechanical Engineers, New York, NY.2

4. Regulatory Guide 1.84, ADesign, Fabrication, and Materials Code Case Acceptability, 

ASME Section III,@ U.S. Nuclear Regulatory Commission, Washington, DC.4

5. Regulatory Guide 1.147, AInservice Inspection Code Case Acceptability, ASME Section XI, 

Division 1,@ U.S. Nuclear Regulatory Commission, Washington, DC. 

6. Paperwork Reduction Act of 1995 (Public Law 104-13), United States Code, Title 44, 

APublic Printing and Documents,@ Chapter 35, ACoordination of Federal Information Policy@

(44 U.S.C. 3501 et seq.), 104th Congress of the United States of America, Washington, DC.5

7. Miller, C.D., ASummary of Buckling Tests on Fabricated Steel Cylindrical Shells in USA,@

in Offshore Structures Engineering III: Buckling of Shells in Offshore Structures, J.E. Harding, 

P.J. Dowling, and N. Agelidis, eds., Gulf Publishing Company, Houston, TX, pp. 429B447, 1982. 

 

2

 Publicly available NRC published documents are available electronically through the Electronic Reading Room on the 

NRC’s public Web site at: http://www.nrc.gov/reading-rm/doc-collections/. The documents can also be viewed on-line 

or printed for a fee in the NRC’s Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD; the mailing 

address is USNRC PDR, Washington, DC 20555; telephone 301-415-4737 or (800) 397-4209; fax (301) 415-3548; 

and e-mail pdr.resource@nrc.gov. 

3

 Copies may be purchased from the American Society of Mechanical Engineers, Three Park Avenue, NewYork, NY 

10016-5990; phone (212) 591-8500; fax (212) 591-8501; www.asme.org. 

4

 All regulatory guides listed herein are available electronically through the Electronic Reading Room on the NRC=s 

public Web site at http://www.nrc.gov/reading-rm/doc-collections/reg-guides/. Active guides may be purchased from 

the National Technical Information Service (NTIS). Details may be obtained by contacting NTIS at 5285 Port Royal 

Road, Springfield, Virginia 22161, online at http://www.ntis.gov, by telephone at (800) 553-NTIS (6847) or (703) 605-

6000, or by fax to (703) 605-6900. Copies are also available for inspection or copying for a fee from the NRC=s Public 

Document Room (PDR), which is located at 11555 Rockville Pike, Rockville, Maryland; the PDR=s mailing address is 

USNRC PDR, Washington, DC 20555-0001. The PDR can also be reached by telephone at (301) 415-4737 

or (800) 397-4209, by fax at (301) 415-3548, and by email to PDR.Resource@nrc.gov. 

5

 The Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.) is available electronically through the Federal Register

Web site administered by the U.S. National Archives and Records Administration, at http://www.archives.gov/federalregister/laws/paperwork-reduction/
Rev. 3 of RG 1.193, Page 19 

8. NRC Spent Fuel Project Office Interim Staff Guidance No. 4 (ISG-4), Rev. 1, ACask Closure Weld 

Inspections,@ U.S. Nuclear Regulatory Commission, Washington, DC.6

9. Code of Federal Regulations, Title 10, Energy, Part 72, ALicensing Requirements for the 

Independent Storage of Spent Nuclear Fuel, High-Level Radioactive Waste, and Reactor-Related 

Greater than Class C Waste@ (10 CFR Part 72), U.S. Nuclear Regulatory Commission, 

Washington, DC. 

10. ARecommendations for an Effective Flow-Accelerated Corrosion Program@ (NSAC-202L-R3), 

Electric Power Research Institute, Palo Alto, CA.7

11. Code of Federal Regulations, Title 10, Energy, Part 71, APackaging and Transportation 

of Radioactive Material@ (10 CFR Part 71), U.S. Nuclear Regulatory Commission, 

Washington, DC. 

12. Mitchell, M., letter to Libra, R., December 19, 2007, Safety Evaluation of Proprietary EPRI 

Report, "BWR Vessel and Internals Project, Technical Basis for the Reduction of Inspection 

Requirements for the Boiling Water Reactor Nozzle-to-Vessel Shell Welds and Nozzle Inner 

Radius (BWRVIP-108)," ADAMS Accession Number ML073600374. 

13. NRC Spent Fuel Storage and Transportation Division Interim Staff Guidance No. 18 (ISG-18) 

Rev. 1, “The Design and Testing of Lid Welds on Austenitic Stainless Steel Canisters as 

Containment Boundary for Spent Fuel Storage,” U.S. Nuclear Regulatory Commission, 

Washington, D.C. 

 

6

 This interim staff guidance is available electronically through the NRC=s Agencywide Documents Access 

and Management System (ADAMS), http://www.nrc.gov/reading-rm/adams.html, under Accession Number 

ML051520313. 

7

 Copies may be purchased from the Electric Power Research Institute (EPRI), 3420 Hillview Ave., Palo Alto, California 

 94304; telephone (800) 313-3774; fax (925) 609-1310.