ML14143A371
| ML14143A371 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 05/16/2014 |
| From: | Cortopassi L P Omaha Public Power District |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LIC-14-0043 | |
| Download: ML14143A371 (14) | |
Text
LIC-14-0043 May 16, 2014
U.S. Nuclear Regulatory Commission
Attn: Document Control Desk Washington, DC 20555-0001 Fort Calhoun Station, Unit No. 1 Renewed Facility Operating License No. DPR-40 NRC Docket No. 50-285
Subject:
License Amendment Request (LAR) 14-04, Revise Current Licensing Basis to Adopt American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV)
Code,Section III, 1980 Edition, (no Addenda) as an Alternative to Current Code of
Record
References:
- 1. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), "Fort Calhoun Station (FCS) License Amendment Commitment - Piping Code
Discrepancies," dated December 13, 2013 (ML13350A582) (LIC-13-0187) 2. ASME BPV Code,Section III, 1980 Edition, (no Addenda)
In accordance with the commitment contained in Reference 1 and pursuant to 10 CFR 50.90, the Omaha Public Power District (OPPD) hereby proposes to amend Fort Calhoun Station (FCS), Unit No. 1 Renewed Facility Operating License No. DPR-40. Specifically OPPD proposes to revise the Updated Safety Analysis Report (USAR) to allow pipe stress analysis of non-reactor coolant system safety-related piping to be performed in accordance with the ASME BPV Code,Section III, 1980 Edition (no Addenda) (Reference 2) as an alternative to the current Code of Record (i.e., United States of America Standards B31.7, 1968 (DRAFT) Edition).
The Enclosure to this letter provides the basis for this request. Attachments 1 and 2 of the Enclosure contain the associated USAR changes. This LAR has been evaluated in accordance with 10 CFR 50.91(a)(1) using criteria in 10 CFR 50.92(c). OPPD has determined that this LAR involves no significant hazards consideration.
OPPD requests approval of the proposed amendment byMay 15, 2015 and will implement the amendment within 120 days of NRC approval. There are no other regulatory commitments contained in this submittal.
J.
J.
LIC-14-0043 Enclosure Page 1 OPPD's Evaluation of the Proposed Change
1.0
SUMMARY
DESCRIPTION
2.0 DETAILED
DESCRIPTION
3.0 TECHNICAL EVALUATION
4.0 REGULATORY EVALUATION
4.1 Applicable
Regulatory Requirements/Criteria
4.2 Precedent
4.3 Significant
Hazards Consideration
4.4 Conclusions
5.0 ENVIRONMENTAL CONSIDERATION
6.0 REFERENCES
ATTACHMENTS:
LIC-14-0043 Enclosure Page 2 The Omaha Public Power District (OPPD) hereby requests an amendment to Fort Calhoun Station (FCS), Unit No. 1 Renewed Facility Operating License No. DPR-40 revising the current licensing basis (CLB) concerning the design code for non-reactor coolant system (RCS) safety-related piping. Specifically, OPPD proposes to allow pipe stress analysis of non-RCS safety-related piping to be conducted in accordance with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code,Section III, 1980 Edition (no Addenda) (Reference 6.1) (hereafter referred to as the ASME BPV Code). The ASME BPV Code is proposed as an alternative to the current Code of Record (i.e., United States of America Standards (USAS) B31.7, 1968 (DRAFT) Edition (Reference 6.2) (hereafter referred to as USAS B31.7) for pipe stress analysis of non-RCS safety-related piping.
As stated in Appendix G of the Updated Safety Analysis Report (USAR), FCS was licensed in accordance with the 70 draft General Design Criteria (GDC) published for comment in the Federal Register (Reference 6.3), on July 11, 1967 (32 FR 10213). This license amendment request (LAR) seeks to revise USAR Section 1.2, Appendix F, and Appendix G to allow pipe stress analysis of non-RCS safety-related piping to meet the requirements of the ASME BPV Code as an alternative to USAS B31.7. Thus, the scope of this LAR is limited to application of the ASME BPV Code to pipe stress analysis of non-RCS safety-related piping. As stated in Section 4.2.4 of the USAR, reactor coolant loop piping and fittings were designed and fabricated in accordance with the requirements of USAS B31.1 1967 Edition (Reference 6.4) (hereafter referred to as USAS B31.1). OPPD is not requesting a change to the Code of Record for reactor coolant loop piping and fittings, which remains USAS B31.1.
The use of ASME BPV Code requirements to analyze safety-related piping is a common practice throughout the nuclear industry and is endorsed by the NRC in 10 CFR 50.55a, "Codes and standards." Software is commercially available to analyze this piping to the
requirements of the ASME BPV Code whereas similar software for USAS B31.7 is not readily available. Modern software ensures that pipe stress analysis of safety-related piping is performed efficiently and effectively to certify that applicable code requirements are met whereas the lack of such software causes the analysis to be much less efficient and could result in errors or inconsistencies. The application of ASME BPV Code requirements to pipe stress analysis of non-RCS piping as an alternative to USAS B31.7 ensures that the analysis is more effective at determining that appropriate safety standards are met. The amendment will also allow partial resolution of Condition Report (CR) 2013-05206, which identified non-conformances with the original Code of Record for piping analyzed in accordance with the requirements of the ASME BPV Code rather than the requirements of USAS B31.7.
Please note that it is not OPPD's intent to re-perform pipe stress analysis of existing USAS B31.7 piping to the ASME BPV Code. Rather, the ASME BPV Code will be considered an alternative to the USAS B31.7 and will be used in future pipe stress analysis of non-RCS safety-related piping for the reasons noted above. Piping support analysis will continue to LIC-14-0043 Enclosure Page 3 be performed in accordance with the existing licensing basis (i.e., American Institute of Steel Construction (AISC) Manual of Steel Construction, Seventh Edition).
Additionally, the proposed change better aligns the design and procurement requirements of the ASME BPV Code with ASME Section XI. The proposed change provides a clear correlation between the design basis for the design, replacement, and repair of non-RCS
safety-related piping systems, and the inspection and testing requirements of ASME Section XI.
Historical Information
The original licensing of FCS pre-dates much of the regulatory framework that exists today, including design methodologies for evaluating piping stress. Piping at FCS was originally licensed, designed, constructed, and installed to the requirements of USAS B31.1 and USAS B31.7. Specifically, RCS loop piping was designed to the requirements of USAS B31.1 with special requirements for materials and fatigue ana lysis as discussed in the USAR whereas non-RCS safety-related piping was designed to the requirements of USAS B31.7.
The Code of Record for non-RCS safety-related piping has not previously been revised. However, Code reconciliation performed in 1991, (EA-FC-91-054) reconciled the original Code of Record for non-RCS piping (i.e., USAS B31.7) to ASME Section III for repairs and replacements to existing non-RCS safety-related piping in accordance with ASME Section XI. Specifically, EA-FC-91-054 reconciled USAS B31.7 to ASME Section III, 1974 Edition, and/or ASME Section III, 1980 Edition Summer, 1981 Addenda.
The 1991 reconciliation was necessary because manufacturers were unable to provide replacement components in accordance with the original Code of Record. The major differences identified in the 1991 reconciliation were associated with the material
properties (including allowables) of some stainless steels used at FCS. Recognizing that material chemical compositions and processes do change from time to time, the requirement to use material properties from the Code year under which the material was purchased will be maintained. In addition, the method in which fatigue is addressed and accounted for differs between the Codes.
USAS B31.7 provides three methods of analysis for different classifications of piping (i.e.,
Class I, II, and III). For Class II and III piping, USAS B31.7 references USAS B31.1 for a majority of the analysis methodology with some special considerations while the methodology for Class I piping is contained completely within USAS B31.7. Within USAS B31.7 and B31.1, considerations for fatigue were integrated into the analysis methodologies. It should be noted that USAS B31.7, which effectively includes USAS B31.1 by reference, was incorporated into Section III of the ASME BPV Code. Although it was generally agreed that the recommended procedures of USAS B31.7 were safe and conservative by those who reviewed them in detail, further developments of simplified formulas occurred when the piping code was combined into ASME Section III.
LIC-14-0043 Enclosure Page 4 The following paragraphs describe the differences between USAS B31.7 and the ASME BPV Code regarding fatigue considerations for Class I, II, and III piping.
Comparison of USAS B31.7 with Section III of the ASME BPV Code
Reference 6.5 provides a discussion of the differences between USAS B31.7 and the ASME BPV Code for analysis of Class I piping. A summary of the differences is as follows:
The rules in the ASME BPV Code concerning simplified elastic-plastic analysis have their origins in the development of detailed stress analysis for nuclear power piping components under USAS B31.7. In the process of developing USAS B31.7, the frequently occurring large primary plus secondary stresses in piping components required a simplified procedure to evaluate these effects. Thus, a detailed procedure was implemented in the USAS B31.7 code based on tests of notched bar specimens that measured the strain concentrating affect when the 3S m limit was exceeded. At the time, writers of ANSI B31.7 (i.e., USAS B31.7) noted that:
- 1. Stresses caused by a linear through-the-wall temperature gradient T 1, should be considered to be part of S
- n. In the shakedown evaluation T 1 is the source of bending stresses that, in combination with a membrane stress (e.g., from pressure) can cause cyclic plasticity or ratcheting. 2. Test data on piping products were available (e.g., Markl) that show that, even for S > 3S m, the product could withstand a significant number of cycles without failure.
In the original concept of the elastic-plastic correction as implemented in USAS B31.7, a limit of 250 cycles is used, below which no specific account was required to assure that ratcheting would be negligible. In contrast, the ASME BPV Code has no such limitation. However, it should be noted that in the simplified elastic-plastic evaluations of Subsection NB of the ASME BPV Code, if the requirements of equation 10 cannot be met, the simplified elastic-plastic evaluation requires that the range of primary plus secondary membrane bending stress intensity excluding thermal bending stress must always be less
than 3S m.
Further, the simplified evaluation places limits on the range of thru wall temperature gradient to ensure that ratcheting does not occur. In addition, the conservative values of
the K e factors drastically reduce the allowable fatigue cycles. Satisfying these requirements provides assurance that a negligible amount of ratcheting can occur. Therefore, no additional requirement for limiting cycles due to ratcheting is necessary when using the ASME BPV Code for Class I piping analysis. Additionally, Appendix A of Reference 6.5 compares alternating stresses versus allowable cycles for two commonly used piping materials based on the simplified elastic-plastic evaluation rules of the ASME BPV Code and USAS B31.7. The conclusion of this comparison is that, considering the accuracy involved, the methods using the K e factor in the ASME BPV Code is equivalent to the method used in USAS B31.7 for fatigue when S n > 3S m. Thus use of the ASME BPV Code is considered equivalent to the USAS B31.7 Code for Class I piping stress and fatigue analysis.
LIC-14-0043 Enclosure Page 5 Reference 6.6 provides a detailed discussion of the differences between the USAS B31.7 Code and the ASME BPV Code for Class 2 and 3 piping. A summary of the differences is as follows:
For Class 2 and 3 piping, the evaluation of fatigue was performed by the use of stress intensification factors (SIF), which are fatigue correlation factors that compare the fatigue life of piping components (for example, tees and elbows) to that of girth butt welds in straight pipe subjected to bending moments. The ASME BPV Code defines the SIF as "the ratio of the bending moment producing fatigue in a given number of cycles in a straight pipe with a girth butt weld to that producing failure in the same number of cycles in the fitting or joint under consideration." The use of SIF constitutes a simplified method to address fatigue caused by thermal cycles that results in an alternating stress. For Class 2 and 3 piping, there are also differences between the USAS B31.7 Code and the ASME BPV Code in how the combined moments are utilized to calculate stresses. In the USAS B31.7 Code, the SIF "i" is applied only to the two bending moments and is not applied to the torsion moment. The resultant bending intensified moments are then divided by the pipe section modulus to determine the longitudinal stress in the pipe. In the ASME BPV Code, the SIF is applied to the unintensified stress calculated from the resultant moment. At the component level, the SIF is applied to all three moment components (i.e., bending and torsion). Additionally, for the ASME BPV Code, a 0.75 factor is applied to the SIF for sustained (i.e., deadweight) and occasional (e.g., seismic and other dynamic accident type) loads. The product of the SIF multiplied by 0.75 cannot be less than 1. The 0.75 factor is not applied to thermal loads in equations 10 or 11.
The ASME BPV Code's removal of some conservatism when applied to sustained loads and occasional loads is appropriate since none of these loads cause a large number of fatigue cycles (i.e. alternating stresses). This approach is consistent with the Code defined application of SIF. In addition, the ASME BPV Code stresses are conservative relative to USAS B31.7 due to the application of the stress intensification factor to all three moment components.
It should be noted that the USAS B31.7 Code states, "" This philosophy is evident from subsequent development of the ASME BPV Code. Over time, more accurate and improved methods have been added. The ASME BPV Code is therefore considered equivalent to, or better than the original USAS B31.7 Code from which it evolved. This position is supported by ANSI B31 Code Case Interpretation No. 115, "Accept Rules of Section III ASME Boiler and Pressure Vessel Code," which states:
"The rules for the construction of piping that are given in Section III of the ASME Boiler and Pressure Code is identical to those of ANSI B31.7, 1969 Nuclear Power Piping, except for revisions to Section III that have been made since 1971.
Since there has been no parallel updating of B31.7, may the rules of Section III of the ASME Boiler and Pressure Vessel Code as amended by addenda and new editions be accepted in construction of Nuclear Power Plants for piping where B31.7 requirements are applicable."
LIC-14-0043 Enclosure Page 6 It is the opinion of the committee for B31.7, that piping that has been designed and constructed in accordance with Section III of the ASME Boiler and Pressure Vessel Code including addenda and applicable cases may be accepted as complying with the requirements of B31.7, 1969 and applicable addenda for the respective class of construction. The Section III requirements represent the best opinions on these subjects subsequent to the last issue of B31.7."
This Code Interpretation documents the fact that the Code Committee for B31.7 has accepted that ". . . .Section III of the ASME Boiler and Pressure Vessel Code including addenda and applicable cases may be accepted as complying with the requirements of
B31.7 code and applicable addenda for the respective class of construction." Although ANSI B31 Code Case Interpretation No. 115 references USAS B31.7, 1969, that revision of the Code is virtually the same as the 1968 (DRAFT) Edition, which is the current Code of Record for FCS.
Therefore, it is appropriate to allow the ASME BPV Code as an alternative to the original Code of Record for conducting pipe stress analysis of non-RCS, safety-related piping.
Design Criterion Fort Calhoun Station was licensed for construction prior to May 21, 1971, and at that time committed to the draft General Design Criteria (GDC) reflected in Appendix G of the FCS USAR, which are similar to 10 CFR 50, Appendix A, . The draft GDC that are most applicable to piping analysis are Criterion 2, 9, and 40.
LIC-14-0043 Enclosure Page 7
Code of Federal Regulations: 10 CFR 50.55a, Codes and standards (Reference 6.7) contains the following discussion regarding use of the ASME BPV Code:
LIC-14-0043 Enclosure Page 8
Regulatory Guide 1.84, "Design, Fabrication, and Materials Code Case Acceptability, ASME Section III" Regulatory Guide (RG) 1.84 (Reference 6.8) states in part:
"Provisions of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code have been used since 1971 as one part of the framework to establish the necessary design, fabrication, construction, testing, and performance requirements for structures, systems, and components important to safety."
Evaluation A review of the applicable Design Criteria from USAR Appendix G, 10 CFR 50.55a, and RG 1.84 shows that:
Revising the CLB to allow pipe stress analysis of non-RCS safety-related piping to be performed in accordance with the ASME BPV Code as an alternative to USAS B31.7 continues to ensure that the requirements of USAR Appendix G, Criterion 2, 9, and 40 are met. As stated above, the ASME BPV Code provides adequate standards for pipe stress analysis of non-RCS safety-related piping. Thus, Criterion 9 will be revised to show that non-RCS safety-related piping (i.e., reactor coolant boundary piping as referenced in Criterion 9) may be analyzed in accordance with the ASME BPV Code as an alternative to USAS B31.7. The plant maintains its ability to safely shutdown and be maintained in a safe shutdown condition during the spectrum of design basis accidents (DBA) specified in the FCS USAR. The ASME BPV Code is one of the standards approved for incorporation by reference in 10 CFR 50.55a. As noted in RG 1.84, the ASME BPV Code is one part of the framework to establish the necessary design, fabrication, construction, testing, and performance requirements for structures, systems, and components important to
safety. Design Basis (USAR) Appendix N of the USAR (Reference 6.9) defines those FCS piping systems that are currently classified as safety-related. Table N-1 of USAR, Appendix N lists the safety classification of FCS piping by system and piping and instrumentation drawing (P & ID)
LIC-14-0043 Enclosure Page 9 number. Table N-2 of USAR, Appendix N correlates the piping system safety classification to the Code of Record as shown below. The piping affected by this change includes non-RCS piping designated as Safety Class (SC)-1, SC-2 and SC-3 piping.
USAR Appendix N, "Reclassification of Systems" is based upon ANSI/ANS-51.1-1983 (Ref. 6.11). ANSI/ANS-51.1 contains methodology to classify all equipment into one of three safety classes according to its importance to nuclear safety, and its capability for maintenance, surveillance testing, and inspection, or into a non-nuclear safety class. (It should be noted that an additional non-conformance was identified by the NRC regarding
OPPD's use of ANSI/ANS-51.1 to classify equipment into safety classes. The resolution of that issue is also tracked by CR 2013-05206 and is being resolved separately from this application.)
The following information is extracted from Table N-2 of USAR Appendix N:
SAFETY CLASS EQUIPMENT CODE OF CONSTRUCTION QUALITY ASSURANCE SC-1 Piping B31.7, Class I - 1968 draft CQE SC-1 Piping System Components Original Contract Specifications CQE SC-2 Piping B31.7, Class II - 1968 draft CQE SC-2 Piping System Components Original Contract Specifications CQE SC-3 Piping B31.7, Class III - 1968 draft CQE SC-3 Piping System Components Original Contract Specifications CQE (The acronym CQE (Critical Quality Element) is defined in Appendix A of the USAR and is the FCS term equivalent to "safety-related.")
Approved Methodologies 10CFR 50.55a, Codes and standards ASME BPV Code,Section III, 1980 Edition (no Addenda) USAS B31.7 1968 (DRAFT) Edition Draft General Design Criteria (GDC) published for comment in the Federal Register (32 FR 10213) on July 11, 1967 Use of ASME BPV Code,Section III has been generically, "in 10CFR50.55a. As shown in Reference 6.10, piping systems at several operating plants (e.g., River Bend Station) were designed using a similar version of the ASME BPV Code.
LIC-14-0043 Enclosure Page 10 The Omaha Public Power District (OPPD) has evaluated whether or not a significant hazards consideration is involved with the proposed amendment(s) by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:
Response: No
The proposed change to the current licensing basis (CLB) allows the use of American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code,Section III, 1980 Edition (no Addenda) as an alternative to the original Code of Record (i.e., United States of America Standards (USAS) B31.7 1968 (DRAFT) Edition) for the design and analysis of non-reactor coolant system (RCS) piping. The American National Standards Institute (ANSI) B31 Code Committee has determined that:
"-piping that has been designed and constructed in accordance with Section III of the ASME Boiler and Pressure Vessel Code including addenda and applicable cases may be accepted as complying with the requirements of B31.7, 1969 and applicable addenda for the respective class of construction."
Although the ANSI B31 Code Committee statement refers to the B31.7, 1969 Edition, there are no significant differences between it and the B31.7 1968 (DRAFT) Edition.
The change involves the substitution of one accepted piping Code for another and not a physical plant change. The Updated Safety Analysis Report (USAR) accident
analysis assumes the proper functioning of safety systems in demonstrating the adequacy of the plant's design. This change does not alter the intended function of any plant equipment nor does it degrade or increase challenges to the performance of safety systems assumed to function in the accident analysis.
The use of ASME BPV Code,Section III, 1980 Edition (no Addenda) analytical methods provides acceptable design results with no reduction in radiological barrier safety margin. Hence, there is no change in radiological barrier performance that would increase the dose to personnel onsite (10 CFR 20) or to the public at the site
boundary (10 CFR 100).
Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated in the USAR.
Response: No
The proposed amendment provides the basis for the use of ASME BPV Code,Section III, 1980 Edition (no Addenda) for stress analysis of non-RCS safety-related piping.
This approach will not introduce any methods or analytical techniques that could LIC-14-0043 Enclosure Page 11 create the possibility of a new or different kind of accident. Application of a Code methodology does not create the possibility of a different kind of accident.
The application of the ASME BPV Code,Section III, 1980 Edition (no Addenda) does not create any new unanalyzed interactions between systems or components. Piping systems will be analyzed in accordance with the Code, which is one part of the framework to establish the necessary design, fabrication, construction, testing, and performance requirements for structures, systems, and components important to safety. The proposed change to the CLB does not create a new failure mechanism or new accident initiator. The proposed amendment does not involve a change in methods governing the operation of plant systems or components.
Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated in the USAR.
Response: No
The Fort Calhoun Station Technical Specifications (TS) ensure that the plant operates in a manner that will ensure acceptable levels of protection for the health and safety of the public. The Technical Specifications ensure that the available equipment and initial conditions for a Design Basis Accident (DBA) as defined in the USAR meet the assumptions in the accident analysis contained in the USAR. The plant safety margins are addressed in the Technical Specification Bases and the USAR.
This proposed amendment revises the CLB to allow the use of ASME BPV Code,Section III, 1980 Edition (no Addenda) for stress analysis of non-RCS safety-related piping. No changes are being made to the physical plant. The use of the ASME BPV Code,Section III, 1980 Edition (no Addenda) does not change, revise, or otherwise affect the current Technical Specifications (TS) or TS Bases. Incorporation of the ASME BPV Code,Section III, 1980 Edition (no Addenda) into the FCS CLB will not affect the current plant design parameters or TS Limiting Conditions for Operation (LCO).
The proposed change does not modify, change, revise, or otherwise affect any current calculations concerning the plant accident analysis or supporting basis for which the TSs, TS Bases, or USAR safety margins were established. Therefore, the proposed amendment does not involve a significant reduction in a margin of safety.
Based on the above, OPPD concludes that the proposed amendment presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c),
and, accordingly, a finding of "no significant hazards consideration" is justified.
In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in LIC-14-0043 Enclosure Page 12 the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
A review of the proposed amendment has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.
Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22 (c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.
6.1. ASME BPV Code,Section III, 1980 Edition 6.2. USAS B31.7, 1968 (DRAFT) Edition
6.3. Draft
General Design Criteria (GDC) published for comment in the Federal Register (32 FR 10213) on July 11, 1967 6.4. USAS B31.1, 1967 Edition 6.5. NUREG/CR-3243, "Comparisons of ASME Code Fatigue Evaluation Methods for Nuclear Class 1 Piping with Class 2 or 3 Piping" 6.6. EPRI Report 1012078, "Background of SIFs and Stress Indices for Moment Loadings of Piping Components, Final Report," June 2005 6.7. 10CFR 50.55a, "Codes and standards"
6.8. Regulatory
Guide 1.84, "Design, Fabrication, And Materials Code Case Acceptability, ASME Section III" 6.9. Fort Calhoun Station USAR, Appendix N, "Reclassification of Systems" 6.10. River Bend Station USAR, Section 3.9 6.11. ANSI/ANS-51.1-1983, "Nuclear Safety Criteria For The Design of Stationary Pressurized Water Reactor Plants"