Text

Response to Request for Additional Information (RAI) for Fort Calhoun Station (FCS) Exigent License Amendment Request (LAR) to Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment
	ML13291A127
Person / Time
Site:	Fort Calhoun
Issue date:	10/15/2013
From:	Cortopassi L; Omaha Public Power District
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	LIC-13-0148
	Download: ML13291A127 (39)
	v • d • e

444 South 16th Street Mall Omaha, NE 68102-2247 October 15, 2013 LIC-13-0148 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station P1-137 Washington, D.C. 20555

References:

1. Docket No. 50-285

2. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), Fort Calhoun Station - Exigent License Amendment Request 13-08 Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment, dated October 6, 2013 (ML13280A089) (LIC-13-0146)

3. Email from NRC (J. Sebrosky) to OPPD (B. R. Hansher), Request for additional information (RAI) for Fort Calhouns Station (FCS) Exigent License Amendment Request (LAR) To Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment, dated October 9, 2013

SUBJECT:

Response to Request for Additional Information (RAI) for Fort Calhoun Station (FCS) Exigent License Amendment Request (LAR) to Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment On October 6, 2013, pursuant to 10 CFR 50.90 and 10 CFR 50.91(a)(6), the Omaha Public Power District (OPPD) submitted an exigent license amendment request (LAR) (Reference 2) proposing to amend Fort Calhoun Station (FCS), Unit No. 1, Renewed Facility Operating License No. DPR-40 by revising the current licensing basis (CLB) pertaining to pipe break criteria for high-energy piping outside of containment.

On October 9, 2013, teleconferences between representatives of OPPD and NRC Staff were held to discuss the LAR. Following the phone call, the NRC emailed (Reference 3) the attached questions.

OPPD agreed to respond by October 15, 2013. The answers to the NRC questions are contained in , and the USAR markup and clean pages are contained in Attachments 2 and 3 respectively.

No commitments to the NRC are contained in this submittal.

If you should have any additional questions or require additional information, please contact Mr. Bill Hansher at (402) 533-6894.

Employment with Equal Opportunity

U. S. Nuclear Regulatory Commission LlC-13-0148 Page 2 I declare under penalty of perjury that the foregoing is true and correct; executed on October 15, 2013.

Sincerely, Louis P. Cortopassi Site Vice President and CNO LPC/SPQ/brh Attachments: 1. Response to Request for Additional Information (RAI) for Fort Calhoun Station (FCS)

Exigent License Amendment Request (LAR) to Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment

2. USAR Markup Pages

3. USAR Clean Pages c: M. L. Dapas, NRC Regional Administrator, Region IV J. M. Sebrosky, NRC Senior Project Manager L. E. Wilkins, NRC Project Manager J. C. Kirkland, NRC Senior Resident Inspector Director of Consumer Health Services, Department of Regulation and Licensure, Nebraska Health and Human Services, State of Nebraska

LIC-13-0148 Page 1 Response to Request for Additional Information (RAI) for Fort Calhoun Station (FCS)

Exigent License Amendment Request (LAR) to Revise Current Licensing Basis of Pipe Break Criteria for High Energy Piping Outside of Containment By letter dated October 6, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13280A089) Omaha Public Power District (the licensee) submitted for Nuclear Regulatory Commission (NRC) approval a license amendment request that would revise the Fort Calhoun Station Updated Safety Analysis Report for pipe break criteria for high energy piping outside of containment. The proposed amendment would allow the use of U.S. Nuclear Regulatory Commission guidance provided in Branch Technical Position Mechanical Engineering Branch 3-1 Revision 2, which allows for the exemption of specific piping sections from postulated failures if certain criteria are met.

Based on a review of the submittal, the NRC staff has determined that the following additional information (RAIs) are required in order to complete its review. The request for additional information was discussed with you on October 9, 2013. It was agreed that a response to these RAIs would be provided by October 15, 2013. Should the NRC determine that these RAIs are no longer necessary prior to the scheduled date, the request will be withdrawn. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1132 or via e-mail at joseph.sebrosky@nrc.gov. The NRC staff has determined that no security-related or proprietary information is contained herein.

Mechanical and Civil Engineering Branch (EMCB)-RAI-1 To exclude postulating high energy (HE) piping breaks (HELBs) and cracks (HELCs) in piping other than class 1 piping outside containment that are required in the stations current licensing basis (CLB), the proposed LAR requests approval to incorporate, in the stations current LB, criteria from selected sections of SRP MEB 3-1, Rev 2 for selected sections of piping systems. According to the proposed LAR, pipe stress analysis required to support MEB 3-1, Rev 2 HELB and HELC stress threshold evaluations will be performed in accordance with the criteria of ASME Section III 1986 edition, which is the code of reference in MEB 3-1, Rev 2. FCSs CLB for HELB and HELC is based on the Atomic Energy Commission (AEC) letter from A. Giambusso to applicants and licensees dated in December, 1972.

The licensee is requested to confirm that when using the stress criteria of the 1986 ASME Section III, the analyses will utilize the material allowable values from the original code of construction for subject piping.

OPPD RESPONSE The analyses will use the material allowable values from the original code of construction for the subject piping when using the stress criteria of 1986 ASME Section III.

LIC-13-0148 Page 2 EMCB-RAI-2 Verify that stresses developed in the pipe pressure boundary wall due to integral welded attachments (IWA) shall be added to the code stress equations. In addition, describe the methodology to address IWAs and whether this methodology is included in the stations current design basis (CDB).

OPPD RESPONSE OPPD has verified that stresses developed in the pipe pressure boundary wall due to integral welded attachments (IWA) will be added to the code stress equations.

MEB 3-1 Section B.1.b.(2) discusses the treatment of welded attachments for piping in containment penetration areas. OPPDs methodology to address IWAs is described in OPPD procedure PED-MEI-6 Current Practice for Load Case Analysis and Component Qualification for B31.7 Class II/III Systems for B31.7 Piping. Per Section 5.5 of that document, integral welded attachment stresses are calculated using Code Cases N-392 and N-318, which add the local attachment stress with the analyzed pipe stress at that location. Alternatively, PED-MEI-6 identifies that methodology provided by Welding Research Council (WRC) Bulletins 107, 256, and 297 can be used. These WRC bulletins are particularly useful for geometries that are outside the Code Case limits. If required, unique finite element analyses can be used to evaluate integral welded attachments. This methodology is therefore part of the station design basis.

EMCB-RAI-3 Verify that pipe stress analysis loadings includes seismic loads and safety relief valve loads along with any other applicable loads from the stations CDB for normal and upset (level A and level B) operating conditions.

OPPD RESPONSE OPPD has verified that safety relief valve loadings, if applicable, and seismic loadings are part of the design of the piping systems per sections 5.1.4, and 5.2 of OPPD procedure PED-MEI-6.

The seismic loadings also are to include building displacements for operating basis earthquake (OBE) and safe shutdown earthquake (SSE) loadings when considering support loads, and include OBE building movements for the consideration of secondary stresses. Dynamic loadings are not considered as part of level A stresses or load combinations. The dynamic loadings are combined with deadweight and pressure loads for consideration of upset pipe stresses (Level B). Additionally, the deadweight and dynamic loadings are combined with thermal loads for consideration of Level B loads on supports, equipment, and anchors.

EMCB-RAI-4 MEB 3-1, Rev 2 provides a definition for a terminal end. Neither the Giambusso letter nor the FCSs licensing basis provide a specific definition for terminal end. MEB 3-1, Rev 2, defines that for piping which is maintained pressurized during normal plant conditions

LIC-13-0148 Page 3 for only a portion of the run up to a closed valve, a terminal end is the piping connection to the closed valve and, therefore, a break postulation is required at that location. The SRP is specific on this item, see MEB 3-1 Rev 2 last sentence in footnote 3. To exclude a break in such a location, described above, the proposed LAR on page seven proposes that this location is not a terminal end based on the terminal end definition of ANSI/ANS-58.2-1988, which has been withdrawn by ANS. The staff has reviewed the ANSI/ANS-58.2-1988 terminal end definition and has determined that it does not provide a definition for a terminal end for the situation of partial pipe run pressurization described above by MEB 3-1 Rev 2. The proposed LAR requests to utilize the MEB 3-1 to exclude breaks required by the CLB. The staff requests that the licensee properly implement MEB 3-1 and postulate a terminal end HELB for this type of situation as described above.

OPPD RESPONSE OPPD requests use of the following specific definition for a terminal end from ANSI/ANS 58.2-1988 (ANSI/ANS 58.2-1988 has a withdrawn status since ANSI Standards are automatically withdrawn after five years if no updates are required.):

That section of piping originating at a structure or component (such as a vessel or component nozzle or structural piping anchor) that acts as an essentially rigid constraint to the piping thermal expansion. Typically, an anchor assumed for the piping code stress analysis would be a terminal end. The branch connection to the main run is one of the terminal ends of a branch run, except where the special case where the branch run is classified as part of a main run (see definition for branch run). In-line fittings, such as valves, not assumed to be anchored in the piping code stress analysis, are not terminal ends.

OPPDs bases for this definition are as follows:

- A definition of a terminal end was not provided in the Giambusso Letter of December 28, 1972, the Errata of January 11, 1973, nor the OPPD submittal dated May 15, 1973.

- The AEC Letter dated July 12, 1973 (the OLeary Letter) provided the following definition of a terminal end:

Terminal ends of pipe runs originate at points of maximum constraint (e.g., connections to vessels, pumps, valves, fittings that are rigidly anchored to structures) terminal ends of branch runs originate at pipe intersections and components that act as rigid constraints.

While the OLeary Letter did not apply to FCS, it provided a definition of a terminal end at the time of licensing for FCS. This definition was consistent with the subsequent definition provided in ANSI 58.2.

- Page 3.6.2-9 of NUREG-0800 SRP 3.6.2 (March 7, 2007) (Ref. A7.15) states The ANSI/ANS 58.2 standard (Ref. A7.16) has been accepted by the NRC.

LIC-13-0148 Page 4 EMCB-RAI-5 The licensee is requested to consider including MEB 3-1, Rev 2 footnote 3 in the proposed LAR. This will provide a clear definition of a terminal end and, thus, avoid complications in determining terminal ends.

OPPD RESPONSE OPPD requests the use of the definition of a terminal end as defined in the response to EMCB-RAI-4. The ANSI 58.2 definition of a terminal end is similar to MEB 3-1, Rev. 2 Footnote 3 (shown below) with the following sentence deleted:

Extremities of piping runs that connect structures, components (e.g., vessels, pumps, valves) or pipe anchors that act as rigid constraints to piping motion and thermal expansion. A branch connection to a main piping run is a terminal end of the branch run, except where the branch run is classified as part of a main run in the stress analysis and is shown to have a significant effect on the main run behavior. In piping runs which are maintained pressurized during normal plant conditions for only a portion of the run (i.e., up to the first normally closed valve) a terminal end of such runs is the piping connection to this closed valve.

EMCB-RAI-6 The proposed LAR requests to add to the CLB MEB 3-1, Rev 2 Section B.1.c(3), which states:

Breaks in seismically analyzed non-ASME Class piping are postulated according to the same criteria as for ASME Class 2 and 3 piping above.

The licensee is requested to incorporate the intent of Footnote 4 which is part of Section B.1.c(3) or provide a justification and basis for omitting it.

OPPD RESPONSE OPPD agrees with the request (note that the Standard Review Plan (SRP) is not applicable to Fort Calhoun Station in terms of its original licensing basis). The following footnote will be added to USAR, Appendix M, Table 2-2, Section B.1.c(3) to meet the intent of Footnote 4:

B.1.c(3) Footnote 4 (as modified)

Footnote 4: Each non-Category I piping system should be designed to be isolated from any Category I piping system by either a constraint or barrier or should be located remotely from the seismic Category I piping system. If isolation of the Category I piping system is not feasible or practical, adjacent non-Category I piping systems should be analyzed similarly to seismic Class I piping. For non-Category I piping systems attached to Category I piping systems, the piping model shall extend through a minimum of one rigid support in each of the three orthogonal directions beyond the safety related boundary. Extending the model farther may be required to provide effective boundary conditions for all load cases at the safety / non-safety break point and conservative support loads on the first restraint beyond the class split. Where an anchor is

LIC-13-0148 Page 5 used for isolation, loads from the non-safety side shall be considered for the anchor qualification. Typically, the analysis model will be extended at least two supports beyond the anchor. More conservative or accurate modeling details, decoupling and enveloping criteria, and Stress Intensity Factors (SIFs) may also be used when revising existing stress models.

EMCB-RAI-7 The proposed LAR requests to add to the CLB MEB 3-1, Rev 2 Section B.3.c(1) to eliminate HELCs in piping equal to or less than 1 inch. The licensee is requested to include all parts of Section B.3.c or to provide justifications and bases for omitting the remainder parts of Section B.3.c.

OPPD RESPONSE OPPD agrees with the addition of B.3.c(2) and B.3.c(3) with the exception of identifying moderate energy lines. B.3.c(4) will be accepted in part with the following exception:

Wetting effects from critical cracks are to be assumed for all critical components located within the vicinity of a critical crack. The basis for this definition is taken from ANSI/ANS 58.2 Section 9.1. This definition allows engineering judgment to determine the local effects of wetting based on the pressure and temperature conditions in the line. For example, case-by-case evaluations may show that the wetting effects from a crack in a low-pressure high-energy system would be limited and would not encompass all safety related components within a room. As noted earlier in the comment response to EMCB-RAI-4, the ANSI/ANS 58.2 standard (Ref. A7.16) has been accepted by the NRC.

Based on the above, the following will be added to USAR Appendix M Table 2-2:

B.3.c(2) (as modified)

For high-energy fluid system piping, the leakage cracks should be postulated to be in those circumferential locations that result in the most severe environmental consequences.

B.3.c(3)

Fluid flow from a leakage crack should be based on a circular opening of area equal to that of a rectangle one-half pipe diameters in length and one-half pipe wall thickness in width.

B.3.c(4) (as modified)

The flow from the leakage crack should be assumed to result in an environment that wets all unprotected components within the vicinity, with consequent flooding in the compartment and communicating compartments. Flooding effects should be determined on the basis of a conservatively estimated time period required to effect corrective actions.

EMCB-RAI-8 The proposed LAR requests to add to the CLB MEB 3-1, Rev 2 Section B.1.e(2) to determine HELCs based on stress threshold. The licensee is requested to add Section

LIC-13-0148 Page 6 B.1.e(3) which provides the HELC requirements for nonsafety related non-analyzed piping or for piping that does not include seismic loads in its analysis.

OPPD RESPONSE B.1.e(3) is consistent with the current plant licensing basis and will be included as a cited MEB 3-1 section. As a result, the following statement will be added to USAR Appendix M, Table 2-2:

B.1.e(3)

Non-safety class piping which has not been evaluated to obtain stress information should have leakage cracks postulated at axial locations that produce the most severe environmental effects.

EMCB-RAI-9 The proposed LAR requests to add to the CLB MEB 3-1, Rev 2 Section B.1.c(2) (b)(ii) to determine HELBs based on stress threshold. The licensee is requested to add Section B.1.c(2) in its entirety or provide justifications and bases for omitted parts of Section B.1.c(2).

OPPD RESPONSE B.1.c(2) will be adopted in its entirety with the noted exception of the definition of a terminal break as identified in RAI Response to EMCB-RAI-4. The following will be included as part of the cited MEB 3-1 sections in USAR Appendix M Table 2-2:

B.1.c(2)

With the exceptions of those portions of piping identified in B.1.b, breaks in Class 2 and 3 piping (ASME Code,Section III) should be postulated at the following locations in those portions of each piping and branch run:

B.1.c(2)(a)

At terminal ends (as defined in EMCB-RAI-4 response)

B.1.c(2)(b)

At intermediate locations selected by one of the following criteria:

B.1.c(2)(b)(i)

At each pipe fitting (e.g., elbow, tee, cross, flange, and nonstandard fitting), welded attachment, and valve. Where the piping contains no fittings, welded attachments, or valves, at one location at each extreme of the piping run adjacent to the protective structure.

B.1.c(2)(b)(ii)

At each location where stresses calculated2 by the sum of Eqs. (9) and (10) in NC/ND-3653, ASME Code,Section III, exceed 0.8 times the sum of the stress limits given in NC/ND-3653.

As a result of piping reanalysis due to differences between the design configuration and the as-built configuration, the highest stress locations may be shifted; however, the initially determined

LIC-13-0148 Page 7 intermediate break locations may be used unless a redesign of the piping resulting in a change in pipe parameters (diameter, wall thickness, routing) is required, or the dynamic effects from the new (as-built) intermediate break locations are not mitigated by the original pipe whip restraints and jet shields.

Footnote 2: For those loads and conditions in which Level A and Level B stress limits have been specified in the Design Specification (including the operating basis earthquake).

EMCB-RAI-10 The proposed LAR requests to add to the CLB MEB 3-1, Rev 2 Section B.1.c(2) (b)(ii) and Section B.1.c(3). The licensee is requested to add Section B.1.c(4) which is applicable to B.1.c(2) and B.1.c(3).

OPPD RESPONSE B.1.c(4) is not part of the original licensing basis and thus OPPD does not desire to add this requirement. OPPD proposes that the evaluation of the effects on protective structures be performed based on identified breaks. This is consistent with the NRCs guidance initiated in 1987 for removing arbitrary intermediate breaks. Licensees are able to remove arbitrary intermediate breaks from their licensing basis without adopting the rules of MEB 3-1 including Section B.1.c(4). OPPD is requesting to remove arbitrary breaks consistent with Generic Letter 87-11 using the stress rules provided in MEB 3-1. As a result, other requirements that pertain to postulating break locations will be consistent with the original licensing basis of the plant. Using these rules consistent with the NRCs guidance for removing arbitrary intermediate breaks from a plants licensing basis, B.1.c(3) will be revised as:

B.1.c(4) (as modified)

If a structure separates a high energy line from an essential component, that separating structure should be designed to withstand the consequences of a pipe break as identified in Section B.1.c(2).

EMCB-RAI-11 The licensee is requested to consider adding to the proposed LAR MEB 3-1, Rev 2 Section B.1.c(5) which is related to the environmental qualification of mechanical and electrical equipment or provide a justification and the basis for omitting this section.

OPPD RESPONSE B.1.c(5) states that safety-related equipment must be environmentally qualified in accordance with SRP 3.11 and that required pipe ruptures and leakage cracks (whichever controls) must be included in the design basis for environmental qualification of electrical and mechanical equipment both inside and outside of containment.

The LAR does not specifically invoke Section B.1.c(5) of MEB 3-1 since SRP 3.11 covers the environmental qualification of both mechanical and electrical equipment and OPPD is not

LIC-13-0148 Page 8 proposing a change to how environmental qualification of equipment important to safety is conducted at Fort Calhoun Station. The following information is provided to clarify why OPPD is not proposing a change to how environmental qualification is implemented.

SRP 3.11 is specifically related to environmental design basis requirements cited in General Design Criterion (GDC) 4 of 10CFR50 Appendix A. Fort Calhoun Station was originally licensed in accordance with the 70 draft General Design Criteria published for comment in the Federal Register (32FR10213) on July 11, 1967. The 1972 Atomic Energy Commission (AEC) letter for HELB (NRC-72-0007) identified that Criteria 40 and 42 of the draft GDCs reflected the requirement contained in GDC 4 of 10CFR50 Appendix A. Criteria 13 of the 1972 AEC letter specifically covers the need to demonstrate environmental qualification by test for the electrical equipment required to function in the steam-air environment resulting from a high energy fluid line break. An NRC Order (NRC-80-0166) requires OPPD to comply with the Division of Operating Reactors (DOR) Guidelines (IEB 79-01B) to satisfy aspects of GDC-4 for electrical equipment environmental qualification. 10CFR50.49 also requires environmental qualification of electrical equipment important to safety, which is consistent with the general design criteria in 10CFR50 Appendix A including GDC-4. Therefore, the existing licensing basis requirements for environmental qualification of electrical equipment are already consistent with the requirements of GDC-4 of 10CFR50 Appendix A.

Fort Calhoun Station does not have a Mechanical Equipment Qualification (MEQ) Program.

Qualification of mechanical equipment is established based on design requirements, procurement specifications, as well as the implementation of maintenance activities.

The following will be added in place of Section B.1.c(5) to be in line with the current licensing basis of the plant:

B.1.c(5) (as modified)

Electrical equipment important to safety must be environmentally qualified in accordance with 10CFR50.49. Required pipe ruptures and leakage cracks (whichever controls) must be included in the design bases for environmental qualification of electrical equipment important to safety both inside and outside containment. Mechanical equipment continues to be qualified based on design requirements, procurement specifications, as well as the implementation of maintenance activities.

EMCB-RAI-12 Enclosure page 6 section 3, 3rd paragraph, states, The application of Generic Letter 87-11 and the identified sections of BTP MEB 3-1 Revision 2 for specific piping systems Clarify what are the specific piping systems to which this sentence applies.

OPPD RESPONSE The specific piping systems to which this statement applies are the charging and letdown piping in the chemical and volume control system (CVCS), steam generator blowdown system piping, and the main steam supply to auxiliary feedwater (AFW) pump FW-10.

LIC-13-0148 Page 9 Balance of Plant Branch (SBPB) RAI 1 To ensure clarity in the revised USAR Appendix M the ellipses used in quoted sections of MEB 3-1 should be removed, and the full paragraph should be included.

OPPD RESPONSE OPPD agrees with the comment and the ellipses used in the quoted sections in the USAR mark-up sections will be removed. For the ellipses identified in Section B.1.c(2)(b), the section will be expanded to include separate entries for Sections B.1.c(2), B.1.c(2)(a), B1.c(2)(b),

B.1.c(2)(b)(i), and B.1.c(2)(b)(ii) as noted in RAI Response EMCB-RAI-9 in the USAR mark-up.

The ellipses will be removed in Table 2 as well for clarity. The following table entry will be revised:

B.1.b.(1)(d):

(ASME Class 2 Piping in Containment Penetration Areas) The maximum stress as calculated by the sum of Eqs. (9) and (10) in paragraph NC-3652, ASME Code,Section III, considering those loads and conditions thereof for which level A and level B stress limits have been specified in the Systems Design Specification (i.e., sustained loads, occasional loads, and thermal expansion) including an OBE event should not exceed 0.8(1.8Sh + SA). The Sh and SA are allowable stresses at maximum (hot) temperature and allowable stress range for thermal expansion, respectively, as defined in Article NC-3600 of the ASME Code,Section III.

SBPB RAI 2 The license amendment request identifies high energy lines as having temperature equal to or greater than 200ºF or pressure greater than 275 psig. However, USAR Appendix M states that high energy lines have design temperature exceeding 200ºF or design pressure exceeding 275 psig. No revisions to the criteria for determining high energy lines were indicated in the USAR Appendix M markup included in the license amendment request. Does the license amendment request modify the criteria used to identify high energy lines at the Fort Calhoun Station?

OPPD RESPONSE The license amendment request does not modify the criteria used to identify high-energy lines.

The license amendment request incorrectly states in Section 3.0 that the current licensing basis requires postulation of ruptures in normally pressurized high-energy lines where the service temperature is equal to or greater than 200°F or the design pressure is greater than 275 psig.

The license amendment request should have stated that the service temperature is greater than 200°F. No change is required for the USAR to address this error in Section 3.0 in the LAR.

Additionally, the first paragraph of USAR, Appendix M, Section 2.2, incorrectly states that the temperature is based on the design temperature. This is corrected in the second paragraph where it identifies that breaks are postulated for those systems where the service temperature of the fluid exceeds 200°F and the design pressure exceeds 275 psig, and only critical cracks are postulated in lines where the service temperature exceeds 200°F or the design pressure exceeds 275 psig. The identification of a high-energy system based on service temperature is

LIC-13-0148 Page 10 also consistent with USAR Table M-2-1 and Section 4.1, as well as the original Giambusso letter.

Thus, the first sentence in USAR Appendix M Section 2.2 will be revised to state:

All systems outside the containment whose service temperatures exceed 200°F or whose design pressures exceed 275 psig are considered to be high-energy systems.

SBPB RAI 3 The license amendment identifies several modifications that were completed to address weaknesses in the station design with respect to high energy line breaks. In particular, modifications EC61599 and EC53866 ensure the station can mitigate a high energy line break in Rooms 13 and 19. Provide a discussion of the methods used to analyze the temperature and pressure transients in Rooms 13 and 19, how the environmental qualification of equipment in these rooms and communicating spaces is addressed, and the leakage detection capabilities credited in mitigating a high energy line break in these rooms.

OPPD RESPONSE The following clarification is provided regarding the HELB related Engineering Changes (ECs) and how these modifications, which include but are not limited to EC61599 and EC53866, relate to the mitigation strategy for high energy line breaks in Rooms 13 and 19 and how these events are addressed from an environmental consequences perspective.

EC 53866, STEAM GENERATOR BLOWDOWN ISOLATION TEMPERATURE SWITCHES provides an auto-isolation function for a Steam Generator Blowdown Line Break (SGBDLB) in Room 13. The objective of this modification was to limit the mass and energy release from a postulated SGBDLB in Room 13 in order to minimize the propagation of steam and humidity to adjacent and other spaces within the Auxiliary Building.

EC 52662, ADD NEW PIPE SUPPORT ON STEAM GENERATOR BLOWDOWN VERTICAL LINE installed a strategically placed pipe support (FWS-290) in Room 13. This support reduced calculated piping stresses to within threshold levels and eliminated the need to postulate a break in the 3 SGBD pipe section above FW-1020.

EC 61599, REPLACE SOCKET WELDS WITH BUTT WELDS IN ROOM 13 was implemented for piping runs in the containment penetration area to the outboard isolation valve in the Letdown, Charging and Steam Generator Blowdown systems. The objective of this modification was to facilitate the 100% volumetric inspections of these lines in accordance with MEB 3-1 Section B.1.b(7) as part of demonstrating that these lines satisfy the break and crack exemption criteria of B.1.b as described in the license amendment request.

The analysis that establishes the environmental response for a HELB in Room 13 covers postulated breaks and cracks in the steam generator blowdown (SGBD) piping downstream of the outboard containment penetrations valves. This analysis uses a NRC-approved

LIC-13-0148 Page 11 methodology to evaluate the environmental response in the Auxiliary Building for a range of postulated line breaks in the CVCS charging and letdown systems, and the steam generator blowdown systems to determine the environmental response for a line break in Auxiliary Building Room 13. The use of the new NRC approved methodology was approved in accordance with 50.59 Evaluation for EC 52009, which confirmed that the use of the NRC-approved methodology represented a previously approved methodology and as such, its use can be implemented via the 50.59 process without the need to obtain a License Amendment.

As a result, the use of the new NRC-approved methodology is not included in the scope of this LAR. The HELB conditions for Room 13 are bounded by the SGBDLB. Multiple breaks and cracks were postulated in the SGBD lines including double guillotine breaks (DGB) in both the 3 inch steam supply lines to the SGBD blowdown tank FW-7 and the 10 inch SGBD vent lines from the blowdown tank to the atmosphere.

The SGBDLB in the FW-7 vent line was initially found to be bounding for area temperatures and humidity due to the long duration of the event. A duration of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and 30 minutes was initially assumed based on operator rounds and operator action. Due to the adverse conditions as a result of this break, auto-isolation of the SGBD system based on area temperature was installed per EC 53866. Temperature switches installed per this modification have been included in the scope of the EEQ program. The auto-isolation of the SGBD lines in Room 13 acts as both a detection and mitigation device for a SGBD line break. Based on the SGBD line break scenario with auto-isolation, all electrical equipment important to safety that is required for a SGBDLB in Room 13 are subject to the FCS EEQ program and have been qualified for the postulated HELB conditions for the required mission time.

Engineering Change EC 61935, REDUNDANT SOLENOIDS FOR YCV-1045A/B AND REDUNDANT PS FOR PS-923 installed redundant solenoids on the Auxiliary Feedwater (AFW) turbine steam supply valves, YCV-1045A and B, to prevent a single active failure from causing these valves to open coincident with a HELB in Room 19.

Engineering Change EC 53202, FW-10 MS SUPPLY PIPING AND SUPPORT UPGRADE FOR HELB CONCERNS CHANGE 2" ELBOWS, ADD SUPPORT, DELETE SUPPORT & MODIFY BARRIERS modified the piping and supports for the 2 steam supply piping to FW-10 to reduce piping stress levels below threshold values for breaks and cracks. This engineering change also modified the guard pipe around the steam line where it penetrates the roof of Room 19, and extended the guard pipe, which protects the switchgear rooms. The change in the guard pipe prevents steam from reaching Room 19 for a pipe rupture inside the guard pipe and provides a vent path to Room 81.

The YCV-1045A and YCV-1045B valves are normally closed air operated valves that fail open on loss of electrical power or instrument air, which open to supply steam from their associated steam generator to power FW-10. This modification also installed a redundant pressure switch (PS-923-1) and redundant control room alarm to alert operators to a potential HELB in Room

19. This provides a redundant trigger to initiate the pre-existing operator action to isolate the FW-10 steam supply line warm-up valves (small bypasses around the steam admission valves, YCV-1045A/B) upon a sensed low pressure in the steam supply line. The guidance for this operator action is contained in Abnormal Operating Procedure (AOP) AOP-28, Auxiliary Feedwater System Malfunctions.

LIC-13-0148 Page 12 The environmental conditions have been defined for a postulated pipe rupture event in Room

19. The break flow into Room 19 is limited due to the presence of throttling valves (MS-366 and MS-368) that are present in the bypass lines around YCV-1045A and YCV-1045B that keep the steam supply line warm up to YCV-1045. Detection of a pipe break in the 2 main steam feed line to the turbine driven Auxiliary Feedwater (AFW) pump (FW-10) is provided by pressure switches that monitor the pressure in the steam supply line and provide an alarm when pressure conditions in the line drop due to a pipe rupture. The response to the alarm involves manual operator actions in Room 81, which is unaffected by a break in Room 19, to close the manual valves to isolate the 1/2 keep warm lines and to gag YCV-1045A and YCV-1045B in the closed position. These manual operator actions terminate the steam discharge into Room 19 prior to the room becoming harsh from an environmental perspective. As a result, Room 19 and communicating spaces are currently classified as mild environment areas for this postulated pipe break event and there is no electrical equipment in Room 19 that is subject to the requirements of the FCS EEQ Program.

The modifications identified above for Room 19 are based on a postulated break at YCV-1045A/B. This break is based on the requirement that a terminal end is required to be postulated at the normally closed valve YCV-1045A/B. However, using the definition provided in ANSI/ANS-58.2, the break at the normally closed valve YCV-1045A/B does not need to be postulated, as the normally closed valve does not represent a rigid constraint in the piping.

Nevertheless, since a terminal end has not been previously defined in the past, it is assumed that the break at the normally closed valve YCV-1045A/B is required.

SBPB RAI 4 It is not clear if the license amendment applies to systems such as low pressure safety injection or shutdown cooling. Clarify whether these systems are within the scope of the high energy line break criteria and if they are not provide a basis for their exclusion.

OPPD RESPONSE The shutdown cooling and low pressure safety injection systems are not within the scope of the high energy line break criteria. The following is the basis for their exclusion:

The current licensing basis requires the postulation of ruptures in normally pressurized high energy systems where the service temperature is greater than 200°F or the design pressure is greater than 275 psig. The systems that are considered normally pressurized as a high energy system are listed in Appendix M of the USAR. In letter LIC-73-0012, OPPD provided the final response to the Giambusso letter. The list of normally pressurized high energy systems was listed in that letter and originally included the following systems:

o Main Steam o Feedwater o Charging o Letdown o Auxiliary Steam

LIC-13-0148 Page 13 o Condensate Return o Steam Generator Blowdown o Sampling o Nitrogen o Hydrogen Based on the list of systems identified above, it is inferred that the normally pressurized description of high energy systems meant normally pressurized as a high energy system. The submittal was accepted in AEC correspondence to OPPD in NRC 73-0043. A later addition for non-safety related auxiliary feedwater system that could be used for normal plant startup and shutdown expanded the USAR list of normally pressurized systems. This LAR does not change the list of systems classified as high energy.

The low pressure safety injection system and shutdown cooling systems are normally pressurized below high energy line conditions but can occasionally operate at high energy conditions. The shutdown cooling system operates as a high energy system briefly, when the reactor coolant temperature falls below 350°F and reactor coolant pressure falls below 300 psia.

However, as the reactor conditions approach cold shutdown conditions, the system operates below the high energy criterion. As a result, both the shutdown cooling and low pressure safety injection systems are not normally pressurized as high energy systems.

Although Fort Calhoun Station is not designed as a SRP plant, there is precedence in SRP 3.6.1 Revision 3, Table 3.6.1-2 for not considering decay heat removal systems as high energy systems. This table lists typical high-energy systems for Pressurized Water Reactors as follows:

Main Steam Line System Main Feedwater Line System Auxiliary Feedwater System Volume Control System Process Sampling System Condensate System Steam Generator Blowdown System This list does not include decay heat removal systems.

LIC-13-0148 Page 1 USAR Markup Pages

Page 1 of 45 USAR - Appendix M Appendix M Postulated High Energy Line Rupture Outside the Containment Rev 14 Safety Classification: Usage Level:

Safety Information Change No.:

Reason for Change:

Preparer:

Sponsor:

Issued:

Fort Calhoun Station

USAR Appendix M Information Use Page 2 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment List of Tables Table M-2 Systems Outside Containment Exceeding 200°F Service Temperature and/or 275 psig Design Pressure ................................................................................................ 7 Table M-2 Portions of Branch Technical Position MEB 3-1 Used...................................... 9 Table M.3 Parameters Used in Steam Blowdown Calculation ......................................... 15

USAR Appendix M Information Use Page 6 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment This submittal deals with the analyses performed for the study and their results. It also defines and describes the modifications which were completed prior to the completion of the first refueling.

Subsequent to the study, NRC Generic Letter 87-11 was issued, which eliminated the requirement to postulate arbitrary intermediate pipe ruptures. A reanalysis of the non-safety-related portions of the Main Steam and Feedwater piping was performed applying the Generic Letter 87-11 criteria and resulted in fewer postulated pipe rupture locations. Hardware associated with certain previously-identified pipe ruptures is, therefore, not necessary, but provides an additional margin of safety and need not be removed.

2.2 Identification of High Energy Systems All systems outside the containment whose design service temperatures exceed 200°F or whose design pressures exceed 275 psig are considered to be high energy systems. For the purposes of this study, those systems which are not normally pressurized were excluded from consideration. Table M.2-1 lists those systems which were investigated.

Ruptures in pipes containing high energy fluid, up to and including the circumferential break of the pipe, were considered for those systems where the service temperature of the fluid exceeds 200°F and the design pressure exceeds 275 psig. Only the "critical" crack was assumed to occur in the piping of those systems where the service temperature of the fluid exceeds 200°F or the design pressure exceeds 275 psig. The size of the "critical" crack was assumed to be one-half the pipe diameter in length and one-half the wall thickness in width.

USAR Appendix M Information Use Page 7 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment Table M-2 Systems Outside Containment Exceeding 200°F Service Temperature and/or 275 psig Design Pressure System Service Design Maximum Temperature, °F Pressure, psig Line Size, in.

Main Steam 550 985 36 Feedwater 438 1335 20 438 985 16 Charging 130 2735 2 1/2 Letdown 550 2485 2 550 650 2 1/2 Auxiliary Steam 365 150 10 Condensate Return 212 10 6 Steam Generator Steam Generator 550 985 5 Blowdown Sampling 600 2485 3/8 Nitrogen 100 2400 1/2 100 275 1 1/2 Hydrogen 100 2400 1/2

USAR Appendix M Information Use Page 8 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment 2.3 Identification of Essential Structures and Equipment A review was completed identifying the essential structures and equipment outside of the containment which would be required to place and maintain the plant in a cold shutdown condition following a postulated rupture outside the containment of a pipe containing high energy fluid with the simultaneous loss of off-site power. These structures and equipment consist of the following:

1. Control Room

2. Room 81 of the Auxiliary Building

3. Auxiliary Feedwater System

a. Auxiliary Feedwater Panel, AI-179

b. Emergency Feedwater Tank

c. Auxiliary Feedwater Pumps

d. Piping, valves, etc.

4. Cable Spreading Room

5. Switchgear Area

6. Electrical Penetration Area

7. Diesel Generators

8. Regulating and Shutdown Control Element Assemblies

9. Main Steam Isolation Valves

10. Main Steam Safety Valves

11. Safety Injection System

12. Raw Water system

13. Pressurizer Pressure and Level Control

14. Steam Generator Blowdown Isolation Valves 2.4 Revised NRC Line Break Criteria For high energy fluid piping systems the criteria for determining the location of pipe ruptures will be as provided in NRC Generic Letter 87-11. In addition, portions of Branch Technical Position MEB 3-1 Revision 2 dated June 1987, Postulated Rupture Locations in Fluid System Piping Inside and Outside Containment which was enclosed with the NRC transmittal of Generic Letter 87-11 is used for determining the location of pipe ruptures for the CVCS charging and letdown, main steam supply to AFW pump FW-10, and steam generator blowdown systems. The applicable sections of MEB 3-1 are identified in Table M-2-2.

USAR Appendix M Information Use Page 9 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment Table M-2 Portions of Branch Technical Position MEB 3-1 Used Section Description Fluid System Piping in Containment Penetration Areas - Breaks and cracks need not be postulated in those portions of piping from containment wall to and including the inboard or outboard isolation valves provided they meet the requirement of the ASME Code,Section III, B.1.b Subarticle NE-1120 and the following additional design requirements:

(ASME Class 2 Piping in Containment Penetration Areas) The maximum stress as calculated by the sum of Eqs. (9) and (10) in paragraph NC-3652, ASME Code,Section III, considering those loads and conditions thereof for which level A and level B stress limits have been specified in the Systems Design Specification (i.e., sustained loads, occasional loads, and thermal expansion) including an OBE event should not exceed 0.8 (1.8Sh + SA). The Sh and SA are allowable stresses at maximum (hot) temperature and allowable stress range for thermal expansion, respectively, as defined in Article NC-3600 of the ASME B.1.b.(1)(d) Code,Section III.

(ASME Class 2 Piping in Containment Penetration Areas) The maximum stress, as calculated by Eq. (9) in NC-3653 under loadings resulting from a postulated piping failure of fluid system piping beyond these portions of piping should not exceed the lesser of 2.25 Sh and 1.8 Sy. Primary loads include those which are deflection limited by whip restraints. The exceptions permitted in (c) above may also be applied provided that when the piping between the outboard isolation valve and the restraint is constructed in accordance with the Power Piping Code ANSI B31.1 (see ASB 3-1 B.2.c.(4)), the piping shall either be of seamless construction with full radiography of all circumferential welds, or all longitudinal and B.1.b.(1)(e) circumferential welds shall be fully radiographed.

(Fluid System Piping in Containment Penetration Areas) Welded attachments, for pipe supports or other purposes, to these portions of piping should be avoided except where detailed stress analyses, or tests, B.1.b.(2) are performed to demonstrate compliance to the limits of B.1.b.(1).

(Fluid System Piping in Containment Penetration Areas) The number of circumferential and longitudinal piping welds and branch connections should be minimized. Where guard pipes are used, the enclosed portion of fluid system piping should be seamless construction and without circumferential welds unless specific access provisions are made to permit inservice volumetric examination of the longitudinal and B.1.b.(3) circumferential welds.

(Fluid System Piping in Containment Penetration Areas) The length of these portions of piping should be reduced to the minimum length B.1.b.(4) practical.

USAR Appendix M Information Use Page 10 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment Table M-2 Portions of Branch Technical Position MEB 3-1 Used Section Description (Fluid System Piping in Containment Penetration Areas) The design of pipe anchors or restraints (e.g., connections to containment penetrations and pipe whip restraints) should not require welding directly to the outer surface of the piping (e.g., flued integrally forged pipe fittings may be used) except where such welds are 100 percent volumetrically examinable in service and a detailed stress analysis is performed to B.1.b.(5) demonstrate compliance with the limits of B.1.b.(1).

(Fluid System Piping in Containment Penetration Areas) Guard pipes provided for these portions of piping in the containment penetration areas should be constructed in accordance with the rules of Class MC, Subsection NE of the ASME Code,Section III, where the guard pipe is part of the containment boundary. In addition, the entire guard pipe assembly should be designed to meet the following requirements and tests:

(a) The design pressure and temperature should not be less than the maximum operating pressure and temperature of the enclosed pipe under normal plant conditions, (b) The level C stress limits of NE-3220, ASME Code Section III, should not be exceeded under the loadings associated with containment design pressure and temperature in combination with a SSE.

(c) Guard pipe assemblies should be subjected to a single pressure test at a pressure not less than its design pressure.

(d) Guard pipe assemblies should not prevent the access required to conduct inservice examination specified in B.1.b.(7). Inspection ports, if used, should not be located in that portion of the guard pipe through the B.1.b.(6) annulus of dual barrier containment structures.

(Fluid System Piping in Containment Penetration Areas) A 100%

volumetric inservice examination of all pipe welds should be conducted during each inspection interval as defined in IWA-2400, ASME Code, B.1.b.(7) Section XI.

With the exceptions of those portions of piping identified in B.1.b, breaks in Class 2 and 3 piping (ASME Code,Section III) should be postulated at B.1.c(2) the following locations in those portions of each piping and branch run:

USAR Appendix M Information Use Page 11 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment Table M-2 Portions of Branch Technical Position MEB 3-1 Used Section Description At terminal ends3 Footnote 3: That section of piping originating at a structure or component (such as a vessel or component nozzle or structural piping anchor) that acts as an essentially rigid constraint to the piping thermal expansion.

Typically, an anchor assumed for the piping code stress analysis would be a terminal end. The branch connection to the main run is one of the terminal ends of a branch run, except where the special case where the branch run is classified as part of a main run. In-line fittings, such as B.1.c(2)(a) valves, not assumed to be anchored in the piping stress code analysis, (as modified) are not terminal ends.

B.1.c.(2)(b) At intermediate locations selected by one of the following criteria:

At each pipe fitting (e.g., elbow, tee, cross, flange, and nonstandard fitting), welded attachment, and valve. Where the piping contains no fittings, welded attachments, or valves, at one location at each extreme B.1.c.(2)(b)(i) of the piping run adjacent to the prospective structure.

At each location where stresses calculated2 by the sum of Eqs. (9) and (10) in NC/ND-3653, ASME Code Section III, exceed 0.8 times the sum of the stress limits given in NC/ND-3653.

As a result of piping reanalysis due to differences between the design configuration and the as-built configuration, the highest stress locations may be shifted; however, the initially determined intermediate break locations may be used unless a redesign of the piping resulting in a change in pipe parameters (diameter, wall thickness, routing) is required, or the dynamic effects from the new (as-built) intermediate break locations are not mitigated by the original pipe whip restraints and jet shields.

Footnote 2: For those loads and conditions in which Level A and Level B stress limits have been specified in the Design Specification (including B.1.c.(2)(b)(ii) the operating basis earthquake).

USAR Appendix M Information Use Page 12 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment Table M-2 Portions of Branch Technical Position MEB 3-1 Used Section Description Breaks in seismically analyzed non-ASME Class piping are postulated according to the same requirements for ASME Class 2 and 3 piping above4.

Footnote 4: Each non-Category I piping system should be designed to be isolated from any Category I piping system by either a constraint or barrier or should be located remotely from the seismic Category I piping system. If isolation of the Category I piping system is not feasible or practical, adjacent non-Category I piping systems should be analyzed similarly to Seismic Class I piping. For non-Category I piping systems attached to Category I piping systems, the piping model shall extend through a minimum of one rigid support in each of the three orthogonal directions beyond the safety related boundary. Extending the model farther may be required to provide effective boundary conditions for all load cases at the safety / non-safety break point and conservative support loads on the first restraint beyond the class split. Where an anchor is used for isolation, loads from the non-safety side shall be considered for the anchor qualification. Typically, the analysis model will be extended at least two supports beyond the anchor. More conservative or accurate modeling details, decoupling and enveloping B.1.c(3) criteria, and stress intensity factors (SIFs) may also be used when (as modified) revising existing stress models.

If a structure separates a high energy line from an essential component, B.1.c(4) that separating structure should be designed to withstand the (as modified) consequences of a pipe break as identified in Section B.1.c(2).

Electrical equipment important to safety must be environmentally qualified in accordance with 10CFR50.49. Required pipe ruptures and leakage cracks (whichever controls) must be included in the design bases for environmental qualification of electrical equipment important to safety both inside and outside containment. Mechanical equipment B.1.c(5) continues to be qualified based on design requirements, procurement (as modified) specifications, as well as the implementation of maintenance activities.

The designer should identify each piping run he has considered to postulate the break locations required by B.1.c. above. In complex systems such as those containing arrangements of headers and parallel piping between headers, the designer should identify and include all such piping within a designated run in order to postulate the number of breaks B.1.d required by these criteria.

USAR Appendix M Information Use Page 13 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment Table M-2 Portions of Branch Technical Position MEB 3-1 Used Section Description With the exception of those portions of piping identified in B.1.b (within Containment Penetrations), leakage cracks should be postulated as follows:

For ASME Code,Section III Class 2 or 3 or nonsafety class (not ASME Class 1, 2, or 3) piping, at axial locations where the calculated stress by the sum of Eqs. (9) and (10) in NC/ND-3653 exceeds 0.4 times the sum B.1.e(2) of the stress limits given in NC/ND-3653.

Non-safety class piping which has not been evaluated to obtain stress information should have leakage cracks postulated at axial locations that B.1.e(3) produce the most severe environmental effects.

B.3.c(1) Leakage cracks need not be postulated in 1 inch and smaller piping.

For high-energy fluid system piping, the leakage cracks should be B.3.c(2) postulated to be in those circumferential locations that result in the most (as modified) severe environmental consequences.

Fluid flow from a leakage crack should be based on a circular opening of area equal to that of a rectangle one-half pipe diameters in length and B.3.c(3) one-half pipe wall thickness in width.

The flow from the leakage crack should be assumed to result in an environment that wets all unprotected components within the vicinity, with consequent flooding in the compartment and communicating B.3.c(4) compartments. Flooding effects should be determined on the basis of a (as modified) conservatively estimated time period required to effect corrective actions.

USAR Appendix M Information Use Page 35 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment 3.6.14 Steam Generator Blowdown Isolation Valves Due to postulated high energy line breaks in the steam generator blowdown lines outside Containment in Room 13, temperature switches were installed that isolate the steam generator blowdown valves on a high room temperature signal.

4. HIGH ENERGY SYSTEMS OTHER THAN MAJOR HIGH ENERGY SYSTEMS 4.1 Identification of High Energy Systems Other Than Major High Energy Systems All systems outside the containment whose service temperatures exceed 200°F or whose design pressures exceed 275 psig are considered to be high energy systems.

For the purpose of this investigation, those systems which are not normally pressurized were excluded from consideration. The main steam and feedwater systems have already been identified as the major high energy systems since they are the two systems, because of line sizes, fluid energy levels and plant arrangement, which would have the greatest potential to inhibit a safe shutdown of the plant in the event of the postulated pipe rupture incident (see Section M.3). The other high energy systems, because of smaller line sizes, lower fluid energy and plant arrangement, offer a lower potential for hindering a safe shutdown of the facility in the event of the postulated rupture. These other high energy systems are the following:

1. Charging

2. Letdown

3. Auxiliary steam

4. Condensate return

5. Steam generator blowdown

6. Sampling

7. Nitrogen

8. Hydrogen

9. Auxiliary Feedwater System (Non Safety Class Portion)

A study was performed to determine what modifications were necessary to protect essential structures and equipment from a postulated rupture in one of these systems.

The results of the study, including the effects of the postulated break, are discussed in Section 4.2 below. Line break criteria are discussed in Section 2.4.

LIC-13-0148 Page 1 USAR Clean Pages

Page 1 of 45 USAR - Appendix M Appendix M Postulated High Energy Line Rupture Outside the Containment Rev 14 Safety Classification: Usage Level:

Safety Information Change No.:

Reason for Change:

Preparer:

Sponsor:

Issued:

Fort Calhoun Station

USAR Appendix M Information Use Page 2 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment List of Tables Table M-2 Systems Outside Containment Exceeding 200°F Service Temperature and/or 275 psig Design Pressure ................................................................................................ 7 Table M-2 Portions of Branch Technical Position MEB 3-1 Used...................................... 9 Table M.3 Parameters Used in Steam Blowdown Calculation ......................................... 15

USAR Appendix M Information Use Page 6 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment This submittal deals with the analyses performed for the study and their results. It also defines and describes the modifications which were completed prior to the completion of the first refueling.

Subsequent to the study, NRC Generic Letter 87-11 was issued, which eliminated the requirement to postulate arbitrary intermediate pipe ruptures. A reanalysis of the non-safety-related portions of the Main Steam and Feedwater piping was performed applying the Generic Letter 87-11 criteria and resulted in fewer postulated pipe rupture locations. Hardware associated with certain previously-identified pipe ruptures is, therefore, not necessary, but provides an additional margin of safety and need not be removed.

2.2 Identification of High Energy Systems All systems outside the containment whose service temperatures exceed 200°F or whose design pressures exceed 275 psig are considered to be high energy systems.

For the purposes of this study, those systems which are not normally pressurized were excluded from consideration. Table M.2-1 lists those systems which were investigated.

Ruptures in pipes containing high energy fluid, up to and including the circumferential break of the pipe, were considered for those systems where the service temperature of the fluid exceeds 200°F and the design pressure exceeds 275 psig. Only the "critical" crack was assumed to occur in the piping of those systems where the service temperature of the fluid exceeds 200°F or the design pressure exceeds 275 psig. The size of the "critical" crack was assumed to be one-half the pipe diameter in length and one-half the wall thickness in width.

USAR Appendix M Information Use Page 7 of 45 Postulated High Energy Line Rupture Rev. 14 Outside the Containment Table M-2 Systems Outside Containment Exceeding 200°F Service Temperature and/or 275 psig Design Pressure System Service Design Maximum Temperature, °F Pressure, psig Line Size, in.

Main Steam 550 985 36 Feedwater 438 1335 20 438 985 16 Charging 130 2735 2 1/2 Letdown 550 2485 2 550 650 2 1/2 Auxiliary Steam 365 150 10 Condensate Return 212 10 6 Steam Generator 550 985 5 Blowdown Sampling 600 2485 3/8 Nitrogen 100 2400 1/2 Hydrogen 100 2400 1/2