ULNRC-05434, CFR50.55a Request: Proposed Alternative to ASME Section X1 Requirements for Replacement of Class 3 Buried Piping

CFR50.55a Request: Proposed Alternative to ASME Section X1 Requirements for Replacement of Class 3 Buried Piping

ML081190648
Person / Time
Site:	Callaway
Issue date:	04/17/2008
From:	Graessle L AmerenUE, Union Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MD6792, ULNRC-05434, ULNRC-05490
Download: ML081190648 (27)

Text

AmerenUE PO Box 620 Callaway Plant Fulton, MO 65251 April 17, 2008 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 ULNRC-05490 WAmneren Ladies and Gentlemen:

II/I DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC COMPANY FACILITY OPERATING LICENSE NPF-30 10CFR50.55a REQUEST: PROPOSED ALTERNATIVE TO ASME SECTION X1 REQUIREMENTS FOR REPLACEMENT OF CLASS 3 BURIED PIPING (TAC NO. MD6792)

Reference:

ULNRC-05434 dated August 30, 2007 In the reference cited above, Union Electric Company (AmerenUE) submitted Relief Request 13R- 10 regarding paragraph IWA-422 1(b) of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI. The Code Edition applicable to the current 10-year Inservice Inspection interval for Callaway Plant is the 1998 Edition (up to and including the 2000 Addenda).

The requested relief request is needed to support the planned replacement of buried steel piping in Callaway's essential service water (ESW) system with polyethylene (PE) piping. For this repair/replacement activity, IWA-422 1(b) would require the new/replacement piping to meet the original Construction Code requirements for the ESW piping. The applicable Construction Code (ASME Section III), however, does not provide rules for the design, fabrication, installation, examination and testing of PE piping. ASME Code Case N-755 provides conditions under which PE material may be used for ASME Section III, Class 3 buried piping systems. AmerenUE therefore requested relief, in the reference cited above, from the noted Code requirements in order to utilize the provision of Code Case N-755 with the exceptions identified in the relief request.

AtLn UA(4 a subsidiary of Ameren Corporation

ULNRC-05490 April 17, 2008 Page 2 AmerenUE's relief request is currently under review by the NRC staff, and from that review the NRC staff has identified the need for additional information. A request(s) for additional information (RAI) has thus been received by AmerenUE, consisting of questions from the NRC staff reviewers.

Pursuant to the RAI(s), Enclosure 1 of this letter contains the responses to six questions from the NRC's Piping and NDE Branch (CPNB) that were received.

electronically on February 29, 2008, as well as six questions from the Mechanical and Civil Engineering Branch (EMCB) that were provided during a meeting with NRC staff on January 23, 2008. (The final EMCB question was received electronically on February 29, 2008.)

Attachment 2 to Enclosure 1 provides a list of additional exceptions that AmerenUE is taking to ASME Code Case N-755.

Given that procurement, construction, and fabrication activities associated with this request are currently proceeding, AmerenUE requests that NRC contact AmerenUE as soon as possible for any questions or concerns that the NRC may have regarding the responses or information provided by this letter. For any questions regarding this letter or its enclosures, please contact Scott Maglio at (573) 676-8719 or Tom Elwood at (573) 676-6479.

Very truly yours, uke H. Graessle Manager - Regulatory Affairs GGY/MDB/nls

Enclosure:

1. Response to Relief Request Questions Attachments:

1) Dow Chemical DGDA-2492 BK 100 Data Sheet

2) Updated AmerenUE Exceptions to Code Case N-755

2. PPI Letter to Dow Chemical

3. Preliminary Stress Calculation 2007-16760

ULNRC-05490 April 17, 2008 Page 3 cc: Mr. Elmo E. Collins, Jr.

Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Mohan C. Thadani (2 copies)

Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop O-8G14 Washington, DC 20555-2738

ULNRC-05490 April 17, 2008 Page 4 Index and send hardcopy to QA File A160.0761 Hardcopy:

Certrec Corporation 4200 South Hulen, Suite 630 Fort Worth, TX 76109 (Certrec receives ALL attachments as long as they are non-safeguards and may be publicly disclosed.)

Electronic distribution for the following can be made via Responses and Reports ULNRC Distribution:

C. D. Naslund A. C. Heflin T. E. Herrmann L. H. Graessle G. A. Hughes S. M. Maglio T. B. Elwood R. D. Myatt C. R. Kiefer S. L. Gallagher L. M. Belsky (NSRB)

Mr. Ron Reynolds, Director (SEMA)

Mr. Edward Gray, Senior REP Planner (SEMA)

Mr. John Campbell, REP Planner (SEMA)

Ms. Diane M. Hooper (WCNOC)

Mr. Dennis Buschbaum (TXU)

Mr. Scott Bauer (Palo Verde)

Mr. Stan Ketelsen (PG&E)

Mr. Scott Head (STP)

Mr. John O'Neill (Pillsbury Winthrop Shaw Pittman LLP)

Mr. Floyd Gilzow (DNR)

ULNRC-05490 ENCLOSURE 1 RESPONSE TO RELIEF REQUEST QUESTIONS Page 1 of20 REQUEST FOR ADDITIONAL INFORMATION ON THE NRC STAFF REVIEW OF RELIEF FROM ASME CODE REQUIREMENTS TO INSTALL POLYETHYLENE PIPING UNION ELECTRIC COMPANY, CALLAWAY PLANT UNIT 1 (TAC MD6792)

DOCKET NO. 50-483 On August 30, 2007, Union Electric Company submitted a request to use polyethylene piping to replace carbon steel piping in the essential service water (ESW) system at Callaway Plant. On January 23, 2008, the U.S. Nuclear Regulatory Commission (NRC) staff met with Callaway representatives to discuss the major issues with the proposed alternative. As discussed in the meeting, the NRC staff has developed the following request for additional information. The following questions from the NRC's Piping and NDE Branch (CPNB) were transmitted electronically on February 29, 2008.

Due to the time interval between the ASME final approval of Code Case N-755 (March 2007) and its publication (October 2007), AmerenUE Relief Request 13R-10 (submitted via ULNRC-05434 dated August 30, 2007) used the final~revision accepted by the ASME Committees (Rev. 9 Duke). The following Requests for Additional Information (RAIs) reference the ASME published version. The Quality Program developed by AmerenUE is based on the Rev. 9 Duke version of the Code Case. To aid the reviewer when required, the paragraph identification from the Rev. 9 Duke version is included as a parenthetical aid below, where applicable.

1. Procedure Qualifications: Section 1-200 provides two processes for fused joint procedure qualifications.

Question:

1.(a) The licensee should identify the procedure qualification process applicable to this proposed alternative.

Response

AmerenUE is using the Standard Fusion Procedure Specification (FPS) per paragraph 1-221 (QF-221).

Question:

1.(b) Paragraph 1-222 lists the procedure essential variables. The procedure should identify all essential variables that affect heat transfer in the fusion process. The essential variables must be controlled to ensure internal soundness, structural integrity, and fabrication repeatability. The essential variables listed in the procedure do not appear to be all inclusive. Pipe wall thickness and ambient temperature also affect heat transfer characteristics. Provide a basis fornot including pipe wall thickness and ambient temperature as essential variables.

Page 2 of 20

Response

The list of essential variables in paragraph 1-222 (QF-222) is all inclusive with the exception of "(d) fusion pressure" which is fusion machine dependent. This item is being removed in Revision 1 of the Code Case.

Pipe wall thickness and ambient temperature are not essential variables because both are directly proportional to the amount of time it takes to have indication of melt entirely around the pipe (to relax heating pressure) and also how long it takes for the required bead size to form. These are the essential criteria (not a specified period of time) that establish when the heater is to be removed and the subsequent fusion accomplished.

Low ambient temperatures are not a concern since all fusing that is anticipated for this project will be done during the spring and summer months, with average ambient temperatures greater than 50'F. Any fusing done below 50'F will require an environmental enclosure to be placed over the work area to control temperature.

Question:

1.(b)(1) Subparagraph 1-132.1 does not treat wall thickness as an essential variable for elevated temperature testing. Provide technical justification for not performing elevated temperature testing on the specific wall thicknesses being used on the essential service water system.

Response

The quality program developed by AmerenUE incorporates standard industry practices and established, approved codes and standards. As indicated above, the Standard Fusion Procedure (FPS) identified in paragraph 1-221 (QF-221) will be used. The "Sustained Pressure Test" of paragraph 1-132 (QF-132) is only required for the qualification of a new FPS, 1-223 (QF-223), and a new FPS is not required.

Note that paragraph 1-132.1 (QF- 132.1) deals with the "Elevated Temperature Sustained Pressure Test" described in ASTM D3035-03a. On review of the ASTM standard paragraph 6.4 the following sentence was found:

"Tests may be conducted on any pipe size, but tests conducted on 6 in. (168 mm) nominal size pipe shall be considered representative of all pipe sizes."

This indicates that the 8-inch pipe referenced in 1-132.1 is representative of all pipe sizes.

The pipe wall thickness is compensated for by Table Tin ASTM D3035-03a.

Question:

1.(b)(2) Paragraph 1-221 has adopted testing criteria from the Plastics Pipe Institute, TR-33/2001, "Generic Butt Fusion Joining Procedure for Field Joining of Polyethylene Pipe." The criteria do not address the variety of material and configurations applicable to Page 3 of 20 polyethylene pipe. Specify the specific material, cell classification, pipe diameter, wall thickness, and representative configurations that will be used for procedure performance demonstration. Discuss the performance demonstrations process for ensuring the procedure's effectiveness for the different essential variable ranges.

Response

The material selected for the project is Dow Chemical, Continuum DGDA-2492 BK 100.

The material is a two reactor "Bimodal" polyethylene. The cell classification is 445574C, which is a stronger material than the 445474C material identified in the Code Case, with similar fusion characteristics (400 - 4507F heater temperature and 60 - 90 psi interfacial fusion pressure). Two pipe diameters will be used: 36-inch DR 9.5 and 4-inch DR 9. As stated above the Standard Fusion.Procedure Specification (FPS) will be used and a performance demonstration is not required.

Question:

1.(b)(3) Paragraph 1-300.3(a) contains the statement that "qualified thickness ranges for base material need not be identical, but these thicknesses shall be adequate to permit fusing of the test coupons." The term "adequate" is an undefined term. Explain if the thickness must be within the procedure's qualified range. If the thickness does not have to be within the procedure qualified range, provide the technical justification for expanding an essential variable without a performance demonstration.

Response

AmerenUE does not intend to perform simultaneous performance qualifications with another organization. All performance qualifications will be done using AmerenUE Fusion Procedure Specifications.

Question:

1.(c) Section 1-220 discusses the process for procedure qualifications. The procedure qualification attests to its joining capabilities through performance demonstration testing.

The demonstration is to establish the procedure effectiveness through and at the range limits of the essential variables. The joints produced by the demonstrations are evaluated with visual, tensile impact, and elevated temperature sustained pressure tests. Satisfying the testing acceptance criteria qualifies the procedure. The ability to trace the qualifications back to the test data is not clear. The licensee should address how a third party, such as the NRC staff, would audit the procedure qualifications and traceability back to the test data.

Response

Paragraph 1-220 (QF-220) provides two methods for the qualification of a Fusion Procedure Specification (FPS):

Page 4 of 20

a. Use the Standard FPS which uses criteria established by TR-33. No demOnstration testing is required for this method.

b. Develop a new FPS when deviations to the Standard FPS are required. This is allowed by 1-221 (b) (QF-221 (b)) and requires demonstration testing specified in paragraph 1-223 (QF-223).

As discussed above AmerenUE is using the Standard Fusion Procedure Specification (FPS). Therefore no testing is required. If a fusion procedure outside the range of the standard FPS is required, the testing required byi-223 (QF-223) will be performed and documented under the AmerenUE Quality Assurance Program.

Question:

1.(d) The above questions also apply for fittings. The licensee should address auditing the procedure qualifications and traceability back to the test data. The licensee should also address examinations of pipe-to-fitting joints.

Response

See the response to question 1.(c) above.

2. Design for Accessibility: Paragraph 1-121 requires visual examination of all accessible surfaces.

Question:

2.(a) The use of high density polyethylene (PE) pipe in Code Class 3 applications is new to the nuclear power industry. The relief request requires visual testing (VT) examination of the pipe and joint outside surfaces. The licensee should address accessibility for VT examinations of PE pipe from the inside surface.

Response

AmerenUE considers "accessible" as being within reach from an open end. The inside surfaces of the 36-inch fittings are accessible during fabrication. The inside surfaces of the 4-inch pipe and fittings are not considered accessible since the nominal inside diameter is less than 3.5 inches.

Because of the distance between joints (often 50 feet), and the nominal inside diameter of the joints (less than 28 inches), the interior of the 36-inch pipe is considered inaccessible to personnel. While remote video inspection could be performed, it has shown to be inconclusive with indeterminate results in similar industry applications.

An additional consideration with regard to interior inspection is the potential for personnel or equipment moving within the pipe to cause damage to the ID surface.

Page 5 of 20 See the response to question 2.(b), as follows, for additional information regarding provisions forfuture access to inside pipe and joint surfaces.

Question:

2.(b) The visual examinations are being used as an indicator of internal pipe and joint soundness. In time, improvements in volumetric examination techniques may result in the ability to detect potential, flaws or flaws may occur that require field examination as part of the corrective action. Since volumetric examinations would provide increased confidence in system integrity, the NRC staff believes that the piping design should include provisions for future access to the inside pipe and joint surfaces. Provide a discussion on the licensee's plans for designing access for future examinations of the inside surface.

Response

Removable spools will be installed that would provide future access to the ID surfaces in each replacement line should suitable remote equipment be developed. Although removable spools will be installed, it is the intent of AmerenUE to install a permanent piping system using a quality program where future examinations are not required. The quality program includes the following:

1. All inspection personnel will be trained as fusing machine operators.

2. Detailed Fusion Procedure Specifications (FPS) will be utilized.

3. Detailed NDE procedures will be utilized:

a. Visual examination procedures will be utilized.

b. Time-of-Flight Diffraction (TOFD) volumetric examination (ultrasonic testing) procedure will be utilized.

4. Detailed Work Control procedures will be utilized.

5. The most advanced type of PE material currently available will be used.

When complete, the PE piping portion of the Essential Service Water system will be tested and maintained in accordance with ASME Section XI.

3. NDE Qualifications: The NRC.staff is interested in NDE procedure and personnel qualifications for examinations of PE piping systems.

Question:

3.(a) Section -5500 provides qualification for nondestructive examination personnel. The guidance in the relief request does not appear adequate for performance-based demonstrations of the VT examinations. The NRC staff is interested in reviewing a specific proposal for VT personnel qualifications. The licensee should address the use of representative (wall thickness, cell classification, joint configuration) pipe and/or fitting samples of acceptable and unacceptable joints (in conjunction with pictures) for training and performance-based VT personnel qualification.

Page 6 of 20

Response

Two different qualifications are required to support the Code Case. As AmerenUE has elected .to use the Owner option (-5530) of the Code Case, VT-1 and VT-2 examiners are being trained to support the project. "Performance-based Demonstrations" will not be used; this is not required by ASME Section V, Article 9, since it is not invoked by Code Case N-755.

VT-1 Existing personnel with VT-1 qualifications will be trained as fusion machine operators in accordance with -5100(b). This training will follow Appendix A (Supplement 9, Appendix A) of the Code Case. VT-1 personnel will perform the receipt examinations and fused joint examinations (-5200(a) & (b)).

VT-2 Existing personnel with VT-2 qualifications will be trained to perform the hydrostatic test inspections required by -6000 of the Code Case. This training requires a 4-hour training class to educate the personnel on PE piping and fusion practices.

Ouestion:

3.(b) The relief request is silent on VT examinations performed from the inside surface of the piping system. Discuss inside surface VT examinations for piping, fused joints, and fittings. Provide the acceptance criteria for VT examinations performed on the inside surface.

Response

The Code Case does not require examinations on the interior surface of the pipe; therefore, ID examinations were not addressed in the Relief Request.

As discussed in the response to question #2 above, visual examinations of fused joints will only be done on the OD fusion beads. The acceptance criteria will be:

a. uniform beads, and

b. cleavage between the bead does not extend below the OD substrate.

The Code Case also requires a receipt examination when the PE material arrives on site.

The personnel performing this examination will be. the trained VT-1 examiners discussed in the response to question 3(a) above. The acceptance criteria for this examination will come from ASTM F714, paragraphs 5.0 to 5.2, in addition to the Code Case requirements.

Page 7 of 20.

Question:

3.(c) Paragraph -2310 does not address internal soundness. By not addressing internal soundness, the industry is implying that PE piping is free of volumetric flaws. Paragraph

-5200 does not address inspection of the pipe ends to ensure internal soundness.

However, field failures indicate the presence of volumetric flaws in the vicinity of the failed joint. Describe inspection responsibilities for examining pipe ends for volumetric flaws (e.g,, voids and inclusions) during the joining process. Provide a description of the training and qualification of individuals carrying out inspection for volumetric flaws in the pipe ends prior to joining. Provide acceptance criteria for flaws detected during the joining process.

Response

Paragraph -5200 does not address in-process examination of the faced pipe ends, because this has not been identified as an industry issue. However, an inspection of the faced pipe ends (both prior to and immediately after heating) is a good workmanship practice, is addressed in the training of all fusion machine operators and inspectors, and is included in the AmerenUE work procedures. The personnel performing the inspections will have received a minimum of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of fusion training as required by the Code Case.

Although volumetric examination will not be performed on the pipe ends prior to fusing, a volumetric examination (TOFD) will be performed on the completed fusion joint.

Question:

3.(d) Paragraph -4130 does not address sample expansion when flaws are detected in the pipe. The presence of volumetric flaws that are exposed by facing the pipe ends during the joining process may indicate a more extensive problem with volumetric flaws.

Provide a specific proposal for disposition of unacceptable volumetric flaws. When a volumetric flaw is detected, describe the actions taken to determine the extent of volumetric flaws in the vicinity of the surfaces to be joined.

Response

Unacceptable material flaws detected at any time during the manufacture, fabrication, and installation necessitates stopping work and generating a Corrective Action Program document in accordance with the AmerenUE Quality Assurance Program. The Corrective Action Program requires an extent of condition evaluation for all such conditions.

Page 8 of 20 Question:

3.(e) An alternative to 3(c) and 3(d) is a volumetric examination of the fused joint.

Paragraphs -5320, 1-120, and 1-300.3 are silent on volumetric examinations. Describe the volumetric examination techniques, and describe the performance demonstration testing used for qualifying personnel and procedures. Provide the acceptance and flaw disposition criteria.

Response

Code Case N-755 requires the following activities to provide assurance of piping and joint integrity:

1. Data acquisition and review of essential variables during the fusion process

2. 100% visual external inspection of all joints

3. Hydrostatic testing To provide added assurance of joint integrity beyond the requirements of Code Case N-755, AmerenUE will perform ultrasonic Time-of-Flight Diffraction (TOFD) examination of all completed, fusion joints, with the exception of portions ofjoints where the geometry prohibits effective examination (i.e. intrados and extrados areas of mitered fitting joints). The UT examiners will be qualified in accordance with SNT-TC-1A.

Since the TOFD technique is a nonstandard ASME inspection method a certain amount of freedom to implement this technique is required. The potential contractor performing the TOFD does not have a 10 CFR 50 Appendix B quality program. To address this requirement, the Contractor will be hired under a non-safety purchase order. The TOFD technique will be demonstrated to the Authorized Nuclear Inservice Inspector. The Contractor's examiners will be qualified in accordance with SNT-TC-1A.

AmerenUE is currently evaluating and refining acceptance criteria based on industry standards (e.g. ASME B31 piping codes). The current acceptance criteria require that any unbonded area in the joint, found as a result of the TOFD, is cause for rejection.

It should be noted that AmerenUE will retain copies of all TOFD joint examinations for future reference.

4. In-Process Testing: The use of PE piping is new to ASME applications which may perform differently in nuclear power plant applications than other industry applications.

Ouestion:

4.(a) The NRC staff is concerned that cold fusion is not sufficiently understood by the industry to develop effective nondestructive examination methods. The NRC staff believes that the licensee needs to develop a program for in-process destructive examinations of the fused joint to detect process weaknesses. The in-process Page 9 of 20 examination should validate material and equipment effectiveness on a routine basis and material, equipment, and operator effectiveness on a random basis. The in-process testing should include sample selection criteria, testing frequency, testing methods, and acceptance criteria. The testing should be at various circumferential locations to address non-uniform flaw distribution in fused joints. Discuss the in-process verification program that will be implemented.

Response

AmerenUE does not currently plan to provide a program for in-process destructive examinations. As discussed above, AmerenUE will perform TOFD examinations in lieu of in-process examinations. The TOFD process will be performed on all installed joints; whereas in-process destructive examination would only be performed on a sampling of uninstalled joints.

Ouestion:

5. Proposed Alternative: The requested alternative should identify the specific parts of the ASME Code Case referenced in the relief request which are being modified for Callaway's specific application, or request an alternative as a stand alone document that does not mention the Code Case. The portion of the request identified as the alternative should avoid mentioning criteria that is not need for the specific application.

Response

Specific sections of Code Case N-755, along with the exceptions requested, were identified in letter ULNRC-05434 dated August 30, 2007. As design, procurement, and installation details have been developed, additional exceptions have been identified. The additional exceptions requested are provided in Attachment 2 to this Enclosure.

6. Other Question:

6.(a) Paragraph -4130 references paragraphs -2900. The referenced Code Case is missing paragraphs -2400 though -2900. You are requested to review the Code Case for missing paragraphs and provide them in your response to this RAI.

Response

The reference to -2900 is a typographic error and is being corrected in Revision 1 of the Code Case. The reference should be -2300.

Enclosure .1 Page 10 of 20 Question:

6.(b) Subparagraph 1-322.1(a) provides criteria on expiration of qualifications. The subparagraph uses the term process which indicates multiple processes exist. In the event of multiple processes, the concern is on the effectiveness of an operator to apply a given procedure with acceptable results. Provide a discussion on the application of the subparagraph and how it will apply to procedures.

Response

Appendix 1 (Supplement 9) is written to accept other fusing processes as they become available. For example, the electro-fusion process could be included in a subsequent revision to the Code Case. The only process AmerenUE has identified and will allow is thermal butt fusion.

Page 11 of 20 The following questions are from the NRC's Mechanical and Civil Engineering Branch (EMCB). The first five questions below were distributed during the January 23, 2008 meeting and were also attached to the NRC meeting minutes dated February 29, 2008 (ADAMS Accession No. ML080380647). There were some minor revisions to the questions as reflected in the meeting minutes. The last (sixth) question was received electronically on February 29, 2008.

Question:

1. AmerenUE indicatedthat PE material with a cell classification of 445574C will be utilized. This PE material has a higher tensile strength than 445474C PE material specified in the code case. Provide the mechanical properties of the 445574C.PE material.

Response

AmerenUE selected the 445574C material, not only because of the higher tensile strength, but because it is a bimodal material and is the most advanced type of PE material currently available. The selected Dow Chemical material (ContinuumDGDA-2492 BK 100) has a high resistance to Slow Crack Growth. PENT testing (ASTM F1473) requires material to resist crack growth for 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> to achieve a rating of"7" (highest number) in the cell classification. The DGDA-2492 BK 100 material has been tested for over 10,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> and did not fail. A data sheet for DGDA-2492 BK 100 is attached (Attachment 1 to this Enclosure). to this RAI response letter provides a letter from the Plastic Pipe Institute (PPI) Hydrostatic Test Board to Dow Chemical on the results of their review of test data to support inclusion into PPI document TR-4, "PPI Listing of Hydrostatic Design Basis (HDB), Hydrostatic Design Stress (HDS), Strength Design Basis (SDB), Pressure Design Basis (PDB) and Minimum Required Strength (MRS) Ratings for Thermoplastic Piping Materials or Pipe."

If the NRC would like to review the data associated with the testing of this material, arrangements can be made with Dow Chemical.

Question:

2. AmerenUE indicated that mitered elbows of less than 90 degrees (i.e., 45 and 22.5 degree) and less than 3 [three] joints may be utilized, while the Code Case specifies three- or five-joint mitered elbows. Address if any test data is available and what stress intensification factor values will be used for mitered joints with less than three joints.

Page 12 of 20

Response

Code Case N-755 does not differentiate between 3- and 5-joint mitered elbows when specifying stress intensification factors. The stress intensification of 2.0 provided in the Code Case will be used for all mitered elbows, including those with less than 3 joints. In cases where mitered elbows with less than 3 joints are used, each segment is limited to 22.50, as specified by the Code Case.

Question:

3. The relief request did not include the piping diameter (Do), wall thickness (t), and dimension ratio (DR) values. Provide this information for the PE pipe sizes proposed for use at Callaway.

Response

Two different sizes of pipe will be used in the project: 1) 36-inch DR 9.5 and 2) 4-inch DR 9.

Fittings will be fabricated from extruded rod stock of at least one DR lower in accordance with the Code Case.

Question:

4. Provide a complete stress analysis calculation package of one buried ESW piping system containing detailed evaluations showing structural integrity, stress margins, and factors of safety.

Response

A preliminary stress analysis calculation is provided as Enclosure 3 to this RAI response letter. This is not a final, approved calculation.

5. AmerenUE stated that the PE piping will be subjected to pressures and temperatures as high as 165 psig [pounds per square inch gauge], and 180'F [degrees Fahrenheit],

which exceed the limitations provided in ASME Code Case N-755. The material properties will be determined by material testing.

Question:

5.a. Provide the material test data for the 445574C PE material for temperatures up to 180 0 F.

Page 13 of 20

Response

AmerenUE has revised the design conditions for the section of open-ended piping between the Control Building and the Ultimate Heat Sink (UHS) Cooling Tower. The revised design conditions are 45 psig at 1750 F.

The DGDA-2492 BK 100 material has been tested at over 500 psi @ 176' F for 2 years with no failures. This is documented in the letter from PPI to DOW Chemical documented in Enclosure 2 to this RAI response letter. As indicated above, if the NRC would like to review the data associated with the testing of this material, arrangements can be made with Dow Chemical.

Question:

5.b. Provide structural integrity evaluations performed for the high pressure, high temperature applications of the PE piping showing stress margins, and factors of safety.

Response

The structural integrity evaluations performed are provided in the calculation provided as discussed in the response to question 4.

Question:

6. Flaw depths of 10 percent of the wall thickness, especially sharp cracks, may not be acceptable from slow crack growth and crack driving force standpoint. Provide additional limitations or evaluations to show acceptable flaw depth based on pipe dimension ratio (DR), pressure, and temperature.

Response

In lieu of the discussion contained in Relief Request 13R-10 (ULNRC-05434), damage to polyethylene piping under the scope of this project will be addressed by:

(1) For 4-inch piping, any section with a flaw exceeding 10% of the wall thickness shall be cut out and replaced.

(2) For 36-inch piping, any section with a flaw exceeding 7% of the wall thickness shall be cut out and replaced.

(3) Any section of piping with a flaw not exceeding 5% of the wall thickness may be left as-is.

Page 14 of 20 (4) All other flaws shalibe removed by blending as follows:

(a) The depression after flaw elimination is blended uniformly into the surrounding surface with a maximum taper not to exceed 3:1 (ratio of width to height).

(b) After flaw elimination, the area will be examined by visual examination to ensure that the flaw has been removed.

(c) If the elimination of the flaw reduces the thickness of the section below the minimum required design thickness, the section of piping containing the flaw shall be cut out and replaced.

Page 15 of 20 Attachment 1 DOW CHEMICAL DGDA-2492 BK 100 Data Sheet Page 16 of.20 Technical Information - Resin for Pipe Extrusion and Pipe Fittings CONTINUUM DGDA-2492 BK Bimodal Polyethylene Resin Industrial Standards Compliance:

ASTM D3350: cell dassification Black- PE445576C" (MRS)

Black- PE445574C" (HDB)

• Plastics Pipe Institute (PPI): TR-4 Black Pipe - CONTINUUMT DGDA-2492 BK 100>"

- ISO PE100 pipe grade - MRS 10 @ 20°0; CRS 6.3 @ 60°C,11 yr

- ASTM PE4710 pipe grade- 1600psi HDil@ 73°F, 1000psi HDB @ 140'F

• National Sanitation Foundation (NSF): Standard 14 and 61

. Black Pipe- DGDA-2492()

Consult the regulations for complete details.

M T

CONTINUUM DGDA-2492 applications where long-term applications include natural gas BK Bimodal Polyethylene hydrostatic strength combined with distribution pipes, large diameter Resin is produced using outstanding resistance to slow industrial piping, mining, sewage, UNIPOLTM II process crack growth, rapid crack and municipal water service lines.

technology. This product propagation, and high melt may be utilized for pipe strength is desired. Suitable Resin Properties Melt Index (I,) @190'C/2.16 kg. 9/10 min ASTM D 1238 0.06 Flow Index (I,) @190°C/21.60 kg, g/10 min ASTM D 1238 5.5 Density (natural resin). q/cc ASTM D 1505 0.949 Density", g/cc ASTM D 1505 0.959 Thermal Stability, 'F (°C) ASTM D 3350 >428 (>220) 0 Mechanical Propertles' Tensile Strength at Yield, psi (MPa) ASTM D 638 3600 (24.8)

Elongation at Break, % ASTM D 638 740 Flexural Modulus, psi (MPa) ASTM D 790, method1, 150,000 (1034) procedure B Notched Izod Impact @ 23'C, ftlbf/in. (J/m) ASTM D 256, method A 9.1 (488)

Brittleness Temperature, °F (°Cl ASTM D 746, procedure A <-103 (<-75)

Slow Crack Growth PENT, hours ASTM F 1473 '10,000 Pipe Propertieso' Hydrostatic Strength @ 20°C/ 1798 psi (12.4 Mpa), hr. ASTM 1598 >100 Hydrostatic Strength fi 80°C/ 798 psi (5.5 Mpa), hr. ASTM 1598 >1000 Resistance to Rapid Crack Propagation', Pc, psi (bar) ASTM F 1589 >174 (>12)

Resistance to Rapid Crack Propagation", Tc, °F (°C) ISO 13477 <0 (<-IS)

Fabrication Conditions: tI) The first ri numbers of the cell classification are based on natural

• Screw Type: High quality HDPE (preferably barrier for complete resin. The last number and letter are based on bladk resin (natural redn plus 6.5% oFNF-0092).

melting) (2) Natural resin extruded under proper conditions with carbon black

• Melt Temperature Range: 380-440'F (193-225'C) masterbhatun DFNF-0092(6.5%).

(3) Typlcalvalues, not to be construed as specications. Usersshould confirm results by their aw* tests.

(4) Compression molded pals prepared according to ASTMD 4703 Procedure C unless otherv~se noted In the test method. Properties vll vary with changes In molding conditions and aging time.

(5) Pipe diameter of 10 inch IPS (25.4 on) and Standard Diameter Ratio (SOR) .1*.

FormNo.782-00101-1205 Page 1 ol 2 "t'Trademark of TheDowChemical Company C'Dow')oran atfliated company of Dew Page 17 of 20 Product The DowChemical Company and itssubsidiaries (Dow) has a fundamental concern for allwho make, distribute, and use its products, and for the environment in which we live. This concern isthe basis for our Product Stewardship Stewardship philosophy by which we assess the safety, health and etvironrmental inormation on our products and then take appropriate steps to protect employee and public health and our environment. The success ofaurProduct Stewardship program rests wah each and every individual involved with Dow products - from the inital concept and research, to manufacture, use, sale, disposal, and recycle ofeach product.

Customer Dow strongly encourages its customers to review both their manufacturing processes and their applications of Dow products from the standpoint of human health and ensiroronental quality to ensure that Dow products are not used in Notice ways for which they are not intended or tested. Dow personnel are available to answer your questions and to provide reasonable technical support. Dfw product literature, including safety data sheets, should be consulted prior to use of Dow products. Current safety data sheets are available from Dow.

Dow Medical Dow willnot knowingly seltorsample any product or service CProduct3 into any commercial or developmental application that is intended for:

Application Policy a. permanent (Long term) contact withinternal body fluids or internal bodytissues. Long term is a use which exceeds 72 cantinuous hours (except 30 days for PELLETHANE TMpolyurethane elastomers);

b. use incardiac prosthetic devices regardless ofthe length oftime involved; (Cardiac prosthetic devices include,.

but are not limited to, pacemaker leads and devices, artificial hearts, heart valves, intra-aortc balloons and control systems, and ventricalar bypass assisted devices);

c. use as a critical component in medical devices that support or sustain human life;or d, use specifically by pregnant women or inapplications designed specifically topromote or interfere with human reproduction.

Additionally, allProducts intended foruse inpharmaceutical applications, other than pharmaceutical packa Ong, must pass the current Pharmaceutical Liability Guidelines.

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It isthe responsibility oathe medical device or pharmaceutical manufacturer to determine that the Dowproduct is safe, lawful, and technically suitable forthe intended use. DOW MAKES NOWARRANTIES, EXPRESS OR IMPLIED, CONCERNING THE SUITABILITY OF ANYDOW PRODUCT FOR USE INMEDICAL APPLICATIONS.

Disclaimer NOTICE: Nofreedom from infringement oaany patent owned by Dowor others is to be inlerred. Because use conditions and applicable laws may differ Irom one location to another and may change with time, the Customer is responsible foedetermining whether products and the informabon in this document are appropriate forthe Customer's use and for ensuring that the Customer's workplace and disposal practices are incompliance with applicable laws and other governmental enactments. Dowassumes no obligation or liability for the information inthis document.

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NOTICE: Ifproducts ire described as'experimental or developmentar: (1)product specifcations may not be tully determined; (2)analysis of hazards and caution inhandling and use are required; and (3)there is greater potential for Dow to change specifications andlor discontinue production.

Additional North America EuropelMiddle East +800-3694-6367 U.S.&Canada: 1-800-441-4369 +32-3-450-2240 Information 1-9W89-32-1426 Mexico: +1-800-441-4369 Latin America South Africa +800-99-5078 Argentina: +54-11-4319-0100 Brazil: +55-11-5188-9222 Colombia: +57-1-319-2100 Asia Pacific +800-7776-7776 Mexico: +52-55-5201-4700 +60-3-7958-3392 www.dowplastics.com Published September 2005

-4ý. FormNo. 782-00101-1205 Page 2 of2 S2*'Trademark ofThe DowChemical Company V'fow') oras affiliatedcompany ol Dow Page 18 of 20 Attachment 2 - Updated AmerenUE Exceptions to Code Case N-755 Supplemental Alternatives to ASME Section XI Requirements for Replacement of Class 3 Buried Piping in Accordance with 10 CFR 50.55a(a)(3)(i)

Reference Code Case N-755 (Version approved by BNCS March 22, 2007)

The following alternatives to Code Case N-755. supplement those identified in AmerenUE Relief Request 13R- 10 (ULNRC-05434).

Material

• Paragraph 2110 - PE material with a cell classification of 445574C will be utilized. The material may contain a color stripe with cell classification of 445574E. (Note that there is no physicaldifference between C and E, other than the color.)

• Paragraph 2320 -In lieu of the discussion contained in Relief Request 13R-10 (ULNRC-05434), damage to polyethylene piping under the scope of this project will be addressed as provided in the body of the response above.

Design 0 Paragraph 1100 - In lieu of the values contained Relief Request 13R-10 (ULNRC-05434), the design pressures and temperatures of the various lines to be replaced will be 165 psig at 95°F, 160 psig at 95°F, or 45 psig at 175°F, as applicable to the specific line.

• Paragraph 3016 - The design factor will be 0.56 or lower. This is currently being addressed in a revision to Code Case N-755.

e Paragraph 3016 - Miner's Rule (in accordance with ISO 13760) will be used to account for operation for 30 days at post-accident conditions and normal operating conditions for the balance of the 40-year design life.

Fabrication and Installation

" Paragraph 4421 - Ends of larger outside diameter (OD) fittings that adjoin smaller OD pipe may be counterbored externally to match the OD of the pipe, using transitional dimensions similar to those provided in Figure -4421.3-1. Heavier-wall segments with larger outside diameter (i.e. "inverted" elbows) will be used for elbow fabrication to minimize flow restriction.

" Paragraph 4520 - Gaskets may or may not be used, depending on the application.

Use of gaskets may not be appropriate in all sizes and thicknesses of HDPE piping. This is currently being addressed in a revision to Code Case N-755.

Page 19 of 20

" Paragraph 4520 - The required HDPE flange joint seating stress and bolt torque will be determined in accordance with the guidance provided in PPI document Technical Note TN-38, "Bolt Torque for Polyethylene Flanged Joints".

• Paragraph 4520 = Following acceptable visual examination, the external fusion.

joint beads may be removed to accommodate installation of the metallic back-up ring.

• Paragraph QF-133.1 - For pipe coupons greater than 1" thick, alternative means-of achieving similar cross-sectional stress at the joint with shorter test specimens (such as using fixed radius rollers) may be used. Bend Test requirements for performance qualification testing are impractical for large diameter heavy-walled piping. To provide added assurance ofjoint integrity beyond the requirements of Code Case N-755, AmerenUE has elected to qualify fusion machine operators on piping of sizes and thickness similar to that used in production.

• TABLE QF-221(a)-I Approximate Melt Bead Size (inches) for >24 to <36 should read: 7/16 to 9/16. This is currently being addressed in a revision to Code Case N-755.

• The Heater Removal and Joint Closure Times provided for heavy-wall pipe are inadequate. The value provided in the Code Case for >1.18" wall thickness is inconsistent with the incremental increases provided for lesser pipe wall thicknesses. It is noted that heater removal time was not identified as an essential variable of TR-33/2001, it was added by ASME.

Table QF-221(a)-2 is revised in part to read:

Max. Heater Plate Removal Pipe Wall Thickness, in to Joint Closure Time 1.18"7to 2.00" 25 seconds

>2.0" to 4.0" 45 seconds

>4.0" to 6.0" 60 seconds This is currently being addressed in a revision to Code Case N-755.

Paragraph QF-222(a)(4) - The list of essential variables contains redundancy.

Fusion Pressure is the same as Interfacial Pressure, and is therefore not considered an added essential variable for Fusion Procedure Specifications. This is currently being addressed in a revision to Code Case N-755.

Page 20 of 20 Examination Paragraph 5321 - For mitered joints, the beads at the extrados may not roll back to the pipe surface, and beads at the intrados may exhibit multiple beads or heavy beads with no cleavage. The profiles of Figures -5321-1 (and QF-121-1 and Supplement 5) do apply to the outside beads along the centerline of such fittings.

This is currently being addressed in a revision to Code Case N-755.

Nameplates, Stampin2 and Reports Paragraph 8110 - Thermal indentation line printing is permitted during pipe manufacture.

This is currently being addressed in a revision to Code Case N-755.

ULNRC-05490 ENCLOSURE 2 PPI LETTER TO DOW CHEMICAL

PLASTICS.PIPE.INSTITUTE" December 15, 2005 Mr. Dane Chang Dow Chemical Company 2301 N. Brazosport Blvd.

Bldg. B-1607 Freeport, TX 77541

Dear Dane:

The DGDA-2492 BK 100 material is currently listed as a PE 100 with an MRS of 10.0 MPa, and a PE 3408 with an experimental grade HDB of 1600 psi at 73 0 F and 1000 psi at 1401F in TR-4.

Based on the information and additional stress rupture data provided with your letter of November 19, 2005 I have been authorized by the Hydrostatic .Stress Board to grant equivalency of this resin to the DGDA-2490 BK 100 material. This new listing will be published in the next revision to TR-4.

Material Temp. MRS/CRS HBD Grade Expiration PPI (MPa) psi Date Dataset DGDA-2492 BK 100 20 0 C 10.0 S 12/31/2010 3080 DGDA-2492 BK 100 (60'C, 11yr) 6.3 S 12/31/2010 3080 DGDA-2492 BK 100 (80'C, 2 yr) 4.0 S 12/31/2010 3080 DGDA-2492 BK 100 73°F 1600 S* 12/31/2010 3080 DGDA-2492 BK 100 140OF 1000 S 12/31/2010 3080 The hydrostatic data submitted meets the requirements to establish equivalency for a modified PE compound as per TR-3, Part F.6. The 23 0 C and 60 0 C data support the LTHS of 1600 psi and 1000 psi, respectively. The 90 0 C data validates the 60 0 C HDB, and all lower temperature HDBs. Analyzing the 23°C, 60 0 C, and 80 0 C data according to ISO 9080 using the 4 parameter model supports the current MRS 10.0 MPa. As requested, the data also supports the CRS value (60 0 C, 11 yrs) of 6.3 MPa, and (80 0 C, 2 yrs) of 4.0 MPa. Since the 80'C data was the highest temperature tested, the CRS (80 0 C, 2 yr) is based on hours of actual testing with no extrapolation. These new ratings are effective this date.

By copy of this letter, NSF will be notified of these new listings for DGDA-2492 BK 100.

There is an initial TR-4 listing fee of $375.00 (PPI member fee) for each material at each temperature. These fees will be added to your 2006 invoice.

Please call me at 202-462-9607 ext. 11 if there are additional questions pertaining to this listing.

Sincerely, Stephen Boros Chairman, Hydrostatic Stress Board CC: Nasrin Kashefi - NSF 1825 Connecticut Ave. NW, Suite 680, Washington DC 20009 P: 202-462-9607 F: 202-462-9779 www.plasticpipe.org