ML20081K161
| ML20081K161 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 03/22/1995 |
| From: | Richard Anderson NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML19325F532 | List: |
| References | |
| NUDOCS 9503290003 | |
| Download: ML20081K161 (15) | |
Text
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4 Northern States Power Company Prairie Island Nuclear Generating Plant I
1717 Wakonade Drive East Welch, Minnesota 55089 March 22, 1995 l
1 U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 I
Response to NRC Request For Additional Information Related to F* and L* Steam Generator Repair License Amendment Reauest The attached information is being provided in response to your letter dated March 8, 1995 which transmitted NRC Staff questions related to our License Amendment Request dated January 9,1995 which proposed the incorporation of F*
and L* Steam Generator Tube Repair Criteria into the Prairie Island Technical Specifications. An initial response to the March 8, 1995 request for additional information was provided by NSP letter dated March 15, 1995.
Attached are our responses to the remaining questions related to the F* repair criteria from the March 8, 1995 NRC letter.
In order to focus our resources on supporting the review of the F* repair criteria, responses to the NRC Staff questions specific to the L* repair criteria are not being provided at this time. contains information proprietary to Combustion Engineering, Inc.,
it is supported by an affidavit (Attachment 3) signed by Combustion Engineering, the owner of the information. The affidavit sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in Paragraph (b)(4) of 10 CFR Part 2, Section 2.790 of the Commission's regulations.
Accordingly, it is respectfully requested that the information which is proprietary to Combustion Engineering be withheld from public disclosure in accordance with 10 CFR Part 2, Section 2.790 of the Commissions regulations.
ATTACHMENT CONTAINS PROPRIETARY INFORMATION TO BE WITHHELD FROM PUBLIC DISCLOSURE IN ACCORDANCE WITH 10 CFR PART, SECTION 2.790 ji nonnne 1
9503290003 950322 DR ADOCK 05000282
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q USNRC March 22, 1995 Page 2 In this letter we have made no new NRC commitments. Please contact Gene Eckholt (612-388-1121, Ext. 4663) if you have any questions related to the attac ed responses.
Ro er O Anderson Director Licensing and Management Issues c: Regional Administrator.- Region III, NRC Senior Resident Inspector, NRC NRR Project Manager, NRC J E Silberg Attachments: 1.
Response to March 8, 1995 NRC Request For. Additional Information.
- 2. Combustion Engineering, Inc. Report, CEN-620-P, Revision 00
" Series 44 & 51 Design Steam Gener*cor Tube Repair Using a Tube Re-Rolling Technique", March 1995 (Proprietary)
- 3. Combustion En8 neering Affidavit 1
- 4. Westinghouse Letter NSP-95-209, Dated March 13, 1995
ATTACHMENT 1 j
gesponse to March 8. 1995 NRC Recuest For Additional Information The following information is provided in response to requests for additional 1
information received from the NRC Staff related to the Prairie Island License Amendment Request for the F*/L* steam generator repair criteria:
Question A-1:
The calculation of the proposed F* distance utilizes a coefficient of friction of 0.2 (Section 2.2.2).
This value was determined from results of pullout tests. What level of confidence was employed in determining this final value of 0.27 Answer:
The attached Westinghouse letter NSP-95-209 dated March 13, 1995 (Attachment
- 4) describes the basis for the 0.2 coefficient of friction. A confidence level was not assigned.
Instead, a factor of safety of two was used.
Question A-4:
As currently written, the proposed Technical Specification change would allow the partially rolled tube to tubesheet joint to be re-rolled in order to create a new undegraded region for application of the F* criteria.
For the staff to complete its review of the option of re-rolling, please address the following items:
(b) provide the test data on leakage testing on roll expanded tubes and justify its applicability to the case of re-rolling tubes in tubesheets containing corrosion products; and Answer:
The justification for the applicability of leakage test data for F* is the results obtained by Combustion En5 neering under prototypical reroll 1
conditions including both clean and sludge containing crevice conditions, minimum and maximum tubesheet bore hole sizes and minimum and maximum torque settings. These results are summarized in Section 7.7 of Combustion Engineering report CENO-620-P (Attachment 2).
All tests were leak tight with the exception of baked on magnetite. Torque traa$ evaluation will identify tubes with unacceptable tube scale.
Table 7-2 on page 27 of CENO-620-P provides the test results. The Westinghouse leakage test data is described in Item 2 of Westinghouse letter NSP-95-209. Attachment 4).
As noted in Test Case 4 of the Combustion Engineering report, tube pull forces were acceptable even with the baked on s '.udge.
Questions A-5s A-6 and L-1 chrouch 4:
In order to foces out 1: sources on supporting the review of the F* repair criteria, responsns to the NRC Staff questions specific to the L* repair criteria (A-5, A-6 and L-1 through 4) are not being provided at this time.
~.
1 t
.USNRC l
March 22, 1995 Page 3 of 3 t
Indian Point Duestion 2:
Several tests subjected tubes to both an interna 1' pressure and an axial load.
l For the RG 1.121 load tests the licensee-should describe the order.in which these two loads were applied.
If both the pressure and axial loads were increased simultaneously provide details describing the internal pressure vs.
. time and load vs. time loading sequence.
b Answer:
The test procedure used by Combustion Engineering is described in Section 7.3 of CEN-620-P Attachment 2). Times were not recorded.
Leak tests were done before and after cyclic-testing.
Indian Point Ouestion 4:
The tests described in gAW-10195 P attempted to determine whether several variables, not directly included in the equation to determine F* (Question 1) would have an impact on the results. These varx. oles included effects from surface roughness of the tubesheet bore, the yield strength of the tubing, and a larger tubesheet bore. The report concluded that these variables had no effect on the calculated F* 1ength. However, the test matrix does not appear to support the possibility that these variables may interact during testing'.
If the test matrix did not adequately separate each of the variables then the i
conclusion in the report may be erroneous. Describe how the test matrix isolated the effects of yield strength and tubesheet bore surface roughness during the testing.
Answer:
The tubesheet bore surface roughness was smoother in the Combustion Engineering tests than in the Westinghouse tests and therefore a range of roughness from 113 RMS te 90 RMS was found to be acceptable.
The yield strength of tut t e.) ased by Westinghouse was 52 kai and by Conbustion Engineering was 37 kai bog, of which were found to be acceptable.
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ATTACHMENT 2 Combustion Engineering, Inc.
Report CEN-620-P Revision 00 Series 44 & 51 Design Steam Generator Tube Repair Using A Tube Re-Rolling Technique March 1995 (33 Pages)
PROPRIETARY l
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ATTACHENT 3 Combustion Engineering Affidavit 4
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AFFIDAVIT PURSUANT TO 10 CFR 2.790 Combustion Engineering, Inc.
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State of Connecticut
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County of Hartford
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SS.:
I, S. A. Toelle, depose and say that I am the Manager, Nuclear Licensing, of Combustion Engineering, Inc., duly authorized to make this affidavit, and flave reviewed or caused to have reviewed the information which is identified as proprietary and referenced in the paragraph immediately below.
I am submitting this affidavit in conformance with the provisions of 10 CFR 2.790 of the Commission's regulations for withholding this information.
The information for which proprietary treatment is sought is contained in the following document:
CEN-620-P, Revision 00,
" series 44
& 51 Design Steam Generator Tube Repair Using a Tube Re-Rolling Technique,"
FINAL REPORT, March 1995.
This document has been appropriately designated as proprietary.
I have personal knowledge of the criteria and procedures utilized by combustion Engineering in designating information as a trade secret, privileged or as confidential commercial or financial information.
Pursuant to the provisions of paragraph (b) (4) of Section 2.790
of the Commission's regulations, the following is furnished for consideration by the_ Commission in determining whether the information sought to be withheld from public disclosure, included in the above referenced document, should be withheld.
[
1.
The information sought to be withheld from public disclosure, which is owned and has been held in confidence by Combustion Engineering, is t:he design, tests, and analyses related to the development of a technique to repair Westinghouse PWR steam generator Series 44 and 51 tubes using a re-rolling process 2.
The information consists of test data or other similar data concerning a process, method or component, the application of which results in substantial competitive advantage to Combustion Engineering.
3.
The information is of a type customarily held in confidence by Combustion Engineering and not customarily disclosed to the public.
Combustion Engineering has a rational basis. for determining the types of information customarily held in confidence by it and, in that connection, utilizes a system to determine when and whether to hold certain types of information in confidence.
The details of the aforementioned system were provided to the Nuclear Regulatory Commission via letter DP-537 f rom F.
M.
Stern to Frank Schroeder dated December 2, 1974.
This system was applied in determining that the subject document
4 herein is proprietary.
4.
The information is being transmitted to the Commission in confidence under the provisions of 10 CFR 2.790 with the understanding that it is to be received in confidence by the Commission.
5.
The information,"to the best of my knowledge and belief, is not available in public sources, and any disclosure to third parties has been made pursuant to regulatory provisions or proprietary agreements which provide for maintenance of the information in confidence.
6.
Public disclosure of the information is likely to cause substantial harm to the competitive position of Combustion Engineering because:
a.
A similar product is manufactured and sold by major pressurized water reactor competitors of Combustion Engineering.
b.
Development of this information by Combustion Engineering required hundreds of manhours and tens of thousands of dollars.
To the best of my knowledge and belief, a
competitor would have to undergo similar expense in generating equivalent information.
c.
In order to accaire such information, a competitor would also require considerable time and inconvenience to develop t
9 -.,
a similar technique to repair Westinghouse PWR steam generator Series 44 and 51 tubes using a re-rolling process.
d.
The information required significant effort and expense to obtain the licensing approvals necessary for application of the information.
Avoidance oi this expense would decrease a
competitor's cost in applying the information and marketing the product to which the information is applicable.
e.
The information consists of the design, tests, and analyses related to the development of a technique to repair Westinghouse PWR steam generator Series 44 and 51 tubes using a re-rolling process, the application of which provides a
competitive economic advantage.
The availability of such information to competitors woulc enabic them tc modify their product to better compete with Combustion Er,gineering, take marketing or other actions to improve their product's position or impair the position of Combustion Engineering's product, and avoid developing similar data and analyses in support of their processes, methods or apparatus, f.
In pricing Combustion Engineering's products and services, significant research, development, engineering, analytical, manufacturing, licensing, quality assurance and other costs and expenses must be included.
The ability of Combustion Engineering's competitors to utilize such information
without similar expenditure of resources may enable them to sell at prices reflecting significantly lower costs.
g.
Use of the infonnation by competitors in the international taarketplace would increase their ability to mar);et nuclear steam supply systems by reducing the costs associated with their technology development.
In addition, disclosure would have an adverse economic impact on Combustion Engineering's potential for obtaining or maintaining foreign licensees.
Further the deponent sayeth not.
- b. h.
f S. A. Toelle Manager Nuclear Licensing Sworn to before me this /G M day of M aA cd.,
1995
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t2/AA-(A lA
'tfary Publ y o
My commission expires:
2-3/-99
ATTACHMENT 4 Westinghouse Letter NSP-95-209 (3 pages)
Dated March 13, 1995
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~ Westinghouse Energy Systems '
Ba 355
. Electric Corporatib.
Pittsburgh Pennsytvama 15230 0355
-March 13,1995 -
[
. NSis95-209 -
Mr. R. Pearson N'orthern States Power Company t
' Prairie Island Nuclear Generating Plant 1717 Wakonade Drive East i
Welch, MN.55089-9642
Dear Mr. Pearson:
NORTHERN STATES POWER COMPANY PRAIRIE ISLAND UNITS 1 AND 2 '
i RESPONSE TO NSP/NRC REOUEST FOR ADDITIONAL INFORMATION FOR F* AND L' The purpose of this letter is to transmit additional information concerning F* and L* for -
Northern States Power.
1.'
Question A-1 of Reference 1:
The calculation of the proposed F* distance utilizes a coefficient of friction of 0.2 (Section 2.2.2). This value was determined from results of pullout tests.. What level of confidence was employed in determining this final value of 0.27
Response
As stated in Reference 2, Section 2.2.2, two sets of tests were performed, at room temperature, to determine tube-to-tubesheet coefficient of friction. It was expected that room temperature would provide conservative values because of the lack of beneficial,
" thermal tightening", of the higher-expansion tube in the lower-expansion tubesheet unit -
cell simulant (collar).
The first set, involving 10 individual tube-to-tubesheet simulant samples, provided an average value of approximately 0.54.
i The second set for tests involving tube-to tubesheet samples provided friction coefficients
^
for both tube-expelled and tube-immobile-but-leaking conditions. For the tube-expelled-
~ condition, for evo samples, the coefficient was 0.437 and 0.475, per Reference 2.' For the other case, involving three samples, the coefficients were >0.21, >0.27 and >0.39.
(Note: The leakage occurred at primary side pressures of 5,200,10,700 and 20,800 psi.)
For three tube burst cases, no coefficient could be determined.
F r
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e R. Pearson March 13,1995 NSP-95-209 i
On the basis of these results, the use of a friction coefficient of 0.20 was selected as conservative by greater than a factor of two, based on average values.
2.
Question A-4(b) of Reference 1:
its applicability to the case of re-rolled tubes in tubesheets containing corrosion products,
Response
We can discuss only the first part of this question, the leakage testing for roll expanded tubes, because that is the part Westinghouse provided. Another vendor provided the other part.
As related in a phone call with R. Pearson on March 8,1995, we stated in Reference 2, Page 2-9, Section 2.3.1, that the hardrolled joint would be expected to be leak tight. This is based on the fact that per Table 2-4 of Reference 2, that the interference fit pressure between the tube and tubesheet in the joint made in the factory exceeds the maximum prirr.ary to-secondary (fluid) pressure differential by a factor of several. The interference fit pressure, determined to be 3854 psi (a 95%/95% value) at room temperature and increasing to 5673 psi during Normal Operation (N.O.), exceeds the fluid pressure of 1593 psi by a factor of 3.56 at N.O. This is expected essentially to prevent leakage through the tube-to-tubesheet interface. The fact that Alloy 600 tube flows plastically during roll expansion tends to prevent leak paths along tubesheet hole machining marks, helical or even axial in orientation. The leakage tests performed for L*, documented in Table 3-3 of the report, confirms the low leak rates, essentially zero, for sound roll lengths of 1.00 inch, i.e., the approximate value of F*, and above, for the N.O. condition.
The results in Table 3-3 are conservative because of the fact that the 3/4 inch diameter tube leak test data included a correction for tubesheet bow. The correction was detrimental to resistance to leakage. The 3/4 inch SGs had the F* and L* portions of the tube joints in the vicinity of the top of the tubesheet. In the 3/4 inch tube test case, the interference fit pressure was reduced to allow for tubesheet bowing for the limiting tubes, i.e., non-peripheral tubes. This is conservative for NSP because the F* and La portions of the tube joint are in the vicinity of the lower face of the tubesheet and for the limiting tubes, i.e., the peripheral tubes, tubesheet bending does not reduce interference fit pressure.
it should also be noted that the leakage related to the friction coefficient tests in Paragraph 1 above occurred only at very high primary-to-secondary side pressure, i.e.,
over 5,200 psi.
3 R. Pearson
- March 13,1995 NSP-95-209 '
3.
Verbal Question, Reference 3 "What is the typical roughness of the outside surface of S/G tubes?"
Response
The outside surface of tubes in Westinghouse S/Gs, as manufactured is typically 20 AA.
If you have any questions about these responses, please contact me.
Very truly yours, WESTINGilOUSE ELECTRIC CORPORATION da M T. W. Wallace Accoant Manager NSP Project 8
cc:
M. IIeller J. Usem -lY PSFS Minnesota
References:
1)
Request for Additional Information to NSD, Telecopy received from R. Pearson, NSP 2/23/95 2)
WCAP-14225, F* and L* Tube Plugging Criteria for Tubes with Degradation in the Tubesheet Roll Expansion Region of the Prairie Island Units 1 and 2 Steam Generators, December 1994 3)
Telephone Call, R. Pearson to L Nelson, Steam Generator Tube O.D. Typical Roughness,3/9/95
.