ML20238E341

Provides Info Requested by NRC Bulletin 87-001, Thinning of Pipe Walls in Nuclear Power Plants. Piping in Condensate, Feedwater,Emergency Condensate,Emergency Feedwater,Main Steam,Extraction Steam & Cold & Hot Reheat Sys Researched

ML20238E341
Person / Time
Site:	Fort Saint Vrain
Issue date:	09/09/1987
From:	Robert Williams PUBLIC SERVICE CO. OF COLORADO
To:	Martin R NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20238E343	List: ML20238E341 ML20238E346 ML20238E349 ML20238E354 ML20238E360
References
IEB-87-001, IEB-87-1, P-87310, NUDOCS 8709140285
Download: ML20238E341 (8)

Text

_ - _ - - - - - - - _ -- -

O

=. =--

I O rubiic service- bin $r7cEac201-os40 i September 9, 1987 OckpNottAMS, JR.

Fort St. Vrain wucttAn OPERATIONS Unit No. 1 P-87310 Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Attention: Robert D. Martin Regional Administrator - Region IV Docket No. 50-267

SUBJECT:

Response To NRC Bulletin 87-01

REFERENCES:

See Enclosure 1

Dear Mr. Martin:

Public Service Company of Colorado (PSC) herein provides the information requested by NRC Bulletin 87-01, " Thinning of Pipe Walls In Nuclear Power Plants", for Fort St. Vrain (FSV). Confirmatory Action 6 of SECY 85-370, dated November 22, 1985, (Reference 1) required PSC to perform inservice inspections on several critical areas of high energy piping in the Main Steam, Cold Reheat, Hot Reheat, and Feedwater systems. PSC completed those inspections and reported the results in P-86105, dated March 3, 1986 (Reference 4).

In addition, the following information is provided for each of the five items in NRC Bulletin 87-01. For the purposes of this response, piping in the Condensate, Feedwater, Emergency Condensate, Emergency Feedwater, Main Steam, Extraction Steam, Cold and Hot Reheat systems was researched.

Detailed Responses Item 1:

Identify the codes or standards to which the piping was designed and fabricated.

DO 7

'O  !

_ _ _ - - .. i

P-87310 September 9,.1987 1 .

Response

ANSI B31.1-1967 is the construction code. Piping materials are per the following:

Feedwater - ASTM A106, Grades B and C, with specific requirements of A530 for some applications. Fittings are A234, Gr. WPB, Gr. WPC, or A216 (2" and smaller: A105 or A181, Cl.70) , Gr. WCB, WCC.

Condensate - ASTM A106, Grade 8. Fittings are A234, Gr. WPB. (2"and smaller: ASTM A105 or A181, C1.70)

Emergency Feedwater - ASTM A106, A105 and A530, as applicable. Also, see Response 4C. Fittings are A234, Gr. WPB or WPC, or R16, Gr. WCB or WCC. (2" and smaller:

A105 ora 181,C1.70)

Emergency Condensate - ASTM A106, Gr. B or A105. Fittings are A234, Gr. WPB. (2" and smaller: A105 or A181, C1.60 orc 1.70)

Main Steam - ASTM A335, Gr. P22 or A530. Fittings are A217, Gr. WC9, or A234, Gr. WP22. (1" and smaller: A182, Gr. F22).

Extraction Steam - ASTM A155, Gr. KC70. Fittings are A234, WPC. (2" and smaller: A105 or A181, C1.70)

Cold Reheat - ASTM A106, Gr. B and A515, Grade 60. Fittings are A216, Gr. WCB or A234, Gr. WPB (2" and smaller: A105' or A181, C1.70)

Hot Reheat - ASTM A155, Gr. 2 1/4 Cr, Cl 1, and A335 Gr. P22.

Fittings are A217, Gr. WC9, or A234, Gr. WP22. (2"and smaller: A182, Gr. F22)

Item 2:

Describe the scope and extent of your programs for ensuring that pipe wall thicknesses are not reduced below the minimum allowable thickness. Include in the description the criteria that you have established for:

a. selecting points at which to make thickness measurements

b. determining how frequently to make thickness measurements

c. selecting the methods used to make thi:kness measurements

d. making replacement / repair decisions

Response

PSC presently has on-going programs in place for the inspection of piping in the Condensate and Extraction Steam systems. Before the Surry Unit 2 event. PSC had initiated inspections to check for possible occurrences of erosion -

induced wall thinning in the Extraction Steam and Turbine Vents and Drains systems. This is

a l 1

P-87310 September 9,'1987-reported in Engineering . Evaluation' EE-ISI-0001, Revision C i (Attachment 1) and addresses points a-d of Item 2. After the Surry Unit 2 event, PSC performed inspections in the Condensate system to identify potential occurrences of erosion - corrosion induced wall thinning.. This is reported in Engineering Evaluation EE-ISI-002, Revision A (Attachment 2) and addresses points a-d of Item 2. NRC  ;

Inspection Report 87-05, dated March 16, 1987, indicated that this program (in draft form) showed " evidence of considerable thought and effort". (Reference 11) l Item 3:

For liquid-phase systems, state specifically whether the following factors have been considered in establishing your criteria for selecting points at which to monitor piping thickness (Item 2a):

a. piping material (e.g., chromium content)

b. piping configuration (e.g., fittings less than 10 pipe diameters apart)

c. pH of water in the system (e.g., pH less than 10)  ;

d. system temperature (e.g., between 190 and 500 degrees Fahrenheit) i

e. fluid bulk velocity (e.g., greater than 10 ft/s)

f. oxygen content in the system (e.g., oxygen content less than 50 ppb)

Response

EE-ISI-002, Revision A, (Attachment 2), addresses each point in Item 3 except point C, which was not a factor in selecting points due to the uniform pH level within the area of inspections. '

Item 4:

Chronologically list and summarize the results of all inspections that have been performed, which were specifically conducted for the purpose of identifying pipe wall thinning, whether or not pipe wall thinning was discovered, and any other inspections where pipe wall thinning was discovered even though that was not the purpose of that inspection.

a. Briefly describe the inspection program and indicate whether it was specifically intended to measure wall thickness or whether wall thickness measurements were an incidental determination.

b. Describe what piping was examined and how (e.g., describe the inspection instrument (s), test method, reference thickness, locations examined, means for locating measurement point (s) in subsequent inspections,

c. Report thickness measurement results and note those that were identified as unacceptable and why.

P-87310 September 9, 1987

d. Describe actions already taken or planned for piping that has been found to have a nonconforming wall thickness. If you have performed a failure analysis, include the results of that nalysis. Indicate whether the actions involve repair or replacement, including any change of materials.

Response

PSC contacted Mr. Conrad McCracken, designated NRR Technical Contact, for clarification of "and any other inspections where pipe wall thinning was discovered even though that was not the purpose of that inspection". Since Fort St. Vrain is a relatively old plant, it would be extremely difficult to assure that all information relative to pipe wall thinning was found and reported to the NRC, via this Bulletin response, for the secondary systems. Mr. McCracken indicated that manpower-intensive research was not required and that much information could be gathered "from memory", in order for NRC to '

l understand how widespread the erosion-corrosion problem actually is.

Therefore, PSC has investigated, to the extent possible, the Change l Notice (CN) system, Nonconformance (NCR) program, Station Service Request (SSR) system, Reportable Occurrence (RO) and Licensee Event Report (LER) systems from 1980 to the present, for 2" and larger piping. Although FSV has experienced various wall thinning in smaller lines, that data has not been presented here.

Additionally, PSC has conducted interviews with experienced personnel in the PSC Production, Engineering, Licensing, and QA departments who are/were involved in plant repair efforts. This was done in response to NRC questions (NRC letter, dated December 26, 1985, G-85504, Reference 2) relative to Confirmatory Action 6 of SECY 85-370 (Reference 1) and the results are contained in PSC letter to NRC, P-86004, dated January 3, 1986, Table 6-1, (Reference 3), and excerpts are represented here as Attachment 3.

The detailed response to Item 4 is arranged in three parts: (A) planned inspections, (B) historical occurrences, and a separate

, section (C) for particular problems associated with Emergency l

I Feedwater to the helium circulators.

A) Planned Inspections March 3, 1986 - PSC provided NRC with the. results of inspections performed pursuant to

...Confi rmatory Action 6 of SECY 85-370 dieference 1) in PSC letter P-86105, dated March 3, 1986. This is Reference 4 and addresses details requested by Item 4, points a-d. '

October 2, 1986 - PSC initiated Engineering Evaluation EE-ISI-0001, Revision C (approved October 2, 1986) for inspection of piping in the Extraction l Steam and Turbine Vents / Drains systems for

P-87310 September 9,~1987' possible occurrences of erosion - induced wall thinning. ~ This was-in response to INP0 SOER 82-11. EE-ISI-0001.is presented here as Attachment 1 and provides._ details requested by Item 4, points a-d. "

August 7, 1987 - PSC initiated- EE-ISI-002, Revision A, (Attachment 2, approved August 7, 1967) for inspection of the Condensate system piping in response to the Surry Unit 2 event. Specific details _ requested by Item 4, points a-d, are l presented in Attachment 2.

1 B) Historical Occurrences In addition to the information presented in PSC letter P-86004 (Reference 3), with excerpts as Attachment 3, the following information is provided. To'the best of PSC's knowledge and belief, given the limitations of the documentation research capabilities' for secondary systems, the historical occurrences of pipe wall thinning were found to be:

November 30, 1983 - Problems with the bypass flash tank leakoff line to the dearator. (2") were identified on Plant Trouble. Reports (PTR)83-11-0525and 83-11-0526. Subsequently, Station Service.

Requests (SSR) 8450196500 and '450202100 8

replaced lines 2"L32163-021, 2"L32164-D21, and 2"L32140-09 (between V-32314 and M-3219), t on drawing PI-53. Further details are not available at this time.

C) Emergency Feedwater To The Helium Circulators- .

FSV has experienced pipe wall thinning in_1" piping downstream of pressure control valves in the Emergency Feedwater system which are designed to bleed cff any leakuge from the main valves'to the turbine i

water drain tank under the no-flow conditions which normally exist.

This has been reported via Reportable Occurrences (RO) 80-23, 80-32,

' 80-58,82-034, and 83-015 (References 6-10). The final report of R0 80-58, dated October 3, 1984, indicated that Change Notice (CN).1687 changed the valve bodies of PV-21243-1 and PV-21244-1, and a portion of the downstream piping, from carbon steel to stainless steel to be more erosion - resistant. No other corrective action: are planned.

I I

l

P-87310 September 9, 1987 Item 5:

Describe any plans either for revising the present or for developing new or additional programs for monitoring pipe wall thickness.

Response

PSC letter to NRC, P-87018, dated February 13, 1987 (Reference 5),

status of the FSV Inservice was submitted Inspection describing (the overallISIT) Program and the FSV ISIT Program Plan and Testing PSC has committed to submit a draft Program Plan to NRC by April 4, 1988. In that submittal, PSC will include whatever revised, additional, or new pipe wall thinning inspection programs as have i been determined to be prudent.

If there are any questions regarding the information provided in this letter and attachments, please call Mr. M. H. Holmes at (303) 480- '

6960.

Very truly yours, i

R. O. Williams, Jr.

Vice President Nuclear Operations R0W/WMD:dvd Attachments Enclosure cc: Mr. R. Farrell Senior Resident Inspector Fort St. Vrain

_ - _ _ _ . w

__. = . _ _ _

P-87310 September 90 1987 Enclosure 1 References for P-87310

1. SECY 85-370, dated November 22, 1985. (G-85488)

2. NRC letter, Berkow to Walker, dated December 26, 1985. (G-85504)

3. PSC letter, Warembourg to Berkow, dated January 3,1986. (P-86004)

4. PSC letter, Warembourg to Berkow, dated March 3, 1986. (P-96105)

5. PSC letter, Brey to Berkow, dated February 13,198/. (P-87018)

6. Reportable Occurrence 80-23, dated June 6, 1980.

7. Reportable Occurrence 80-32, dated July 15, 1980.

8. Reportable Occurrence 80-58 (final), dated October 3, 1984

9. Reportable Occurrence 82-034, dated September 13, 1982

10. Reportable Occurrence 83-015, dated April 8,1983.

11. NRC Inspection Report 50-267/87-05, dated March 16, 1987. (G-87081) l l

}

.. - J l

-l UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION i

In the Matter Public Service Company of Colorado ) Docket No. 50-267 Fort St. Vrain Unit No. 1 ).

1 AFFIDAVIT R. O. Williams, Jr., being first duly sworn, deposes.and says:

That he is Vice President, Nuclear Operations, of Public Service Company of Colorado, the Licensee herein, that he' has, read the foregoing information and knows the contents thereof, and that the statements and matters set forth therein are true and. correct to the best of his knowledge, information and belief.

s j 4

/ /.46-R. O. Williams, Jr. I Vice President Nuclear Operatier*

STATE OF (Win &+) )

)

COUNTY OF $ men / )

Subscribed and sworn to before me, a Notary Public on this V@' day of (hn/fm /w/ , 1987.

A nub b $lk///r /MAvu' Nofary PublicGS3D fiftfa/M//o N' /;A '!

1hnntnpi la foW My comission expires O/moad2;' ,198f.

9