IR 05000263/1975002
| ML20024G099 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 03/04/1975 |
| From: | Cook R, Dance H, Erb C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20024G098 | List: |
| References | |
| 50-263-75-02, 50-263-75-2, NUDOCS 9102070530 | |
| Download: ML20024G099 (7) | |
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U. S. NUCLEAR REGULATORY C0:tt1SS10N OFFICE OF INSPECTION AND ENFORCEMENT
REGION III
Report of Operations Inspection
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IE Inspectio: Report No. 050-263/75-02 Licensce: Northern States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401 Monticello Nuclear Generating Plant License No. DPR-22 Monticello, Minnesota Category: C Type of Licensee:
BWR (GE), 595 }Ne Type of Inspection:
Special, Announced Dates of Inspection:
January 23 and 24, 1975 Dates of Previous Inspection:
January 15-17, 1975 (Operations)
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Principal Inspector:
R. J.
ook
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{y Accompanying Inspector:
C. M. Erb Other Accompanying Personnel:
Ncne C
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I Reviewed By:
H. C. Dance l
Senior Heactor Inspector (lia te)
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9102070530 750304 PDR ADDCK 05000263 O
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SUMMARY Or TIND?NCS i t44 Enforcement Action:_ None Licenace Action on Previously Identified Enforcement Matters:
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None inspected.
Unusual Occurences Indications of cracking at fitting welds in both recirculation pump discharge valve 4 inch by-pans lines was detected by ultrasonic
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examination as per RO Bulletin 10A.
(Paragraph 7)
Other Significant Findings A.
Current Find _ints: None B.
Unresolved Matters:
None C.
Status of Previous 1v Reported Unrerolved Matters _;
None Inspected.
Management Interview A management interview was conducted by Messrs. Cook and Erb with' Messrs.
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Kruspos, harcsen, Swedberg and 'Ior tvauran at the coupletion of the inspection.
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The following items were discussed
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External forces applied to the piping system was discussed.
The A.
licensee stated that an attempt would be made to measure piping spring back when the original pipe is cut.
(Paragraph 5)
B.
Confirmation of as built prints was discr.ssed. The licensee stated a comparison of the installed system with the prints would be per-formed.
(Paragraph 5)
The inspectors expressed a desire for a sanple of the removed pipe C.
f or further evaluation by the NRC and stated that the licer.sce would be contacted at a later time.
(Paragraph 8)
Nondestructive testing including hydrostatic testing after repairs D.
was discussed.
It appeared that the minimum requirements of the" ASME Code could be met by utilizing nppropriate waivers.
(Report Details, Part II, Paragraph 3)
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rep 0RT DETAILS Part 1 Persons Contacted C. Larson, Plant Superintendent P. Krumpos, Quality Ansurance Engineer C. 'larmsen, Technical Service Metallurgist 1. Swedberg, Plant Engineering and Construction l
L. Hostvawsen, Minnesota State Code Inspector
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T. Lambert, NSC Manager of Plant Testing
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General The inspection was perforr.ed to review the licensee's activities i
pcrtinent to cracks detected in 4 inch recirculation pump discharEe
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by-pass lines and subsequent repairs, i
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Water Cheristry
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Water chenistry records from Uovember 3, 1974 through January 11, 1975
were exatined. No oxygen concentration information was available as l
primary ecolant oxygen testing is not required by the technical spec-ifications or contractual agieements with suppliers and vendors.
Results of some primary coolant samp?" " y""",'"'
le anal ses which the 11censec.
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claims are typical, are listad below
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Anlaysis Range Weekly Averare pH 6.2 - 7.8 6.2 - 7.4 Conductivity (umho/cm) 0.14 - 0.45 0.16 - 0.32 Chloride (ppb)
10 Two sets of primary coolant metallic analyses were examined for the period f rom November 1974. The following are the results of these analyses.
Filtrate (ppb)
Fe Ni Cu Ci 1.444 0.73 16.8 0.22 1.65 0.47 29.2 0.31 Crud (ppb)
1.15 0.35 1.43 0.51 1.34 0.12 1.77 0.23 3.
Original Pipe Material A review of the piping material analysis report revealed that the original material was 4 inch schedule 80 type 304 seamless pipe l
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Three of the suspect welds occurred in the
"A" loop and are designated RBAJ-6, KBAJ-7 and RBAJ-8. The fourth veld, which showed indications of the most severe crack propogation is designated RBBJ-10 and is located in the "B" loop.
Generally, the strip charts for January 1975 UT inspections reveal longer circumferential indications of cracking than were exhibited from the November, 1974 strip charts.
The November 1974 ntrip charts when compared to the current strip charts, showed minor indications which were not classified as being characteristic of crack indica-tions but were considered indicative of surface nonhomogeneities.
8.
Sample of Original pipe The inspector indicated during this inspection that the NRC might be interested in procuring a sample of the original piping for independent metallographic analyses.
Subsequent to the inspection, the licensee was contacted by telephone with a request to set aside a sample of one weld contain:ng a crack.
The licensee agreed to do this but indicated the sample night be cut and retained at the laboratory performing the metallographic work.
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rep 0RT DETAILS Part 11
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Prepared By:
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C. M. Erb (Date)
Reviewed By:
w [jg 3/h/h.i D. M. Hunnicutt, Chief
'(Da't e )
Construction and Engineering Support Branch
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1.
Purpose This inspection was made to review NDT test results on the two four-inch bypass line velds in the recirculation system and to ascertain corrective action for those areas where defective welds were identified.
2.
Persons Contacted buring This Inspection See Management Interview list.
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3.
Conclusion A study of the ultrasonic test results of January 1975, together with radiographic evidence, established that three velds, two in
Loop "A" and one in Loop "M",
contain cracks, emanating from the inside surface in the uc1d heat affected zone.
An examination of the UT results of Novenioer 1974 indicates that one, and poseibly two, of these welds containcd a linear indication which propagated to the larger size show in January 1975.
Sections of the bypass lines, containing the defective welds, will be removed and replaced with certified pipe and fitting materials as in the original installation.
The nonisolatabic end of the loop and part of the isolatable with ovend " elds will not be replaced.
Details The original repair plan called for usage of Type 304L replacement fittings.
It was pointed out to the licensee that usage of this material would constitute a design change, due to its lower allowable,
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as compared to Type 304 and Type 316. The itecnnue has since procured certifled Type 304 fittings from the Dresden cite which will be used.
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The following material certifications of replacement pipe and fittings are shown below:
Ouantity Grade Specification Tensile Yield Chemistry 2 Ells, 900 316 A403/A312 80,000 43,180 OK 9',4" Schedule 80s 30411 A312 86,300 43,100 OK Subsequent to thic inspection, the licensee initiated an investigatien to establish that this heat of 30411 steel is identical to Type 304 stainless steel. The licensee has qualj fied two welding procedurcs for the repair. One procedure utilizes an EB consumable insert in the
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root, while the other procedure uses the open butt method for the root.
In both cases, the root (two layers) of Tungsten Inert Gas (TIG) weld will be completed, using the Shielded Metal Arc Process (SMAU).
The construction NDT (Radjography and Penetrant Test) will be performed by qualified perronnel. The next step vill involve pressurization of the two repaired loops to-1,000 psi, f ollo'-:cd by an ul trascnic, base-line inspection to Procedure NVT-NC-1A.
This banc-line inspection will he performed by Nuclear Services Corporation- (NSC) who has done t.he previous UT inspections, except-for the original base-line inspections.
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UNiitD i.fATC$
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NUCl. EAR REGULATOhY COMMISSION OFFICE OF INSPECTION /uND EN10F. CEMENT
ntcion sia 799 ADO 5tVCLT ROAD CLI N L LLYN. 4LLINOl$ 60137
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IE Inspe/ tion Report No.
_050-263/75-02 A.
Transmittal Date
March 4, 1975
Distribution:
Distribution:
IE Chief, FS&EB IE Chief, FSLED IE:llQ (5)
IE:llQ (4)
DR Central Files L:D/D for Fuels L Materials Regulatory Standards (3)
DR Central Files Licensing (13)
IE Files 1E Files IE Chief, M6PPh L:D/D for Reactor Project E.
IE Inquiry Report No.
Transraittal Date
Distribution:
Distribution:
IE Chief, FS6EB IE Chief, FS6EB IE:HQ (5)
IE:HQ
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DR Cent ral Files DR Central Files Regulatory Standards (3)
IE Files Licensing (13)
IE Files C.
Incident Notification From:
(Licensee & Docket No. (or License No.)
Transt.i t tal Da t e
Distribution:
Distribution:
IE Chief, FS6EB IE Chief, FSLEE 1E:llQ (4)
IE:HQ (4)
Licensing (4)
L:D/D for Fuels & Materials DR Central Files DR Central Files IE Files IE Files
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