ML20106E236

Amended Final Deficiency Rept,Item 114 Re Possible Overpressurization of North RHR Hx.Initially Reported on 840124.No Evidence of Defects Caused by Overpressurization Found by Visual Evaluation,Ultrasonic & Boroscope Testing

ML20106E236
Person / Time
Site:	Fermi
Issue date:	10/08/1984
From:	Jens W DETROIT EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
114, EF2-70025, NUDOCS 8410290103
Download: ML20106E236 (3)

Text

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} /D Dehoit Edison RiEE!m>2e October 8, 1984 EF2-70025 Mr. J ame s G. Keppler Regional Administrator Region III U.

S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Reference:

(1)

Fermi 2 NRC Docket No. 50-341 (2) -Letter, D. A. Wells to J.

G.

Keppler, March 7, 1984, Q A-8 4- 0087 (3)

Letter, W. H. Jens to J.

G.

Keppler, September 5, 1984, EF2-68328

Subject:

Amended Report of 10CFR50. 55(e) Item 114 "Possible Overpressurization of North RHR Heat Exchanger" This letter amends Detroit Edison's final report of Item 114 "Possible Overpressurization of North RHR Heat Exchanger. "

Item 114 was originally reported as a potential deficiency on January 2 4, 1984 and was subsequently documented in References (2) and (3).

As described in Reference (3), on January 22, 1984, the north RHR heat exchanger may have been subjected to a fluid pressure on the shell side which exceeded the 450 psi maximum working pressure.

An investigation of the event by Detroit Edison Engineering included the following test, inspections and observations:

o On January 27, 1984, Detroit Edison requested General Electric, the vendor of the heat exchanger, to have Fromson Heat Transfer Ltd., the designer and the fabricator of the heat exchanger, review the capability of the heat exchanger to withstand the maximum postulated pressure of 1330 psig.

The N-4 nozzle area was singled out in the OCT 15 684 8410290103 841008 e

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Mr James G..Keppler i

' October 8,1984

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Fromson review:as the weakest portion of the shell.

Therefore,. insulation was removed from the aren and a visual examination of the painted area

~was conducted..There wasuno evidence of yielding.

(paint cracking) '..The paint-was then removed from designated areas and hardness readings were taken.

Thesecreadings, indicated.nothing which would

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indicate overstressing of the area.

Subsequently

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an ultrasonic preservice inspection of the N-4 nozzle'was performed by. Southwest:Research

. Institute personnel._ In addition'an ultrasonic surface. wave examination was conducted by Detroit

' Edison's' Engineering Research laboratory.

These tests indicated no surface connected defects.' The Fromson-report also indicated that if the heat ex-

. changer had been overpressurized to the maximum 2*

postulated value,-damage may have: occurred in the channel on the cooling water; side..Specifically, the pass _ partition plate.might'be deformed by the flexing of tdue tube sheet.

Therefore, this area was examined by means of a boroscope which'was-inserted through a relief' valve connection and -

through a drain' connection. fThere was no indi-cation that the passcpartition' plate was deformed..

o To. check for. tube damage, Detroit; Edison deter-mined that-there was no leakage and no reduction in flow.- Tube leakage.was. checked by_ performing a hydrostatic test of the shelli side of the north RHR heat exchanger at the. maximum-working pressure

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_.ofl 450 psi.

There wasino; indication of:any!1eak-

. age either.at.the flange area or?from the shell.

b side _through the tdhes.

To~ check'for a reduction

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in flow.- differential pressure measurements were taken across. the -tube side of both RHR heat-ex-changers.under-actual flow. conditions.

These tests revealed that the differential ~ pressure drop

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- across the tube side of both RHR heat exchangers Lwere comparable and within design limits indi-cating that there is no reduction-in flow through the north RHR heat' exchanger as a.. result of this incident.

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v Mr.-James G. Keppler

' October 8,198 4 '

EF2-7 002 5 Page 3 (Although Detroit Edison can not. conclusively state that the north RHR heat exchanger was not overpressurized,.idue investigation and; analysis described above demonstrate that the heat exchanger meets design requirements and.is therefore acceptable for its intended function.

If you have questions concerning this matter, please contact Mr. Lewis P.

Bregni, (313) 586-5083.

Sincere ly,

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Mr.

P. M. Byron Mr.

R. C. DeYoung Mr.

R. C. Knop u.

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