ML20039A535

Forwards Safety Evaluation Re Site Pipe Storage Practices. Carbon Steel Piping Is Acceptable.Issue Considered Closed

ML20039A535
Person / Time
Site:	Limerick
Issue date:	11/27/1981
From:	Schwencer A Office of Nuclear Reactor Regulation
To:	Keimig R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
NUDOCS 8112180034
Download: ML20039A535 (6)

Text

lbbdl'd h L So - H3 ' "M -

NOV 2 7 1981 h(j;rTlNhi ld@!

MEMORANDUM FOR: Richard Keimig, Chief g

Project Branch No. 2 DEC3 1981m

'j Division of Resident & Project Inspection i

IKE Region I

v. s.

rca FROM:

A. Schwencer, Chief fcff-N//>d. _k Licensing Branch No. 2 9

Division of Licensing, NRR

SUBJECT:

PIPE STORAGE PRACTICES AT LIMERICK GENERATING STATION

References:

1.

Memo from Carlson to Sevfrit, " Request for Transfer of Lead Respeasibility to NRR - Pipe Storage Practices at Limerick Generating Station (AITSfF12126Hl)" March 31, 1977.

2.

Memo from Pawlicki to Kniel, " Limerick Gmerating Station Unit Nos. 1 and 2, Pipe Storage Practices", May 23, 1977.

3.

Letter to Philadelphia Electric Company from NRR, " Pipe Storage Practices at the Limerick Generating Station",

July 14, 1977.

c.

4.

Letter to NRR from Philadelphia Electric Company, November 4, 1977.

5.

Itemo from Carlson to Reinmuth, " Pipe Storage Practices at Limerick Generating Station", December 5,1977.

6.

Memo from Seyfrit to Kniel, " Pipe Storage Practices at 4

Limerick Generating Station, Unit Nos.1 and 2, February 15, 1978.

7.

!!emo from Schwencer to Pawlicki, " Pipe Storage Practices at Limerick Generating Station", July 8,1981.

8.

Safety Evaluation Report, Philadelphia Electric Company, Limerick Generating Station, Units 1 and 2, Co rosion r

Engineering Section, Chemical Engineering Branch, " Site Pipe 5 torage Practice", November 19 -1981.

Reference 7 requested the corrosion engineering staff to evaluate the problems of the open item relative to carbon steel pipe storage as summarized in References 1-6.

omce +

8112180034 811127 sune.wc)

PDR ADOCK 05000352' A

PDR...

omp NHC FOW M 00 Sq NRCM Cm OFFICIAL RECORD COPY us m ini.- m uo

Richard Kefmig 2-Reference 8, enclosed, is that evaluation, and it indicates that on the basis of th'e low corrosion rates and inspections performed and witnessed by the NRC inspection, that the piping is ac.ceptable for use.

Based upon this we now consider this problem closed.

Original M %

A. Schwencer, Chief Licensing Branch No. 2 Divison of Licensing Office of Nuclear Reactor Regulation I

Enclosure:

Reference 8 Distribution:

Doel+et File 50-352/353 LB#2 File DEisenhut/RPurple RTedesco ASchwencer DCal kins EJordan GCollins VBenaroya SPawlicki 4

HConrad BTurovlin TEnthvan MService I&E (3)

NRC PDR Local PDR t/

m

)

OFOCE)...D L {.L B

.hb.*b0$

hb.* bh.* b......

RTedesco............. '......

sumue >

.D. C..a. l. ki.ns..:..phASchwen er 1.1../...2..s. jg1..1.1../...

/. 8.1...., 11/....A7../. 81 u

un>

.. ~.....

N NGC FORM 318 US80) NRCM ouo OFFICIAL RECORD COPY usa m m i.- m em

%f Od nl' os

..)

7

~~

SAFETY EVALUATION REPORT Philadelphia Electric Company Limerick Generating Station, Units 1 & 2 Corrosion Engineering Section Chemical. Engineering Branch Site Pipe Storage Practices Background Information By Amendment 17 to Appendix Ar the applicant requested permission to store carbon steel pipes outside wi.thout end caps.

The justification for supporting this amendment consisted of i

limited corrosion datar and was questioned by the Chief, Reattor Construction and Engineer,ing Support Granch, NRC: 1 in, March 1977 and has been an item of active controversy to date.

Evaluation In order to. evaluate the utility's pipe storage practices, we compared the susceptibility of capped and uncapped pipe to the corrosion process and the limiting factors of availability of

' oxygen and presence of aggressive speci'es in the aqueous

~

1 environment, such as chlorides.

Most pipe spool,s are not capped with a pressure tight seal but rather with. plastic and caps, which in nornal circumstances allow l

l water vapor intrusion (and eventual condensation) as. a result of I

the expansion and contraction cycle of the pipe on warm days

~

I

p.

~

through relatively cooler evening hours.

This condensed moisture would tend to accumulate and provide the aqueous solution ~

necessary to cause localized corrosion.

The oxygen supply would also be rejuvenated on the inside of the pipe spoo't during the contraction cycle and therefore available to sus'tain the corrosion process.

The condensed water may also contain dissolved ionic species which might further concentrate locally on the pipe surface and accelerate the corrosion rater by repeated evaporations and rewetting.

The licensee's alternative to capped pipe spool storage consists of three steps:

a) removal of sealant taper end capsi and dessicant from the pipe spoolsi h

b) location of all spools in storage such that they are free draining ~and not in contact with the ground, c) installation of rain hoods on open ends protruding upwardi where spools are. impossible to situate in storage without C

Leaving a " pocket" in which water may be trapped.

This method. of ' pipe storage would climinate the problem of standing water.

The canted angle of the pipe would also help to wash of f any water soluble contaninants on the pipe's inside

, surface during periods of rain.

60

Sither nethod of storage t.ould ::c e n to prbvide.a :, u f f i c i e n t-a r. iou n t of oxygen to promote'some corrosion, if the. steel is in contact with water, regardless of caps being present.

~

Hild steel is not generally susceptible to the same type of intergranular attack as are austenitic stainless stcels in the

~

presence of chlorides, sulfates, nitrates of carbonates except at el'evated temperatures._ These contaminants in various trace amounts are assumed to be the constituents of the rain in the Limerick area.

Since intergranular corrosion can 'bc safely ruled out, the primary concern would'then center on a thinning of the pipe wall thickness below StE Code required levels by either a general corrosion or perhaps a pitting attack..

Either of these processes would rel'y on oxygen availability and the chemistry of the^ aqueous medium, which in bo'th cases appear to be comparable.

The rates of neither are reliably h

r.casured by weight loss techniques,

\\

Telephone conversations with the Linerick site resident'NRC l

u...

inspector confirmed that the withdrawat of pipe from outdoor storage is governed by site procedures,which requi're a grit c

blasting op e r'a t i o n-an d a thorough cleanliness inspection prior to installation.

This inspection would include the rejection of pits, gouges, and other defects, which weutd encroach on the pipe's mininum code allowed uall thicknes~s.

The available test data show the overall wall thinning in

'l e

G e

cither case'to be relatively s m S i t.'

This together with the

~

utility's practice of grit blasting the pipe and then performing a visual inspection of the inside surface for cleanliness and defects prior to instattation gives assurance that the outsid'e storage of the pipe without.cnd caps will pose any serious hazards to the materials intended service not life.

conclusions on the basis of the low corrosion rates and the inspection

~

performed and witnessed by'the NRC inspectors, we conclude this piping is acceptable for the Limerick station.

e O

e A

.g C

9 k

e 1

-