ML053270500

Hairline Crack in IPEC Unit 2 Spent Fuel Pool South Wall, Revision 1

ML053270500
Person / Time
Site:	Indian Point
Issue date:	09/09/2005
From:	- No Known Affiliation
To:	Office of Nuclear Reactor Regulation
References
FOIA/PA-2005-0369
Download: ML053270500 (8)

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Background

IPEC is in the process of implementing dry cask storage capability for Unit 2.

This requires that the Fuel Storage Building (FSB) loading bay floor be removed i .' m-;c Z0-d 6S£6 S£L 146 GqSh AP). VlTA Aib!

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and replaced with a significantly more substantial structure. The original floor has been removed, and excavation of soil and rock in the loading bay is in progress. During removal of loose soil and rocks In the north area of the loading bay (along the SFPsouth wall), approximately horizontal cracks were exposed at an elevation of approximately 65 feet, and an approximately vertical crack above.

The cracks are very narrow (less than 1/64-inch wide). One of the cracks, on the west side of the south SFP wall, has moisture In and near it.

SFP wall structure In the area of the crackj A tX

• \ ,1L jThe cracks have been visually Inspected by an IPEC civil/structural engineer, and the IPEC Supervisor of (a Civil/Mechanical Engineering. The condition Istypical of cracking due to shrinkage during post-construction concrete curing. The moisture Inand around one of the cracks is very slight, essentially a film which Isnot dripping or beading.

The moisture has been analyzed and found to contain trace amounts of Cesium 134 and 137, Cobalt-60, and Boron. The Boron concentration Is about 6 to 15 times less than the concentration Inthe SFP, and the ratio of Cesium-1 34 to 137 indicate the activity is about 6 to 10 years old. The crack has calcium stains emanating from It,as Isexpected when moisture leaches through concrete, and no visual evidence of steel corrosion products (rust). Due to the thickness of the SFP wall, amount of steel reinforcement, and lack of evidence that the small amounts of moisture and boron have caused corrosion of the reinforcing rods, there Isreasonable assurance that the SFP wall is structurally sound and capable of performing it's Intended function.

Potential sources of moisture The moisture in and around the crack could be from one or a combination of several sources.

1. A leak, either active or In the past, through'the SFP stainless steel liner, Lland leach through the wall into the crack.

a. The Unit 2 SFP does not have a leak detection system. Usually such a system consists of a drain path[

- Sl(Unlt 3 has such a leak detection system). The Unit 23 j An active leak, depending on It's age and volume, could be determined when It develops by a change in frequency of pool water make-up and/or a change In pool boron concentration. A discussion with Unit 2 licensed operators SM %4 ACCa ACJ. bT__

indicated the frequency of make-up has not changed, other than that expected due to seasonal changes in pool water evaporation rate, and as a separate attachment to this paper, a trend graph of boron concentration in Unit 2 SFP is attached indicating no unexpected/unexplained loss of boron. However, due to the lack of a leak detection system, and the large volume of pool water normally lost due to evaporation, a small liner leak could go undetected.

b. Based on isotopic ratios and radionuclide type, the existence of radionuclides such as Cesium and Tritium In the moisture could provide an Indicator of whether there Is an active leak, or whether the moisture source could have been from a since-repaired liner leak. Soil and moisture samples are being collected and will be sent to a laboratory for analysis which can detect the presence of Tritium.

2. Contamination of the soil Inthe FSB loading bay,.above and adjacent to the moist crack, and subsequent entry of contaminated liquid into the crack due to hydraulic pressure from the loading bay side.

Historical Information

1. In the northeast area of the SFP stainless steel liner at about the 89 foot level, a small hole occurred during a 1990 pool re-racking project. The damage was discovered in 1992 when boron powder was found on the SFP east exterior wall. During subsequent radiological recovery and repair of the hole, outside soil adjacent to the SFP east wall was found to contain Antimony-1 24 and 125, and Cesium-137. Approximately 100 55-gallon barrels of soil, down to a.depth of eight feet below grade (72 foot level) required remediation. The leakage through the hole in the pool liner was estimated to have been 20-30 gallons per day, which was unnoticed due to the much large volume of normal evaporative loss from the pool.

2. The original loading bay floor had a drain system (see attached elevation sketch), above and adjacent to the area of the moist crack, which was piped through the wall separating the FSB loading bay and SFP heat exchanger room to a sump Inthe heat exchanger room. When the floor was removed In2004 for the dry cask storage modifications, the drain pipe was found to be cracked, and the wall penetration through which the drain pipe was Installed was found to be unsealed. Discussions with personnel who were working at Unit 2 at the time indicated that in years past, the level in the sump rose above the drain pipe penetration. This, along with the cracked pipe, resulted Incontamination of the soil beneath the floor.

Contamination of this soil, primarily in the northwest area of the loading

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• S. - e bay, was found and remediated during excavation in 2004 and 2005 for.

the dry cask storage project.

3. From 2003 through 2005, various activities associated with the dry cask storage project in the area above and adjacent to the crack required the use of water as a dust-inhibiting and cooling measure, which was allowed to drain into the FSB loading bay soil. These activities included core-boring, saw cutting of the original loading bay floor, and excavation, Six core-bore-samples,-to-a-depthnLgreateritharL20 feet. were taken in the FSB loading bay (four cores), and FSB access roadway (2 cores) In 2003 during the dry cask storage engineering study activities.

Industry operating experience In September 2002 the Salem nuclear plant found evidence of contaminated water leaking through a wall and onto the floor of the auxiliary building. This leak was found as a follow-up to unexpected shoe contaminations. There were other leaks through walls and penetrations that appeared to be originating from the Unit 1 SFP. It was determined that the tell-tale drains for the SFP were plugged with debris, so there was a build up of hydrostatic pressure between the liner and concrete wall. This caused the leakage to find alternative through-wall paths.

When these drains were cleaned, the leakage flowed to a collection system, essentially terminating the through wall leakage. The pool leakage was then identified via the drain system. This pool leakage occurred for an Indeterminate time.

Salem conducted sampling and analysis of the environment surrounding Unit 1 FSB, in a phased approach, to identify potential release of the water outside the building confines. On February 6, 2003, Salem found tritium (H-3) contamination In close proximity to the Unit 1 FSB. By pow the tell-tale drains were functioning, so the through wall leakage had stopped. Salem reviewed other spills that could have contributed to the tritium contamination.

Salem performed test core borings Invarious site locations and initially identified five areas with varying tritium contamination levels. 37 well locations were installed around the site to better characterize the extent of contamination, and 30 of the areas found some tritium contamination. There were no locations that found tritium Inunrestricted-access areas Action Plan The following actions are being implemented to aid in determining the source of moisture, potential amount and extent of related soil contamination, conclusions, and remediation/repair plan and schedule.

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1. The IPEC Manager of Dry Cask Stora'e (G. Schwartz, x668 as-overall responsibility for executing this plan, updatin i, nd keeping Nior management, NR , nd Unit 2 Shift M aer informed daily..; The IPEC Director of Special ProjefiD.

(r,x5521?* 6 o has responsibility for Health Physics Department) will assist.

anager of Wry Cask Storage) Issue Condition Report and submit Operability. Evaluation information to Shift Manager.

Complete. CR-IP2-2005-03557.

3. (Manager of Dry Cask Storage) Prepare Operational Decision Making Issue (ODMI). Target to Issue ODMI 9/13105.

4.. (Radiological Waste Department) Take radiological samples at damp crack, and take dirt smples from where excavation material was placed. Results (ND = None Detected):

Sample Date-time Location Type Co-60 uCi Cs-134 uCI Cs-137 uCi 9/1/05 10:00 AM N. Wall at leak Large Area Smear ND 3.03E-07 1.92E-03 9/1/0510:12 AM N. Wall at leak Large Area Smear ND 6.24E-04 4.64E-03 9/1/05 12:00 PM N. Wall at leak Large Area Smear ND ND 1.68E-03 9/1/05 2:00 PM N. Wall at leak Scraping of wall 2.22E-03 5.06E-03 8.07E-02 9/2/05 1:30 PM N. Wall at leak Large Area Smear ND ND 1.17E-03 912105 1:30 PM N. Wall at leak Large Area Smear ND ND 1.17E-03 Outside MOB Dirt on Hill area 917/05 1:00 PM1 Dirt ND ND 8.75E-08 Outside MOB Dirt on Hill area 9f7/05 1:00 PM2 Dirt ND ND ND Outside MOB Dirt on Hill area 9/7/05 1:00 PM3 Dirt ND ND 1.03E-07 Outside MOB Dirt on Hill area 97/05 1:00 PM4 Dirt ND ND 5.61 E-07 Outside MOB Dirt on Hill area 9/8/0510:00 AM4 Re-sample Dirt ND ND 2.18E-07

5. (Civil-structural Engineering) Determine rebar location in relation to cracks, using a rebar detection device. Completed 9 05. Rebar isc ..I;to cracks. & +

6. (Radiological Waste Department/Civil-structural Engineering) Hand-drill (small diameter bit) several inches into the SFP wall in the area of the moist crack and analyze drill-bit finds for contamination. Completed 9-7-05. Finds appeared to be damp in first several inches of depth, then appeared to be dry. Results:

Sample of Hole Drilled Co-60 Cs- I Cs-137 Iron Boron in North FSB Wall uCUqm 134uClgm uCl/gm ppm ppm Base line 11.74 ND ND ND 96 159 First 2' (q-2") of crack 10.7 8.31 E-05 2.65E-05 1.65E-03 628 . 72 5

Second 2" (2-4*) of crack 11.46 4.04E-05 1.39E-05 . 8.46E-04 640 56 Third 21 (4-6") of crack 11.75 1.02E-05 ND 1.27E-04 3285 28 Fourth 2" (6-8') of crack 11.79 ND ND 1.75E-05 60 226 If)

7. (Radiological Waste Department) Place a plastic covering over the moist crack to attempt to capture of a larger volume of 1

F) liquid for radiochemistry analysis. Plastic Installed 9-7-05 and left In place 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Collected approximately 2 mL of

'-4 liquid, which was insufficient for Tritium detection. Plastic will be reinstalled and left over weekend of 9/10 to IT 9/1105.

- 8. (Chemistry Department) Sample the soil beneath the area of the crack for H-3. Sample collected, sent off-site to laboratory for Tritium analysis 9/9/05 - results expected by 9/16/05 or earlier. Other analysis results:

Sample Date Location Co-60 uCrgm Cs-134 uCVigm Cs-137 uCVgm 9/6/200 5gainst North Wall below Leak Dirt 1.05E-0 3.98E-06. 2.92 E-04 9/6/200' I ft from N.Wall Below Leak Dirt 1.15E-06 ND 1.61 E-05 916/2005 2 ft from N.Wall Below Leak Dirt 2.42E-0 ND 5.07E-07 9/6/200 3 ft from N.Wall Below Leak Dirt ND ND 1.19E-07 Against North Wall below Leak 1 ft 9/8/200' depth Dirt 5.90E-06 3.54E-06 1.63E-04 1ft from N.Wall Below Leak 1ft M 9/8/200 depth Dirt U) 1.19E-06 1.82E-07 1.09E-05 ft from N.Wall Below Leak 1 ft 9/8/200! depth Dirt ND ND 9.44E-08

-4 gainst North Wall below Leak 2 ft 9/8/200! epth Dirt 1.38E-05 1.43E-05 6.OOE-04 ft from N.Wall Below Leak 2 ft 9/8/2005 epth Dirt ND ND ND 9.- (Chemistry Department) Scrape material from an unaffected area of the SFP wall and test for boron content. Used dry finds from drilling (see above table).

10. (Civil/structural Engineering) Determine the typical level of boron in clean concrete. Attempted, no information located as of 9-9-05.

11.(Civil/structural Engineering) Determine expected corrosion rates for steel reinforcing rods subjected to an environment containing boron. Calculation being performed using pH of SFP wall concrete based on samples taken, and using 6

baseline results published in Florida Power & Light Test report P522-1471 of 1987 (Long-term Concrete Rebar Test) regarding corrosion rates for rebar in a liquid-boron environment. Calculation targeted for completion 9 05.

12. (Licensing Department) Gather historical written records on SFP stainless steel liner damage and SFP sump overflows.

Liner damage Information recovered. Search for sump historical Information ongoing.

13. (Civil/structural Engineering) Arrange a ground-penetrating radar (GPR) inspection (or other methodology) of the crack to determine (ipossible) crack depth. GPR determined not feasible. Two 4-inch diameter coresL were taken 9-8-05 in the.area of the moist crack. One appeared to be dry on 9-8-05 and it is .

presumedtis was effected by boring bit heating. 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> later on 9-9-05 it was damp. The rebar exhibits normal surface oxidation.

14. (Chemistry Department) Determine if a Unit 2 Spent Fuel Pool Integrity Evaluation from Tritium Measurement, was performed, similar to that performed for Unit 3. Not performed for Unit 2. TBD whether to perform this, as It requires a lengthy period of data collection.

15.(Radiological Waste Department) Gather radiological results of test core borings accomplished for dry cask storage inside FSB loading bay (4) and In FSB loading bay access road in 2003. Target: 9-12-05 16.(Manager of Dry.Cask Storage) Bring in expert structural engineer from ABS Consulting with past experience in SFP leakage. Will arrive on site Monday 9-12-05

17. (Manager of Dry Cask Storage) Issue final version of this paper with conclusions and physical actions (as deemed necessary, such as repairs, test wells, etc.) and schedule. Target 9-23-05.

Summary as of 9/9105 Due to the thickness of the SFP wall, amount of steel reinforcement, and lack of evidence that the small amounts of moisture and boron have caused corrosion of the reinforcing rods, there is reasonable assurance that the SFP wall is structurally sound and capable of performing it's intended function.

The data collected so far is inconclusive. The next key event Is results of Tritium testing.

The Plant Manager, Engineering Director, Site Operations Manager, Unit 2 Operations Manager, and Shift Manager were fully briefed on 9-9-05.

Attachments (See initial issue of this paper dated 9-8-05 for first four items listed below, only core bore photos currently attached)

Elevation sketches (2)

Moist crack photograph Unit 2 SFP Boron graph Core bores photograph 7

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West Side Dry Cracks - 1/64' Width East Damrp Area

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