Text

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit Report, 1487203-R-001, Revision 0
	ML103481101
Person / Time
Site:	Indian Point
Issue date:	09/30/2005
From:	Bruck P; ABS Consulting
To:	; Entergy Nuclear Northeast, Office of Information Services
References
	FOIA/PA-2011-0026
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Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit Table Of Revisions Revision No.

Description of Revision Date 0

Original Issue 09/30/05 i 1 11 -

i I

Report No. 1487203-R-OO1, Rev. 0 Page 3 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit APPROVAL COVER SHEET TITLE Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit REPORT No.

1487203-R-001 CLIENT Entergy Nuclear Northeast - Indian Point Energy Center Unit 2 PROJECT No.

1487203

'4-ABS Consulting Report No. 1487203-R-001, Rev. 0 Page + pr &3.

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit TABLE OF CONTENTS

1.0 INTRODUCTION

7 1.1.

Scope & Objective.......

7 1.2.

Background......................................................................................................

7 2.0 ASSUMPTIONS AND DESIGN INPUTS.............................................................

10 3.0 METHOD OF EVALUATION & ACCEPTANCE CRITERIA.................................

11 3.1.

Method of Evaluation.......................................................................................

11 3.2.

Acceptance Criteria.........................................................................................

14 4.0 EVALUATION......................................................................................................

15 4.1.

Chemical Attack on Concrete and Aggregates...............................................

15 4.2.

Chemical Attack on Steel..................................................

15 4.3.

Corrosion Evaluation.......................................................................................

17

5.0 CONCLUSION

S.................. :.......... n....................................................................

20

6.0 REFERENCES

22 ATTACHMENT A................................................................................................................

35 Boric Acid Corrosion Test Report (Ref. 12) 35 ATTACHMENT B...................................................................

50 Structural Assessment of W est W all.....................................

............................................. 50 ATTACHMENT C........................................................................................................

85 Record of Conversation.................................................................................................

85 ATTACHMENT D..............................................................................................................

88 NQP-02 Exhibit 1 Review Guidelines...........................................................................

88 R/6j,.4.No. 148 P7 g 53-R-oe 8

Page 5 of 88

Study of Potential Concrete Reinforcement-Corrosion on the Structural Integrity of the Spent Fuel Pit LIST OF FIGURES Figure 1: Plan View Sketch of SFP & Adjacent Structures (NTS).................................

24 Figure 2: FHB Looking North.........................................................................................

25 Figure 3: FHB Looking East...........................................................................

26 Figure 4: Crack Like Indication & Moist Region - Approx. El. 64 ft...............................

27 Figure 5: Identified Indication in West Wall (Lkg. East from Pipe Pen)..........................

28 Figure 6: Photographs of Reinforcement in South Wall Exposed by Core Boring at Crack Like Indication - Upper Moist Region......................................................................

29 Figure 7: Concrete Rebar Corrosion Mechanism (Results in Concrete Spalling)........... 30 Figure 8: Rebar Corrosion Rate (Ref. 11.C)..................................................................

31 List of Tables Table 1: Chemical Composition of Core Bores Taken at Identified Indication (Ref. 10). 32 Table 2: Assessment of Wall Strength With Rebar Corrosion....................................

33 uns Repoft-Nc.-T4_87203-R-Ol,_ Rev.-O"'

Page 6 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit

1.0 INTRODUCTION

During excavation work associated with the Independent Spent Fuel Storage Installation (ISFSI) project a horizontal crack was identified in the south wall of the spent fuel pit, approximately 10 feet up from the base slab at El. 64 ft.

At one location along this horizontal crack a moist region of concrete has been identified with dimensions of approximately 20" wide by 20" high. An additional region approximately 4 ft below the first indication was also identified on the wall. Potential exists that these identified moist regions are associated with a leakage path of spent fuel pool water inventory through the Spent Fuel Pit (SFP).

1.1. Scope & Objective The scope of this report is to address the structural integrity of the IP2 spent fuel pit within the Fuel Storage Building (FSBY with consideration of potential chemical attack on concrete, aggregate and rebar, and concrete rebar reinforcing steel degradation from corrosion.

The objective of the report is to demonstrate the spent fuel pit remains structurally sound and operable in-terms of performing its safety related function of containing the spent fuel pool water inventory.

1.2. Background The Spent Fuel Pit is a reinforced concrete structure located in the Fuel Storage Building. The SFP consist of %" stainless steel lined reinforced concrete walls and base slab. The SFP contains spent fuel racks, which are resting on the floor of the pit, and filled with borated water.

The Unit 2 Containment, the Fan House, and the Primary Auxiliary Building bound the FSB, see Figure 1. The SFP has walls of 4'-0" and 6'-3" thick with a 3'-0" thick base mat founded on rock at elevation 51'-7", Figure 2 and Figure 3.

A prior leak was identified in the stainless steel liner during 1992. In support of remedial action a report was prepared (Ref. 15) investigating concrete and reinforcement degradation.

As part of this effort a number of concrete cores were drilled to a depth of 5' - 0" and extracted from the 6' - 3" thick upper portion of the wall.

These cores were petrographically examined and cylinders were tested.

Additionally, "view windows" were cut into the.concrete to enable the outer layer of reinforcement steel to be examined for evidence of corrosion damage.

The Ref. 15 report concluded the concrete strength exceeded design requirements. The concrete was found to be durable, with carbonation occurring at the examined area to a distance of less than 1" - thus enabling the alkalinity of the concrete to protect the rebar.

Visual examination of the exposed rebar identified only local and minor corrosion. Where corrosion had occurred, it was

" :eji.,*.,1482.... OOPag ev. 0 Page 7 of88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit as a result of exposure through a concrete spall, with subsequent chloride attack and not a consequence of boric acid attack.

1.2.1. Water Chemistry A review of the technical specification (Ref. 9), and discussions with plant operations personnel (Ref. 10), determined that the following conditions are typically found within the SFP.

Temperature

=

40 to 140 degrees F Chlorides:

1.5 ppm pH:

=

4.0 to 8.0, typically 4.8 Conductivity 20 ps/cm Boric Acid Concentration

=

2,000 ppm, no greater than 2,400 ppm 1.2.2. Materials The specified compression strength of concrete at 28 days, fc, used in the construction of the SFP is 3,000 psi, Ref. 1. The reinforcing bars used are in accordance with ASTM A-432 standard specification (Ref. 1). The yield strength, fy, for this material is 60,000 psi.

The allowable stress is 24,000 psi in accordance with ACI 318-63, Ref. 11.A. The Spent Fuel Pit Liner is made of 1/4" stainless steel plate, ASTM A240 TP-304 (Ref. 3).

1.2.3. Fuel Storage Building Foundation Based on information within Ref. 5 the Indian Point Unit 2 Power Plant is founded upon a hard, strong, and dense recrystallized carbonate rock of Cambro-Ordovician age. The rock is predominantly thick-bedded dolomite with a few thin shaley intervals. The strata strike in a northeasterly direction and dip from 450 to 650 to the southeast.

The structure is embedded in the rock on the east side, and the grade elevation is 79'-0" on the east, and north sides. The Fan House structure abuts the west and portions of the south side of the FSB.

1.2.4. As-found Crack'Observations The identified crack is located on the outside of the south wall of the spent fuel pit, approximately 10 feet up from the base slab at El. 64 ft.

At one location (near the west end)*along this horizontal crack a moist region of concrete has been identified with dimensions of approximately 20" wide by 20" high. The identified crack is of tight configuration, no greater than a 1/32" inch wide at the surface, with no rust staining or other tell-tail signs of corrosion products being leached from the concrete through this crack, Figure 4.

Initial inspection of the

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Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit crack by Entergy Civil Engineers determined the as-found crack is likely from original construction, either associated from a construction pour or heat of hydration thermal cracking.

The observed crack does not appear to be the design "cold-joint" due to its wavy appearance and the drawing location for the cold joint is approximately 11'-0" above this location at El. 75 ft., Ref. 2.

Examination of the adjacent west wall of the SFP in this southwest corner of the pit is observable from the Piping Penetration region located within the Fan House. Observations in this location identified a similar indication, Figure 5.

Two 4" diameter core-bores were drilled into the wall at the location of the observed indication exposing the rebar. Exposed rebar were observed to be in excellent condition with no indication of wall loss or corrosion products present, Figure 6.

Subsequent excavation below the indication at El. 64' identified as similar indication, approximately four feet lower.

AFu~~i oNo.

P 148 72-oR-fO1 Rev.80 Page 9 ofO8

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit 2.0 ASSUMPTIONS AND DESIGN INPUTS Design inputs to this problem are clearly listed by reference in Section 6.0. Key input values are summarized below:

1. The pool water composition, including boron concentration is based on values provided in Reference 9, and listed in Section 1.2.1. The typical values of pool water pH and upper limit of boron concentration were based on telecom, Ref. 10

2. The design strength of the wall is based on general notes of drawing 9321-1026, Ref. 1.

3. Pool water loading to the south wall of the SFP under seismic excitation used to develop moments in the wall were extracted from the original design basis calculation, Ref. 4 and updated for finite element analysis in the Ref. 16 evaluation. The basis for the methodology used in Ref. 4, although not explicitly stated, is based on a methodology presented in TID-7024, Ref. 21.

4. The basis for the corrosion rate of reinforcing steel subjected to water leakage containing a boron concentration is from actual test data, Ref. 12 and from measured data of carbon material submerged in water containing similar concentrations of boron at the IPEC site, Ref. 22.

5. The assessment performed assumes any potential rebar corrosion that may occur in the future will be limited to local areas where leakage is presently observed. Such areas may in the future be subjected to local concrete spalling, but the surrounding regions - where no leakage is occurring - will remain sound with the rebar being passivated by the alkalinity of the concrete.

I --

M Opniauffl 4ý11.W -W*1 Report No. 1487203-R-001, Rev. 0 Page 10 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit 3.0 METHOD OF EVALUATION & ACCEPTANCE CRITERIA 3.1. Method of Evaluation The spent fuel pit is evaluated to determine its ability to perform its safety function of maintaining the spent fuel pool water inventory under all design bases operating conditions, with consideration of potential concrete rebar degradation as a result of corrosion.

Concrete, as a structural material is strong when subjected to loading which places the material under compressive forces, but weak when subjected to loading which places the material under tensile forces.

As a result, steel-reinforcing rods "rebar" are added to the concrete to carry the tensile forces. In this manner, reinforced concrete structures can be designed to withstand loading which subjects the material to both compressive and tensile forces. The amount of steel reinforcement added to a concrete section is dependant upon the shape of the section and the amount of tensile forces that are required to be carried by the section. If the rebar should degrade through corrosion, the diameter of the reinforcing bars decreases with a corresponding decrease in the area of steel reinforcement within the degraded concrete section. As a result, the concrete section's capability to withstand tensile forces is also reduced. It is noteworthy that in the presence of aggressive ions, pitting attack of rebar may occur which can yield a loss in strength without the general deterioration in cross section.

This evaluation is performed by estimating the likely degradation due to corrosion that could have or may occur in the future, of the concrete rebar, as a result of fuel pool leakage.

As a result of hydration reactions of cement, the pore solutions of concrete are alkaline, with pH values typically in the range 12.5 -

13.6, Ref. 11.B.

Under such alkaline conditions, reinforcing steel tends to passivate and display negligible corrosion rates.

Concrete is a semi-porous material and in the absence of a protective lining, a concrete structure containing water will saturate. With the assumption that the existing lining has developed a leak, would enable pool inventory to accumulate under static pressure between the concrete wall and the liner. Subject to the permeability of the mix, and geometry of water head, it is conceivable that some continual permeation of retained water is occurring. The continual permeation may in part be responsible for the moist region identified at the horizontal crack on the south wall.

In consideration of the historical nature of the stored water, it is possible that the lower pHs associated with the boration may have served to neutralize some of the alkalinity. Initially this would have been a surface effect, however, with short circuit paths (cracks) in the concrete and subject to the degree of permeability this effect could have occurred beyond the surface (subject to the pH n-R ep o r N o.4*N.7 P03-a e 1 R f 8 0 Page I of 68

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit experienced). It is considered that there may have been some surface attack (or etching) of the cement paste and indeed possibly some short circuit deterioration.

In the case of voluminous corrosion products, internal stresses are generated and there is subsequent cracking and spalling of the concrete.

This is represented schematically in Figure 7.

Clearly the reinforcing, steel is more vulnerable to further corrosion damage after the protective concrete cover is compromised in this manner.

The strength of the concrete pools can be determined with consideration of rebar degradation relative to their original strength (i.e. with no rebar degradation) based on the estimated loss of rebar diameter.

Once the strength of the concrete is determined with consideration of rebar degradation, a comparison can be made to the critically stressed regions of the fuel pool. The loss in rebar area due to corrosion degradation will directly affect the strength of the concrete section.

The spent fuel pit wall was originally evaluated in the Ref. 4 design basis calculation. In support of wall degradation assessments performed in support of the liner leak discovered in the 1992 timeframe, an additional assessment was performed, Ref. 16. The Ref. 16 assessment was focused on the then believed degradation occurring in the upper portion of the wall (i.e. where the wall thickness is 6' -

3").

As was demonstrated in the LPI report, Ref. 15, such degradation had not occurred, and both the concrete strength of the wall, and the condition of the rebar within the wall were found to exceed or be consistent with design conditions'.

As can be seen through examination of the presently exposed south wall of the SFP, no areas of concrete spalling are visible.

,Corrosion attack of the rebar as was shown in the spalled regions in the upper portion of the wall investigated in 1992 are highly unlikely. Examination of rebar at the crack like indication, Figure 6, supports this position with no indication of corrosion occurring at this time.

To more accurately evaluate the wall strength considering rebar degradation in the portion of the south wall where moisture has been observed, a computer model of the south wall was developed using the finite element computer program SAP2000.

The SAP2000 version 7.4 computer code (Ref. 17) is verified and certified for use on safety related projects in accordance with the ABS Consulting Nuclear Quality Assurance Manual (NQAM) (Ref. 18) and

'The limited rebar corrosion that was identified in the Ref. 15 LPI report was attributed to exposure in discrete regions as a result of inadequate concrete cover, long-term exposure to moisture, carbon-dioxide, and condensation of chloride laden air on the outer surface of the exposed pool walls. Since such indications are not present on the south wall, and the wall is normally covered by the soil, such issues are presently not of concern for the evaluation of the south wall.

Report No. 1487203-R-001, Rev. 0 Page 12 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit procedure NQP-03 (Ref. 19).

Documentation of the program verification is contained in Ref. 20.

Loading for this model consisted of self-weight, hydrostatic loading from the enclosed spent fuel pool water, and seismic excitation of the wall and enclosed water utilized loading developed in the Ref. 4 and 16 calculations, based on methodology from TID-7024 (Ref. 21).

Load combinations evaluated were as per Ref. 16 being:

o D+H+Es o

1.5 (D + H) o 1.25 (D + H + Eo)

Where:

D

- Self-weight H

- Hydrostatic load on wall Eo

- Excitation of wall and water content to OBE earthquake Es

- Excitation of wall and water content to SSE earthquake OBE - Operational Basis Earthquake, 0.1g horizontal ground acceleration per Ref. 5 SSE - Safe Shutdown Earthquake, 0.15g horizontal ground acceleration per Ref. 5 Results were extracted from the model for the corrosion evaluation only in the lower west region of the south wall where moisture has been observed. The Ref.

4 and Ref. 16 calculations provided the qualification basis for all other regions of the pool walls.

The model of the south wall, applied loading and results obtained are outlined in Attachment B.

The critically stressed regions were evaluated to determine moment capability and resulting Interaction Ratios, (IR). The sections where potential leakage is occurring are then reevaluated to determine the required area of steel to carry axial tension and bending moment. Comparing the required area of steel (A's-required) to the area of steel provided.(A's-provided) enables the amount of acceptable reinforcing bar wall loss that can occur to be determined.

Using a conservatively derived corrosion rate per year (refer to Section 4.2), the number of years of acceptable service for the pool from the onset of corrosion can be determined.

The general consensus for service life prediction of reinforced. concrete structures, (Ref. 23, 24, and 25 for example), are concerned with rebar corrosion eventually yielding to concrete spalling as a result of expansion of the corrosion products, Figure 7. For the cases evaluated, such potential future spalling of the concrete will not result in loss of rebar strength (other than loss of rebar area as Report No. 1487203-R-001,- -Rev. 0 Page 13 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit outlined above) or loss of the ability of the general region to carry load. Local to the spall region loss of rebar/concrete bond would be expected. However this is a local effect, which closely approximates a hole cut into the wall, where the surrounding material stresses would increase to carry this load.

Loss of continuity of the rebar across such a spall would not be expected unless the bar was to fail from overload or corrosion wall loss. To ensure such cases are adequately and conservatively addressed, a region of the wall near the identified indication area are assessed considering loss of two reinforcing bars in both the horizontal and vertical directions. This case would envelop local failure of bars within the identified indication region.

Additionally, the SAP model of the wall was evaluated considering a cracked case, whereby the wall model continuity was broken in the horizontal direction crack at the El. 64 ft. indication.

Such a case approximates loss of vertical reinforcement continuity in the wall, and or loss of horizontal reinforcement along the modeled crack.

3.2. Acceptance Criteria The acceptance criteria for this evaluation is defined as the new calculated Interaction Ratio (IR) of the degraded rebar section being less than or equal to unity. Thus for calculated Interaction Ratios the acceptance criteria is shown as follows:

Interaction Ratio Acceptance Criteria = IR -* 1.0

'0't~

i

-Rejbrf No. 1487203-R.,01, Rev. 0 Page 14 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit 4.0 EVALUATION This section of the report performs the evaluation of the fuel pool to determine effects of chemical attack on concrete, aggregate and rebar, and potential rebar reinforcement corrosion.

Reviewing the water chemistry and comparing the known concentration of chemicals to available data on concrete performance forms the basis for evaluation of the effects of chemical attack.

For the evaluation of rebar degradation, it is required to estimate the resulting degradation of the reinforcing bars as a result of corrosion. The wall sections are evaluated to determine accurate axial tension and moment occurring in the lower west region of the south wall, the area where moisture on the surface of the concrete has been observed.

Using the approach outlined in Section 3.1, the required areas of reinforcement are determined, enabling the required reinforcing bar diameter to be determined. The remaining life of the pool can be determined based on reduction of the reinforcing bar diameter from the original diameter to the required diameter using the conservatively estimated corrosion rate per year.

4.1. Chemical Attack on Concrete and Aggregates The potential make-up of sampled water from leaking SFP is as shown in. Section 1.2.1. The measured concentrations of chlorides (CL) from potential pool water flowing through the concrete crack(s) are considered as negligible. The levels of boron within the pools are considered as consistent with levels used by another licensee during testing for effects of boron.

Based on studies performed by another licensee (Ref. 12) boration affects at concentration levels of 2000 ppm had negligible adverse effect on concrete. This conclusion is supported by the core testing performed in the LPI report (Ref. 15), where concrete compression tests of the SFP cores tested with a mean strength of 4,300 psi and standard deviation of 980 psi, exceeding design values of 3,000 psi.

In the text.by Kuenning (Ref. 13) it is noted that borates will not be detrimental.

The evidence available is based on Portland Cement Association (PCA) exposures of small mortar specimens at room temperature.

4.2. Chemical Attack on Steel The only possible attack on the rebar is associated with low pH or boric acid attack. Steel exposed to a pH of less than 5.3 for a period of time may exhibit some corrosion. Based on ACI 222R-01 (Ref. 11.B), a significant escalation of the corrosion rate in iron does not occur until a pH level drop below 3.0. No change in corrosion rate is noted between a pH of 4.0 and 5.3. Based on ACI 222R-01, corrosion can occur at pH levels possible within the pools. Research work outlined in Ref. 11.C determined corrosion rate is related to the water-

................N.1 4 8 7 2 O 3R.1, R e v...

Page 15 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit cement ratio. Corrosion rate increases with increased water-cement ratio. Using the Tafel Plot Technique, determined by Ref. 11..B as most applicable, would yield corrosion rates of approximately 2 mpy for a bounding Water-Cement ratio 2 (a value of 0.55 was used), Figure 8. Using the enveloping method at this W/C ratio, a conservative bounding corrosion rate is determined as 2 mpy value, which is converted as follows:

1 mpy = 0.001 in/yr Thus 2 mpy = 2 x 0.001= 0.002 in/yr, or 51 pm/yr.

Tests of rebar corrosion in concrete that has been pre-cracked, exposing the bar to the environment is as outlined in work performed by Tremper (Ref. 8). The rebar within the SFP are not exposed to a wetting and drying environment, since the water level remains constant.

Additionally, the water within the SFP is demineralized and oxygen content is extremely low.

Thus use of such a value can be considered as conservative3. For the region of the wall being investigated use of such. a corrosion rate would be conservative based on the core bores taken on the wall, where measured pH values (Table 1), indicate carbonation of the concrete has not occurred down to the reinforcement layer. No spalls are evident and no rust staining is visible on the wall, indicating the normal concrete alkaline nature continues to passivate the steel. This is further supported by the observed condition of the steel at this location Figure 6, which shows no indication of degradation.

Considering the testing performed in Ref. 12 and presented in Attachment A, an exposed rebar subjected to a drip test consisting of 300 drops,*per minute in a boric acid concentration of 2370 ppm and exposed for eight years had negligible effect on corrosion loss to the bar. A similar'test where the bar was submerged in the boric acid resulted in a final bar diameter of 1.09 in after the test period.

Considering the test bar as a #9 bars with a diameter of 1.128 in, Ref. 14, the resulting corrosion rate is (1.128in - 1.09 in/8 years) = 0.0047 in/year. This value exceeds the 0.002 in/year based on normal corrosion environment.

However, for a bar to reach the state of the test sample and be completely submerged in the boric acid would require breakdown of the passive film protecting the bar.

ABS Consulting during 2003 performed an assessment of as-found conditions within the IPEC - Unit 1 east spent fuel pool, Ref. 22. Within this pool, portions 2 A water cement ratio of 0.55 bounds the water cement ratio used in the concrete for the pools. This is supported by the LPI report (Ref. 15), which determined W/C ratios of 0.38 to 0.45.

3 The LPI report identified rebar on the outside of the wall at spalled locations that had been exposed and attacked by chlorides. These bars were reduced in size from 1.0 in dia. to 0.85 in dia. Thus wall loss = (1.0-0.85) = 0.15 in.

Period of corrosion is 1972 to 1992 = 20 years. Thus measured corrosion rate is 0.15"/20 yrs = 0.008"/year. This value was concluded as a result of localized chlorides attack, and not indicative of the environment to be found either in the wall or exterior to the south wall.

7AM S

Report No. 1487203-R-O01, Rev. 0 Page 16of88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit of the spent fuel pool rack are fabricated of A36 carbon steel and had been subjected to a borated water environment (approximately 2000 ppm boron solution) for a period from 1962 until 2003. Examination of this steel determined a bounding (2 sigma deviation) wall loss of 1.01% per year. For the 0.456 in nominal thickness of the steel examined this resulted in a corrosion rate of 0.005 in/yr. It should be noted this steel was submerged in the borated water, and not protected by concrete alkalinity as would be expected with a reinforcing bar in the concrete wall.

It is additionally noteworthy that concrete, which is permanently saturated, will be exposed to much lower oxygen contents. In such situations the passive film may not be stable and environment can be termed as one which is 'low-potential active,' i.e. the steel is not protected by passivity but the thermodynamics are such that corrosion rates are minimal - the oxygen reduction reaction is stifled in neutral solutions. The low corrosion rates are further substantiated by the very low conductivity of the storage water. Higher conductivities promote accelerated reaction rates.

Based on the above discussion and assessment, it is concluded use of a corrosion rate of 0.005 in/year would be conservative and bounding of any likely conditions in the west portion of the south wall of the IPEC Unit 2 SFP.

4.3. Corrosion Evaluation An evaluation of the south wall of the SPF was performed in Attachment B to derive forces and moments in the lower west region of the wall. This is the region where surface moisture has been observed, and the wall is evaluated to quantify the potential effect of pool leakage on its capability.

The assessment is performed consistent with the Ref. 4 design basis and Ref. 16 evaluations based on ACI 318-63 (Ref. 11.A) requirements.

Minimum reinforcement requirements for a reinforced concrete wall with deformed shape reinforcement of 60,000 psi yield strength are 0.0015 to 0.0025, Ref. 11.A, Para.2202. The wall thickness in the area of assessment is 4 ft. thick (48 in). The resulting required minimum steel reinforcing area is:

Min. Required Area (per code requirements - (See footnote4)):

= 12in wide x 48in deep x 0.0015 = 0.864 in2 vertical.

= 12 in wide x 48in deep x 0.0025 1.44 in2 horizontal 4 ACI 318-63 permits lower than code minimum, provided sufficient steel is provided for strength requirements, Ref. I L.A, Para.2201. Note the state of stress in the wall is generally less than the tensile capacity of the concrete (approx. 411 psi) - per assessment in Ref. 16. Concrete is not expected to crack under service conditions. The level of stress in the reinforcing bars are very low.

Report No. 1487203-R-001, Rev. 0 Page 17 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit The wall is evaluated as shown in Table 2 to derive the Years of Service (YoS) to be expected with corrosion occurring. The assessment is based on the following equations.

Ultimate Axial Capacity, Nu. For simplicity of the assessment the steel provided in the compression face is relied on to carry the axial load, and the steel in the tension face is relied on to carry the moment, thus:

Nu = p x A"s x fy...........................................................

Eqn. 4-1 Ultimate Moment Capacity, Mu:

Mu = (p x A's x fy [d - (A's x fy)/(2 x 0.85 x fc x b)]................ Eqn. 4-2 Interaction Ratio, IR1, IR2:

IR I = N /N u.................................................................. E qn. 4-3 IR2 = M/Mu..................................

Eqn. 4-4 Note, this is based on A's and A"s being used for moment and tension separately.

Required A"s for Axial Capacity, A"s reqd:

A"s reqd = N/ (p x fy).....................................................

Eqn. 4-5 Required A's for Moment Capacity, A's reqd:

M = (p x (A's reqd) x fy [d - (A's reqd x fy)I(2 x 0.85 x f'c x b)].... Eqn. 4-6 Determine A's reqd for equality.

Required Bar Diameter, Dia-reqd:

Dia-t-reqd = [4 x (A's reqd x 1/Area Adjustment)/!rr] 05......... Eqn. 4-7a Dia-c-reqd = [4 x (A"s reqd x 1/Area Adjustment)/! r] 0-5....... Eqn. 4-7b Wall Loss to derive A required, WL:

W L-t-face = (Dia-t - Dia-t-reqd)........................................

Eqn. 4-8a W L-c-face = (Dia-c - Dia-c-reqd)......................................

Eqn. 4-8b RepofftNo. 1487203-R-001, Rev. 0.

Page 18 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit Years of Remaining Service, YoS:

YoS t-face = W L-t-face/CR.............................................

Eqn. 4-9a YoS c-face = WL-c-face/CR......................

Eqn. 4-9b YoS min = minimum (YoS t-face, YoS c-face)..................... Eqn. 4-9c Where:

Nu

= Ultimate Axial capacity, kips/ft Mu

= Ultimate Moment Capacity, kips-ft/ft

,(p

= Capacity Reduction Factor A's

= Area of steel provided in tension face of wall, in2 A"s

= Area of steel provided in compression face'of wall, in2 d

= Depth to ctr of steel bar for moment evaluation, in b

= Unit width of section being evaluated = 12 in fc

= Compressive strength of concrete = 3,000 psi fy

= Yield strength of steel reinforcement = 60,000 psi.

YoS

= Years of service remaining.

CR

= Corrosion Rate The results of the corrosion assessment are presented in Table 2. This derived a Years of Service (YoS) life as 26 years.

This value was derived, based on corrosion of rebar down to code specified minimum values.

Using actual reinforcing area required to carry the loads for the section evaluated, the YoS values were calculated to be at least the forty-year design life of the structure.

As outlined in Attachment B, the wall was also evaluated with consideration of local spalling of concrete, together with an analytical case of loss of vertical continuity in the wall at the El. 64 ft. crack indication.

Both additional assessments demonstrated the ability of the wall to safely carry load following rebar degradation through local rebar corrosion and subsequent local regions of concrete spalling.

Report No. 1487203-R-001, Rev. 0 Page 19 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit

5.0 CONCLUSION

S This assessment is prepared as a study to address a potential concern relative to leakage of inventory from the Indian Point Unit 2 spent fuel pool, contained within the Fuel Storage Building (FSB). During excavation work associated with the ISFSI project a horizontal crack was identified in the south wall of the fuel pool, approximately 10 feet up from the base slab at El. 64 ft.

At one location along this horizontal crack a moist region of concrete has been identified with dimensions of approximately 20" wide by 20" high. Further excavation identified a similar indication approximately 4 feet below the first identified indication.

Potential exists that these identified moist regions are associated with a leakage path of spent fuel pool water inventory through the wall of the spent fuel pit. Past leakage in the IP2 pool, identified as a liner leak, was repaired in the 1992 timeframe. The presently identified crack is of tight configuration, no greater than a 1/32" inch wide at the surface, with no rust staining, concrete spalls or other tell-tail signs of corrosion products being leached from the concrete through this crack.

The primary structural concern with leakage from the Spent Fuel Pit (SFP) is the effect on the reinforced concrete structure, which forms the pool walls and floor. This is a Class I structure as specified within the Unit 2 UFSAR.

An evaluation was performed to assess the effects of pool leakage on the spent fuel pit structure. ACI 222R-01, "Corrosion of Metals in Concrete" indicates that a significant escalation of the corrosion rate in iron does not occur until pH values drop below a value of 3.0 at room temperature. For pH between 4.0 and 5.3 the corrosion rate is approximately 2 mils/year. Another licensee previously evaluated the effects of similar concentrations of borated water to that in the IP2 pool on rebar corrosion. The corrosion rate over a period of time for a bar exposed and submerged in the borated water solution was determined as 5 mils/year.

This corrosion rate is supported. by examination of carbon steel components submerged in the IPEC Unit 1 pools subjected to similar levels of boric acid concentration.

Based on no currently measured loss of inventory from the pool, the rate of potential seepage through this crack would be very small, such that borated water saturation of the rebar is unlikely, and the use of corrosion rates of 5 mils/year would.be conservative and bound actual conditions.

The original structural calculations for the SFP determined required steel reinforcement for the concrete structure walls. This study has calculated new reinforcement areas considering the above determined corrosion rate. Based on observed moisture collection, leakage and hence resulting potential future concrete rebar corrosion could occur in discrete localized. regions of the south wall. The sections where potential leakage is occurring were evaluated to determine the required area of steel to carry axial tension and flexure.

Comparing the required area of steel to the area of steel provided in the original design, enables the amount of acceptable reinforcing bar corrosion to be determined. Using a conservatively derived corrosion rate per year, the number of years of acceptable service for the pool from the onset of corrosion can be RffNo.487203ROO.ReV. 0" Page 20of88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit determined. This assessment identified a service life of at least twenty-six years (to reach code minimum reinforcement areas) and at least forty years based on calculated stress levels, if potential worst case corrosion effects were occurring. Potential exists the leakage could extend back to the 1990's timeframe, indicating the present operability acceptance of the structure with consideration of rebar degradation.

The approach utilized to derive service life, considers potential future degradation will occur at discrete regions of the wall. As the rebar corrodes, spalling of the concrete will occur due to the expansion of the rebar surface from corrosion products. Such potential spalling will occur at the areas where leakage is being observed. Adjacent regions of concrete reinforcement will remain protected from corrosion by the high pH passivating the rebar. To ensure the assessment performed was bounding, additional analytical cases were assessed.

These additional cases considered complete loss of both horizontal and vertical bars in a local region, along with consideration of complete loss of continuity along the observed indication at El. 64 ft.

Both bounding evaluations determined the wall capacity remained satisfactory to carry the applied loads.

Based on the above discussion, any potential degradation of the Indian Point Unit 2 Spent Fuel Pit Structure due to presently identified levels of pool water leakage will not adversely have an affect on its Class I safety function at the present time, or within the foreseeable future.

The present assessment of the SFP structure is considered a conservative assessment.

If corrosion were occurring as was considered in this evaluation, significant degradation would be expected to manifest itself by concrete cracks, spaHs, and rust bleeding.

Rebar degradation of the amount assumed in the study would likely yield local spalling of the pool walls. Evidence of such is not present on the excavated south wall, or along the identified wall crack or at the moist region of the wall at this time. Examination of the rebar from the core bores performed in the wall at the location of the observed moist region of the indication identified the rebar to be in excellent condition with no corrosion damage. Based on these observations it can be concluded the presently identified potential leak location(s) are not actively corroding the rebar and or such leakage is in the early stages of formation.

0 1, R e v. 0 Page 21 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit

6.0 REFERENCES

1.

Entergy Drawing No. 9321-F-1026, "General Concrete Notes"

2.

Entergy Drawing No. 9321-F-1196, "Fuel Storage Building Concrete Details -

Sheet 1".

3.

Entergy Drawing No. 9321-F-1202, "Fuel Storage Building Reinforcing Details -

Sheet 2".

4.

UE&C Calculation No. UEC-00035-00, "Fuel Storage Building", Vol. 12, Dated 09-30-66.

5.

Entergy Nuclear, "Updated Final Safety Analysis Report," Indian Point Unit 2

6.

Entergy Indian Point Unit 2 "Design Basis Document (DBD) for the Seismic Structures and Devices", Rev. 0.

7.

USNRC Information Notice 2004-05, "Spent Fuel. Pool Leakage to On-site Groundwater"

8.

Tremper B., "The Corrosion of Reinforced Steel in Cracked Concrete", Journal of the American Concrete Institute. Vol. 18, No. 10. June 1947.

9.

Entergy, Indian Point Unit 2 Technical Specifications

10.

Entergy, Record of Conversations. (Attachment C)

11.

American Concrete Institute (ACI)

A.

ACI-318-63, ACI-318-89, "Code Requirements for Concrete Structures" B.

ACI-222R-01,"Protection of metal in Concrete Against Corrosion" C.

ACI Materials Journal, Technical Paper, Title No. 85-M21,"Corrosion Rate Measurements of Reinforcing Steel in Concrete by Electrochemical Techniques".

12.

Florida Power and Light Company, Material Test Laboratory," Test Report Long Term Evaluation of Concrete Reinforcement Steel", Test Report P522-1471, General Engineering Dec. 27, 1988. (included as Attachment A)

13.

Kuenning, "Resistance of Portland Cement Mixture and ChemicalAttacks", 1966

14.

"Structural Engineers Handbook", Gaylord and Gaylord, McGraw Hill, Second Edition.

R.148..

PaR-g 1, 2 ov0 Page 22 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit

15.

Lucius Pitkin Inc, Report No. ME-3802 "Evaluation of Spent Fuel Pool Walls -

Indian Point 2 Nuclear Power Plant". March 26, 1993.

16.

Entergy Calculation No. CGX-00006-00, "Structural Evaluation of the Unit 2 Fuel Pool Wall Considering Deteriorated Condition of Concrete Due to Pool Leak".

March 11, 1993

17.

Computers and Structures, Inc., Berkeley, CA.

18.

ABS Consulting Nuclear Quality Assurance Manual (NQAM), Revision 7.

19.

ABS Consulting, "NQA Procedure for Software Verification and Control",

Procedure No. RCD-NQP-00-P03, Revision 1.

20.

ABS Consulting (EQE) Calc. 240063-C-009, "SAP2000 Version 7.4 Computer Program QA Verification", Rev. 0, Dec. 17, 2000.

21.

TID 7024, "Nuclear Reactors and Earthquakes", Lockheed Aircraft Corp. and Holmes & Navier, Inc. August 1963.

22.

ABS Consulting Report 1186959-R-007, Rev. 0 "Indian Point Unit 1 East Spent Fuel Pool and Rack Fitness for Service Inspection Report", Dec. 9, 2003.

23.

NUREG/CR-4652, (ORNL/TM-10059), "Concrete Component Aging and its Significance Relative to Life Extension of Nuclear Power Plants"'

24.

NUREG/CR-6679, "Assessment of Age -Related Degradation of Structures and Passive Components for U.S. Nuclear Power Plants".

25.

ACI 365.1R-00, "Service-Life Committee 365, January 2000.

Prediction -

State-of-the-Art Report". ACI

77

SU ng 6.-

4872037 RZOO1, R....0 Page 23 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit MOB N

Figure 1: Plan View Sketch of SFP & Adjacent Structures (NTS)

-n~F~

-.... No. 14872R3tR-No1, Rev. 0 Page 24 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit m *-

U. ~t -

Th ft Figure 2: FHB Looking North

$1 O~Fn~fflng

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Page 25 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit

ýWTITT TiT Observed crach ildication Figure 3: FHB Looking East f"

ffa Report No. 1487203-R-001, Rev. 0 Page 26 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit Figure 4: Crack Like Indication & Moist Region - Approx. El. 64 ft.

4"'A Idn Report No. 1487203-R-001, Rev. U Page 27 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit Approx. Thickness of South Wall4'- 0' Figure 5: Identified Indication in West Wall (Lkg. East from Pipe Pen)

Report No. 1487203-R-001 ReVT-O Page 28 of 88

Study of Potential Concrele Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit rj~eu Vertical Bar Exposed Figure 6: Photographs of Reinforcement in South Wall Exposed by Core Boring at Crack Like Indication - Upper Moist Region

ýkrAN$Conuftig Report No. 1487203-R-01*, Rbev.0O Page 29 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit Ingress of worosive. spevle's (into Vzous concrete.)

I~ IV.

Ccing and spalling of the concrots cboer Figure 7: Concrete Rebar Corrosion Mechanism (Results in Concrete Spalling)

%*it Report No. 1407203-R-00P

, Rev. 0 Page 30 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit oý Utw, Pdwbuiftn IwtEE_

To-*iiqn 10 paa w bTodimN.

dp 4

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M.4 Us Fig. 8-CarrosilOn rates of'reinforcing steel In Pon-crews w~ith differernt wic ratios, calculated by differehr feckniqruey (I inpy = 2,5.4 pmly)ý Figure 8: Rebar Corrosion Rate (Ref. 11.C) 7iidtn

-Rejporf _No. -1487203-R-OO1, -Rev. 0 Page 31 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit ChI~mw21 An21vIu~ nf ('nrp Rnr~ 5~amnIpq ~t ~rnitb W~dI Inulipqtinn Loc pH Co-60 Cs-Cs-137 Iron Boron uCi/gm 134uCi/gm uCi/gm ppM ppM Base 11.74 ND**

ND ND 96 159 Line 0-2" of 10.7 8.3 1E-05 2.65E-05 1.65E'03 628 72 crack 2-4" of 11.46 4.04E-05 I.39E-05 8.46E-04 640 56 crack 4-6" of 11.75 1.02E-05 ND 1.27E-04 3285

28 crack 1_1 6-8" of 11.79 ND ND 1.75E-05 60 226 crack I

drill nicked rebar

- ND - Not Discernable Table 1: Chemical Composition of Core Bores Taken at Identified Indication (Ref. 10)

~ABSQ~Isu~tng epoit& N14872O3CRýOo1, R' V.-O Page 32 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit Std o

otnil ocrt RifrcmntCrrso

,LoG of Cr1 1azs Loof Co Ctr Description Term Unit Ref Value NValue Value Value Steel bar Bar Desig T face D1 9321-1196 Ref2

8012 ", #801,2

11A9

9Q9

onfiguratl Bar Dia T face Dial in Ref. 14 1.000 1.000 1.410 1.128 on at Bar Area T face Abar-t in^2 Ref. 14 0.79 0.79 1.56 1

section Area adjustment 1 fool/spacing 1,00 1.00 1.33 1.33 Lnder Steel Area T face A's in^2 Area *Adjust 0.79 0.79 2.08 1.33 nvestigati Bar Deslg C face Dc 93211196 Ref. 2

8#12

8*12

9*9

119 on Bar Die C face Diac In Ref. 14 1.00 1.00 1.13 1.41 Bar Area C face Abar-c in^2 Ref. 14 0.79 0.79 1.00 1.56 Area adjustment 1 foot I spacing 1.00 1.00 1.33 1.33 Steel Area C face A"s in^2 Area

Adjust 0.79 0.79 1 33 2.07 Total Bar Area As In^2 A's+A"s 1.58 1.58 3.41 3.41 Code Min Reqd Area Amin Code in^2 0.0018 0 or 0.0025 0.86 0.86 1.44 1.44 Code Min Provided Amin Code/As OK OK OK OK Concrete Capacity based on as-designed section phi factor phI Sectl504 Ref. 11.A 0.851 0.85 0.85 0.85 Conc Strength L'c ksi 9321-1026 Ref. 1 1

3.00 3.00 3.00 3.00 Steel Yield fy ksl 9321-1026 Ref. 1 60.00 60.00 60.00 60.00 Axial Capacity Depth to cdr of ba Mom enl Capactl!

Applied Axial Loa Applied Moment Nu KIDs/ft Eon 4-1 40.291 40.291 67.83 105.81

!in 69321-1196 Ref. 2 44.50 44.50 43.44 43.44

- fK.ps-ft/ft Eqn 4-2 146.81 146.81 365.95 238.73 Kinsit.

lAttach..

17.301 17.301 33.00 33.00 I.

M klpS-Wt/t JAltacn t 22.001 110.001 88.00 131.00 Interaction Ratio JR1 Interaction Ratio IR2 IEq 4 -

M u

0.2g 0.

_Vei StiIj Vert Sit Horlz Stl Hartz StI LC1!LBase Loc of~n t

Require

ode Minimum Margin (1-1R) "100 57.061 25.071 51.35 45.13 Required Steel 5,reas Reouired C. face steel Areoa InA2 Eo-n 4-5 U.341 U.34 0.05 0.6b1 ADDIv Area Adiust 1 0r 9' 12" 0.341 0.34 0.49 0.491 Reouired T face steel A'reod in12 Eon 4-6 0.121 0.59 0.49 0.731 ApolV Area Adjust ANxlal SteellReqd Bar Die C Face Dia-c-r Check Wail Loss for A""reod tWt 9" / 12" Eqn 4-7a Eqn 4-8a Section 3.

Eqn 4-9a 0.121 0.59 0.36 0.79 0.34 F60OR 68 0,551 Required to Meet Code Minimum 0,43 0.43 0.56 0.88 0.43 0.43 0.42 0.60 7 043-0.43 0.88 0.56 0.43 -

0.43 0.66 o4 0.74 0.74 0.73 09 0.261 0.20 0.40 0.50 0.005 0.005 0.005.

0.005 52 26 99 79 CorSion rate C-Years of service YeS c-face Nyrs 69 69 1251 Moment Steel Check Read Bar Via T Face Dia-l-reqd in^2 Eon 4-7b 0.391 0.87 0.68 0.831 Wall Loss for A'reaod WL T face in Eon 4-8b 0.611 0.13 0.73 0.291 Corrosion ra Years-of ser I in/yr Section 3.2 0.00I 0.005 0.005 0.OC ace lyrs jEqn 4-9b 11221 271 146 Minimum service life Voft-rnin lvrs Ean 4-9c 27 68 sa9 82 Os 1.44 70!

Yo-in

-r Eqn. 4-9c 22 1!

2 Recheck Code minimum are O.ý;

3 1

O.9 U...

1.3J*

U 0.0.

U.86 1.44 1.44 Recheck Interaction I arli 77 sleel area s:

I

~

I 1

Corrodea t

ISea Eon 4-5 17.301 17.301

-i Note 1 Note 2 Note 3 Note 4 Table 2: Assessment of Wall Strength With Rebar Corrosion

~~sutAM-Report No. 1487203-R-001, Rev. 0 Page 33 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit Table 2 Notes:

I.

2.

3.

4.

5.

6.

Location of assessment at region of observed moisture - west edge of south wall.

Location of assessment at mid-point base of south wall - no corrosion is occurring at this region, YoS is not applicable.

Location of assessment at region of observed moisture - west edge of south wall.

Location of assessment is mid-point of wall, using (i.e. #9 bars carrying flexure), but using max. calculated moments from Cracked Case (Attachment B), thus this case is conservative since the moment in the middle of the wall is half the edge moment for a fixed end beam.

Moments and axial forces are derived in Attachment B based on the analysis performed.

Minimum service life, identified as Years of Service (YoS) calculated as 26 years (Vertical Steel), to meet Code minimum steel area. YoS calculated as 59 years (Horizontal Steel - see Note 4) based on steel required to carry loading. As such YoS exceeds the forty-year design life. Thus conservatively YoS is at least forty years.

~ABS ConsutUng Report No. 1487203-R-OO1, Rev. 0

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Report No. 1487203-R-001, Rev. 0 Page 34 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit ATTACHMENT A Boric Acid Corrosion Test Report (Ref. 12)

Re-pbrt NO. 1487203-R-OO61 Re§ý-'O-'

Page 35 of 88

I I

I, I

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I RESEARCH and EVALUATION LABORATORY Florida Power & Light Company LONG TERM CONCRETE REBAR TEST TEST REPORT P522-1471 Requested By:

G.

B. Coudriet, Power Plant Engineering Tested By:

H. L. Noto Reported By:

F.

prank I

I I

I Approved By:

4.e"(

Date: _/*Zo/J7 (44 P.R. Newnam (Supervisor)

Approved By-R2 N

,h Date:_4-1;-9a7 R. Shbarn P.E. (M4anager)

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I TABLE OF CONTENTS OBJECTIVE.......

REFERENCES.....

TEST SAMPLES....

EQUIPMENT MATERIALS.........................................

PROCEDURE RESULTS.........................

PHOTOS..

APPENDIX A (Request For Test).................

APPENDIX B (References).....................

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139-

I OBJECTIVE:

Evaluate the long term effect of borated water on reinforcing steel.

REFERENCES:

Bechtel Power Corporation Report on Florida Power and Light Company Turkey Point Units 3 and 4 Job Number 5177-54 "Effect of Water Leakage on Concrete and Rebar of the Spent Fuel Pool."

I TEST SAMPLES;

1)

Type "At- Sample 49

2)

Type "B" -

Sample G EQUIPMENT:

1)

Stainless steel tank and associated equipment, supplied by

.Turkey Point Plant.

2)

Mitutoyo Dial Calipers.

MATERIALS:

1)

Boric Acid Crystals: supplied by Turkey Point Plant.

2)

Demineralized water: approximately 40 gallons.

PROCEDURE:

Type '!A" specimen was placed on the upper tray (not submerged) in the4 stainless steel tank-The borated water solution dripped on the gapi of the specimen at the rate of 300 drops per minute for a period.!o0f 8 years.

Type "B" specimen was placed on the lower tray and submerged into the solution for the same time period as Type "A" specimen.

The two specimens were cut open and the surface condition of the rebars was examined.

The diameter of Type "B" rebar was measured prior to testing and after the test.

NOTE: During the last two years, immersion heater and pump motor failures occurred which caused the system to be down for some time until replacements could be located.

Once the equipment was repaired, the test was resumed.

(Mr.

J.

LeBleu was notified of Ithis condition) 1 i

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RESULTS:

A small quantity of Boron Concentrated Solution was taken from the tank to be analyzed at the Power Resources Laboratory.

The tank conditions were as following:

Specific Gravity................

1.006 Te p

r t

r

,e e..... e o o....,.

76OF Boron Concentration.............

2370 mg/l pH 7.40 NOTE: If necessary the tank conditions will be adjusted after the Research and Evaluation Laboratory relocates to Riviera Beach.

Type "A"

Sample #9 rebar was observed to have dark stains around the area where the boric acid solution dripped.

Some minor corrosion developed on the surface of the imbedded portion

-of the rebar and on the concrete.

Type "B"

Sample G rebar had moderate amounts of corrosion concentrated on the area which was directly in contact with the boric acid solution.

Dark spots were also observed on the concrete.

The diameter was measured to be 1.09 inches.

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RtS, coNSULT inG O*-SON www ab~sconsultincr corn

-I PHOTOS CONTINUED:.

PHO'TO Close-up of s sample G

showing dark spots on rebar.

Photo also shows corrosion concentrated in area exposed directly to the b o ric acid solution.

Some corrosion was also observed iil at the right end of the

~rebar.

I

-: ~

~

PHOTO 6:

Sample-G.

Photo shows some corrosion imbedded in the concrete.

Dark I

spots are also visible in -the concrete as well as the rebar.

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I PHOTOS CONTINL ED:

I I

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PHOTO

3:

Sample

9 was broken and examined after removing it from the Boric Acid Solution tank.

Dark stains were observed around area where the acid solution dripped.

PHOTO

4:

Sample

9.

Pýhoto shows only slight migration of, corrosion in the concrete.

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R(SK CONSULTING DIVISION WINI.

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I PHOTOS:

1.

PHOTO i:

Sample

9 was placed in the tank and the s

01 ut ion dripped on the gap of the specimen at the approximate rate of 300 drops per minute.

PHOTO 2:

Sample G

was submerged into the boric acid solution for 8 years.

RISK CONSULTING DIVISION

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I APPENDIX A (Request For Test)

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TAS, onuting RISK CONSUAXTING DIW$IONa www absconsuffina cor AIA IW2-x?2 -je-o,2J,, 90 4ký

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REQUEST FOR TEST SYSTEM TEST LABORATORY R F T o22L~

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.~-7 Piiorlty Test No.

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I Item to be tested Twenty concrete specimens as per attached sketch To evaluate the long-term effect of the leakage of borated water Purpose of tast on reinforcing steel Description of test _Ten specimens of each pri~m typ,."l IP pn*.-,=,

4-,

,r.,-a-y,a*_.-Z borated to the same concentrations as the PTP Spent Fuel Pits.

Type B prim will be submerged with a continuous flow of water.

Type A prisms will be above water level, but exposed to a trickling of water to simulate the leakage at PTP.

(Also see attached sheets)

Rb/er to Sizadzcrds-MATERIAL MANUFACTURFER CATALOG NO.

M NO.

G UAM.

To be furnished by Turkey. Point

[____I__

Test Requtst by G. B. Coudriet for Power Plant En-Dept.resultsneeded by At test intervals gineering Special Instructions Test specimens to be furnishid 'Gith stainless steel tank & equip-ment.

Water specifications to be furnished by PTP.

Caliper seasurements to be taken on.Type B prisms at each testing interval.

The surface condition of each specimen should be noted and documented by photographs at intervals specified.

C

,w *'Q,,the.

reinforcing steel Should bee:amned.,-rý cozos_*..,

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/44~923 - e-a

U.b REPORT OF EFFECT OF BORIC ACID LIQUID ON CQOCRETE AND REBAP

.APRIL 8, 1976 The effects of boric acid liquid on concrete and rebar has been reviewed and reported results in published sources were included in the study.

A limited list of references is given in Attachment S-2o.

These references are available and some of the items are attached as. excerpts or full text for ccnvenient use in conjunction with these co"u ents.

1.

A question has been raised on the long-ter; effect of the leakage water in the corroding of the rebar where exposed to trickling fluid at leaking construction joints.

We are -on record as giving assurance that the short-term effect over a period of 6 months to 1 year on the. rebar would be negligible.

We are expected to I

give some further long-term assurance or recommend some type of

-effective repair that would minimize or eliminate the possibility I

of rebar corrosion.

2.

We reached the conclusion that the effect of boric acid solution on the concrete from this exposure would be non-detrimental.

This was stated :in the January 1975 report.

a.

Boric acid concentration of 2,000 ppm at 120°F vill not I

be detrimental.

The.evidence available is given in published data from PCA exposures of small mortar speci-mens at ordinary room temperature.

b While it would be reasonable to project (or extrapolate) such data as applicable at elevated te.peratures, there are no data in support of such projections.

It appears that boric acid would be non-corrosive and non-deleterious at 1200-F but some actual exposure of concrete or mortar specimens should be conducted to validate this opinion.

I

3.

The effect of the leakage water on the concrete is probably dependent primarily on the pR.of the leakage water because our earlier information had indicated that substances other than boric acid or borates were present in very low concentrations.

In water test data reviewed November I.S74, the amounts of chloride, fluoride, and silica determined in the water were found to be negligible; thus neutral or alkaline solutions of borates should not have an

.erosive or corrosive effect on the concrete surfaces.

Also, if the concrete surfaces were so affected, it should be evident by this time.

VABS Consulting RtSK CONSWIfNG DIVLSION www~atmconsctdfnaxcor II II n

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4.

It is still believed that exposure of molded concrete prisms to actual or simulated trickling action of the spent fuel pool water should be undertaken at this time so that experir-'ntal observa-tions can be made a year hence for projectioxr of long-term effects.

To consider the possible effects on rebar from this leakage we examined a recent paper authored by corrosion specialists of the Florida Department of Transportation.

This paper on "The Fundamentals of Corrosion' by R. P. Brown and R. J. Kessler was presented at.-he TRB Corrosion Session by R. Scratful, Chairman of Corrosion Committee.

Derived from review of this text, as the primary benefit from their presentation, is a listing of forms of corrosion as Attachment S-3.

5.

From the items on S-3 it appears that pitti-ng corrosion and erosion of rebar metal are the forms of greatest concern which could result from the present conditions at Turkey Point. I(If corrosion

'/

is active, chemical tests should be able to detect pickup of iron

~

in the leakage Tater caused by dissolution; this factor would be I

confirmed if staining of concrete were noticeable.

6.

LOwptE on the acid side (less than pWT) and dissolved oxygen are critical factors conducive to corrosion of rebar.

There is no evidence that we have received any spe~ific data on the amount of dissolved oxygen in the leakage water.

There is no condition suggesting alarm but we need to have some information on this and other constituents dissolved in the water besides borates, or some evidence that other substances are not present.

7.

Sealing off the leakage by grouting or sealant application would minimize corrosive influences and these possibilities will be consid ered.

8.

We need additional current test data which defines the composition of any impurities present in the leakage water.

If the pR of the

' water has been measured periodically during the past year this information would be very useful.

The surface condition of concrete in structure exposed to the leakage should be determined and reported.

We should receive a report of an appraisal og the present condition at these locations.

9.

Recommendation of Test Exposures -

The sketches of Sheet No. S-I attached shows two possible types of concrete prism/specimens that could be exposed over long periods Of time under actual or simulated job conditions.

Type A specimens could be made for observations at six months, one year, two.years, and later; Type B specimens in duplicate could be monitored at intervals such as one mouth, three months, six months, one year,

etc,

.Tie liquid shiaun3.dflow-arra=incd-hest..el by trickl*niý_troj~ugLh_.

-crevice gap formed in TypeA specimen.

If not fUTwgion Type B specimei", *thd-l(-jid should be changed at least weekly.

Preferably the experiment should be set up to run by itself with little attention required until time to take thb"reading".

ABS Consulting RISK CONSUkTING DiVSI0N www, abconsu/tin, corn

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I References Related to Corrosive Effects on Concrete and Steel Reinforcing Bars.

1.

"The Effect of Acid Waters on Concrete", B. Trempez ACX Title No.

28-I Sept. 1931 ACI Journal.

2.

"The Corrosion of Reinforcing Steel in Cracked Concrete", B. Tre per ACt Title No. 43-40 June 1947-ACI Journal.

2.a. Discussion of ACT TLtle No. 43-40, A. Weiner p. 1144-I, Part 2 Dec. 1947 ACI Journal.

3.

"Corrosion of Reinforcing Steel",

B. Tremper, in ASTM STP 169-A on Significance of Tests and Properties of Concrete and Concrete

aking, Materials, p. 220-229 (lists 35 references) 1966.

4.

"Durability of Concrete in Service" ACI Coumittee 201 Report, Chapter 5, "Corrosion of Reinforcement in Concrete", Hubert Woods, Chairmau ACX Title 1*o.

59-57 Dec, 1962 Journal and Manual of Concrete Practice Part 1.

5.

Abstract of "Durability of Concrete Construction", Hubert Woods ACI Monograph I~o. 4 (1968) p. 670-672, Aug. 1968 ACE Journal.

6.

I "Resistance of Portland Cement Mortar to Chemical Attack - A 'Progress Report", W. 1. Kueuning, REghýay Research Record Number 113 UR Pub-licatioa 1335 (1956),

Reprinted as PCA Research Dept. Bulletin 204.

Participants:

John Skonieczny (Entergy)

Paul Bruck (ABS Consulting)

Subject:

Unit 2 Spent Fuel Pit - Fuel Pool Water Make-up Discussion:

We discussed the limits of the Unit 2 spent fuel pool water, based on limits listed in Tech Specs, namely:

Chlorides

</= 1.5 ppm pH 4.0 - 8.0 Conductivity </= 20 pis/cm Boric Acid

> 2000 ppm I had requested typical values of pH and an upper limit on boron in the pool. John reported these values are pH typically 4.8, Boron less than 2,400 ppm.

R. 2, Paul M. Bruck, September 12, 2005

~'*APSCm~sitInU

.R6e-po6t&

1487203-R-OOI.reV. 0 Page 86 of 88

Study of Potential Concrete Reinforcement Corrosion on the Structural Integrity of the Spent Fuel Pit RECORD OF COVERSATION

Participants:

John Skonieczny (Entergy)

Paul Bruck (ABS Consulting)

Subject:

Unit 2 Spent Fuel Pit - Chemical Analysis of Fines From 6" Depth Drill into South Wall at Crack Location Discussion:

Based on discussions on Friday September 9th, 2005, ABS Consulting had requested Entergy drill a pilot hole into the south wall of the SFP in the region of the crack to enable pH readings to be taken from concrete fines extracted from the drill bit. The results of the chemical analysis of the fines from the drilling are listed below.

Chemical Analysis of Core Bore Samples at South Wall Indication Loc pH Co-60 Cs-Cs-137 Iron Boron uCi/gm 134uCi/gm uCi/gm PPM ppM Base 11.74 ND**

ND' ND 96 159 Line 0-2" of 10.7 8.3 1E-05 2.65E-05 1.65E-03 628 72 crack 2-4" of 11.46 4.04E-05 1.39E-05 8.46E-04 640 56 crack 4-6" of 11.75 1.02E-05 ND 1.27E-04 3285

28 crack 6-8" Of 11.79 ND ND 1.75E-05 60 226 crack

drill nicked rebar ** ND - Not Discernable 2,

Paul M. Bruck, September 12, 2005

_9 ions.

Re6port No. 1487203-R-0-01 Rev. 0 Page 87 of 88

Study of Potential Concrete Reinforcement Corrosion on Structural Integrity of the Spent Fuel Pit ATTACHMENT D NQP-02 Exhibit 1 Review Guidelines Status Criterion Design Attributes (S, U, N/A)

1.

Were the inputs correctly selected and incorporated into design?

2.

Are assumptions necessary to perform the design activity adequately described and reasonable? Where necessary, are the assumptions identified for subsequent re-verifications when the detailed design activities are completed?

3.

Are the appropriate quality and quality assurance requirements specified?

4.

Are the applicable codes, standards and regulatory requirements including issue and addenda properly identified and are their requirements for design met?

5.

Have applicable construction and operating experience been considered?

II 01IY

6.

Have the design interface requirements been satisfied?.

7.

Was an appropriate design method used?

8.

Is the output reasonable compared to inputs?

9.

Are the specified parts, equipment, and processes suitable for the required application?

____//__*

10.

Are the specified materials compatible with each other and the design environmental conditions to which the material will be exposed?

11.

Have adequate maintenance features and requirements been specified?. ?

12.

Are accessibility and other design provisions adequate for performance of needed maintenance and repair?

13.

Has adequate accessibility been provided to perform the in-service inspection expected to be required during the plant life?

14.

Has the design properly considered radiation exposure to the public and plant personnel?

15.

Are the acceptance criteria incorporated in the design documents sufficient to allow verification that design requirements have been satisfactorily S

accomplished?

16.

Have adequate pre-operational and subsequent periodic test requirements been appropriately specified?

17.

Are adequate handling, storage, cleaning and shipping requirements specified?

18.

Are adequate identification requirements specified?

19.

Are requirements for record preparation review, approval, retention, etc.,

adequately specified?

Design Reviewer:

Date: ~

5~

SABS Consulting Film CmaSUaG DwI sOt.

Repol.nNo. 14812U3-H-QU1,

-ev. u Page E 9f

ML103481101

Contents

Text

1.0 INTRODUCTION

5.0 CONCLUSION

6.0 REFERENCES

1.0 INTRODUCTION

5.0 CONCLUSION

6.0 REFERENCES

77

REFERENCES:

Participants:

Subject:

Participants:

Subject:

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ML103481101

Text

1.0 INTRODUCTION

5.0 CONCLUSION

6.0 REFERENCES

1.0 INTRODUCTION

5.0 CONCLUSION

6.0 REFERENCES

77

REFERENCES:

Participants:

Subject:

Participants:

Subject:

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