ML20115E030

Proposed TS Table 3.6.B.2-1,raising Reactor Water Conductivity Limit to Support Implementation of Noble Metal Chemical Addition at Plant as Method to Enhance Effectiveness of HWC in Mitigating IGSCC

ML20115E030
Person / Time
Site:	Duane Arnold
Issue date:	07/05/1996
From:	IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT
To:
Shared Package
ML20115E028	List: ML20115E030 NG-96-1297, Application for Amend to License DPR-49,consisting of TS Change Request RTS-290,revising TS Table 3.6.B.2-1 to Raise Reactor Water Conductivity Limit to Support Implementation of Noble Metal Chemical Addition
References
NUDOCS 9607160068
Download: ML20115E030 (6)

Text

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RTS-290 Attachment 2 to

,. .. NG-96-1297 Page1of1 ERO. POSED CHANGE (RTS-290)TO THE DUANE ARNOLD ENERGY CENTER l TECHNICAL SPECIFICATIONS l

The holders oflicense DPR-49 for the Duane Arnold Energy Center propose to amend Appendix A (Technical Specifications) to said license by deleting certain current pages and replacing them with the attached, new pages. The List of Affected Pages is given below.

1 LIST OF AFFECTED PAGES l 3.6-4 3.6-6 3.6-21 l

SUMMARY

OF CHANGES:

The following list of proposed changes is in the order that the changes appear in the Technical Specifications (TS).

1 Eage Descrintion of Changes 3.6-4 Add monitoring frequency to Sections 4.6.B.2.c and 4.6.B.2.d for chloride and acidity (pH) during Noble Metal Chemical Addition (NMCA).

3.6-6 Add two asterisks to the conductivity limit for the STARTUP/ HOT I

SHUTDOWN Modes in Table 3.6.B.2-1.

3.6-6 Add the higher limit (10.0 pmhos/cm) and explanation for the NMCA process below the Table.

l 3.6-21 Add the bases for the NMCA process.

l l

9607160068 960705 l PDR ADOCK 05000331 1 P PDR

DAEC-1 L'NITING I CONDITIONS FOR OPERATION SURVEILLANCE REOUIREMENTS

2) With the conductivity c. Obtain and analyze a sample exceeding 10.0 ymho/cm at of the reactor coolant for 25'c or chloride chlorides at least once concentration exceeding ev W 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> whenever44.h ;

500 ppb, be in at least HOT 44 condactivity is greater than SHUTDOWN within the next the limit specified in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD Table 3. 6. B. 2-1, dt MS M 44 SHUTDOWN within the M4hi. C44c4 AdA"*. )

following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. d. Obtain and analyze a sample--

of the reactor coolant for pH at_least_once every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> whenever .sd h ,

t44, conductivity is greater than the limit specified in i Table 3.6. B.2-1, OA, M

3) Continuously record the 4.144. Mitdt cheni. A  %. I

conductivity of the reactor a coolant. With no e. With no continuous recording continuous recording conductivity monitor conductivity monitor OPERABLE, obtain an in-line OPERABLE, install a conductivity measurement at temporary in-line least once per 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> when conductivity monitor within in RUN, STARTUP, or HOT 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> or be in at least SHUTDOWN MODES and 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> HOT SHUTDOWN within the at all other times.

next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. f. Perform a CHANNEL CHECK of the continuous conductivity monitor at least once per 7

b. In STARTUP and HOT SHUTDOWN: days.

4

1) With the conductivity, i chloride concentration or pH exceeding the limit specified in Table 3.6.B.2-1 for more than 48 continuous hours, be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

c. In COLD SHUTDOWN and REFUEL:

1) With the conductivity or pH exceeding the limit specified in Table 3.6.B.2-1, restore the conductivity and pH to within the limit within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

l 2) With chloride concentration exceeding the limit

specified in Table 3.6.B.2-1, restore

., the chloride concentration to within the limit within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

RTS 290 AMENDMENT NO. 203 3.6-4 7ah5,l9%

Correction letter, dated 8/4/93

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DAEC-1 dependent corrosion rates and provide time for the RWCU System to.re-establish *l the purity of the reactor ecolant. During some periods of operation, conductivity or chloride cencontration may exceed 5.0 pmo/cm or 200 ppb j respectively because of the initial evolution of gases, the initial addition I of dissolved metals, or the breaking out of chlorides entrapped in the system.

The total time during which the conductivity or chloride concentration may exceed the specified limit must be limited to 2 weeks / year or less to prevent stress corrosion cracking.

At DAEC, conductivity is continuously monitored at the Reactor Water Cleanup System, between the hot well and the domineralizer beds, and at the outlet of the domineralizar beds. Any of these monitors are considered to fulfill the requirement of continuously monitoring the Reactor Coolant System. In the event that the conductivity cannot be continuously monitored, a temporary in-line monitor iu to be installed.

The iodine radioactivity will be monitored by reactor water sample analysis.

The total iodine activity would not be expected to change over a period of 1 week In addition, the trend of the offgas stack release rate, which is l continuously monitored, is an indication of the trend of the iodine activity in the reactor coolant. Since the concentration of radioactivity in the reactor coolant is not continuously measured, coolant sampling would be ineffective as a means to rapidly detect gross fuel element failures.

However, the capability to detect gross fuel element failures is inherent'in the radiation monitors in the offgas system and on the main steam lines.

The conductivity of the reactor coolant is continuously monitored.

Conductivity instrumentation will be checked every 3 days by instream l measurements with an independent conductivity monitor to assure accurate readings. If corsductivity is within its normal range, chlorides and other impurities will also be within their normal ranges. The reactor coolant samples will also be used to determine the chlorides. Therefore, the sampling frequency is considered adequate to detect long-term changes in the chlor.ide ion content. Isotopic analyses to determine major contributors to activity can be performed by a gamma scan, f Noh M CA'"4 AddOb ( d " CA) b A 'A'442*P6L % #

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h to 48a T f a c 4g4 - RT5 J80 AMENDMENT NO. 7J,203 3.6-21 -gg 5, M

l RTS-290 Attachment 3 to i

NG-96-1297 Page1of1 ENVIRONMENTAL CONSIDERATION i i

i 10 CFR Section 51.22(c)(9) identifies certain licensing and regulatory actions which are eligible {

for categorical exclusion from the requirement to perform an environmental assessment. A l proposed amendment to an operating license for a facility requires no environmental assessment if operation of the facility in accordance with the proposed amendment would not: (1) involve a '

significant hazards consideration; (2) result in a significant change in the types or significant increase in th. amounts of any effluents that may be released offsite; and (3) result in a i significant increase in individual or cumulative occupational radiation exposure. IES Utilities l Inc. has reviewed this request and determined that the proposed amendment meets the eligibility I criteria for categorical exclusion set forth in 10 CFR Section 51.22(c)(9). Pursuant to 10 CFR Section 51.22(b), no environmental impact statement or environmental assessment needs to be prepared in connection with the issuance of the amendment. The basis for this determination l

follows:

lhuiis The change meets the eligibility criteria for categorical exclusion set forth in 10 CFR Section 51.22(c)(9) for the following reasons:

1. As demonstrated in Attachment I to this letter, the proposed TS amendment does not )

involve a significant hazards consideration.

2. The proposed TS amendment will only permit a higher value of the reactor water conductivity limit during the application period of Noble Metal Chemical Addition (NMCA). During and after the application, excess ions will be removed from the reactor water by the Reactor Water Cleanup (RWCU) system and the conductivity will be l restored to the limit specified in Section 3.6.B. The deposited layer of noble metals is beneficial for mitigating Intergranular Stress Corrosion Cracking (IGSCC) in reactor l vessel internal components. Therefbre, the proposed TS amendment will not result in a significant change in the types or a significant increase in the amounts of any effluents that may be released ofTsite.

3. As is discussed above, NMCA process is developed as a method to mitigate IGSCC in reactor vessel intemal components in conjunction with the liydrogen Water Chemistry (IIWC). Use of NMCA allows lower injection rates of HWC which in turn reduces plant radiation exposure over the life of the plant. Therefore, the proposed TS amendment will not result in an increase in either individual or cumulative occupational radiation exposure.

(

l RTS-290 Attachment 4 to

,. NG-96-1297 Page1of1 SAFETY ASSESSMENT

1. Introduction By letter dated July 5,1996, IES Utilities Inc. requested changes to the Duane Arnold Energy Center (DAEC) Technical Specifications (TS). The proposed TS amendment will permit a higher value of the reactor water conductivity limit during the application period of Noble Metal ,

Chemical Addition (NMCA). l The NMCA project at the DAEC is part of ongoing efforts to maintain the integrity of reactor vessel internal components and to limit increases in plant radiation exposure over the life of the plant. NMCA has been developed by General Electric Nuclear Energy (GENE) and an overview of NMCA has been discussed between the NRC and IES Utilities Inc. and GENE during a public meeting held on May 6,1996.

2. Assessment NMCA process will deposit a very thin, discontinuous layer of the noble metals on all wetted surfaces during the application period. The treated surfaces will behave catalytically and promote oxidant-hydrogen recombination to reduce corrosion potentials. Hence, a treated surface combined with a low Hydrogen Water Chemistry (HWC) injection rate will reduce the propensity for Intergranular Stress Corrosion Cracking (IGSCC). Lower injection rate of HWC reduces plant radiation exposure over the life of the plant.

During the application period of NMCA, it is expected that the reactor water conductivity will increase and exceed the conductivity limit of 2.0 micromhos per centimeter ( mhos/cm) I specified in the DAEC TS. The expected increase in conductivity is due to the effect of noble metals on conductivity and is appropriate during the application. The deposited layer of noble metals is beneficial for mitigating IGSCC in reactor vessel internal components.

During and after the application, the Reactor Water Cleanup (RWCU) system will continue to operate to remove excess ions and restore the reactor water conductivity to the limit specified in J Section 3.6.B.  !

I Based upon the above assessment, we conclude that this proposed TS change is acceptable. l l

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