ML20134K550

Application for Amends to Licenses NPF-2 & NPF-8,requesting Deletion of TS 3.6.2.2 Re Containment Spray Additive Sys

ML20134K550
Person / Time
Site:	Farley
Issue date:	11/15/1996
From:	Dennis Morey SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20134K554	List: ML20134K550 ML20134K555
References
NUDOCS 9611190190
Download: ML20134K550 (11)

Text

, Southern Nuclxr Operiting Company i' " Post Offics Box 1295 Birmingham, Alibima 35201 T;l?phona (205) 868-5131 L

o. . uorey Southem Nudear Operating Company Vice President Farley Project the southem electnc system November 15, 1996 l

i 10 CFR 50.90 Docket Numbers: 50-348 50-364 i U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Joseph M. Farley Nuclear Plant Request For Technical Specification Changes Elimination of Containment Spray Additive System Ladies and Gentlemen:

In accordance with the provisions of 10 CFR 50.90, Southern Nuclear Operating Company (SNC) proposes to amend the Farley Nuclear Plant (FNP) Unit I and Unit 2 Technical Specifications, Appendix A to Operating Licenses NPF-2 and NPF-8. This amendment will result in the deletion of containment systems specification 3.6.2.2, " Spray Additive System." his specification will be replaced with a new emergency core cooling system specification 3.5.6, "ECCS Recirculation Fluid pH Control System." The spray additive system will be spared in place or removed. The spray additive system will be replaced with an alternate means of pH control of the ECCS recirculation fluid. For Unit 2 Technical Specifications, the spray additive tank discharge valves will be deleted from specification table 3.8-2 for thermal overload bypass devices of safety-related motor-operated valves.

The conta' rent spray system (CSS) is an engineered safety features system that functions to reduce reactor containment building pressure and temperature and the quantity of airbome fission products in the containment atmospere subsequent to a loss of coolant accident (LOCA). Pressure and temperature reduction is accomplished by spraying water into the containment atmosphere. Sodium hydroxide is currently added to the containment spray water to increase the pH which enhances absorption of the airborne fission product iodine, retains the iodine in the containment sump solution, J l

minimizes hydrogen production, and inhibits chloride induced stress corrosion cracking. The CSS currently uses the spray additive tank (SA'l) to provide the caustic containment spray. Technical Specifications require SAT related tests and maintenance to be performed. This testing and i maintenance is resource intensive, and the handling of concentrated sodium hydroxide solution requires I special precautions due to its hazardous nature. l I

Draft revision 2 to the Standard I.cview Plan (SRP) section 6.5.2, " Containment Spray as a Fission Product Cleanup System," and industry precedence have made it possible to eliminate the spray additive portion of the CSS. The methodolegy of SRP 6.5.2 states that post-accident injection phase removal of i elemental iodine (the predominant form) from the LOCA containment atmosphere is essentially  !

independent of spray pH. This provides the basis for the climination of the spray additive portion of the CSS, including the SAT, as well as the basis for the attendant Technical Specifications changes.

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9611190190 961115 PDR ADOCK 05000348 p PDR

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U. S. Nuclear Regulatory Commission Page 2 The removal of the spray additive does not eliminate the need for adjusting the pH of the ECCS recirculation solution. To assure that the iodine removed by the sprays is retained in solution, to minimize i

chloride induced stress corrosion cracking on mechanical systems and components, and to minimize the  ;

hydrogen produced by the corrosion ofgalvanized surfaces and zinc-based paints, the long-term pH of the ECCS solution should be no less than 7.5. Since the initial pH of the boric acid ECCS solution, without -

spray additive, will be approximately 4.5, a chemical additive must be utilized to raise the pH of the  ;

solution in the containment building sump. l l The proposed replacement for the liquid sodium hydroxide (NaOH) spray additive system consists of i I

trisodium phosphate (TSP) stored in baskets located in the post-LOCA flooded region of the contamment l

building. The initial containment' spray (injection phase) will be a boric acid (2,300 to 2,500 ppm range) i solution from the refueling water storage tank (RWST), which has a pH of approximately 4.5. As the l initial spray solution, and subsequently, the recirculation solution comes in contact with the TSP, the TSP  !

l dissolves, raising the pH of the sump solution to an equilibrium value of 7.5 or greater.

The proposed recirculation fluid pH control system will have the same function as the present spray additive system; that is, to mitigate the effects of a LOCA. The change to a passive pH control system will ,

eliminate the possibility of an active spray additive component failure.

SNC plans to replace the spray additive system during the next Unit I refueling outage in the Spring of l 1997. The same change will be implemented during the Unit 2 refueling outage in the Spring of 1998. The ,

Technical Specification changes are requested to be approved by March 8,1997, in order to facilitate the replacement of the spray additive system during the next Unit I refueling outage. SNC requests implementation of the FNP Unit 1 Technical Specification changes prior to Mode 4 following the Spring of  ;

i 1997 refueling outage. SNC requests implementation of the FNP Unit 2 Technical Specification changes l l prior to Mode 4 following the Spring of 1998 refueling outage.  !

This requested change is a Cost Beneficial' Licensing Action (CBLA). The estimated savings over the life j of both units is approximately $500,000. .j 1

Enclosure 1 provides a safety assessment for the proposed changes. Enclosure 2 provides the basis for a I determination that the proposed changes do net involve significant hazards considerations pursuant to 10  ;

CFR 50.92. Enclosure 3 provides the proposed changes to the Unit 1 Technical Specifications. Enclosure 4 provides the proposed changes to the Unit 2 Technical Specifications. Enclosure 5 provides the Units I and 2 marked-up Technical Specification pages.

As denoted in 10 CFR 50.92(c), SNC has determined the proposed changes to the FNP Tecimical Specifications do not involve a significant hazards consideration. The basis for this evaluation is provided in Enclosure 2. SNC has also determined that the proposed changes will not significantly affected the quality of the human environment. A copy of the proposed changes has been sent to Dr. D. E. Williams, the Alabama State Designee, in accordance with 10 CFR 50.91(b)(i).

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Mr. D. N. Morcy states that he is a vice president of Southern Nuclear Operating Company, and is authorized to execute this oath on behalf of Southern Nuclear Operating Company and that, to the best of i his knowledge and belief, the facts set forth in this letter and enclosures are true.

Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY (5h bZM4 i Dave Morey

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i DRC:mafELIMCTM4. Doc SWORN TO AND SUBSCRIBED BEFORE ME

Enclosures:

THIS DAY OF der ,1996 ,

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0 R 0 92 Fv luation Unit 1 Technical Specification Pages

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' Notary Plf61ic db

4. Unit 2 Technical Specification Pages

5. Units 1 & 2 Marked-Up Technical Specification Pages MY COMMISSION EXPIRES: 2IE4/N7 j

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cc: U. S. Nuclear Regulatory Commission Mr. S. D. Ebneter, Regional Administrator Mr. J. I. Zimmerman, Licensing Project Manager, NRR Mr. T. M. Ross, Senior Resident Inspector, Farley  ;

State of Alabama Dr. D. E. Williams

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Enclosure 1  ;

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j Joseph M. Farley Nuclear Plant

! Elimination of Containment Spray Additive System

Technical Specification Changes l

Safety Assessment i

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Enclosure 1

I Joseph M. Farley Nuclear Plant l

! Elimination of Containment Spray Additive System i Technical Specification Changes Safety Assessment l 4

i j introduction The Farley Nuclear Plant NPF-2 and NPF-8 Technical Specifications for the

! emergency core cooling systems (Technical Specification 3/4.5) and the containment spray additive system (Technical Specification 3/4.6.2.2) are proposed 1

to be revised. The Farley Nuclear Plant NPF-8 Technical Specifications for the

! electrical protection devices (Technical Specification 3/4.8.3) are also proposed to be revised. The following is a summary of these proposed changes:

1. Add a new specification 3/4.5.6 for recirculating solution pH control to provide a l means for raising the pH of the recirculated sump solution into the range of 7.5 to 10.5.

2. Delete the current specification 3/4.6.2.2 for limiting conditions for operations and surveillance requirements in its entirety.

3. For NPF-8 license, delete the spray additive tank discharge valves 2HV-8836A, B from the current specification table 3.8-2 for thermal overload bypass devices of safety-related motor-operated valves.

4. Revise specification bases 3/4.1.2 and 3/4.5.5 to indicate the range in pH for the ECCS recirculatica fluid to be from 7.5 to 10.5 to minimize the potential for chloride and caustic induced stress corrosion cracking on mechanical systems and components, and ensure retention of iodine in the sump solution.

5. Add the bases for new specification 3/4.5.6 describing the requirement to raise the pH of the recirculated sump solution into the range of 7.5 to 10.5 to minimize the potential for chloride and caustic induced stress corrosion cracking on mechanical systems and components, and ensure retention of iodine in the sump solution.

6. Delete the bases for 3/4.6.2.2.

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.- Enclosure 1 I

Safety Assessment 1

l Safety Analysis Discussion and Evaluation Draft Revision 2 to the Standard Review Plan (SRP) Section 6.5.2, " Containment Spray as a Fission Product Cleanup System," and industry precedence have made it possible to eliminate the spray additive portion of the containment spray system.

The methodology of SRP 6.5.2 identifies that post-accident injection phase removal of elemental iodine (the predominant form) from the LOCA containment atmosphere is essentially independent of spray pH. Thus, this change eliminates the spray additive portion of the containment spray system, including the spray additive tank (SAT).

The removal of the spray additive does not eliminate the need for adjusting the pH of the emergency core cooling system (ECCS) recirculation solution. To assure that the iodine removed by the sprays is retained in solution, to minimize chloride induced stress corrosion cracking on mechanical systems and components, and to minimize the hydrogen produced by the corrosion of galvanized surfaces and zinc-based paints, the long-term pH of the ECCS solution should be no less than 7.5.

Since the initial pH of the boric acid ECCS solution, without spray additive, will be approximately 4.5, a chemical additive must be utilized to raise the pH of the solution in the containment building sump.

The replacement for the liquid sodium hydroxide (NaOH) spray additive system consists of trisodium phosphate (TSP) stored in baskets located in the post-LOCA flooded region of the containment building.

The initial containment spray (injection phase) will be a boric acid (2,300 to 2,500 ppm range) solution from the refueling water storage tank (RWST), which has a pH of approximately 4.5. As the initial spray solution and subsequently the l recirculation solution comes in contact with the TSP, the TSP dissolves, raising the pH of the sump solution to an equilibrium value of 7.5 or greater.

The proposed recirculation fluid pH control system will have the same function as the present spray additive system; that is, to mitigate the effects of a LOCA. The change to a passive pH control system will eliminate the possibility of an active spray additive component failure. Eliminating spray additive will also minimize the exposure of plant personnel to the caustic NaOH and reduce plant testing and maintenance resources currently required for the system.

The components associated with the spray additive system are being either spared in place or removed. The blind flanges installed in the eductor lines will meet ASME Section lli Class 3 requirements. The containment spray piping will continue to meet the plant seismic and ASME Section lli Class 3 requirements.

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' Safety Assessment l

l Level indicators and flow indicators and the hand switches will be removed from the l Main Control Board (MCB) and replaced with cover plates. These changes do not result in any significant mass variation when compared to the overall MCB mass.

l The MCB's response to seismic input will be unaffected by this change and can still j be considered seismically qualified.

Three (3) TSP storage baskets will be located in the recirculation sump area with a total minimum capacity of approximately 10,000 pounds (185 cubic feet) of TSP

compound as Na3PO4 12H 2O %NaOH (or appropriate weights / volumes for i equivalent compounds). An equivalent amount of trisodium phosphate compound l'

with a different chemical formula may be used. When equivalent compounds are used, the allowable weights / volumes may be different; however, the equivalent .

amount of trisodium phosphate compound must raise the pH of the recirculating i solution into the range of 7.5 to 10.5. The baskets are designed to Seismic l l Category 1 standards and will be bolted (anchored) to the filler slab at elevation ,

105'-6". The seismic accelerations for the base slab were used in the seismic l design of the baskets. The natural frequencies of each basket were used in  !

j determining the seismic loads for each basket.

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l The metal mass for the three TSP baskets and supports adds a heat sink to the '

I containment, and the deletion of the SAT water inventory removes a heat sink. The

! Impact of the additional metal heat sink on the peak clad temperature (PCT) has

! been reviewed and determined to be acceptably small, less than +1 F, so that the  !

i requirements of 10 CFR 50.46 continue to be met.

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! The high energy pipe break analysis described in FSAR Section 3.6 was reviewed I for jet impingement on the TSP baskets. The results indicated that there is one

case where a pipe break jet may impinge on one of the TSP baskets. A 1/4" plate i was added to the two sides potentially impacted. This will not reduce the dissolution rate of the TSP as no credit is taken for dissolution of TSP from the l basket sides. The basket loads were then evaluated and determined to be j acceptable.

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j. The flooded post-LOCA recirculation sump level will not be significantly changed

(i.e., <1/2") due to the addition of the TSP and the TSP baskets and deletion of the l SAT water volume, and thus does not warrant revision as the equipment located

] above the sump flood level would remain above the flooded post-accident ,

! environment. Further, the deletion of the unborated water volume in the SAT will i result in a small, but insignificant, increase in the boron concentration of the i recirculation fluid.

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. Enclosure 1 ]

Safety Assessment i

[ Analyses were conducted to ensure that effects such as vortexing, reduction of net j positive suction head (NPSH), and screen blockage will not result in degraded i

residual heat removal (RHR) or containment spray pump / system performance.

l Containment sump hydraulic model studies were previously performed to determine if the intake velocities at the sump intakes were large enough to create pump l

l suction vortex problems. The results o' these studies indicated that there were no 4

problems when the grating cage and tis i-rack screen were installed over the j sumps. The proposed change will not have an adverse impact on the function of

' the grating cage or the trash-rack screen to minimize pump suction vortex problems.

Therefore, there is no adverse effect on the previous sump hydraulic model studied.

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!- The pH of the sump solution will be adjusted to at least 7.5 to counteract the buildup i of chloride concentrations to critical levels. Equipment in containment will be exposed to a low pH solution (approximately 4.5) for a short period of time during

the spray injection phase. During this time, the TSP will begin to dissolve and the

! pH of the ECCS sump solution will be raised into the range of 7.5 to 10.5. The i surfaces sprayed during the injection phase will eventually be re-sprayed during the recirculation phase with a high pH solution. Materials qualified for long term exposure to a high pH solution will not be adversely affect by short term exposure to a low pH solution.

4 Aluminum and zinc corrosion are sources of possible hydrogen generation affected l

by this change. The proposed change will affect the pH by introducing an initial pH j of 4.5 (borated water spray) followed by a pH range of 7.5 to 10.5 using TSP. This

is effectively a lower pH than the current range of 8.5 to 11.0, using sodium j hydroxide. The corrosion of aluminum decreases with decreasing pH; therefore, the l

hydrogen generation resulting from aluminum corrosion will decrease with the use of TSP. The corrosion of zinc and zinc-based pairis, which is highly dependent on

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i temperature, has been shown to be similar for 4 ne pH ranges of sodium hydroxide and TSP sprays. Elimination of the spray additive will have little net effect on

• hydrogen generation due to the corrosion of aluminum and zinc in the post-LOCA containment environment.

l The proposed change to a lower initial pH of 4.5 and a lower equilibrium pH of 7.5 to l '10.5 is expected to have no effect on equipment qualification or protective coating, j since both are currently analyzed for the more limiting condition of high pH for long L

term periods.-

i Offsite and Control Room thyroid doses were re-eva,#.ed considering the impact of l l

lower pH during the injection phase. The results are within 10 CFR 100 and l General Design Criteria (GDC) 19 limits.

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Enclos!cre 2 l i,

Joseph M. Farley Nuclear Plant i

! Elimination of Containment Spray Additive System l

Technical Specification Changes i

j 10 CFR 50.92 Evaluation i

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l h Enclosure 2 l-l Joseph M. Farley Nuclear Plant .

Elimination of Containment Spray Additive System Technical Specification Changes 3

l 10 CFR 50.92 Evaluation j

i Pursuant to 10 CFR 50.92, SNC has evaluated the proposed amendments and has l determined that operation of the facility in accordance with the proposed amendments '

would not involve a signific".d hazards consideration. The basis for this determination is as follows.

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1. The proposed change does not involve a significant increase in the probability or {

consequences of an acadent previously evaluated. The proposed change involves 1

replacement of concentrated NaOH injected via the containment spray system with l

[ trisodium phosphate (TSP) stored in the containment and dissolved in the sump l

! recirculation solution to maintain acceptable post accident spray / recirculation solution i chemistry. Deletion of the concentrated NaOH will eliminate a personnel hazard. The j pH control system functioris in response to an accident and does not involve or have

. any effect on any initiating event for any accident previously evaluated. - Operation under the proposed amendments will continue to ensure that iodine potentially l

released post-LOCA is retained in the sump solution, and resultant offsite and control room thyroid doses are within the limits of 10 CFR 100 and 10 CFR 50, Appendix A, l General Design Criterion 19. respectively.

! 2. The proposed change does not create the possibility of a new or different kind of

! accident from any accident previously evaluated. The deleted equipment is isolated

, from the remaining equipment by cut-and-capped piping, determinated and/or spared j cables; and interfaces are analyzed to ensure the remaining required equipment meets

, applicable original design requirements. The new equipment { TSP and baskets) is a

passive pH control system and is supported and analyzed to ensure there are no

adverse interfaces (e.g., pipe break, jet impingement, seismic) with existing equipment, system, or structures. I l

3. The proposed change does not involve a significant reduction in a margin of safety.

The slight change in recirculation solution pH maintains adequate protection against i chloride and caustic induced stress corrosion cracking on mechanical systems and

l. components, and maintains the capability of the solution to retain iodine, it does not 4

result in a change to the hydrogen generation analysis for containment. The increased mass inside containment will have no significant impact on post-accxient flood levels, recirculation solution boron concentration, or peak clad temperatures. No other

operating parameters for systems, structures, or components assumed to operate in the safety analysis are changed. The offsite and control room doses meet the limits of 4

10 CFR 100 and GDC 19, respectively. Because the trisodium phosphate is i nonvolatile and the baskets are protected with solid covers and are located slightly above the floor in the containment where access is strictly controlled, a surveillance interval of once per refueling outage provides assurance that the TSP will be available E2-1

Conclusion Based on the preceding anaiysis, SNC has determined that the proposed change to the Technical Specifications will not significantly increase the probability or consequences of an accident previously evaluated, create the possibility of a new or different kind of accident from any accident previously evaluated, or involve a significant reduction in a margin of safety. SNC therefore concludes that the proposed change meets the requirements of 10 CFR 50.92(c) and does not involve a significant hazards consideration.

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