ML20217B305

Application for Amend to Coc 7002 for Portsmouth GDP, Revising Technical Safety Requirements Sections 2.2.3.15 & 2.7.3.14 to Address,In Part,Cascade Situation in Which There Are Two Deposits That Exceed Safe Mass within Same Sys

ML20217B305
Person / Time
Site:	Portsmouth Gaseous Diffusion Plant
Issue date:	09/28/1999
From:	Adkins J UNITED STATES ENRICHMENT CORP. (USEC)
To:	Kane W NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
GDP-99-0177, NUDOCS 9910120204
Download: ML20217B305 (43)

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USEC A Global Energy Company JAMES N. ADKINs, JR.

Dir: (301) 564-3417 VICE PRESIDENT, PRODUCTION Fax: (301) 571-8279 September 28,1999 GDP 99-0177 Mr. William F. Kane Director, Office of Nuclear Material Safety and Safeguards Attention: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Portsmouth Gaseous Diffusion Plant (PORTS)

Docket No. 70-7002 Certificate Amendment Request-Technical Safety Requirements 2.2.3.15 and 2.7.3.14 Moderation Control

Dear Mr. Kane:

In accordance with 10 CFR 76.45, the United States Enrichment Corporation (USEC) hereby submits a request for amendment to the certificate ofcompliance for the Portsmouth, Ohio Gaseous Diffusion Plant (GDP). This certificate amendment request revises TSR Sections 2.2.3.15 and 2.7.3.14, Moderation Control, to address, in part, a Cascade situation in which there are two deposits that exceed a safe mass within the same system and only one deposit is physically being removed (e.g. cutting out a compressor).

The existing TSRs 2.2.3.15 and 2.7.3.14, do not clearly address the greater than safe mass deposit, which remains in the adjoining piping or equipment, and is now potentially exposed to atmospheric air. Other changes are proposed to improve the flow of the Required Actions and to clarify wording in the current TSRs.

Enclosure I contains the Oath and Affirmation. Enclosure 2 provides a detailed description and justification for the proposed changes to TSRs 2.2.3.15 and 2.7.3.14. Enclosure 3 provides a copy of the revised TSR pages.- In addition, Enclosure 3 contains a redline / strikeout version of the current TSRs which are provided to clearly illustrate the proposed changes.

Since this certificate amendment request is required to support continued plant operation, USEC requests NRC review and approval of this certificate amendment request as soon as possible. The amendment should become effective no later than 90 days from issuance.

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6903 Rockledge Drive, Bethesda, MD 20817-1818 Telephone 301-564-3200 Fax 301-564-3201 hnp://www.usec.com Offices in Livermore, CA Paducah, KY Ponsmouth, OH Washington, DC

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Mr. William F. Kane

- Septpmber 28,1999 '

GDP 99-0177, Page 2 DAny questions related to this subject should be directed to Mark Smith at (301) 564-3244 or Russell Wells at (301) 564-3245.

i Sincerely, mN. $$2.

3 James N. Adkins, Jr.

Vice President, Production

Enclosures:

l'.

Oath and Affirmation 2.

United States Enrichment Corporation (USEC), Certificate Amendment Request, Technical Safety Requirements 2.2.3.15 and 2.7.3.14, Moderation Control, Detailed Description of Change 3.-

Certificate Amendment Request, Portsmouth Gaseous Diffusion Plant, Letter GDP 99-0177, Removal / Insertion Instructions

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Robert Pierson (NRC)

Patrick lliland, NRC Region III Office Kenneth O'Brien, NRC Resident Inspector - PGDP David Ilartland, NRC Resident inspector - PORTS i

Randall M. DeVault (DOE) 1

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GDP 99-0177

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Page1of1 OATII AND AFFIRMATION

. I,-James N. Adkins, swear and affirm that I am Vice President, Production, of the United States Enrichment Corporation (USEC), that I am authorized by USEC to sign and file with the Nuclear

~ Regulatory Commission this Certificate Amendment Request for the Portsmouth Gaseous Diffusion Plant i

addressing revisions to the Moderation Control Technical Safety Requirements contained in USEC Letter i

GDP 99-0177,' that I am familiar with the contents thereof, and that the statements made and matters set forth therein are true and correct to the best of my knowledge, information, and belief.

%xb6Ly.

James N. Adkins, Jr.

On this 28th day of September,1999, the individual signing above personally appeared before me, is known by'me to be the person whose name is subscribed to within the instrument, and acknowledged that he executed the same for the purposes therein' contained.

In witness hereofI hereunto set my hand and official seal.

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f Ja' net Boo e, Notary Public State of Maryland, Montgomery County My commission expires Jee 23,2003 i

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E GDP 99-0177 Page1of19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change Specific TSR Section Changes The proposed change is to revise the Moderation Control Technical Safety Requirements (TSRs),

TSR 2.2.3.15 and TSR 2.7.3.14, to address a Cascade situation where two deposits that exceed a i

safe mass are located within the same system and only one of the deposits is physically being removed (e.g. cutting out a compressor). Existing TSRs 2.2.3.15 and 2.7.3.14 do not clearly address the deposit which remains in the adjoining piping or equipment and is potentially exposed to atmospheric air during activities associated with deposit remediation. Other changes are proposed to improve the flow of the Required Actions and to clarify tvording in the current TSRs. The specific changes to the TSRs are presented below. The description of these changes and the d

associated justification for the changes, apply to both TSRs 2.2.3.15 and 2.7.3.14, except where specifically noted.

To clearly illustrate the proposed changes a " redline / strikeout" version is included in Enclosure 3.

A summary of these changes follows:

1.

Condition A l

Condition Statement:

The statement was changed to reflect that chemical treatments are included in what is considered a fluorinating environment.

Required Actions:

A change was made to A.1 to clarify that the fluorinating environment is required for the deposit A.2 was changed to eliminate the requirement to determine the significance of a deposit discovered in the cascade.

A new A.4 was added to make a cross reference to the required surveillance.

Completion Time:

Added completion time associated with the new A.4.

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4 GDP 99-0177 Page 2 of 19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change 2.

Condition B Condition Statement:

A change was made to the statement to clarify that the deposit is not within the fluorinating environment and to eliminate repetitious information.

Required Actions:

B.1 was revised to include an exception to the requirement to have a dry cover gas blanket during maintenance associated with remediation of the deposit or as part of the equipment removal process and to initiate the corresponding surveillance.

B.2 was changed to remove "> safe mass".

.B.3 was added to reflect a second deposit remediation option which is to place the deposit in a fluorinating environment A note was added to re-affirm that Condition B is no longer applicable and is being exited.

l Completion Time:

The time interval for establishing the initial dry cover gas blanket was changed from 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> after obtaining a UF, negative to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The time frame for the ultimate deposit removal was increased from 180 days to 366 days and the time frame for re-establishing a fluorinating environment was set at 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

I 3.

Condition C Condition Statement, Required Actions, Completion Time:

A new condition was added to address the situation where there are at least two deposits greater than a safe mass in the same proximity, with only one of the deposits being physically removed. The required actions are specified to minimize deposit moderation while allowing for the necessary work evolutions to proceed.

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GDP 99-0177 Page 3 of 19 i

United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change 4.

Condition D Condition Statement:

This condition was originally condition C and has been revised to remove the criteria that the system is in a shutdown mode.

Required Actions:

D.1 was revised to clarify that the RCW pressure of concem is at the RCW condenser and to make cross reference to the required surveillance.

Completion Time:

The time for D.2 req tired to drain the RCW condenser has been increased from 16 to 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />.

5, Condition E Condition Statement, Required Actions, Completion Time:

A new condition was added to address those situations in which a required dry l

gas blanket is lost and must Le re-established.

6.

Surveillances Changes to the surveillances were made to improve their correlation to the revised TSR Conditions.

7.

Basis The Basis was revised to improve readability, flow and to provide supporting information for the actions and associated completion times.

The most significant issues addressed are the evaluation of safe mass at an H/U ratio of 4 t

and its relationship to the time required to fully hydrate a deposit. In addition, the principle that a deposit can be de-hydrated or dried out by exposure to a j

fluorinating environment is also discussed.

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GDP 99-0177 Page 4 of19 United States Enrichment Corporation (USEC)

Certificate Ameadment Request Cascade M;deration Control De, tailed Description of Change Justification In the gaseous diffusion process, significant quantities of gaseous uranium hexafluoride (UF ) are

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processed through thousands of feet of process piping and thousands of equipment components.

Considering a system of this size and complexity, it is r.nticipated that equipment failures of various j

types will lead to inleakage of air, and therefore moisture, into the cascade, particularly in those areas i

that operate at below atmospheric pressure. Since the diffusion process employs uranium in the form 1

of gaseous UF. which has a propensity for reacting with water to fomi solid uranium compounds, die formation of solid deposits within the system is expected. These deposits generally occur, in the case of airbome moisture, as a result of the following chemical reaction.

UF + 2H 0 - U0 F + 4HF 6

2 2 2 Moist air can enter the operating cascade through leaks in expansion joints, flanges, compressor seals, welds, etc.

The moisture in the air will react with UF to form intermediate uranium oxyfluoride compounds, HF and possibly UO F. When an excess of UF is present at a deposit 2 2 6

location, the reaction will form other intermediate uranium oxyfluoride compounds, such as U0F,

4 U 0 F, and U 0 F,, with associated HF, that are not fully hydrolyzed. Once these compounds are 236 33 formed, if UF is removed the intermediate compounds can react with any additional moisture to 6

form UO F and HF. The deposits will begin to accumulate on the piping, converter shell, barrier 2 2 tube-sheet and barrier etc. depending on the location of the inleakage. As leakage continues, deposits will contin 3 'o accumulate at a rate dependent on the inleakage rate, which is a factor of a number of variables including hole size, differential pressure at the hole and the relative humidity of the ambient air. These deposits cannot be hydrated while in operating equipment in the cascade.

The H/U ratio will remain low (i.e. H/Us 0.33, SAR C.I.2.3.2) and water will not be available to serve as a moderator as long as there is UF. gas flow that continues to react with the moisture and allows the relatively light HF gas to quickly move up the cascade and away from the deposit. There are two types of uranium deposits that exist in the cascade. The first type is UO F deposited in a 2 2 very difruse and reasonably uniform film on inner surfaces (Figure 1, less than an inch thick). The second type is large, localized deposithf UO F which are thicker and have less surface area (Figure 2 2 2, approx. 2.5 inches thick). Deposits are ultimately detected through routine surveys or by changes in cascade performance. The cascade is the " safest" place for a deposit where it is shielded from moderation control and human handling errors as assumed in SAR Section 4.1.1.2.2, Case C-10.

The cascade NCSA/NCSEs(References 8,9 & 10) place controls on the enrichment and moderation parameters to ensure, where applicable, double contingency (SAR Section 5.2) is met for the uranium

GDP 99-0177 Page 5 of19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change deposit condidon. The referenced NCSA/NCSEs support that double contingency against the loss of moderation control due to the inleakage ofliquid water into the cascade is met. The referenced NCSAs/NCSEs still contain the current TSR requirements and will be revised as appropriate to reflect the final results of this request. The loss of moderation control due to the exposure of a UO F2 deposit to moist air is determined to not meet double contingency for all deposits and is therefore the basis for these TSRs. It should be noted that a deposit whose mass is less than or equal to the

" safe mass" which is defined as 43.5% of the minimum fissionable mass for system conditions (enrichment, geometry, H/U, reflection, etc.), can not become critical and therefore does meet double contingency. TSRs are required for single contingent events, i.e. when a single event can directly result in a criticality. This single contingent event does not occur until there is a deposit that equals or exceeds the minimum critical mass at an H/U ratio of 4, for example: at 3%

enrichment the minimum fissionable mass equals 951 pounds of U0 F, at 5% enrichment the 2 2 minimum fissionable mass equals 513 pounds of U0 F and for a 10% enrichment it is 285 pounds 22 of U0 F. Correspondingly, the respective safe mass values at which the TSR controls are invoked, 22 are as follows: 414,223 and 124 pounds of U0 F -

2 2 The proposed changes to these TSRs and the associated justification are intended to bring the TSR controls into perspective with the analyzed criticality risk due to wet air exposure.

As long as a deposit exists in a fluorinating environment (UF., F. ClF or a mixture there of) there 2

3 is no potential for a U0 F deposit to become hydrated or moderated. In fact, the fluorinating gases 22

. will react with any water _ vapor and the hydrate to in essence " dry out" the UO F deposit.

2 2 Fluorinating gas treatment using F and/or CIF, sometimes referred to as " chemical treatment", has 2

3 been used as a means of drying equipment after exposure to atmospheric air and for removing deposits since the initial operation of the enrichment plants. These fluorinating agents react vigorously and preferentially with any moisture in the gas phase and then with any hydrates that are present. Once the moisture has been consumed, the fluorinating agents are then available to react with the U0 F deposit to convert it back to UF.. Therefore, the exposure of a deposit that contains 22 some moisture, introduced during those periods the deposit was open to the cell floor ambient air, to a fluorinating environment will remove the moisture from the deposit. Removal of the deposit by fluorination reduces the need to process solid uranium material through a liquid decontamination process, thereby eliminating the need for mechanically removing the deposit with the associated risks to workers and the increased risk of exposing the deposit to liquid water once removed from the cascade. The preferred method for remediation of a deposit is via chemical treatment.

The chemical reactions for fluorinating agents and moisture and/or UO F deposits have extremely 2 2 high equilibrium constants. Equilibrium constants indicate how favorable and fast a reaction will

GDP 99-0177 Page 6 of 19 United States Enrichment Corporation (USEC)

Certificate Amendment Request 1

Cascade Moderation Control 4

Detailed Description of Change proceed. The reactions of the fluorinating agents with moisture are shown below along with their equilibrium constants @ 77*F (Reference 6):

UF.<,3+ 2H 0,3 - U0 F < ) + 4HF(,3 Equilibrium Const. = 2.6x10 :

2 2c 22 2ClF <,3 + 2H 0<,3 - C10 F,,3 + CIF,,3 + 4HF,,3 Equilibrium Const. = 4.0x10" 3

2 2

3CIF (,3 + 3H 0(,3 - C10 F<,3 + 2ClF<,3 + 6HF,,3 Equilibrium Const. = 7.5x10"'

3 2

3 2F (a) + 2H 0(,3 - 0 (s) + 4HF,,, Equilibrium Const. = 1.7x10'"

2 2

2 The equilibrium constant is a function of the ratio of the concentration of reaction products to the concentration of the reactants present. A large equilibrium constant would mean that the reactants would form reaction products until the reactant with the lower concentration is essentially used up.

By maintaining an excess of fluorinating agents, it is possible to make water the lower concentration reactant and reduce the water concentration to levels equivalent to those experienced in the cascade by converting the water to HF. Equilibrium constants are therefore a means of evaluating how favorable a reaction is. The equilibrium constants for all the reactions shown above indicate that free water will be consumed. Based on the hygroscopic studies (References 4&5) and plant experience exposing the deposits to temperatures above the 77 F will improve the removal of water from the 1

deposits above that indicated by the equilibrium constants. Re-fluorination of a deposit will react directly with the moisture adsorbed on the deposit forcing additional dehydration of the deposit according to the following reactions:

UF,,3 + 1.25(U0 F *1.6H 0)<,3 - 2.25UO F <,3 + 4HF(,3 6

2 2 2

22 i2 Equilibrium Const. = 4.6x10 i

2ClF (,3 + 1.25(U0 F *l.6H 0)<,3 - C10 F(,3 + CIF(,3 + 4HF<,3 + 1.25UO F,,3 3

2 2 2

2 2 3 Equilibrium Const. = 7.0x10" i

F,3 + 1.25(UO F *1.6H 0)g" 1.25UO F,3 + 4HF<,3 + 0,3 3

22 2

23 3

L Equilibrium Const. = 2.0x10' I

L The high reactivity of these' fluorinating agents with free water vapor and hydrated uranium compounds suppons the argument that exposure of the deposit to a fluorinating agent will redry the deposit back to its original low H/U condition (operating cascade). Since the deposits under discussion have been formed under cascade operating conditions, they are essentially dry while they e

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GDP 99-0177 Page 7 of l9 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change l

remain in operating equipment where the UF continues to react with any moisture and the resultant l

HF flows up the cascade. Should such a deposit become exposed to ambient wet air outside of the cascade operating conditions and there is no fluorinating agent present, the surface of the deposit can begin to hydrate. However, due to the fact that during this period the deposit is going to be cycled through chemical treatments and/or dry gas buffering the hydration level remains on the surface.

l Even if the deposit was again exposed to UF such that the deposit could become larger, the UF.

would again react with the available moisture as it formed additional deposit material, thereby maintaining a dry deposit. No matter how many times this cycle is repeated the hydration of a deposit whether thick or thin would be confined to the immediate surface area and would be accessible to the fluorinating agents that would react with the water and produce a dry deposit. The use ofchemical treatments / fluorinating agents to transition back to a fluorinating environment poses no additional risk and supports the concept of resetting the " clock" or re-establishment of the time frame for which a deposit in a buffered environment can safely remain in the cascade. During the time a deposit is in the condition A and is exposed to UF. there is a potential for the deposit to become larger. The building NCSEs (References 8,9&l0) determined that it was non-credible for an unmoderated deposit, (i.e. dry mass), to become large enough to go critical in the cascade and that as long as the deposit was exposed to UF there was no potential for the deposit to become moderated. TSR surveillance 2.2.3.15.3/2.7.3.14.3 provides for the on going monitoring of the deposit to alert personnel to any potential structural or operational concerns. For the other conditions, UF is isolated from the deposit and will not become larger.

1 Studies (References 4 & 5) of the hygroscopic properties of uranyl fluoride (UO F ) have been 2

conducted and provide a basis for extending the time frames that a greater than safe mass deposit can be exposed to wet air without a significant increase in the probability of a criticality. It is known that U0 F will absorb moisture and form hydrates. The degree of hydration is a function of temperature, 2 2 the partial pressure of the water vapor and the deposit surface area available to be contacted with the moisture present in the gas phase. In the cascade fluorinating environment, the UF and other fluorinating gases present are much better desiccants than U0 F and will preferentially react with 2 2 any water that enters the process equipment. The hydrates range from 0 to 4 moles of H O per mole 2

of U0 F depending on the temperature and relative humidity (RH) of the ambient air.

2 2 Currespondingly the H/U ratio ranges from 0 to 8. The studies concluded that deposits when l

exposed to RH in the range of 50 to36 % formed stable hydrates that contained 1.6 to 2.0 moles of H O per mole of U0:F or H/U ratios of 3.2 to 4.0.

The test material did not experience i

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2 deliquescence until the RH was at 100%(entrained liquid droplets) and the temperature was below 95"F. The associated experiments revealed that deliquescence / hydration did not occur when the source of water was separated from the deposit in a static environment. Apparently, where the transfer of moisture must occur by pure gaseous diffusion, the diffusion rates are not sufficient to l

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I GDP 99-0177 Page 8 of 19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control De, tailed Description of Change hydrate the deposit. The existence of 100% RH and/or the presence of a constant moisture laden air flow over the deposit is not cmdible for a functioning gaseous diffusion facility. It should be noted that the associated experiment utilized a thin layer of fine U0 F powder which is not characteristic 2 2 of a cascade uranium deposit that exceeds a safe mass. Regardless of the deposit geometry, (e.g.

relatively thin slab or as a larger mass) the hydration occurs principally at the surface and diffuses inward. As the deposit is exposed to fluorinating agents and the water is reacted, there is a point reached when the water is consumed and the liberation of UF occurs. The liberation of UF. is therefore the indicator that a deposit is dry. The amount of time needed to dry a deposit is a function of the level of moderation the deposit has achieved prior to treatment. Therefore, Portsmouth procedures for chemical treatment contain drying criteria based on the concentration of CIF and/or 3

UF. During a chemical treatment, the concentration of these two materials are monitored every half-6 hour. The equipment is considered dry when the CIF concentration is no longer changing 3

significantly and is above a minimum level, or when UF. is being generated by reaction of the CIF 3 with the deposit indicating that the reaction of CIF with any moisture is complete. Operating I

3 experience has shown that drying is complete in the first few minutes after the CIF is introduced.

3 When returning equipment containing greater than safe mass deposits to Condition A, additional sampling is done after the chemical treatments are terminated. The samples are analyzed to ensure i

that there is residual fluorinating agent to maintain the system in a fluorinating environment. This conclusion is derived from the many cell treatments that have been performed. Relative humidity on the process building cell floor is normally considerably less than the RH available from the ambient outdoors. Cell floor temperatures are typically 20 to 80 degrees above the summer / winter outdoor temperatures. Relative humidities will decrease with a rise in temperature without any

. corresponding addition or removal of moisture. Based on local meteorological RH data, the cell floor humidity will be normally less than or equal to 60%. Should there be periods of time in which the cell floor relative humidity is above 60% it will not significantly alter the study findings nor will it invalidate the calculations discussed below(Reference 7) which assumed on an average a RH of 68% (maximum of 78%) through out the course of a year. It is therefore concluded that the maximum H/U ratio of a hydrated U0 F deposit in the cascade due to exposure to wet air is 4. It 2 2 is further evident that there is no potential for loss of moderation control of a cascade deposit which is less than the minimum critical mass at an H/U ratio of 4 from inleakage of atmospheric water vapor. In performing evaluations related to moderation control for wet air inleakage, while assuming a minimum critical mass at an H/U ratio of 4, the evaluation remains conservative since the minimum critical mass of a U0 F deposit at an H/U of 4 still assumes optimum geometry (sphere)

L 2 2 and full reflection ( l foot of water or equivaler+ encapsulation) which has never been observed for cascade deposits. SAR Section C.I.2.3.2 notes, that at an enrichment of 97.65%, it would require a 1140 pound dry mass of U0 F (H/Us 0.33) to achieve a criticality in a compressor which equates 22

.to a sphere 21 inches in diameter. A comparable sphere for a deposit with an enrichment of 10%

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GDP 99-0177 Page 9 of 19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change would be 45 inches in diameter (11,129 pound dry mass of U0 F (H/Us 0.33)). A sphere of this size 22 would not fit in a cascade compressor due to the physical size of the compressors.

Calculations have been performed (DAC-XSITE-El8892R14-NS-01 and 02 which are included in Reference 7) that indicate it would take 1.6 to 9.6 years, depending on cell size to moderate a deposit to the point of going critical by initially pressuring up the cell to atmospheric pressure by ambient outdoor air and allowing the cell to continue to " breath" due to changes in the barometric pressure.

The influx of moisture from the atmosphere into shutdown equipment is limited based on two mechanisms: 1)" breathing" of the cascade equipment, due to changes in atmospheric pressure and

2) molecular diffusion. The barometric pressure varies approximately 0.1 psi / day with the daily maximum variation in barometric pressure being 0.7 psi. The barometric variation during storms is on the order of 0.2-0.3 psi / day. The mass of the cascade, including the structure, provides a massive heat sink that prevents large short term temperature swings on the cell floor due to ambient outdoor temperatures and therefore will tend to maintain constant cell floor humidity.

Molecular diffusion, with no driving force other than the difference in water vapor pressure from the outside to the inside of the system / equipment, is an extremely slow process and is trivial in comparison to the " breathing" of the container with changes in atmospheric pressure, which in of itselfis not significant.

The studies (References 4 & 5) indicate that a container with a static atmosphere and 100% RH did not cause deliquescence of U0 F as long as the U0 F was physically separated from the source of 2 2 2 2 water. This indicates that the diffusion of water in a static atmosphere does not provide an adequate driving force to hydrate a deposit. At the Oak Ridge Gaseous Diffusion Plant cascade equipment in the K-29 Building was shut down in 1985 (Reference 11). Since shutdown, the process system remained essentially closed and unbuffered (buffering removed in 1991) until the start of the deposit removal project in 1997. However, since discontinuation of enrichment operations. personnel have on occasion removed some process equipme.it items for shipment to other enrichment facilities.

These equipment removal activities created large openings in the process system which having since been welded closed, allowed moisture laden air free access to the deposits. During the 12 years the equipment was shutdown daily fluctuations, in temperature and pressure resulted in a very limited exchange of ambient air into the process system. NDA surveys identified 32 deposits with greater than 550 grams "U with a potential enrichment of 12.5% based on historic data. A 1995 analysis 2

also concluded that several of the K-29 deposits contained a mass greater than the critical mass quantity at a H/U ratio of four. This is significant because UO F deposits that have been exposed 2 2 to ambient air are theoretically expected to absorb moisture up to approximately this level of moderation.- Visual observations of the deposits to be removed indicated that they were hard and

)

GDP 99-0177 Page 10 of 19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change required mechanical methods (i.e. shovels, scrapers, etc.) to physically remove the deposits (Figure 3). Deposit hardness of this degree is consistent with the criticality risk assessment which assumed a maximum H/U of 4.

During the removal process it was also identified that in some cases HF would still evolve from the deposit when exposed to ambient air. This is indicative of a deposit that contained intermediate oxyfluoride compounds which have not fully reacted (hydrated) by the exposure to moisture while in the cascade. The same basic K-29 findings were evident in the deposit removal activity for the K-25 HEU equipment that had experienced numerous (20 to 30) years of uncontrolled exposure (i.e. equipment removed without coverings) to atmospheric conditions at the Oak Ridge Gaseous Diffusion Plant (Reference 13). These openings allowed the unimpeded j

diffusion of moist air through the process equipment. As expected, personnel removing additional equipment did not witness any moisture collecting in low points of the process equipment.

Furthermore, examination of some deposits revealed that they were not moist but rather the surface of the deposits had hardened, significantly limiting the deposits' solubility or receptivity to hydration. As described, it takes on the order of years for water molecules to contact the U0 F 2 2 surface area to form a hydrated deposit. The same experience wot.ld indicate that the penetration of the water molecules into the deposit is self limiting from which it can be concluded that i

deliquescence is not credible.

The hydration calculations (Reference 7) are believed to be extremely conservative for the following reasons:

1.

The calculations assume RHs associated with the outdoor ambient air and do not consider the reduction in RH due to cell floor heating which is a critical factor in the hydration of a deposit.

2.

The calculations assume that none of the moisture that enters the cell is consumed by the significant barrier area which will adsorb moisture.

3.

An additional conservatism is that deposits of this size (greater than minimum critical mass at an H/U of 4) are very unlikely to be present in a compact (i.e. optimum geometry) orientation. 'IK most cases visually inspected to date, such uranyl fluoride deposits have been present in a thin layer (less than 1 inch thick) spread over the interior l

surfaces of the compressor and converter. In this orientation, it would require significantly more mass to present a minimum critical mass even if moderated to an H/U cf 4. In those cases where the deposit is in the form of a solid mass, the surface area exposed or available to be hydrated is significantly reduced. Correspondingly, the hydration by exposure to wet air of the total deposit, that was originally shutdown in a l

GDP 99-0177 Page 11 of19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control j

Detailed Description of Change fluorinating environment, to a level that could support a criticality would require many years for the reasons previously discussed.

In June 1990, two cylinders in the depleted UF. cylinder storage yards at Portsmouth were discovered to have holes in their walls at the valve-end stiffening ring at a point below the level of the gas-solid interface of the UF (Reference 12). The cylinder with 6

the larger hole, which extended under the stiffening ring, was stacked in a top row for 13 years. The cylinder with the smaller hole had been stacked in a bottom row for 4 years.

Following the initial mechanical failures, reaction of UF.

with the ambient

{

atmosphere (rain and snow) led to the formation of an acid solution containing HF and i

U0 F and ultimately, to a protective salt layer composed of UF, and iron fh.orides. Slow 2 2 seepage of the acid solution from below the UF layer gradually corroded and extended 4

the hole surfaces, such that the relative sizes of the openings correlated with the total-time that the respective cylinders had been exposed to the elements. For the referenced 13 year old cylinder, the depth of the UF hydrate layer was about 4 in. And the depth 4

of the yellow hexavalent uranium oxy-fluoride layer was in excess of 8 in. Observations of the damaged depleted UF cylinders in which the UF was exposed to ambient 6

6 weather (rain, snow, large temperature variations, etc.) concluded that it would take perhaps as much as 30 years to hydrolyze the cylinder corents which further supports the premise that hydration and associated reactions of solid deposits, even under the most extreme moderation conditions, is a very slow process.

4.

NDA measurements for determining deposit size and enrichment are ( onservative. This is inpart due to the addition of a 50% uncertainty factor to the fimal deposit size. PORTS utilizes the same NDA methods and equipment as did the deposit removal project and therefore would expect the same kind of experience. Plant experience at PORTS and documentation from the K-29 removal project (Reference 11) as illustrated below would indicate that the NDA measurements without the 50% factor are also very conservative.

Ex.

NDA deposit estimate was 1,190 kg U @ 3.3%. Actual amount of material removed was 450.1 Kg U @ 3.0% with 43.3 Kg U remaining in the pipe for a total quantity of 493.4 Kg U.

This represents an approximate 58% over statement of deposit size.

y:

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l GDP 99-0177 l

Page 12 of19 l

l United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control

' Detailed Description of Change Ex.

NDA deposit estimate was 773 kg U @ 2.0%. Actual amount of material l

removed was 370.6 kg U @ an ave.1.87% with 56.4 kg U remaining in the pipe for a total quantity of 427.1 Kb U.

This represents an approximate 44.7% over statement of deposit size.

Ex.

NDA deposit estimate was 209 Kg U @ 3.5%. Actual amount of material removed was 84.4 kg U @ an ave. 2.95% with 14.05 kg U remaining in the pipe for a total quantity of 98.5 Kg U. This represents an cpproximate 52.8% over statement of deposit size.

6 The extension of the removal time (from 180 days to 366 days) fer cascade equipment containing a deposit greater than safe mass in a non-fluorinating or buffered atmosphere will provide the i

freedom to effectively and efficiently manage the deposit removal. Actions necessary for the plant to remain in compliance with the current moderation control TSR requirements take precedent over those actions that would result in the most optimum removal of deposits. The additional time I

provides the opportunity to consolidate necessary resources to reduce the overall number of deposits in a shorter time frame.

The chemical treatment process for the remediation of deposits is the safest and most overall efficient means for removal of deposits. The chemical treatment process prevents the exposure of

. personnel to potentially harmfullevels of airbome uranium HF vapons, the spread of contamination, j

and reduces the amount of uranium waste associated with the physical removal option. The J

limitation associated with chemical treatment is the potentially extended deposit removal time over f

- that associated with the physical removal process due to slow reaction rates, especially when i

- utilizing a " static" treatment and-competition for equipment used in the treatment process (e.g.,

evacuation booster stations (EBS), surge drums, monitoring resources, etc.) between treatment l'

locations.

As of 6/14/99 there were 11 cascade deposits that fall under the moderation control TSR. Seven of f

the deposits are in the operating cascade and therefore are exposed to a continual UF fluorinating I

6 environment. As noted in the existing TSR, even though these deposits are subject to surveillance requirements, they do not pose a significant criticality risk and as such do not have a specified

)

removal time frame. The remaining four deposits fall under TSR LCO Condition B and are subject to the 180 day limitation. To demonstrate that additional time can result in reducing the overall I

number of deposits in a shorter time frame, a specific scenario will be sited. The four deposits are i

located in cells which were to enter a fluorinating environment on or before 7/11/99 (2 cells),

7/26/99 and 8/6/99 or the deposits physically removed. While these deposits can be maintained in l

'.t

E' e

GDP 99-0177 Page 13 of19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change accordance with the current TSR, it is not possible to make significant strides in reducing the total deposit mass due to the limitations previously stated. The simultaneous managing of four deposits in compliance with the current TSR, results in the repetitive transfer of resources (e.g., operators, sampling / monitoring equipment, maintenance, valving lineup changes to EBS, surge drurr$

fluorinating agents, dry air, etc.) between deposit locations for the purpose of ensuring they continue to remain in compliance with the TSR criteria addressing buffering and fluorinating environment.

Equipment resources are limited..A more effective plan, based on this scenario, would be to dedicate these resources to chemically treat one cell, to below safe mass while maintaining the other three offstream deposits in a buffered condition until the deposits being treated can be remediated to below a safe mass. The specific cell being discussed, in which there is also the opportunity to simultaneously treat two adjacent onstream deposits, is offstream and isolated by the closure ofits 4 primary block valves. The adjacent onstream deposits discussed are located in the piping that connects the cascade cells to each other. In this instance, by altering the isolation valving all three deposits can be included in the chemical treatment. Once completed, the next deposit for treatment would be selected and processed until completion (i.e., remediated to below a safe mass), etc. The additional 180 days as applied to this scenario would allow the demand on chemical treatment resources to be spread out and thereby result in more deposit material removed in a shorter time frame.

The time in which a cascade deposit can be exposed to cell floor ambient air can be increased without compromising nuclear safety due to the close correlation between the theoretical / laboratory reaction kinetics associated with the UO F,,/H 0 reaction and field observations which define a safety 2

2

. margin of well over one year. Also keeping in mind that the exposure to ambient cell floor air is only during those periods (not continuous) in which. work is being performed to expedite the ultimate elimination of the deposit. Administrative controls exist and will remain in place that should liquid water be present (e.g. sprinklers, RCW, roofleak, etc.) openings to a deposit above a safe mass will be covered immediately. The proposed change wil.' not significantly reduce the safety margin as defined in the bases for TSRs 2.2.3.15/2.7.3.14. The existing basis statements already acknowledge that moderation control is not a concern until the cell / system that contains the greater than safe mass

. deposit is taken offstream and evacuated ofits UF. Tne basis goes on to state that there are analyses 6

that demonstrate that " breathing" of a cell, (i.e. wet air exposure), will not significantly affect deposit moderation even over a period much longer than 180 days.

The residual risk for criticality ofleaving a deposit in place in a fluorinating environment is very l

low. Leaving the deposit in place in a fluorinating environment indefinitely is no greater risk than j

the present TSR criteria. The presence of a fluorinating environment ensures that the deposit 4

remains unmoderated even with some inleakage of moist air. Therefore, the risk of criticality is no greater than when the deposit was initially created because the H/U ratio remains very low. The j

l i

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1:

1 GDP 99-0177

~

Page 14 of 19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change equipment containing the deposit is monitored at a frequency that ensures that any change in the j

deposit environment will be detected in a timely manner and the appropriate actions taken. The potential failure of the containment is within the SAR accident analysis assumptions.

1 The residual risk for treating deposits that have been left in place for an indefinite period of time is no greater than treatment of a deposit shortly after its formation. For deposits being treated, the cascade equipment is isolated from the operating enrichment cascade during treatment. The only residual risk would be an unexpected breach of the equipment. In such an unlikely event, the inleakage of moist air would react with the fluorinating agents present in the equipment and would preserve a " dry" environment. The subsequent breathing of the equipment would take a very long time (on the order of 1.6 years to nine years depending on the size of the deposit and the equipment volume) to moderate a deposit to an H/U of 4. Cell treatment procedures are carefully controlled to prevent an exothermic reaction that could breach the cell containment. In the event of such a reaction, the heat of reaction would keep the deposit completely dry and the moderation potential from wet air inleakage would be as described above. An activation of a sprinkler system from an exothermic reaction is very unlikely since the cell coolant inventory is removed prior to such treatments and the reaction of fluorinating agents with aluminum within the cell is self-limiting.

For those deposits present in cascade equipment that is part of the operating cascade, the residual risk

' *ho very Sw. The gaseous diffusion process tolerates the inleakage of small amounts of moist Ar. The process gas flowing through the equipment prevents moisture from hydrolyzing deposits by reacting with the moisture to produce HF, which will be swept up the cascade keeping any deposits unmoderated. This can result in some growth of the deposit (hence the periodic deposit monitoring requirement in the TSR); however, the deposit will remain dry. Massive inleakage of wet air is handled procedurally to isolate the equipment with the leak as quickly as possible to protect the rest of the operating cascade. In the event of an inleakage of wet air that would fill the cell volumes of a number of cells, the amount of moisture involved in filling a cell up to atmospheric pressure would not be enough to moderate a dry deposit with a mass equal to a minimum critical mass at an H/U of 4 to an H/U of 4. Assuming an initial cell pressure of 5 psia and a moisture content of 0.5 grams H 0, inleakage of" wet" air to a 000 cell would introduce approximately 30 lbs.

2 H O (approximately 100 lbs. is required to moderate a deposit at 3% emichment to an H/U of 4);

2 a 0 or 00 cell would receive 12-13 lbs. of H,0 (approximately 62 lbs. is required to moderate a deposit of 5% enrichment to an H/U of 4); a "27" or "25" size cell would receive about 1.8 to 2.4 lbs. of H O (approximately 47 lbs. is required to moderate a deposit with an enrichment of 7% to an 2

H/U of 4). In addition the minimum critical mass value assumes a spherical geometry and full reflection (i.e., I foot of water or equivalent encapsulation). As such, there is no potential to moderate a deposit, that has been in a fluorinating environment, to a safety significant level do a single massive inleakage of atmospheric air.

l

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1 GDP 99-0177 Page 15 of 19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change The potential of an exothermic reaction resulting in a criticality is addressed in the SAR Section 4.1.1.2. In onstream equipment, such a reaction is unlikely to directly affect a previously existing i

deposit greater than safe mass. In order for such large deposits to be formed and continued operation of enrichment cell equipment still be possible, the deposit must be in connecting piping rather than in cell stages. As such, an exothermic reaction, which would be initiated in rotating equipment

. (stage compressors), would not likely impact such deposits dicetly (e.g. by breaching containment at the deposit location). An exothermic reaction would retivate the sprinkler systems only if a coolant system breach occurs with an associated reaction involving decomposition of the coolant.

In such cases, the coolant would expand and

ve the process gas away from the coolant leak

)

location and will tend to reduce the inleakage of atmospheric air. As a result, the presence of deposits in fluorinating environments in operating equipment does not contribute to the overall risk of a criticality in the cascade due to potential exothermic reactions.

Additional TSR Change Ration

• i 1.

Condition A he wording in the Condition A was revised to reflect that a anorinating environment includes chemical treatments which utilize fluorinating agents CIF /F -

3 2 2.

Required Action A.1 This change adds "for the deposit" to the required action to clarify l

and support the condition statement.

l 3.

Required Action A.2 The need to determine e9 Mposit's significance at the point of discovery has been eli-

11. The significance of a deposit in -

the cascade has alte en evaluated from an " envelope" r

perspective in the SAR cality scenarios (Reference 1) and the appropriate site NCSA/NCSE(s). The commensurate actions j

from the evaluations are reflected in the Moderation Control i

l TSRs.

4.

Required Action A.4 The surveillance action was added to provide a cross reference action to the required TSR surveillance which supports the developed plan of action. The completion time is consistent with the surveillance frequency.

l E.

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GDP 99-0177 Page 16 of 19 United States Enrichment Corporation (USEC)

L Certificate Amendment Request Cascade Moderation Control Detailed Description of Change 1

5.

Condition B The reference to "with the deposit", "in Mode VI", and " chemical treatments are not in pmgress" are redundant information to the condition "U0 F > safe mass not in a fluorinating environment" 22 and are removed.

6.

Required Action B.1 -

The requirement to have a dry cover gas blanket when the deposit is not in a fluorinating environment is still maintained. The change is intended to reflect that it is not feasible to perform the functions necessary to remediate a deposit and still maintain the dry cover gas blanket at all times. The dry cover gas blanket requirements minimize the time available for wet air inleakage while taking into consideration the time that is required to conduct transition activities associated with deposit remediation, such as equipment removal, leakrates, evacuations, cell startup, etc..

7.

Required Action B.2

"> safe mass" was removed due to its redundancy to the LCO statement.

8.

Required Action B.3 -

This new action reflects one of three options that exist in regard to the handling of a deposit. The three basic options are to 1) maintain or place the deposit in a fluorinating environment 2) buffer the deposit and 3) physically remove the deposit. It should be noted that a fluorinating environment can also include the performance of chemical treatments which is the optimal method for remediation of a deposit.

9.-

Required Action Note This action re-enforces that upon completion of action B.3, the condition that would then apply to the deposit is condition A.

10. Condition B -

The referenced (8,9,10) NCSA/NCSE(s) for remediation of Completion Times deposits recognize that it is impossible to prevent certain levels of wet air inleakage while removing equipment from the cascade or performing maintenance in which the containment boundary of the cascade is breached. This inleakage is minimized to the l

greatest extent possible. 'l.chnical studies and Engineering L

evaluations as discussed in the amendmentjustification, have I

c GDP 99-0177 Page 17 of 19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control De, tailed Description of Change dea rmined that minimal amounts of water via moist-air inleakage will be introduced during periods when the buffer is not maintained, even during extended periods of time (e.g.,1.6 or longer years). This amount of moist air is less than required to cause a criticality, even in a large deposit. Furthennore, the re-application of a fluorinating environment or a dry cover gas blanket tends to have a drying effect on the deposit and will retum the deposit's H/U ratio to its originally low value.

11. Condition C This new condition was added to address the situation where there are at least two deposits greater than a safe mass in the same proximity with only one of the deposits being physically removed.

The specific actions are designed to ensure the deposits are not moderated while at the same time allowing for necessary maintenance work to proceed. These changes recognize that the transition from deposit conditions of either a fluorinating environment or a dry cover gas blanket to the performance of chemical treatments (which can include the re-installation of j

removed equipment necessary to support the chemical treatment process) is not instantaneous but requires actions which temporarily discontinue the dry cover gas blanket and allows inleakage of atmospheric air due to

" breathing". The performance of these transitional actions is essential to the ultimate removal of the greater than safe mass deposit.

As discussed in item 10 of thejustification section, this inleakage is not significant from a nuclear criticality safety perspective.

12. Condition D This condition, which was condition C in the existing TSRs, removed " system is in a shutdown mode" which has no significance to the moderation control issue of providing added assurance that liquid water could not leak into the deposit area from the RCW condenser. The addition of "syst< 7" only provides a more descriptive adjective for the coolant pressure.

l

13. Required Action D.1 Based on the intent of Condition D Mais change to add

" condenser" serves to clarify which RCW pressure is essential to perfonn the action.

At PORTS, the cascade building RCW

[

pressure is read and then the head loss to the RCW condenser is

r 1

GDP 99-0177 Page 18 of 19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change s'ubtracted to obtain the condenser RCW pressure. The added surveillance reference increases the assurance level that the required TSR surveillance will be performed as required.

14. Condition D.2 The change from 16 to 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> was made to provide the time Completion Times necessary to coordinate and complete the draining effort. The additional 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> will not invalidate the NCSA/NCSE(s) that support double contingency for the prevention of liquid RCW entering a cell via the condenser.

15. Condition E This condition was added to address the situation in which a bufTer is not applied or re-applied as required. The E.1 action and the completion time are consistent with the existing surveillances 2.2.3.15.2/2.7.3.14.2 which address ensuring a proper buffer on a shiftly basis (TSR section 1.3, Use and Application).

(

16. SR 2.2.3.15.1 The surveillance was changed to provide a more explicit cross l

& 2.7.3.14.1 reference to the related Condition D and Required Actions.

l

17. SR 2.2.3.15.2 The change to this surveillance frequency is madeo cross tie the i

l

& 2.7.3.14.2 surveillance to the appropriate Condltion B or C, where this surveillance is invoked.

18. SR 2.2.3.15.3 -

The change to this surveillance frequency is made to cross tie the

& 2.7.3.14.3 surveillance tot he appropriate Condition A, where this surveillance is invoked. Also the surveillance was reworded to j-eliminate redundant wording which did not change the j

surveillance intent.

19. Basis Changes to the Basis were editorial and restructuring in nature.

The justification associated with technical issues discussed in the Basis to support TSR changes can be found in the corresponding TSR amendment justification section.

GDP 99-0177 Page 19 of 19 United States Enrichment Corporation (USEC)

Certificate Amendment Request Cascade Moderation Control Detailed Description of Change References 1.

Application for United States Nuclear Regulatory Commission Certification, P. 2 mouth Gaseous Diffusion Plant, Safety Analysis Report, Chapter 4, Sections 4.1.1.2.1,4.1.1.2.2, 4.1.1.2.3.4, C.I.2.2.1, C.I.2.3.2, Cases C-3A, C-3B, C-5, C-10, C-12, C-16.

2.

Application for United States Nuclear Regulatory Commission Certification, Portsmouth

. Gaseous Diffusion Plant, Safety Analysis Report, Chapter 5.2, Nuclear Criticality Safety.

3.

Application for United States Nuclear Regulatory Commission Certification, Portsmouth Gaseous Diffusion Plant, Technical Safety Requirements, TSRs 2.2.3.15 & 2.7.3.14, Moderation Control.

4.

Thermodynamic Properties of the HF-H 0-U0 F: System, K/TSO-9, Part 1, The U0 F -H O 2

2 22 2 System.

5.

Investigation of Hygroscopic Properties of Uranyl Fluoride, KY/L-1699.

6.

Engineering Evaluation No. EVAL-X800-PP-001, Rev.1, July 8,1998.

7.

Engineering Evaluation No. EVAL-XSITE-E1892R14-NS-01, Rev.0, July 13,1998.

8.

NCSA-0333,,015.A03 & NCSE-0333_015.E03, Cascade Operations in the X-333 Building.

9.

NCSA-0330_004.A03 & NCSE-0330_004.E03, Cascade Operations in the X-330 Building.

10. NCSA-0326_013.A06 & NCSE-0326_013.E05, Cascade Operations in the X-326 Building.

I 1.

Project Completion Report for the Deposit Removal Project in the K-29 Building, East Tennessee Technology Park, Oak Ridge, Tennessee

12. Investigation of Breached Depleted UF. Cylinders, ORNL/FM-11988

13. Preliminary Probabilistic Criticality Assessment OfSelected Low-Enriched Uranium Facilities At The Oak Ridge K-25 Site, K/D-6048

(-

L GDP99-0177 Page1of21 l

C,ertificate Amendment Request j

Portsmouth Gaseous Diffusion Plant Letter GDP99-0177 Removal / Insertion Instructions Remove Page Insert Page l

VOLUME 4 TSR 2.23.15 TSR 2.23.15 Pages 2.2-27 through 2.2-30 Pages 2.2-27 through 2.2-30a TSR 2.73.14 TSR 2.73.14 Pages 2.7-23 through 2.7-25 Pages 2.7-23 through 2.7-25b l

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1 l

1

l, TSR-PORTS PROPOSED September 28,1999 j

RAC97X042?

1.

l' SECTION 2.2 SPECIFIC TSRs FOR X-330 AND X-333 FACILITIES i

2.2.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.2.3.15 Moderation Control Applicability: Cascade Operational Modes I, II, III, IV, V, VI J

LCO: Moderation Control shall he maintained when the UO F mass is > safe mass.

2 2 ACTIONS:

Note: TSR 1.6.2.2(d) does not apply Condition Required Actions Completion Time A.

UO F deposit > safe mass in a A. I Contmue to maintain a fluormaung Immediately 2

fluoruuting (including chemical envirorumnt for the deposit treanneut) environment.

AND A.2 Inicate actions to determine the cause of immediately deposit.

AND A.3 Establish and document a plan of action 30 days AND A4 Initiate SR 2.2.3.15.3 40 Days B.

UO F deposit > safe mass with the B.l.1 Estabhsh a dry cover gas blanket at 14 Within 72 Hours after 3 3 deposit not in a fluorinating psia except when performing maintenance entering Mode VI environment.

or operational activities associated with remediation of the deposit. equipment removal or leak repair.

AND B. I.2 Initiate SR 2.2.3.15.2 12 Hours AND B.2 Remove equipment containing the UQF 366 days I

3 deposit from the cascade OR Note:

Upon completion of B.3, Condition A is re-entered.

B.3 Initiate re-fluorination activities Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of removal of dry cover gas blanket C.

Installed equipment contaimng known C.1 Apply TSR 2.2.3.16 as appropriate to Immediately or previously unknown deposit of equipment removed UO F, deposit > safe mass opened to AND 2

atmosphere.

C.2 Cover opening (s) that expose UQF, immediately after deposit to atmosphere when maintenance determuung acceptable evolunons are ad impacting equipment.

UF,/HF conditions AND C.3 Maintain dry cover gas blanket a 14 psia Withm 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after when cascade system maintenance completmg REQUIRED evolutions are na impactmg equipment.

ACTION C.2 AND Note:

Upon completion C.4, Condition B is re-entered.

C.4 Maintain dry cover gas blanket i 14 psia Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after following completion of cascade system completing system maintenance on affected equipment and maintenance UO,F deposit is not in a nuorinating environment.

2.2-27 l

TSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.2 SPECIFIC TSRs FOR X-330 AND X-333 FACILITIES j

2.2.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.2.3.15 Moderation Control (continued) m Condition Required Actions Completion Time D.

Uo F deposit > safe mass, not in a D.I.!

Increase coolant system pressure to >

4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> fluorinating environment and coolant RCW condenser pressure.

system pressure s RCW condenser AND pressure.

D.I.2 Initiate sR 2.2.3.15.1 12 Ilours OR D.2 Drain RCW from coolant condenser 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> l

E.

Uo2F, deposis > safe mass with the E.1 Re-establish a dry cover gas blanket = 14 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> deposit not in a fluorinating psia.

environment and required dry cover gas blanket < 14 psia.

SURVEILLANCE REQUIREMENTS:

Frequency Surveillance Each shift when not in a fluorinating SR 2.2.3.15.1 Verify coolant system l

environment, deposit > safe mass and pressure >RCW condenser pressure.

l RCW not drained Each shift when dry cover gas blanket is SR 2.2.3.15.2 Monitor the system pressure l

required by Condition B or C and adjust pressure to a 14 psia.

l Quarterly when in Condition A SR 2.2.3.15.3 Monitor size of the deposit.

l I

Quarterly SR 2.2.3.15.4 Perform routine qualitative radiation surveys of bypass housings to check for depasits and initiate "NDA" quantitative measurements based on "radiatica reading trending" i

2.2-28

iSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.2 SPECIFIC TSRs FOR X-330 AND X-333 FACILITIES 2.2.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.2.3.15 Moderation Control (continued)

BASIS:

As used in this TSR, the term " safe mass" is defined as being 43.5% of the minimum fissionable l

mass for system conditions (enrichment, geometry, H/U, reflection, etc.). Cascade deposits of l

UO F (and deposits of other compounds resulting from wet air inleakage) and freeze-out of UF.

I 22 are an expected result of normal operation. It is considered non-credible for a dry criticality to l

occur in the Cascade. Therefore, for a freeze-out condition, criticality would not result and the l

UF freeze-out may be remediated at the discretion of the operating organization. Any deposit that l

6 has a uranium mase less than the "always" safe mass (i.e. optimally moderated material) and may l

be remediated at the discretion of the operating organization. In regard to those situations in l

which a loss of moderation control could result in criticality, it has been determined that NCSA l

specified controls provide double contingency against the inleakage of liquid water into the l

cascade. Based on additional technical evaluations it is not possible to hydrate a deposit of uranyl l

fluoride above a H/U ratio of 4 by exposure to ambient air within the process buildings.

l Therefore, there is no potential for criticality when a cascade deposit is less than the safe mass at l

a H/U ratio of 4 due to exposure to atmospheric water vapor in the ambient process building air.

l l

UF., F, and CIF react with available water more readily than UOF absorbs water. For l

2 3

2 2 instance, water entering onstream cascade equipment will preferentially react with UF. to form l

more UO F rather than react with UQF to form hydrates (moderated forms) of UO F. HF gas l

22 2

2 2 formed as a byproduct of the water-UF reaction cannot liquefy to moderate a deposit at the l

6 pressures encountered in the cascade. A UO F deposit cannot become moderated if it is being l

2 2 continuously fluorinated and moderation is not a concern until the equipment is taken off-stream l

and evacuated of UF. Continued fluorination of the deposit provides nuclear criticality safety by l

preventing moderation of the deposit.

l l

Chemical' treatment processes which involve the addition of ClF and/or F (i.e. fluorinating l

3 3

agents) provide the same level of moderation control as when the deposit is exposed to UF.

l 6

Fluorinating gas treatments have been used as a means of drying out equipment after exposure to l

atmospheric air and for removing / reducing uranium deposits since the enrichment plants were l

placed into service. It has been demonstrated that these fluorinating agents will react vigorously l

and preferentially with any available moisture. The presence of excess fluorinating agents will l

not only prevent further hydration of a deposit but will over time effectively remove any free l

moisture and dehydrate the exposed deposit to an H/U ratio as low as when the deposit was l

exposed to the UF. process. In addition, use of fluorinating agents will convert UQF deposits l

2 to UF, thereby reducing the deposit mass. Repeated use of the fluorinating agents (i.e. chemical l

6 treatment) will proceed to reduce / eliminate the deposit which is the safest condition. Therefore.

l a deposit that has been hydrated to some extent due to " breathing" or during the times necessary l

to expose the deposit to atmosphere when maintenance functions are performed can be dehydrated l

2.2-29

TSR-PORTS PROPOSED September 28,1999 RAC97X0422 f'

SECTION 2.2 SPECIFIC TSRs FOR X-330 AND X-333 FACILITIES l

2.2.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.2.3.15 Moderation Control (continued) by the presence of a fluorinating agent. The sustained liberation of UF from the deposit during l

6 a chemical treatment is the proven indicator that the deposit has been dehydrated. Once a deposit l

has been dehydrated, re-entry into Condition B establishes a new initiating time for required l

actions. After having been exposed to a fluorinating environment in which there has been

.e I

sustained liberation of UF, the re-entry to the buffered condition for one year will not decrease l

the assumed safety margin for this condition. Chemical treatment activities as discussed in this l

LCO may include preparation activities such as evacuation, leakrate, seal checks and cell startup.

l l

UO F deposits in onstream operating equipment are not a nuclear criticality safety concern due l

2 2 to continuous fluorination of the deposit. Over time, sustained or large wet air inleakage in l

operating equipment (active process area) will readily announce itself in the form of changing l

motor loads, compressor surging, line recorder readings, stage control valve positions, A-suction l

pressures, etc.. Additionally, deposit formation in operating equipmGd will be dispersed by the l

gas flow. This dispersion of UO F can occur on the inside of process piping, across barrier l

2 2 tubing, on cooler fins and inside compressors on the rotor and stator. Due to this dispersion, the l

formation of deposits in unsafe geometries in active process areas where there is UF gas flow is l

not likely, given the above indicators. However, the above mentioned indicators and continuous l

gas flow are not always available for wet air inleakage in bypass / auxiliary piping, expansion joints l

and valves (inactive process areas). Operational experience indicates that quarterly surveillances l

by NDA methods for UO F deposits in inactive process areas is appropriate for early detection l

2 2 and prudent remediation of the deposit. Follow up surveys are conducted to assure that the deposit l

does not become sufficiently large to become an operational problem or a cascade structural l

concern.

l j

I Routine NDA surveillance methods are oflimited value, with respect to quantification of deposit l

size, for active process areas which include compressors, converters, process gas coolers and l

freezer /sublimers. However, sustained or large wet air inleakage in active process areas will l

readily announce itself which will prompt corrective actions by operating personnel. Also, the l

1 formation of UO F deposits in unsafe geometries in active process areas is not likely given the l

2 2 l

above corrective actions. The limited ability to hydrate a deposit in in-place process equipment l

assures that these deposits will remain critically safe after shutdown. Thus the primary concern l

for the formation of UO F deposits in unsafe geometries in operating equipment is if this l

2 equipment trips or is shutdown while containing UF and massive wet air inleakage occurs. In thir l

i event, the wet air inleakage will be obvious from the equipment leak rate which will prompt l

l corrective actions to limit the size of the deposit.

l l

l For shutdown equipment, moderation control can be provided by a fluorinating environment or l

by a dry cover gas (plant air or nitrogen) blanket over the deposit even if significant wet air l

inleakage has occurred. Once a system has been isolated from the cascade and filled to a 14 psia l

2.2-30

T' ~ ~

~

TSR-PORTS PROPOSED September 28,1999 RAC97X0422

\\

SECTION 2.2 SPECIFIC TSRs FOR X-530 AND X-333 FACILITIES I

l 2.2.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR l

OPERATION, SURVEILLANCES l

i l

2.2.3.15 Moderation Control (continued) with dry gas blanket, normal adnosphere pressure fluctuations may cause minor in and out flow l

through any existing system leaks. Analyses have demonstrated that this " breathing" of the cell l

or even the exposure to atmospheric air (diffusion) when the system is opened to allow for i

necessary maintenance will not significantly affect deposit moderation. Even for periods much

[

longer than the one year limitation, moderation above an H/U ratio of 4 would not be experienced.

l The daily surveillance demonstrates that the gas blanket is maintained as assumed in the analyses.

l The LCO requirements of this TSR assure nuclear criticality safety for equipment with UQF2 l

deposits greater than a safe mass.

l l

Maintenance evolutions or cascade system maintenance terminology, used in the Required Action I

statements, include other related tasks such as decontamination and sampling. Condition C is l

considered to be met when the UF primary system is first breached. Also the potential for l

moderation from RCW system water is controlled by NCSA requirements and demonstrated to l

meet the double contingency principle.

l l

l 2.2 30a

T'SR-PORTS PROPOSED September 28,1999 RAC97XO422 SECTION 2.7 SPECIFIC TSRs FOR X-326 CASCADE FACILITY 2.7.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.7.3.14 Moderation Control Applicability: Cascade Operational Modes I, II, III, IV, V, VI LCO: Moderation Control shall be maintained when the UO F mass is > safe mass.

2 2 ACTIONS:

Note: TSR 1.6.2.2(d) does not apply Condition Required Actions Completion Time A.

UO F deposit > safe mass in a A.1 Conunue to maintain a fluorinatmg Immediately 3 3 fluorinating (including chemical environment for the deposit treatment) environment.

ASV A.2 Initiate accons to determine the cause of Immediately deposit.

AND A.3 Establish and document a plan of action 30 days AhD 3

A.4 Iniriate SR 2.7.3.14.3 90 Days B.

UO F deposit > safe mass with the B.I.I Establish a dry cover gas blanket at a 14 Within 72 Hours after 3 3 deposit not in a fluorinating psia except when performing maintenance entering Mode VI environment.

or operational activities associated with remediation of the deposit equipment removal or leak repairs.

AhD B. I.2 Initiate SR 2.7.3.14.2 12 Hours AND B.2 Remove equipment containing the UQF 366 days 2

deposit from the cascade OR Note:

Upon compleuon B.3, Condition A is re-entered.

B.3 Imtiate re-fluonnation activities Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of removal of dry cover gas blanket C.

Installed equipment containin; known C.1 Apply TSR 2.7.3.13 as appropriate to Imniediately or previously unknown deposit of equipment removed UO F, deposit > safe mass opened to ASV 2

atmosphere.

C.2 Cover openmg(s) that expose UQF Immediately after 3

deposit to atmosphere when maintenance determining acceptable evoluuons are as impacting equipment.

UF./HF condiuons AND C.3 Maintam dry cover gas blanket = 14 psia Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after when cascade system mamtenance completing REQUIRED evolutions are 33 mpacting equipment.

ACTION C.2 i

AND Note:

Upon complenon C.4, Cordition B is re-ent red.

C.4 Maintain dry cover gas blanket a 14 psia Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after following compicoon of cascade system completing system maintenance on affected equipment and maintenance UO,F, deposit is not in a fluorinanng environment.

2.7-23

r

'fSR-PORTS PROPOSED September 28,1999 l

RAC97X0422 SECTION 2.7 SPECIFIC TSRs FOR X-326 CASCADE FACILITY l

2.7.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.7.3.14 Moderation Control (continued)

Condition Required Actions Completion Time D.

Uof deposit > safe mass, not in a D.l.1 Increase coolant system pressure to >

4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> fluorinatmg environment and coolant RCW condenser pressure.

system pressure s RCW condenser AND pressure.

D.1.2 Imtiate sR 2.7.3.14.1 12 Hours OR D.2 Dra% RCW from coolant condenser 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> l

E.

Uof deposit > safe mass with the E.1 Re-establish a dry cover gas blanket = 14 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> deposit not in a fluorinating

psia, environment and required dry cover gas blanket < 14 psia.

SURVEILLANCE REQUIREMENTS:

Frequency Surveillance Each shift when not in a fluorinating SR 2.7.3.14.1 Verify coolant system l

environment, deposit > safe mass and pressure > RCW condenser pressure.

l RCW not drained.

Each shift when dry cover gas blanket is SR 2.7.3.14.2 Monitor the system pressure l

required by Condition B or C and adjust pressure to a 14 psia.

l Quarterly when in Condition A SR 2.7.3.14.3 Monitor size of the deposit.

l Quarterly SR 2.7.3.14.4 Perform routine qualitative radiation surveys of bypass housings to check for deposits and initiate "NDA" j

quantitative measurements based on

" radiation reading trending".

1 2.7-24

\\

TSR-PORTS PROPOSED September 28,1999 RAC97X0422

~ SECTION 2.7 SPECIFIC TSRs FOR X-326 CASCADE FACILITY 2.7.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.7.3.14 Moderation Control (continued)

BASIS:

As used in this TSR, the term " safe mass" is defined as being 43.5% of the minimum fissionable

[

mass for system conditions (enrichment, geometry, H/U, reflection, etc.). Cascade deposits of l UO F (and deposits of other compounds resulting from wet air inleakage) and freeze-out of UF.

l 22 are an expected result of normal operation. It is considered non-credible for a dry criticality to l

occur in the Cascade. Therefore, for a freeze-out condition, criticality would not result and the l

UF freeze-out may be remediated at the discretion of the operating organization. Any deposit that l

6 has a uranium mass less than the "always" safe mass (i.e. optimally moderated material) may be l

remediated at the discretion of the operating organization. In regard to those situations in which

[

a loss of moderation control could result in criticality, it has been determined that NCSA specified l

controls provide double contingency against the inleakage ofliquid water into the cascade. Based

[

on additional technical evaluations it is not possible to hydrate a deposit of uranyl fluoride above l

a H/U ratio of 4 by exposure to ambient air within the process buildings. Therefore, there is no l

potential for criticality when a cascade deposit is less than the safe mass at a H/U ratio of 4 due l

to exposure to atmospheric water vapor in the ambient process building air.

l l

UF, F, and CIF react with available water more readily than UO:F absorbs water. For l

6 2

3 2

instance, water entering onstream cascade equipment will preferentially react with UF to form l

6 more UO F rather than react with UO F to form hydrates (moderated forms) of UQF. HF gas l

2 2 2 2

formed as a byproduct of the water-UF reaction cannot liquefy to moderate a deposit at the l

6 pressures encountered in the cascade. A UQF deposit cannot become moderated if it is being l

2 continuously fluorinated and moderation is not a concern until the equipment is taken off-stream l

and evacuated of UF. Continued fluorination of the deposit provides nuclear criticality safety l

6 by preventing moderation of the deposit.

l l

Chemical treatment processes which involve the addition of ClF and/or F (i.e. fluorinating l

3 2

agents) provide the same level of moderation control as when the deposit is exposed to UF,.

I Fluorinating gas treatments have been used as a means of drying out equipment after exposure to l

atmospheric air and for removing / reducing uranium deposits since the enrichment plants were l

placed into service. It has been demonstrated that these fluorinating agents will react vigorously l

and preferentially with any available moisture. The presence of excess fluorinating agents will l

- not only prevent further hydration of a deposit but will over time effectively remove any free l

moisture and dehydrate the exposed deposit to an H/U ratio as low as when the deposit was l

exposed to the UF process. In addition, use of fluorinating agents will convert UO:F deposits l

6 2

toUF, thereby reducing the deposit mass. Repeated use of the fluorinating agents (i.e. chemical l

6 treatment) will proceed to reduce / eliminate the deposit which is the safest condition. Therefore, l

a deposit that has been hydrated to some extent due to " breathing" or during the times necessary l

to expose the deposit to atmosphere when maintenance functions are performed can be dehydrated l

2.7-25

' TSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.7 SPECIFIC TSRs FOR X-326 CASCADE FACILITY 2.7.3 LIMITING CONTROL SE'ITINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.7.3.14 Moderation Control (continued) by the presence of a fluorinating agent. The sustained liberation of UF from the deposit during l

6 a chemical treatment is the proven indicator that the deposit has been dehydrated. Once a deposit j

has been dehydrated, re-entry into Condition B establishes a new initiating time for required l

actions. After having been exposed to a fluorinating environment in which there has been the l

sustained liberation of UF, the re-entry to the buffered condition for one year will not decrease j

6 the assumed safety margin for this condition. Chemical treatment activities as discussed in this l

LCO may include preparation activities such as evacuation, leakrate, seal checks and cell startup.

l l

UO F deposits in onstream operating equipment are not a nuclear criticality safety concern due l

22 to continuous fluorination of the deposit. Over time, sustained or large wet air inleakage in l

operating equipment (active process area) will readily announce itself in the form of changing l

motor loads, compressor surging, line recorder readings, stage control valve positions, A-suction l

pressures, etc.. Additionally, deposit formation in operating equipment will be dispersed by the l

gas flow. This dispersion of UO F can occur on the inside of process piping, across barrier l

2 tubing, on cooler fins and inside compressors on the rotor and stator. Due to this dispersion, the l

formation of deposits in unsafe geometries in active process areas where there is UF gas flow is l

not likely, given the above indicators._ However, the above mentioned indicators and continuous l

gas flow are not always available for wet air inleakage in bypass / auxiliary piping, expansionjoints l

and valves (inactive process areas). Operational experience indicates that quarterly surveillances l

by NDA methods for UO F deposits in inactive process areas is appropriate for early detection l

2 2 and pmdent remediation of the deposit. Follow up surveys are conducted to assure that the deposit l

does not become sufficiently large to become an operational problem or a cascade structural j

concern.

l l

Routine NDA surveillance methods are oflimited value, with respect to quantification of deposit I

size, for active process areas which include compressors, converters, process gas coolers and l

j freezer /sublimers. However, sustained or large wet air inleakage in active process areas will l

readily announce itself which will prompt corrective actions by operating personnel. Also, the l

forn;ation of UO F deposits in unsafe geometries in active process areas is not likely given the l

2 2 above corrective actions. The limited ability to hydrate a deposit in in-place process equipment l

l assures that these deposits will remiin critically safe after shutdown. Thus the primary concern l

l for the formation of UO F deposits in unsafe geometries in operating equipment is if this l

2 2 equipment trips or is shutdown while containing UF and massive wet air inleakage occurs. In this l

6 event, the wet air inleakage will be obvious from the equipment leak rate which will prompt l

corrective actions to limit the size of the deposit.-

l l

For shutdown equipment, moderation control can be provided by a fluorinating environment or l

by_.a dry cover gas (plant air or nitrogen) blanket over the deposit even if significant wet air l

inleakage has occurred. Once a system has been isolated from the cascade and filled to 214 psia l

2.7-25a

I l

TSR-PORTS -

PROPOSED September 28,1999 RAC97X0422 1

1 SECTION 2.7 SPECIFIC TSRs FOR X-326 CASCADE FACILITY 2.7.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES l

2.7.3.14 Moderation Control (continued) with dry gas blanket, normal atmosphere pressure fluctuations may cause minor in and out flow l

through any existing system leaks. Analyses have demonstrated that this " breathing" of the cell l

or even the exposure to atmospheric air (diffusion) when the system is opened to allow for l

necessary maintenance will not significantly affect deposit moderation. Even for periods much

[

longer than the one year limitation, moderation above an H/U ratio of 4 would not be experienced.

l The daily surveillance demonstrates that the gas blanket is maintained as assumed in the analyses.

l The LCO requirements of this TSR assure nuclear criticality safety for equipment with UOF l

2 deposits greater than a safe mass.

l l

Maintenance evolutions or cascade system maintenance terminology, used in the Required Action l

statements, include other related tasks such as decontamination and sampling. Condition C is l

considered to be met when the UF Primary system is first breached. Also the potential for l

6 moderation from RCW system water is controlled by NCSA requirements and demonstrated to l

meet the double contingency principle.

l 2.7-25b l

E 1

i l,

TSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.2 SPECIFIC TSRs FOR X-330 AND X-333 FACILITIES 2.2.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES l

2.2.3.15 Moderation Control L

)

l Applicability: Cascade Operational Modes I, II, III, IV, V, VI t

j LCO: Moderation Control shall be maintained when the UO F mass is > safe mass.

22 ACTIONS:

Note: TSR 1.6.2.2(d) does not apply Condition Required Actions Completion Time A.

UO F deposit > safe mass in a A.1 Continue to maintain a fluorinating Immediately 2 3 fluorinating (including chemical environment for the deposit traann==r) environment.

AND A.2 Ininate actions to determine the cause of Immediately deposit..J....'.......

AND A.3 Establish and document a plan of action 30 days AND A.4 Initiate SR2.2.3.15.3 90 Days B.

UO,F. deposit > safe mass with the B.I.1 Establish a dry cover gas blanket at Withirre 72 Hours after deposit not in a fluorinating

u..

d., '_..: "sner to = 14 entermg Mode VI and environmen; m

.'.J. " :..J J... 4 psia except when performing maintenance a _-.. : :. ' T.

... - - - = r -o....

or operational activities associated wh regenre remediation of the deposit. equipment removal or leak repair.

AND BJ.2 Initiate SR 2.2.3.15.2 12 Hours AND B.2 Remove equipment containing the UO:Fa fee 366 days deposit ? :,... from the cascade OR Nosei Upon compleuen of B.3, Condition A is re-ensered.

B.3 Initiate re-fluormanon activities Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of rernovel of dry cover ans blanket C2 InsuiDod arpie==nt cone==ny known C.1 Apply TSR 2.2.3.16 as appropriate to immediately

~

or previously unknown deposit of,

AND equipment removed UO,F, deposit > safe manas opened to

~

Im:nediately after atmosphere.

C.2 Cover opening (s) that expose UO.F, deposit to atmosphere when maintenance determining acceptable evolutions are as impacting equipment.

UF./HF wnditions C.'J Mainiain dry Eover gas blanket a 14 psia Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after when cascade system =haarre completing REQUIRED evolutions are as impacting equipment.

ACTION C.2 AND Note:

Upon compienon C.4, Condition B is re-ensered.

C.4 Maintain dry cover gas blanket = 14 psia Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after following completN of cascade system completing system maintenance on anected equipment and maintenance 4

I UO,F, deposit is not in a fluorinating environment.

i 2.2-27

I TSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.2 SPECIFIC TSRs FOR X-330 AND X-333 FACILITIES 2.2.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.2.3.15 Moderation Control (continued)

~

Condition Required Actions Completion Time D.

Uof, deposit > safe mass. not in a D.1.1 Ir. crease coolant system pressure to >

4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> j

fluonnaring environmem.,,.-..

RCW condenser pressure.

.m.

.. -....a and coolant system AND pressure s RCW condenser pressure.

D.I.2 Initiate sR 2.2.3.15.1 12 Hours OR I

D.2 Drain RCW from coolant condenser 20 +6 hours E.

Uo,F, deposit > safe mass with the E.1 Re-establish a dry cover gas blanket a 14 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> deposit not in a fluorinating psia.

ca irow.ent and required dry cover gas blanket < 14 psia.

SURVEILLANCE REQUIREMENTS:

Frequency Surveillance Each shift when not in a fluorinating SR 2.2.3.15.1 Verify coolant system environment, deposit > safe mass and pressure > RCW condenser pressure.

RCW not drained Each shift when in dry cover gas blanket is SR 2.2.3.15.2 Monitor the system pressure required by Condition B or C and adjust pressure to a 14 psia.

Quarterly when in Condition A SR 2.2.3.15.3 Monitor UO F, dcyosit >

5efc nm55 foi size of the deposit when in e asava ana6uag wasy aa vuauwut.

Quarterly SR 2.2.3.15.4 Perform routine qualitative radiation surveys of bypass housings to check for deposits and initiate "NDA" quantitative measurements based on

" radiation reading trending".

QOM 2.2-28 l

TSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.2 SPECIFIC TSRs FOR X-330 AND X-333 FACILITIES 2.2.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.2.3.15 Moderation Control (continued)

BASIS:

As used in this TSR, the tenn " safe mass" is defined as being 43.5 % of the minimum fissionable mass for system conditions (enrichment, geometry, H/U, reflection, etc.). Cascade deposits of UO F (and deposits of other compounds resulting from wet air inleakage) and freeze-out of UF.

22 are an expected result of normal operation. It is considered non-credible for a dry criticality to occur in the Cascade. Therefore, for a freeze-out condition, criticality would not result and the UF freeze-out may be remediated at'the discretion of the operating orgamzadon. Any deposit that 6

has a uranium mass less than the "always" safe mass (i.e. cptimally moderated material) and may be remediated at the discretion of the operating organization. In regard to those situations in which a loss of moderation control could result in criticality, it has been determined that NCSA specified controls provide double contingency against the inleakage of liquid water into the cascade. Based on additional tecimical evaluations it is not possible to hydrate a deposit of tranyl fluoride above a H/U ratio of 4 by exposure to ambient air'within the process buildings.

Therefore, there is no potential for critica'ity when a cascade deposit is less than the safe mass at a H/U ratio of 4 due to exposure to atmospheric water vapor in the ambient process building air.

UF, Fg and CIF react.with available water more readily than UQF absorbs water. For 3

2 instance, water entering onstream cascade equipment will preferentially react with UF to form more UO F rather than react with UQF to form hydrates (moderated forms) of UQF HF gas 22 2

2 formed as a byproduct of the water-UF reaction cannot liquefy to moderate a deposit at the 6

pressures encountered in the cascade. _ A UQF deposit cannot become moderated if it is being 2

continuously fluorinated and moderation is not a concern until the equipment is taken off-stream had evacuated of UF. Continued fluorination of the deposit provides nuclear criticality safety by 6

preventing moderation of the deposit.

Chemical treatment processes which involve the addition of CIF and/or F (i.e. fluorinating 3

2 agents) provide the same level of moderation control as when the deposit is exposed to UF.

Fluorinating gas treatments have been used as a means of drying out equipment after exposure to atmospheric air and for removing / reducing uranium deposits since the enrichment plants were placed into service. It has been demomtrated that these fluorinating agents will react vigorously and preferentially with any available moisture. The presence of excess fluorinating agents will not only prevent further hydration of a deposit but will over time effectively remove any free moisture and dehydrate' the exposed' deposit to an H/U ratio as low as when the deposit was

. exposed to the UF process. In addition, use of fluorinating agents will convert UQF deposits 6

2 to.UF, thereby reducing the deposit mass. Repeated use of the fluorinatirg agents (i.e. chemical treatment) will proceed to reduce / eliminate the deposit which is the safest condition. Therefore, a deposit that has been hydrated to some extent due to " breathing" or during the times necessary to expose the deposit to atmosphere when maintenance functions are performed can be dehydrated 2.2-29

l TSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.2 SPECIFIC TSRs FOR X-330 AND X-333 FACILITIES 2.2.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.2.3.15 Moderation Control (continued) by the presence of a fluorinating ag$nt. The sustained liberation of UF. from the deposit during a chemical treatment is the proven indicator that the deposit has been dehydrated. Once a deposit has been dehydrated, re-entry into Condition B establishes a new initiating time for required actions. After having been exposed to a fluorinating environment in which there has been the sustained liberation of UF., the re-entry to the buffered condition for one year will not decrease the assumed safety margin for this condition. Chemical treatment activities as discussed in this LCO may include preparation activities such as evacuation, leakrate, seal checks and cell startup.

UO F deposits in onstream operating equipment are not a nuclear criticality safety concern due

)

2 2 to continuous fluorination of the deposit. Over time, sustained or large wet air inleakage in l

operating equipment (active process area) will readily announce itself in the form of changing motor loads, compressor surging, line recorder readings, stage control valve positions, A-suction pressures, etc.. Additionally, deposit formation in operating equipment will be dispersed by the gas flow. This dispersion of UO F can occur on tP ' mide of process piping, across barrier 2 2 tubing, on cooler fins and inside compressors on the, u w! stator. Due to this dispersion, the formation of deposits in unsafe geometries in active process areas where there is UF, gas flow is

~

not likely, given the above indicators. However, the above menticned indicators and continuous gas flow are not always available for wet air inleakage in bypass / auxiliary piping, expansion joints and valves (inactive process areas). Operational experience indicates that quarterly surveillances by NDA methods for UO F deposits in inactive process areas is appropriate for early detection 2 2

~

and prudent remediation of the deposit. Follow up surveys are conducted to assure that the deposit does not become sufficiently large to become an operational problem or a cascade stmetural I

concern.

Routine NDA' surveillance methods are oflimited value, with respect to quantification of deposit size, for active process areas which include compressors, converters, process gas coolers and freezer /sublimers. However, sustained or large wet a r inleakage in active process areas will i

readily announce itself which will prompt corrective actions by operating personnel. Also, the formation of UO F deposits in unsafe geometries in active process areas is not likely given the 2 2 above corrective actions. The limited ability to hydrate a deposit in in-place process equipment assures that these deposits will remain critically safe after shutdown. Thus the primary concern for the formation of UO F deposits in unsafe geometries in operating equipment is 11 this 2 2 equipment trips or is shutdown while centaining UF and massive wet sir inleakage occurs. In this 6

event, the wet air inleakage will be obvious from the equipment leak rate which will prompt corrective actions to limit the size of the deposit.

For shutdown equipment, moderation control can be provided by a fluorinating environment or by a dry cover gas (plant air or nitrogen) blanket over the deposit even if significant wet air inleakage has occurred. Once a system has been isolated from the cascade and filled to a 14 psia 2.2-30

TSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.2 SPECIFIC TSRs FOR X-330 AND X-333 FACILITIES 2.2.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.2.3.15 Moderation Control (continued) 6ith'drj gai blanket,' normal itni'ospiireiressure' fluciusioiis isaY cause~ minor in and'otit flow

~

~

thr6 ugh any existing' system leaks $ Analyses have' demonstrated 'that this " breathing" of tiie cell of even the exp6sure "to atmo' pheric' air (diffusion) whsi the system is' opened to' allowlfor s

neceisary ' aintenance will not significantly' affect deposit nioderation. Even for periods'much m

longer"than the one year limitation, morteration'above'an H/U ratio of 4 would not be experienced.

The; daily" surveillance demonstrates that tir. gas blanket is maintained as assumed in the analyses.

1The LCO requirements'of this TSR assure nuclear criticality safety for equipment with UC F 22 deposits greater than'a safe mass.

Mainiinance evolutions or cascade'syitem maintenance terminology, used in the Required Action statements' include other related tasks such as decontamination and sampling. Condition C is considered to be met 'when the UF primary system is first breached. Also the potential for 6

moderation from RCW system water is' controlled by NCSA requirements and demonstrated to meet the double contingency principle.

i i

Oem l

2.2-30a

I l

TSR-PORTS PROPOSED Septemi, r 28,1999 RAC97X0422 SECTION 2.7 SPECIFIC TSRs FOR X-326 CASCADE FACILITY 2.7.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES l

2.7.3.14 Moderation Control t

Applicability: Cascade Operational 5 ades I, II, III, IV, V, VI LCO: Moderation Control shall be maintained When the UO F mass is > safe mass.

2 2 l

ACTIONS:

Note: TSR 1.6.2.2(d) does not apply Condition Required Actions Completion Time A.

UO,F, deposa > safe mass in a A.1 Continue to maintain a nuorinatmg Immediately nuorinating (including chemical environment for abe deposit trestraent) environment.

AND A.2 Initiate actions to deternune the cause of immediately deposit..J.m.. T...

AND A.3 Establish and docunwns a plain of action 30 days AND A.4 Initiate sR 2.7.3.14.3 90 Davs B.

UO,F, deposit > safe mass with the B.I.!

Establish a dry cover gas blanket at Wittun4 72 Hours after deposit not in a nuorinating

" n....

.2 ;L

".hnem 14 entering Mode Viand j

environmei.e LJ, '

..J J-..

J psia except when performing maintenance

: UF.

i L......m..,

..,. r % > ~

or operational activities associated with negatrve remediation of the deposit, equipment l

removal or icak repairs.

AND B.I.2 Initiate SR 2.7.3.14.2 12 Hours AND B.2 Remove equipment contaming the UO:F tee 366 days deposit ? >.L.. ~ from the cascade OR Note:

Upon completion B.3. Coralition A is re-entered.

B.3 Ininate re. fluorination activities Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of removal of dry cover gas blanket C.

Installed ~pe-ne containing known C.1 Apply TSR 2.7.3.15 as appmpriate to Immediately or prev:ously unknown deposit of equipment removed UO,F, deposit > safe mass opened to AND atmosphere.

C.2 Cover opening (s) that expose UOS, Immediately after j

deposit to atmosphere when mamtenance determining acceptable evolutions are 33 impacting equipment.

UP./liF condinons AND C.3 Maintain dry cover gas blanket a 14 psia Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after when cascade system maintenance completing REQUIRED evolutions are ma impacting equipmert ACTION C.2 AND Note:

Upon c.ompletion C.4. Condition B is re-entered.

l C.4 Maintain dry cover gas blanket i 14 psia Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after following completion of cascade system completing system maintenance on affected equipment and maintenance UOS, deposit is not in a nuorinating environment.

l 2.7-23

' TSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.7 SPECIFIC TSRs FOR X-326 CASCADE FACILITY 2.7.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.7.3.14 Moderation Control (continued) s Condition Required Actions Completion Thee D.

Uo,F, deposit > safe trase. mt in a D.I.1 Increase coolant system pressure to >

4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> fluorinating environmen;.,,.... m.

RCW condenser pressure.

shutdomrmode and coolant syssem AND pressure s RCW condenser pressure.

D.1.2 Initiane sR 2.7.3.14.1 12 Hours OR D.2 Drain RCW from coolant condenser 20 % hours E'

UO.F. deposit > safe mass with the E.1 Re-establish a dry cover gas blanket a 14 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />

^

l I

deposit not in a fluorinating.

psia.

environment and required dry cover gas blanket < 14 pair.

1' SURVEILLANCE REQUIREMENTS:

Frequency Surveillance i

Each shift when no't in a' fluorinating SR 2.7.3.14.1 Verify coolant system environment,' deposit > safe mass and pressure > RCW condenser pressure.

RCW not drained.

Each shift when in dry cover gasLblanket is SR 2.7.3.14.2 Monitor the system pressure required by Condition B or C and adjust pressure to 214 psia.

Quarterly when in' Condition'A SR 2.7.3.14.3 Monitor UO F, depuss >

- ' - - - - '-- size of the deposit e!,cn in e f;sm o..s en uu,e m a.

Quarterly SR 2.7.3.14.4 Perform routine qualitative radiation surveys of bypass housings to check for deposits and initiate "NDA" quantitative measurements based on

" radiation reading trending" 2.7-24

L TSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.7 SPECIFIC TSRs FOR X-326 CASCADE FACILITY l

-2.7.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR

(

OPERATION, SURVEILLANCES L

L 2.7.3.14 Moderation Control (continued)

BASIS:

As'used in this TSR, theierm " safe mass" is defined as being 43.5% of the minimum fissionable mass for system conditions (enrichment, geometry, H/U, reflection, etc.). Cascade deposits of UO,F (and deposits of other compounds resulting from wet air inleakage) and freeze-out of UF 2

6 are an expected result of normal operation. It is considered non-credible for a dry criticality'to occur in the Cascade. Therefore, for a freeze-out condition, criticality would not result and the UF freeze-out may be remediated at the discretion of the operating organization. - Any deposit that 6

has a uranium mass less than the "always" safe mass (i.e. optimally moderated material) may be remediated at the discretion of the operating organization. -In regard to those situations in which a loss of moderation control could result in criticality, it has been determined that NCSA specified controls provide double contingency against the inleakage of liquid water into the cascade. Based on additional technical evaluations it is not possible to hydrate a deposit of uranyl fluode above

~

a H/U ratio of_4.by exposure to' ambient air within the process buildings. Therefore,' there is no potential for criticality when a cascade deposit is less than the safe mass at a H/U ratio of 4 due to exposure to atmospheric water vapor in the ambient process building air.

UF., F. and CIF react with available water more readily than UQF absorbs water. For 2

3 2

instance, water entering onstream cascade equipment will preferentially react with UF to form i

more UO F rather than react with UQF to form hydrates (moderated forms) of UQF. HF gas 22 2

2 formed as a byproduct of the water-UF reaction cannot liquefy to moderate a deposit at the pressures encountered in the casse. A UQF deposit cannot become moderated if it is being 2

continuously fluorinated and moderation is not a concern until the equipment is taken off-stream and evacuated of UF., Continued fluorination of the deposit provides nuclear criticality safety 6

by preventing moderation of the deposit.

Chemical treatment processes which involte' the addition of CIF axl/or F (i.e. fluorinating 3

2 agents) provide the same level of moderation control as when the deposit is exposed to UF.

Fluorinating gas treatments liave been used ts a means of drying out equipment after exposure to atmospheric air arid for removins/ reducing uranium deposits since the enrichment plants were placed into service. -It has been' demonstrated that these fluorinating agents will react vigorously and preferentially with any available' moisture. The presence of excess fluorinating agems will not only prevent further hydration of a deposit but will over time effectively remove any free moisture and dehydrate the exposed deposit to an H/U ratio as low as when the deposit was exposed to the UF6 Process. In addition, use of fluorinating agents will convert UQF deposits 3

l.

toUF.; thereby reducing the deposit mass. Repeated use of the fluorinating agents (i.e. chemical treatment) will proceed to reduce / eliminate the deposit which is the safest condition. Therefore, i

a deposit that has been hydrated to some extent due to " breathing" or during the times necessary to expose the deposit to atmosphere when maintenance functions are performed can be dehydrated 2.7-25

r i

TSR-PORTS PROPOSED September 28,1999 c

L RAC97X0422 H

f SECTION 2.7 SPECIFIC TSRs FOR X-326 CASCADE FACILITY 2.7.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.7.3.14 Moderation Control (continued) b tlie presence of a fluorinating agent. The sustained liberation of UF from the deposit during 6

a chemical treatment is the proven indicator that the' deposit has been' dehydrated. Once a deposit i

has' bedn dehydrated, re-entry into Condition B establishes a new initiating time for required l

actions. After having been exposed to a fluorinating environment in which there has been the sustained liberation of UF, the re-entry to the buffered ~ condition for one year will not decrease 6

the assumed safety margin for this condition.1 Chemical treatment activities as discussed in this l

. LCC' may include preparation activities such as evacuation, leakrate, seal checks and cell startup.

l UO F de' posits in onstream operating equipment are not a nuclear criticality safety concern due 2 2 to' continuous fluorination of the deposit..Over time, sustained or large wet air inleakage in operating equipment (active process area) will readily announce itself in the form of changing motor loads, compressor surging, line recorder readings, stage control valve positions, A-suction pressures, etc.. Additionally, deposit formation in operating equipment will be dispersed by the gas flow.. This dispersion of_UQF can occur on the inside of process piping, across barrier 2

tubing, on cooler fins and inside compressors on the rotor and stator. Due to this dispersion, the formation of deposits in unsafe geometries in active process areas where there is UF gas flow is not likely, given the above indicators. However, the above mentioned indicators and continuous gas flow are not always available for wet air inleakage in bypass / auxiliary piping, expansbn joints and valves (inactive process areas). Operational experience indicates that quarterly surveillances by NDimethods for UQF deposits in inactive process areas is appropriate fer early detection l

2 and pmdent remediation of the deposit. Follow up surveys are conducted to assure that the ' eposit d

does not become sufficiently large to become an operational problem or a cascade structural concern.

1 Routine NDA surveillance methods are of limited value, with respect to quantification of deposit size, for active process areas which include compressors, converters, process gas coolers and freezer /sublimers. However, sustained or large' wet' air inleakage in active process areas will readily announce itself which will prompt corrective actions by operating personnel. Also, the formation of UO F deposits in unsafe geometries in active' process areas is not likely given the 2 2 above corrective actions. - The limited ability to hydrat'e a deposit in in-place process ' equipment assures that these deposits will remain critically safe after shutdown. - Thus the primary concern 4

for the formation of UO F deposits in unsafe geometries in operating equipment is if this 2 2 equipment trips or is shutdown while containing UF and massive wet air inleakage occurs. In this 6

event, the wet air inleakage will be obvious from the equipment leak rate which will prompt corrective actions to limit the size of the deposit.

}

For shutdown equipment, moderation control can be provided by a fluorinating environment or l

by a dry cover gas (plant air or nitrogen) blanket over the deposit even if significant wet air inleakage has occurred. Once a system has been isolated from the ccscade and filled to : 14 psia 2.7-25a I.

F TSR-PORTS PROPOSED September 28,1999 RAC97X0422 SECTION 2.7 SPECIFIC TSRs FOR X-326 CASCADE FACILITY 2.7.3 LIMITING CONTROL SETTINGS, LIMITING CONDITIONS FOR OPERATION, SURVEILLANCES 2.7.3.14 Moderation Control (continued)

)

With'dri gasblAnkei,"n6rmal atmbiphere pressurefflu6tuatiohs n6) cause ininor in and ouiflow thrbugh any existing sistein leaks.1 Analyses have~ demonstrated thaithis " breathing". of the" cell 6Feven thelexposure to atmospheric air (diffusion).whenlthe system isJopened to allow 1for

~

~

necessary maintenance will not significantly affect deposit moderation. Even for periods msch lunger ~than the one year limitation, moderation abo' e an H/U ratio of 4 would not be experienced.

v The daily surveillance demonstrates that the gas blanket is maintaineA as assumed in the analyses.

iThe LCO requirements of this TSR ' ssure nuclear criticality safety' for equipment 'with UC F a

2 2 deposits greater than a safe mass.

Maintenance evolutions ' r cascade system maintenance terminology, used in the Required Action o

~

statements, include other related tasks'such as decontamination and sampling. Condition C is considered to be met when the UF primary system is first breached. Also'the potential for 6

moderatio~n from RCW system water is controlled by NCSA requirements and demonstrated to meet the double contingency principle.

)

2.7-25h