ML20141G201

Application for Rev to Certificate of Compliance 7002, Revising Tsr Section 2.5.4.4,Scale Pit Raschig Rings,To Reflect That Erp Scale Pit Positions 1A & 2 Require Only Six Inches of Raschig Rings Instead of Twelve Inches

ML20141G201
Person / Time
Site:	Portsmouth Gaseous Diffusion Plant
Issue date:	05/16/1997
From:	Millerl J UNITED STATES ENRICHMENT CORP. (USEC)
To:	Paperiello C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
GDP-97-0075, GDP-97-75, NUDOCS 9705220205
Download: ML20141G201 (14)

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Enrichmint Corporition 2 Democracy Center 6903 Rockledge Drive Bethesda. MD 20817 Tel: (301)564-3200 Fax: (301) 564-3201 Utiitetl States Enrichinesit Coriw>ratiori JAMES H. MILLER Dir. (301) 564-3309 VICE PRESIDENT, PRODUCTION Fax: (301) 571-8279 May 16,1997 Dr. Carl J. Paperiello SERIAL: GDP 97-0075 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-Scale Pit Raschig Rings

Dear Dr. Paperiello:

i In accordance with 10 CFR 76.45, the United States Enrichment Corporation (USEC or Corporation) hereby submits a request for amendment to the certificate of compliance for the Portsmouth, Ohio Gaseous Diffusion Plant (GDP). This certificate amendment request revises TSR Section 2.5.4.4, Scale Pit Raschig Rings, to reflect that the ERP scale pit positions l A and 2 require only 6 inches of Raschig l

rings instead of the 12 inches as previously stated to enhance nuclear criticality safety. Once revised, the l

Design Feature would read as follows: "ERP, LAW and Tails scale pits shall contain Borosilicate glass Raschig rings to a minimum depth of 6 inches".

l UFs ylinders are filled directly above the scale pits at the withdrawal stations. Quantities of uranium c

could accumulate in the scale pit if a release were to occur. Should this accumulated mass of uranium beccme fally moderated a criticality could occur. The Raschig ings are used in the scale pits to increase 1

the mass of uranitun and moderator required to accumulate in the scale pits for a criticality to occur. Six inches of Raschig rings is adequate to assure that accumulation of enough uranium and moderator (water) in the pit for a criticality to occur is not credible based on the contingency controls identified.

g)M-i 9705220205 970516 l l ll l t

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{DR ADOCK 0700 2

Offices in Paducah, Kentucky Port, mouth. Ohio Washington, DC

l-L Dr. Carl J. Paperiello May 16,1997 H

GDP 97-0075 Page 2

- to this letter provides a detailed description and justification for the proposed change to the ERP positions l A and 2 scale pit Raschig ring levels. Enclosure 2 is a copy of the revised TSR and SAR pages. The TSR page is provided for your review and approval. The revised S AR pages have been

. evaluated in accordance with 10 CFR 76.68. Based on the results of the 10 CFR 76.68 evaluation, the

enclosed SAR pages do not require prior NRC review and approval and are provided for information only. These revised SAR pages reflect revisions associated with this certificate amendment request and may not reflect other approved changes ta these SAR pages. Enclosure 3 contains the basis for USEC's determination that the proposed change associated with this certificate amendment request is not significant.-

This proposed certificate amendment request is required to change the Raschig ring depth in the ERP withdrawal position l A'and to allow for the operation of the ERP withdrawal position 2. For ERP position 2, the current 12 inch depth of Raschig rings interferes with proper scale operation due to the j

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= limited space available within'the scale pit. For ERP position I A, the change in Raschig ring depth is requested so that the depth of Raschig rings at this ERP position is consistent with the depth of Raschig rings specified for other withdrawal positions.

Since this approved change will allow the ERP withdrawal position 2 to be retumed to service, thereby enhancing the ability to withdrawal product,

- USEC requests this certificate amendment request receive top priority of all Portsmouth certificate amendment requests submitted to date and that NRC review and approval occur as soon as possible. The amendment should become effective no later than 30 days from issuance.

Any questions related to this subject should be directed to Mr. Mark Smith at (301) 564-3244.

Sincerely, i

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es H. Miller Vice President, Production b

Enclosures:

As Stated L

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NRC Region III Office l

- NRC Resident Inspector - PGDP

- NRC Resident Inspector - PORTS f

DOE Regulatory Oversight Manager L

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OATH AND AFFIRMATION 1

I, James H. Miller, 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 l

. Regulatory Commission this Certificate ' Amendment Request for the Portsmouth Gaseous Diffusion Plant, that I am familiar with the contents thereof, and that the statements made and matters set forth 1

therein are true and correct to the best of my knowledge, information, and belief i

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James H. Miller Subscribed to before me on this I day of k,7tv/

,1997.

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GDP97-0075 Page 1 of 2 United States Enrichment Corporation (USEC)

Proposed Certificate Amendment Request Scale Pit Raschig Rings Detailed Description of Change Specific TSR and SAR Sections Affected The proposed change would revise TSR 2.5.4.4, Scale Pit Raschig Rings from " Scale pits shall contain Borosilicate glass Raschig rings to a nominal depth of 12 inches at ERP(positions l A and 2),6 inches at ERP(position IB) and 6 inches at LAW / FAILS" to "ERP, LAW and Tails scale pits shall contain Borosilicate glass Raschig rings to a minimum depth of 6 inches.". S AR Sections 3.2.2.4.7 and

= 4.2.2.2 will also be revised to reflect that only 6 inches of Borosilicate glass Raschig rings are required in all of the ERP, LAW and Tails scale pits.

Reason for Change At the ERP Station, the filling of the number 2 scale pit with 12 inches of Raschig rings interferes with the proper operation of the scale due to the limited space available in the scale pit. In addition, the number l A ERP scale pit will only be filled with 6 inches of Raschig rings to avoid inconsistencies with the other withdrawal scale pits.

Justification of the Change The Nuclear Criticality Safety Approval (NCSA) document for the Extended-Range Product (ERP)

Withdrawal Station has established that the operation of the scale pits meets the double contingency principle as described in SAR Section 5.2.2.3. The NCSA provides controls for both mass and moderation with a 6 inch rather than 12 inch depth of the Raschig rings. The Raschig rings contribute to the effectiveness of the mass and moderation controls by increasing the quantities of uranium mass and moderator that would have to reach the pits for a criticality to occur, thereby making such accumulations clearly non-credible given the NCS controls imposed and process conditions present. Mass control is based on prevention of UF releases as described in the accident analysis SAR Section 4.2.3, which 6

concludes that the only credible scenario that could result in the large release of UF above the scale pits 6

with potential accumulation of UO F in the scale pits is a pigtail rupture (SAR Section 4.2.3.2)in which 22 liquid UF is released. Therefore, mass control is provided by TSR 2.5.3.4, Pigtail Line Isolation System, 6

which would limit the liquid UF release to s 127.5 pounds. Only a very small portion of this release of 6

l UF would reach the scale pits due to the rapid vaporization of the UF once exposed to the atmosphere; 6

6 approximately 60% goes to vapor and 40% to small particulate sclids that will disperse over the ERP area and the steel plate that covers the scale pit. Even ifit was possible for all of the 127.5 pounds UF /UO F 6

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GDP97-0075 Page 2 of 2 United States Enrichment Corporation (USEC)

Proposed Certificate Amendment Request Scale Pit Raschig Rings Detailed Description of Change to enter the scale pit the resultant depth would be.03 inches which is considerably less than the 3.6 inch

" geometrically favorable" slab depth for the plant maximum product enrichment of 10% in addition to the 6 inches of Ras;,hig rings. The Raschig ring depth of 6 inches is adequate to assure that even a liquid cylinder passive failure, a very unlikely event due to the quality and testing required of UF cylinders, would not add enough uranium to the pit to cause a criticality (15,000 lbs. would be required for pits l A j

and 2). As noted above, very little UF would enter the pit. Moderation control is based on the 6

unlikeliness for any significant quantities of water to be found in the scale pits. Moderation control is provided by the administrative control to inspect the scale pits weekly for water level. In addition, the steel plate that covers the scale pits also inhibits the flow of any water or UF into the scale pits. The 6

NCSA concluded that there were no credible accidents ir, which there would be a simultaneous release of enough uranium and water to the scale pits to result in a criticality with a 6 inch Raschig ring depth.

The conclusion of the NCSA is that the operation of the scale pits meets double contingency with a 6 inch rather than the 12 inch depth of Raschig rings. The Raschig rings enhance the effectiveness of the mass and moderation controls by increasing the quantities of uranium and moderator required to be present to support a criticality. The NCSA has determined that only 6 inches of Raschig rings are needed

- in scale pits 1 A and 2, as is the case for all of the other withdrawal station scale pits to provide double contingency.

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f-GDP97-0075 i

Page1of4 Proposed Certificate Amendment Request l

Portsmouth Gaseous Diffusion Plant l

Letter GDP97-0075 Removal / Insertion Instructions Remove Page Insert Page VOLUME 1 Section 3.2.2.4.6 Section 3.2.2.4.6 Pages 3.2-33/3.2-34 Pages 3.2-33/3.2-34 VOLUME 2 Sectirsa 4.2.2.2 Section 4.2.2.2 l

Pages 4.2-3/4.2-4 Pages 4.2-3/4.2-4 VOLUME 4 TSR 2.5.4.4 TSR 2.5.4.4 l

Page 2.5-24 Page 2.5-24 l

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TS51-PORTS PROPOSED May 16,1997 RAC 97X0147 (RO)

SECTION 2.5 SPECIFIC TSRs FOR X-326 ERP, X-333 LAW, AND X-330 TAILS WITIIDRAWAL STATIONS 2.5.4 GENERAL DESIGN FEATURES 2.5.4.3 UF, Cylinder Pigtails DF:

Newly fabricated pigtails are designed to withstand at least 400 psig j

SURVEILLANCE:

Frequency Surveillance Prior to initial use SR 2.5.4.3.1 Inspect and perform hydrostatic test at least to 400 psig and ensure inspection tag is attached to the pigtail BASIS:

Structural integrity of the pigtail significantly reduces the likelihood of a catastrophic rupture [SAR Section 4.2.3.2].

2.5.4.4 Scale Pit Raschig Rings DF:

ERP, LAW and Tails scale pits shall contain Borosilicate glass Raschig rings to a minimum l

depth of 6 inches.

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SURVEILLANCE:

Frequency Survei!!ance l

Annually SR 2.5.4.4.1 Verify that the surveillance requirements contained in ANSI Standard 8.5 are satisfied.

BASIS:

The scale pits contain Raschig Rings to enhance nuclear criticality safety [SAR Section 3.2.2.4.6 &

4.2.2.2].

2.5-24

SAR-PORTS PROPOSED May 16,1997 RAC 97X0147 (RO)

The scale pits in ERP, LAW and Tails are filled to a minimum depth of 6 inches with 1.5-inch borosilicate glass Raschig rings containing 4% boron. With the exception of the LAW Station, these pits have neither drains nor sump pumps. In the LAW Station, automatic sump pumps transfer any liquid accumulating in the scale pits to a reservoir tank. The scale pits in all three facilities are checked weekly for the presence of liquid. If more than one inch of water is detected, the pits are pumped. The LAW Station reservoir tank is also inspected weekly. If liquid is found in the tank, it is pumped and analyzed before disposal. If the liquid contains more than 5 grams of U-235 per liter, the solution is drained into 5-inch polybottles and stored in approved container holders.

3.2.2.4.7 High Vent Header Pressure Alarm The plant auxiliary feed and vent return headers are normally used to supply UF and to vent the withdrawal station to its withdrawal point. Most likely, the withdrawal point will be located in the X-330

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Building, requiring the use of building tie-lines and motor operated valves. High vent header pressure alarms are provided for each compression loop to warn of high vent header pressure, which could result from inadvertent closing or a misvalving operation in the stauon's vent return header. This PBS when actuated sounds an alarm when the vent header pressure reaches 7.5 psia.

3.2.2.4.8 High Discharge Pressure Protection for First Stage Campressor i

At ERP and LAW, the instrumentation which provides for the high pressure venting (HPV) on each compressor loop is located in the recycle line of the first stage compressor. It consists of two pressure switches (PSH and PSHH), each with an accuracy of 0.1 %. The PSH is set at 7.5 psia and activates both audible and visual alarms locally and in the ACR. If the PSHH is allowed to be energized (10 psia), the HPV circuit will become energized, isolating the affected loop and venting it to the cascade. These alarms serve two purposes. The PSH (7.5 psia) provides a warning the operator of the accumulation of light molecular weight material (" lights") in the cendensers, accumulators, and product cylinder. Usually

" lights" accumulate slowly causing a gradual incase in the compressor discharge pressure. At 7.5 psia, j

the compressors are experiencing high discharge pressure and are nearing a critical operating region where i

sudog could begin. When this alarm is actuated, immediate investigation and corrective action by the orarator are necessary.

l Tie PSHH is set at 10 psia so that automatic HPV, isofation and venting will occur if a break in l

l process piping occurs, total seal failure occurs, or a process gas cooler ruptures allowing a large volume 1

l of coolant to enter the compression loop The lighter gases cause a decrease in compressor discharge l

pressure and an increase in compressor suction pressure resulting in automatic HPV and isolation.

However, this PSHH would not protect the compression loop from overpressurization due to instrument i

failure or recycle failure. The PSH and PSHH are calibrated annually.

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SAR-PORTS September 15,1995 Rev.1

3.2.2.4.9 Coolant Sntem Protection The coolant system has the same high pressure protection as previously described for process cells

. (Section 3.1.1.2.5). When the compressor motors are tripped due to high coolant pressure, the MOVs automatically close (ERP and LAW only).

The ERP station coolant system is protected against a drop in R-114 pressure by a pressure switch which closes an MOV in the water inlet line if the R-114 vapor header pressure drops below 70 psia. If the differential pressure between the R-114 vapor header and the' water side of either condenser drops to approximately 5 psi, the compressors are tripped.

The.meletron, described in Section 3.1.1.2.7.2, is set to trip the compressor at 100 psia coolant pressure. (LAW and ERP only) 3.2.2.4.10 Buffer Systems The monitoring and control panels for the buffer systems in the high pressure withdrawal facilities 1

provide'a means ofidentifying failures in compressor flanges, compressor discharge flanges, valve bonnets and bellows, and double wall expansion joints. An alarm is provided both locally and in the ACR when a component failure occurs. This permits adequate time for timely isolation and replacement of failed or damaged components.

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Due to the pressure extremes across a compression / liquefaction loop, two systems are employed to j

supply the appropriate amount of buffer gas to these components. The high pressure control panel provides 1

buffer gas at 25 psig to all buffered components after the second stage of compression. The low pressure control panel supplies 10 psig buffer gas to all the components operating below atmospheric pressure. See Figure 3.2-12E.

The G-17 valves that are located in the high pressure section of the loop can experience pressures ranging from 0.2 to 40 psia. To prevent the valve bellows differential rating of 32 psia from being exceeded when the systems are evacuated, and yet provide adequate purge pressure during normal operation, instrumentation has been installed to switch the buffer pressure from 25 psig to 10 psig or vice

- versa when the valve body pressure reaches 20 psia. See Figure 3.2-12F. A revised, variable pressure, buffer system is scheduled for installation in 1995 and 1996 under CWIP Project 34470.

Dry air is supplied from the 100 psig plant air header through a filter and a pressure reducing valve for each monitoring and control panel. After the pressure reduction, a relief valve is provided to prevent overpressuring of the system. Normally, the buffer gas will pass through an orifice; but if the required

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flow is greater than the orifice can supply, a wedle valve can be opened to supply additional buffer gas.

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If a component failure occurs, requiring a much larger amount of buffer gas, a check valve will open to 1

permit the required amount of gas to enter. Another check valve has been installed to relieve excess pressure caused when opening a G-17 valve. When a G-17 valve opens, the valve bellows collapses causing an increase in pressure in the line. From the main monitoring and control panels the 3.2-34 1

5 SAk-PORTS PROPOSED May 16,1997 RAC 97X0147 (RO) requirements for assay monitoring (laboratory samples or automatic systems), and verification that withdrawals are made into the proper cylinders provide assurances that the probability of the occurrence of a criticality at these facilities is extremely low.

The nuclear criticality safety review determined that the reservoir was nuclearly safe for an assay of 5 % U-235 and that two or more contingencies or failures would be required for the reservoir to be unsafe at 10% assay. Double contingency is ensured by appropriate mass and moderation controls identified in the NCSA. As described in Section 3.2.2.4.6, the scale pits are filled to a minimum depth of 6" at LAW, Tails, and ERP with 1.5-inch borosilicate glass Raschig rings containing 4% boron.

4.2.2.3 Criticality in X-326 Top Case C-22 Criticality at Product Withdrawals and HASA-The high-assay UF withdrawn at the PW, Line Recorder Manifolds, and Interim Surge / Purge is capable of criticality if an unsafe mass is allowed to accumulate. Local Control Center (LCC) withdrawal quantities are too small to achieve criticality, even at high assay cells. To prevent a criticality at high-assay solid condensation withdrawals, product withdrawals and cylinders are designed with limiting dimensions defined by nuclear safety. To prevent a criticality due to operator error and cylinder mishandling, cylinder handling carts and equipment and administrative controls assure compliance with safe handling procedures.

However, operator negligence, resulting in an unsafe configuration of product cylinders and equipmert, or process failure resulting in the accumulation of an unsafe mass can result in criticalities. These incidents can be modified slightly by introducing a moderator, usually water, which rMuces the amount of enriched uranium required to form an unsafe mass.

Operator error is the only credible cause for criticality; the operator would have to totally disregard operating procedures that restrict the placement of 5 inch and 8-inch UF, cylinders in always-safe spacing.

However, the probability of operator error of gathering a sufficient number of cylinders to form a critical -

assembly is extremely low. Data from critical experiments performed at Oak Ridge, sununarized in Table 4.2-2 shows that twelve air-reflected cylinders (3 x 4 array) or four fully reflected (concrete) cylinders (1 x 4 or 2 x 2 arrays) are required for criticality. Smaller cylinder arrays can be made to go critical, but the reflection requirements are even more exotic than those for the 1 x 4 or 2 x 2 arrays. The smallest critical assembly for 8-inch cylinders containing Very High Enriched (VHE) material has been calculated as two cylinders; if the two cylinders are lying side by side on 12 inches of concrete and covered by 1 foot of water. It is not a credible scenario to have sufficient water and two cylinders in contact in a volume large enough to hold the cylinders and water. The probability of creating a larger critical array of cylinders is extremely low because of operator training, direct supervision, transport equipment design, and the limited number of cylinders available. The probability of natural phenomena to rearrange the limited number of

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cylinders into a critical configuration is also extremely low.

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5 SAR-PORTS J:muary 19,19%

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- This brief analysis is sufficient to dismiss criticality in cylinders as a potential accident for high-assay solid condensation withdrawals. However, dismissing these small probabilities and allowing the occurrence of a criticality with 5 x 10'7 fissions as the expected critical accident, the two' operators, required to be present by the administrative buddy system, could be killed by direct radiation and several other persons

- could receive up to 100 rem. Most of the UF. involved and all of the fission products would be released because the cylinder (s) would rupture. Cylinder rupture resulting in material dispersion should prevent fission rebursts. The consequences would be considered medium and the risk would be extremely low.

4.2.2.4 Criticality in the X-344A SNM Vault Case C-23 CJiticality in X-344A Due to Imnroner Cylinder Handling -

The occurrence of a nuclear excursion is possible in the X-344A Vault if the always-safe space requirements are simultaneously ignored by at least two operators. A more detailed analysis of this criticality is contained in Appendix C. A criticality will actuate the radiation alarm in the vault, resulting in the evacuation of X-342A, X-344A, X-344B, X-lO8H, and X-630-1. The estimated acute radiation doses for personnel in and near the vault are shown in Table 4.2-3. The locations of the personnel listed in the table are shown in Figure 4.2-1.

Because initiation of a critical reaction requires simultaneous multiple errors by at least two persons, i

the probability of occurrence in the X-344A Vault is considered extremely low. The consequences are considered medium. The risk is extremely low.

l 4.2.2.5 Criticality in the X-345 SNM Storage Facility 1

Case C-24 Criticality from Accidental Geometry Change A nuclear accident having the greatest impact on those exiting through the constrained path occurs in X-345 during the loading and unloading of eight constrained containers which are transported on a cart between the vault and the storage and drum area. The cart has eight cylindrical holders with a metal extension of at least two feet center to center. The containers are set in the holders and are secured with a chain at the top of the holder. Administrative controls limit the number of containers in motion to one, at any one time. During inventory two containers are allowed in motion at one time, one in each half i

vault. Activities performed in the work and drum storage area are to conform to procedures approved by Criticality Safety staff. A criticality alarm system ensures that operating personnel would be rapidly alerted to a nuclear criticality.

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~ An accident scenario is assumed in which a forklift knocks over the cart which holds a group _of l

_ containers in the south vault of Building X-345. The containers assemble in an unsafe geometry about two j-feet from the west wall and 25 feet from the south wall, resulting in a critical reaction. This generates a single radiation burst of about 10'7 fissions. One of the containers ruptures, causing some of the reaction

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products to become airborne. At the time of the accident, employees are stationed as shown in Figure 4.2-l

2. Their distances from the reaction and the prompt radiation doses they receive are shown in Table 4.2-4.

The radiation triggers the alarm clusters in X-345 and in all the adjacent 4

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GDP97-0075 Page1of3 United States Enrichment Corporation (USEC)

Proposed Certificate Amendment Request Scale Pit Raschig Rings Significance Determination The United States Enrichment Corporation (USEC) has reviewed the proposed changes associated with this certificate c.mendment request and provides the following Significance Determination for consideration.

1. No Significant Decrease in the Effectiveness of the Plant's Safety. Safeguards or Security Programs The Raschig ring design feature for the Withdrawal Station scale pits is not addressed in plant safet;, safeguards or security programs contained in Volume 3 of the Application for United States Nuclear Regulatory Commission Certification for the Portsmouth Gaseous Diffusion Plant. Therefore, the etTectiveness of these programs is unaffected by these changes.

2. No Significant Change to Anv Conditions to the Certificate of Comnliance None of the Conditions to the Certificate of Compliance for Operation of Gaseous Diffusion l

Plants (GDP-2) specifically address design features or their related surveillances. Thus, the proposed change has no impact on any of the Conditions to the Certificate of Compliance.

3. No Sienificant Chance to Any Condition of the Anoroved Comnliance Plan l

l Reducing the required depth of Raschig rings in the ERP 1 A and 2 scale pits from 12 inches to 6 inches is not addressed by the Compliance Plan nor in any conditions of the Compliance Plan.

Therefore, revision of TSR 2.5.4.4 does not change any condition of the approved Compliance l

Plan.

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4. No Significant increase in the Probability of Occurrence or Conseauences of Previousiv Evaluated Accidents The revision of TSR 2.5.4.4 to reduce the required depth of Raschig rings in the ERP 1 A and 2 scale pits from 12 inches to 6 inches will not increase the probability of occurrence or consequences of any postulated accident currently identified in the SAR. The operation of the scale pits meets double contingency with a 6 inch depth of Raschig rings, therefore the reduction in Raschig ring depth from 12 inches to 6 inches will not change any condition assumed in the accident analysis.

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GDP97-0075 Page 2 of 3 United States Enrichment Corporation (USEC)

Proposed Certificate Amendment Request Scale Pit Raschig Rings Significance Determination

5. No New or Different Tyne of Accident The revision ofTSR 2.5.4.4 to reduce the required depth of Raschig rings in the ERP 1 A and 2 scale pits from 12 inches to 6 inches will not create a new or different type of accident than those previously analyzed. The change will not add any new accident initiator and the double contingency requirements will remain in place as specified in the applicable NCSA.

6. No Significant Reduction in Margins of Safety The requirement to have Raschig rings as a design feature will not be changed as a result of this TSR revision. The requirements necessary to ensure double contingency will remain in place j

as specified in the applicable NCSA. Therefore, this change will not reduce the margin of safety associated with this TSR.

7. No Significant Decrease in the Effectiveness of any Programs or Plans Contained in the Certificate Annlication The Raschig ring design feature is not specifically addressed in any programs or plans contained in the Certificate Application. Therefore, the revision of TSR 2.5.4.4 to reduce the required depth of Raschig rings in the ERP 1 A and 2 scale pits from 12 inches to 6 inches will not decrease the effectiveness of these programs or plans.

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8. The Pronosed Changes do not Result in Undue Risk to 1) Public Health and Safety. 2) Common Defense and Security. and 3) the Environment.

The revision of TSR 2.5.4.4 to reduce the required depth of Raschig rings in the ERP 1 A and 2 scale pits from 12 inches to 6 inches does not increase the probability or consequence of any previously analyzed accident. The requirements necessary to ensure double contingency will l

remain in place as specified in the applicable NCSA. In addition criticality accidents for which y

this design feature is intended to prevent are local events. This change has no impact on plant effluents or on the programs and plans in place to implement physical security. As such, this change does not represent an undue risk to public health and safety. Therefore, this change will have no adverse impact on the environment or the common defense and security.

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GDP97-0075 j

Page 3 of 3 United States Enrichment Corporation (USEC) l Proposed Certificate Amendment Request Scale Pit Raschig Rings Significance Determination

9. Ihsre is no Change in the Tynes ; r Significant Increase ia the Amounts of any Effluents that may be Released Offsite.

i This change has no effect on the generation or disposition of effluents, therefore, it does not change the types or amounts of effluents that may be release offsite.

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10. There is no Significant Increase in Individual or Cumulative Occunational Radiation Exoosure.

The consequences of a criticality associated with any postulated accident currently identified in the SAR will not increase as a result of decreasing the level of Raschig rings in the scale pits.

This change does not increase the probability of a criticality in the scale pits. The Raschig ring depth in the scale pits does not affect the radiological protection program actions in place to minimize occupational exposures. Therefore, there is no increase in individual or cumulative occupational radiation exposure as a result of this proposed change.

I1. There is no Significant Construction Imuact.

This change does not involve a plant modification, therefore it will not impact construction.

12. Ihere.is no Significant Increase in the Potential for Radiological or Chemical Consecuences from Previousiv Analyzed Accidents.

The revision of TSR 2.5.4.4 will not increase the probability of occurrence or consequences (radiological and/or chemical) of any postulated accident currently identified in the SAR. The i

decrease in the Raschig ring depth from 12 inches to 6 inches in the scale pits does not alter the assumptions used in the accident analysis since the double contingency principle is satisfied by the identified mass and moderation controls. Therefore, there is no significant increase in the potential for radiological or chemical consequences from previously analyzed accidents.

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