ML20140C009

Submits TAR Re Review of Certificate Amend Request for Reducing Scale Pit Raschig Ring Depth from 12 to 6 Inches at Portsmouth Gaseous Diffusion Plant (Ports).W/Nuclear Criticality Safety Approvals

ML20140C009
Person / Time
Site:	Portsmouth Gaseous Diffusion Plant
Issue date:	06/02/1997
From:	Pierson R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Ting P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
TAC-L32032, NUDOCS 9706090076
Download: ML20140C009 (76)

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UNITED STATES g

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' 4" NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20686-4001

\*****/ June 2, 1997 MEMORANDUM TO: Philip Ting, Chief Operations Branch ,

Division of Fuel Cycle Safety and Safeguards FROM: Robed C. Pierson, Chief 1

( l' Special Projects Branch Division of Fuel Cycle Safety and Safeguards ,

SUBJECT:

TECHNICAL ASSISTANCE REQUEST - REVIEW OF CERTIFICATE AMENDMENT REQUEST FOR REDUCING SCALE PIT RASCHIG RING i

- DEPTH FROM 12 TO 61NCHES AT PORTSMOUTH GASEOUS DIFFUSION PLANT (PORTS) l

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The Special Projects Branch requests technka assistance in reviewing the following project.

i Project: USEC certificate amendment request (CAR), dated May 16,1997, to reduce the  !

minimum depth of Borosilicate glass Raschig rings in the product withdrawal cylinder scale pits from 12 inches to 6 inches.

Casework /RITS/ TAC Nos: 70-7002130S/212AM/L32032 Reauested Action: The Design Feature (DF) requirement of Technical Safety Requierment (TSR) 2.5.4.4 states., " Scale pits shall contain Borosilicate glass Raschig rings to a nominal depth of 12 inches at ERP (positions 1 A and 2),6 inches at ERP (position 18) and 6 inches at LAW / TAILS."

According to USEC, updated Nuclear Criticality Safety Evaluations (NCSEs) and Nuclear Criticality Safety Approvals (NCSAs) have determined the minimum acceptable depth to be 6 j

inches for all withdrawal stations. Consequently, USEC has proposed revising the DF to read as follows:"ERP, LAW and Tails scale pits shall contain Borosilicate glass Raschig rings to a l

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minimum depth of 6 inches." )

After discovuing the discrepency between the actual minimum Raschig ring depth at tne ERP-2 station and the minimum depth required by TSR 2.5.4.4, PORTS took that station out of service.

Attempts to fill the scale pit with Raschig rings to a minimum depth of 12 inches resulted in interference with proper scale operation. As such, USEC has requested the NRC to give top priority to this CAR since they would like to bring the ERP-2 withdrawal station back into service as soon as possible.

The SPB target date for completion of this amendment is July 31,1997. To meet this target date, completion of your review in the form of recommendations based on independent 1 confirmatory criticality computer code evaluations is requested by June 30,1997. In addition, the  !

estimated schedule accounts for at least one request for additional information (RAI) to be l

generated by the primary reviewer no later than June 13,1397. If needed, a meeting with USEC on this subject could also be arranged before sending them our RAI. j l

9 ros 9706090076 970602 NRC HLE CENTER COPY I

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-2 June 2, 1997 l Philip Ting A copy of the CAR (Enclosure 1) and the pertinent NCSAs and NCSEs (Enclosure 2) are j attached. Yawar Faraz has already discussed this request with Jack Davis of your staff.

I However, if anoiner reviewer is assigned, please have him directly contact Mr. Faraz before June 3,1997, to further discuss this request.

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! Contacts: PM: Yawar H. Faraz,415-8113 LA: D. Amy Hoadley, 415-8129 1

Please provide the information requested below and retum a completed copy to the Licensing Assistant (LA) or Project Manager (PM) before June 3,1997.

- Name of Reviewer: 3ACK 2 CSl//5 FCOB's Projected Completion Date: S20!f/

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FCOB Branch Chief Signature; -41 /m, ,3 The above TAC No. should be referenced in future correspondence related to this request and on the RITS Report for recording staff time expended on this effort.

Docket 70-7002 Certificate GDP-2 Attachment 1: 5/16/97 Itr frm James H. Miller, USEC to C. J. Paperiello l Attachment 2: NCSA-0326_015.A02 tequ3st date 5/2/97 l NCSA-0330_007.A00 request date 11/19/96 l NCSA-0333_017.A00 request date 10/23/96 Docket 70-7002 i

! G:\ TAR 3130S YHF i j DISTRIBUTION: *w/o attachment (Control No: 130S) l Docket 70-7002 NRC File Center - PUBLIC SPB r/f i *FCSS r/f *NMSS r/f *CCox, Rlli *GShear, Rill

• MHom *JDavis, FCOB *WSchwink, FCOB *DHeartland, Rill l n l OFC SPB C- SPS JPA SPEP)

NAME YFaraz:ij N Dhadley? [ frtin Fherson DATE F /30/97 b/97 [ 64/97 /9/97 C = COVER E = COVER & ENCLOSURE N = NO COPY OFFICIAL RECORD COPY l

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70 '700b UnitId States Ennchment Corporation 2 Democracy Center 6903 AockledgeDrive Bethesda. MD 20817 Tel (3011564-3200 Fax (3011564-3201 l tiileil Males Etirirlittletit Citpitalitett 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 l 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:

l In accordance with 10 CFR 76.45, the United States Enrichment Corporation (USEC or Corporation) j hereby submits a request for amendment to the cenificate of compliance for the Portsmouth, Ohio  !

Gaseous Diffusion Plant (GDP). This certificate amendment request revises TSR Section 2.5.4.4 Scale l

Pit Raschig Rings, to reflect that the ERP scale pit positions l A and 2 require only 6 inches of Raschig j rings instead of the 12 inches as previously stated to enhance nuclear criticality safety. Once revised, the 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".

1 UF, cylinders are filled directly above the scale pits at the withdrawal stations. Quantities of uranium l

could accumulate in the scale pit if a release were to occur. Should this accumulated mass of uranium l

become fully moderated a criticality could occur. The Raschig rings are used in the scale pits to increase  ;

the mass of uranium and moderator required to accumulate in the scale pits for a criticality to occur. Six inches of Raschig rings is adequate to assure tha' accumulation of enough uranium and moderator (water)

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j in the pit for a criticality to occur is not credible based on the contingency controls identified.  ;

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-9705220205- 970516 goa aoocxo7oo=2 -n. 44141411011LaIQIl 'i' l

Cffices en Paducah. Kentucky Portsmouth. Ohio Washington. DC

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l Dr. Carl J. Paperiello May 16,1997 GDP 97-0075 Page 2 Enclosure I 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 l SAR pages. The TSR page is provided for your review and approval. The revised SAR 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 l only. These revised SAR pages reflect revisions associated with this certificate amendment request and l may not reflect other approved changes to tnese SAR pages. Enclosure 3 contains the basis for USEC's l 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

! limited space available within the scale pit. For ERP position 1 A, the change in Raschig ring depth is l requested so that the depth of Raschig rings at this ERP position is consistent with the depth of Raschig l 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, i 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, l mes H. Miller j Vice President, Production l

Enclosures:

As Stated cc: NRC Region 111 Office NRC Resident inspector - PGDP NRC Resident inspector - PORTS DOE Regulatory Oversight Manager

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j , OATil AND AFFIRMATION  !

.1. 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 i

Regulatory Commission this Certificate Amendment Request for the Portsmouth Gaseous Diffusion (

, i l Plant, that I am familiar with the contents thereof, and that the statements made and matters set forth l i

! r j therein are true and correct to the best of my knowledge, information, and belief.  :

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James H. Miller i

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Subscribed to before me on this lN day of & &' ,1997.

U MAAA. m ary Public W . Nr. MONTOYA McKOY NOfARY PUBUC STATE OF MARytMe My " '

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Enclosure 1 i

GDP97-0075 Page1of2 I

United States Enrichment Corporation (USEC) i Proposed Certificate Amendment Request Scale Pit Raschig Rings l

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 1 A and 2). 6 inches at ERP(position IB) and 6 inches at LAW / TAILS" to "ERP, LAW and Tails scale pits shall contain Borosilicata alass Raschig rings to a minimum depth of 6 inches.". SAR Sections 3.2.2.4.7 and 4.2.2.2 will also be revised to reflect that only 6 inches of Barosilicate 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 ses due to the limited space available in the scale pit. In addition, the number 1 A ERP scale pit will only be filled with 6 inches of Raschig rings to avoid inconsistencies with the otiier 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 concludes that the only credible scenario that could result in the large release of UF6above the scale pits with potential accumulation of UO2F2in the scale pits is a pigtail rupture (SAR Section 4.2.3.2)in which liquid UF 6is released. Therefore, mass control is provided by TSR 2.5.3.4, Pigtail Line Isolation System, which would limit the liquid UF 6release to s 127.5 pounds. Only a very small portion of this release of i UF. would reach the scale pits due to the rapid vaporization of the UF. once exposed to the atmosphere; approximately 60% goes to vapor and 40% to small particulate solids that will disperse over the ERP area i

and the steel plate that covers the scale pit. Even ifit was possible for all of the 127.5 pounds UF,/UO F r

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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 Raschig 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 UF6 cylinders, '

would not add enough uranium to the pit to cause a criticality (15,000 lbs. would be required for pits I A and 2). As noted above, very little UF6 would enter the pit. Moderation e-trol is based on the l 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 tne flow of any water or UF6 into the scale pits. The ,

NCSA concluded that there were no credible accidents in which there would be a simultaneous release 1 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 I A and 2, as is the ca ' for all of the other withdrawal station scale pits to provide double  ;

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Enclosure 2 GDP97-0075 Page1of4 -

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i Proposed Certificate Amendment Request l Portsmouth Gaseous Diffusion Plant Letter GDP97-0075 Removal / Insertion Instructions i

Remove Page Insert Page VOLUMEI Section 3.2.2.4.6 Sectiva 3.2.2.4.6 Pages 3.2-33/3.2-34 Pages 3.2-33/3.2-34 VOLUME 2 Section 4.2.2.2 Section 4.2.2.2 Pages 4.2-3/4.2-4 Pages 4.2-3/4.2-4 VOLUME 4 l l l TSR 2.5.4.4 TSR 2.5.4.4 l Page 2.5-24 Page 2.5-24 l

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TSIbI' ORTS PROPOSED May 16,1997 RAC ')7X0147 (RO) ,

SECT ION 2.5 SPECIFIC TSRs FOR X-326 ERP, X-333 LAW, AND X-330 TAILS WITIIDRAWAL STATIONS l 2.5.4 GENERAL DESIGN FEATURES l

2.5.4 3 UF. Cylinder Pigtails l

DF: Newly fabricated pigtails are designed to withstand at least 400 psig SURTILLANCE:

Frequency Surveillance Prior to initiai 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 BAS S:

Struaural integrity of the pigtail significantly reduces the likelihood of a catastrophic rupture [SAR Secti in 4.2.3.2].

2.5.. 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. l SURVEILLANCE:

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

B/ SIS:

Tl e scale pits contain Raschig Rings to enhance nuclear criticality safety [SAR Section 3.2.2.4.6 & ,

4.2.2.2].

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

The scale pits in ERP, LAW and Tails are filled to a minimuni 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 putnped 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 Building, requiring the use of building tie-lines and motor operated valves. liigh 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 station'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 Comoressat 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 L The PSH is set at 7.5 psia and activates both audible and visual alarms 'ocally and in the ACR. If the PSHil 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 condensers, accumulators, and product cylinder. Usually

" lights" accumulate slowly causing a gradual increase in the compressor discharge pressure. At 7.5 psia, the compressors are experiencing high discharge pressure and are nearing a critical operating region where surging couM begin. When this alarm is actuated, immediate investigation and corrective action by the operator are necessary.

The PSHH is set at 10 psia so that automatic HPV, isolation and venting will occur if a break in process piping occurs, total seal failure occurs, or a process gas cooler ruptures allowing a large volume of coolant to enter the compression loop. The lighter gases cause a decrease in compressor discharge pressure and an increase in compressor suction pressure resulting in automatic HPV and isolation.

However, this PSilH would not protect the compression loop from overpressurization due to instrument 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 O plant System Protection The coo' nt system has the same high pressure protection as previously described for process cells (Section 31.1.2.5). When the compressor motors are tripped due to high coolant pressure, the MOVs automaticall.; close (ERP and LAW only).

The ERI station coolant system is protected against a drop in R-Il4 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 differenti u pressure between the R-114 vapor header and the water side of either condenser drops to approximate y 5 psi, the compressors are tripped.

The me : tron, described in Section 3.1.1.2.7.2, is set to trip the compressor at 100 psia coolant pressure. (l.AW and ERP only) 3.2.2.4.10 luffer Systems The me titoring and control panels for the buffer systems in the high pressure withdrawal facilities provide a m ans of identifying failures in compressor flanges, compressor discharge flanges, valve bonnets and bellows and double wall expansionjoints. An alarm is provided both locally and in the ACR when a componer; failure occurs. This permits adequate time for timely isolation and replacement of failed or damaged cc uponents.

Due to he pressure extremes across a compression / liquefaction loop, two systems are employed to supply the :apropriate amount of buffer gas to these comp nents. The high pressure control panel provides buffer gas : . 25 psig to all buffered components after the second stage of compression. The low pressure control pan 1 supplies 10 psig buffer gas to all the components operating below atmospheric pressure. See Figure 3.212E.

The G 17 valves that are located in the high pressure section of the loop can experience pressures ranging fr m 0.2 to 40 psia. To prevent the valve bellows differential rating of 32 psia from being exceeded vhen the systems are evacuated, and yet provide adequate purge pressure during normal operation, .nstrumentation has been installed to switch the buffer pressure from 25 psig to 10 psig or vice versa whe i the valve body pressure reaches 20 psia. See Figure 3.2-12F. A revised, variable pressure, buffer sys :m is scheduled for installation in 1995 and 1996 under CWIP Project 34470.

Dry a r is supplied fro n the 100 psig plant air header through a filter and a pressure reducing valve for each r onitoring and control panel. After the pre sure reduction, a relief valve is provided to prevent overprest iring of the system. Normally, the buffer gas will pass through an orifice; but if the required flow is gi ater than the orifice can supply, a needle valve can be opened to supply additional buffer gas.

If a com; snent failure occurs, requiring a much larger amount of buffer gas, a check valve will open to permit ti. 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 I causing i a increase in pressure in the line. From the main monitoring and control panels the 3.2-34 l

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SAP;-PORTS PROPOSED May 16,1997 l 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 l 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.

liowever, operator negligence, resulting in an unsafe configuration of product cylinders and equipment, 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 reduces 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 summarized 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 I 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 I foot of l water. It is not a credible scenario to have sufficient water and two cylinders in contact in a volume large I 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 cylinders into a critical configuration is also extremely low.

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t SAR-PORTS January 19,1996 Rev.2 I l This brief ana' < sis is sufficient to dismiss criticality in cylinders as a potential accident for hia,h-assay solid condensatiori withdrawals. However, dismissing these small probabilities and allowing the occurrence of a criticality wi a 5 x 10" fissions as the expected critical accident, the two operators, required to be present by the adr mistrative buddy system, could be killed by direct radiation and several other persons could receive up t i 100 rem. Most of the UF. involved and all of the fission products would be released because the cylin er(s) would rupture. Cylinder rupture resulting in material dispersion should prevent fission rebursts. 3e consequences would be considered medium and the risk would be extremely low.

4.2.2.4 Criticah y in the X-344A SNM Vault Case C-23 Quh ility in X-344A Due to Imnroner Cylinder Handling The occurre ce 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 coat: ned in Appendix C. A criticality will acta.:e the radiation alarm in the vault, resulting in the evacuatiot of X-342A, X-344A, X-344B, X-lO8H, and X-630-1. The estimated acute radiation doses for persom :1 in and near the vault are shown in Table 4.2-3. The locations of the personnel listed in the table are s own in Figure 4.2-1.

Because initi tion of a critical reaction requires simultaneous multiple errors by at least two persons, the probability < L occurrence in the X-344A Vault is considered extremely low. The consequences are considered medi m. The risk is extremely low.

4.2.2.5 Critica 't3 ni the X-345 SNM Storage Facility Case C-24 Ch cality from Accidental Geometry Chanae A nuclear a ;ident having the greatest impact on those exiting through the constrained path occurs in X-345 during t: : loading and unloading of eight constrained containers which are transported on a cart between the vr it and the storage and drum area. The cart has eight cylindrical holders with a metal extension of at i ast two feet center to center. The containers are set in the holders and are secured with a chain at the te i of the holder. Administrative controls limit the number of containers in motion to one, at any one tim During inventory two containers are allowed in motion at one time, one in each half vault. Activiiit performed in the work and drum storage area are to conform to procedures approved by Criticality Safe e staff. A criticality alarm system ensures that operating personnel would be rapidly alerted to a nuclear er icality.

An accide- t scenario is assumed in which a forklift knocks over the cart which holds a group of containers in tia south vault of Building X-345. The containers assemble in an unsafe geometry about two feet from the s est wall and 25 feel from the south wall, resulting in a critical reaction. This generates a single radiator burst of about 10" fissions. One of the containers ruptures, causing some of the reaction products to laet )me airborne. At the time of the accident, employees are stationed as shown in Figure 4.2-

2. Their dista! ;es from the reaction and the prompt radiation doses they receive are shown in Table 4.2 4.

The radiation -iggers the alarm clusters in X-345 and in all the adjacent 4.2-4 1

Enclosure 3 GDP97-0075 Page1 of3 1

i United States Enrichment Corporation (USEC)

Proposed Certificate Amendment Request l Scale Pit Raschig Rings l

Significance Determination  !

The United States Enrichment Corporation (USEC) has reviewed the proposed changes associated I with this certificate amendment request and provides the following Significance Determination for consideration.

1. No Signi6 cant Decrease in the Effectiveness of the Plant's Safety. Safeguards or Security Programs

. l The Raschig ring design feature for the Withdrawal Station scale pits is not addressed in plant safety, safeguards or security programs contained m Volume 3 of the Application for United States Nuclear Regulatory Commission Certification for the Portsmouth Gaseous Diffusion Plant. Therefore, the effectiveness of these programs is unaffected by these changes.

2. No Significant Change to Any Conditions to the Certificate of Comolianes None of the Conditions to the Certificate of Compliance for Operation of Gaseous Diffusion Plants (GDP-2) specifically address desigra features or their related surveillances. Thus, the proposed change has no impact'on any of the Conditions to the Certificate of Compliance.

3. No Significant Chance to Any Condition of the Anproved Comoliance Plan 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 1 Plan.

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4. No Significant Increase in the Probability of Occurrence or Consecuences of Previously Evaluated Accidents.

l 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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United States Enrichment Corporation (USEC)

Proposed Certificate Amendment Request Scale Pit Raschig Rings Significance Determination ,

5. No New or Differe it Tvoe of Accident 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 create a new or different type of accident than those previously analyz d. The change will not add any new accident initiator and the double '

contingency requir :ments will remain in place as specified in the applicable NCRA.  ;

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6. No Significant Re =uction in Margins of Safety

)

The requirement t( have Raschig rings as a design feature will not be changed as a result of this 1 TSR revision. Th : requirements necessary to ensure double contingency will remain in place l as specified in the :pplicable NCSA. Therefore, this change will not reduce the margin of safety associated with th s TSR. {

i

7. No Significant E ecrease in the Effectiveness of any Proyrams or Plans Contained in the Certificate Anpli( diRD The Raschig ring lesign 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 Raschit rings in the ERP 1 A and 2 scale pits from 12 inches to 6 inches will not decrease the effe tiveness of these programs or plans.

8. The Pronosed CE nees do not Result in Undue Risk to 1) Public Health and Safety. 2) Common Defense and Sec, rity. and 3) the Environment.

The revision of"1 sR 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 anal) ed accident. The requirements necessary to ensure double contingency will remain in place t ; specified in the applicable NCSA. In addition criticality accidents for which l this design featu e is intended to prevent are local events. This change has no impact on plant l effluents or on t e programs and plans in place to implement physical security. As such, this l change does not epresent 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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Enclosure 3 GDP97-0075 Page 3 of 3 United States Enrichment Corporation (USEC)

Proposed Certificate Amendment Request Scale Pit Raschig Rings ,

Significance Determination ,

9. There is no Change in the Tvoes or Significant Increase in the Amounts of any Effluents that may be Released Offsite.

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.

10. There is no Significant Increase in Individual or Cumulative Occuoational Radiation Exoosure. l The consequences of a criticality associated wiui 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 Imoact. ,

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

12. There is no Significant Increase in the Potential for Radiolocical or Chemical Conseauences ,

from Previously 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 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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A-2975A# (8-9.8) l f

NUCLEAR CRITICALITY SAFETY APPROVAL 2.

- tsE nL4cK INK ONLY - O 2

PART As REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION PareIoft9 o TITLE: Extended-Range Product (ERP) Withdrawal Station h E

BUILDING; CC OPERATING AREA: DURAT10N- WORK REQ. s g '

X-326 ERP Station Permanent N/A u_

2

~

CRITICALITY ALARMS COVERAGE: ( X ) YES ( )NO Flss!ONABLE M ATERIAL DEsCRirr10N NUCLIDE (U-233. U-235. PU-239, etc.) Mass: FisSIONADLE NUCLIDE PERCENT:

U-235 l Not Limited Maximum 10%

FORM ANDCOMPGsfTION: UF. - gaseous liquid and solid sil!PPING. TRANSFER. AND PORTABLE CONTAINERS:

12" Diameter and 2.5.10 and 14 ton UF. cylinders

REFERENCES:

NCsA-PLANT 012 REFERENCE PREVIOUS NCs APPROVAL:

ORNLCsO.TM 284 NCsA-PLANT 006 CA 3605A OAT'GDP-1073 NCsA-PLANT 025 GAT.GDP 1074 NCsA-PLANT 036 NCsA 0326[015. A01 OAT DM-884 Rev. 2 NCsA PLANT 054 POEF-83196-1036 NCsA-PLANT 045 NP4-CO CA2344 (OM CA 5.5.2) NCsA-0326,014 NP4-CO-CA2345 (OM CA 5.5.4) NCsA-0705 039 g . I, .

NP4COCA1303(OM CA 5.5 6) NCSA 0326_015 E02 .

NP4-CO-CA2342 (OM - CA 5.5.7) / *' I NP4rO-CA2302(OM-CA6 6)and CA2340(OM-CA 5 5) l DESCRIPTION OF Tile Fiss!ON ABLE MATERI AL OPERATION:

The Extended-Range Product (ERP) withdrawal station is designed to remove gascous low-assay UF. product from the cascade, compress the gas, condense the gas to a liquid state via cooling, and drain the liquid into j product cylinders. These cylinders are moved to the ERP cooling yard and allowed to cool causing the UF.

to solidify. They are then moved to a storage area.

Station ERP-1B is currently out of serme Prior to starting station ERP-1B.NCS shall be notified and all l appropriate approvals and procedures will be updated.

He system is designed to permit the simultaneous withdrawal of UF, of two different assays into cylinders j of approved sizes. Loop ERP 1 of the ERP Withdrawal Station was designed to handle assays up to 100%

"5U and loop ERP 2 was designed to handle UF. assays up to 10% "5U. While the present maximum assay permitted at the ERP Withdrawal station is 10% "5U, typically both loops are run at lower assavs am to

" I k production requirements.

ORIG.IN A1 u UF. cylinder fill weight and the maximum weighted averaged enrichmi.~ im giinuers snalt be less than or equal to the values civen in Table 1 prior to removal of the cylinder from the scale cart.

4 Tills is ONLY A REQUEST. Tile LIMITS AND CONDITIONS IN PART B MUST BE READ. UNDERSTOOD. ACKNOWLEDGED. AND IMPLEMENTI D l REQUESTED BY: REQUEST APPROVED REQUEST DATE:

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3 Attachment 2

I NCSA-0326_015 A02

. A-2975 AC (8-94) _

NUCLEAR CRITICALITY SAFETY APPROVAL

- t!sE niacg INK ost.y .

PART A: REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION renezor:9

1. fYWTfNrTIM'  !

Table 1 Standard Fill Weight Limit and Maximum Weighted-Average Enrichments for Cylinders Used at the Low Assay Withdrawal Station Cylinder Serial Description Maximum Weighted  !

Model Number Fill Limit Average ,

(Pounds)t Enrichment

• Limitation (%)t

[

l 30A N/A 2%-ton 4,950 5.0 (concave) l 30B N/A 2%-ton 5,020 5.0 l l (co-ve x) 48A N/A 10-ton (heavy 21.030 4.5 l wall) l 48B(T) --

10-ton (thin 20,700 1.0 l wall) 48X* 1 TO 5000 10-ton (heavy 21,030 5.0(4.5) wall) 48F 9231 TO 14-ton (heavy 27,030 4.5 i 9660 wall) l l

I 48Y 9661 TO 14-ton (heavy 27,560 4.5 9999 wall) 48G(OM) 1TO 14-ton (thin 26,070 111820 wall w/ skirt) 4.5(l.0)  ;

111821 & 28,000 I ABOVE 48G(HX) 150001- 14-ton (thin 27,030 4.5(l.0) 151000 wall w/ skirt) 48G(H) 151001- 14-ton (thin 27,030 4.5(1.0) 15xxxx wall) t Weights are conservative to USEC-651, rev. 7.

t Enrichments in parenthesis are the limits given in USEC-651, rev. 7 for shipping.

• Properly identified 48X cylinders are allowed to a maximum 5% enrichment.

NOTE: If UF.is to be withdrawn with an average enrichment greater than 5% *U, a 12-inch or smaller cylinder shall be used. ,

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NCSA-0326 015.A02 i A 2975A# G-94) )

I l

NUCLEAR CRITICALITY SAFETY APPROVAL l

. (ISF. RIACK IN'E ONIX .

racesertsi l PART AEREQUEST FOR NUCLEAR CRITICALITY S FETY EVALNATION

.mmmm -

The ERP station is located on the ground floor of the northeast section of X-326. A mezzanine level I

above this ground floor space contains accumulators, valving, condensers, and piping supponing the withdrawal operation. The second floor contains the piping and valving that interface with the cascade l and draw the process gas into the ERP Withdrawal Station compressors and condensing system.

i There are two loops of equipment (ERP-1 and ERP-2) at the ERP Withdrawal Station. These loops i

are identical with the exceptions that the accumulators in loop ERP-1 are 4-inch I.D. and support two withdrawal positions while loop ERP-2 accumulators are 8-inch 1.D., and only support one withdrawal position.

i Figure 1 is a simplified flow diagram for loop ERP-1 of the ERP withdrawal station. Each ERP Station Loop can be supplied from various auxiliary service headers. Each loop normally , consists of an Allis-Chalmers AC 12-5 compressor, a cooler, a Worthington compressor, a condenser, two accumulators, and a withdrawal header. The product is withdrawn from the cascade as a gas, j l

! compressed in a two-stage process by two compressors to a temperature and pressure above the triple point, and then cooled to condense the gas to a liquid. The liquid product is drained from the accumulators to a withdrawal position. The liquid product is fed to UF cylinders at the withdrawal positions. The capability also exists to withdraw product into smaller cylinders than those listed in i Table 1.

i Each withdrawal position includes a scale and an air-operated cart used to move the cylinders between the withdrawal position scale and the cooldown erea immediately outside the building. All liquid-filled cylindets are cooled cutdoors in the cooldown bt to the east of the ERP station. A crane in the  ;

cooldown arca is used to lift the cylinders to and from the air-operated carts. l l

Although arrang:d as two loops, there is enough installed flexioility to allow many different flow paths li to meet the product demand or to accommodate equipment unavailability. In addition to the flexibility afforded by crossover piping, the ERP station includes a backup Worthington compressor that can be used as a second stage of compression in either loop.

l' The systems and equipment associated wbh loop ERP-1 of the ERP station are described in more detail i

below. The major system components are described first, and then suppon systems for those I i components are described. Except where noted, the equipment associated with loop ERP-2 is identical to loop ERP-1, and is operated in the same manner.

i l Comoressors The arrangement of compressors is illustrated in Figure 2.

A modified Allis-Chalmers AC 12-5 compressor normally provides the first stage of compression.

Process gas from a selected feed header flows to the AC compressor through a pressure control valve and an automatic isolation valve. The operator selects which header is be to used as the process gas

supply by opening a manual block valve at the header. The pressure control valve is used to controlj l

NCSA-0326_015.A02 l A-2975A0(8 94 ,

l NUCLEAR CRITICALITY SAFETY APPROVAL .

! 1.!SF, RIACK INK ONI.Y -

Fage 4 afI9 >

f PART A REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION MvwvfiM1 Dt '  ;

the pressure at the compressor inlet in order to control the withdrawal rate and to prevent surging of,

• t or high loads on, the compressor. The automatic isolation valve will close on an HPV isolation signal, isolating the ERP system from the header. This valve may also be closed at the discretion of the l

operator from the Local Control Room (LCR). The HPV isolation signal and functions are described in more detailin Section 10.

The AC compressor (or possibly a Worthington compressor) compresses the process gas from approximately 1-3 psia to 3-7 psia. To remove the heat of compression, the gas is cooled by a gas cooler. The R-Il4 coolant system which serves the gas cooler is described in Section 5.

1 The second stage of compression is supplied by a high speed Worthington (JS-697) centrifugal l l

l compressor. The Worthington comp'ressor c?mpresses the process gas from 3-7 psia to approximately 35 psia, with a dircharge temperature at approximately 350*F. This compressed gas is then fed to the l l

l condenser. In the event of a failure of a compressor, a spare compressor is available which may be used j j' by repositioning valves. l i

t l

i Each stage ofcompression has a recycle loop to adjust the system pressures and thus the flow rate to j the condenser. While the valves in the recycle loops can be operated under automatic control, they are typically operated under manual control.

The compressors include alarms on several out-of-tolerance conditions associated directly with the compressors or with the ERP system withdrawal loop. Compressor trips or alarms are provided for l

low lube oil pressure, high coolant pressure, low coolant / process gas difTerential pressure, high RCW

pressure, over-current, and under-voltage.

1 Double-walled expansionjoints are located on the suction and/or discharge lines of the compressors. j The space between the expansionjoint bellows is bu'rered and connected to the buffer monitoring and i l

alarm panel to provide immediate detection of expansion joint single-wall failure. The Buffer Gas System is described in Section 7. The compressor and motor bearings are lubricated by the Lube Oil System, which is described in Section 6.

The ERP station compressors are located inside a housing on the second floor. Thermostatically controlled electric heaters are used to control the heat in the compressor housing.

i 2. Condensers and Accumulators As illustrated in Figure 3, after second-stage compression, UF is cooled to a liquid state in a condenser.

The flow rate to the condenser is controlled by adjusting the compressor recycle valves.

The process gas is cooled from approximately 350*F to approximately 150*F in the condencer. The R-114 coolant system which serves the condenser is described in Section 5. The process gas condensers are cylindrical and are approximately 10-fe '-

l NCSA-0326_015.A02

.' A-2975 A# (8-94) l 1

NUCLEAR CRITICALITY SAFETY APPROVAL l

- USE RI,ACM INK ONIN -

I res,s .ris. I iPARTA I REQUEST FOR NUCLEAR CRITICALITY ammrm SAFETY EVALUATION'

~

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The nuclear criticality safety of equipment and operations handling liquid UF. is based on l moderation control which limits the H/U ratio to 0.088. This is done by limiting the pressure in l the condensers to less than 60 psia which ensures that the H/U ratio is s0.088. Noncondensible gases are vented from the condenser to the vent header via a pressure control valve.

I A two vessel accumulator is provided in each withdrawal loop. The ERP-1 accumulator has a volume of approximately 1100 pounds of UF.. The ERP-2 accumulator has a volume of approximately 2900

, pcunds of UF.. The inside diameter of the accumulators % 4 inches for ERP-1 and 8 inches for ERP-2.

The ERP-2 accumulators are insulated because they are not in a heated housing.

The discharge outlets of the two accumulators, in each withdrawal loop, arejoined and pass through l an isolation valve and a manually operated block valve to tne withdrawal manifold. A 3-position (Auto, l Open, and Close) switch, located on the outside wall of the withdrawal room, is present for each loop i

which controls the operational mode of the accumulator isolation valve. This switch is normally in the Auto position. The isolation valve automatically closes if the gamma spectrometer detects an assay outside of the limits of the target assay. In the event of a failure of the gamma spectrometer, this switch l is placed in the Open position. The gamma spectrometer is described in Section 9.

The ERP-1 condenser and accumulator are located in heated housings, as are the lower liquid distr;5utien headers. Only the ERP-2 condenser is located in a heated housing, its accumulator is located outside the housing. These housings and compressor housings are electrically heated and are  !

controlled thermostatically. The housings are known to currently have visible uranium contamination wl.ich will be removed during future maintenance activities.

A cross-tie line is present which allows the accumulator of one of the ERP Station loops to discharge to the other loop's discharge manifold. This line has double block valves, and one of these valves is physically locked closed when two different assays are being withdrawn at the ERP station. The sn block valve is left open to puvent pipe damage due to the thermal expansion of UF, in the heated line. l

3. Withdrawal Manifolds Each withdrawal manifold is equipped with several manually operated valves: ,

1

1) A block valve to discharge the liquid UF. to the withdrawal cylinder

2) Evacuation valves to remove UF. from the pigtail or to provide evacuation for any part of the i withdrawalloop

3) Nitrogen purge valve.

4) Cross tie valves which are kept locked closed, when withdrawing more than one assay, but l

! would allow the filling of cylinders at one withdrawal station from the other loop's accumulators.

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~. . .. - -.. - - . . . . -- . -..~ .

NCSA-0326_015. A02

'_ A 2975A0 m-94) .

l NUCLEAR CRITICALITY SAFETY APPROVAL ifM: HI,ACK INK ONIX .  ;

(PART AI REQUEST FOR UCLEAR CRITICALITY SAFETY EVALUATION ras 6.r s ifTW T fNf7 Dt l

The cylinder being filled is connected to the fill manifold via a pigtail. This pigtailis electrically heat l traced to prevent freezeout of the UF, in the pigtail. The cylinder valve is also electrically heated via a valve cap heater.

Each cylinder pigtail can be isolated by two air-operated valves in the case of a rupture. The cylinder safety valve (air-to-close)is attached to the cylinder valve while the manifold safety valve (air-to-open) is attached to the withdrawal manifold. If the two Pyrotronics System smoke detectors at a withdrawal

, position alarm, the control circuit will close the pigtailisolation valves at that position and turn off l

power to the heat tracing. A compressed air reser/oir is present in the system to ensure that compressed air is available to close the cylinder safety valve in the event of a loss of plant air.

4. Withdrawal Positions Cylinders being filled are mounted on air-operated carts. The air-operated carts offer a simple means of transpon between the withdrawal positions and the cooldown area that is accessed by crane.

eliminating the loading and unloading of cylinders directly on the scale platform. Compressed air is l

supplied to the air-operated can.

l A scale is provided at each of the three withdrawal positions. Digital readouts are provided at the scale.

l During the filling operation, the cylinder weight is moni:ored at least once every hour to ensure that l the cylinder is not ovedilled.

Each withdrawal position at the ERP station has its own scale pit which is covered with steel floor plates. The scale pits at two of the withdrawal positions (ERP-1 A and ERP-2) are approximately l

12-teet by 8.5-feet. Scale pit ERP-1 A has a depth of 72-73 inches and scale pit ERP-21.as a depth of l 50-5; inches. The scale pit for the third withdrawal position (ERT-1B) is approximately 11 feet 2 inches by 6.25-feet, with a depth of 47 % inches. All of the scale pits are filled to a minimum depth of j 6 inches with Raschig rings.

The three scale pits are inspected weekly for liquids. Ifliquid is found, it is sampled and analyzed for 2

2"U concentration. If the liquid contains more than 5 grams "U per liter, the solution is transferred l

into 5-inch maximum diameter polybottles and stored in approved container holders. If the solution is less than 5 grams2 "U per liter, the solution is transferred into unfavorable geometry containers or

! sent directly to the storm sewer.

i f

NCSA-0326_015.A02

A-2975 A# (8-94) i NUCLEAR CRITICALITY SAFETY APPROVAL

- USE RI,ACK INK ONLY -

PART A.: REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATIONrace 7 eris

^ imv7fMTDt Annualinspection of the Raschig ring depth is checked by using a measuring stick. The stick measures  ;

the distance from the top of the rings to the floor level. The following table indicates the acceptable depth of Raschig rings in the three pits and the associated maximum allowed stick measurement (i.e.  ;

the difference between the pit depth and the ring depth - a smaller stick measured value would indicate more rings). ,

Table 1. Raschig Ring Depth Chart at ERP Station l Maximum Required Maximum Allowed Stick Position Depth (in.) Raschig Rings (in.) Measurement (in.)

ERP-1 A 72 6 6'5 ERP-1B 47.5 6 41.5 ERP-2 50 6 44 At least eight locations in each of ti'e pits is checked, corresponding to the center of the cross-hatching formed by the 1-beams. Also, each of the inspection plates is checked at the center of the opc6mg.

If any one or more of the stations are removed from service for maintenance and the rings removed from the associated scale pits, the effected stat:ons are isolated from the process material Therefore, the unaffected stations are kept in serOe.

5 Coolant System The process gas stream is cooled after the first stage of compression to remove heat of compression. After second-stage compression, the UF. is cooled to a liquid state in a condenser.

Both the gas cooler and the UF condenser are served by one R-114 coolant system which is cooled by recirculating water (RCW). No pumps or compressors are used in these coolant systems.

The coolant pressure is maintained at least 5 psi above the UF, pressure to prevent UF from entering the coolant system, and at least 5 psi above the RCW pressure to prevent water from l entering the coolant system.

The protective devices for the cooling system include:

l

! 1. Pressure switch which alarms and closes the RCW supply valve on low R-114 pressure (70 psia) to prevent water from entering the R-ll4 side of the cooling system.

2. Pressure switch which alarms and also trips all process gas compressors on high R-114 l pressure (115 psia) to prevent Worthington compressor overheating.

3. Pressure switch which alarms and also closes RCW valve to maintain a differential pressure (5 psi) between the R-114 and RCW.

4. A rupture disc to prevent R-Il4 cooling system over pressurization.

NCSA-0326_015.A02

, A-2975A0 (8-94)

NUCLEAR CRITICALITY SAFETY APPROVAL J esE m.Arx isK ow.v . , j PART Al REQUEST FOR NilCLEAR CRITICALITY SAFETY EVALUATION rase ser as .

WYpWTfWTTIM I i

l

- 6. Lube Oi! System  !

l Lubricating oilis supplied to the AC compressors by the unit 27-1 Lube Oil System. Lubrication for the Worthington compressors are supplied by a dedicated oil system. Oil is supplied from an unfavorable geometry reservoir, pumped through an oil cooler, to the compressor and motor bearings. An alarm and compressor motor trip will occur on a low oil pressure. Refer to l NCSA-PLANT 054 " Lube Oil" -

7. Buffer Gas Systems i i

The monitoring and control panels for the buffer sys ems provide a means ofidentifying failures or leakage in compressor flanges, compressor discharge flanges, valve bonnets and bellows, and i double wall expansionjoints. An alarm is provided both locally and in the ACR when a component j t

failure occurs.

The bufTer gas is supplied at two pressures because of the large pressure differentials across the compression and condensation system. The high pressure bufTer panel provides gas at 35 to 40 psia j to all components after second stage compression and a low pressure panel supplies gas at 10 psig  ;

to the other components.

i l

The G-17 valves in the high pressure system cannot withstand the full range of differential pressures l that might be seen with a single source of buffer gas. The buffer gas is supplied to these valves at a l l variable pressure based on the process gas pressure. ,

8 Seal System The seal system provides dry, clean air and nitrogen to the compressor seals.  ;

The seal exhaust passes through alumina traps and is exhausted to the seal exhaust header. The alumina traps are constmeted of 5-inch, schedule 40 piping, and are approximately 5 foot long. The i alumina traps are spaced approximately 30-inches center-to-center. A safe boundary line is painted around the seal exhaust pumps and alumina traps. Alumina is removed by taking the top off the i trap and using a favorable geometry vacuum. Vacuum cleaner operations are covered in NCSA-PLANT 012. See NCSA-0326_014 for NCS controls on the seal exhaust.

9 Assav Monitorine Eouioment l

l The assay (enrichment) of the withdrawal for each loop is monitored with mass and gamma i

, spectrometers. The mass spectrometers automatically traps process gas from the AC compressor cooler discharge, analyzes the gas, and records the assay every five to six minutes. Each hour, an j operator records the current assay on the withdrawal data sheet. l

l NCSA-0326_015 A02 ,

A 2975A0(8-94) '

i NUCLEAR CRITICALITY SAFETY APPROVAL -

. use nuru exx osix-  ;

i PART As REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION- I'ne s.r s f anwmm j i

The gamma spectrometer monitors the flow to the withdrawal manifold with probes on the liquid j line before it enters the manifold. The assay is recorded on terminals at 5 to 6 minute intervals. If i the assay exceeds the predetermined assay set point for a cylinder size, the air-operated valve

, located between the accumulator and the withdrawal manifold is signaled to close. Due to an i l internal algorithm, the gamma spectrometer will not respond until the actual assay value is +0.05 above the set point value. U-tube samples are also taken at least every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> as a redundant means of assuring correct assay. When the gamma and mass spectrometers are out of service.

l. laboratory samples are collected and analyzed for assa" every 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> with assay results available j within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. l l i 10 High Pressure Venting (HPV) Isolation ,

l  :

The ERP station has high pressure venting (HPV) circuitry to relieve the system pressure in case of emergency. If the HPV circuitry is actuated a control valve in the compression loop automatically l opens and vents back to the vent return header, the flow control valve (s) to the condenser close, the condenser vent valve closes, the air-operated manifold isolation valve on the cylinder pigtail closes, ,

and the first-stage compressor suction valve closes. i l

The HPV circuits are manually actuated on indications of UF leakage or excessive pressure. The i circui ts may be initiated from the LCR, the ACR, or the airlock on the cell floor near the i compressors. An automatic activation of the HPV occurs when both Pyrotronics System smoke detectors above any one ERP compressor fire or on a first stage compressor high discharge i pr:ssure. A high pressure switch at 7.5 psia alarms the condition while a high-high pressure switch at 10 psia actuates'the HPV. ,

11 Out-leakage Detection System The ERP withdrawal station is monitored with three smoke detection systems which are used to monitor the withdrawal facilities where the operating pressures may exceed atmospheric pressure.

These detection systems are the CADP System, the High Voltage Smoke system, and the Pyrotronics system. The CADP system monitors the compressor and withdrawal areas. This j system performs an alarm (no control) function only. l i The High Voltage Smoke detector system is designed to alarm on UF leakage in the accumulator /

condenser area. Detector heads monitor UF, condenser pipe housing. The microprocessor-based system generates an alarm when UF. leakage is detected. The detector heads in the High Voltage Smoke system are continuously self-tested.

The Pyrotronics smoke detector systems monitor the compressor and withdrawal areas. The compressors and withdrawal stations are monitored by two detector heads over each compressor and two at each withdrawal position. Actuation ofboth detector heads above any one compreswr initiates an alarm and high pressure venting after a two-minute delay. Firing of two detector heads

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NCS A-0326,015.A02  ;

A-2975 A# (8-94)

I NUCLEAR CRITICALITY SAFETY APPROVAL  !

USE RI.KK INK ONI.v -  ;

PART As REQUEST FOR NUCLEAR CRITICALITY SiFETY EVALUATION - Parenoor:9 l 1

1. UvvifMTpt '

I J

at a withdrawal position will cause an alarm, isolation of the cylinder pigtail, and de-energize power to the electric heat tracing. The Pyrotronics system is not self-testing and the detector heads are  ;

tested quarterly. The actual circuitry is tested annually by alarming detectors and verifying  ;

operability of the entire system.

12. Mentilation System

. Exhaust ducts are located over each withdrawal position. These ducts feed into a common exhaust i header. Air is drawn through the exhaust ducts, through the exnaust fan, and is discharged to the l atmosphere at rooflop level. The exhaust fan is turned on during cylinder change operations to expel small quantities of UF. that may escape during the disconnecting of pigtails. The fan capacity is 5,000 cfm, which will perform a complete air change every 2 minutes. A control switch for the j exhaust fan is located outside the withdrawal room so that ventilation can be shut down in the case of a UF. release. The ERP cylinder room ventilation system is automatically shut down if the Pyrotronics' smoke heads in the withdrawal room actuate.

13. Cylinder Chance Oneration Two personnel are present when a cylinder is connected or disconnected using an established 1 procedure and checklist. When cylinders are brought into the ERP Withdrawal Station, they are l first verified to be of the correct size (enrichment restrictions) for the material to be withdrawn. '

Cylinders are then inspected externally for unacceptable damage followed by weighing the cylinder in order to check for water or increased heel mass inside tt.e vessel. Per l ORNUCSD/TM-284,22 Kg of water is needed to achieve a critical configuration for 5%

enriched UO2 F 2 (or 135 Kg of HF for 5% UF.).

Next, a pigtailis attached to the cylinder and the withdrawal manifold. Clean, virgin Teflon gaskets are used in making these connections. A leak check is performed on the pigtail as well as a pressure l

l test. The air-operated pigtail cylinder valve and the cylinder valve itself are checked ft. leakage l through the valve seats by applying nitrogen. The cylinder valve is then opened and the pigtail l pressure is checked to verify clarity. This check verifies that undesirable non-condensibles are not present in the cylinder and that the cylinder is not leaking.

l When a cylinder is to be disconnected, the cylinder valve is closed and the UF,is evacuated from the pigtail. An acceptable leak rate must be obtained to assure that all the liquid UF has been l

removed from the pigtail and to assure that the cylinder valve is properly seated and not leaking.

After the cylinder is disconnected and weighed, a valve protector shield is installed over the cylinder valve. Cylinders are then moved outside on air-operated carts and placed into cradles or on a l railcar by an overhead crane and allowed to cool. In the event that a leaking cylinder valve seat is found after filling the cylinder, the pigtail safety valve is closed and the pigtail purged and .

evacuated. The pigtail is then disconnected at the pigtail safety valve. After the cylinder has l '

cooled, the defective cylinder valve can be safely changed.

.. . . ._ .- . . . - - . ~ . . . _ . , . . . - . - -. - -

l NLSA-0320 Ols.AU2

' - 1 A.2975AS (8-94)

NUCLEAR CRITICALITY SAFETY APPROVAL

. USE RI.ACK INK ONIN.

~

FIRTN REQUEST FOR' NUCLEAR CRITICALITY SAFETY EVALUATION - reseis ris 1 i

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• ,le Valve Closed (Pipe diameters and pressures are approximate) 1 l

\ i (Pipe diamets and presures are approumate)

For Information Only i

Figure 1 - ERP Loop Simplified Process Flow Diagram

. ~ .m ms. _s . ; ..s . ,

A-2975 A0 (8-94) -

NUCLEAR CRITICALITY SAFETY APPROVAL

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Figure 2 - ERP Station Compressors

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A 2975A# (8-94)

\

l NUCLEAR CRITICALITY SAFETY APPROVAL i

- USE RIACK INK ONI Y - {

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PART A:: REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION Fece i3 *rr

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For Information Only Figure 3 - ERP Station Condensers and Accumulators

_ - _ . .- .-. . - , . . - , ._~ - . - .- -. . . - . - - -. ..

I 1

l NCSA-0326_015.A02 j A 2976# (8-94) l NUCLEAR CRITICALITY SAFETY APPROVAL j

. UsE nr. ark INK ovix . ,

PART B NUCLEAR CRITICALITY SAFETY APPROVAL Pace 14 ar19 l Ti!E FISslONABLE MATERIAL oPERAT!oN DESCRIBED IN PART A IS APPAoVED st'IUECT To THE LIMITS AND CONDITIONS PRoVIDED BELOW:

l ERP Withdrawal Station REQUIREMENTS:

• l. The ERP Withdrawal Station shall be limited to a maximum enrichment of 10% "U.

., *2. Enrichment and Fill Limits for cylinders si.all follow Table 1 of this NCSA Part A.

Prior to filling a cylinder, a second verification shall be completed to ensure that the proper cylinder is being used for the enrichinent to be withdrawn. l J

• 3. Both the Gamma Spectrometer System and the Mass Spectrometer System should be operational during withdrawal operations. If either system is out of service, U-tube samples shall be taken at least every eight hours as a redundant means of assuring correct enrichment. If both systems are temporarily out of service, samples shall be taken every 2 !

hours with enrichment results available within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

• 4. The ERP scale pits shall be filled to a minimum depth of 6 inches with Raschig rings. The Raschig rings shall meet the requirements of ANSI Standard 8.5. In the event Raschig rings are removed for service to a scale pit, only the afTected station is required to be removed from sesvice. (The Raschig ring depth of 6" cannot be implemented until the TSR change is approved.)

ORIGINAL l AN YZED BY: (N "$ Engineer) Jason E. Huffer REVIEWED BY: (Nec Enginerr) Russ Dunham

. /1,m [v - Date: April 29.1997 h0V4 ^^ Date: 6 !I!$7 YEVIEWED BY: CS Department Manager)

A.'h  % SW /h Date: 5)l c51 j REVI WED BY: (Saferv .4naksis Departonent Afanager)

REVIE TD BY: (Opera ' g Group) h V Date: hf L sN Date: Slll9 7 APP VED- 1

/ / r/4/47  % 17 h Date ACKNOWt.EDGMENT (Department Afanager): 1 H AVE READ. UNDERSTAND. AND NCSA Number:

AGREE TO THE LIMITS AND CONDITIONS STATED ABoVE. 0326,015. A00 Date:

l l

NCSA-0326,,015.A02 A 2976A# (8-94) i

\

i NUCLEAR CRITICALITY SAFETY APPROVAL  ;

- IfSE Bl.ACK INK ONI,Y - I f PARTB NUCLEAR CRITICALITYSAFE'lY APPROVAL .

l'ese 15 er19 l wo=rwrm - ,

• 5. The scale pits shall be inspected weekly for solution. If found, the solution shall be collected in geometrically favorable containers per NCSA-PLANT 006 or handled per requirement #6.

*6. Prior to discharging the contents of the scale pit to an unfavorable geometry contailer, a )

l representative double sample shall be obtained for analysis. If the lab analysis results indicate )

2 l

a greater than 5'g "U / liter concentration, the contents shall be placed into geometrically favorable containers per NCSA-PLANT 006 or NCSA-PLANT 045.

• 7. The Raschig rings in the scale pits shall be inspected for settling and damage on an annual basis and following any UF6 release leav ng visible uranium in the scale pits. If the rings are l exposed to uranium-bearing materials or any corrosive agent (e.g., acid solutions), they shall  ;

be replaced with certified rings or a representative sample tested and verified that they meet  ;

the requirements of ANSI /ANS-8.5.

l

• 8. The scale pits and equipment housings shall be maintained free of uranium buildup.

Inspections shall be made after any UFg release exceeding 50 grams and when opened for maintenance. Visibly contaminated areas shall be cleaned when found. Housing need only be inspected if the release occurred within the housing. Current known uranium contamination in housings shall be removed when housing covers are removed for j maintenance activities.

• 9. The coolant pressure shall be maintained at least 5 psi above the UF6pressure and at least 5 )

psi above the RCW pressure. l

• 10. The RCW shall be valved off, drained, and the condenser drain valve left open, prior to j draining the R-ll4 coolant system. The RCW shall remain valved off. with the condenser j drain valve left open, until the R-l l4 is returned to the system.

I 1. The ERP System shall be monitored with smoke detection systems for leakage of UF6 at the compressor, withdrawal cylinders, and equipment housings. l

12. An out-leakage detection system shall be in service at the ERP Station with the capability of l

automatic actuation of pigtail isolation initiated the firing of 2 Pyrotronics System smoke

! detectors at a withdrawal position. The system also isolates the cylinder and pigtail when both heads above the withdrawal position fire by shutting the manifold isolation valve. The TSR j

has requirements for a smoke watch when the Pyrotronics System is out of service. Pigtail l isolation can be accomplished manually from outside the withdrawal room.

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i f

NCSA-0326,015 A02

?

j A-2976A#f 8-94)

NUCLEAR CRITICALITY SAFETY APPROVAL  ;

. UsE ni, Ark INK oNix . [

l

~ PART Br NUCLEAR CRITICALITYSAFETY APPROVAL : , Page 16 of19 i

. ammvem -

• 13. The afTected portion of ERP shall be evacuated prior to restan afler the system has been opened to the atmosphere.

. ' ' 14. The maximum UF6pressure at the ERP Stulon shall be 60 psia.

• 15. Prior to withdrawing UF 6into a cylinder, the cylinder shall be visually inspected for damage, ,

weighed and cross-checked against the NMC&A's net weight.

' 1

• l 6. Prior to withdrawing UF,into a cylinder, a cold pressure check shall be performed on the - l

~

cylinder and the cylinder rejected if the pressure is greater than 10 inches of mercury.

• 17. To prevent violating the enrichment limit on cylinders, at least one of the block valves in the cross-tie line between the manifolds of ERP-1 and ERP-2 loops shall be physically locked closed when two different enrichments are being withdrawn into two different size cylinders.

ADMINISTRATIVE AIDS:

18. No temporary or permanent changes shall be made to the physical configuration or operating controls of the ERP Withdrawal Station as described in Pan A and as required by Part B of this NCSA without formal and written approval from the NCS Section

19. The NCS requirements marked with an asterisk (*), except for the requirements relating to the operation and testing of the ERP scale pit sump pumps, shall be included in the applicable sections of the appropriate operating procedures. Requirements may be re-worded in the procedures to improve clarity for use by operating personnel.

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NCSA-0326_,015.A02 ,

l

. 1 NUCLEAR CRITICALITY SAFETY APPROVAL i I

- USE BLACK INK ONLY .

PART C

BASIS. AND DOUBLE C NTINGENCYl CONTROL MATRLY ' rw n ais ERP Withdrawal Station l BASIS FOR NUCI FAR CRITICALITY SAFETY l The nuclear criticality safety of the ERP Withdrawal Station is based primarily on mass, concentration, and moderation control. The ERP Withdrawal Station is used to remove gaseous low-assay UF. product from the cascade, compress and condense the gas to the liquid phase via cooling, and drain the liquid into cylinders. ,

l Enrichment in the ERP Withdrawal Station is limited to a maximum of 10%. A number of administrative

'. controls as well as engineered safeguards and passive barrier., are in place to prevent the loss of control of basic l parameters affecting tiuclear criticality. l j

DOUBI E CONTINGENCY CONTROL MATRIX The following table associates the numbered requirements listed in NCSA Part B with the individual contingency events analyzed in the NCSE. Control A requirements are those requirements which are assumed to fail as the first unlikely or contingent event in each scenario. Requirements listed under Control B are needed to ensure l suberiticality in the event the Control A requirement is lost. In some cases, Controls A or B may contain multiple requirements. If multiple requirements are separated by plus (+) signs, all of the requirements are necessary in order to maintain the control. If multiple requirements are separated by the word "or", then either one of the requirements are sufficient to maintain the control. Requirements for administrative aids in NCSA Pert 3 (e.g. NCS Postings, boundary lines, etc.) are not included in this matrix.

The cascade and ERP structures, systems and components (SSCs) listed below have boundaries as described in the SAR Sections 3.8.2.2 and 3.8.2.3 and quality requirements as described in the Quality Assurance Plan, Appendh A, Section 2.

As notedin SAR Section 5.2.2.3. " Process Evaluation and Approval *: "There are three operations which do not meet the double contingency principle as described earlier in this section. However, these operations have been enluated to be safe, and are discussed in thefollowing paragraphs. These operations are: the handling, storage and transportc. tion oflarge product cylinders: operation ofthe cascade equipment; and handling oflarge cascade equipment items (e.g., compressor, convener, G-17 valve, etc.) which have large deposits ofuranium. "

The double contingency control matrix includes references to certain passive barriers (PB) which are either described or referenced in the NCSA Part A. Rese items, while not specifically listed in the NCSA Part B  !

requirements, are still considered "NCS controls' for the purposes of satisfying the double contingency criteria. l The passive barriers utilized in the double contingency control matrix are detined helew:

ORIGINAL ,

Analyst:Russ Dunham NCSA NO.:

Prepared B : Jason E. Hutfer

1. * '# " 0326 015.A0 4*+

Date: ril 29.1997 ,

Date: Y Ibl ~

NCSA-0326 015 AO' l I

l NUCLEAR CRITICALITY SAFETY APPROVAL

-llSE BLACK INK ONLY -

PART C: BASIS AND DOUBLE CONTINGENCY CONTROL MATRIX rase is or19 j (Cominued) ' ,

i l

PBl: The design of the RCW system and the R-114 coolant system in the ERP Station is such that there l no direct connection between the RCW and the process gas streams. Two separate leakage paths u ou:

I have to develop (RCW to R-114 in the conden-ser and R-114 to process gas stream in the cooler c condenser) in order for there to be a connection.

PB2: The design of the system and cylinders minimize the risk of a major leak of process gas or liquid L7 {

and the inleakage of wet uir.

PB3: The design of the system is of favorabic geometry for 10% "U. l PB4: The scale pits are covered by a steel p; ate. i PB5: Raschig Rings. meeting the reqRements of ANSI R5 -1986. are installed to a minim:A i level of 6" in the scale pits.

UEl: Cylinders are c! caned and conditioned at the X-705 building. Procedural controls are in place at X ~0 i (NCS A-705,_071) which prevent a cylinder from containing water after it has been conditioned l UE2: For 10% ennched UOf:a minimuri of 3 3 Kg. of water is required for a criticality to be possible und, optimum conditions. While the air in the housings would contain some moisture it is unlikely th:

sufficient water will be present.

UE3: If there has been a release at ERP and uranium has entered the pit. it is unlikely that uranium beann solution will be pumped out of the scale pits and into unsafe geometry containers. because of ti response to the original release and the plant off nomial procedures that would deal with such an ever UE4: Accumulation of significant quantitics of uranium in the scale pit due to a release is unlikely because il ,

only openings to the scale pits are small gaps in the steel plates along the rails. A release ofliquid O <

will 11 ash to gas and solid almost immediately and react with moisture in the air. forming UO:F: and H The UOf:will plate out on surfaces throughout the ERP cylinder room. It is unlikely that the majori ;

i of a filled cylinder could find its way into the scale pit and the Raschig rings in the scale pit increase tl amount of ur.vium required to go critical. Thus. it is non-credible that the sufficient uranium cou collect in the scale pits for a criticality to occur due to the steel plates and the Raschig rings.

Note that with six inches ofRaschig rings, over 15000 lbs. ofliquid UF, would need to enter 1 ERP-lA and ERP-2 pus and over !1.000 lbs. ofliquad IIF, would need to enter the ERP-lB pu provsde a mimmum critical depth above the Raschig ring level. Since hytad ilF, cannot exist atmosphericpressure and temperature. hquad ilF, escaping a cyhnder. pigtail or accumulation u J1 ash to a mixture ofapproximately 60% vapor and 40% entrained solid.

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NCSA-0Q015 A02 NUCLEAR CRITICALITY SAFETY APPROVAL USE nLACK INK oNLY-

~PART C: BASIS AND DOUBLE CONTINGENCY CONTROL' MATRIX ras.19 or 9 l < (Caninued)

I l Control A Control B l Contingency Event l (See NCSE) Requirement Physical Requirement Physical ,

Number Control? Number (s) Control? '

A/B. I.a. ] 11+12+PB2 Yes (PB2) 4+5+8+PB1 Yes (PBl&PB5)

+ PB5+UE4 i

A/B. I .b.1 11+PB2 Yes 8+UE2 No l A/B.2.b. I 1+2+3+17 Yr: '17 only) 14+15+16 No  ;

A/B.5.a. I 6 No 5+8+UE3 No .

l  !

l A/B.5.b.1 PB1 Yes 9+10 No A/B.6.a.1 *

• A/B.6.a.2 13 No PB3 Yes A/B.6.a.3 15+UEl No 16 No A/B.6.a.4 PB1 Yes 9+10 No A/B.6 a.5 *

• A/B.6.b.1 5 No 4+7+8+PB5 Yes (PB5)

A/B.6.b 2 PB4 Yes 4+7+8+PB5 Yes (PBS)

A/B.9.1 PB5+4+5+7 Yes 11+12+ Yes (PB2&PBS)

PB2+PB4 I l A/B.9.2 PB5+4 Yes 11+12+ Yes (PB2&PBS) )'

PB2+PB4 l These contingencies have been deemed acceptable by the SAR (see italicized paragraphs on page 17),

l although they do not meet the Double Contingency Principle. The single control protections provided '

for these contingencies are available in the S AR.

l

5 INFORMATION ONLY NCSE-0326 015.E02 Nuclear Criticality Safety Evaluation Page 1 of 19 Part A: Nuclear Criticality Safety Parameters rh rollo-ine parameters t.6ould he addressed:1. Maas.2. Enrichment.

3. Volume. 4. Geometry,5. Concentration, Density,6. Moderation. 7. Interaction. H. Renection,9. Neurrnn A bsorption, and 10. Other. For each parameter, indicate its applicability to the ns ionable material operation being analyzed and the method of control utilized on the parameter etc if appropriate,in Section A. In Sectinn B. identify anticipated events (extemal and intemal), normal and credible abnormal opecuting ennditions that may affect thegaremeter (i.e. contingencient Number the enntingenries. j ERP WITIIDRAWAL STATION l A.1 Mass - CONTROLLED The following pieces of equipment in the ERP are mass controlled:

. i a Scale Pits I a Equipment Housings l

)

A.I.a Large UF cylinders an. filled directly above the scale pits at the withdrawal station.  !

Large quantities of uranium could therefore accumulate in the scale pit if a massive release occurred. The scale pits at two of the withdrawal positions (ERP-1 A and i ERP-2) are approximately 12-feet by 8.5-feet. ERP-1 A has a maximum depth of 73 l inches and ERP-2 has a maximum depth of 51 inches. The scale pit for the third 1 withdrawal position (ERP-1B) is approximately iI feet 2 inches by 6.25-feet, with a maximum depth of 47.5 inches. The scale pits are filled to a depth of 6 inches with i Raschig rings. j l

Contingencies:

A.I.a.! Accumulation of UO F, in the scale pit at a cylinder fill station.

A. I.b Some of the equipment and process gas lines are enclosed in housings to ensure that the process gas is maintained at a minimum temperature of 165"F. At temperatures below 134*F, process gas at atmospheric pressure conditions condenses to a solid deposit. There are a number ofindividual housing units in the ERP station including the process gas compressor housings, the condenser and ERP-1 accumulator housings, the pipe gallery housing, the housing surrounding the process pipelines connecting the accumulators to the discharge manifolds and the discharge manifold housings. The ERP-2 accumulator is insulated by glass wool contained within a 13-inch 1.D. aluminum outer sheath. In the event of a UFoleak inside one of the condensed process gas housings or in the accumulator sheath, UF 6 could collect into a large mass. Under normal operating conditions, no uranium is present in the housing outside of process piping / components.

Analyst: ' <>on E. Huffer Peer Reviewer: NCSE NO.:

%f x._. m$  % W -0333 O G Gr ,

te: May 8 ;997 Date: 5/3/97 i/6#

s

NCSE-0326_015.E02 1

I Part A: Nuclear Criticality Safety Parameters (continued)

Page __2._ of I8 ,

A catastrophic leak of liquid UF. inventory from accumulators, condensers, or other large components was considered. A massive release of this nature would require total collapse of the structumi supports followed by loss of containment and was judged to be a non-credible event.

Contingencies: _

A.I.b.1 Small/ slow leakage of 7F. into an equipment housing.

A.2 Enrichment - CONTROLLED The entire ERP Withdrawal Station is enrichment controlled.

A.2.a Enrichment is controlled for the withdrawal station as a consequence of process conditions established for the total cascade. Enrichment is limited at ERP to a maximum of 10% 2 "U. A loss of enrichment control (greater than 10%) at ERP would require an upset condition throughout the entire cascade and isjudged to be a non-credible event.

Contingencies: None A.2.b Vadous size cylinders are present on-si:e for use at ERP which have different assay limits. It is possible that the wrong cylinder can be used and its allowable enrichment (see table 1 in NCSA Part A) will be exceeded.

The maximum sized cylinders used for the withdrawal of UF is 14 tons. As shown in Reference 6, an enrichment of at least 12.7%2 "U would be required to go critical in a 10-ton cylinder under moderation control. 14-ton cylinders have the same diameter but are longer. 2%-ton cylinders have a radius less than that of 10-ton and 14-ton cylinders. POEF-T-3597 shows that a single 2%-ton cylinder is suberitical up to an enrichment of 19% "U. Since all cylinders are 611ed under 2

2 moderation control, they need to be 511ed with uranium enriched above 10% "U for a criticality to occur.

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NCSE-0326_015.E02 i

Part A: Nuclear Criticality Safety Parameters (continued)

Page ~3 of M ,

l l- l i

l A ' nuclear criticality is not possible if a single cylinder is filled with the wrong ,

enrichment, since all cylinders used at ERP require enrichment above 10% for .

L criticality or a loss of moderation control. It was shown that greater than 10%

l ' enrichment is a non-credible event (see A.2.a). Addition of moderator is covered j i . in A.6.a.4. However, several cylinders filled with a higher than allowed l - enrichment has not been analyzed and could pose a criticality concern. .

1:  ;

Contingencies:  ;

A.2.b.1 A cylinder is filled with a higher than allowed enrichment. }

A.3. Volume - NOT CONTROLLED i

Contingencies: None ,

i .

l A.4. Geometry - CONTROLLED The following pieces of equipment in the ERP are geometrically controlled: l a Condensers e Accumulators ,

a Piping A4a The ERP station condensers, accumulators, and piping are all 8-inch diameter or less.  ;

)

It is not a credible event to defonn the equipment to the extent where criticality would )1 be possible. Two reasons for this are that the system is designed to handle the normal J

operating pressures (less than 60 psia), and to reach pressures significantly above this pressure would require a severe operational upset and is not considered credible.

Secondly, the equipment that could see higher pressure is geometrically controlled and is cylindrical, which would rupture before any significant deformation occurred.

in addition, unapproved physical modifications to equipment by plant personnelis a j potential contingency and was considered. However the equipment listed above with identified dimensions are part of the design basis for this NCSA and therefore j modifications were not considered a credible contingency l-Contingencies: None l

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NCSE-0326_015.E02 )

l Part A: Nuclear Criticality Safety Parameters (continued)

Page 4 of 18 l

' A.S. Concentration / Density - CONTROLLED The following pieces of equipment in ERP are concentration or density controlled: ,

a Coolant System Any other means for the introduction of fissile material into the equipment or systems other '

I than the contingencies listed below are not considered credible.

A.S.a in the event of a UF release; scale pits are sampled to determine if there is signi0 cant uranium contamination in the rings.

Contingencies: '

A.S.a.1 Failure to sample the scale pit and await results prior to transferring the solution into unfavorable geometry containers.

A.5.b The Coolant System is of unfavorable geometry nnd under normal operating  ;

conditions contains no uranium.

l Contingencies: J A.S.b.I Process gas enters the coolant system.

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• NCSE-0326_015.E02 1 i

Part A: Nuclear Criticalit'y Safety Parameters (continued) l l-Page 5 of 18 A.6. Moderation - CONTROLLED

[ The following pieces of equipment in ERP are moderation controlled: l t

e Entire ERP system containing UF. (from compressors through cylinders)  :

a Scale pit The presence of moderation in ERP system is controlled through the engineered physical l design of the UF 6system, lubrication oil system, gas coolers, Coolant System, and RCW  :

supply; as well as by engineered alarms and control systems. Loss of moderation control l

l introduces moderator to the UF. as well a; presents the possibility for UF to undergo a  :

chemical reaction to form ane'her uranium compound with different reactivity properties. l Moderator, for example, can be present as wet air inleakage to the PG stream or nearby l as liquid water in the RCW supply to the R-114 coolant condenser. The addition of lube  ;

l oil to the system is highly unlikely due to the design of the compressor seal system This )

i event would require a complete failure of a seal coupled with a failure of operations to )

notice. ,

in the event ofinleakage of moist air into the system. UF would hydrolyze to form dry deposits of UO32 F in the process equipment. Some deposits may build up and the equipment may need to be removed from the ERP system. Criticality safety of equipment removed for

. maintenance is covered in NCSA PLANT _062 " Cascade Maintenance" . Criticality safety of equipment that is classified as "PEH" is evaluated in NCSA-PLANT 028. Since UO2 F, is hygroscopic, H2O can be absorbed, thereby moderating deposits. For this reason, plant dry air buffers are used to preclude entry of wet air. The air plants are operated at a dew point I

of approximately -60 F.

I Moderation control is maintained if the H/U atom ratio does not exceed 0.088 in the liquid l l

. phase. Based on an analysis by John Barber (Reference 7), the minimum pressure required l

to condense UF. containing greater than 0.081 mole fraction HF (H/U ratio greater than 0.088) requires the UF. pressure in the condenser to exceed 60 psia. The normal operational' L UF pressure from the second stage compressors is approximately 35 psia and is limited by procedure to a maximum of 60 psia.

Before the condenser pressure could reach 60 psia, the back pressure on the first stage s compressor would rise. A high pressure switch on the first stage compressor, set at 7.5 psia, alarms the high discharge pressure, while a high-high pressure switch set at 10 psia actuates l the HPV.

l

. NCSE-0326_015.E02 l Part A: Nuclear Criticality Safety Parameters (continued) t Page 6 of 18 ,

t When the HPV circuitry is actuated,- the compression loop automati: ally vents back to the  !

vent retum header, the flow control valves to the condenser close. the condenser vent valve - l closes, the air-operated manifold isolation valve on the cylinder pigtail closes, and the station suction valve closes. Thus the cylinder being filled (the only component of unfavorable -  !

geometry) would be isolated from the condenser / accumulators. A failure of the HPV system,  ;

allowing the withdrawal cylinder to continue to fill, would be necessary to lose moderation control.  !

i A.6.a Under normal operating conditions the UF stream 6 is under moderation control. l Contingencies: ,

l A.6.a.1 Addition of moderator to the system due to inleakage of wet air into l the process gas stream. ,

A.6.a.2 Addition of moderator to the system due to failure to evacuate the l l

appropriate sections of the system prior to restart.  ;

A.6.a.3 Presence of a moderator in the withdrawal cylinder to be filled. j A.6.a.4 Addition of moderator to the system due to inleakage of coolant  ;

i containing water. .

.l' A.6.a.5 Addition of moderator to the system due to failure of the compressor bearing and seal causing lube oil inleakage.

A.6.b Under normal operating condition',s little or no water is present in the scale pits.

No other moderators are present in the scale pits.

Contingencies:

A.6.b.1 Slow accumulation of water in a scale pit. j A.6.b.2 Fast accumulation of water in the scale pit due to sprinkler system i activation. )

i  !

t I

t 1

NCSE-0326_015.E02 Part A: Nuclear Criticality Safety Parameters (continued) f Page 7 of 18 l

P A.7. Interaction - CONTROLLED -

The following pieces of equipment in ERP are interaction controlled: '

- a Condensers

-m Accumulators ,

a Piping A.7.a Process equipment relationships are fixed during ERP Station operation.- The  ;

condensers, accumulators, an' d nearly all system piping is enclosed in housings. No credible scenarios were found for displacing these piems of equipment.

The filled withdrawal cylinder is mobile but limited in movement because the cart  ;

^

on which it moves is on rails thus preventing the cylinder from coming in close proximity to other ERP station fissile material.

Contingencies: None A.8. Reflection - NOT CONTROLLED Contingencies: None A.9. Neutron Absorption - CONTROLLED Borosilicate glass Raschig rings are used in the scale pits ' while the chemical and physical i tests and maintenance practices for such rings as specified in ANSI standards have not been j implemented, the NCS Section (5.2) of the Certification Application SAR, commits to the following regarding Raschig rings:

"For Borosilicate glass Raschig rings, the rings are used in environments where they would normally be exposed to water only. Inspections are made of the rings for settling and damage on an annual basis. If a UF leak exceeding 50 grams should occur, exposing the rings to a corrosive environment, the rings would be replaced with certified rings, or the rings would be tested and verified acceptable according to the testing requirements of ANSI /ANS-8.5."

(Ref. 8)

Per standard Portsmouth NCS policy, it is acceptable to take credit for neutron absorption i at the scale pit since the Raschig rings are not exposed to visible amounts of uranium.

j The scale pits are filled to at least 6 inches of Borosilicate glass Raschig rings. A release of '

UF.at one of the withdrawal stations may result in the accumulation of UF in the scale pit.

NCSE-0326_,015.E02 L

j Part A: Nuclear Criticality Safety Parameters (continued)

Page 8 of IE l l

I i i

The ERP-IB scale pit also contains 6 inches ofBorosilicate glass Raschig rings, at this time, l ewn though it is currently notfimctioning. However, long term plansfor the ERP-2 scale l pit is to install water level alarms and an automatically activated sump pump; allowing  ;

removal ofthe Raschig rings. A new evaluation will be requiredat that time.

The Boron-10 content of Raschig rings is depleted as the Boron absorbs neutrons. The Boron-10 depletion mte is low enough to be considered negligible given only background i.

neutron radiation levels. The only identified means of accelerated Boron-10 depletion is due to a release of UF.at a withdrawal station with subsequent deposition of the uranium in the scale pit or exposure of the rings to a corrosive agent (e.g., acid solution) that could leach out the Boron-10. If such a relm.e occurs, operating procedures require that the Raschig rings be replaced with new rings meeting ANSI Standard 8.5 or tested per tH same standard.

Even if the Raschig rings were not present, both a loss of mass control and a loss of moderator control would be required for criticality to occur.

Note that the OSR and TSR describe all of the scale pits in the ERP station to be filled with i I

12" of Raschig Rings. This evaluation has shown that 6" of Raschig Rings is sufficient to provide nuclear criticality safety in the scale pits in the event of a UF. release. In addition, the part A of the request specifically allows more flexibility of operation, allowing stations to be taken out of service and have the rings removed, without effecting operation of the unaffected stations. This flexibility is not addressed in current version the OSR or TSR.

Raschig rings contribute to the effectiveness of 'ke mass and moderatiun controls by increasing the quantities of uranium mass and moderation that would have to reach the pits for a criticality to occur, thereby making such accumulation clearly non-credible given the NCS controls imposed and process conditions present.

Since mass control is based on prevention of a UF. release as described in the accident analysis, which concludes that the only credible scenario that could result in the large release of UF above the scale pits with potential accumulation of UO:F, in the scale pits is a pigtail rupture (SAR Section 4.2.3.2). The scenario assumes that some liquid UF would reach the scale pits due to the rapid vaporization of the UF . Once UF6is exposed to the atmosphere approximately 60% goes to vapor and 40% to small particulate solid (snow-like) that will diffuse over the ERP area and the steel plate that covers the scale pit. Even ifit was possible for all of the 127.5 pounds of UF./UO2F2 to enter the scale pits the resultant depth would be 0.03 inches which is considerable 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 Raschig rings.

Moderation control is based on '% unlikeliness for any significant quantities of water or other moderators 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

. . . . - . . - . - ~ _ . . - - - - . - . - . - . . - . - . - - - . - - - - - . . . _

i f

l. NCSE-0326_015.E02 4

' A.3550# (9-18.%) i 1

Part A: Nuclear Criticality Safety Parameters (continued)

Page 9 of t !t t

E

- the scale pits also inhibits the flow of any water into the scale pits. The NCSA concluded that  ;

there were no credible accidents in which there would be a simultaneous release of enouch ~

~

I

uranium and water to the scale pits to result in a criticality with a 6 inch Raschig ring depth.

The Raschig ring depth of six inches is adeque.te to assure that even a liquid cylinder passive  !

failure, a very unlikely event due to quality and testing required of UF cylinders, would not ,

add enough uranium (over 15,000 lbs would be required for pits l A and 2) to the pit to cause ,

a criticality. i t

A.9.1 The Raschig rings are not present in the scale pit at the time of an l accidental release ol' uranium, a large amount of which enters the scale l L pit.' l l'  !

A.9.2 The Raschig rings' Boron 10 content is depleted at the time of an accidental .i l

release of uraninm into the scale pit.  !

A.10. Other - NONE l

i r

l l

-. -.- ._.- .-. - --. .- .- .- . - . . -- - . ~ . _--

i

(

NCSE-0326 015.E02

• Part B: Contingency Analysis (For each contingency provide the justification that the tissionable material ,

operation remains subcritical. Identify the contingency b.:ing addresseJ by number.

Page 10 of 1lL F

ERP WITIIDRAWAL STATION t

! B.1 Loss of Mass Control B.I.a.1 Accumulation of UO 2F2in the scale pit at a cylinder fill station (

The following controls are in place to prevent uranium buildup in the scale pit:

m The UF. leak is detected and alarmed by the Pyrotronics smoke detection l ,

l system. The system isolated the affected withdrawal position in the event  !

L of such a leak.

m After a UF, release estimated to exceed 50 grams, the scale pit is checked for uranium contamination.

e The scale pit is covered by a steel plate.

In addition to the above controls which prevent a uranium buildup in the scale pit, moderation is also required for criticality to occur.

The scale pit is covered with steel floor plates. The only openings are small gaps in the plates along the rails. It is not possible that the majority of a filled cylinder could find its way into the scale pit. Liquid UF6 cannot exist at atmospheric temperatures and pressures; upon release form a cylinder, pigtail or accumulation, the UF6 will flash to a mixture of 60% vapor and 40% small paniculate solid (snow like) and be widely dispersed over the ERP withdrawal station. The Raschig rings in the' scale pit increases the amount of uranium required to go 3 critical. Thus, it is unlikely that the sufficient uranium coula collect in the scale pits for a criticality to occur due to the steel plates and the Raschig rings; six inches of Raschig rings would be required,i.e., over 15,000 lbs. ofliquid UF.in the ERP-1 A and ERP-2 pits and over 11,000 lbs. in ERP-1B pit.

No credible accidents were identified which would resalt in the simultaneous release of uranium and addition of moderator to the scale pit. The pits are checked weekly for water.

and the sumps pumped if water is found; several hundred gallons of water would be required to fill the pits to a depth of 6 inches.

Since both inoderation and mass of uranium buildup is required for criticality, double l

contingency is met.

Analyst: J son E. Huffer Peer Reviewer: NCSE NO.: 1 M y 4 3 uwMd v- 0326 015.E y Date: May 8.1997 Date: bD ~

l #'

NCSE-0326 015.E02 Part B: Contingency Analysis (For each contingency provide the justi6 cation that the 6ssionable matenal operation remains suberitical. Identify the contingency being addressed by number.

Page 11 of 18 B.I.b.1 Smail/ slow leakage of UF. into an equipment housing.

Leaks would only occur at flanges, valves, and x-joints in the housings in which the equipment or piping is above atmospheric pressure. The leak would be detected and alarmed by the smoke detection system in each of the housings. Immediate action would be taken'to isolate the leak. The

- equipment housing will be cleaned in the event of a leak as necessary.

Also, note that for 10% enriched UO2 F: a minimum of 13 Kg. of water is required for a criticality to be possibh ander optimum conditions. While the air in tne housing would contain some moisture, it is unlikely that suflicient moderator would be present.

Therefore double contingency is met.

B.2 Loss of Enrichment Control B.2.b.1 A cylinder is filled with a higher than allowed enrichment.

The diffusion process is very well known and the enrichment per stage in the cascade is very predictable. The cascade is limited to 10% 2 "U. Withdrawal of material from the cascade exceeding this limit is a non-credible event that would require a total upset condition in the cascade.

Filllimits on large cylinders that can be filled at ERP are listed in Table 1 of the NCSA Part A.

Mass spectrometers and gamma spectrometers are used to monitor the assay of :he UF that enters the cylinders. The mass spectrometers automatically traps analyzes, and recorus the assay every 5 to 6 minutes. Each hour, an operator records the current assay on the withdrawal data sheet.

A gamma spectrometer monitors the flow with probes on the liquid line before it enters the withdrawal manifold. The gamma spectrometer records the assay and is connected to a high assay alarm which, when activated will close the cylinder fill block valve.

Both the, Gamma Spec system and the Mass Spec system should be operational during withdrawa:

operations. If either system is out of service, U-tube samples are taken at least every eight hours as a redundant means of assuring correct assay. If both systems are temporarily out of service.

l l

samples are taken every 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> with assay results available within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

i The maximum sized cylinders used for the withdrawal of UF is 14 tons. As shown in Referenct 6, an enrichment of at least 12.7%2 "U would be required to go critical in a 10-ton cylinder unde moderation control.14-ton cylinders have the same diameter but are longer, since the model wa

( infinite in length the 14 ton cylinders would also be conservative to the model. 2%-ton cylinder l

have a radius less than that of 10-ton and 14-ton cylinders. POEF-T-3597 shows that a singl 2%-ton cylinder is subcritical up to an enrichment of 19% "U. Since all cylinders are fille, 2

under moderation control, a single cylinder would need to be filled with uranium enriched abov 10%2 "li to have the notential to achieve a critical contipuration.

i NCSE-0326_015.E02  ;

i  ; -

l' Part B: Contingency Analysis (For each contingency provide the justification that the tissionable material f operation remains subcritical. Identify the contingency being addressed by number.

Page _n_ of 18 l

l In order to prevent cross over between the headers, the doubl' e block valves in the cross-tie line between the manifolds of the A and B loops are physically locked closed when two different assays are being withdrawn into two different size cylinders.

l The first controlis on the enrichment of the uranium entering the cylinder being filled. This is done ,

j with administration requirements of the enrichment allowed in cylinders and the operation l requirement that the cascade only produce 10% enrichment material. In addition real time l measurements of the enrichment of the material are taken.

The second control is on moderation in both the ERP system and the cylinder being filled. The l maximum UF pressure allowed in the ERP system is 60 psia so that gaseous HF will not go into the UF6 solution. The cylinder is also inspect:d for damage and the cylinder weight is check. against the NMC&As net weight to ensure that water has not entered the cylinder. (Note: for 10% enriched UO 2F,,10 Kg. of water or 22 pounds is required for a criticality to be possible ) Additionally, a  ;

vacuum test is preformed on the cylinder to remove any HF that may have been generated by any 1 water that entered a cylinder potentially containing a heel.  !

I Therefore the double contingency principle is met. l l 1 l B.5. Loss of concentration / density control B.S.a.1 Failure to sample the stale pit and await results prior to transferring the solution into unfavorable geometry containers.

Trus contingency would be caused by an operator error. In order for this contingency to result in a criticality, the following must occur:

1) A large source of fissile material must enter the scale pit.

l- 2) A source of water must enter the scale pit and dissolve the fissile materialinto solution.

3) The combination of "'U and water must be such that the solution is greater than 5 3 "'U/ liter.

4) The operator fails to sample the solution and wait for the results before transferring the solution.

i to an unsafe geometry container. .

)

Since at this point of the scenario otT-normal procedures would be in etTect and it would be unlikely for the administrative requirements on sampling to be violated.

, Therefore the double contingency principle is satisfied.

I

NCSE-0326 015.E02 Part B: Contingency Analysis (For each contingency provide the justification that the tissionable material operation remains subcritical. Identify the contingency being addressed by number.

Page __ D _ of I8 B.S.b.1 Process gas enters coolant system.

The concentration / density of UF. in the coolant system is controlled by the physical barriers between the two systems as well as by controlling the R-114 pressure at least 5 psi above the UF pressure in order for the UF to contact and be moderated by RCW, the failure of 2 physical barriers must occur, namely 1) failure of the barrier between the RCW loop at the R-114 condenser and 2) failure of the barrier between the process gas and the R-114 at the gas cooler or condenser.

The R-ll4 coolant pressure is maintained at least 5 psi above the UF, pressure to prevent UF, from entering the Coolant System in the event ofleakage through the process gas coolers or condensers.

and at least 5 psi above the RCW oressure to prevent water from entering the R-il4 system A pressure switch actuates an ala: 1 and closes the RCW valve when the pressure differential between j the process gas and the coolant drops below 5 psi. A pressure switch actuates an alarm and closes  :

the RCW supply valve on either a high RCW pressure or a low Coolant pressure. During shutdown for maintenance, the RCW side of the coolant system is valved off, drained, and the valve l letl open, prior to draining the R-l 14. The UF. is evacuated prior to removing the R-l14. {

i A nuclear criticality due to loss of concentration / density control of UF in the coolant systems would )

! involve the concurrent failures of 1) the RCW/coolar,t/PG stream coolers / condensers and 2) the I

( controls (physical and administrative) which ensure that R-114 is always at a higher pressure than the l UF or the RCW.

l

! Therefore, the double contingency principle is met l 1

B.6. Loss of moderation control B.6.a.1 Addition of moderator to the system due to inleakage of wet .iir into the process gas stream.

Wet-air inleakage through expansionjoints, flanges, compressor seals, welds, etc. could result in the formation and accumulation of solid uranium compounds in the process gas system. A large portion of the ERP station (ponions downstream of the second stage of compression)is above atmospheric pressure and would not have wet air inteakage.

Several process systems provide an indication or alert that wet air inleakage or loss of moderation control may be taking place. The monitoring and control panels for the buffer systems provide a means ofidentifying failures in compressor flanges, compressor discharge flanges, valve bonnets and bellows, and double wall expansion joints. Alarms are provided both locally and in the ACR Inleakage at expansionjoints and some valves would result in a butter gas low pressure alarm and a buffer gas high flow alarm Additional indicators of solid buildup in the process side of the ERP station are a compressor motor load alarm, compressor surge and a high pressure alarm on the firs-

l I

i NCSE-0326 015.E02 l

Part B: Contingency Analysis (For each contingancy provide the justification that the tissionable material l

l operation remains subcritical. Identify the contingency being addressed by number. )

Page 14 of 18 j l l For wet air inleakage between the first stage and second staj;e of compression, high first stage i discharge pressure would be the indicator. The ERP Station HPV circuits are manually actuated on indications of excessive pressure. The circuits may be initiated manually from the LCR, the ACR, l or the airlock on the cell floor near the compressors. An automatic activation of the HPV occurs on I a first stage compressor high discharge pressure. A high pressure switch at 7.5 psia alarms the )

condition while a high-high pressure switch at 10 psia actuates the HPV. For inteakage upstream of ,

the first stage of compression, motor load and compressor surge are the likely indicators.

. Failure to isolate the ERP station and stop th ialeakage of wet air is therefore contingent on a failure of the automatic activation of the HPV on the high-high compressor discharge alarm and failure of the' operator to manually activ2te the HPV given the automatic isolation was unsuccessful. However, there are currently no other controls outside of random factors (such as l the rate of reaction of UF with water) that can be applied in the case of wet air inleakage.

l Double contingency cannot be demonstrated.

B.6.a.2 Addition of moderator to the system due to failure to evacuate system prior to restart, Prior to restart of the ERP Station, UF6 must flow through the system to verify the proper enrichment prior to starting withdrawal. If moderator is present in the system. the potential exists for a mass of moderated uranium to form inside the process piping and equipment.

! Failure to evacuate the appropriate sections af the ERP system prior to use would require failure to follow procedures by operations.

In addition, if water was present in the system, the components which can hold a significant amount of water (accumulators, piping, etc.) with the exception of the cylinder are of favorable geometry for 10% enrichment. If water was present in the system, as UF. was introduced, the water and UF.would react to form UO F and HF. UO 2F would plate out on the interior of the 2 2 equipment and would not flow into the cylinder. If a significant amount of water is present in the system, the HF being generated would cause a higher pressure in the accumulator and condenser, with a corresponding higher back pressure on the first stage compressor. This pressure increase would be alarmed when the pressure reached 7.5 psia. ,

i Therefore the double contingency principle is satisfied.

1 I

l

l ~

1 l l NCSE-03:'6 015.E02 l I

Part B: Contingency Analysis (For each conungency provide the justification that the tissionable material l l operation remains suberitical. Identify the contingency being addressed by number. I

! Page 16 of _.l.L_ j i

B.6.a.5 Addition of moderator to the system due to failure of the compressor bearing  ;

and seal causing tube oil inleakage. J It is remotely possible for inleaking oil to pass through the seal along the compressor shaft into the process compressor and the UF. system. The oil reacts with the UF6forming a moderated mass of 1 uranium. Oil is unlikely to enter the compressor due to the seal design. This design requires multiple j failures before oil could enter the compressor. Single seal failures can lead to UF6entering the seal '

exhaust system. The Seal-Exhaust System is covered separately in building specific NCSAs. There

. is also the possibility of the oil inleakage to a pipe and not the compressor, then a significant blockage would be required for operations to detect the deposit. I Criticality due to oil leaking into the cascade is considered to be unlikely due to seal design.  !

operational indicators of oil inleakage and routine inspections however, double contmgency cannot i 1

be shown.

1 l

l B.6.b.I Slow accumulation of water in a scale pit.

The scale pits are inspected weekly for solution. In addition to the prevention of water buildup in the I scale pit, loss of mass control (uranium in the scale pit) is also required for criticality to occur. The i scale pit is checked for uranium after any release of UF. exceeding 50 grams. If found in greater than trace amounts it is cleaned up.

The first control is controlling the amou;.t ofliquid that can collect in the pit. The scale pits and l reservoir tanks are checked weekly for sclution.

l The second control is on the collection of mass and the presence of Raschig rings. In addition.

following any release greater than 50 grams, visibly contaminated areas are cleaned up. No credible accidents were identified which would result simultaneously in both a release of uranium and addition l of moderator to the scale pit. Since both moderation and uranium buildup are required for criticality, double contingency is met.

B.6.b.2 Fast accumulation of water in the scale pit due to sprinkler activation.

I j The activation of the sprinkler system would be detected by operations statT via alarming of the i sprinkler fire system. While a water buildup in the scale pit could occur. loss of mass control (uranium in the scale pit) is also required for criticality to occur. The scale pit is checked for uranium quantities after any release of UF6exceeding 50 grams. If found in greater than trace amounts it is cleaned up.

The first controlls controlling the amount ofiiquid that can collect in the pit There are metal plates j covenng the pit which will slow the collection of water in the sump down.

i

_, .. _.___.-.____.,m _, . _ - . _ _ _ - . - . _ _ _ _ _ _ _ . _ _ - ~ _ . _ _ . - _ _ .

NCSE-0326_015.E02 A 3550# (9-18-96) _

Part B: . Contingency Analysis (For each contingency provide the justification that the 6ssionable inaterial '

l operation reinains subcritical. Identify the contingency being addressed by number.

Page f7 of f8 1

The first controlis controlling the amount ofliquid that can collect in the pit. There are metal plates  !

covering the pit which will slow the collection of water in the sump down. l 1

The second control is on the collection of mass and the presence of Raschig rings. Following any release greater than 50 grams, any visibly contaminated areas of the scale pit are cleaned up. No '

credible accidents were identified which would result in both a release of uranium to a scale pit and

. activation of the sprinkler system. Since both moderation and uranium buildup are required for l criticality, double contingency is met.

B.9 Neutron Absorption 3

B.9.1 The Raschig rings are not present in the scale pit at the time of an accidental release of uranium, a large amount of which enters the scale pit.

The absence of Raschig rings in the scale pit would involve 1) failure to follow NCS requirements .

for maintaining Raschig rings meeting ANSI S.5 standards at a minimum depth of 6 inches inside the i scale pit and 2) failure to conduct the annual and weekly visual checks of the pit which would reveal the error. '

I Even if the Raschig rings were not present, both a loss of mass control and a loss of moderator l l

l control would be required for a criticality to occur. l Therefore, the double continency requirement is met.

B.9.2 The Raschig rings' Boron-10 content is depleted at the time of an accidental release of  ;

uranium into the scale pit.  ;

l i

The Boron-10 content of Raschig rings is depleted as the Boron absorbs neutrons. The Boron-10

. depletion rate is low enough to be considered negligible given only background neutron radiation "

" gMe,vels. The only identified means of accelerated Boron-10 depletion is due to a release o '

-withdrawstation with subsequent deposition of the uranium in the scale pit or exposure of the rings

. l to a corrosive agent (e.g., acid solution) that could leach out of the Boron-10. If such a release  ;

l occurs, operating procedures require that the Raschig rings be replaced with new rings meeting ANSI

fE '

. f/1/f 7 Standard 8.5 or tested per the same standard.

Even if the Boron-10 content of the Raschig rings was depleted, both a loss of mass control and a !

l loss of moderator control would be required for criticality to occur.

Therefore, the double contingency requirement is met.

t NCSE-0326 015.E02 _=

l l

Part B: Contingency Analysis (For each contingency provide the justification that the fissionable material f operation remains suberitical. Identify the contingency being addressed by number. .

Page 16 of 18  !

L l

l

References:

2

1. Paxton, H.C. and NL Pruvost, " Critical Dimensions of Systems Containing "U, "'Pu, and "'U,' !

LA-10860-MS (1986 Revision), Los Alamos National Laboratory, Issued July 1987. {

2. Jordan, W.C. and J.C. Turner, " Estimated Critical Conditions for UO 2Ff Hp Systems in Fully Water-Reflected Spherical Geometry," ORNUTM-12292, Oak Ridge National Laboratory, Issued j l December 1992.

3. GAT-225, Revision 4, " Nuclear Criticality Safety Guide for the Portsmouth Gaseous Diffusion l i

Plant", March 15,1981.

4. ANSI /ANS-8.1-1989,"American National ::ndard for Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors," Revision of ANSI N 16.11-1975, American Nuclear Society,1988.

5. Carter, R.D.; Kiel, G.D. and K.R. Ridgway, Criticality Handbook, ARH-600, Atlantic Richfield i Hanford Company, June 28,1968.

I

6. Tayloe, et al.," Nuclear Criticality Safety Analysis for increased Enrichment Limit in 10-ton (48X) !

UF Cylinders," POEF-T-3563, May 1991 j

7. Barber, John et al.,"The HF-UF Phase Equilibria and the Selection of Operating Conditions for UF. i Withdrawal and Storage Systems in Low-Enrichment Gaseous DitTusion Cascades," K/ETO-95 Interim Edition. March 1993

8. D'Aquila, D., "NCS Requirements for Survei!!rce and festing of Raschig Rings.'

POEF-520-95-138, October 12,1995 l

l

November 15,1996 NCSA-0330_007.A00 j f ':

A-2975# (8-94) ) ' " " * ' ' #I NUCLEAR CRITICALITY SAFETY APPROVAL

- USE BIACK INK ONLY -

WWMiW;fMtM@l%%%;t#D2a#%;MMW..n-mwmt,nu.kaWWM uma.J%..,aM%34x,l . g% >

!PhkT AHREODESTFOR NUCLEAR'CRITICAftTY SXFETY EVXLUATrotrs ,

a TITLE:

Tails Withdrawal Station BUILDINo: oPERATINo AREA: DURATION: WORK REQ. #

X-330 Tails Station Permanent N/A CRITICA1JIY ALARM COVERAGE- (X ) YES ( )NO F1SSIONABLE MATERIAL DESCRIPTION NUC11DE (U-233. U 235, PU-239, ea:.) MASS: FISSloNABLE NUCUDE PERCENT:

, l U-235 Not Limited Maximum 5%

FORM ANDCOMPOSrnoN: UF, - gaseous, liquid, and solid SIHPPINo. TRANSFER. AND PORTABLE CONTAINERS:

2.5.10. and 14 ton cylinders l REFERENCE PREV 1oUS NCS APPROVAL:

REFERENCES:

OAT /ODP-1073 NCSA-330 003 FCA486 NCSA-PldNT004 OAT.DM-884 Rev.2 OAT /ODP-1074 NCSA.PIAKr016 O AT-DM.961 Rev. 2 ORNUCSOr!M 284 j OM . CA 6.6 Rev. I NCJE-0JJc? Co2rn I

XP44X)CA2302 (OM -CN 9.5)

XP44X)CA2392(oM CN 9.5.1) 5 l

XP4COCA2395 (oM CN 9.5.2)

XP440CA2303 PA AfTnm e n nn~.

DESCRIPTION OF THE FISSIONABLE .MATEI @@@ TION:vv" n s nutLcu Wf. T The Tails Withdrawal Station is designed to remove gaseous depleted UF, from the cascade, compress the gas, condense the gas to a liquid state via cooling, and drain the liquid into cylinders. These cylinders are allowed to cool on railcars in the Tails withdrawal cooling yard causing the UF, to solidify, and are then moved to a storage area. In addition to the withdrawal  !

l of depleted UF., the Tails Withdraw station is designed to permit the simultaneous withdrawal of product UF, at one or two of the withdrawal positions. UF, weighted average assays in the range of1 to 5% are withdrawn at the Tails Station when it is operating in the product withdrawal mode. When withdrawing Tails material withdrawal is normally limited to an enrichment less j than 0.95%2 "U.

i i

UF, cylinder fill weight and the maximum weighted averaged enrichmenu for cylinders shall be less than or equal to the values given in Table 1 prior to removal or the cylinder from the scale cart.

Tills IS LelLY A REQUEST. Ti(E LIMITS AND CONDITIONS IN PART B ~

MUST BE READ. UNDERSTOOD. ACKNOWLEDGED. AND IMPLEMENTED.

RE D BY: c:- REQUEST APPROVED DY: REQUEST DAT m V pp/d& v il{M 96

l November 15, 1996 NCSA-0330_007.A00 A-2975A# (9-20-%)

NUCLEAR CRITICALITY SAFETY APPROVAL

- USE BLACK INK ONLY -

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Standard Fill Weight Lhnit and Maximum Weighted-Averalfe Enrichments for Cylinders Used at the Tails Assay Withdrawal Station Serial Description Maximum Weighted Cylinder Number Fill Limit Average L Model Enrichment  :

(Pounds)

' Limitation (%)t l N/A 2%-ton 4,950 5.0 30n (concave)

N/A 2%-ton 5,020 5.0 30B (convex) 10-ton (heavy 21,030 4.5 48A N/A '

wall) 20,700 1.0 48B(T) -

10-ton (thin wall) 10-ton (heavy 21,030 4.5 i 48X 1 TO 5000 wall) 14-ton-(heavy 27,030 4.5

<  : 48F 9231 TO 9660 wall) 14-ton (heavy 27,560 4.5 48Y 9661 TO 9999 wall) 1TO 14-ton (thin 26,070 48GtOM) 111820 wall wi skirt) 4.5(1.0) i11821 & 28,000 ABOVE 150001- 14-ton (thin 27,030 4.5(1.0) 48G(HX) 151000 wall w/ skirt) 151001- 14-ton (thin 27,030 4.5(1.0) 48G(H) 15xxxx wall) t Enrichments in parenthesis are the limits given in USEC-651 for shipping. .

NCSA-0330 007.A00 November 15, 1996 A 2975A# (9 20-96)

NUCLEAR CRITICALITY SAFETY APPROVAL

- USE BIACW INK ONIN -

IIENNYdId5N$NdNIYbbdEN$$ffdALtTY5IEtiO1i$iAYidd$d!$w$ihin mxamasawmwwwmmmmepmwe < ' + m w w m.munawuma awar w The Tails station is located on the ground floor of the northeast section of X-330. A' mezzanine level above this ground floor space contains the accums 'ators, valving, condensers, and piping supporting the Tails withdrawal station. The second floor contains the compressors, piping, and valving that interfaces the withdrawal station with the cascade. .

The systems and equipment associated with the Tails Withdrawal Station are described below. The major system components are described first, and then support systems for those components are described.

- The arrangement of components in the Tails Withdrawal System is illustrated in figure 1. ,

I. Comorrupn ,

1 All Tails withdrawal compressors are of centrifugal design. An Allis-Chalmers AC-38 compressor normally provides the first stage of compression for Tails withdrawal, with a second AC-38 compressor available as backup. The first stage of compression increases the pressure of the flow to approximately 6.5 to 7.5 psia. The gas is then cooled. The Coolant system is described in Section 5.

The second stage of compression is supplied by one or two Worthington compressors depending on l the withdrawal rate. Normally, both Worthingtons operate, with one loop cperating in recycle if not needed to meet the target withdrawal rate. The second stage of compression increases the pressure of the flovi to approximately 30 to 38 psia. An Allis-Chalmers AC-12 compressor and a third Worthington compressor are present, which can be used for first or second stage compression, as required.

Each stage ofcompression has a recycle loop to adjust the system pressures based on the flow rate to the condenser. The compressors include alarms on several out-of-tolerance conditions associated directly with the compressors or with the Tails system withdrawal loop. Compressor trips are provided for low lube oil pressure, overcurrent, and undervoltage.

Double-walled expansion joints are located on the suction and/or discharge lines of the compressors.

The space between the expansion joint bellows is buffered and connected to the buffer monitoring l

panel to provide immediate detection of expansion joint single-wall failure. The Buffer Gas System j is described in Section 7.

The first stage AC-38 compressors and the AC-12 are lubricated by one of two building unit lubricating oil systems, one of which serves as a backup. The Worthington cornpressors have two independent lube oil systems. One system services 30-WB-1 and 30-WB-2, and another service 30-WB-3. The tube oil systems are described in Section 6.

l

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9 NCSA-0330_007.A00 November 15, 1996 A-2975A# (9-20-%)

NUCLEAR CRITICALITY SAFETY APPROVAL

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l The Tails withdrawal compressors are located inside a housing on the second floor. Thermostatically controlled electric and steam heaters are used to control the heat in the com' pressor housing. .

When performing dual withdrawals at Tails (i.e., both Tails and product withc'rnval), multiple compressor configurations are possible. Typically, one AC-38 compressor and one Worthington compressor would be used for each withdrawal stream. In the event of a compressor failure, the Allis-Chaltners AC-12 compressor can be used as the first or second stage compressor. The spare

- Worthington corhpressor(30 , 1 i), would typically only be used as a second stage compressor, but

- can be used as a first stage e ...ssor if necessary.

LCondensers and Accumulators After second-stage compression, the UF 6 i. cooled to a liquid state in a condenser. Three condensers are present, one for Tails withdrawal, cae for product withdrawal, and one as a backup in the event j of a failure of either of the other two condensers. The flow rates to the condensers are controlled by  ;

flow control valves. The process gas i.; cooled from approximately 350*F to approximately 150*F and condensed. The process gas condensers are cylindrical and have an inside diameter of 10-inches.

Each of the condensers has 76 monel tubes, 5/8" O.D., which will contain the liquid UF6 . Double j block valves are present for isolating the backup condenser from the operating process.  !

The nuclear criticality safety of equipment and operations handling liquid UF. is- based on moderation co_ntrol which limits the H/U ratio to 0.088. This is done by limiting the pressure in i the condensers to less than 60 psia which ensures that the H/U ratio is 50.088. Noncondensible i 1

gases are vented from the condenser to the vent header via a pressure control valve.

Three accumulators are present in the Tails system. Accumulator number 2 which is used as the Tails accumulat , has an inside diameter of 30 inches, and has a volume of approximately 13,300 lbs of  !

UF,. Accumulators I and 3 may be used as product accumulators and normally are run in parallel.

Each of these accumulators has an inside diameter of 10 inches and have a capacity of approximately 2900 lbs of UF..

The discharge of the Tails condenser passes directly to the withdrawal ma. .ifold. The dinharge of the two product accumulators are joined and pass through an isolation valve to the withdmwal manifold. The isolation valve automatially closes if a gamma spectrometer detects an assay outside t

of the limits of target assay. This valve may aisa be closed manually at the discretion of the operator.

l The gamma spectrometer is used only during product withdrawal, and is described in Section 9.

i ~he condensers and accumulators are located in heated housings, as are the lower liquid distribution ,

headers. These housings are heated with steam that is controlled thermostatically.

s __ _ _ _. _. _ ._ __ _ . _ _ . . _ _ .

November 15, 1996 t

NCSA-0330_007.A00 A-2975A#(9 20 96) l NUCLEAR CRITICALITY SAFETY APPROVAL

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3. Withdrawal M nifolds -

l There are four withdrawal positions associated with the Tails station. All of the positions may be used j l tor tails withdrawal. The first two positions are restricted to Tails withdrawal (less than .95% "U).

2 I The third position is sometimes used to withdraw product when sufficient capscity is not available at the other withdrawal facilities. The fourth position is normally assigned to the Uranium Material l

Handling Depanment to weigh cylinders, although it could also be utilized for withdrawal. Double l

block valves are present for isolating the tail withdrawal positions (#1 & #2) from the product

- withdrawal positions (#3 & #4).

l Each withdnwal manifold is equipped with several manual operated valves:

1) A block valve to allow the liquid UF, to flow into the cylinder.  ;

l 2) Evacuation valves to remove UF, from the pigtail or to provide evacuation for any part of the l withdrawal lona. l l 3) Nitrogen purge valve.

l 4) Double Block Cross Tie Valves.

l The cylinder being filled is connected to the fill manifold via a pigtail. This pigtail is electrically heat traced to prevent freeze out of the UF,in the pigtail. The cylinder valve is also electrically heated via a valve cap heater.

Each cylinder pigtail can be isolated by two air-operated valves in the case of 3 mpture. The cylinder

! safu> valve (air-to close) is attached to the cylinder valve while ths manifold block valve (air-to-open)is attached to the withdrawal manifold. If the two UF, detectcrs at a withdrawal station alarm, the control circuit will close the two valves at that station and turn off power to the heat tracing. l A compressM air reservoir is present in the system to ensure that compressed air is available to close l the cylinder safety valve in the event of a loss of plant air.

1

4. Withdrawal Positions Cylinders being filled are mounted on air-operated carts. Compressed air is supplied to the air-operated cart through a hose. A scale is provided at each withdrawal position. Digital readouts are provided for positions 1,2, and 3 at the scale. During the filling operation, the cylinder weight is '

' monitoree. .st least once every hour to ensure that the cylinder is not overfilling.

The withdrawal station is protected by a wet pipe fire sprinkler system.

4 Each withdrawal position has its own scale pit. These four scale pits are approximately 12-feet by l 8.5-feet, with a depth of 4.25-feet. The scale pits are filled to a depth of at least 6 inches with Raschig l rings and are inspected weekly for solution. If solution :: found, it is analyzed for uranium l concentration and enrichment.

l l

^ '

NCSA-0330_007.A00 Novembeg- 15, 1996 A-2975 A# (9-20-96)

NUCLEAR CRITICALITY SAFETi APPROVAL

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The following scale pit modifications relevant to nuclear criticality' safety are planned per POEF-831-96-1036:

1. Scale pit s' umps will be installed. The sumps will be 8 inches in diameter and 8 inch deep. ,

l

2. An integral automatic level control sump pump will be installed in each sump. The pump discharge lines will tie into a common discharge line and flow into a new reservoir tank.

3. Flow switches will be installed in the discharge lines which will give a visual and audible alarm

. in the adjacen*. room. )

- 4. Moisture detectors will be installed in the sumps with a audible and visual alarm in the adjacent room.

5. A new reservoir tank will be installed which will consist of a U shaped tank constmeted of 8 inch diameter PVC pipe with 10 foot legs.

Following the completion of these modifications, the NCS section will be notified. l

5. Coolant System The process gas stream is cooled after the first stage of compression. After second-stage compression, the UF,is cooled to a liquid state in a condenser. Both the gas cooler and the UF, condenser are served by a nonevaporative coolant system, which is in turn cooled by recirculating cooling water l (RCW). The coolant used in-this system is trichloroheptaflurobutane (C-437/816). A schematic of l 1

the Coolant System is shown in Figure 2.

The coolant is circulated through the loop by a centrifugal pump, with a second pump provih s an installed spare. The coolant flows through the UF, coolers and condensers and then to a ' utant cooler before being ' returned to the pump suction. If necessary, the Tails Coolant System can be  !

drained to a 42-inch O.D. drain tank. l i

A valve on the RCW maintains the coolant at 150' to 170*F to ensure that the UF condenses to the liquid phase and not the solid phase. A steam admission path is provided for the Coolant cooler to allow initial heating of the coolant if the loop has been shut down long enough for the coolant l

temperature to drop below 150*F.

The coolant pressure is maintained at least 5 psi above the UF. pressure te prevent UF from entering the coolant system in the event of a leak, and at least 5 rsi above the .lCW pressure to likewise j

prevent water from entering the coolant system in the event of a leak. The Coolant pumps are maintained with a discharge pressure of 70-80 psig and are checked once per shift for proper pressure. ,

If enriched uranium is being withdrawn, the Coolant is sampled once per month for water and dried if Ge water content exceeds 50 ppm.

l l

NCSA-0330 007.A00 November 15, 1996 l

A 2975A# (9-20-%) _

1 L NUCLEAR CRITICALITY SAFETY APPROVAL

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6. Lube Oil System C Lubricating oilis supplied to the AC-38 and AC-12 compressors by one of two unit lubricating oil systems, one of which serves as a backup. Lubrication for the Worthington compressors is supplied by an independent oil system having two oil supply pumps, one on operation and one on (auto) ,

standby. Oil is pumped from an unfavorable geometry reservoir, through an oil cooler, to the compressor and motor bearings. An alarm and compressor motor trip will occur on a low oil pressure, ,

and an alarm will occur on a high lube oil temperature from a compressor bearing. Refer to l

- NCSA-PLANT 054 " Lube Oil".

7. Buffer Gas Systems The monitoring and control panels for the buffer systems provide a means ofidentifying failures in compressor tlanges, compressor discharge flanges, valve bonnets and bellows, r.nd double wall expansion joints. Alarms are actuated when a component failure occurs.

The buffer gas is supplied at two pressures because of the large pressure range across the compression and condensation system. The high pressure buffer panel provides gas at 25 psig to all components after the second stage of UF, compression and a low pressure panel supplies gas at 10 psig to the other l components. The G-17 valves in the high pressure system also cannot withstand the full range o pressure that might be seen with a single source of buffer gas. Instrumentation switches the buffe on these valves from 10 to 25 psig when necessary.

8. Seal System The seal system provides dry, clean air and nitrogen to the compressor seals. In the event of a seal failure, a seal exhaust high or low differential pressure alarm will sound in the ACR. The seal exhaust is provided by the Area 2 Seal Exhaust System. See NCSA-0330_005 for NCS controls on seal exhaust.

9. Assav Momtorine Eauinment The *U assay (enrichment) of the product withdrawal is monitored with mass and gamma l spectrometers. The Tails side only has a mass spectrometer. The mass spectrometers (two both withdrawalloops. The mass spectrometer automatically traps process gas from the dischage the first stage compressor cooler discharge, analyzes the gas, and records the assay every five minutes. Each hour, an op-rmor records the current assay on the withdrawal data sheet.

The gamma spectromei -itors the flow to the product withdrawal manifold with probes on the l

liquid line upstream a ' ,4nifold. A gamma spectrometer is present only on the proauct withdrawal manifold loo n .i is only used when performing product withdrawals. The assay is recorded on terminals in the ACR at 5 to 6 minute intervals. If the assay exceeds the predetermine assay set point for a cylinder size, the air-operated valve located between the accumulator anu u

NCSA-0330,,007.A00 November 15, 1996 A.2975A# (9 20 96)

NUCLEAR CRITICALITY SAFETY APPROVAL

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withdrawal manifold is signaled to close. The maximum permitted assay for the product withdrawal side ofTails (#1 and #3 accumulators) is 5%. Due to an internal algorithm, ihe gamma spectrometer will not respond until the actual assay value is +0.05 above the setpoint value. U-tube samples are also taken at least every eight hours (12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for Tails withdrawal) as a redundant additional means ofdetennining 2"U assay.

If the gamma spectrometer is out of service during pJoduct withdrawal. laboratory samples are j

collected every two hours and the mass spectrometer is monitored at 1/2 hour intervals. If the mass l

. spectrometeris out ofservice (gamma spectrometer operating) during product withdrawal. laboratory

• samples are collected every two hours. If both the mass and gamma spectrometers are out of service ,

during product withdrawal, gas samples are collected and analyzed every two hours with assay results l l

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

l

10. Hich Pressure Ventine (HPV)- Manual Only i

The Tails station has high pressure venting (HPV) to relieve the system pressure in case of emergency. l If the HPV circuitry is actuated, the two air-operated valves on the cylinder pigtail close; power to the l electric heat tracing is de-energized; the Wonhington suction, discharge, and recycle valves close; and i i

the Wonhington compressors trip. The HPV circuits are manually actuated on indications of UF, leakage or excessive pressure. The circuits may be initiated from the ACR, or the airlock on the cell floor near the compressors.

j

. . l

11. Outleakaee Detection System j

The Tails Withdrawal station is monitored with three smoke detection systems which are used to l

monitor the ponions of the withdrawal facilities where the operating pressures may exceed l

atmospheric pressure. These detection systems are the CADP System, the High Voltage Smoke ;

l system, and the Pyrotronics system. The CAL 'vstem monitors the compressor and withdrawal areas. This system performs an alarm (no contro., function only. The detector heads in the CADP system are continuously self-testing.

l The High Voltage Smoke system is designed to alarm on UF, leakage in the accumulater/ condenser area. Two detector heads are placed in each UF, condenser companment and four detector heads are located in each pipe housing going to the condensers. The microprocessor-based system generates

! an alarm when UF, leakage is detected. The detector heads in the High Voltage Smoke system are continuously self-tested.

l fhe _.

I The Pyrotronics smoke detector systems monitor the compressor and withdrawal areas, compressors and withdrawal stations are monitored by detector heads over each compressor withdrawal position. Actuation of both detector heads above any one compressor initiates an alarm >

Firing of two detector heads at a withdrawal position will cause an alarm and isolation of the cy l

pigtail. The Pyrotronics system is not self-testing and the detector heads are tested quarter actual circuitry is tested annually by alarming detectors and verifying operability of the entire system.

NCSA-0330_007.A00 November 15, 1996 A-2975A# (9-20-%)

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12. Ventilation System ,

Exhaust ducts are located over each withdrawal position. These ducts feed into a common exhaust header. Air is drawn through the exhaust ducts, through the exhaust fan, and is discharged to the atmosphere at"rooflop level. The exhaust fan is turned on during cylinder change operations to expel small quantities of UF that mre escape during the disconnecting of pigtails. The fan capacity is 20,000 cfm, which will perform a complete air change of the withdrawal room every 5 minutes.

Control switches for the exhaust fan are located iiside and outside the withdrawal room so that ventilation can be shut down in the case of a UF release. The sentilation system is automatically shut down when the gas release alarm syste has been actuated.

.13. Cylinder Channe Ooeration Two operating personnel are present when a cylinder is connected or disconnected, and they are required to complete an established procedure and checklist.

When cylinders are brought into the Tails Station, they are first verified to be of the correct size (enrichment restrictions) for the material to be withdrawn. Cylinders are then inspected externally for unacceptable damage followed by weighing the cylinder in order to check for water or increased heel mass inside the vessel. Per ORNilCSD/TM-284, 22 Kg (48.4 pounds) of water

-is needed to-achieve a critical configuration for 5% enriched UO 2 2F (or 135 Kg of HF for 5%

UF).

Next, a pigtail is attached to the cylinder and the withdrawal manifold. Clean, virgin Teflon gaskets are used in making these connections. A leak check is performed on the pigtail as well at a pressure test. The air-operated pigtail cylinder valve and the cylinder valve itself are checked for leakage through the valve seats by applying nitrogen. The cylinder vdve is then opened and the pigtail pressure is checked to verify clarity. This check vrifies that undesirable non-condensibles are not present in the cylinder and that the cylinder is not leaking.

When a cylinder is to be disconnected, the cylinder valve is closed and the UF. is evacuated from the pigtait An acceptable leak rate must be obtained to assure that all the liquid UF. has been remnved from the pigtail and that to assure that the cylinder valve is properly seated and not leaking. After the cylinder is disconnected and weighed, a valve protector shield is installed over the cylinder valve.

Cylinders are then moved outside on air-operated carts and placed into cradles or on railcars by the overhead crane and allowed to cool.

In the event that a leaking cylinder valve is found after filling the cylinder, the cylinder safety valve is closed and the pigtail purged and evacuated. The pigtail is then disconnected at the cylinder safety l valve. After the cylinder has cooled, the defective cylinder valve can be safely changed.

NCSA-0330_007.A00 Noveritber 15, 1996 A-2975A# (8 94) l NUCLEAR CRITICALITY SAFETY APPROVAL

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ll ij N f f ;. h. . ~~ ;"] November 15,1996 NCSA-0330_007.A00

-... . - .; 1 A-2976# (8-94)

NUCLEAR CRITICALITY SAFETY APPROVAL

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PART Di h'UdLEAR CiUTICALIN SAFETY APPR$MM ' Pmlior17-TiiE FISSloNABLE MATERIAL OPERATION DESCRIBED IN PART A IS APPROVED SUBJECr TO TijE LIMITS AND CONDIT!oNS PROVIDED BELoW:

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Tails Withdrawal ,_

c REQUIREhENTS , [ QL

• l. The Tails Withdrawal Station shall be limited to a maximum enrichment of % "U 2

1. '/'F

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• 2. Material in the 30" Tails Accumulator portion of the Tails Withdrawal Station shall be 23:

- limited to a maximum enrichment of 0.95% U.

• 3. Enrichment and Fill Limits forgijngrs shall follow Table 1 of this NCSA Part A.

Prior to filling a cylinder, an in caen_ent verification shall be completed to ensure that the proper cylinder is being used for the enrichment to be withdrawn.

• 4. Both the Gamma Spec System and the Mass Spec System should be operational during product withdrawal operations. If either system is out of service, U-tube samples shall be taken at least every eight hours as a redundant means of assuring correct enrichment. If both systems are temporah out of service, samples shall be taken every 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> with enrichment results available within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

^

• 5. To p? event violating the enrichment limit on cylinders, the double block valves in the cross-tie line between the liquid manifolds of the tails and product loops shall be physically locked closed when two different enrichments are being withdrawn into two ,

different size cylinders.

l ANALYZED BY: (NCS Engineer) REVIEWED BY: (NCSE grneer/

Date ll N b 'rm Date // 5 'il l8 i REVlEWED UY: CS )e truent Manager) {

f/n/Clf, 0 (s b Date. b REVIEWED B (Operatmg Group) REVlf D BY: (Safety A nalysss Department Managers SW Date: I l$ $ ., Date llhf9h I'RO E j Y \ Daoe lb) ,

ACK wl.lilxiMEN r (Deparsment Manager > I IIAVE kliAD. IlNDERSTAND A ND NCSA Numte Atilt E Tu ll)E l .lMITS ANH C(INI)l rl()NS ST A I EI) Alk )VE 74 % thae ] * ]

aw.- 313DJ

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^

NCSA-0330_007.A00 November 15,1996 A.2976A# (9-20-%) _

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'6. The Coolant pressure shall be maintained at least 5 psi above the UF, pressure and at least l

5 psi above the RCW pressure.

• 7. The RCW shall be valved off, drained, and the RCW drain valve left open, prior to draining the Coolant from the system. The RCW shall remain valved off and the RCW l

drain valve left open, until the Coolant is returned to the system.

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• 8. If enriched uranium (above .95% "'U) is being withdrawn, the Coolant shall be sampled at l 1

l least once per month for water.

• 9. If the water content of the Coolant exceeds 50 ppm (see # 8 above), the Coolant is sampled t'or uranium. If the uranium concentration indicates greater than 350 grams "5U within the Coolant system, NCS is immediately notified. If the water content exceeds 50 ppm, but less l than 350 grams "'U is present, the Coolant shall be dried.

l

• 10. The scale pits shall be filled to a minimum depth of 6 inches with Raschig rings. The l

j Raschig rings shall meet the requirements of ANSUANS Standard 8.5. l i

• 11. The scale pits shall be inspected weekly for rolution. If found, the solution shall be sampled l

for uranium concentration and enrichment and removed. If the analysis results indicate a greater than 5 g "'U / liter concentration, the contents shall be placed into geometrically favorable containers per NCSA-PLANT 025 ar NCSA-PLANT 045.

• 12. The Raschig rings in the scale pits shall be inspected for settling and damage on an annual l

l hasis and following any UF, release exceeding 50 grams. If the rings are exposed to uranium-bearing materials or any corrosive agent (e.g., acid solutions), they shall be replaced with certified rings or tested and verified that they meet the requirements of ANSUANS  !

Standard 8.5.

• 13. The scale pits and equipment housings shall be maintained free of uranium buildup.

l Inspections shall be made after any UF release exceeding 50 grams and when opened for maintenance. Visibly contaminated areas shall be cleaned when found. Housing need only l be inspected if the release occurred within the housing. Current known uranium l contamination in housings shall be removed when housing covers are removed for maintenance activities.

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NCSA-0330_007.A00 November 15,1996 A.2976A# (9-20-96)

NUCLEAR CRITICALITY SAFETY APPROVAL

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14.a The Tails Withdrawal System shall be monitored with smoke detection systems for I leakage of UF. at the compressor, withdrawal cylinders, and equipment housings. l An out-leakage detection system shall be installed at theNStation with the capab 1

14.b manual and automatic actuation initiated either by the firing of 2 Pyrotronics System smoke j detectors at a compressor position or withdrawal position. The system shall isolate the cylinder.

• 15. Prior to withdrawing UF 6into a cylinder, the cylinder shall be visually inspected for damage, weighed and cross-checked against the NMC&A's net weight.

• 16. Prior to withdrawing UF, into a cylinder, a cold pressure check shall be performed on the cylinder and the cylinder rejected if the prssure is greater than 10 inches of mercury.

• 17. The affected portion ofTails shall be evacuated prior to restart of the system after the system has been opened to the atmosphere.

• 18. The maximum UF. pressure at Tails shall be 60 psia.

ADMINISTRATIVE AIDS:

19. No temporary or permanent changes shall be made to the physical configuration or operating controls of the Tails Withdrawal Station as described in Part A ano as required i by Part D of this NCSA without formal and written approval from the NCS Section.

20. The NCS requirements marked with an asterisk (*) shall be included in the applicable sections of the appropriate operating methods. Requirements may be re-worded in the procedures to improve clarity for use by operating personnel.

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NCSA-0330_007.A00 November 15,1996 NUCLEAR CRITICALITY SAFETY APPROVAL

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un a . n ..,.~.w asa w um wwu na n ,llMATRIR CONTRO m ,e . -n Tails WithPawal Station BASIS FOR NUCLEAR CRITICALITY SAFETY t .

He nuclear criticality safety of the Tails Withdrawal Station is based primarily on mass, concentration, and moderation control. The Tails Station is used to remove gaseous low-assay UF, product from the cascade, compress and condense the gas to the liquid phase via cooling, and drain the liquid into cylinders.

Enrichment in the Tails Station is limited to a maximum of 5%. A number of administrative controls as

- well as enginced safeguards and passive barriers are n place to prevent the loss of control of basic parameters l affecting nuclear criticality.

l f DOUBLE CONTINGENCY CONTROL MATRIX l

l The following table associates the numbered equirements listed in NCSA Part B with the individual I contingency events analyzed in the NCSE. Control A requirements are those requirements which are assumed to fail as the first unlikely or contingent event in each scenario. Requirements listed under Contro!

f , .

B are needed to ensure suberiticality in the event the Control A requirement is lost. In some cases, l

Controls A or B may contain multiple requirements. If multiple requirements are separated by plus (+)

signs, a!! of the requirements are necessary in order to maintain the control. If multiple requirements are separated by the word "or", then either one of the requirements are sufficient to maintain the control.

1 Requirements for administrative aids in NCSA Part B (e.g. NCS Postings, boundary lines, etc.) are not jncluded in this matrix.

The cascade and Tails structures, systems and components (SSCs) listed below have boundaries as described in the SAR Sections 3.8.2.2 and 3.8.2.3 and quality requirements as described in the Quality Assurance Plan, Appendix A, Section 2.

As noted in SAR Section 5.2.2.3, " Process Evaluation and Approval": *There are three operations which do r'ot meet the double contingency principle as described earlier in this section. However, these operations have been evaluated to be safe, and are discussed in thefollowing paragraphs. These operations are: the handling, storage and transportation oflarge product cylinders, operation of the cascade equipment; and handling oflarge cascade equipment items (e.g., compressor, converter, G-17 valve, etc.) which have large deposits of uranium. "

ne double contingency control matrix includes references to certain passive barriers (PB) which are either described or referenced in the NCSA Part A. These items, while not specifically listed in the NCSA Part B requirements, are still considered "NCS controls" for the purposes of satisfying the double contingency

criteria. He passive barriers utilized in the double contingency control matrix are defined below:

Prepared By: Analyst: NCSA No.:

l L- p Date:I '2//,4 / 7 f; / ap"h Date:

0330,007.A00 4

NCSA-0230_007.A00 Novambar 15,1996 l

i NUCLEAR CRITICALITY SAFETY APPROVAL

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In sorne of the contingency events listed in the double contingency control matrix, mferences are madc to independent and unlikely events or conditions which must occure concurrently with the losee o: l another control in order for a criticality to be possible. The unlikely events (UE) which appear in the matrix are defined below, i

PBl: The design of the RCW system and the Coolant system in the Tails Wit is such that there is no direct connectian between the RCW and the process gas streams /

Two separate leakage paths would have to deve!op (RCW to coolant in the conder:ser anc coolant to process gas stream in the cooler or condenser) in order for there to be r l

! connection.

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PB2: The design of the system and cylinders minimize the risk of a major leak of process g liquid UF. and the inleakage of wet air.

PB3: The design of the Tails Withdrawal System and cylinders (filled under mo l i l are of favorable geometry for 5% 23'U. l l

PB4: The scale pits are covered by a steel plate.

UEl: It is unlikely that both a steam leak and UF release occure at the same time.

UE2: Cylinders are cleaned and conditioned at the X-705 building. Procedural controls are it place at X-705 (NCSA-705_071) which prevent a cylinder from containing water after it been conditioned.

UE3: For 5% enriched UO 2F2a minimum of 22 Kg of water is required for a criticality to b, 4

possible under optimum conditions. While the air in the housings would contain som moisture it is unlikely that sufficient water will be present.

Note 1: The only openings to the scale pits are small gaps in the steel plates along the rails. <

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release ofliquid UF, will fiash to gas almost immediately and react with moisture in the l

forming UO22F and HF. The UO2F2 will plate out on surfaces throughout the ERP cylind room. It is unlikely that the majority of a filled cylinder could find its way into th and the Raschig rings in the scale pit increase the amount of uranium required to go i

Thus, it is unlikely that the suflicient uranium could collect in the scale pits for a criti '

to occur due to the steel plates and the Raschig rings.

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l Tails Withdrawal Station Control A Control B Contingency Event Physical Requirement Physical Requirement (See NCSE) Control?

Number Control? Number (s)

A/B. I.a. I 14+PB2 Yes 10+ 11 + 13 +PB4 Yes (PB4)

(See Notel) 1

( Yes 13 +UE3 No A/B. I.b.1 14a + PB2 PB1 Yes (6+7) or (8+9) No l A/B. I .c.1  !

l 2 No 18+PB3 Yes (PB3) i .

A/B.2.b.1 A/B.2.c.1 1+3+4+5 *M* U 15 + 16+ 18 No / e 16 PB1 Yes (6+7) or (8+9) No A/B.5.a.1 11 No 13 No A/B.S.b.1

• i A/BI6.a.1 l

17 No 1+PB3 Yes (PB3)

A/B.6.a.2 No 16 No A/B.6.a.3 15+UE2 Yes No A/B.6.a.4 PB1 (6+7) or (8+9)

A/B.6.a.5 No 10+ 12 + 13 No A/B.6.b.1 11 10 + 12 + 13 No A/B.6.b.2 11 + PB4 Yes (PB4)

!' 13+UEl No A/B.6.c.1 14 Yes (14)

• These contingencies have been deemed acceptable by the SAR (see italicized paragraphs on 15), although they do not meet the Double Contingency Principle. The single control provided for these coatingencies are available in the SAR.

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3 L eweT37h5{ 1;S n .s : NCSA-0333 Ol7. A00 October 11.1996

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LA-2975# (2-16-96)

NUCLEAR CRITICALITY SAFETY APPROVAL USE BLACK INK ONLY-PART A: REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION Pace 1 or 22 UTLE:

Low Assay Withdrawal (LAW) Station BUILDLNG: OPERATING AP.EA: DURATION: WORK REQ. a X-333 LAW Station Perrnanent N/A CRmCALTTY AIARM COVERAGE: ( X ) YES I nNO

• FISSIONABLE MATERIAL DESCRIlmON NUCLIDE (U-233. U-235. Pu-239. etc.) MASS: FISSION ABLE NUCLIDE PERCENT:

U-235 Not Limited Maxunum 109c FORM AND COMPOSmON: UF. - caseous liquid and solid .

SHIPPING. rRANSFER. AND PORTABLE CONTAINERS:

/2wc4, 2%.10. and 14 ton evitnders l

REFERENCES:

REFERENCE PREVIOUS NCS APPROVAL:

G ATJGDP.1073 NCSA PLANTo25 FCA 523C2, FCA-616. FCA-286Cl FCA-423. FCA-G AT'GDP 1074 NCSA PLANTC36 430

. GAT DM 738 Rev. I NCsA PLANT 054 1 OM CA 5.6 Rev. 4 NCSA 0705 072 XP4-CO CA2360 (OM - CA 6.5 Rev. 2) NCS A-0333'Ol

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6 XP4-CO.CA2365 DOM CA 6.5.2 Rev. I NCSE-0333,01",58 ORN!JCSDrnt-284 4% */V/M POEF 8?l-96-1036 XP4-CO-CA2365 (OM CA 6.5.4 Rev. 0) g ' l V XP4-CO-CA2303 (oM - CA 6.5.6 Rev 1)

XPX CO-CA2312 (OM - CA 6 5.7 Rev. 0) i p

~ i .I XPX-C A-CO2302 (OM - CA 6 6 Rev.1) i CONTROLLED copv INSCR!l'flON oF TiiE FISSIONABLE MATERIAL OPERATIOS: - - .

I The low-assay withdrawal (LAW) station is designed to remove gaseous low-assay UF.

product from the cascade, compress the gas. condense the gas to a liquid state via cooling.

i and drain the liquid into cylinders. These cylinders are moved to the LAW cooling yard and l allowed to cool causing the UF. to solidify. They are then moved from the LAW cooling l yard station to a storage area. The system is designed to permit the simultaneous withdrawal l of UF of two different assays into cylinders of any approved size. While the LAW station 235 j is limited to 10% U in itself, it is typically run at lower assays due to production l

requirements. Under normal operating conditions, UF assays in the range of 1 to 4.95 % are withdrawn at the LAW station.

UF,, cylinder fill weight prior to removal of the cylinder from the scale cart and the maximum weighted averaged enrichments for cylinders shall be less than or equal to the values given in Table 1.

11115 IS oNLY A *,EQUEST. Tile LIMITS AND CONDITIONS IN PART B MUsT BE READ. UND""tTOOD. ACKNOWLEDGED. AND IMPLEMENTED.

REQUEs1TD BY- - REr UEST APPR VFD BY: REQUES r DATE:

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NCSA-0333_017.A00 November 19, 1996 A 2975 A# (2-16-96) w NUCLEAR CRITICALITY SAFETY APPROVAL USE BLACK INK ONLY -

TIN 5 j raseiet22 PART A:[REDUEST FOR' NUCLEAR CRITICALITY SAFETY EVAL y: -

Table 1 Standard Fill Weight Limit and Maximum Weighted-Average Enrichments for Cylinders Used at the Low Assay Withdrawal Station

, Cylinder Serial Description Maximum Weighted

. Model Number Fill Limit Average 1 (Pounds) Enrichment Limitation (%)t 30A N/A 2 %-ton 4,950 5.0 (concave) 30B N/A 2%-ton 5,020 5.0

. (convex) ,

(

48A N/A 10-ton (heavy 21,030 4.5 wall)  ;

l 48B(T) -

10-ton (thin 20,700 1.0 w41) l 48X* 1 TO 5000 10-ton (heavy 21,030 5.0(4.5) l wall) i 48F 9231 TO 14-ton (heavy 27,030 4.5 l 9660 wall) 48Y 9661 TO 14-ton (heavy 27,560 4.5 9999 wall) l 1 TO 14-ton (thin 26,070 48G(OM) '

111820 wall w/ skirt) 4.5(l .0) 111821 & 28,000 ABOVE 150001- 14-ton (thin 27,030 4.5(1.0; 48GalX) 151000 wall w/ skirt) 151001- 14-ton (thin 27,030 4.5(1.0) 48G(H) 15xxxx wall) t Enrichments in parenthesis are the limits given in USEC-651 for shipping.

• Specially marked 48X cylinders are allowed to a maximum 5% enrichment.

NOTE: If UF is to be wnhdrawn with an average enrichment greater than 5% "5U, a

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j . 'A-2975 A# (2-16-96> -

NUCLEAR CRITICALITY SAFETY APPROVAL  !

- USE BLACK IW ONLY-PART A: REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION Page 3 of C

'ONTINt 4 th The LAW station is located on the ground door of the west-center section of X-333. A mezzanine level above.this ground floor space contains accumulators, valving, condensers, and piping supporting the withdrawal operation. The second door contains the compressors that interface with the cascade and draw the process gas into the condensing system. The process gas is liquefied via cooling and is drained from the accumulator into cylinders on the ground door. 1 There are two identical loops of equipment (A-Loop and B-Loop), each supporting two of the four i withdrawal positions at the LAW station. Figure 1 illustrates a simplified flow diagram for the A-Loop of the LAW station.

Each loop of the LAW station can be supplied by various auxiliary service headers. Each loop rjpically consists of an Allis-Chalmers AC 12-5 compressor, a cooler, a Worthington compressor. ,

, a condenser, two accumulators, and a withdrawal header. The low-assay product is withdrawn from the cascade as a gas, compressed in two compressors to a temperature and pressure above the triple point and ther' cooled to condense the gas to a liquid. The liquid prodt t is drained from the accumulators to 1 of 2 withdrawal positions. The liquid product is fed to 2.5 .10- or 14-ton cylinders at the withdrawal positions. The capability also exists to withdraw product to str.a!'er cylinders.

Each withdrawal position includes a scale and an air-operated cart used to move the cylinders between the withdrawal position scale and the storage pad immediately outside the building.

Cylinders are moved one-at-a-time. and are not moved over other cylinders on the storage pad.

All !! quid-filled cylinders are cooled outdoors on the storage pad tc tle west of the LAW station.

The withdrawal system is piped with permanently installed nickel-lined steel or monel. The piping manifolds are heated by steam or electric heaters to ensure continued flow of the liquid UF,.

Larger valves are the G-17 design, while small valves are of several designs.

Although arranged as 2 loops, there is enough installed flexibility to allow many different flow paths to meet the product demand or to accommodate equipment unavailability. In addition to the flexibility afforded by crossover piping, the LAW station includes a backup Worthington compressor that can be used in either loop. If this compressor is oced. another Worthington compressor .nay im used as the first stage compressor.

i l The systems and equipment associated with the A-Loop of the LAW station are described in more

! detail Miow. The major system corr.conents are described first. 2nd tren support systems for those components are described. The equipment associated with the B-Loop is identical to the A-Loop. and is operated in the same mai.ner.

l l Table 2 shows the alarms on the various portions of the A-Loop.

. A 2975A# (216-%) .

NUCLEAR CRITICALITY SAFETY APPROVAL

- l'SE BLACK INK oNLY .

rage 4 er:::

PART A: REQUEST FOR NUCLEAR CRITICALITY SAFETYEVALUATION eCONTT%1Tth Table 2. LAW A-Loop Alarms Equipment item / Interlocks / Alarms:

Subsystem: (All alarms in ACR)

. Allis-Chalmers AC compressor discharge high pressure alarm (7.5 PSIA)

Compressors a AC compressor discharge nigh-high pressure alarm (10 PSIA)

Coolers initiates high pressure vent after 1 minute Seal exhaust low /high AP alarm N: buffer gas low pressure alarm N: buffer gas high flow alarm Cooler process gas discharge high temperature alarm Cooler Coolant system high pressure (125 psia) trips all compressors AC compressor motor load alarm AC compressor tube oil high temperature alarm ,

Wonhington Seal exhaust low /high AP alarm Compressor to N: buffer gas low pressure alarm

Condenser N

buffer gas high flow alarm l l Worthington compressor motor load alarm i Wonhington compressor lube oil high temperature alarm l Vent line high pressure alarm- 7.5 PSIA l Condenser Freon low temperature alarm - /5# (132*F)

Accumulators and AIC-2408 (Gamma spec) - trips FSV-2350, alarms in ACR cylinder fill Accumulator High Level Alarm - LAH-2341 Scale weight semoint alarm I

1. Comoressors

The arrangement of compressors is illustrated in Figure 2. A modified Allis Chalmers AC 12-5 l i

compressor normally provides the first stage of centrifugal compression. Process gas is passed

! to the AC compressor through a pressure control valve and an automatic isolation valve. The

! operator selects which header is to be used as the process gas supply by opening a manual block i valve at the heade.. The pressure control valg is used to control the pressure at the compressor  !

inlet to prevent surging of, or high loads on, the compressor. The automatic isolation valve will close on an HPV isolation signal, isolating the LAW system from the header. l'his valve may also

' be closed at the discretion of the operator from the Area Control Room (ACR) er Local Control Rmm (LCR). The HPV isolation signal and functions are described in more detail in Section 10.

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. A.2975A# (2-16-96) -

l NUCLEAR CRITICALITY SAFETY APPROVAL

-(JSE BLACK INK oNLY -

Page 5 of: 0  !

PART At REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION ll

.r m t m The AC compressor (or possibly a Worthington compressor if the spare Worthington A/B compressor is used as the second stage compressor) compresses the process - gas from approximately 15 psia to 5-10 psia. To remove the heat of compression, the gas is cooled by a gas cooler. The Freon coolant system which serves the gas cooler is described in Section 5.

- The second stage of compression is supplied by a high speed Worthington (JS-697) centrifugal 4

compressor. The Worthington compressor compresses the process gas from approximately 1-10 psia to approximately 35 psia, with a discharge temperature of approximately 350*F. This compressed gas is then fed to the condenser. In the event of a failure of a Worthington compressor, a spare compressor is available which mr.y be used by repositioning valves.

Both the AC and Worthington compressors use constant speed motors with mechanical speed increasers for their motive force. It is currently planned that the motors and speed increasers be replaced with variable speed motors. The variable speed motor for the AC compressors may be air cooled. while the variable speed motor for the Worthington compressors may be water cooled.

The motors will be attached to the compressors via a rotating shaft. A block valve will be installed on the water line to the water-cooled compressor motors, if used. and this valve will be closed when the motor is not running.

Each stage of compression has a recycle control val"e to adjust the system pressures based on the flow rate to the condenser. While the recycle valves were designed to be operated under automatic control, they have been typically operated unde. manual control. Change > are being made to tim LAW control systems to improve the perfoimance of the system under automatic control.

The compressors include alarms on several out-of-tolerance conditions associated directly with the compressors or with the LAW s) stem withdrawal loop. Compressor trips are provided for low lube oil pressure, high compressor temperature, overcurrent, and undervoltage.

Double-walled expansion-joints are located on the suction and/or discharge lines of the compressors. The space between the expansion joint bellows is buffered and connected to the buffer monitoring and alarm panel to pmvide immediate detection of expansion joint single-wall failure. The Buffer Gas System is desciibed in Section 7. The compressor and motor bearings are lubricated by the Lube Oil System which is described in Section 6.

The LAW station compressors are le?ted inside a housing on the sccond floor. Thermostatica'y controlled electric and steam heaters are used to control the heat in the compressor housing.

November 16,1996 NCSA-0333_017. A00 A-2975A# (2-16-96) .

NUCLEAR CRITICALITY SAFETY APPROVAL

- UsE BLACK INK oNLY -

Pige 6 e(22 lPART :) REQUEST FON PCCLEAR CRITICALITY SAFETY EVALUATION -

<cavmum -

2. Condensers and Accumulators As illustrated in Figure 2, after second-stage compression the UF is cooled to a liquid state in a condenser. The flow rate to the condenser may be controlled by two flow control valves in

, parallel. One flow control valve provides rough control of flow rate, while the other provides fine control of flow rate.

The process gas is cooled from approximately 350 F to approximately 150 F in the condenser. Th Freon coolant system which serves the condenser is described in Section 5. The process gas condensers are cylindrical and have u e approximate dimensions of 10-feet by 8-inches I.D.

The nuclear criticality safety of equipment and operations handling liquid UF is based on moderation control which limits the H/U ratio to 0.088. This is done by limiting the pressure in the condensers to less than 60 psia which ensures that t'ie H/U ratio is 0.088. Noncondensible gases are vented from the condenser to the vent headet via a pressure control valve.

Two accumulators are provided in each spression loop. Each LAW system accumulator has a capacity of approximately 13,000 lbs of UF.. The inside diameter of the accumulators is approximately 8 inches. Noncondensible gases are vented from the accumulators to the vent header via a pressure control valve.

The discharge outlets of the two accumulators are joined and pass through a liquid drain valve to l

l the withdrawal rnanifold. The liquid drain valve automatically closes if a gamma spectrometer detects an assay outside of the limits of target assay. This valve may also be closed at the discretion of the operator from the withdrawal room, ACR, or LCR. The gamma spectrometer is described in Section 9.

The condensers and accumulators are located in heated housings, as are the withdrawal manifolds.

The condenser / accumulator housings are approximately 19-feet by 7-feet, with a height of approximately 8-fect. The condenser and accumulator housings and the pipe gallery are heated with steam that u controlled thermostatically. The vertical piping housing and the withdrawal manifold housings are :lectrically heated.

A cross-tie line is present which allows the accumulator of one of the LAW Station loops to discharge to the other loop's discharge manifold. This line has doubie block valves, and these valves are physically locked closed when two different assays are being withdrawn at the LAW station.

i

. 1

. A 2975A# (2-16-96) -

4 NUCLEAR CRITICALITY SAFETY APPROVAL

. l'SE BLACK WK oNLY .

a' PART A: REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION Page 7 ofO

. wmim

3. Withdrawal Manifolds

]

1 Each withdrawal manifold is equipped with several manually or pneumatically operated valves:

1) Block valve to discharge the liquid UF. to cylinder

. 2) Evacuation valves to remove UF from the -igtail or to provide evacuation for any part of the withdrawal loop.

3) Nitrogen purge valve. _

! 4) Cross tie valves which allow the filling of cylinders at one withdrawal station from the I other LAW station loop's accumulators. l The cylinder being filled is connected to the Gli manifold via a pigtail. This pigtail is electrically l ,

heat traced to prevent freezeout of the UF in the pigtail. The cylinder valve is also electrically I heated via a valve cap heater.

Each cylinder pigtail can be isolated by two air-operated valves in the case of a rupture. The i cylinder safety valve (air-to-close) is attached to the cylinder valve while the manifold safety valve j (air to-open) is attacned to the withdrawal manifold. If the two UF detectors at a withdrawal station alarm, the control circuit will close the two valves at that station and turn off power to the heat tracing. A compressed air reservoir is present in the system to ensure that compressed air is available to close the cylinder safety valve in the event of a loss of plant air.

4. Withdrawal Positions Cylinders being filled are mounted on air-operated carts. Compressed air is supplied to the air-operated cart through a hose. A scale is provided at each withdrawal position. Digital readouts l

are provided at the scale anri at the ACR. During the filling operation, the cylinder weight is monitored at least once every hour to ensure that the cylinder is not overfilling. An alarm on the scale is preset to alert the operator when the cylinder is almost full.

The scale pit is approximately 43-feet by 10%-feet, with a depth of 27%-inches and covered with steel door plates. The scale pit is filled to a depth of 6 inches v'ith Raschig rings. The LAW scale pit has a 16 mch diameter. 24-inch deep sump, from which a submersible automatic sump pump discharges to a U-tube, known as the scale pit reservoir ta'1k. A mechanical float arm is attached to the sump pump which, when raised. starts the pump. This Goat arm is contained within a otrforated metal box, melsuring 8-inches by 4%-incSs. with a height of 17%-inchts.

The remaining volume of the sump is filled with Raschig rings.

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A-2975A# (2-16-%)

NUCLEAR CRITICALITY SAFETY APPROVAL

. USE BLACK INK oNLY .

' ~

LPap 8 of 22 (PART A: IRENUEST FOR NUCLEAR' CRITICALITY SAFETY EVALUATION memum The following scale pit modifications relevant to nuclear criticality safety should be performed per POEF-831-96-1036:

1. The existing scale pit sump pump discharge line should have a flow switch installed which

. will give a visual and audible alarm in an adjacent room in the event of flow in the pipe.

2. Moisture detectors should be installed in the sumps to indicate the presence of moisture with a visual and audible alarm in the adjacent room.

The scale pit reservoir tank is in the shape of a horizontal "U" with two ten-foot sections of 10-inch ID pipe connected by a curved section of 8-inch ID pipe. The separation of the two ten-foot I

sections of pipe is 3-feet, center-to-center. The scale pits and reservoir tank are inspected weekly for solution. A sight glass is present on the reservoir tank to show the presence of water. If l

liquid is found in the reservoir tank, it is sampled and analyzed for presence of 235U and it's concentration prior to disposal. If the liquid contains more than 5 grams *U per liter, the

! solution is drained into 5-inch maximum alameter polybottles and stored in approved container holders. If the liquid contains less than 5 grams 235U per liter, the liquid can be drained to an unfavorable geometry. The drain line for the scale pit reservoir tank to the storm water sewer is locked and chained in the closed position to prevent inadvertent draining of the reservoir tank.

! The sump is checked for automatic operation and the line for clarity by pouring water into the sump once a month. A safe boundary line is painted on the floor around the reservoir tank at a l distance of approxunately 3 feet. The sump pump is automatically disabled when the gas release alarm system has been manually actuated, or if both smoke heads above a withdrawal station fire.

The withdrawal positions are protected by a wet-pipe fire sprinkler system.

5. Coolant Svttems As illustrated in Figure 2, the process gas stream is cooled after the first stage of compression to remove heat of compression. After second-stage compression the UF. is cooled to a liquid state in a condenser. Cooling is provided by two systems, one which removes the heat of compression and the ottier which provides the proper temperature for the condensers. Other than minor instrumentation differences, these two coolant systems are identical. Each coolant system utilizes R-114 coolant, which in turn is cooled by recirculating cooling water (RCW). No pumps or compressors are used in these coolant tvstems. The coolant pressure is maintained at least 5 psi above the UF pressure to pre,ent UF from entering the coolant system, and at least 5 psi above the RCW pressure to pr: vent vater from entering the coolant system.

.. _ _ _ _ .~ _ . ._. _ _. _ _ _ _ _ _ _ _ _ _ _ _

A-2975A# (2-16-96)

NUCLEAR CRITICALITY SAFETY APPROVAL

- t'SE BLACK INK oNI,Y .

PART A: REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION Page 9 at::

<cwrmw The protective devices for each coolant system include:

Pressure switch which alarms and closes the RCW supply valve to the Freon condenser on ,

low R-ll4 pressure (75 psia) to prevent water from entering the coolant system. '

Pressure switch which alarms and closes the RCW supply valve to the Freon condenser on '

. high RCW pressure to prevent water from entering the coolant system.

Pressure switch which alarms and trips all process gas compressors on high pressure (125 psia) to prevent Worthington compressor overheating (process gas cooler coolant system only). ,

Pressure switch which alarms on low differential pressure between process gas and coolm -  !

system, and )

A rupture disc to prevent coolant system over pressurization.

6. Lube Oil System The AC compressors and the Worthington compressors are lubricated by a lube oil system. Oil is pumped from an unfavorable geometry reservoir, through an oil cooler, to the compressor and ,

l motor bearings. An alarm and compressor motor trip will occur on a low oil pressure, and an

! alarm .will occur on a high lube oil temperatura from a compressor bearing. Refer to NCSA-PLANT 054 " Lube Oil". .

l

7. Buffer Gas Systems The monitoring and control panels for the buffer systems provide a means of identifying failures or leakage 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, i

l The buffer gas is supplied at two pressures because of the large pressure differentials across the

compression and condensation system. The high pressure buffer panel provides gas at 35 to 40 j- psia to all components after second stage compression and a low pressure panel supplies gas at 10

psig to the other components.

q The G-17 valves in the high pressure system cannot withstand the full range of differential pressures that might be seen with a single source of buffer gas. The buffer gas is supplied to these vtives at a variable pressure ..ne.d cn the process gas presstee.

A-2975A# (2-16-96) l NUCLEAR CRITICALITY SAFETY APPROVAL  !

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Page to er j PART A: REQUEST FOR NUCLEAR CRITICALITY SAFEIY EVALUATION errmuw

8. Seal Control and Buffer System  !

The seal buffer system provides dry, clean air and nitrogen to the compressor seals. Seal exhaust passes through three parallel alumina traps, two seal exhaust pumps, and is vented to the )

atmosphere - roof level. The alumina traps are constructed of 5-incl , rehedule 40 piping, and l

• are approximately S foot long. The center-to-center distance between adjacent traps is (

approximately 2.5 feet. A safe boundary line is painted around the seal exhaust pumps and aluniina traps. This line is 5 feet from the center of the pumps and 6 feet from the center of the chemical traps.

Each pump has a motor and drive assembly and is placed on a concrete pad which is elevated above the door. Each pump is connected to an oil separator on the discharge side. and three  !

alumina traps on the suction side. Connections are made by 4-inch diameter flexible metal tubing and 3 and 4 inch diameter piping. The pumps are spaced at nominal 7.5 foot intervals (center-to-center). The oil capacity (assuming the overflow is blocked) of each pump, excluding the piston cylinder, is required to be less than or equal to 11.5 gallons. If the capacity is greater than 9.2 gallons, an overflow line is required to limit the capacity to a maximum of 9.2 gallons. Oil is added to the pumps individually (the system is not equipped with a common oil fill header).

The reaction of UF, and oil in the pump produces a suspended black precipitate of UF,+ oil which reduces the oil's lubricating properties. The concentration of UF + oil particles can reach a point where the p.,mp will fail. Oil is drained from the seal exhaust pumps by a drain line to a iavorable geometry container (NCSA-PLANT 025) or a limited safe volume container (NCSA-PLANT 045).  ;

l Pwcedures require that no more than one uranium-bearing container (e.g., contaminated oil or alumina) be in motion at a time. Such containers must be transported along safe paths (white lines). Containers are not permitted to be transported across safe boundaries (orange lines) except when approaching an empty storage location or seal exhaust overflow line. The containers must J be moved directly toward the storage location or seal exhaust pump overflow line: that is. the approach must be in a direction perpendicular to the orange line. A container can leave the safe ;

path only when clear of a safe boundary by more than 6 inches. l Alumina is removed by taking the top off the trap and using a fasorable geometry vacuum.

Vacuum cleaner operations are covered in NCSA-PLANT 012.

NGA-0333_017.A00 October 11.1996 f

. A 2975A# (216.')6)

NUCLEAR CRITICALITY SAFETY APPROVAL

- l'SE BLACK INK ONLv -

PART A: REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION hee 11 or::

er NTINtTth

9. Assav Monitoriny Eauioment The assay (enrichment) of the withdrawal is monitored with mass and gamma spectrometers. The mass spectrometer autom.itically traps process gas from the AC compressor cooler discharge, analyzes the gas, and records the assay every five to six minutes. Each hour. an operator records  ;

. the current assay on the withdrawal data sheet.

e The gamma spectrometer monitors the Dow to the withdrawal manifold with probes on the liquid line before it enters the manifold. The assay is recorded on terminals at five to six minute  ;

intervals. if the assay exceeds the predetermined assay serpoint for a cylinder size. the air--

operated valve located between the accumulator and the withdrawal manifold is signaled to close. ,

Due to an internal algorithm, the gamma spectrometer will not respond until the actual assay value is +0.05 abose the setpoint value. U-tube samples are also taken at least every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> as a redundant means of assuring correct assay.  ;

When gamma and mass spectrometer are out of service, laboratory samples are collected and analyzed for assay every 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at the LAW loop inlet with assay results available within t hours.

10. High Pressure Venting (HPV) Isolation The LAW station has high pressure venting (HPV) circuitry to relieve the system pressure in case of emergency. If the HPV circuitry is actuated, the compression loop automatically vents back thr~.:gh two inch lines to the vent return header the Dow control valves :o the condenser close.

the condenser vent valve closes, the two air-operated valves on the cylinder pigtail close. power to the electric heat tracing is de-energized, and the station suction valve closes.

l The HPV circuits are manually actuated on indications of UF, leakage or excessive pressure. The circuits may be initiated from the withdrawal room, the ACR, or the airlock on the cell floor near the compressors. An automatic activation of the HPV occurs when both smoke detectors above l any one LAW compressor fire or on a first stage compressor high discharge pressure. A high

( pressure switch at 7.5 psia alarms the condition while a high-high pressure switch at 10 psia actuates the HPV,

11. Outleakage Detection Svstem LAW is monitored with three smoke detection systems w hich ate used to monitor the withdrawal l

facilities where operating pressures exceed or may exceed atmospheric pressure. The first system l is a smoke detection alarm system that is an integral part of the CADP system. It molitors the L compressor and withdrawal areas. This system 7erforms no automatic isolation function. The detector heads in the CADP system are fired and tested continuously.

i

l l

! . NCS A-0333_017. A00 October 11.1996 A-2975 A# (2 16-%) ,

NUCLEAR CRITICALITY SAFETY APPROVAL j

- USE BLACK WK ONLv -

Page 12 er::

PART A: REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION ,

.cmrmm t

The high voltage smoke detector system is designed to alarm on outleakage in the accumulator /

condenser area. Two detector heads are placed in each UF condenser compartment and eight outleakage detector heads are located in the accumulator / condenser areas and in the pipe housing l

going to the condensers. The microprocessor-based system generates an ala m condition when

! UF is detected. The control unit monitors detector performance and can be used to test the  :

system. The detector heads in the high voltage system are fir <.d and tested continuously.

l ,

Pyrotronics smoke detector systems monitor the compressor and withdrawal areas. The compressors anJ withdrawal stations are moniivred by heads over each compressor and each position. Actuation of any two heads in the compressor area initiates high pressure venting and actuates after a two-minute delay. Firing of two heads at a withdrawal position will cause l

isolation of the cylinder pigtail and an alarm. The Pyrotronics system does not fire continuously ,

~

! - and the detector heads are tested quarterly. The actual circuitry is tested annually by alarming detectors and verifying operability of the entire system. The withdrawal positions are also monitored by a closed-circuit television from the ACR. 1 l

12. Ventilation System The Low Assay Withdrawal room utilizes a single exhaust duct on the north wall of the withdrawal room. Air is drawn through this exhaust duct. through a set of HEPA filters. through the exhaust fan and is discharged into the track alley just north of the withdrawal area roll-up Mors. The exhaust fan is turned on during cylinder change operations to expel small quantities ,

of UE. that may escape during the disconnecting of pigtails. The fan capacity is 5.000 CFM.

which will perform a complete air change every 2 minutes. Favorable geometry gulpers may also be used to remove trace quantities of UF, from the air.

Control switches for the exhaust fan are located inside and outside the withdrawal room so that ventilation can be shut down in the case of a UF, release. The LAW ventilation system is automatically shut down when the gas release alarm system has been manually actuated. or if both smoke heads above a withdrawal station fire. The HEPA filter is NDA scanned yearly. and replaced when necessary.

13. Cylinder Change Oneration i

Two personnel must be present when a cylinder is connected or disconnected and they are required to complete the Withdr ral Cieck List. They must v.rify that each item on the U.cck list is performed sequentially.

When cylinders are brought into LAW, they are first verified to be of the correct size (enrichment merictinnd for the material to be withdrawn. Cylinders are then inspected externally for

i l i NCS A-0333_017. A00 October 11.1990 )

j A-2975 A# (2-16-96) .;

I

('

NUCLEAR CRITICALITY SAFETY APPROVAL

] . csE stack INK ostv .  ;

1 i

PART A

REQUEST FOR NUCLEAR CRITICALITY SAFETY EVALUATION rage 13 of:  !

a ,co m u m  ;

j heel mass inside the vessel. Per ORNL/CSD/TM-284,22 Kg of water is needed to achieve a i critical configuration for 5% enriched UO,F,(or 135 Kg of HF for 5% UF.).

I i e

j Next, a pigtail is attached to the cylinder and the withdrawal manifold. Clean. virgin Tetlon j gaskets are used in making these connections. A leak check is performed on the pigtail as 'well j j, as a pressure test. The air-operated pigtail c.ylinder valve and the cylinder valve itself are checked for leakage through the valve seats by applying nitrogen. The cylinder valve is then opened and ,

l the pigtail pressure is checked to verify clarity. This check verifies that undesirable non- )

{ condensibles are not present in the cylinder and (nat the cylinder is not leaking. l t 4 i

! When a cylinder is to be disconnected, the cylinder valve is closed and the UF is evacuated from j

! the pigtail. An acceptable leak rate must be obtained to assure that all the liquid UF has been l

i removed from the pigtail and to assure that the cylinder valve is properly seated and not leaking.

l After the cylinder is disconnected and weighed, a valve protector shield is installed over the-l cylinder valve. Cylinders are then moved outside by air-operated carts and placed into cradles by

overhead cranes to allow the cylinder to cool. l

!- l in the event that a leaking cylinder valve seat is found after fill, the pigtail safety valve is closed 1 l

and the pigtail purged and evacuated. The pigtail is then disconnected at the pigtail safety valve.

After the cylinder has cooled, the defective cylinder valve can be safely changed.

i

A-2975 A# (2-16-96) t _

NUCLEAR CPJTICALITY SAFETY APPROVAL

- USE BLACK WK ON*LY.

PART A: REQUEST FOR NUCLEAR CRIT]CALITY SAFETY EVALUATION - Page14 or::

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NCSA-0333_017.A00 October 11, 1996 A-2975Ai (2-16-96)

NUCLEAR CRITICALITY SAFETY APPROVAL USE BLACK INK ONLY -

PART Ai REQUEST FOR NUCLEAR CRmCALHY SAFETY EVALUATION rage 15 or::

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ORIGHuL l NCS A-0333_017. A00 October 11, 1996 A 2976# (216.% ,

1 NUCLEAR CRITICALITY SAFETY APPROVAL  !

- L'SE BLACK INK ONLY .

PART B: NUCLEAR CRITICALTTY SAFETY APPROVAL Pace 16 et 2 ,

THE FtssioNABLE MATERIAL oPERAT10N DESCRIBED IN PART A IS APPROVED SUBJECT To 'n{E LIMrrs AND l CoNDrrloNs PRoVIDED BELoW:

1

LAW Station I

REOUIRENfENTS:

"1. The Law Station shall be limited to a maximum enrichment of 10%

2 "U.

"2. The Scale Pit Reservoir Tank shall be limited to a maximum enrichment of 5.5 % "'U. l l -3. Enrichment and Fill Limits for cylinders shall follow Table 1 of this NCSA Part A. Prior l

to filling a cylinder, an independent verification shall be completed to ensure that the proper cylinder is being used for the enrichment to be withdrawn.

"4 The Scale Pit sump pump shall be de-energized when material is being withdrawn with an enrichment greater than 5.5 % "'U.

! *5. The affected portion of the LAW Station shall be evacuated prior to restart after the system has been opened to the atmosphere.

l

6. The HEPA filter on the LAW room exhaust vent shall be NDA scanned annually and I j following a release of UF estimated to exceed 50 grams. The filter shall be replaced if I it is determined to have a "U mass exceeding 300 grams.

I Analped By: Q4Cs Engmeeri k Revi By (NCs En eer)

_ ate A , Date /9 + l \

l R viewed By: (NCs a nager) 8!f /

i b ,

Date: 2P b '

/~ l' l-Reviewed By

(operating Group) Revie d Bv: (safety Analysts Depanment Manager Daw: / [ -

Date: / % f['

./ q le Date: M/

Acknow ra (Depaitment h , t Iha.c d. understand. a agth the imits and NCSA Number conditions a c. 9333 )gyg)

_< .,.. .s...

W / u _ . _ _ . _ _

NCSA-0333_017.A00 November 18,1996 A-2976A# (2-16-96)

NUCLEAR CRITICALITY SAFETY APPROVAL

- UsE BLACK INK oNLY .

LPART B': NUCLEiR CRITICALITY SAFETY APPROV L L Pop 17'of 22:

r comam-

• 7. Both the Gamma Spec System and the Mass Spec System should be operational during withdrawal operations. If either system is out of service, U-tube samples shall be taken at least every eight hours as a redundant means of assuring correct enrichment. If both systems are temporarily out of service, samples shall be taken every 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> with enrichment results available witla 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

• 8. The coolant pressure shall be mamtained at least 5 psi above the UF6 pressure and at least 5 psi al ovc the RCW pressure.

• 9. The RCW shall be valved off, drained, ano the valve left open, prior to draining the R-11, coolant system. The RCW shall remain valved off, with the drain line open, until the R-114 is returned to the systerr..

• 10. The maximum UF6 pressure in the LAW Station shall be 60 psia.

• 11. The scale pit shall be filled to a minimum depth of 6 inches witu Raschig rings that meet ANSI Standard 8.5.

• 12. The scale pit sump pump float arm shell be housed in the perforated metal box described in Part A. The remaining volume of the sap shall be fined with Raschig rings that meet ANSI 8.5.

• 13. The scale pit and reservoir tank shall be inspected weekly for solution. If found, the solution shall be sampled for uranium concentration and enrichment and removed.

• 14. The scale pit sump pump shall be checked for automatic operation and line clarity once a i month. l l

• 15. The Raschig rings in the scale pit shall be inspected for settling and damage on an annual j basis and following any UF. release exceeding 50 grams. If the rings are exposed to uranium-bearing materials or any corrosive agent (e.g., acid solutionsh they shall be replaced with certified rings or tested and verified that they meet the requirements of ANSI /ANS-8.5.

• 16. The scale pit and equipment housings shall be maintained free of uranitim buildup.

Inspections shall be made after any UF 6release exceeding 50 grams and contnminated areas cleaned when fcund. Housir~ need only be inspected if release occurred within the housing.

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f NCSA-0333 017.A00 November 16,1996 '

A-2976A# (2-16-96)

NUCLEAR CRITICALITY SAFETY APPROVAL ,

. USE BLACK INK ONLY -

PART'BfNUCLEAR CRMCALITY SAFETYLAPPROVAL 1 ]t jPspisd22 connnum i

l

• 18. Prior to discharging the contents of the reservoir tank, a representative double sample shall  !

i be obtained for analysis. If the lab analysis results indicate a greater than 5 g mU/ liter concentration, the drain line between the reservoir tank and the storm sewer shall be maintamed locked and chained in the closed position and the contents shall be drained into i geometrically favorable containers approved per NCSA-PLANT 025 or NCSA-PLANTO45.  ;

l

19. The oil capacity of a seal exhaust pump must be measured and documented to be below l l 11.5 gallons prior to installation in LAW. Existing pumps must be verified and documented to have a oil capacity below 11.5 gallons. If a pump capacity exceeds 9.2 gallons then an overflow shall be installed to limit the volume of oil to 9.2 gallons or less.

• 20. If overflows are required (per #19 above), they shall be verified not blocked (via valve closed or obstruction) whenever oil is added. i l

21. The LAW System shall be monitored with smoke detection systems for leakage of UF at j the compressor, withdrawal, and equipment housings.

• 22. The LAW cylinder room ventilation system shall be shut down (automatic or manual) in

! the event of a UF leak in the LAW station cylinder room.

l

! 23. A high pressure venting system shall be installed at the LAW Station with the capability of manual and automatic actuation initiated either by the firing of any 2 Pyrotronics System l

j smoke detectors or a first-stage compressor high discharge pressure.

t

• 24. Prior to withdrawing UF.inte a cylinder, the cylinder shall be visually inspected for damage, weighed and cross-checked against the MC&A's net weight.

• 25. Prior to withdrawing UF into a cylinder, a vacuum test shall be performed on the cylinder at a minimum vacuum of 10 inches of mercury.

! *26. To prevent violating the enrichment limit on cylinders, the double block valves in the cross-i tie line between the manifolds of the A & B loops shall be physically locked closed when two different enrichments are being withdrawn into two different size cylinders.

l.

-27. Alumina shall be transfernxi from the Seal Exhust Traps using an NCS approved favorable geometry vacuum (NCSA-PLANT 012).

• 28. Prior to its use, a second knowledgeable individual shall independently verify an approved j vacuum is staged for use when removing alumina.

A J.976A# (2-16-E

=

NUCLEAR CRITICALITY SAFETY APPROVAL

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1 Page U or PART B: ' NUCLEAR CRITICALITY SAFETY APPROVAL

<nmem j l

"29. Only small diameter containers '(see NCSA-PLANT 025) or limited volume containers (see ,

l NCSA-PLANT 045) shall be used to handle, catch oil from overflows, and store uranium bearing material in the seal exhaust area. Drip pans with a depth less than one inch may also be used.

- *30. Approved containers shall be spaced per NCSA 'l ANT 025 or NCSA-PLANT 045 and kept ,

j at least 2 feet apart (edge-to-edge) from seal exhaust pumps and uranium bearing ,

equipment. J "31. A second knowledgeable individual must verify that only NCSA-PLANT 025 and NCSA- f PLANT 045 approved containers or drip pans with less than one inch depth. are used for l the collection of oil or alumina.

ADMINISTRATIVE AIDS:

i

32. No temporary or permanent changes shall be made to the physical configuration or operating controls of LAW as described in Part A and as required by Part B of this NCSA without formal and written approval from the NCS Section.

33. The NCS requirements marked with an asterisk (*) shall be included in the applicable sections of the appropriate operating methods. Requirements may be re-worded in the t

procedures to improve clarity for use by operating persont.ei.

1 i

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october ti.1996 O Fj l. ~ .. m i. z.r,nCSA.0333_oi7. Aoo

. l

- c . .

NUCLEAR CRITICALITY SAFETY APPROVAL

- USE BLACK INK oNLY -

1 PART C: BASIS AND DOUBLE CONTINGENCY CONTROL MATRIX Pare :0of22 i l

Low Assay Withdrawal Station )

BASIS FOR NUCLEAR CRITICALITY SAFETY The nuclear criticality safety of the Low-As ay Withdrawal (LAW) Station is based primarily on  ;

mass, concentration, and moderation control. The LAW Station is used to remove gaseous low- l l assay UF. product from the cascade, compress and condense the gas to the liquid phase via cooling, and drai1 the liquid into cylinders. Enri;hment in the LAW Station is limited to a l maximum of 10%. A number of administrative controls as well as engineered safeguards and passive barriers are in place to prevent the loss of control of basic parameters affecting nuclear l criticality, i l ~

l DOUBLE CONTINGENCY CONTROL MATRIX The following table associates the numbered requirements listed in NCSA Part B with the individual contingency events analyzed in the NCSE. Control A requirements are those j requirements which are assumed to fail as the first unlikely or contingent event in each scenario. )

Requirements listed under Control B are needed to ensure suberiticality in the event the Control A requirement is lost. In some cases. Controls A or B may contain multiple requirements. If multiple requirements are separated by plus (+) signs, all of the requirements are necessary in order to maintain the control. If multiple requirements are separated by the word "or". then either one of the requirements are sufficient to maintain the control. Regt;irements for administrative aids in NCSA Part B (e.g. NCS Postings. boundary lines, etc.) are not included in this matrix.

i The cascade and LAW structures, systems and components (SSCs) providing single barrier protection have quality requirements and boundaries as described in the SAR Section 3.8.

As noted in SAR Section 5.2.2.3, ' Process Evaluation and Approval': There are three operations which do not meet the double contingency principle as described earlier in this section. However, r* ~ ~

these operations have been evaluated to be safe, and are discussed in thefollowing paragraphs.  ;~

These operations are: the handling, storage and transportation of large product cylinders; l operation of the cascade equipment; and handling of large cascade equipment items (e.g., *:: '

compressor, converter, G-17 valve, etc.) which have large deposits of uranium. .

The double contingency control matrix includes references to certain passive barriers (PB) which y are either described or referenced in the NCSA Part A. These items, while not specifically listed jm '

in the NCSA Part B requirements, are still considered "NCS controls" for the purposes of '. 4 i

satisfying the double contirigency criteria. The passive barriers utilized in the double contingency control matrix are defined below: b(

Prepared By - Arapst: NCS A No.:

E // O: i LA? h,/i  ? mmy

November 18,1996 NCSA-0333_017.A00 NUCLEAR CRITICALITY SAFETY APPROVAL UsE BLACK INK oNLY -

L Page 21 of 22

'PART CiBASIS 'AND DOUBLE CONTINGENCY CONTROL MATRIX (cont.)

l Low Assay Withdrawal Station PBI: The design of the RCW system and the R-114 coolant system in the LAW Station is such that there is no direct connection between the RCW ard the process gas streams. Two separate

leakage paths would have to develop (RCW to R-114 in the condenser and R-114 to process gas stream in the cooler or condenser) in order for there to be a connection.

PB2: The design of the system and cylinders minimize the risk of a major leak of process gas or i liquid UF and 6 the inleakage of wet air.

PB3: The design of the system and cylinders (filled under moderation control) are of .'worable

( geometry for 10% 2"U.

PB4: The scale pit is covered by a steel plate.

l Note 1: A release of liquid UF will flash to gas almost immediately and react with moisture in the air.

forming UO 2F: and HF. The UO F2Will late P out on surfaces throughout the LAW cylinder l

i room.

UE1: Cylinders me cleaned and conditioned at the X-705 building. Procedural controls are in place i

at X-705 (NCSA-705_039) which prevent a cylinder from containing water after it has been conditioned.

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