ML20206R945

Forwards Pages15-159 Through 15-174 to Include in Chapter 15 of Siemens Power Corp License Application.Pages Provide Summary of Criticality Safety Analysis for Processes Carried Out in Lagoon U Recovery & Solids Processing

ML20206R945
Person / Time
Site:	Framatome ANP Richland
Issue date:	01/07/1999
From:	Edgar J SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
JBE:99:003, JBE:99:3, NUDOCS 9901220200
Download: ML20206R945 (17)

Text

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SIEMENS 1

January 7,1999 l

JBE:99:003 l

i U.S. Nuclear Regulatory Commission j

Attn: Document Control Desk Washington, DC 20555 i

Gentlemen :

Subject:

Part ll License Changes, Docket 70-1257 Enclosed for your information and to include in Chapter 15 of Siemens Power Corporation's (SPC) license application are six copies each of pages15-159 through 15-174. These pages provide a summary of the criticality safety analysis for the processes carried out in the Lagoon Uranium Recovery and Solids Processing Facilities.

If you required additionalinformation, please contact me at 509-375-8663.

Very truly yours, 4

Jameo B. Edgar Staff Engineer, Licensing i

/p9 Enclosures t

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9901220200 990107 E

PDR ADOCK 07001257 1

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C PDR 42v=

x Siemens Power Corporation 21o1 Horn Rapids Road Tel:

(509) 375-8100 Richland, WA 99352 Fax:

(509) 375-8402

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l SiemenS Power Corporation - Nuclear Division EMF-2 l

SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 REV.

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15.5 Laaoon Uranium Recovery (LUR) and Solids Processina Facility (SPF)

The LUR and Solids Processing process equipment is located in the LUR/SPF Building directly west of Lagoon 4. The processes are used to recover uranium from both the liquids and the settled solids in the various lagoons at SPC.

1 15.5.1 General Safety Conditions 15.5.1.1 Criticality Safety Criticality safety in the LUR and SPF processes relies on controlling the uranium l

i concentration and enrichment of the uranium to less than 140 g U/t and 4 wt% "U, j

2 respectively, in addition, the slurry feed to the SPF contains at least 0.2g Gd/100g 3

U.

I 15.5.1.2 Radiation Protection j

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Chapters 3 and 12 of this application describe SPC's radiation protection program.

Radiation survey equipment is provided and surveys are required when leaving a

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contaminated area. Ventilated hoods and enclosures are also provided to minimize i

contaminants for ALARA purposes. Work area air sampling and regular i

equipment /f acility surveys are undertaken by health and safety technicians. In addition annual training is given on a required basis to SPC personnel who work in or I frequently visit radiation areas.

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15.5.1.3 Fire Protection j

l i Fixed / rate-of-rise temperature sensors which activate fire alarms at SPC and the I

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! City of Richland Fire Department are present in the LUR/SPF, as are portable fire i

extinguishers. Housekeeping is stressed as a means to minimize accumulations of combustible material.

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15.5.1.4 ' Environmental Safety I

I f Chapters 5 and 13 of the license application describe SPC's environmental safety f

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! program which includes measures to clean effluents prior to release as well as to monitor various environmental media (air, soil, groundwater, etc.).

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f pact e aucatur amcaron oars:

January 7,1999 15-159 i

l sPC-ND.3330 947 ( A 1/07/92) i

SiemenS Power Corporation - Nuclear Division eup.2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70.-1257 REV.

15.5.2 Solids Processino Facility The Solids Processing Facility (SPF) recovers uranium from lagoon solids using retrieval, dissolution, separation, and dewatering equipment. The facility uses a dredge or sludge pump to vacuum up and pump lagoon liquids and solids (studges) from the lagoons as a slurry. The slurry is screened, shredded, and pumped into a feed tank. The screened debris is placed in waste drums for disposal.

f f

I l The slurry is thoroughly mixed, with a turbine mixer, and recirculated in the feed tank l

3 to break down the particles, dissolve solids, and solubilize the U While in the recycle l

l loop, the slurry is heated to over 160 F and a 12.5% solution of sodium hypochlorite i

j (bleach) is added at a concentration of about 1 % by volume. The bleach and elevated j

temperature oxidizes the U present in the slurry to a soluble state. Filter aids are added to the slurry and the slurry is then pumped into a filter press to remove the l

l filtrate. The clear filtrate is pumped through bag filters to a filtrate collection tank.

j The filtrate can be recycled back to Lagoon 3 for future processing at the Lagoon i

Uranium Recovery (LUR) facility, or it can be pumped directly to LUR for immediate i

uranium recovery. The de-watered solids, or filter cake, are collected for packaging l

and disposal.

l The major components of the SPF are:

1) The process feed tank with a 10,000 gallon working volume tank (11,486 gallon maximum volume at the overflow pipe).

2) An 80 ft' (600 gal) filter press.

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3) A filtrate tank with a 10,000 gallon working volume tank (11,486 gallon maximum l I,

volume at the overflow pipe).

i l 4) Filters and debris screens (8 inch diameter x 37 to 39 inches tall).

I 15.5.2.1 Criticality Safety i

I A conservative estimate of the average uranium enrichment of the material in the lagoon system is 3.7 wt.% "U. This estimate is based on the weighted average of j

2 I

material placed into SPC processes during the past 5 years. The contents of the lagoons have been characterized for the Washington State Department of Ecology.

1 Lagoons 3,4 and 5 provide feed material to the SPF.

i Lagoon 3 contains the highest quantity of U. The majority of this U is in the large volume of sludge present there. Fines left from a past sand washing operation as well as wind blown sand combined with other metal precipitates dilute the U concentration in Lagoon 3 solids. High gadolinium (Gd) - a neutron poison - concentrations are also present in Lagoon 3.

l AMENDME'

>s'LcAf a0N DATE:

P AGE No :

January 7,1999 15-160 sPC-ND 3330 947 (R 90712)

SiemenS Power Corporation - Nuclear Division suF.2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 REV.

Lagoon 4 has the highest sludge U concentration and the lowest quantity of sludge.

A large portion of the sludge present is from wind blown sand.

Lagoon SA has the lowest sludge U concentration of all the lagoons that have I

appreciable solids. The primary constituents of these solids are ZrF and wind blown sand.

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SPF Process Feed Tank Criticality safety in the feed tank is maintained by control of the average enrichment l

j and concentration of the uranium and the concentration of Gd in the lagoons. The i

l maximum average enrichment of the materials processed in SPF is verified j

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l U/t. Actual enrichment and maximum lagoon liquid U concentration are 3.73 wt% su; 2

i j and 0.4gU/t, respectively. The maximum allowed U concentration in the lagoon i

sludge is 24gU/t and the maximum U concentration in the SPF process is limited to l

less than 140gU/t, which is less than 50% of the minimum critical concentration.

iri addition, the minimum Gd/U ratio previously observed in the lagoon solids is 1.6g Gd/100g U.

Summarv of Accident Conditions l

l j As discussed in Section 15.4.3.1, the lagoon feed streams are controlled such that at least two defenses ensure only safe concentrations are added to the lagoons.

Two changes in the assumed conditions for this process would have a broad impact i

on its safety. These are an increase in enrichment over time and the depletion of Gd over time. Each of those parameters is verified by periodic sampling to ensure it remains at an acceptable leve! during the lagoon decommissioning process, if needed, I compensatory actions will be taken.

I In addition to increases in the U content of lagoon sludges, the following abnormal i

conditions could result in accumulation of U bearing materials in quantities greater than, or in locations other than, those during normal conditions:

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- Higher than expected U in feed material.

- All U in the tank settles with the solids.

i - A leak occurs in any process vessel or piping.

Higher than expected U in the feed material and all U settling in the solids are discussed below, aWENDMENT APP,CATON DATE:

PAGE NOJ January 7,1999 15-161 sPC.No 3330 947 (R-vo7S2)

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REV.

The highest U concentration in the feed material would occur if the feed tank is 100%

full with sludge at 22 g U/t (containing 33% solids). Obtaining this amount of U i

requires sludges at the 95/99 upper limit on U concentration (22 g U/t vs.10.7 g U/t l

for the maximum seen in any lagoon ) to be retrieved at a 2:1 liquid-to-solids ratio instead of the normal 4:1. This would give 3790 gallons (14,346 t) of sludge and j

j 7695 gallons (29,128 t) of lagoon licuid deposited in the feed tank. The maximum lagoon liquid uranium concentration is assumed to be 1 g U/t. The highest actual U concentration in any lagoon liquid is currently under 0.4 g U/t.

i If the feed tank fills to the 11,486 gallons (43,474 t) maximum fill level with no water j

addition, the total U content of the tank would be 316 kg in the sludge and 29 kg in

! the liquid, for a total of 345 kg. The area density of 345 kg U in the feed tank is <3.6 i

j kg U/ ft. Assuming 345 kg of materialin the feed tank, the following conditions i

2 could exist:

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j When the slurry is mixed in a uniform mixture, the resulting uranium concentration l

l is about 7.9 g U/t.

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I if all of the sludge containing all the uranium settles uniformly to the bottom of the e

feed tank, the resulting U concentration in the sludge is 24.0gU/t. It is reasonable i

to expect a uniform U concentration within the feed tank solids because:

1) Mixing occurs during the dredging retrieval process

2) Tank contents are mixed during processing

3) The recirculation pump keeps material mixed j

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4) Settling rates of the U-bearing materialin the solids is fairly uniform (no evidence of preferential settling has been observed).

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I If all of the uranium dissolves into the liquid, the 7695 gallons of liquid would have e U concentration of 11.8 g Ult.

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The minimum critical concentration is 280 g U/t at 5 v>t% 35U enrichment, which demonstrates a very large safety margin in terms of concentration.

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t These conditions beund all potential accidents that could occur in the feed tank.

Leaks occurring in process vessels or piping is discussed below.

Leaks could occur in the slutry feed line, feed tank recycle line, filter press feed line, i

filtrate discharge line, or any of the process vessels. The liquids and solids would fail to the floor at the maximum uranium densities stated above and form a slab I

geometry. The sumps in the SPF are all favorable geometry slabs so a buildup of U-I

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bearing solids will not present a criticality safety hazard even if the concentrations somehow exceed safe values.

In addition to safe concentrations, neutron absorber control is also used as discussed I

below.

I The Gd concentrations in each lagoon were also analged as part of the lagoon f

I characterization activities. The Gd/U ratio in the solids from each of the lagoons that l

< will be processed through SPF is greater than 1.6g Gd/100g U. A large volume of l

lagoon sludge is processed in a single batch. The sludge retrieval process and feed

' tank mixing ensures that the material will be well homogenized.

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Based on the data collected during the pilot test activities, the majority of the Gd has been verified to remain with the solids retrieved and produced during this process.

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Gd, like most neutron absorbers, is most efficient with well moderated neutrons. O.2g Gd/100g U is sufficient to keep k,n, below 0.95 with as little as 3 wt.% water in a j

i UO -H O mixture. During any credible settling process in the feed tank, the solids will 2 2 contain at least 30 wt.% water. Therefore 0.2g Gd/100g U is sufficient to keep the l

feed tank sufficiently subcritical regardless of the U concentration present.

Conclusion in summary:

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The maximum credible U concentration is about 24gu/t for the feed tank.

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The minimum g Gd/100 g U ratio for any solid materialin the feed tank will be at least as high as the 1.6 for the worst case Gd and highest U content reported for the pilot plan filter cake.

i The minimum critical concentration for this material, assuming UO -H O at 4 2 2 wt.% 2'5U, is about 375 g U/t. This provides a factor of safety of over 31 on l

i concentration. No credible mechanism to reach a critical concentration in the l

l solution has been identified.

. SPF Filter Press Criticality safety in the filter press is maintained by controlling the same parameters as described in the discussion of the process feed tank.

i AWENDWENT APPLCATON DATE:

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January 7,1999 15-163 sPC-ND 3330 947 ( A-00792)

Siemens Power Corporation - Nuclear Division EM F-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM 1227, NRC DOCKET NO. 70-1257 REV.

Summarv of Accident Conditions i

Concentration controlis discussed below.

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As discussed above, independent analyses have verified that the SPF feed slurry U concentration is under 24gU/t.

The low slurry U concentrations in the lagoon sludges (and a confirmatory sample l

from slurries quarantined in the feed tank) ensure that all downstream U l

concentrations from the feed tank, (e.g. filter press, filter cake, filtrate, filter bags, and i filtrate tank) are within safe limits needed for criticality safety. The maximum U i

concentration p'ossible in the filter press portion of the process during process upsets l

l is approximately 75 g U/t. The enrichment of the material processed through this 835 i

system is less than 4 wt.%

U as determined by sampling. Concentrations of j

l greater than 350 g U/t are required for k,,,to exceed 0.95. About 375 g Ullis j

required for criticality. Under worst case conditions the safety factor on concentration in filter press material is 5.0 (375/75).

l Neutron absorber control is discussed below.

During normal processing, the filter cake is about 30-50 wt.% water, if one assumes a 3.0 g U/cc UO -H,0 mixture is dried to 3 wt.% moisture, the critical radius of a l

2 l sphere of the resulting material reflected by 30 cm of water is about 93 cm. This j

corresponds to just over 900 gallons compared to the 600 gallon cake volume of the filter press. Therefore,0.29 Gd/100g U is sufficient to independently keep the filter

! press suf ficiently subcritical regardless of the U and H O concentration present in the 2

filter cake.

i e SPF Filtrate Tank I

i Criticality safety in the filtrate tank is maintained by controlling the enrichment (by sampling) of the uranium to a maximum of 4 wt% 235U and the U concentration in the filtrate to a maximum of 12 g Ult. The majority of the Gd remains in the solids.

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Summary of Accident Cond;tions i

The filtrate tank has an outside diameter of 11 feet 3 inches with a truncated cone bottom section. The height of the truncated cone is about 21 inches and the minor diameter is 6 inches. Assuming an 11 foot inside diameter, a conservative estimate of the tank volume in the cone shaped section is 1644.3 I and the area density of 345 kg U inside the filtrate tank is less than 3.6 kg U/ ft.2 AMENOWENT APPLCATION DATE; PAGE No :

January 7,1999 15-164 sPC-No 3330 947 @197S2)

Siemens Power Corporation - Nuclear Division eur2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 REV.

Based on SPF pilot test results, actual process conditions are expected to generate filtrates that are between 0.5 - 0.8 gU/t. The total U content in a 11,486 gallon (43,475 Il tank filled with 1.0 g U/t solution is about 43 kg. Although the uranium compounds in SPF filtrates are soluble, trace amounts of uranyl phosphate slowly form and settle as the filtrate cools. Although only a very small portion of the uranium in solution precipitates in this scenario, precipitation is of concern in any unfavorable l

geometry tank under concentration control. Therefore, the accidental addition of precipitating agents, such as LUR precipitating agents, to any unfavorable geometry tank under concentration control is a criticality safety concern.

i There are no precipitating agents routed directly to either the feed tank or the filtrate I

j tank. The bleach addition line to the feed tank is designed so that it is not possible to, l

j for example, accidentally connect the LUR precipitate line to the feed tank.

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! If all of the uranium from the feed tank were dissolved into the feed tank liquid and l

j then transferred into the filtrate tank, under the worst case conditions the filtrate tank could contain about 29,128 I (7695 gallons) of solution with 11.8 g U/t with the vast majority of U in solution and a small amount suspended as solids. A mixer in the filtrate tank and a recirculation pump are provided to mix and recirculate the filtrate in the tank and will keep any solids present in suspension.

l Assuming all 345 kg U in the tank is suspended solids, if the mixer and recirculation

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i pump f ail to keep any uranium particulates which may form suspended, the volume of the settled solids at 350 g U/t will be less than 986 t. This is less than 60% of the i

volume of the conc section of the tank and would resuit in sludge about 16.5 inches I

I deep. Given that the minimum critical slab depth for 400 g U/t UO -H O enriched to 4 2 2 wt.% 2asU is over 20 inches before k,n, exceeds 0.95 based solely on concentration,

! the sludge will occupy a subcritical depth.

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Based on the minimum critica! ccncentration and critical slab thickness data from j

l ARH-600, and the uniform settling of LUR precipitates, one can conclude criticality cannot be reached in the filtrate tank provided it is limited to 345 kg U (tank filled i

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with about 12 g U/l) cf uranium enriched to 4 wt.% asU.

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1 Although credit is ng.t taken for Gd, the pilot tests indicate that the filtrate will have l

j some small amounts of Gd present.

SPF Filters and Debris Screens The filters and debris screens used in SPF are sufficiently similar to those used in the LUR f acility that the discussion under LUR suffices for both.

AMENDMENT APPLCATION DATE:

PAGENo.

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Siemens Power Corporation - Nuclear Division EM F-2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70.1257 REV.

l 15.5.3 :.aaoon Uranium Recovery (LUR)

The LUR process has two feed sources. They are Lagoon 3 and the SPF. Lagoon liquids are paJmped into LUR from Lagoon 3 using the LUR feed pump. SPF sends filtrates to LUR using the filtrate pump located in the SPF portion of the building. A batch meter is used to set the volume of liquids to be pumped into the two LUR precipitator tanks each of which holds up to 6,000 gallons of liquids, if required, the solution pH can be adjusted during tank filling. Water may also be added to dilute the !

l lagoon solutions.

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j l Aqueous sodium hydrosulfite reductant is used to precipitate uranium in the LUR I

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precipitator tanks. The uranium is reduced to form a LUR precipitate which is arowed l

l to settle and crystallize.

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l After the precipitate settles, the supernate is decanted to Lagoon 4. The precipitates i

j can be do-watered either by going though a O.6 ft' filter press or by being washed and l 1

I decanting the supernate. The de-watered precipitate is sent to the ELO building for i

j purification via solvent extraction, i

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The major components of the LUR process are:

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1) Precipitator and precipitate wash tanks

2) Process filters l

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3) Process filter wash tanks i

i I 4) Filter press j

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5) Product transfe.r containers l

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6) Chemical addition system l

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15.5.3.1 LUR Criticality Safetv j Most of the major components in this process are unfavorable geometry vessels that j

I rely on uranium mass and concentration control. The large volume of material and low U concentrations dictate the use of unfavorable geometry vessels.

j LUR Precioitator and Precioitate Wash Tanks Criticality safety in these tanks is maintained by controlling the feed material U concentration such that less than a critical mass will be in the tanks even if a second process batch is accidentally added and precipitated before removing the material from the first process batch. Discussion of how Lagoon 3 and SPF U concentration s

i are controlled are in Section 15.5.2.

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l January 7,1999 15-166 sPC No 3330 Sc7 (Raio7/92) 4

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t Siemens Power Corporation - Nuclear Division eur.2 SPECIAL NUCLEAR MATERIAL LICENSE NC. SNM-1227, NRC DOCKET NO. 70-1257

REV, i

Summary of Accident Conditions The accident condition of largest impact in these tanks is exceeding the expected uranium mass in a process tank. The two general ways this can occur are to exceed I

the allowed feed U concentration or to process more than one batch before the precipitated solids are removed from the tanks.

I High U concentration in feed is discussed below.

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' The minimum critical U concentration for 5 wt% enriched UO -H O is 280-285 gU/l.

i 2 2 l The U density of settled solids will exceed this concentration; therefore, tight controls

on the feed concentration and removal of solids after each process batch before l

proceeding are required. Even if an unusually high 1 g U/t solution were used as a l

feed, a maximum of c out 23 kg of U could result from a single batch. Laboratory testing has shown ti-

fter centrifuging, these solids would not exceed 450 g U/t.

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The minimum critica. ass for 450 g U/t materialis approximately 74 kg U. The l

l precipitation tanks f s a nominal maximum volume of 6,000 gallons (22,700 liters).

Over three process be..ches of precipitated solids or a liquid feed concentration of 3 g l

U/t would be required to approach a critical mass of this material.

l Exceeding 74 kg in a single batch from feed materialis prevented by limiting feed materials to 1 g U/t. The current chemistry limits the solution concentration to about 200-500 ppm U.

i The feed material from the SPF will be determined to have less than 1 g U/l by at least ! l two independent means before a transfer to a precipitator tank is allowed, in addition, two independent organizations / separate persons must verify that the SPF filtrate

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I l contains less than 1 g U/l before unlocking the transfer line between the SPF filtrate l

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' tank and LUR. The transfer line is re-locked when the transfer is complete.

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If for some reason all of the U from the worst case U content in the SPF feed tank l

were dissolved into solution (345 kg U), the enrichment exceeded 4.0 wt. % 285U, the solution were to be transferred to the filtrate tank, the two lab analyses fail to detect g

the 12 g U/l solution, and this material were to be precipitated and allowed to settle, a i

l criticality would be possible. However, such a condition would require multiple failures.

Processing multiple batches in discussed below.

Getting a critical mass of U in these tanks from multiple batches is prevented by the following engineered and administrative actions:

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- The process is comrolled so that only one batch is allowed in each set of the unfavorable geometry precipitation and precipitate wash tanks.

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- The tanks are equipped with an automatic device to wash the tanks after each batch is processed.

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- An empty pipe detector, installed at the bottom of each tank, is interlocked to ensure the tank is empty before subsequent batches can be added.

- SOPS require the tanks to be inspect'ed and verified to be free of significant residue

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before the next batch may be processed.

l - The process piping is such that inadvertent transfers from one process line to the l

other process line are not possible.

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. Process Filters j

! Criticality safety in the 8 inch diameter by 30 inch long bag filters is maintained by

' safe geometry for up to 5 wt%

U enriched material. There are three pairs of filters 235 in the facility. The minimum spacing between filters in a pair is 22 inches, with the l'

next pair approximately 60 inches away, j

Summary of Accident Conditions I

The only accident conditions applicable to the process filters are spacing violations l

between the filters and moveable containers with fissile material and inadvertent loss of filter housing geometry. Assuming a maximum U density of 450 g U/1, approximately 155 liters is needed to contain a critical mass of material. To obtain this volume requires the combined volume of two completely full process filters; or i about 10 of the 4-gallon carboys that are used to transfer LUR precipitate to the ELO building for dissolution; or one process filter and five 4-gallon carboys. The contents of a single 4-gallon carboy are less than 8 kg of U.

i' The needed volume and mass to attain criticality would not be available even with

four simultaneous spacing violations. In addition, three edge-to-edge filters filled with a 79/21 volume-of-water to volume of-UO, ratio was evaluated. These filters were l

reflected on the bottom by 30 cm of concrete and on each on the remaining sides by l

l 30 cm of water. The resulting k,,, (including 20) was 0.934.

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The administrative controls on the process ensure that the maximum amount of uranium that could accumulate in all filters on a single process line will not exceed a safe mass. The loss of filter geometry could not result in a critical condition because the uranium mass available in a filter is not sufficient for criticality to occur. In addition, all the sumps in the process area are favorable geometry.

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LUR Process Filter Wash Tanks The filter wash tanks are unfavorable geometry tanks. The criticality analysis for these tanks in bounded by the analysis of the precipitator and precipitate wash tanks.

Summarv of Accident Conditions The only mechanism that could possibly result in more than a safe mass of materialin the filter wash tanks is for the contents of two completely filled filters with contents from multiple process batches to be placed into the wash tanks at one time. By the i

nature of a bag filter, it would be unusual for a filter to be completely full of U bearing solids. Howeve'r, the actual prevention of placing filters from both lines in a single l

wash tank or allowing the filters to be used for multiple batches without being washed is administrative. The administrative actions are:

I SOPS require the filters to be washed and the filter wash tanks to be verified to be free of significant residue before the next batch may be processed.

- A second operator verifies the filters were washed and the tanks are free from i

significant residue before adding the subsequent process batch.

An overflow line on the filter wash tanks provides a passive engineered feature to maintain a sub-critical solution depth in the tanks while filters are being washed. The overflow lines are verified to be unobstructed and free flowing prior to each use. The solids washed off of the filters are sent back into the process and the U recovered, i

• LUR Filter Press 1

Criticality safety in the filter press is maintained by a maximum enrichment of 4 wt%

i 22sU and by the press geometry. Enrichment of inputs directly from the lagoon are confirmed by monthly sampling. Those from SPC are confirmed by sampling the SPC i

feed tank.

l Summarv of Accident Conditions The potential accident conditions involving the LUR product filter press that could I,

result in unacceptable values of k,,, are:

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l - Exceeding 4.0 wt.% enriched material l

j Exceeding 1 gU/lin the precipitator vessel Accidentalleak of slurry into the cake catch container

- UOx buildup in the cake catch container.

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, AWENOMENT APPLCAh0N DATE:

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REV.

The controls required to prevent exceeding 4.0 v4.% enrichment are discussed in the discussion of the SPF process feed tank.

j The two feed sources to the precipitator tanks are directly from Lagoon 3 and from the SPF filtrate tank. Preventing more than a safe mass of precipitate in the precipitator tank was covered in the discussion on the precipitator and precipitate j

wash tanks. The expected U density of the LUR precipitate after pressing is less than

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450 g U/t. The geometry of the LUR product filter press is such that criticality is not possible in this filter press at any credible U density less than 3.0 g U/cc. U densities believed to be incredible, greater than 3.0 g U/cc, could exceed acceptab!s values of i

k,,,, but would still be subcritical. A critical volume of this material is approximately 155 liters. The volume of the filter cake secondary containment container is 1

I approximately 150 liters. To prevent unacceptable depths of slurries from collecting i

in this vessel, the two sides have cutouts that prevent exceeding a 3 inch depth of slurry. Administrative requirements ensure that the filter press geometry is maintained i

l and that the secondary containment container is cleaned after each batch is processed.

l LUR Product Transfer Containers j

Criticality safety with the product transfer containers,4 gallon carboys or buckets, is maintained by SPC's standard procedures for moderated materialin 5 gallon buckets -

l safe mass.

l Summarv of Accident Conditions Assuming a maximum U density of 450 g U/l in the LUR product, over 155 liters is needed to contain a critical mass (approximately 74 kg of U bearing material).

Approximately 10 of the 4-gallon carboys or 4-gallon buckets are required to obtain this volume. The maximum U content of a single transport container is approximately 8 kg U, which is significantly less than a safe batch (15.8 kg U assuming optimum i

I density, moderation, geometry and water reflection).

l-A scenario in which a criticality is possible with actual LUR product material with i

I density limited to 450 g U/l, is for the contents from about 20 containers to spillinto f a 155 liter spherical or near spherical volume where the spill can become a fully reflected and optimally moderated. Such a spill cannot occur because the product I would spread out into a slab on the floor and run into the sumps. The sumps in the LUR/SPF facility are all favorable geometry and will prevent criticality in the event of

product spills.

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Another scenario of interest is that of spacing violations. Assuming a maximum U density of 450 g U/l, over 155 liters is needed to contain a critical mass of material.

l As mentioned earlier, to obtain this volume requires the volume of two completely full process filters or about 10 of the 4-gallon containers that are used to transfer LUR precipitate to the ELO building for dissolution. The contents of a single 4-gallon l

container will be less than 8 kg of U. The mass needed for criticality would not be available even with four simultaneous spacing violations between 4-gallon containers and any one tank containing a safe mass.

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!e LUR Chemical Addition System l

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This makeup tank does not receive uranium bearing materials under normal conditions.

l Any occurrence of uranium in this vessel would be considered abnormal. The discussion of criticality safety for the SPF process feed tank bounds this process vessel.

l Summary of Accident Conditions I

Sodium hydrosulfite and other chemicals are discharged into the tops of the precipitation tanks. There is an air break between the chemical addition lines and the maximum tank level. This air break prevents uranium-bearing material from migrating l

back to the chemical supply tanks through the chemical addition lines. A uniform l

j uranium concentration as high as 140 g U/l still meets the SPC concentration control 2

I limit and an area density of 5.5 kg/ft is sub-critical by a factor of two.

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Process water is plumbed to severallocations at the bottoms of tanks to permit l

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flushing tr.ansfer lines. The process water supply comes from the city water main and l

is equipped with two back flow preventers. SOPS require the process water supply i

lines only to be connected while doing a system flush. This administrative l

l requirement aiong with the batch control on the process provide sufficlent protection to assure U cannot be transferred back to the city supply tanks.

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• System Interactions l

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} The major equipment components were modeled as cylinders of appropriate diameter I

l and length. They were modeled in their approximate locations. The unfavorable l

geometry tanks were each modeled as containing a hemispherical double batch at the l

l bottom of the tank. The region above this hemisphere was modeled as UO -H O with 2 2 a density of 3 g U/l. The filters are modeled as filled with optimally moderated UO -

2 H 0. The carboys are conservatively modeled as fi!Ied with 450 g Ull UO -H O and l '

j 2 2 2

located next to and between the filter wash tanks and a filter.

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auswowest appucation oats;

• act uo.;

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Results i

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The resulting maximum k,n from the interaction model of the LUR portion of the I

building is approximately O.72. This k,n is approximately the same as for a single fully reflected process filter. It is therefore confirmed that neutron interaction between system components is minimal. Because the process vessels in the SPF portion of the building are similar in size and separation and because k,n for the LUR j

model is so low, additional evaluation of neutron interactions are not needed.

i Interaction with Other Eculoment and Storace Arrays i

• l 4

Solutions from the LUR precipitation tanks are transferred to Lagoon 4. In the past l transfers were also made to Lagoon 3. This transfer line has been capped so transfers

. to Lagoon 3 are no longer possible without modifying the facility. Transfers to Lagoon j 3 from the precipitate wash tanks and filter wash tanks are still possible. However, I

the pH of the solutions transferred to Lagoon 3 are verified to be less than 8.0 (to 1

j prevent precipitation) before making the transfer. The makeup of the precipitating agents is limited to 50 10 lbs. which ensures that only relatively small amounts of U could be precipitated in the event of a catastrophic failure where all the precipitating agent for a single makeup is inadvertently transferred to Lagoon 3.

l Four potential concerns exist with material transferred to Lagoon 4.

These are:

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1. Incompatible solution chemistry results in Lagoon 4 solution depositing U bearing i

l solids in a localized area.

2. A buildup of solids transferred to Lagoon 4 into an unfavorable geometry over an extended period of time.

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3. The precipitator tanks overflow and the floor drain transfers Lagoon 3 solution to l

Lagoon 4.

4. The LUR product filter press f ails and sends concentrated solids to Lagoon 4.

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The U concentration in Lagoon 4 is currently between 20 and 50 ppm. The solutions in or routed to this lagoon have already been exposed to precipitating agents before l

they were transferred to the lagoon or have very low or nonexistent U concentrations.

I The addition of more precipitating agents will not result in forming an appreciable

! amount of uranium solids.

! Periodic sampling of Lagoon 4 solids will ensure any significant changes in the U and Gd content of these solids are detected wellin advance of approaching any unacceptable U concentrations. If needed, intervening actions will be taken to ensure that acceptable U concentrations are maintained.

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eur.2 SPECIAL NUCLEAR MATERIAL LICENSE NO. SNM-1227, NRC DOCKET NO. 70-1257 l

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REv.

The transfer of significant amounts of U bearing solids to Lagoon 4 is prevented by the design of the decant line, the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> settling time that is controlled by interlock, the presence of two in line bag filters to remove solids, and a turbidity monitor that is interlocked to stop the transfer if significant solids are detected. Additionally a l

gradual builduo will be detected by periodically sampling the solids in Lagoon 4 near the outfall of the LUR process.

The LUR filter press is routed so that the filtrate returns to the precipitation tanks.

l After the solids are removed from the filter press, the liquid remaining in the l

l precipitation tanks is either routed to Lagoon 4 via the precipitate wash tanks or j

l directly through a bag filter. Administrative checks are required to verify that the l

i j filtrate routed back to the precipitation tank is discharged before processing an l

l additional batch through the originating precipitation tank.

15.5.2.2 Radiation Protection i

Recovery of uranium from lagoon liquids and solids is performed in limited access 1

radiation controlled areas. Personnel entering the areas are required to wear radiation monitoring devices and protective clothing or equipment appropriate for the work to l

be performed. Personnel are required to survey themselves prior to exiting the controlled area. All personnel also receive initial and yearly refresher training on radiation protection principles and requirements. Equipment leaving the controlled area must be surveyed and released.

l Urine sample analyses and lung counts are periodically performed for personnel who I

i i work in the controlled access area. The frequency of such tests is described in i

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- Chapter 3.

l j Routine surveys are performed and houseireeping practices are enferced to minimize

' surface and airborne contamination in the processing areas. Air is continuously i

j sampled and periodically analyzed to identify airborne contamination.

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. Uranium bearing material is present in the system as uranium oxides, nitrates, and l

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sulfates.

Personnel exposure to this material is limited during normal operations.

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! Personnel contact with respirable uranium is minimal because the uranium in this I system is a liquid or a slurry which are not prone to become airborne, f

15.5.2.3 Fire Protection The LUR/SPF is rated as noncombustible. Fire loading is kept to a minimum through periodic inspections. Fire extinguishers, alarm pull boxes and heat detectors are strategically placed throughout the f acility.

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e A wet pipe fire sprinkling system is installed in the LUR/SPF processing area.

Additionally plant personnel are trained in the correct use of the fire extinguishers which are located throughout the plant site.

All fire alarms originating in the LUR/SPF building are relayed to the central guard station and have a direct connection to the City of Richland Fire Department.

15.5.2.4 Environmental Safety l

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! Materials processed in the LUR/SPF are primarily confined within containers and 1

piping. The areas are serviced by a "once-through" HVAC system that is continuously l j

i monitored for radioactive contamination. The exhaust systems for the area are double 1

.}

I HEPA filtered and have deluge systems to protect the final filters from fire.

i 15.5.2.5 Chemical Safety I

Chemical safety in the LUR and SPF processes is ensured through the use of SOPS i

which govern the handling, storage, and use of chemicals. Appropriate equipment, such as jack trucks, are used to place chemical drums or tanks on secondary containment basins located within approved storage buildings. Protective equipment required by SOP is worn when handling the chemicals manually. Chemical compatible materials are used for piping and pumps and process vessels which hold chemicals l

and are equipped with vessel ventilation systems. Air sampling is performed to ensure !

that airborne vapors / mists /particulates are below OSHA limits.

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