COMMUNITY REUSE ORGANIZATION OF EAST TENNESSEE

                                    SUBLEASE

         THIS  SUBLEASE,  entered  into  this  25 day  of  March,  1999  between
COMMUNITY  REUSE   ORGANIZATION  OF  EAST  TENNESSEE,   a  Tennessee   nonprofit
corporation hereinafter referred to as "CROET," and THERAGENICS  CORPORATION,  a
Delaware  corporation,  hereinafter referred to as the "Sublessee," provides for
the use and development by the Sublessee of  Government-owned  real and personal
property held by CROET  pursuant to two Leases from the United States of America
acting by and  through  the  Department  of Energy,  hereinafter  referred to as
"DOE." The  DOE-CROET  leases are (1) a lease  entered into January 16, 1996, as
amended by  Supplemental  Agreement of Outgrant No. 1 effective  April 28, 1998,
and  Supplemental  Agreement  of  Outgrant  No. 2 effective  January  13,  1999,
Supplemental  Agreement  of Outgrant  No. 3 effective  February  23,  1999,  and
Supplemental  Agreement of Outgrant No. 4 effective  February 25, 1999 for a DOE
owned  track of  undeveloped  land near DOE's  East  Tennessee  Technology  Park
("ETTP") to be developed by CROET through  arrangements with commercial firms or
public entities,  said lease being  hereinafter  referred to as the "Land Lease"
and, (2)  Department of Energy Lease entered into March 22, 1999,  for the lease
of DOE owned equipment consisting of the Plasma Separation Process ("PSP") to be
used  for  producing  isotopes,  said  lease  hereinafter  referred  to  as  the
"Equipment  Lease."  The Land  Lease and the  Equipment  Lease are  collectively
hereinafter  referred  to as  "Leases."  The  parcel  of land  subleased  to the
Sublessee under this Sublease  consists of approximately 21 acres, is identified
as parcel  HOC-001 on the drawing  attached  hereto as Appendix "A," and will be
referred to throughout this Sublease as the "Premises." In the event  Sublessee,
at its expense, obtains a current survey of the Premises, a legal description of
the Premises  prepared from such survey may, by amendment  executed by CROET and
Sublessee, be incorporated herein.

         CROET does hereby  sublease to  Sublessee,  and  Sublessee  does hereby
sublease from CROET, the Premises and the PSP.

         This Sublease is granted subject to the following terms and conditions:

1.       CROET AUTHORITY TO SUBLEASE. This Sublease is made by CROET pursuant to
         Condition  No. 7 of the Land Lease and Condition No. 6 of the Equipment
         Lease.  So long as Sublessee  makes  payments and performs and complies
         with the other covenants,  terms, and conditions set forth herein to be
         performed or complied with by Sublessee, CROET does hereby covenant and
         agree that  Sublessee may peacefully  hold,  enjoy and use the Premises
         and  the  PSP  during  the  term  hereof   without  any   hindrance  or
         interference.

2.       TERM.

         The term of this  Sublease  shall be May 1, 1999,  and ending April 30,
         2029; provided,  however,  that Sublessee  acknowledges that the Leases
         and this Sublease are terminable by DOE under the provisions  contained
         in  Condition  No.  4 of the  Land  Lease  and  Condition  No. 3 of the
         Equipment Lease.

3.       TERMINATION BY DOE OR CROET.

         (a)      The Sublessee  acknowledges  that DOE may terminate the Leases
                  and this Sublease at any time as provided in Condition No. 4 
                  of the Land Lease and Condition No. 3 of the Equipment Lease; 
                  provided however, in the event of such  termination by DOE, 
                  the  Sublessee  shall be entitled to a refund of any rent paid
                  under paragraph  4(a) below for any period after the date of 
                  termination.  Additionally, in the event DOE terminates the 
                  Land Lease and this Sublease due to national emergency or in 
                  the interest of national defense, CROET acknowledges 
                  and agrees that Sublessee shall be entitled to the 
                  compensation  set forth in Condition No. 41 of the Land Lease 
                  and CROET will assist Sublessee in obtaining such 
                  compensation; provided that this shall not 
                  be construed as imposing  liability on CROET to pay such 
                  compensation if DOE does not do so.

         (b)      CROET may terminate this Sublease at any time by giving 
                  ninety (90) days written notice by the authorized 
                  representative to the Sublessee under any of the following  
                  circumstances:  If the Sublessee fails to  substantially  
                  perform or comply with any of the terms and  conditions 
                  of this  Sublease and continues and persists therein for 
                  ten (10) days after notice thereof in writing by CROET; 
                  provided,  however, if such default is not reasonably capable 
                  of cure within such ten (10) day period,  CROET shall not be 
                  entitled to terminate this Sublease if Sublessee promptly 
                  undertakes to cure such default and diligently pursues such 
                  cure. In the event of such termination,  CROET shall be 
                  entitled to recover from the  Sublessee  the costs incurred by
                  CROET in performing  any obligation  on the part of the 
                  Sublessee to be performed  under the terms of this Sublease 
                  for any period prior to the date of  termination or for costs 
                  incurred by CROET as a result of matters arising after the 
                  date of termination but which resulted from Sublessee's  
                  actions prior to the date of termination.

         (c)      The Sublessee   agrees  to  engage  an   architectural   and
                  engineering firm to design the improvements  Sublessee desires
                  to construct on the Premises  (the  "Facility")  within ninety
                  (90)  days  from  the  date of  this  Sublease.  In the  event
                  Sublessee  does not use  reasonable  efforts to  complete  the
                  Facility  on or before the later of (i) one (1) year after the
                  date of this Sublease, or (ii) the date upon which the PSP and
                  all necessary  component  parts  (including any new parts that
                  need to be ordered or fabricated) are ready to be installed in
                  the  Facility,  CROET  shall have the right to  terminate  the
                  Sublease on not less than thirty (30) days  written  notice to
                  Sublessee  unless Sublessee  promptly  commences to attempt to
                  develop  the  Premises  on or before  thirty  (30) days  after
                  receipt of such notice of default.

         (d)      CROET may terminate  this Sublease in the event that Sublessee
                  fails to obtain all the required  governmental  and regulatory
                  authority,  licenses,  permits,  approval and consents for the
                  development,  use and operation of the  Facility,  the PSP and
                  any  other  equipment  required  for  use in  connection  with
                  Sublessee's  business  operations on the  Premises,  provided,
                  that this shall not be construed as requiring the Sublessee to
                  operate  the PSP on the  Premises  or to  engage  in  activity
                  requiring any particular license.

         (e)      The Sublessee  shall also pay to CROET on demand any sum which
                  CROET is  obligated  to pay to DOE by reason  of  expenditures
                  after  the  expiration,  revocation,  or  termination  of this
                  Sublease in restoring the Premises to the  condition  required
                  by Condition  No. 33 of the Land Lease and Condition No. 23 of
                  the Equipment Lease; provided,  however, this shall not in any
                  manner  relieve  CROET or DOE  from  any of  their  respective
                  liabilities,  to the  extent  the  cause  of such  restoration
                  resulted, in whole or in part, from their acts or omissions.

In any of the above events, the provisions of Condition No. 33 of the Land Lease
and Condition and 23 of the Equipment Lease shall apply to the Premises.

4.       RENT.

         (a)     Land Rent. The Sublessee shall pay to CROET land rental for the
                 premises  according to the following terms:

                 (1)    $  [Confidential  Treatment  Requested]  per month until
                        January 1, 2000.
                 (2)    $ [Confidential Treatment Requested] per annum 
                        [Confidential Treatment Requested] after January 1, 
                        2000, and every year thereafter, to be paid in equal 
                        monthly amounts on the first day of each calendar month;
                        [Confidential Treatment Requested]. The land rental 
                        shall be adjusted as set forth in this paragraph 4(a).  
                        Such rent shall be prorated for any portion of the term 
                        which is not a full calendar month.

                  On January 1, 2005 and each fifth (5th) anniversary thereafter
                  during the term of this  Sublease,  the land  rental  shall be
                  increased by an amount equal to the product of: (i) the amount
                  of  land  rental  set  forth  in  paragraph  4(a)(2)  of  this
                  Sublease,  multiplied by (ii) the fraction whose  numerator is
                  the  Consumer  Price Index (as  hereinafter  defined)  for the
                  calendar  month  just  ended  and  whose  denominator  is  the
                  Consumer Price Index for the calendar month January, 2000. The
                  term  "Consumer  Price  Index" as used  herein  shall mean the
                  Consumer  Price  Index  for All Urban  Consumer  (1982-84=100)
                  specified  for All Items,  U.S. City Average and issued by the
                  Bureau of Labor Statistics of the United States  Department of
                  Labor.  In the event the Consumer Price Index shall  hereafter
                  be  converted  to  a  different  standard  reference  base  or
                  otherwise   revised,   CROET  shall   designate  a  comparable
                  procedure for adjustment of land rent.

         (b)      Equipment  Rent.  The Sublessee  shall pay to CROET  equipment
                  rental, for the PSP, according to the following terms:

                  (1)   $ [Confidential Treatment Requested] per month until the
                        equipment becomes operational.
                  (2)   $ [Confidential  Treatment Requested] per month
                        after the equipment becomes operational,  whether or not
                        it continues in operation.

         (c)      Utilities and Services. The Sublessee shall be responsible for
                  paying the charges for  utilities and services DOE may provide
                  to the Premises under Condition No. 5(b) of the Land Lease, as
                  such  charges are  determined  and  charged by DOE;  provided,
                  however, Sublessee shall only be required to pay for utilities
                  and services actually being used or consumed by Sublessee. The
                  method of payment to DOE shall be  determined by CROET and the
                  Sublessee.  Sublessee  shall be responsible for paying for all
                  utilities  and  services  actually  being used or  consumed by
                  Sublessee  which are  provided  by any  entity  other than DOE
                  under terms and  conditions  to be arranged by Sublessee  with
                  that entity.

         (d)      Additional  Consideration.  The Sublessee shall be responsible
                  for the expense of  maintenance,  operations,  alterations and
                  repairs to the Premises  for the entire term of the  Sublease,
                  and shall pay to the taxing  authority  any taxes  levied as a
                  result of this  Sublease  excluding  any taxes levied on CROET
                  because of its separate status as a corporation.  CROET agrees
                  to  reasonably   cooperate   with  Sublessee  in  seeking  tax
                  relief/abatement  measures  with  applicable  city and  county
                  governmental authorities with respect to the Premises, the PSP
                  and the Sublease.

5.       IMPROVEMENTS  TO THE  PREMISES.  
         ------------------------------
         Consistent with various  requirements  contained in the Land Lease, and
         accepted by the Sublessee  under  Condition No. 9 below,  the Sublessee
         may, at its expense, make such improvements on the Premises,  including
         erecting  structures and making tie-ins to utilities,  as are necessary
         to conduct Sublessee's  business.  Title to all such improvements shall
         be vested in the Sublessee  until the Sublease is terminated or expires
         of its own terms, at which time the status of such improvements will be
         controlled by Condition No. 17 of the Land Lease.  The foregoing  shall
         not in any  manner  restrict  or impair the right of  Sublessee,  if it
         elects,  to remove its trade  fixtures and personal  property  from the
         Premises at the end of the term of this Sublease,  but Sublessee  shall
         be responsible for any damage to the Premises caused by such removal.

6.       EMPLOYMENT.
         ----------

         Consistent with applicable laws, rules, regulations and ordinances, and
         the various requirements contained in the Land Lease, the Sublessee, in
         hiring  workers  for work on the  Premises,  shall give  preference  to
         workers  formerly  employed  at  DOE  installations  on the  Oak  Ridge
         reservation,  all other things being equal among prospective employees.
         The Sublessee shall report to CROET in writing  annually or upon demand
         by CROET the number of employees  working on the  premises  and, to the
         extent  the  Sublessee  has  actual   knowledge  based  on  information
         furnished  to it by CROET or through  arrangements  made by CROET,  the
         number   among  them  who  are   workers   formerly   employed  at  DOE
         installations on the Oak Ridge  reservations.  The Sublessee commits to
         use its best efforts to employ for work on the  premises the  following
         numbers of full-time employees ("FTEs"):

                           Year 1                 * FTEs
                           Year 2                 * FTEs
                           Year 3                 * FTEs
                           Year 4                 * FTEs
                           Year 5                 * FTEs
                           Years Beyond 5         * FTEs
                                             [*Confidential Treatment Requested]

         The sole remedy for failure to achieve, or use Sublessee's best efforts
         to achieve, these employment levels on the premises shall result in the
         Sublessee paying an additional  [Confidential  Treatment  Requested] in
         land rent and equipment  rent for the year involved,  unless  Sublessee
         can demonstrate that business factors beyond its control were the cause
         for not meeting the employment level. Should the Sublessee exceed those
         employment  levels by  [Confidential  Treatment  Requested] or more the
         sublessee  shall pay  [Confidential  Treatment  Requested] less in land
         rent and equipment rent for the years involved.

7.       AUTHORIZED  REPRESENTATIVES. CROET'S representative concerning  the  
         ---------------------------
         provisions of this Sublease  shall be Lawrence  Young, Community Reuse 
         Organization  of East  Tennessee,  107 Lea Way, P.O. Box 2110, Oak 
         Ridge,  Tennessee,  37830,  Tel. No. (423) 482-1336.  The  Sublessee's
         representative shall be Christine Jacobs, Theragenics Corporation, 5325
         Oakbrook  Parkway, Norcross,  Georgia,  30093, Tel. No. (770)-271-0233.
         Any changes in the  designated  representative  or their  respective
         addresses shall be given in writing to the other.

8.       NOTICE.  No  notice,  order,  direction,  determination,   requirement,
         ------
         consent, or approval under this Sublease shall be of any effect, within
         the  restrictions  of this Sublease,  unless provided in writing to the
         authorized representative at the address set forth in paragraph 7 above
         by personal  delivery (or reputable  overnight  courier  service) or by
         certified mail, return receipt requested,  postage prepaid. All notices
         shall be  effective  upon  receipt  at the proper  address.  Refusal to
         accept delivery shall be deemed receipt.

9.       OBLIGATIONS  OF THE  SUBLESSEE.  The Land  Lease and  Equipment  Lease
         ------------------------------
         retain for DOE certain rights and imposes various obligations on CROET.
         Sublessee's  obligations  under this  Sublease  shall be subject to the
         terms and conditions  imposed on CROET under the Leases during the term
         of this Sublease,  and for any period beyond the term, during which the
         rights of DOE and  obligations  of CROET are affected by the failure of
         the  Sublessee  to  recognize,  abide by,  or  fulfill  obligations  of
         Sublessee  under this  Sublease.  Sublease  assumes the  obligations of
         CROET under the Land Lease but only with respect to the  Premises  (and
         not with respect to any other premises  included in the Land Lease) and
         only as to such obligations arising during the term of this Sublease or
         as a result of the performance of the Sublessee.  The Sublessee  agrees
         to hold CROET  harmless  for any failure on its part,  or those  acting
         through it, to recognize,  abide by, or fulfill the obligations assumed
         by  Sublessee  under this  Sublease.  The  assumption  by  Sublessee of
         obligations  under  this  Sublease  is not  intended  to,  nor  does it
         constitute,  an  assignment  by CROET to the Sublessee of the Leases or
         any portion  thereof.  CROET does hereby  indemnify and hold  Sublessee
         harmless  as a result of  CROET's  failure  to  recognize,  abide by or
         fulfill the  obligations of CROET under the Leases,  to the extent such
         obligations  are not  obligations in the Leases which the Sublessee has
         assumed under this Sublease.

         CROET  acknowledges  that Sublesse's  sole  obligations and liabilities
         with respect to loss, damage or destruction of the PSP are as set forth
         in Condition No. 10 of the Equipment Lease.

         In addition,  and without  regard to the  obligations  contained in the
         Leases to which the  Sublessee is obligated,  the  Sublessee  agrees to
         hold CROET  harmless  against any  liabilities of CROET which may arise
         during the term of this Sublease arising out of Sublessee's  negligence
         or wilful  misconduct.  Nothing in this Sublease shall in any manner be
         construed to relieve or release  CROET from any  liability  for its own
         negligence or wilful misconduct.

10.      INSURANCE. In addition to the requirements of the Leases, all insurance
         required of the Sublessee  shall be for the  protection of CROET,  DOE,
         and the Sublessee  against their  respective  risks and liabilities and
         shall be in such form,  for such period of time, and with such insurers
         as CROET and DOE may reasonably require. Insurance of the types, and in
         the amounts, shall include at least the following:

               General Liability                              $*
               Automobile, if applicable to Sublessee         $*
               Workman's Compensation                        (statutory amount)
                                            [*Confidential Treatment Requested]

         A  certificate  of  insurance  or a  certified  copy of each  policy of
         insurance  shall be  furnished  to CROET and DOE's  Realty  Officer and
         DOE's  Account  Executive  prior to use of the Premises or the PSP. The
         Sublessee  agrees  that not less than  thirty  (30)  days  prior to the
         expiration of any insurance required by this Sublease,  it will furnish
         to CROET  and  DOE's  Realty  Officer  and DOE's  Account  Executive  a
         certificate  of insurance or a certified copy of each renewal policy to
         cover the same risks.  The Sublessee shall provide evidence of adequate
         insurance  coverage for Bodily Injury and Property Damage.  Each policy
         of insurance  against loss or damage to DOE's  property  shall name the
         Sublessee,  CROET,  and DOE as the  insured  and  shall  contain a loss
         payable clause reading substantially as follows:

                  "Loss,  if any, under this policy shall be adjusted with (name
                  of Sublessee) and the proceeds, at the direction of DOE, shall
                  be payable to (name of  Sublessee),  and  proceeds not paid to
                  (name of  Sublessee)  shall be payable to the Treasurer of the
                  United States of America."

        Additionally,  each policy of  insurance  shall  contain an  endorsement
        reading substantially as follows:

                  "The  insurer  waives  any right of  subrogation  against  the
                  United  States of America  which  might arise by reason of any
                  payment made under this policy."

         The  Sublessee is  encouraged to carry  business  disruption  insurance
         sufficient to cover losses due to interruption  of business  activities
         under this Sublease  caused by events of every kind.  CROET will not be
         liable for any such losses,  whether or not the Sublessee  carries such
         insurance,  and the  Sublessee  agrees  to waive  any  claims  it might
         otherwise have against CROET for such losses;  provided,  however, this
         shall  not  in  any  manner  relieve  CROET  from  and  liabilities  or
         obligations arising out of CROET's negligence or wilful misconduct.

11.      DOE - CROET LAND LEASE  OBLIGATIONS.  CROET hereby covenants and agrees
         -----------------------------------
         to comply with all  obligations  of the tenant under the Land Lease and
         the Equipment Lease; provided, however, to the extent that Sublessee is
         obligated  under this  Sublease for any such  obligations,  CROET shall
         have no responsibility therefor. In the event CROET receives any notice
         of any default,  event of default, or non-compliance with the terms and
         conditions  of the Land  Lease  or the  Equipment  Lease,  and in DOE's
         judgment CROET is not taking adequate steps to cure the default,  CROET
         shall promptly advise Sublessee of such matters. CROET hereby grants to
         Sublessee the right (but not the obligation, unless otherwise set forth
         in  this   Sublease)  to  cure  any   default,   event  of  default  or
         non-compliance  with the Land Lease or the Equipment Lease. Any amounts
         expended by Sublessee in a  successful  cure may be offset  against any
         amounts due under this Sublessee, but only to the extent that Sublessee
         is not obligated under the terms of this Sublease for such  performance
         under the Land Lease or the Equipment Lease.

12.      EMINENT  DOMAIN.  If all or any part of the Premises shall be 
         ---------------
         appropriated  or condemned by any public or  quasi-public  authority in
         the exercise of its right of condemnation or eminent domain, both CROET
         and  Sublessee  shall have the right to  prosecute a claim for an award
         and to share in the  proceeds  of any and all  awards  based upon their
         respective  interests as hereafter set forth. If all the Premises shall
         be appropriated or condemned,  or so much thereof that Sublessee cannot
         reasonably  continue  the  operation  of  its  business  thereon,  this
         Sublease  shall  terminate  as of the  time  when  possession  shall be
         required by such public or  quasi-public  authority.  In the event that
         this  Subleases  shall not terminate  after any part of the Premises is
         taken or  condemned,  there shall be a reduction in rental equal to the
         percentage  to the  ground  area of the  Premises  which  is  taken  or
         condemned.  CROET shall be entitled to receive  that portion of any and
         all awards  necessary  to  compensate  it for the present  value of the
         rents  which it would have  received  in the future and for the present
         value of its reversionary interest, and notwithstanding the termination
         of this  Sublease,  Sublessee  shall be entitled to that portion of any
         and  all  awards  necessary  to  compensate  it for  the  value  of its
         improvements to the Premises, the value of its leasehold estate and the
         damages  which  it may  sustain  as a  result  of  termination  of this
         Sublease prior to the end of the Sublease  term,  including any renewal
         terms.

13.      LANDLORD'S  ACCESS TO  PREMISES.  Notwithstanding anything to the 
         -------------------------------
         contrary in this Sublease,  entry to the Premises by CROET will only be
         permitted when accompanied by Sublessee's  authorized escort, except as
         hereinafter provided. It is recognized by both CROET and Sublessee that
         Sublessee will be performing research on, and manufacturing,  drugs for
         human   consumption   under   regulations  and  licenses  from  various
         governmental agencies,  including, without limitation, the Federal Drug
         Administration  ("FDA").  Sublessee is responsible to such governmental
         agencies,  including,  without limitation, the FDA, for compliance with
         all applicable  laws,  rules,  regulations  and  ordinances  (including
         protection of materials in work areas from unauthorized  alterations or
         access),  whose  object it is to protect  the public  from  adulterated
         contaminated  or  otherwise   uncontrolled   and  potentially   harmful
         products. CROET acknowledges it is not competent to judge the impact of
         its entry of the Premises on the relationship between Sublessee and the
         applicable regulatory authorities and potential impact on public health
         and safety.

         CROET hereby agrees,  except as hereinafter  expressly  provided,  that
         CROET shall provide  Sublessee with one (1) business day advance notice
         of any desire by CROET, or its authorized  agents or  representative to
         enter the  Premises.  All  entries on the  Premises  must  comply  with
         applicable laws, rules, regulations and ordinances (collectively called
         the  "Regulations").  Upon request,  Sublessee  will provide CROET with
         necessary information  concerning the Regulations.  Except as expressly
         hereinafter  provided,  all  entries  shall  be  with  an  escort  from
         Sublessee or its representatives and shall be subject to all reasonable
         safety procedures and guidelines as may be prescribed by Sublessee.

         In the case of  emergencies,  CROET may enter the Premises  unannounced
         and  unescorted;  provided,  however,  CROET agrees to  cooperate  with
         Sublessee  in complying  with all  reporting  requirements  pursuant to
         applicable Regulations.

         It is further  recognized  by CROET and  Sublessee  that  Sublessee  is
         engaged in commerce utilizing proprietary and confidential information,
         processes  and  procedures.  CROET  agrees that any  written  materials
         located on or in the Premises  obtained during any inspection or access
         to the  Premises  by  CROET  (or its  agents  or  employees)  shall  be
         confidential  except for written  materials  delivered to CROET, or its
         agents or employees, by Sublessee or its employees;  provided, however,
         this shall not affect CROET's  ability to obtain  information to assess
         Sublessee's  compliance  with the terms and conditions of this Sublease
         with respect to  Sublessee's  use,  operation  and  maintenance  of the
         Premises,  and further provided that CROET may divulge such information
         to its agents, employees,  contractors,  attorneys, prospective lenders
         and purchasers and to DOE.

14. OPTION TO SUBLEASE ADJOINING LAND AND RIGHT OF FIRST REFUSAL.

   (a)            During the Option Period (as defined in paragraph  14(b)),  
                  CROET hereby grants unto Sublessee the  non-exclusive right 
                  and option to  sublease  the  remainder  of Site 3 of  Parcel 
                  ED-1  (containing  approximately  [Confidential  Treatment
                  Requested]  acres) and identified as the  "Adjoining Property"
                  on Appendix "A"  attached  hereto (the  "Adjoining Property"),
                  on the  same  terms  and  conditions  as  contained  in this  
                  Sublease  (with  the land  rental  being $ [Confidential  
                  Treatment  Requested]  per acre per year, as adjusted by the 
                  Consumer Price Index every five (5) years from the date of 
                  this  Sublease) for the remaining  term set forth in this  
                  Sublease.  Sublessee  shall give CROET no less than thirty 
                  (30) days  advance  written  notice of the  exercise of this  
                  option.  This option  shall  terminate simultaneously  with 
                  the right of first refusal set forth below. If said first 
                  refusal right is triggered,  the terms of the first refusal 
                  right shall control in lieu of the non-exclusive option terms 
                  hereinbefore set forth provided a sublease of the Adjoining  
                  Property is consummated  to the third-party offeree or to 
                  Sublessee  under the following paragraph.

                  In the event CROET receives a bona fide written offer from any
                  third party to sublet the  Adjoining  Property (or any portion
                  thereof  or any tract of which  the  Adjoining  Property  is a
                  part)  during the Option  Period,  CROET has  granted and does
                  hereby  grant the  right,  on a right of first  refusal  basis
                  described  hereinafter,   to  Sublessee,  its  successors  and
                  assigns,  at the election of Sublessee  or its  successors  or
                  assigns,  to sublet the Adjoining Property at the price and on
                  the terms and conditions contained in the written offer except
                  the term of any sublease  shall not extend  beyond the term of
                  this Sublease and further  except for the time within which to
                  close the transaction. CROET shall give notice to Sublessee of
                  the written offer,  including  delivery to Sublessee of a true
                  and exact  copy of the  written  offer,  and  allow  Sublessee
                  thirty (30)  calendar  days  subsequent  to the notice  within
                  which  Sublessee may elect to sublet from CROET.  In the event
                  Sublessee  so  elects  to  sublet  by  giving  notice  of such
                  election to CROET  within the thirty  (30) day  period,  CROET
                  shall sublet the Adjoining  Property to Sublessee at the price
                  and on the same terms and  conditions  as are contained in the
                  written offer,  except that (i) Sublessee shall also reimburse
                  CROET for its reasonable  marketing  expenses  incurred in its
                  effort to sublease  the  Premises  to the third party  offeree
                  which  triggered  this  right of first  refusal,  and (ii) the
                  closing of the  transaction  shall be held  within  sixty (60)
                  calendar days following the expiration of the aforesaid 30-day
                  period.  Should Sublessee by written notice to CROET elect not
                  to exercise  the right to sublet or should  Sublessee  fail to
                  notify  CROET of its election to sublet  within the  aforesaid
                  30-day  period,  then in either of such events  CROET shall be
                  free to consummate  the sublease of the Adjoining  Property to
                  the third party  submitting the written  offer,  provided that
                  the  sublease  is closed  and on the same  material  terms and
                  conditions as are contained in the written offer,  without any
                  substantive  modification  thereto,  except  that the  closing
                  thereof  may  occur on or  before  the  thirtieth  (30th)  day
                  subsequent  to the closing  deadline  set forth in the written
                  offer.   Should  any  such  sublease  not  be  consummated  as
                  aforesaid,  CROET  shall,  in  the  event  CROET  subsequently
                  receives any modified or new bona fide written  offer from any
                  third party to sublet the Adjoining Property, again follow the
                  provisions of this paragraph 14 requiring  notice to Sublessee
                  and   opportunity   for  Sublessee  to  sublet  the  Adjoining
                  Property.  No restriction  on CROET's  ability to sublease the
                  Adjoining Property shall apply to any period subsequent to the
                  Option Period. CROET shall not be obligated to offer to sublet
                  the  Adjoining  Property,  and CROET shall not be obligated to
                  disclose  to  Sublessee  any  offer to  sublet  the  Adjoining
                  Property which CROET receives which CROET,  in its discretion,
                  does  not  intend  to  accept.  The  aforesaid  right of first
                  refusal  in  favor  of  Sublessee  is a  material  part of the
                  consideration for this Sublease and shall and does hereby vest
                  in  Sublessee,   its  successors  and  assigns,   immediately.
                  Sublessee  may not  exercise  its right to sublet  pursuant to
                  this  paragraph  14 if at the time of the  attempted  exercise
                  Sublessee is in default (for which any applicable  cure period
                  has expired without cure) under the terms of this Sublease.

   (b)            The non-exclusive option and right of first refusal set forth
                  in paragraph  14(a) shall be in effect,  at no additional cost
                  or charge to Sublessee,  from the date of this Sublease  until
                  January 1, 2002,  as may be  extended by mutual  agreement  of
                  CROET and Sublessee for such  consideration as mutually agreed
                  by said parties. This three-year period, as may be extended as
                  aforesaid, is herein called the "Option Period."

   (c)            In the event the Sublessee exercises the option granted 
                  herein,  or  successfully  invokes its right of first refusal 
                  granted herein,  CROET may terminate  the rights so granted or
                  invoked and all rights with respect to the Adjoining  Property
                  shall revert to CROET and this Sublease  shall be terminated  
                  solely as to the Adjoining  Property  unless (i) within
                  ninety (90) days from the date of the  exercise of the option 
                  or  successful  invoking of the right of first  refusal
                  the Sublessee agrees to engage an  architectural and 
                  engineering firm to design a facility to be constructed on the
                  Adjoining Property that is consistent with the permitted uses 
                  of the Adjoining  Property,  and (ii) the employment on
                  the Premises and the Adjoining Property,  in the aggregate,  
                  \shall be at least [Confidential  Treatment Requested] of
                  the employment  figures described in paragraph 6 herein,  and 
                  (iii) the Sublessee uses reasonable efforts to complete
                  the  facility on the  Adjoining Property on or before one year
                  after the  exercising  of the option or  successfully
                  invoking its right of first  refusal.  This right of CROET to 
                  terminate  the  Sublessee's  rights and interest in the
                  Adjoining  Property shall be given to the Sublessee by written
                  notice thirty (30) days prior to termination,  and the
                  termination  shall not take effect if the Sublessee promptly 
                  commences to develop the  Adjoining  Property  within
                  thirty (30) days of receiving this notice.

15.      LEASEHOLD  MORTGAGES/DEEDS  OF TRUST.  Sublessee  is hereby  given the 
         ------------------------------------
         right by CROET in addition to any other rights herein granted,  without
         CROET's prior written consent, to mortgage,  or to grant deeds of trust
         in and to  (collectively  "mortgage"),  Sublessee's  interests  in this
         Sublease,  and assign  this  Sublease as  security  for a Mortgage  (as
         hereinafter  defined) upon the condition that all rights acquired under
         such  Mortgage  shall be  subject to all of the  terms,  covenants  and
         conditions of this  Sublease,  and to all rights and interests of CROET
         herein,  none of which terms,  covenants or  conditions  is or shall be
         waived  by CROET by  reason  of the  right  given so to  mortgage  such
         interest in this  Sublease,  except as expressly  provided  herein.  If
         Sublessee  (including,  but not limited to, any sublessee of Sublessee,
         but only with Sublessee's prior consent) shall mortgage this leasehold,
         or any part or parts  thereof,  and if the  Mortgagee  (as  hereinafter
         defined)  shall  send to CROET a true  copy  thereof,  together  with a
         notice  specifying  the  name  and  address  of the  Mortgagee  and the
         pertinent  recording date with respect to such  Mortgage,  CROET agrees
         that as long as any such Mortgage shall remain unsatisfied of record or
         until a notice of satisfaction is given by the Mortgagee to CROET,  the
         following provisions shall apply:
        (i)       There shall be no  cancellation,  surrender or modification of
                  this Sublease by joint action of CROET and  Sublessee  without
                  the prior consent of the Mortgagee;
        (ii)      CROET  shall,  upon  serving  Sublessee  with  any  notice  of
                  default,  simultaneously  serve a copy of such notice upon the
                  Mortgagee. The Mortgagee shall thereupon have the same period,
                  after service of such notice upon it, to remedy or cause to be
                  remedied  the defaults  complained  of, and CROET shall accept
                  such performance by or at the instigation of such Mortgagee as
                  if the same had been done by Sublessee.  Mortgagee  shall give
                  notice to CROET in the  event  Mortgagee  elects to  undertake
                  remedial action which involves Mortgagee taking possession and
                  control of the Premises  and/or the PSP to cure any default by
                  Sublessee under this Sublease.
        (iii)     CROET  agrees  that in the  event of the  termination  of this
                  Sublease by reason of any default by Sublessee  other than for
                  nonpayment of basic rent,  CROET will, upon written request of
                  Mortgagee,  enter into a new sublease of the Premises with the
                  Mortgagee or its  nominee(s),  for the  remainder of the term,
                  effective  as of the  date of such  termination,  at the  same
                  basic rent and upon the terms,  covenants  and  conditions  as
                  herein  contained  and subject only to the same  conditions of
                  title  as  this  Sublease  is  subject  to on the  date of the
                  execution  hereof,  and to the rights,  if any, of any parties
                  then in possession of any part of the Premises, provided:

                  (A)      The  Mortgagee  or its  nominee  shall give notice to
                           CROET for such new sublease  within  thirty (30) days
                           after the date of such  termination  and such  notice
                           shall be  accompanied by payment to CROET of all sums
                           then due to CROET and not paid by Sublessee  pursuant
                           to this Sublease;

                  (B)      The  Mortgagee  or its nominee  shall pay to CROET at
                           the time of the  execution  and  delivery of such new
                           sublease,   any   expenses,    including   reasonable
                           attorneys'  fees,  to which  CROET  shall  have  been
                           subjected by reason of such default;

                  (C)      The  Mortgagee  or  its  nominee  shall  perform  and
                           observe all covenants herein contained on Sublessee's
                           part to be  performed  and shall  further  remedy any
                           other  conditions  which  Sublessee  pursuant  to the
                           terminated  Sublease was  obligated to perform  under
                           the terms of this  Sublease;  and upon  execution and
                           delivery of such new sublease,  any  subleases  which
                           may have theretofore been assigned and transferred by
                           Sublessee to CROET,  as security under this Sublease,
                           shall  thereupon  be  deemed  to be held by  CROET as
                           security   for   the   performance   of  all  of  the
                           obligations of Sublessee pursuant to the new lease;

                  (D)      Such new sublease  shall be expressly made subject to
                           the  rights,  if any,  of  Sublessee  pursuant to the
                           terminated sublease;

                  (E)      The Sublessee  under such new sublease shall have the
                           same  right,   title  and  interest  in  and  to  the
                           buildings  and   improvements   on  the  Premises  as
                           Sublessee had under the terminated sublease;
         (iv)     The  Mortgagee  shall  be  given  notice  of any  judicial  or
                  administrative  proceedings by the parties hereto  regarding a
                  default  of  this  Sublease,  and  shall  have  the  right  to
                  intervene therein and be made party to such  proceedings,  and
                  the parties hereto do hereby consent to such intervention.  In
                  the event that the  Mortgagee  shall not elect to intervene or
                  become  a  party  to such  proceedings,  the  Mortgagee  shall
                  receive notice of, and a copy of any award or decision made in
                  said proceedings; and


         (v)      CROET shall, upon request, execute, acknowledge and deliver to
                  each  Mortgagee,  an  agreement  prepared at the sole cost and
                  expense of Sublessee,  in form reasonably satisfactory to such
                  Mortgagee, between CROET, Sublessee and Mortgagee, agreeing to
                  all of the  provisions of this section.  The term  "Mortgage,"
                  whenever  used  herein,   shall  include   whatever   security
                  instruments  are used in the locale of the Premises,  such as,
                  without  limitation,   deeds  of  trust,  security  deeds  and
                  conditional deeds, as well as financing  statements,  security
                  agreements and other  documentation  required  pursuant to the
                  Uniform  Commercial Code. The term "Mortgagee"  shall mean the
                  holder or beneficiary of any Mortgage.  The provisions of this
                  section shall survive any termination of this Sublease.

16.      TERMINATION RIGHTS OF SUBLESSEE.  The Sublessee shall have the right to
         terminate  this Sublease in the event any of the  following  conditions
         occurs, in Sublessee's sole discretion:

         (i)      The physical  condition of Property not satisfactory to 
                  Sublessee,  or the lenders which Sublessee selects to extend 
                  financing of the  Facility or  equipment  to be used on the 
                  Premises  ("Sublessee's  Lender").  The  physical  condition 
                  of the Premises shall include, without limitation, the status 
                  of title and any industrial park  covenants,  restrictions,
                  conditions and easements to be hereafter placed upon Parcel 
                  ED-1, geological,  archeological,  environmental,  survey
                  and other developmental  matters,  federally-designated  
                  wetlands areas,  federally-designated  flood plain areas. In
                  the event  Sublessee  does not notify CROET of its intention 
                  to terminate this Sublease for failure of this condition
                  to be  satisfied  on or before  one (1) year from the date of 
                  this  Sublease,  this  condition  shall be deemed to be
                  waived or satisfied by Sublessee.

        (ii)      The Lease and the  Sublease  are not  approved by  Sublessee's
                  Lender.  In the event  Sublessee  does not notify CROET of its
                  intention  to  terminate  this  Sublease  for  failure of this
                  condition  to be  satisfied on or before one (1) year from the
                  date of this Sublease,  this  condition  shall be deemed to be
                  waived or satisfied by Sublessee.

       (iii)      Sublessee  fails to obtain all the required  governmental  and
                  regulatory authority, licenses, permits, approval and consents
                  for the  development,  use and operation of the Facility,  the
                  PSP and any other  equipment  required  for use in  connection
                  with Sublessee's business operations on the Premises.

        (iv)      Sublessee  fails  to  receive  state  and  local  governmental
                  incentives  and  inducements   satisfactory  to  Sublessee  in
                  connection  with the  development,  use and  operation  of the
                  Facility, including the PSP and any other equipment to be used
                  on the Premises (including, without limitation, ad valorem tax
                  relief/abatement    from   county   and   city    governmental
                  authorities).  Sublessee agrees to use reasonable diligence in
                  the filing  and  pursuit of all  governmental  incentives  and
                  inducements  required  or desired by  Sublessee.  In the event
                  that  Sublessee  does not  notify  CROET of its  intention  to
                  terminate  this  Sublease for failure of this  condition to be
                  satisfied on or before January 1, 2000,  this condition  shall
                  be deemed to be waived or satisfied by Sublessee.

         (v)       DOE or CROET  fails to grant  any  consents  or  approval  to
                   Sublease to Sublessee, required to be obtained by Sublessee
                  pursuant  to  the  Land  Lease  or  this  Sublease,  which  is
                  reasonably  necessary  for  Sublessee's  enjoyment,   use  and
                  operation of the Facility, the PSP, and any other equipment to
                  be utilized by Sublessee on the Premises.

         (vi)     DOE fails to enter into a written  agreement  satisfactory  to
                  Sublessee and Sublessee's  Lender on or before April 30, 1999,
                  which  provide that in the event there is a default  under the
                  Land Lease not resulting from  Sublessee's  default under this
                  Sublease,  in the  event  the Land  Lease is  terminated,  the
                  Sublease shall become a direct lease between DOE and Sublessee
                  subject to all terms of this  Sublease and the  provisions  of
                  the Land Lease  applicable  to the  Premises and DOE shall not
                  disturb any rights, interests or privileges of Sublessee under
                  the  Sublease  provided  Sublessee is in  compliance  with the
                  terms thereof.

         (vii)    DOE  terminates  the  Equipment  Lease  pursuant  to Section 3
                  thereof  in  the  event  of a  national  emergency  or in  the
                  interest of national defense,  or if the PSP is taken by power
                  of eminent domain.

        (viii)    Sublessee  determines,  as a result of a detailed inventory of
                  the PSP  components  after  the  date  hereof,  that  critical
                  components of the PSP are missing, damaged or inoperable to an
                  extent that, in  Sublessee's  business  judgment,  it would be
                  impractical to repair or replace them.

          (ix)    The DOE does not release all  existing  components  of the PSP
                  for  delivery to Sublessee  within  thirty (30) days after the
                  Facility is ready to receive the same, provided that Sublessee
                  shall have used  reasonable  efforts to agree with DOE on, and
                  to  implement,  an  appropriate  security plan so that DOE can
                  release the PSP for delivery.

           (x)    DOE's M&O contractor  fails to deliver the same to Sublessee's
                  facility  within  thirty (30) days after the Facility is ready
                  to receive the same; provided,  that Sublessee shall not be in
                  breach of the Work for Others Agreement  between Sublessee and
                  the  M&O  contractor  ("the  WFO  Agreement"),   and  provided
                  Sublessee shall have given the M&O contractor adequate advance
                  notice (at least  thirty [30] days) of the  proposed  delivery
                  date.

          (xi)    The  PSP  or  critical  components  thereof  fail  operational
                  testing and, in  Sublessee's  business  judgment,  it would be
                  impractical to repair or replace them.

         (xii)    Sublessee  determines  that  production of enriched  palladium
                  isotopes  using the PSP is not, or is no longer,  economically
                  feasible in light of then-current market conditions.

        (xiii)    The DOE's High Flux Isotope  Reactor is shut down  permanently
                  or indefinitely,  or Sublessee is not permitted  [Confidential
                  Treatment  Requested]  as  presently  contemplated  by the WFO
                  Agreement,  or if  Sublessee  is no longer given access to the
                  HFIR for isotope irradiation as presently  contemplated by the
                  WFO Agreement.

         In the event Sublessee elects to terminate this Sublease for failure of
         any of the foregoing conditions to be satisfied, Sublessee shall notify
         CROET in writing of such  election,  in which event this Sublease shall
         terminate on the date  designated  by  Sublessee,  but in no event more
         than thirty (30) days from the date of such notice.

         Furthermore,  Sublessee  shall  have the right to  terminate  by giving
         ninety  (90)  days'  notice  to CROET if CROET  fails to  substantially
         perform  or  comply  with any of its  obligations  under  the terms and
         conditions of this Sublease and continues and persists  therein for ten
         (10) days after  notice  thereof in  writing  by  Sublessee;  provided,
         however,  if such default is not reasonably capable of cure within such
         ten (10) day period,  Sublessee shall not be entitled to terminate this
         Sublease  if  CROET  promptly  undertakes  to  cure  such  default  and
         diligently pursues such cure.

         In addition,  Sublessee shall have the right to terminate this Sublease
         only as it relates to the PSP and the Equipment Lease,  with or without
         cause, on ninety (90) days' prior written notice to CROET.

         In the event of the termination of this Sublease (or the portion hereof
         relating  to the PSP) as  aforesaid,  this  Sublease  (or such  portion
         relating to the PSP) shall be of no further  force and effect,  and the
         parties  hereto shall have no further  rights,  obligations  and duties
         hereunder except that nothing  provided herein shall relieve  Sublessee
         of  the  restoration  obligations  set  forth  paragraph  3(d)  of  the
         Sublease.

17.      SUBLESSEE'S ENTRY ON PREMISES.  From and after the date of Sublease and
         ------------------------------
         prior to the  commencement of the term of this Sublease as set forth in
         Paragraph 2(a), CROET grants to Sublessee and its authorized agents and
         representatives,  the right to enter onto the  Premises  to conduct any
         surveys,  tests, analyses,  investigations,  inspections and studies as
         Sublessee may elect to determine  the  feasibility  of the  development
         contemplated by Sublessee upon the Premises. Sublessee shall indemnify,
         and hold CROET harmless from any losses, costs,  damages,  expenses and
         actions arising out of said activities of Sublessee.

18.      CROET'S OBLIGATIONS FOR COMMON AREA FACILITIES;  EASEMENTS.  CROET 
         ----------------------------------------------------------
         intends to develop the approximately  957.16 acres which it leases from
         DOE  pursuant  to Land Lease (the  "Industrial  Park  Property")  as an
         integrated  industrial  park.  In  connection  therewith,  CROET hereby
         covenants  and  agrees  to  construct  and  maintain,  or  cause  to be
         constructed  and  maintained,   all  facilities  commonly-used  by  the
         occupants of the Industrial  Park Property  (collectively,  the "Common
         Area Facilities"), including, without limitation, all roads and streets
         (which are not publicly  dedicated),  all commonly  used utility  lines
         (which are not public lines or lines of other  privately-owned  utility
         companies)  and  detention/retention  areas.  CROET  agrees to complete
         construction  of all Common Area  Facilities  necessary for Sublessee's
         use of the  Facility  on or  before  one (1) year from the date of this
         Sublease.  In the event CROET fails to construct or maintain the Common
         Area  Facilities  as  aforesaid,  thirty  (30) days after  notice  from
         Sublessee (except for emergency repairs),  Sublessee may (but shall not
         be obligated to) undertake such construction  and/or  maintenance.  Any
         amounts  expended by Sublessee  shall be immediately due and payable to
         Sublessee  and shall bear interest from the date advanced at the lesser
         of twelve  percent (12%) per annum or the maximum  amount  permitted by
         law. Sublessee shall also have the right to offset rents due under this
         Sublease for any such amounts owed Sublessee

         CROET hereby grants unto  Sublessee,  during the term of this Sublease,
         the following non-exclusive easements:

         (i)      an  ingress-egress  easement  60-feet in width for purposes of
                  ingress and egress from State Route 95 (bordering  the eastern
                  side of the  Industrial  Park Property) over such private road
                  as shall border the northern boundary of the Premises;

         (ii)     an easement for utilities (including, without limitation, gas,
                  water, electricity,  sanitary, sewer and telephone) across the
                  Industrial  Park  Property to the  boundary of the Premises at
                  such  locations  as may be  mutually  approved  by  CROET  and
                  Sublessee, such approval not to be unreasonably withheld; and

         (iii)    an easement  for  drainage of surface  storm water  across the
                  Industrial  Park Property from the Premises at such  locations
                  as may be  mutually  approved  by CROET  and  Sublessee,  such
                  approval not to be unreasonably withheld.

19.      PARAMETERS  OF LAND USE.  In  accordance  with  Condition  No. 7 of the
         ------------------------
         Land Lease, the Sublessee shall be subject to the following  parameters
         addressed within the approved environmental documentation or subsequent
         documentation which expands those parameters:

         The Environmental  Assessment  (DOE/EA-113) ("EA") issued in April 1996
         by the U.S.  Department of Energy's Oak Ridge Operations Office for the
         lease of parcel ED-1 of the Oak Ridge Reservation by the East Tennessee
         Economic Council, now CROET,  provides in subsection 2.1.3,  Industrial
         Development, that industrial use of the parcel will conform to the City
         of Oak Ridge Zoning Ordinance (Chapter 7, Sect. 6-713 IND-2, Industrial
         District),  except for certain uses not relevant to this Sublease.  The
         ordinance  referenced  is  included  as  Appendix  C to the EA,  and it
         provides in subsection  6-713(a)(l)  that  permitted  principal uses of
         industrial  districts  include,  among other  things,  "light and heavy
         manufacturing   and  processing   plants,   research  and   development
         facilities, and facilities such as processing of radioisotopes."

20.      PSP USAGE FOR NON-MEDICAL ISOTOPES. If the Sublessee desires to use the
         ----------------------------------
         PSP to produce  isotopes which are not either  [Confidential  Treatment
         Requested]  notify  DOE in writing  so that DOE can  determine  whether
         those  isotopes are  recognized by the EA covering the Premises and, if
         not so recognized,  so that DOE can process an appropriate  addendum to
         the EA, the cost of such addendum to the EA being borne by Sublessee.

21.      AMENDMENTS  TO LEASES.  CROET  covenants  and agrees  that it shall not
         ----------------------
         consent not to be  unreasonably  withheld (i) the Equipment  Lease,  or
         (ii) the Land Lease as it affects the  Premises  or the use,  enjoyment
         and operation thereof.

22.      MISCELLANEOUS.
         -------------

        (a)       CROET and  Sublessee  each warrant and  represent to the other
                  that such party has not  engaged  services  of any real estate
                  broker,  agent or finder  which  would  entitle  any person or
                  entity  to any  fee,  commission,  or  other  compensation  in
                  connection  with this  Sublease.  CROET and  Sublessee  hereby
                  agree  to  indemnify  and  hold the  other  harmless  from and
                  against  any and  all  claims,  fees,  commissions,  or  other
                  compensation  of any real  estate  broker,  agent,  or  finder
                  claiming  services to have been  rendered  for or on behalf of
                  such party in connection with the execution of this Sublease.

         (b)      At any time and from time to time upon the  request  of either
                  of the  parties  hereto or any  mortgage  lender of Sublessee,
                  CROET and Sublessee,  as the case may be, shall deliver to the
                  party  requesting  the same a certificate  stating (i)
                  whether or not this  Sublease is in full force and effect,  
                  (ii)  whether or not any rights to renew the term of this
                  Sublease have been exercised and the date on which this 
                  Sublease will  terminate,  (iii) whether or not this Sublease
                  has been modified or amended in any way and attach any copy of
                  such  modification  or amendment,  (iv) whether or not
                  there are any existing  defaults  under this Sublease to the 
                  knowledge of the party  executing the  certificate,  and
                  specifying the nature of such defaults, if any, (v) the status
                  of rent payments,  and (vi) any of the facts regarding
                  the Sublease which any mortgage lender of Sublessee may 
                  reasonably request.

(c)               This   Sublease   shall  be  governed  by,  and  construed  in
                  accordance  with,  the laws of the State of Tennessee,  except
                  that if  interpretation  or  application  of provisions of the
                  Leases  are  involved,  the  provisions  of the  Leases  shall
                  control.

(d)               This  Sublease  shall be binding  upon and shall  inure to the
                  benefit of CROET and Sublessee and their respective successors
                  and assigns.

23.      ENTIRE LEASE. This Sublease contains the entire  understanding of CROET
         and the  Sublessee  with respect to its subject  matter.  This Sublease
         reflects all agreements and  commitments  made prior to the date hereof
         with respect to this Sublease by CROET and the Sublessee.  There are no
         other oral or written understandings, terms, or conditions, and neither
         CROET nor the Lessee has relied upon any  representation  or statement,
         express or implied, which is not contained in this Sublease.

         IN WITNESS  WHEREOF,  the  parties  have  caused  this  Sublease  to be
executed on their behalf by their duly authorized representatives as of the date
first written above.

                                     CROET:
                                     COMMUNITY REUSE ORGANIZATION
                                     OF EAST TENNESSEE


                                      BY:/s/ Lawrence T. Young                 
                                         -----------------------------
                                         Print Name: Lawrence T. Young          
                                         -----------------------------
                                         Title: President and CEO              
                                         -----------------------------


                    [SIGNATURES CONTINUED ON FOLLOWING PAGE]


<PAGE>



                    [SIGNATURES CONTINUED FROM PREVIOUS PAGE]


                                             SUBLESSEE:

                                             THERAGENICS CORPORATION
ATTEST:

/s/ Jaquelyn L. Burtle                  BY:   /s/ Bruce W. Smith              
------------------------------               --------------------------
Print Name:Jacquelyn L. Burtle          Print Name: Bruce W.  Smith            
Title: Corporate Librarian              Title: Executive V. P. and CFO       





<PAGE>


                                   APPENDIX A

                   DRAWING OF PREMISES AND ADJOINING PROPERTY
                   ------------------------------------------