EXHIBIT 10.12



                                 UNSECURED NOTE

Date:             April 1, 2002

MAKER:            International Isotopes Inc., a Texas corporation

MAKER'S Mailing Address:

                  4137 Commerce Circle
                  Idaho Falls, Idaho 83401

PAYEE:            William Nicholson

PAYEE'S Mailing Address and Place for Payment:

                  121 Post Oak Lane, Suite 2105
                  Houston, TX 77024

Principal Amount:    Nine Hundred Nine Thousand Seven Hundred Thirty Seven and
                     00/100 Dollars ($909,737)

Annual Interest Rate on Unpaid Principal from Date:         Seven percent (7%)

Annual Interest Rate on Matured, Unpaid Amounts:            Ten percent  (10%)

Terms of Payment (principal and interest):

         Annual Payments:  On April 1 of each year during the term of this Note,
                           MAKER shall  make a payment of interest and principal
                           in accordance with the following terms:

         Interest:         All interest accrued for the prior year is to be paid
                           to the extent Net Profits  from the prior fiscal year
                           of MAKER are  available.  For  purposes of this Note,
                           "Net Profits" shall mean revenues less expenses,  but
                           excluding  any  taxes to be paid and prior to (i) the
                           payment   of  any  bonus   compensation   to  MAKER'S
                           management  or  employees  or (ii) the payment of any
                           dividends   or   other   distributions   to   MAKER'S
                           shareholders.  If Net Profits  from the prior  fiscal
                           year  are not  adequate  to make an  annual  interest
                           payment  when due,  then MAKER  shall be  required to
                           make  quarterly  payments (on each July 1, October 1,
                           and  January  1) of Net  Profits  until all  interest
                           payments  that were due on the previous  April 1 have
                           been paid in full,  at which time  interest  payments
                           shall  revert  back to annual  payments on April 1 of
                           each year.



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          Principal:       An annual principal payment equal to:

                           30% x (Net Profit for the prior  fiscal year less any
                           interest paid pursuant to the previous paragraph)

          Date of First Annual Payment:     April 1, 2003

          Maturity Date:    April 1, 2012

         MAKER promises to pay PAYEE  installments of principal and interest due
and  payable  in  annual  installments  on the  dates  and as  described  above,
continuing regularly until the Maturity Date, when the entire balance, principal
and accrued interest, shall be due and payable; interest being calculated on the
unpaid principal to the date of each installment paid.

         The MAKER of the Note reserves the right to prepay,  prior to maturity,
all or any part of the  principal  of the Note  without  penalty,  and  interest
immediately shall cease on any amount so prepaid.

SECURITY FOR PAYMENT: This Note is unsecured.  Without the prior written consent
of MAKER,  which consent  shall not  unreasonably  be withheld,  PAYEE shall not
pledge any assets as security for repayment of any  obligation,  except to Texas
State Bank or any other financial  institution that becomes MAKER'S primary bank
lender.

         MAKER  promises  to pay to the order of PAYEE at the place for  payment
and according to the terms of payment the principal  amount plus interest at the
rates  stated  above.  All unpaid  amounts  shall be due by the final  scheduled
payment date.

         On default in the  payment  of this Note or in the  performance  of any
obligation  hereunder,  the unpaid principal balance and earned interest on this
Note shall  become  immediately  due at the  election  of PAYEE.  MAKER and each
surety, endorser, and guarantor waive all demands for payment, presentations for
payment, notices of intention to accelerate maturity, notices of acceleration of
maturity, protests, and notices of protest.

         If this Note is given to an attorney for collection or enforcement,  or
if suit is brought for  collection  or  enforcement,  or if it is  collected  or
enforced through probate,  bankruptcy, or other judicial proceeding,  then MAKER
shall pay PAYEE all costs of collection and  enforcement,  including  reasonable
attorney's  fees and court costs,  in addition to other amounts due.  Reasonable
attorney's  fees shall be 5% of all  amounts  due  unless  either  party  pleads
otherwise.



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         Interest  on the debt  evidenced  by this  Note  shall not  exceed  the
maximum  amount of  nonusurious  interest  that may be  contracted  for,  taken,
reserved, charged, or received under law; any interest in excess of that maximum
amount shall be credited on the principal of the debt or, if that has been paid,
refunded.  On any  acceleration  or required or  permitted  repayment,  any such
excess hall be canceled  automatically  as of the acceleration or prepayment or,
if already paid,  credited on the principal of the debt, or, if the principal of
the debt has been paid, refunded.  The provision  overrides other  provisions in
this and all other instruments concerning the debt.

         This Note shall be construed in  accordance  with the laws of the State
of Texas.

         When the context  requires,  singular  nouns and  pronouns  include the
plural.

         This  Note  supercodes  and is in lieu  of all  agreements  and  notes,
whether  written or oral,  between MAKER and PAYEE  preceeding  the date of this
Note, and all such prior notes and/or  agreements  are hereby  declared null and
void.

                                         INTERNATIONAL ISOTOPES INC.


                                         By:     /S/ Steve Laflin  3-29-02
                                                 -------------------------
                                         Name:   Steve Laflin
                                         Title:  President & CEO



 Acknowledged by PAYEE;

 /S/ William Nicholson
 ---------------------
 William Nicholson





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