Hery Adrial PTRKN-BATAN Disampaikan pada Coaching Komputasi Pemodelan untuk Mendukung Analisis Sistem Keselamatan Reaktor Fisik PPIN-BATAN: 1 April – 31 Mei 2013 Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Buildup and depletion of nuclides in fuel (FEVER)

Berubahnya komposisi bahan bakar dalam teras reaktor ketika reaktor dioperasikan. Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april Terjadi : 1. konsumsi isotop fisil (bahan bakar) 2. diproduksinya hasil fisi Menurut duderstadt ; Analisa atau perhitungan yang mengkaji tentang interaksi antara distribusi core power dengan waktu atau deplesi inti didalam teras disebut sebagai Anlisa deplesi atau burnup

 1. Keselamatan reaktor :  2. Manajemen reaktor  3. Produksi Isotop. Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013

Sejak neutron dilahirkan dalam reaksi pembelahan, nwuton bergerak dengan kecepatan tinggi di dalam teras dan berinteraksi dengan berbagai material, berdifusi serta kemudian diperlambat, neutron berada dalam berbagai tingkatan energi dan bergerak kesegala arah. Proses reaksi nuklir pada teras reaktor

Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Moderator adalah bagian dari reaktor yang bersifat memperlambat laju neutron dari energi saat membelah sekitar 2 Mev ke energi termal 0,0252 ev

 Pada saat reaktor beroperasi maka pada bahan bakar akan terjadi reaksi nuklir. Sebagian bahan bakar mengalami fisi, Sebagaian lagi berubah menjadi unsur aktinida melalui tangkapan neutron (mengikuti rantai nuklida Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Terbentuknya nuklida-nuklida hasil reaksi pembelahan maupun hasil peluruhan nuklida serta anak luruhnya (daughter) sangt berpdengaruh terhadap operasi reaktor

Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013  Beberapa diantaranya mempunyai daya tangkap neutron thermal yang tinggi sehingga sering disebut racun  Contoh terbentuknya xe dan Sr dalam reaksi fisi

Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Heavy Metal Chains Arrow up :neutron capture Arrow down:(n,2n) reaction Arrow left :electron capture Arrow right:  decay or  decay for Am242 m

Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013

 1. peluruhan spontan dari inti nuklir,misalnya peluruhan radioaktif dari inti produk fisi yang pada umumnya tidak stabil. Reaksi peluruhan ini hanya tergantung pada sifat dari inti tersebut.peluruhan radioaktif  2. interaksi antara dua inti nuklir atau inti dengan partikel lain, termasuk dalam katagori ini misalnya tumbukan neutron dan neutron. Reaksi ini tidak hanya bergantung pada sifat inti yang berinteraksi, namun juga terhadap kecepatan (atau energi) dari inti dan partikel yang terlibat dalam interaksiinteraksi antara dua inti nuklir atau inti dengan partikel lain Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013

 1. Production/removal equations (Nuclide depletion equation (Bateman)) Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013

Time rate of change in concentrat ion of isotope i from fission of all fissionable nuclides from neutron transmutatio n of all isotopes including (n,gamma), (n,alpha), etc. from decay of all isotopes including beta,alpha, etc. by fissions by neutron capture (excludin g fission) by decay Removal rate per unit volume of isotope i Production rate per unit volume of isotope i

Neutron flux, n/cm 2 -s Concentration of isotope j, atoms/cm 3 Microscopic fissions cross- section of isotope j, cm 2 Fission fraction for the production of isotope i from fission of isotope j, n/cm 2 -s All fissionable nuclide Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Laju Produk Fisi (Fission production rate)

Concentration of isotope k, atoms/cm 3 Neutron flux, n/cm 2 -s Integrated over all isotopes Microscopic capture cross- section (minus fissions) of isotope k, cm 2 Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Laju Produksi Capture (Capture production rate)

Fission removal rate Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Concentration of isotope l, atoms/cm 3 Neutron flux, n/cm 2 -s Microscopic fissions cross- section of isotope j, cm 2

Decay production rate Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Concentration of isotope l, atoms/cm 3 Integrate over all isotopes Decay constant (equal to ln(2)/half-life) of isotope l, 1/s

Capture removal rate Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Neutron flux, n/cm 2 -s Concentration of isotope l, atoms/cm 3 Microscopic capture cross- section of isotope j, cm 2

Decay removal rate Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Concentration of isotope l, atoms/cm 3 Decay constant (equal to ln(2)/half-life) of isotope l, 1/s

Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013

22 2. Neutron Transport Equation (Boltzmann)

 3 Persamaan Diffusi Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 satu dimensi : FEVER

 Build up & deplesi Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013 Fever VSOP Origen dll depletor Code-code yang dipakai

 Menggunakan program FEVERFEVER  FEVER :A One-dimensional Few-group energy  GENERAL ATOMIC November 28, 1962  Bahasa: FORTRAN-II  Dasar Theori :Persamaan teori diffusion.  Metode penyelesaian : Beda Hingga  Group energi ; 4 group energi Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013

FEVER  FEVER code development effort was the need to evaluate the effects of fuel depletion and control rod withdrawal upon the power distribution of the HTGR  Flux, power, and effective m u l t i p l i c a t i o n f a c t o r s a r e computed by means of a group diffusion calculation l i m i t e d to 150 mesh points in up to 20 regions and using a maximum of 4 energy groups

FEVER  The isotopic depletion is accomplished by finite difference approximations,using region a v e r a g e fluxes and nuclide concentrations r a t h er than m e s h p o i n t values.

 NOTES ON INPUT DATA  Input data for FEVER are divided into two types:  1. The cross section and miscellaneous data library.  2. Case input. Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013

 VSOP UTILITY VSOP UTILITY Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013

SEKIAN TERIMA KASIH

2012 September 36 I-135/Xe-135 Kinetics Fissions 135 Te 135 I  - (  1/2 =18 s) 135 Xe  - (  1/2 =6.585 h) Burnout by neutron absorption  - (  1/2 =9.169 h) We will see that production of 135 Xe by beta decay of 135 I dominates over its direct production in fission.

 When nuclear fuel is “burned” in a reactor, changes occur in the fuel. These changes go under the general name of “ fuel (isotopic) depletion”.  Here we shall look at the changes which happen in the standard CANDU lattice, and at the quantitative changes in the reactivity and other nuclear properties of the lattice.  Although we are looking specifically at the standard CANDU, a similar analysis needs to be done for any reactor which needs to be studied September37

The following changes occur cumulatively in CANDU nuclear fuel with time:  The U-235 depletes (i.e., its concentration, which starts at 0.72 atom% for fresh natural uranium, decreases)  Fission products accumulate; most of these are radioactive, and many have a significant neutron-absorption cross section  Pu-239 is produced via neutron absorption in U-238 and two beta decays: 238 U + n  239 U*  239 Np +  239 Np  239 Pu +  2008 September38

 Pu-239 participates in the fission chain reaction  while it keeps being created at about the same rate from U-238, its net rate of increase slows.  Further neutron absorptions lead from Pu-239 to Pu-240 (non-fissile), then Pu-241 (fissile)  Other higher actinides are also formed (e.g., curium, americium)  The total fissile fraction in the fuel (U-235+Pu- 239+Pu-241) decreases monotonically September39

 Two new reactor-physics concepts, on which we have not really focused up to now, have to do with the evolution in time of the fuel.  These 2 concepts are those of fuel irradiation and burnup, and are very important.  These concepts are related because, in a way, they are both a measure of the “age” of the fuel in the reactor September40

Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013

 1. Control-poison concentrations for the "just c r i t i c a l "  c a s e.  2. Maximum Keef at operating t e m p e r a t u r e with all  controlpoison removed (if this option is selected).  3. Cold shutdown K eff at shutdown t e m p e r a t u r e with  xenon removed and all control poison fully i n s e r t e d  (if this option is selected).  4. Conversion ratio.  5. All nuclide c o n c e n t r a t i o n s by region.  6. Weight of heavy isotopes (total and by region).  7. Flux and power d i s t r i b u t i o n s.  8. Neutron balance ( s o u r c e, removal, leakage, and  a b s o r p t i o n r a t es p e r source neutron, and  fractional a b so r p t i o n s and productions for all  m a t e r i a l s in the p o w e r - g e n er a t i n g volume). Presentasi Coaching VSOP PPIN- Batan, Kamis 11 april 2013