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Re­ac­tor an­a­lyst Lin­ina Bed­hesi is proof that de­ter­mi­na­tion and hard work does pay off

The South African Nu­clear En­ergy Cor­po­ra­tion SOC Ltd (Necsa) houses the coun­try's only nu­clear re­search re­ac­tor which is by far Africa's largest pro­ducer of a range of med­i­cal iso­topes that are used for di­ag­nos­tic pur­poses and the ther­a­peu­tic treat­ment of can­cer.

Be­fore the nu­clear re­search re­ac­tor starts its 30-day cy­cle, Lin­ina Bed­hesi is en­trusted with the job of per­form­ing cal­cu­la­tions to en­sure that the sys­tem op­er­ates safely.

The 27-year-old is a re­ac­tor an­a­lyst at Necsa and her job en­tails us­ing cal­cu­la­tion codes to carry out safety anal­y­sis for the re­ac­tor's core.

She per­forms heat and spent fuel cal­cu­la­tions for the South African Fun­da­men­tal Atomic Re­search In­stal­la­tion 1 (SA­FARI-1).

SA­FARI-1 is a 20 megawatt tank-in­pool type ma­te­rial test­ing nu­clear re­search re­ac­tor. It is owned and op­er­ated by Necsa and lo­cated at Pelind­aba, 30 kilo­me­tres west of Pre­to­ria.

Ben­e­fits of med­i­cal iso­topes

Mil­lions of peo­ple have ben­e­fited from the med­i­cal iso­topes orig­i­nat­ing from SA­FARI-1. Pa­tients in South Africa and in­ter­na­tion­ally are treated with typ­i­cal ra­dioiso­topes.

For the iso­topes to be pro­duced and for SA­FARI-1 to keep run­ning, Bed­hesi per­forms core-fol­low cal­cu­la­tions to es­tab­lish the amount of fuel burnt dur­ing the re­ac­tor's cy­cle. With­out th­ese cal­cu­la­tions, the re­ac­tor can­not start.

“Heat­ing cal­cu­la­tions are im­por­tant for the safety of the re­ac­tor. We need to know the amount of heat re­leased per fis­sion re­ac­tion and the spa­tial dis­tri­bu­tion of heat so that we can im­ple­ment cool­ing in high tem­per­a­ture re­gions,” she ex­plained.

“If we know that, we can im­ple­ment cool­ing in the re­ac­tor. And this is one of the big­gest safety cal­cu­la­tions that is needed,” she added.

For spent fuel cal­cu­la­tions, Bed­hesi uses a cal­cu­la­tional computer code to cal­cu­late what amount of ura­nium and plu­to­nium is present in a spent fuel assem­bly for stor­age pur­poses.

Other sci­en­tists or tech­ni­cians who do op­er­a­tional work at SA­FARI-1 send Bed­hesi data about the cy­cle un­der op­er­a­tion.

If any safety pa­ram­e­ter is not met, it will com­pro­mise the safety of the re­ac­tor and the process can­not be ini­tialised if Bed­hesi tells the sci­en­tists at SA­FARI-1 that it is not safe.

She works with three col­leagues who per­form the same cal­cu­la­tions to en­sure that no mistakes are made and that there is con­sis­tency.

The nu­clear re­ac­tor has a builtin fea­ture called a scram, which au­to­mat­i­cally shuts down when some­thing ir­reg­u­lar hap­pens dur­ing the process.

When­ever that hap­pens, the sci­en­tists ask Bed­hesi and her team if they should al­low the re­ac­tor to reach the pa­ram­e­ters deemed safe.

“We will then do the cal­cu­la­tions and gen­er­ate a re­port. Some­times we will in­clude a sec­tion of ob­ser­va­tions in the re­port to tell them that it is not con­sis­tent with what we are used to see­ing, and they should de­cide whether to start up or not,” she said.

Living her dream

Bed­hesi was ap­pointed as a re­ac­tor an­a­lyst at Necsa in Au­gust 2017 and it is al­ready a job that is close to her heart.

She does not mind driv­ing for about 45 min­utes ev­ery morn­ing to work and she cer­tainly does not mind the wildlife she gets to see reg­u­larly.

“There are ze­bras and mon­keys here at Necsa. It is a very re­fresh­ing sight,” she said.

She holds an un­der­grad­u­ate de­gree in Nu­clear Sci­ence and Engi­neer­ing from the Univer­sity of Wit­wa­ter­srand (Wits). Bed­hesi also has an Hon­ours De­gree in Physics from Wits and is in the process of ob­tain­ing an MSc (Physics). Prior to en­rolling at Wits, she had a schol­ar­ship to study bi­ol­ogy in In­dia.

A cou­ple of years ago, she found her­self read­ing a brochure on BSc Nu­clear Sci­ence and Engi­neer­ing.

“While read­ing the brochure, I found my­self more in­ter­ested in the nu­clear sciences. I think it is be­cause my par­ents had a his­tory of can­cer. It was just an emo­tional jour­ney for me,” she said.

Can­cer pa­tients un­dergo dif­fer­ent types of ther­apy in hos­pi­tals and of­ten med­i­cal pro­fes­sion­als use iso­topes, which are pro­duced by SA­FARI-1.

De­ter­mined to suc­ceed

“I reg­is­tered for this course. I saw a pic­ture of SA­FARI-1 in the brochure and told my­self that one day I will work at Necsa. At the end of my sec­ond year of study, I con­tacted Necsa's hu­man re­source sec­tion and asked if I could do va­ca­tion work and I was granted the op­por­tu­nity. That is how my jour­ney be­gan, in De­cem­ber 2013,” she said.

When her peers went home for school hol­i­days, Bed­hesi made her way to Necsa to gain work ex­pe­ri­ence.

“I also did my Hon­ours project at Necsa, and am con­tin­u­ing with my Masters work here as well,” she said.

She said there is a huge gap of knowl­edge be­tween her se­niors and the ju­niors in the field, which needs to be filled.

“There are many peo­ple in the late years of their ca­reers and there are very young peo­ple.There is also a lack of skills,” she said.

How­ever, Bed­hesi said the nu­clear sci­ence field is very re­ward­ing and her hard work pays off.

She gets to at­tend in­ter­na­tional con­fer­ences and to present her work to peo­ple from across the globe.

“Dur­ing my time at Necsa, I have ob­tained two awards at the South African In­sti­tute of Physics Con­fer­ence for my MSc work. I also re­ceived two post­grad­u­ate merit awards from Wits Univer­sity. My work is ex­tremely ex­cit­ing, and I en­joy the chal­lenges that come with it,” she said.

What is most ex­cit­ing for her is that a fe­male sci­en­tist is given the same op­por­tu­nity as males in the sci­ence field, although she feels that sci­ence is still very much male­dom­i­nated glob­ally.

“I was the only fe­male that grad­u­ated in physics in my class in 2015 at un­der­grad­u­ate level,” she said.

Healing the world through nu­clear

The pro­duc­tion of med­i­cal iso­topes is one of the most im­por­tant func­tions of the re­ac­tor. There is an iso­tope that Necsa is a key dis­trib­u­tor of, and it is called the Molyb­de­num-99 (Mo-99). It is used for di­ag­nos­tic imag­ing, can­cer re­search or gen­er­ally in nu­clear medicine.

Necsa sup­plies a third of the Mo99 de­mand glob­ally. In 2014, it was said to be the third largest pro­ducer of Mo-99 in the world.The work done at SA­FARI-1 is not only im­pact­ing on South Africa but many parts of the globe.

Mo-99 orig­i­nally had to be im­ported into South Africa weekly, but since 1993, with its unique abil­ity to man­age vir­tu­ally the en­tire nu­clear pro­duc­tion cy­cle, Necsa has be­come the sole lo­cal and an im­por­tant in­ter­na­tional sup­plier of Mo-99.

Necsa also pro­duces Io­dine-131 and Lutetium-137, among many other iso­topes, and th­ese are also used in di­ag­nos­tic imag­ing and ther­apy.

Re­ac­tor an­a­lyst Lin­ina Bed­hesi is mak­ing a name for her­self in the nu­clear in­dus­try.

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