Castle Hill High School: Radioactive ‘yellow cake’ discovered on Sydney campus
- Uranium powder found in school store
- The Hazmat team should remove it this week
One of Australia’s largest public schools has been partially closed after radioactive material that could cause kidney damage was found in a warehouse.
A box labeled ‘Yellowcake’, which is a concentrated powder of uranium oxide, was found on a science storage shelf at Castle Hill High School, northwest of Sydney.
The box is believed to have been in the room for decades and was only discovered after white powder, suspected to be asbestos, fell on it.
The school was at the center of an asbestos scare in 2020 with several classrooms closed for a month after the dangerous material was detected in the roof.
A box labeled “Yellowcake”, which contains concentrated uranium oxide powder, was found on a science storage shelf at Castle Hill School. Pictured: An Indian worker wearing protection handles Yellowcake

A teacher said the headmaster of Castle Hill School had confirmed that access to the science reserve was off limits. The school was at the center of an asbestos scandal in 2020

Teachers were told the science chemical warehouse was strictly off limits until further notice in an email from Castle Hill School principal Georgina Fleming (pictured)
A school teacher said news.com.au that “the incompetence is astounding”.
“Somehow it got put in a red box and left in the cellar…forever,” he said.
Teachers were told the science chemicals warehouse was strictly off limits until further notice in an email from Castle Hill School principal Georgina Fleming.
Ms Fleming said in the email that the school was “testing for asbestos and other suspected materials”.
The room remains “isolated and secure” until the material is properly tested and likely removed by a hazardous materials team this week.
Parents and guardians were also notified by email.
In the 1960s, students were given yellow cake powder to trigger radiation counters during classroom science experiments.
Yellowcake is radioactive, but not strongly. Its lifespan is extremely long, with a “half-life” of over 4 billion years, which means it emits radiation at a slow rate.
The main reason it is considered toxic is that it can cause kidney damage if inhaled.
The material is derived from the crushing and chemical processing of uranium ores.
The Ministry of Education confirmed in a statement that “potentially hazardous material” was found in a “locked science warehouse” at the school on August 30.
“The stash was not accessible to students and the material was in a sealed box and would have been used to support science experiments in the past,” the statement said.
The statement said the science block was cleared after inspection as “safe for normal use.”

The poisonous concentrated uranium powder is thought to have sat on the shelves of science reserves for 50 years. Pictured: Image of a wine cellar

Castle Hill School informed parents in an email of the yellow cake scare, but the science pad is considered safe to use as normal.
Staff and students complained for several years before 2020 that strange dust was falling from ceilings before asbestos was identified.
Vicky Brewer, then headmistress of the school, who retired in 2021, reportedly ignored the complaints.
The New South Wales Department of Education received a positive asbestos test result from the school four years earlier in 2016, but told the school the result came back negative.
Daily Mail Australia has contacted the Department for Education and Castle Hill School for comment.