Inmates who abuse prescription drugs and consume psychoactive substances continue to be "worrying," according to a report.
The report of the Independent Monitoring Board (IMB) to HMP Lowdham Grange states that compulsory monthly drug tests on inmates find traces of drugs in up to 20% of the results.
Some inmates also took "serious disciplinary action" to seek "refuge" from drug debt.
According to the report, a new scan device had "interrupted" the drug supply.
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The IMF said that psychoactive substances such as Spice posed a threat to the prisoners' health and a challenge to their staff if the order was maintained in Category B prison.
"Violent behavior can pose a threat to other prisoners and personnel, while the psychosis caused by others can cause long-term harm to mental health," the report says, covering the years February 2018 to January 2019.
After a Rapiscan machine was first used to scan emails sent to prisoners in April 2018, more than 100 finds were made each month. According to the report, there are now 50 to 60 finds.
The IMF also witnessed a series of unrest in Nottinghamshire Prison last year, including three outbreaks of violence in less than two weeks this past summer.
It was said that in an incident prisoners had taken control of a wing, "as two inexperienced officers on duty withdrew in the face of threatening behavior." The locally called members, however, had observed "reasonable behavior of all employees without undue reluctance" ".
The violent outbursts "have been unusual at Lowdham Grange in recent years," the report added, adding, "The management was impressed with the professional approach to managing each incident."
Mark Hanson, Serco's prison warden at Lowdham Grange, said: "We are pleased that the report recognizes that prisoners are treated fairly and humanely and benefit from good facilities.
"We also identify the areas of development and address them."
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