Abstract: A device for carrying out a surveillance program to monitor the environmental effect of radiation and high-temperature oxygenated water on the shroud material in an operating reactor. The device is a holder containing shroud material specimens and encapsulated neutron flux monitors. The holder is installed on the shroud wall and left in place for a predetermined period of reactor operation time for the purpose of monitoring the neutron fluence effect on the shroud material specimens housed in the holder. The specimen holder is later removed from the reactor. The specimens are removed from the holder and examined in a laboratory to determine any changes in material properties. The specimen holder comprises a bolt-like device having a hollow head and a threaded shaft. The hollow head provides space for material specimens and neutron flux monitors. The specimen holder is attached to the shroud wall by screwing the threaded shaft into a threaded hole in shroud wall.