Solid Radioactive Waste Strategy Report.pdf - UK EPR

EPR UK
N° NESH-G/2008/en/0123
REV. A PAGE 166 / 257
10.3.2.2 Radioactive Contamination
Radioactive contamination presents a radiological hazard to operators through inhalation,
ingestion or ingress through open wounds resulting in internal irradiation of organs. Internal
irradiation may also result from contamination of the skin with beta or gamma emitting
radioisotopes. There is also the potential for increased public dose following release to
environment. In normal operations the operator will be isolated from contamination through
primary containment systems provided by the equipment or waste packaging. Further control of
radioactive contamination is provided by the provision of appropriate local extract and ventilation
systems to ensure that where there is a likelihood of generation of free particulates these will be
entrained into the building ventilation system and captured in abatement systems, such as
HEPA filtration. The resulting air flow will then be monitored, to confirm that any residual activity
levels are within the discharge limits specified in the plant RSA authorisation prior to discharge
into the atmosphere. In addition to the capture of contamination at source, regular radiological
surveys will be carried out to monitor for the presence of any contamination.
Abnormal events such as dropped loads may result in operator injury and / or radiological
release if containment fails. Mechanical handling equipment will be designed in accordance
with relevant standards with appropriate safety systems to prevent dropped loads. The number
of waste or spent fuel package movements shall be minimised as far as practicable and where
necessary carried out at minimum lift heights. Where waste or fuel is containerised the package
itself will afford varying degrees of protection to the waste package against dropped load/impact
scenarios. Operators will be trained in the safe connection and use of lifting equipment.
Another abnormal event may be the failure of a vessel or service line containing liquid. All
equipment will be built to approved UK and international standards and commissioned (i.e.
thoroughly and methodically tested) prior to use. The waste and spent fuel management
facilities will be designed to provide containment in the event of a spill of material (such as
resulting from a pipe or tank rupture or internal flooding) by for example the use of bunds and
impermeable floors where appropriate.
Each area of the waste and spent fuel management facilities will be appropriately designated
and the contamination control measures put in place will be commensurate with that
designation. An example of such a control measure for a contamination hazard is to maintain
the area at a negative pressure to the surrounding areas. This ensures that in the unlikely event
of a release of contamination it is retained in the area of origin. There is also the provision of
continuous air monitoring which alarms on detection of mobile airborne contamination.
10.3.2.3 Criticality
Criticality can only occur if there is an accumulation of fissile material with appropriate geometry
and neutron moderation to sustain a nuclear chain reaction. Whilst accidental nuclear criticality
incidents are, by their nature rare and short lived, they do result in the generation of pulses of
high levels of gamma and neutron radiation which are harmful to unshielded personnel in the
immediate vicinity.
It is not anticipated that any of the solid operational or decommissioning wastes generated
during the reactor lifecycle will contain more than trace amounts of fissile material. All waste
streams will be monitored to ensure that they do not contain unexpected fissile material. The