A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

P

package:
The packaging with its radioactive contents as presented for transport.  The types of packages covered by these Regulations, which are subject to the activity limits and material restrictions of Section IV and meet the corresponding requirements, are:

  • Excepted package;
  • Industrial package Type 1 (Type IP-1);
  • Industrial package Type 2 (Type IP-2);
  • Industrial package Type 3 (Type IP-3);
  • Type A package;
  • Type B(U) package;
  • Type B(M) package;
  • Type C package.

Packages containing fissile material or uranium hexafluoride are subject to additional requirements. [41]<
The detailed specifications and requirements for these package types are specified in the Transport Regulations, and are too complex to attempt to summarize here.  In very general terms, the stringency of the requirements for the packages (and hence the amount of radioactive material that can be carried in them) increases from (a) to (h).

package, waste:
The product of conditioning that includes the waste form and any container(s) and internal barriers (e.g. absorbing materials and liner), as prepared in accordance with requirements for handling, transport, storage and/or disposal.

packaging:
1.   The assembly of components necessary to enclose the radioactive contents completely.  It may, in particular, consist of one or more receptacles, absorbent materials, spacing structures, radiation shielding and service equipment for filling, emptying, venting and pressure relief; devices for cooling, absorbing mechanical shocks, handling and tie-down, thermal insulation; and service devices integral to the package.  The packaging may be a box, drum, or similar receptacle, or may also be a freight container, tank, or intermediate bulk container. [41]
2.   See waste management, radioactive (1).

performance assessment:
See assessment (1).

periodic safety review:
A systematic reassessment of the safety of an operational facility or activity carried out at regular intervals to deal with the cumulative effects of ageing, modifications, operating experience and technical developments, and aimed at ensuring a high level of safety throughout the operating lifetime of the facility or activity.

personal dose equivalent:
See dose equivalent quantities.

physical protection:
See protection (3).

plant equipment:

! This use of the term protection refers to protection of the plant (see protection (2)).

plant states:

operational states

accident conditions

beyond design basis

accidents

anticipated

design

normal

operational

basis

severe

operation

occurrences

a

accidents

b

accidents

accident management


a = Accident conditions which are not explicitly considered design basis accidents but are encompassed by them.
b = Beyond design basis accidents without significant core degradation.

This figure differs from that in the 1988 versions of the NUSS Codes, as follows:

    • accident conditions are now taken to include all non-operational states, rather than just design basis accidents and those enveloped by them (marked a);
    • the new category, marked b, of beyond design basis accidents which are not classified as severe accidents because there is no significant core degradation; and
    • the term accident management is applied only to beyond design basis accidents, rather than all non-operational states.

poison:
A substance used to reduce reactivity in a reactor core, by virtue of its high neutron absorption cross-section.

postulated initiating event:
See initiating event.

potential exposure:
See exposure situations.

practice:
Any human activity that introduces additional sources of exposure or exposure pathways or extends exposure to additional people or modifies the network of exposure pathways from existing sources, so as to increase the exposure or the likelihood of exposure of people or the number of people exposed. [40]

! Radioactive waste is generated as a result of practices that involve some beneficial effect, such as the generation of electricity by nuclear means or the diagnostic application of radioisotopes.  The management of these wastes is therefore only one part of the overall practice.

Contrasting term: intervention.  See also facilities and activities.
Terms such as ‘authorized practice’, ‘controlled practice’ and ‘regulated practice’ are used to distinguish those practices that are subject to regulatory control from other activities which meet the definition of practice but do not need or are not amenable to control.

preventive maintenance:
See maintenance.

preventive measures:
See nuclear damage.

probabilistic analysis:
Often taken to be synonymous with stochastic analysis.  Strictly, however, stochastic conveys directly the idea of randomness (or at least apparent randomness), whereas probabilistic is directly related to probabilities, and hence only indirectly concerned with randomness.  Therefore, a natural event or process might more correctly be described as stochastic (as, for example, in stochastic effect), whereas probabilistic would be more appropriate for describing a mathematical analysis of stochastic events or processes and their consequences (such an analysis would, strictly, only be stochastic if the analytical method itself included an element of randomness, e.g. Monte Carlo analysis).

probabilistic safety assessment (PSA):
A comprehensive, structured approach to identifying failure scenarios, constituting a conceptual and mathematical tool for deriving numerical estimates of risk.
Three levels of PSA are generally recognized.  Level 1 comprises the assessment of plant failures leading to the determination of core damage frequency.  Level 2 includes the assessment of containment response leading, together with Level 1 results, to the determination of containment release frequencies.  Level 3 includes the assessment of off-site consequences leading, together with the results of Level 2 analysis, to estimates of public risks. (See, for example, Ref. [58].)

  • living PSA: A PSA which is updated as necessary to reflect the current design and operational features, and is documented in such a way that each aspect of the PSA model can be directly related to existing plant information, plant documentation or the analysts’ assumptions in the absence of such information.

protection:
1.   (against radiation):

2.   (of a nuclear reactor) See protection system.
3.   (of nuclear material):

protection and safety:
The protection of people against exposure to ionizing radiation or radioactive materials and the safety of radiation sources, including the means for achieving this, and the means for preventing accidents and for mitigating the consequences of accidents should they occur. [40]
Safety is primarily concerned with maintaining control over sources, whereas (radiation) protection is primarily concerned with controlling exposure to radiation and its effects.  Clearly the two are closely connected: radiation protection is very much simpler if the source in question is under control, so safety necessarily contributes towards protection.  Sources come in many different types, and hence safety may be termed nuclear safety, radiation safety, radioactive waste safety or transport safety, but protection (in this sense) is primarily concerned with protecting humans against exposure, whatever the source, and so is always radiation protection.

protection system:
See plant equipment.

protective action:
1.   An intervention intended to avoid or reduce doses to members of the public in chronic exposure or emergency exposure situations.
See also remedial action.
This is related to radiation protection (see definition (1) of protection, and protection and safety).

2.   A protection system action calling for the operation of a particular safety actuation device.
This is related to definition (2) of protection.