Ionising Radiations Code of Practice & Guidance Contingency Arrangements

Transcription

1 Ionising Radiations Code of Practice & Guidance Contingency Arrangements Where any radiation user uses a source of ionising radiations, which may for example include working with sealed (closed) sources, unsealed (open) sources, geological specimens, or x-ray generator, they shall ensure that a suitable and sufficient prior risk assessment has been completed. The prior risk assessments will be specific to the work being undertaken and will identify any reasonably foreseeable events that could cause a radiation accident. A radiation accident is an accident or incident where immediate action would be required to prevent or reduce the radiation exposure to employees or any other persons to ionising radiation. The purpose of the contingency plan is to ensure, as far as is reasonably practicable, the restriction of exposure to ionising radiation and the health and safety of persons who may be affected by the identified radiation accident. In compilation of the contingency plan, consultation is to be undertaken with the College RPO/RPA. The Divisional / Group Heads are responsible for ensuring that suitable and sufficient risk assessments, Local Rules and contingency arrangements are in place prior to the work with ionising radiations commencing. The RPS and users will assist in the production of the risk assessments, the writing of local rules and the implementation of contingency arrangements as appropriate. Definitions Radiation User / User A Radiation User / User is a person who is registered by the College to undertake work using ionising radiations. Radiation Employer The College is classed as a radiation employer where it undertakes work or practices involving the use of ionising radiations RPA Radiation Protection Adviser RPO Radiation Protection Officer IRR99 Ionising Radiations Regulations 1999 RPS Radiation Protection Supervisor Code of Practice 1. Requirement for Contingency Arrangements The College is required (under IRR99) to have contingency arrangements 1 in place for processes where the prior risk assessment has determined that there is a reasonably foreseeable risk of a radiation accident. Such risks shall have been identified in compliance with the following section of the manual. IRPM-IRCP-002 (Work Registration & Risk Assessments) Where contingency arrangements are required, their nature and scope shall be detailed in Local Rules, which are also required in all radiation areas, as described in the following manual section. 1 The Reactor Centre at Silwood Park has contingency arrangements in compliance with Nuclear Site Licence Conditions. In general these will take precedence over this manual section. Ref No. IRPM-IRCP-010 Page 1 of 6 September 2015

2 IRPM-IRCP-006 (Completion of Local Rules) The purpose of the contingency arrangements is to restrict any radiation exposure of College employees and to others including College Security staff, emergency services and members of the public, that arises from an accident / incident. Reasonably foreseeable incident scenarios 2 might include a fire or explosion in a College Laboratory releasing radioactive materials into the environment, a dropped radioactive closed source in an instrument laboratory, a small spill of radioactive material on the open bench or an X- ray generator failing to terminate. Only by carrying out a suitable and sufficient risk assessment as part of the work registration process, will this be determined. The process of developing contingency arrangements requires thought to be given beforehand to the correct course of action to be taken in the event of an incident, the recording of those actions in a and the training of those identified to implement the plan. For most cases at Imperial College the contingency arrangements are going to be similar to those required for best laboratory practice and will naturally form part of Local Rules without significant extra resource required to develop the contingency plans. The likely elements of a contingency plan are shown in the following table. The guidance, which follows, can be used to determine the relevance of the table entries. Factor Comment / Example Person responsible for implementing the Contingency plan. Likely to be the Radiation Protection Supervisor Determining the extent of the incident Use of suitable radiation and contamination monitors / radiation user reporting a spill Use of barrier / door locks / tape to secure area, Securing the Area (immediate mitigation) thus ensuring exposure is minimised and contamination spread is avoided. Personal Protective Equipment Personal Protective Equipment which is required in addition to that which is mandatory Additional Personal Dosimetry Personal Dosimetry that is required in addition to that provided for use by radiation users Appropriate Training & Rehearsal Plan-specific training required and arrangements and frequency of plan rehearsals Radiation Protection Advice, Support and Reporting Arrangements Contact details for the Radiation Protection Adviser / Officer 2. Implementation of s Contingency arrangements for radiation accidents or incidents, including a description of the accidents or occurrences to which they relate, are to be detailed in Local Rules. Contingency plans are to be brought to the attention of any persons who may be affected by the accidents or 2 A reasonably foreseeable incident scenario is more than simply a credible situation, which might lead to a radiation accident. The degree of assessment required in developing a plan should be proportional to the radiation risk thus a large F-18 spill will require more assessment than a small H-3 spill. A spill of P-32 onto someone s hand in a radioisotope laboratory is reasonably foreseeable; whereas an aeroplane crashing into the same laboratory would not be considered so even though it is credible (radiation risks would be inconsequential should this actually occur). Ref No. IRPM-IRCP-010 Page 2 of 6 September 2015

3 occurrences to which they relate, including those persons who may be required to take action in implementing those plans. The RPS and other relevant personnel are to be provided with training and instruction appropriate to the actions that they may be required to take. The effectiveness of any contingency plan will be dependent upon the timeliness of actions taken by appropriately trained personnel. For this reason, all relevant personnel will participate in periodic planned rehearsals. Records of these rehearsals will be retained together with observations and recommendations for improvements. Guidance 1. s & Local Rules Contingency plans should be a part of Local Rules and in most cases best laboratory practice and working to the rules will suffice. Information on local rules can be found in the following manual section: IRPM-IRCP-006 (Completion of Local Rules) The RPS should make all radiation users aware of the local rules, ensuring that they are read and understood before starting work with ionising radiations. Where contingency arrangements are present the RPS should make the radiation users aware of procedures, equipment, personal protective equipment and spill kits that might be required to action the contingency plan. 2. Developing the Plans This section contains a few examples of how contingency plans might be developed for a number of possible scenarios. The examples demonstrate the process of information collection and assessment, which is used to develop the plans and local rules. This process should not be considered separate to the work registration (prior risk assessment) process adequately completed work registrations with attached protocols will more than likely be sufficient for developing the plans. 2.1 Laboratory Spill Nature of the work P-32 PAGE Work Nature of radiation hazard P-32, Beta emitter (High Energy) Physical nature of Wet Chemistry, large volumes of buffer solution A spill of stock isotope onto bench Foreseeable incidents A spill of stock isotope onto exposed skin A large spill of buffer solution onto the floor Procedure for dealing with a spill on the bench Procedure for dealing with personal contamination Procedure for dealing with a large spill of low activity radioactive liquid 3 In general the content will include all of those shown in the COP table on page 2. Ref No. IRPM-IRCP-010 Page 3 of 6 September 2015

4 Equipment 4 Spill Kit (small volume, high activity) Personal Decontamination Kit Spill kit (large volume) Contamination monitoring equipment In developing a contingency plan based on the above scenario you should consider consulting the following manual sections: IRPM-ICRP-016 (Decontamination Procedures) IRPM-ICRP-023 (Isotope Data) IRPM-ICRP-032 (Personal Protective Equipment) In developing the plan for the above scenario, it is not sufficient to simply reference the documents or copy the content into the Local Rules. For some circumstances it will be appropriate to reference the Decontamination Procedure if they wholly and entirely deal with the foreseeable scenario as assessed. Otherwise, the manual guidance should be used as the basis for developing plans that meet the specific requirements on a case-by-case basis. 2.2 Dropped Closed Source Nature of the work Nature of radiation hazard Physical nature of Densitometry work using radioactive closed sources in a rig Ba-133 high activity sealed sources, activity 2 GBq, radiation exposure to wholly exposed source at contact : 50 msv/h gamma Sources are small, need to be handled with remote tongs Source drops from rig onto floor Foreseeable incidents Source drops from rig onto floor into surface water drain Procedure for dealing with a dropped source Procedure for pre-checks prior to source removal (reference in local rules are subject to a separate operational procedure) Remote Handling Tongs Equipment 4 Drain Covers Radiation Monitor In developing a contingency plan based on the above scenario you should consider consulting the following manual sections: IRPM-ICRP-005 (Restriction of Exposure) IRPM-ICRP-023 (Isotope Data) IRPM-ICRP-032 (Personal Protective Equipment) In developing the plan for the above scenario, it is not sufficient to simply reference the documents or copy the content into the local rules. This example represents work in the College, which is more specialised and unique compared to more routine isotope work. However, the principles in developing the foreseeable scenarios and contingency plans are no different. 2.3 Release of Radioactive Gas/Vapour e.g. I-125 Inhalation Hazard 4 This list is not exhaustive and is for illustration only. Ref No. IRPM-IRCP-010 Page 4 of 6 September 2015

5 Nature of the work Nature of radiation hazard Physical nature of Foreseeable incidents Equipment 4 I-125 Iodination Work in a Controlled Area laboratory I-125 is a low energy x-ray/gamma emitter. The target organ for internal exposure is the thyroid. I-125 is fairly radiotoxic and only small amounts need to be inhaled for an appreciable dose to be delivered. I-125 in the free state (i.e. as NaI) is volatile. This increases the inhalation hazard. Bound I-125 can also present an inhalation hazard if it undergoes appreciable heating with acidification. I-125 Spill inside fume cupboard I-125 Spill outside fume cupboard Known inhalation of I-125 during experiment Procedure for dealing with I-125 spill inside fume cupboard Procedure for dealing with I-125 spill outside fume cupboard Procedure for dealing with a known or suspected intake of I- 125 I-125 Spill Kit Solution of alkaline Sodium Thiosulphate Contamination Monitor Potassium Iodide tablets In developing a contingency plan based on the above scenario you should consider consulting the following manual sections: IRPM-ICRP-005 (Restriction of Exposure) IRPM-ICRP-023 (Isotope Data) IRPM-ICRP-032 (Personal Protective Equipment) In addition, due to the severity of the hazard, you would be expected to consult with the College RPA/RPO during the work registration development phase. This is in order to develop specific contingency plans for your work, which you may have insufficient knowledge or experience to undertake on your own. For example, for a suspected I-125 intake, rapid deployment of contingency arrangements including the issue of Potassium Iodate tablets may be required which will involve the RPA and College Appointed Doctor. 2.4 Loss/Damage of HASS Nature of the work Nature of radiation hazard Physical nature of Foreseeable incidents Irradiation of biological samples. Cs-137 high activity sealed sources, activity up to 60 GBq. Radiation exposure to wholly exposed source not possible under normal conditions. Sources are built into irradiator units and are shielded so that user exposure to an unshielded source is not possible. Background gamma dose rates are up to about 5Sv hr -1 in some areas around irradiator units. Loss of theft of irradiator unit. Failure of mechanisms on irradiator unit. Failure of room security measures. Room defects. Malicious damage to room/ irradiator unit. Ref No. IRPM-IRCP-010 Page 5 of 6 September 2015

6 Fire/flood. Spillage of experimental samples. Loss or theft of the HASS source. Call the RPA/O if they are not already present. The RPA/RPO can then ensure the correct procedures are followed and the correct notifications of the necessary agencies are made and necessary written reporting carried out. Fault with locking mechanisms or keys to open rooms containing HASS sources. Immediately contact the Administrator, RPA/O if they are not already present. Flooding of the area containing the HASS source. Leave and secure the room at once. Report to the RPA/O immediately. Defects in any part of the room. Report to the RPA/O and the Administrator as soon as possible. Any signs of malicious damage to rooms and/or equipment containing HASS sources. Report to the RPA/O at once. Loss of any keys to access irradiator rooms or other HASS areas must be reported to the RPA/O and the Administrator at once. In the event of the building fire alarm sounding evacuate areas immediately. Ensure they are secure on exit. Experimental samples spilled or dropped in the vicinity of HASS sources. These must be dealt with by the appropriate procedures. Procedures should be detailed in the relevant risk assessments, so ensure you are familiar with these before working in the area. Radiation Monitor Equipment 4 In all circumstances, do not attempt to continue to use the HASS source. The RPA / RPO will help by giving advice on restriction of exposure or de-contamination using appropriate radiation protection principles if necessary. Of course, the onus is on developing procedures and methods that mitigate the foreseeable incident, rather than simply provide contingency arrangements and hoping you never have to use them. Other scenarios that might be considered for typical work at the College could include: A lost radioactive source A damaged isotope package arriving at the College A fire in a laboratory A chemical reaction between a reagent and radioisotope. Ref No. IRPM-IRCP-010 Page 6 of 6 September 2015