lnvesti ation into Nuclear Safety Event 57122 ?Sim Exposure during?Trial- Haa?h Physics A?oat Manager 1. Investigation team ?eaith Physics A?oat Manager 2. References a. NP Bose):? b. NOP 402W: Establishing and maintaining an exclusion zone and controlled radiation areas onboard submarines (HMNB Clyde Faslane). c. HMNB Clyde RPSOs: Radiation Protection Standing Orders. d. Radiation protection practices onboard nuciear submarines all ships. e. 9465: Fleet naval nuclear authorisation and radiological control manual. ionising radiations regulations 1999. g- JSP 37'5: MOD Health and safety handbook. h. Raised?1248: HMNB Clyde?s Risk Assessment to clean and inspect OCT- 3. (RAM 1) (am 1 1) (sane) Monitorin Control Of?ce Team Leaders (MOO TL) ices?: amp Manager: - Ship's Staff (88) were not interviewed at time of writing the initial report due to the vessel sailing immediately after the investigation was initiated. On 16 Jan 13 a meeting was held with representatives from HMNB Clyde Assurance Department, Vessel, CGMFASFLOT, FAG, Base RPA, Base R80 and Health Physics Afloat. ?the findings from this meeting have been included within this report. 4. Event Summary 4.1 Background Towards the end of Base Maintenance Period 01, HMS-was carrying out a planned Hrial?, in conjunction with detect recti?cation on the tan the atter required 24 hour support from base staff. Both of these separate tasks were to be completed prior to the vessel departing HMNB Clyde. On 16 and Aug 12, work progressed within the?tank whilst the reactor was operating or prolonged periods. Three radiation surveys were carried between the assumption that doserates at the worksite were below ?rst therefore no controlled area was established. A further radiation survey at 21.20 on identi?ed a maximum dose rate ot?within the _lank, whilst the Immediate actions involved withdrawing all personnel from the area and informing . No further tank entries were permitted until the ?trial concluded. as the NICO TL HMS-nuclear Logic BMP 01 Issue 4 Although there was a deiay in forwarding this information to the Duty Health Physics Of?cer and Health Physics Afloat Manager, an initiai meeting was arranged at the earliest opportunity on 22 Aug 12 to discuss this incident. Attendees inciuded the BRPA, BRSO, COMFASFLOT, Assurance Department. HPAF and SSHP. This meeting lead to HMNB Clyde raising NSER.57122. 4.2 Current administrative controls 411-well: This procedure is carried out in accordance with Reference A. Although this procedure is not accompanied with a Radiologicai Protection Measures (RPM) document, specific radiation protection (RP) precautions are iisted within the procedure. The precautions include keeping personal radiation doses ALARP. the requirement for radiation surveys to be carried out on the jetty and casing at regular intervals when the?and restricting access by establishing controlled radiation areas (as required when radiation dose rates exceed 2.5 uSv- Whilst operating in?Reference enforces stringent access controi into the exclusion zonez. where personnel (excluding ship?s company) are issued with accident dosimetry3 and provided with a comprehensive brief detailing any controlied radiation areas onboard. Reference also directs ship's staff health physics (SSHP) and Engineering Support Heaith Physics (ESHP) to carry out radiation surveys and to establish controlled radiation areas (as required). There is no RPM issued with this procedure; RP precautions i actions are Hated as steps within the NOP that are required to be signed for on completion. References to are listed as additional standing orders that are applicable to both the rial and the enforcement of the exciusion zone. Contained within these references are speci?c actions that must be implemented in order to satisfy the RP requirements of a vessel operating at an Authorised Site, in addition to the mandated statutory requirements of Reference F. 4.2.2 -tanlt entry: All tank entries onboard Submarines. whilst alongside at HMNB Ciyde, are coordinated by an Authorised Person (Con?ned Spaces) in accordance with Reference (54 The risks associated with this work package were captured within Reference H. The risk assessment does not list radiation as specific hazard; it is assumed that any radiation hazard is captured under the generic risk. which is titled ?Working Onboard Vessels?. Although this risk captures a magnitude of potential risk associated with working onboard a nuclear powered submarine, the existing contrci measures specified in Reference i-i ensure that any hazards are captured by: i. The Submarines Health and Safety brief, which is given by the Quartermaster. ii. The local work site safety brief provided by the SS sponsor. The information within the risk assessment was used by the to produce the Standing Instruction Similar to the risk assessment, the Si does not specificatiy consider radiation hazards or the reactor status. The Si specifies who can access the tank, including Babcock personnei and SS (and any external contractors. where necessary). Prior to each entry into theqtank, the validity of the risk assessment and 5 were considered by those entering the tan . to ensure that the status of any ore?identi?ed risk had not 2 fixclusion zones, which consist of inside the submarine, are areas within which people would he at greatest risk in the unlikety event of a reactor emergency. Special arrangements are put in place for exclusion zones, including the provision of accident dosimetry. 3 Accident dosimetry is issued to sit non-ship?s company personnei entering an exclusion zone. It is not an acceptable substitute for occupational (approved) dosimetry; occupationai dosimetry is issued to all radiation workers at HMNB Clyde. changed and that no new risks were present. This did happen prior to each tank entry; the narrative further expiains the actions taken by 38 based on the dose rates recorded on the radiation surveys. 5. Investigation 5.1 Narrative The details of reactor plant operating history and the exposure times from the numerous tank entries, from 15 Aug 12 to 18 Aug 12. are contained within Annex A. The following is a synopsis of the incident produced from the accounts from those involved and the records obtained from the submarine. Due to the vessel sailing immediately after this incident was identi?ed, not all personnel that had a direct invotvernent have been interviewed at the time of writing this report. Prior to the?trial commencing, work had been progressing to rectify an OPDEF on the -system. During the testing phase of this recti?cation, the tank was found to be leaking. For ease of identifying key actions during this incident, each day will be reviewed in turn. 5.1.1 15 Aug 12: The reactor remained at -reiiable radiation surveys at this-indicate that alt dose rates within the?ank were below Accident dosimetry was issued to each individual entering the exclusion zone; these have been reported as being kept in the pocket of each individual throughout theirtime within the exclusion zone. The base staff do not recall their safety briefs (from the OM and onboard-sponsor) including the status of the reactor or anyr controlied radiation areas onboard. This statement applies for the following 3 days. 5.1.216 Aug 12 Prior to the night-shift entering the radiation area warning sign dose rate on the sign was is app is on area amine ia he sign up to a control a radiation area did not extend as far outboard as the- tank hatches the deck area ?designated as a controlied area is shown by the red line in the ?gure below. ank. their team leader (TL) had noted a controlled Following consuttation with his cotleague, the Ti. was made aware that the -tank formed part of the On contacting the SS engineers, SSHP and the M00 Ti. to discuss the potential etevated dose rates within the?tank, the base staff TL was advised that transiting the area ?to the worksite was permitted and that electronic dosimetry was not re uired. This decision was made on the assumption that the dose rates would be less than- inside the -ank, as the dose rates at the-ank access hatch were less than (Radiation survey CAUBSHZ refers); the figure above shows that this assumption does not account for the entire tank, as there was a controlled area established As a result of acknowledging an elevated dose rate Wit i I reac or was opera ing at power Ievet, in conjunction with the base staff TL, agreed that a radiation survey 0 tank would be carried out at the shift changewover times (0800 and 2000} and at any change in reactor power level: the latter is in agreement with the requirements of Reference B. The Iamained above-from 0400 to 2359 (and through to one on 1? Aug 12), without any repeat radiation survey carried out until 2345; the dose rates recorded on this survey commensurate with dose rates recorded when the reactor was and at therefore there is limited confidence in the validity of the data recorded in radla ion survey CA071I12. Not only has this demonstrated a lack of compliance with the agreement to survey at shift change-over times and .changesr but also poor communication and lack of thought process behween SSHP and SS engineere? ?therefore the potential for the dose rates within the tank to increase should have been considered and identified priorto permitting access. Whereas the two evolutions? were independent, communication onhoard should have identi ie a potential hazar wat is work occurring concurrently. 5.1.317 Aug t2 The concerns regarding the dose rates discussed on the (16 Aug 12) were briefed to the section manager (Sec Man). At approx. 0730, the Sec Man consulted the MEG to discuss the potentiai for elevated dose rates within the ?tank. Ail personnel within the tank were instructed to vacate, until a repeat radiation survey was carried out to assess the dose rates. Radiation survey cnorzriz was carried out at DQDD?whioh assessed the highest dose to bis?this use rate to wit to range expected? hen the reactor is shut down. SSHP recorded the-to tie-when this survey?r was carried out, giving a false indication that the results were indicative of a reactor operating Acting on this incorrect information. SS and SSHP were content for entries into the ank to continue whilst the-trial progressed; this was briefed to the base staff TL. At the night-shift change, a repeat radiation survey was carried out within th ank; all dose rates recorded were reater than The highest dose rate was recorded at the _worksite Immediately reported these findings to the DMEO and base staff TL. No further entries into the tank were permitted untii dose rates were less than_ The DMEO relayed this information to the MCC) TL. Ali further tank entries were conducted when the reactor was shutdown. 5.1.4 13 Aug 12 In an attempt to ascertain whether base staff had been inadvertently exposed to ionising radiation whilst working within the ?tank, the day-shift Ti. discussed the incident With the M00 TL. Due to lack of information available, the TL was advised to wait until Monday (20 Aug 12} to discuss this further. 5.1.5 initial actions by base staff The HPAF CPOMA was notified of this incident on 20 Aug 12 (approx. WOO), by the M00 TL. An outline of the incident was also briefed at the SFM morning meeting. The foilowing actions were taken by HPAF CPOMA: 1. Request for copies of ali radiation sowevs carried out by SSHP that related to this incident. 2. Request for a detailed iist of all iersonnel that entered the -anit during the period outlined above, from 3. Discussion hetd with the RPS onboard the submarine to determine what RP controis were in force during the?trial. The HPAF Manager was alerted to this incident on 2? Aug 12. SSHP LMA was subse uentl interviewed (the remainder of the department were unavaitabie all dayr due to# to review the radiation surveys and to discuss the RP measures taken onboar res exposure of the base staff working within the ?tank. All information was subsequently collated and discussed with the BRSO. As a ma er urgency, the meeting referred to in para 4.1 was scheduled. Consequentially, the following actions were raised: i. All accident dosimetry to be tended and dispatched to Dsti, Institute of Naval Medicine, for urgent analysis. 2. HMNB Clyde to initiate an investigation. 3. 58 to tend copies of the nuclear log sheet engineer officer of the watch log radiation survey report (81951 A) and contractor log, for the period of the rial. 4. 88 to raise NRP event. 5. is to be noti?ed of this incident. 6. Ali personnei that were identi?ed as being inadvertently exposed to ionising radiation, whilst working within the _tank, are to be noti?ed immediately (via line management and HP representative). Estimated doses are to be caiculated once investigation is com piste. DNSR to be noti?ed accordingly. 5.2 Training and Competence The senior medical branch rating has been appointed, by his Commanding Of?cer (CD), as the Radiation Protection Supervisor for ail controtied radiation areas onboard the Submarine. Although a trainee carried out radiation survey the RPS has endorsed this survey. Atso appointed by the CO, the Medicai Of?cer was fuliy quali?ed in his role as the the involvement was minimal. as he was undertaking his hand-over with the new Medina! Officer. All other personnei directly involved with this incident are considered to be suitabiy excerienced and quali?ed to meet their individual roles and responsibilities. 5.3 Documentation From the perspective of restricting exposure to the ionising radiation from the _riai, References A to provide instructions to achieve this, which include the requirement for radiation surveys and issue of personal dosimetry. This is a result of the prior risk assessment and subsequent local rates, where required) for all accessibie compartments? _tnciuuing? Neither References A or make specific comment on ensuring that compartments and tanks are checked- clear of all non-essential personnel prior to operating the reactor at controlled radiation areas when the reactor is operating at Although the references may be open to individual interpretation, this does not detract from the delegated duties and responsibilities of the RPS and EOOW in ensuring the safety of all personnel. The documentation governing work within confined spaces does not speci?cally consider the radiation hazard as a risk on its own; this risk is encapsulated within the general risks associated with work on a submarine. 6. Root Causes Poor communication has contributed greatly to this incident- This has been supplemented by a lack of understanding of the magnitude of the hazards present when operating a reactor at Although radiation surveys were carried out to identify dose rates within compartments *tailure to accurately capture the reactor PL at the time of the survey resulted in dose ra es sing interpreted incorrectly and subsequent failure in applying the appropriate RP controls mandated in the References to restrict exposure; dose rates recorded when the reactor was beiieved to be et-were subsequentiy used to permit continued access into a tank. Furthermore, the controlling documentation for entry into the _tank has failed to specificaiiy consider any potential radiation hazard. Arguabiy this could have been factored into the generic risks associated with submarines. however given the _of the _tank _it woeid be prudent to list this as a specific risk. inciusion of this risk would have - 9465. Chapter 41 Generic Fleet Prior Risk Assessments. highlighted at an early stage that a potential for .ioserates within the tank did exist. Reflecting this information on the 81 would have drawn greater attention to radiation hazards; conventionally, the focus remains on atmospheric hazards. 7. Conciusions It is apparent that the followi contra: measures have failed to suf?ciently highlight the interrelation between theatre! and the -ank work to those who needed to know. i. PAG plant state A meeting. ii. Base morning brief. Oncoard plan of todayitomorrow. iv. Nuclear procedures. v. Standing Instruction. vi. Submarine safety information board. vii. Quartennaster's brief. Local Ship's staff brief. ix. Point of work risk assessment. The following conclusions have been drawn from this investigation: 1. The base staff working within the rank were inadvertently exposed to ionising radiation, at levels of up to From the avaitable survey information. estimated doses ave een ca on a an are listed at Annex B. The maximum individual exposure is estimated at nd the estimated total exposure for personnel is 1.16 mSv. The submarine was not critical at any other time {other than the periods mentioned above} whilst work progressed within that?tank. it is therefore highly unlikely that any other inadvertent exposures occurre . 2. Preventative immediate actions by SS ensured no further inadvertent exposures occurred after the eievated dose rates were recorded at 212Dhrs on 1? Aug 12. 3. The exclusion zone and local safety briefs were not concise and failed to inforrn the base staff that the reactor was operating aim As the base staff visit the SM on a frequent basis during a BMP, their loca sa ety ne 5 the sponsor were reported to be cursory or non-existent. This was identified during the interview of those involved. The onus is placed upon both the sponsor and individuals working on the submarine to ensure that an adequate brief is delivered and received. 4. The base staff reported that they were issued with accident dosimetry for each entry into the exclusion zone. As some of the exclusion zone entry log sheets could not be located. it is not possibie to relate the dosimetry to an individual? Ati accident dosimetry has been analysed and the recorded doses are reported as being beiow the detectable threshold of 0.02 mSv. 5. 38 failed to identify the need to carry out radiation surveys within the tank on 15 .the need to assess a magni can re es Wt in an on ave een identified at an eariy stage. Applying the same controls within this tank, as are applied to other compartments Would have immediately identi?ed the uirernent to designs tan as a centre ed radiation area when operating at- This in turn would have prevented the inadvertent exposure. 5 Accident dosimetry is issued by seriai number to an individual. This data is only recorded on the exclusion zone entry tog. 10. 11. 12. The recorded PL on the radiation surveys was incorrect. Radiation survey was carried out with the understanding that the reactor-was at The reactor had been may the time this survey was carried on . he dose rates recorded were are ore I use ve ota reactor in this state and not representative of a? This survey gave a false indication of the dose rates within the?tan an erefore no ALARP measures were put in place. as it was believed that the tank was not required to be designated as a controlled radiation area. This survey was not repeated until 2120, even though the ma increased in_ This demonstrateda at: awareness or controls SSHP and repeated poor communication between the Engineers and SSHP. There is no con?dence in the dose rates recorded in survey CAOTZHZ, as they are in keeping with dose rates recorded when the reactor was Strive CA072H2 was reported as being carried out when the reactor was anew The miscommunication about the power levels, albeit of mater concern. must not distract from the fact that Babcock emptoyees were within the _tani< for more than 24 hours (0400 on 16 Aug 12 to 0715 on 1? Aug 12). with no controlled area established. no approved dosimetry and no other radiological control in place. The Tl. specifically queried the controls in place. onl to be incorrectly reassured that dose rates within the ank were less than There was prolonged and repeated failure of 38 to understand and to control the radiological hazard that they were creating. The requirement to conduct radiation surveys was not met in accordance with References A and B. Due to poor communication between the Engineers and SSHP, there was a lack of appreciation for the RP controls required during the?trial. The daily [weekly planning meetings held onboard should have prevented any work progressing within the _tank whilst the reactor was scheduled to be operating at a Initial actions by the DMEO in alerting the M00 T1. were done gaining appropriate health physics advice from the survey data available. Untortunately,tt1e potential seriousness of this incident was not relayed to the Duty Health Physics Officer at all. and subsequently. the BRSO was not informed in a timely manner. Base Has department were not informed of this incident until 24 Aug ?12. Dynamic risk assessments reviews of the worksite risk assessment and St were done prior to each tank entry. in doing so, the relevant risks that were listed on the documentation were . questioned; however there was not suf?cient consideration given to additionat (generic) risks, including the radiation hazard. Recommendations Review the documentation associated with working in tanks (con?ned spaces} onboard submarines. ?the potential for a radiation hazard must be specifically cansevent for risk assessments that are written for work that is located The AP is not SQEP to carry ou azar s; owever, a relevant con?ned spaces procedure should require him to prompt SSHP to considerthe magnitude of the radiological hazard, if any. The provision of education and training for Engineering staff (including ship?s sponsors for visitors onboard), SSHP and Quartermasters must be undertaken at the next available opportunity. This must include the importance of compiying with written procedures and statutory requirements. the issue and control of accident dosimetry {including access lists} and the requirement for applying stringent RP controls whilst operating a reactor- power tevels. References A and (and any other nuctear procedure associated with . operations alongside) are to be reviewed, with consideration given to including a statement for ensuring that all compartments (and tanks where appropriate) insiuding the _rhave been checked clear of all non-essential personnel, prior to qoperations. here should be a presumption that entry will not normally be Into these compartments and tanks. However, if there is an urgent operational requirement which justifies work within these compartments and tanks, a temporary oontrotled area should be established as required. References A and 8 contain sound guidance on carrying out surveys of the to ensure a restriction of exposure in these areas. Both of these procedures, and any other procedure associated with operating -reactor powers, would bene?t from inctuding statements to direct radiation surveys to also he canted out All activities that have radiological safety implications should be identified and deconfiicted at the appropriate planning meetings onboard. This emphasises the need to have a SSHP representative at such meetings. Consideration be given to reviewing the procedure for granting access into open tanks unheard, 0 include a statement that prohibits any tank entry opera iona imperative, access shoutd only be granted after a prior risk assessment as been conducted, meeting the requirements of ERRQQ, Reg A comprehensive estimated dose review must be carried out for each individual that was exposed to ionising radiation within the Rank, as mandated in ERRQQ. Reg 22. All personnel that were inadvertently expose must informed of their estimated doses. To ensure cooperation between emptoyers, the ?ndings of this investigation and subsequent actions by HMNB Clyde, should be communicated to NCHQ (feo and Dsti as the RPA. Communications by the NICO TL to the DHPO need to be improved. it is recommended that the M00 TL provides a brief (verbal or written) to the DHPO each morning. including weekends, to detail any occurrences over the previous 24 hours- Annex A: Narrative of Reactor Plant Operating History and ?Tank Entries 15 Aug 12: 1033: 09504035: 11154130: 1315?1351: 1315-1605: 16 Aug 12: 0001 001 5: 0400-0900: 041 5: 09004400: 0912-1030: 0912-1050: 0912-1 105: 09504050: 1342-1806: - 1 400-2359: 1 505?1000: 1 525- 1 600: 1 171 0-1 855: 1?1 0-1 81 0: 20154206: 2040-2206: 2300-2330: 2345: Aug 12: 0001 -0715: 01450715: 0500-0710: 0709-0806: 02530-0800: 0823: 0000: 09004130: 0910-1045: 0955-1120: 1106: 1245?1540: 1300-1540: 1325-1340: 1 400-2300: 1545-1730: 1545-1615: rial commenced. until 2359}. Contractor Log entry (x3) tor tank work. Contractor Log entry (x4) for tank work. Contractor Log entry (x1) for tank work. Contractor Log entry for tank work. Radiation survey (Secondary Shield Ref: Only one dose~rate recorded atFank access I on re or cg entry (x1) for Contractor Log entry (x2) for Contractor Log entry (x1) for Contractor Log entry (x1) for Contractor Log entry (x3) for ank work. ank work. ank work. ank work. ank work. nk work. ank work. ank work. ank work. ank work. Contractor Log entry (x1) for Contractor Log entry (x2) for Contractor Log entry {x2} for Contractor Log entry {x1} for Contractor Log entry (x1) for Contractor Log entry (x3) for ank work. Contractor Log entry (x4) for ank work. Radiation some of ant: (Ref: Maximum dose rate tt bottom of the access ladder into the tank. PL unrey; SSHP recorded? ank work. ank work. ank work. Contractor Log entry (x4) for Contractor Log entry (x2) for Contractor Log entry (x1) for Ra 1311011 sunre tank (Ref: Maximum dose rate 1 or level of the tank. .inoorrectly recorded on Contractor Log entry (x4) for Contractor Log entry (x1) for Contractor Log entry (x1) for Contractor Log entry (x1) for Contractor Log entry for Contractor Log entry (x1) for !ontractor Eng entry (x1) for Contractor Log entry (x1) for tank work. tank work. tank work. tank work. 1545-NK: 1550-1?30: 1640?1?30: 2110-2200: 2120: 2140-2209: 231 5-2359 2345: 18 Aug 12: 01301 41030: 0029-0345; 0045: Post 0045: ank work. ank work. arrI-t work. enk work. enk (Ref: CA074I12). Maximum dose rate t?worksite. Correct PL recorded on this Contractor Log entry (x2) for Contractor Log entry (x1) for Contractor Log entry (x2) for Contractor Log entry (x4) for Radiation survey of survey. Contractor Log entry for-ank work. Radiation some of I reco ank (Ref: Maximum dose rate at works'rte. .incoi'rectiy recorded on 3 survey; - Contractor Log entry for -tank work. Numerous ank entries were made, however there was no associated radiation exposure risk, as the otii all work was comptete. These tank entries are therefore omitted from this investigation. Annex B: Individual Estimated Doses The estimated doses are calculated using the maximum worksite dose rate of ?and tank entry times that carrelate to the information on the contractor's log. Lars-17-Aug?12 16-Aug?12 16?Aug?12 16-Aug-12 2 17-Aug-12 16-Auge12 16-Aug-12 16-Aug-12 1?-Aug-12 16~Aug-1 2 t?mAug-12 15?Aug-12 1f?Aug42 16-Aug~12 1?-Aug-12 16-Aug-1 2 17-Aug-12 16-Aug~1 2 2 1??Aug?1 2 17?Aug?1 2 17?Aug~32 17-Aug-12 CD 17-Aug?12 . --J 1T-Aug?1 2