Safety Case Development Assignment -

Task 1 - Resin Storage Facility Deterministic Safety Justification

Carry out a Deterministic Safety Justification of the Facility. This comprises elements of the course titled HAZID, Substantiation and Deterministic Safety. The key aspects of this ((i) to (v)) are highlighted in bold below.

(i) Identify CSFs and undertake CSF functional breakdowns to identify Postulated Initiating Events (PIEs). Failing to use CSF decomposition negates effective identification of PIEs and safety measures. As a guide for this assignment between 5 and 10 PIEs should be sufficient.

(ii) For each PIE identify safety measures that prevent PIEs from occurring from the existing baseline. Undertake a simple HAZOP and/or FMEA. As a guide PIEs should generally not be radiological consequences. Try to word the PIE such that it is the point where the safety function has been lost, and if nothing else were undertaken, then a radiological consequence would unfold.

(iii) Identify any protective safety measures occurring from the existing baseline. If there are no protective safety measures the PIE leads directly to the radiological consequence.

(iv) This information should be captured in a fault schedule. The performance of safety measures is the subject of substantiation. Try to estimate the effectiveness of such measures in a simple manner such as percentage likely effectiveness or probability of failure to meet the safety function. Keep this to a short sentence for each safety measure which should inform the ALARP summary (Task 3).

Relevant data can be found in Annexes A, B and D and the ONR SAPs.

Task 1 = 2000 to 3000 words/equations/calculations.

Task 2 - Probabilistic Safety Analysis

Using the guidance in Annex C and the diagrams in Annex D, undertake a PSA on Hazard number 1, 'A leak at the filling station resulting in a spray of liquid.' Produce two fault trees one with a supervisor and one without. Identify the most important events. Estimate the doses to a worker and a member of the public from this accident, justifying the values used in your calculations and giving an estimate of the uncertainty in your final values. Compare the frequencies and consequences you calculate with the relevant numerical targets in the SAPs. The results from the PSA should inform the ALARP summary (Task 3).

Task 2 = 2000 to 3000 words/equations/calculations.

Task 3 - ALARP Evaluation (using assessment results from Task 1 and Task 2)

Briefly review the ONR TAG on ALARP and write a few paragraphs and a number of bullet points on how to assess ALARP for this facility.

Based on the TAG and also the guidance which follows undertake an ALARP analysis on the facility. Discuss the risks and the key safety measures identified in Task 1. Is the existing facility ALARP? Assess the fault schedule entries against safety principles (as an example of Relevant Good Practice) and identify additional preventative/protective/mitigating safety measures (and any other measures to reduce risk), informed by your estimates of risk in Task 2. Prioritise the additional safety measures and identify those which you would implement and those which you consider not to be reasonably practicable (with explanation). Is there more that can be done and is it reasonably practicable? You need to justify why you are not doing more, as well as justifying the measures you plan to implement. If possible, quantify the risk reduction achieved by some of the measures you propose, but remember that ALARP/SFAIRP is primarily undertaken by analysis against sound safety principles and other Relevant Good Practice (RGP). A Licensee would have their own safety principles, but in this assignment use a small selection of the ONR SAPs (RGP). Think of risk as its legal interpretation; 'the possibility of danger' (i.e. also the hazard). The onus is on the Licensee to make a case that the facility is safe SFAIRP (equivalent to ALARP). This could be tested in a criminal court of law so if a case cannot be made then this needs to be clearly stated.

Again, as with all of the assignment concentrate on demonstrating an effective analysis, but not necessarily a comprehensive one.

Task 3 = 2000 to 3000 words.

Attachment:- Safety Case Development Assignment File.rar