The Office for Nuclear Regulation (ONR) undertakes all regulatory interaction with the Sellafield site licensee (SellafieldLimited, SL) against a strategy defined by the ONR Sellafield Programme. That strategy includes a number of inspection plans, within which the requirement for a System Based Inspection (SBI) of the Waste Vitrification Plant (WVP) in October 2014 is identified.
The purpose of this inspection was for ONR to confirm the adequacy of implementation of those safety claims made against the HAL (Highly Active Liquor) cooling system within the WVP facility. This system was selected because of the off-site consequences that could arise in the event that this system failed to deliver its safety functions.
As part of this SBI, we examined SL’s compliance with the following licence conditions (LCs):
We carried out a two-day, on-site team inspection, delivered by the ONR WEDD site inspector, and supported by two specialists sourced from a technical support contractor.
This Safety System was judged to be adequate.
I judged, from the evidence provided, that there is a clear link between the safety case for this system, and the operating documentation and practice employed within the facility, and that the operating documentation adequately references the safety case.
I noted that the sampled Operating Rule for HAL temperature was not defined according to relevant good practice, prompting a Below Standard IIS rating for LC23. However, I judge that a combination of engineered alarms and operator actions would provide an effective response following any unplanned increase in temperature.
I saw evidence of effective adherence to operational documentation on a number of occasions during our inspection, and in some cases good practice that should be shared across the Sellafield site. I noted that sampled aspects of training arrangements were adequately implemented in accordance with the expectations of LC10 guidance, and that, with no shortfalls noted, it was appropriate to assess this area as being of a Good Standard.
I judged that all the safety mechanisms we sampled were in good working order, were appropriately controlled and maintained, and were identified within relevant plant operating documentation, as well as being physically identified on plant, where appropriate, as required by LC27 and LC28. However, I identified that, in one case, planned tests of a key indication circuit may not give the licensee the confidence in performance that it currently claims.
I judged that the plant areas we inspected are maintained to a good standard, and that plant husbandry and leak management approaches ensure that, should leaks occur, they would be identified and rectified within appropriate timescales. In terms of compliance with LC34, I consider that the system design used to detect any leaks is adequate, and is maintained sufficient to deliver its claimed performance.
From the sample inspected, I judge that the safety case for the WVP HAL Cooling sub-system has been implemented adequately. With the exception of LC23 and LC28 (for which related ONR Regulatory Issues have been either raised or updated to address the shortfalls identified here), the compliance with all inspected LC was also judged to be adequate.
My inspection noted a number of minor observations. These were shared with, and accepted by, the licensee during my inspection feedback.
I noted a number of areas of good practice within the scope of LC24 (Operating Instructions). The licensee committed to sharing these with other relevant facilities at the site.