In an innocuously titled report published in January this year, the Office for Nuclear Regulation (ONR) admits that it has acceded to Sellafield’s demand to breach the current limits for the amount of highly radioactive liquid waste (HLW) it can accumulate in the site’s ageing and contentious HLW tanks. In what many will construe as being an attempt to keep the issue under the public radar, the title of the report ‘Project Assessment Report – HAL stocks specification’, which appears on ONR¡¦s website under its archived news in March, gives no hint of the breach of HLW limits that follows in the text of the report.
Whilst ONR’s report describes the breach of limit as presenting ‘a modest increase in hazard and only a slight increase in risk’, an article in the Sellafield Newsletter of December 2014 ¡V under the equally deceptive headline ‘Great progress on waste stock reduction’ describes the breach as resulting in ‘minimal hazard increase and negligible increase in risk’.
As the unwanted product of Sellafield¡¦s commercial reprocessing operations, HLW is dealt with firstly by evaporation (to reduce volume) and then, after cooling in the HLW tanks, by conversion to a solid glass form in Sellafield’s Waste Vitrification Plant WVP (see Notes on HLP and WVP). A partial loss of power accident to WVP’s Production Line 3 in November 2013 lead to the release of radioactive materials from ‘in-cell’ to working areas within WVP and resulted in the closure of the Production Line for 11 months. The loss of capacity to reduce volumes through vitrification has meant a build-up of the heat-generating and highly radioactive liquid within the storage tanks to a point where it was expected to breach the storage limit in April this year. The maximum breach is projected by ONR to occur this July with HLW levels only returning within limit in July 2016. No figures have been provided by ONR to show the extent of the breach over and above the limits.
In facilitating this breach, ONR has been swayed by Sellafield Ltd-s warning that the three alternative options to the build-up of HLW – pausing, slowing or stopping reprocessing operations in the Thermal Oxide Reprocessing Plant (THORP) – would lead to little or no benefit but result in the laying off of THORP workers ‘to accelerate other hazard and risk reduction elsewhere on the Sellafield site¡’, put additional pressure on other ageing facilities, subject the HLW tanks to increased cooling coil corrosion and, should THORP be re-started, an extension to the end of reprocessing by 2-3 years (ie from 2018 to beyond 2020).
CORE’s spokesman Martin Forwood said today: ‘The general public will be aghast that ONR has seen fit to promote increased levels of hazard and risk rather than reduce them. Confidence in the Regulator’s competence will sink to an all-time low, driven by an apparent willingness to put Sellafield’s business interests before those of health and safety. Moreover, a golden opportunity to close THORP once and for all has again been missed – a no-brainer that would have put an end to a dirty and unnecessary operation and seen its workforce put to infinitely better use in the urgent hazard reduction and clean-up work required elsewhere on site’.
The quantity of liquid HLW held in the tanks has been governed since 2001 by a series of Specifications (legal requirements) issued to Sellafield by ONR and the former Nuclear Installations Inspectorate. The 2001 Specification, with total quantities of HLW standing at around 1600 cubic metres, required the annual reduction in HLW holdings – within strict limits – to a -buffer level- of 200 cubic metres by 2015 when all reprocessing at Sellafield was then expected to have finished.
In a subsequent assessment by ONR in 2011 which took account of reprocessing continuing for a further number of years, the quantity of HLW had reduced to below 900 cubic metres and a new buffer level of 500 cubic metres set for 2015. More recent figures for current HLW holdings in cubic metres are now deemed to be commercially confidential.
ONR’s January 2014 report on the breach of limits admits that its unwillingness to enforce the current Specification leaves a gap in regulatory control of HLW at Sellafield – a gap that will now be filled with a new Operating Rule (OR). The OR will require that, over a one year period, the total quantity of liquid HLW fed into the storage tanks from reprocessing must be less than the total quantity taken out of the tanks through the process of vitrification in WVP.
CORE’s spokesman added: ‘We see two immediate and obvious dangers and weaknesses to this new rule that raise major concerns above and beyond those of the ongoing breach of HLW limits. Firstly, as confirmed in the ONR report, the Operating Rule is controlled by Sellafield and not ONR. Trusting Sellafield to comply with the Rule is like setting a discredited fox to guard the already fragile Sellafield chickens. Secondly, given its abysmal production record, any reliance on the vitrification plant to deliver the necessary goods is highly misplaced and we would have expected something with much more teeth and greater control from ONR whose tight regulation of a highly hazardous nuclear industry seems to have gone out of the window’.
Notes: From ONR’s 2011 Specification reassessment, it is understood that the unquantified current stocks of liquid HLW at Sellafield are held in 5 storage tanks built variously between 1970 and1990, each with a nominal capacity of 150 cubic metres. With the liquid HLW requiring agitation and cooling 24/7, the tanks are fitted with external cooling jackets and internal cooling coils but assorted failures to both features through wear, tear and corrosion over the years has been the focus of significant safety fears from the public and Regulator alike.
A protracted loss of coolant water to the tanks leading to the boiling and eventual explosion of the liquid HLW – the resultant radioactive plume having the potential to travel across UK and Europe – currently remains the Reference Accident for Sellafield upon which the area’s Emergency Plans are based. The HLW complex in which the storage tanks are housed has no in-built protection against commercial aircraft crash or against terrorist attack. [The HLW accident scenario is likely to be replaced this year with a Reference Accident based on a seismic event affecting a number of inter-related facilities at Sellafield]
The Waste Vitrification Plant WVP was opened in 1991 with two Production Lines which, between them, were projected to turn out 600 containers of vitrified HLW each year. Even with the subsequent addition of Production Line 3, WVP has produced at best 482 containers per year and achieved only 220 containers this last Financial Year 2014/15. The plant has missed every annual target set over the last 10 years.
Having issued an Improvement Notice to Sellafield for the WVP accident in November 2013 which resulted in the current breach of HLW limits, ONR has decided that it would not be reasonable or proportionate to take further enforcement action now over any HLW stocks specification breach.