Cracked Regulators Allow Hundreds of Cracks in Graphite Cores of Reactors across the UK


Dear Office for Nuclear Regulation

The arrogance displayed in your email reply dismissing my concerns about the running of the Hartlepool Nuclear Power Station beyond its original design life is indicative of the arrogance you display in the face of the public safety risk posed by Hartlepool, Heysham 1, Hunterston B, Hinkley Point B, and Dungeness B Nuclear Power Stations. This is very unsettling.

You constantly allow the previously agreed safety limits to be increased on graphite mass loss and cracking each time they are reached.

I draw your attention to your own document on Graphite  You are therefore well aware of the risks posed by the aging of the reactor cores. On page 8 section 5.22 you declare this

“The effects of oxidation on graphite core density for steam ingress faults should be considered in this context. Graphite weight loss will affect reactivity and—for undermoderated cores—erode margins for shutdown, hold-down and for reactivity control”

This is my key concern with the continued running of Hartlepool and its sister station at Heysham. As you know from your document these 2 stations have a known boiler design fault that is exacerbated by their prolonged running. The boilers reside inside the biological shield surrounding the nuclear reactor.

As you allow ever greater graphite mass loss to be acceptable you undermine your previously declared acceptable safety limits. I find this abhorrent in the face of the public risk

Should steam/water (which is the moderator deployed in PWR’s) enter the under moderated cores (graphite mass loss leads to the control rods having to be further removed to gain the same level of reactivity) the now over moderated cores in this scenario is where Chernobyl found itself in April 1986

You claim that Hartlepool isn’t cracking like Hunterston B

This FOI request on your site contradicts that claim




The latest date on these recorded cracks within the Hartlepool Reactors is August 2014 – more than 5 years have since passed. My concerns regarding the graphite debris, or an offset graphite brick, blocking the control rod channels, a cooling channel blockage leading to fuel melt and an undermoderated core running outside of its design life specification at Hunterston B, equally apply to Hartlepool.

I ask again that Hartlepool R2 is not restarted (Now on the 7th November) and instead the Station be shut down for good, it was originally earmarked for closure in 2009.

ONR needs to honour its mission statement

“The Office for Nuclear Regulation’s mission is to provide efficient and effective regulation of the nuclear industry, holding it to account on behalf of the public.”

With respect, your mission statement isn’t to allow the general public to be exposed to ever more nuclear risk by continually moving the safety goalposts to allow EDF to sweat its nuclear assets, with the potentially unthinkable consequences to the UK population and beyond.


David Autumns



On Mon, Nov 4, 2019 at 1:47 PM <> wrote:

Dear Mr Autumns

HPGE201910051: Return to service of Hartlepool Reactor 2

Thank you for your email of 6 October 2019 in which you raise a number of concerns regarding the return to service of Hartlepool Reactor 2 following its planned statutory outage.

Firstly I’d like to expand on ONR’s earlier comments to you regarding due process in ONR’s regulatory decisions.  It is the duty-holder’s responsibility to justify that it is safe to restart a reactor following a statutory outage. ONR has a statutory obligation to examine the evidence provided in related submissions and to make independent and objective decisions. The safety of workers and the public is our overriding priority and ONR will only permit Hartlepool Reactor 2 to return to service if we are satisfied that it is safe to do so.

Your letter states that “Like Hunterston B the radiolytic damage of the core has reduced its mass with the ONR increasing the “safety limit” from 17% to 20% to allow it to continue to run with the possibility of 23% mass loss being mooted.” You go on to claim that Hartlepool Reactor is “clearly in the same boat as Hunterston B”.

The change in graphite weight loss safety limit was agreed by ONR following our assessment of EDF’s safety case which provided an acceptable safety justification for such an increase. Any further changes in this limit would also require ONR’s agreement which would also undergo rigorous assessment by ONR.

It should also be noted that with respect to the graphite core the reactors at Hartlepool are not in the same position as those at Hunterston B. In particular, whilst there is a significant level of keyway root cracking in Hunterston B reactors, inspection of the reactors at Hartlepool has not identified any keyway root cracks. The most recent of these inspections was completed as part of the Reactor 2 statutory outage.

You highlighted the Nuclear Institute’s news piece, reporting EDF’s action arising from the (boiler spine) crack found at Heysham. Including EDF’s reported course of action to develop a safety justification and for them to present this to the Office for Nuclear Regulation (ONR) for approval.

You will be aware that ONR routinely makes its regulatory decisions, and the basis for them, a matter of public record. ONR’s detailed consideration, and regulatory decisions, in respect of the boiler spine issue, are a matter of public record and can be found at ONR’s webpages[1].

In addition, you will be aware that ONR’s decision to allow HNB Reactor 4 to restart was published on our website on 20 August 2019[2].  ONR will treat its decision regarding EDF’s request to restart Hartlepool Reactor 2 in the same way; and will publish our regulatory decision and project assessment report on our web site in due course.

Kind regards

Policy and Communications Directorate




From: David Autumns

Sent: 06 October 2019 22:56

To: Contact ONR <>; Rossi Simone <>; Goddard Andrew <>

Subject: Restarting Hartlepool Reactor 2 on the 19th October

As previously with Hunterston B I ask that Reactor 2 at Hartlepool is not restarted on the 19th October 2019

Hartlepool was due to shut down in 2009. It’s a decade later, it is tired and old as you can see, and yet you are still continuing to run it.

Within County Durham, where the station is located, there are 862,600 people. The Tyne and Wear has a population of 1.12 Million people with Newcastle just 26 miles to the North. This power station is the only one in the UK with such a dense urban population surrounding it.

Construction of the power station began 50 years ago and it eventually came online in 1983. It has been running for 36 years. MTBF reduces with age.

Like Hunterston B the radiolytic damage of the core has reduced its mass with the ONR increasing the “safety limit” from 17% to 20% to allow it to continue to run with the possibility of 23% mass loss being mooted. It is clearly in the same boat as Hunterston B with cracked shrunken graphite bricks making up the cores with all the same risks of blocked control rod holes due to graphite debris, keyway root cracking, distortion of the core impeding the movement of the control rods and the potential for the cooling CO2 being impeded by the offset core bricks leading to the possibility of fuel clad melt.

However, with Hartlepool, the situation is known to be worse.

Back in 2014, this was uncovered –

The General Public may just think that “Hey is only the boilers” but what most people are unaware of is the fact that the boilers sit inside the reactor surrounding the core that is flashing to steam 500 litres of water every second at 2500psi at over 500C  and has been doing this for 36 years. This has led to stress cracking of the boilers including the internal boiler support splines, an effect that has been seen at Hartlepool’s Sister Station, Heysham 1.

This known failure mode has the possibility of releasing high-pressure steam and water into the reactor core with a catastrophic outcome. With the loss of over 17% of the graphite moderator the reactor’s control rods have to be extracted further to keep the nuclear reaction going as the moderator speeds up the fission process by slowing down the neutrons emitted so they more effectively split the Uranium Atoms. There’s over 17% less moderator to slow down the Neutrons at Hartlepool

Were the boilers to fail, suddenly the core would be engulfed in high-pressure steam and water, which is an effective moderator, and your Hartlepool AGR turns into a PWR. The containment is built for 600psi not 2500psi. The reactivity of the core would increase and the power of the nuclear reaction would become what is euphemistically called “An Excursion”. This would happen so quickly you wouldn’t be able to insert control rods, fill the core with Nitrogen or release the boron balls.

The outcome doesn’t bear thinking about in the surrounding dense urban area …

Hartlepool was due to close down in 2009

Please, instead of restarting Reactor 2, close the Hartlepool Nuclear Power Station down today.


David Autumns

6 thoughts on “Cracked Regulators Allow Hundreds of Cracks in Graphite Cores of Reactors across the UK

  1. Pingback: Cracked Regulators Allow Hundreds of Cracks in Graphite Cores of Reactors across the UK | Mining Awareness +

  2. Stuart Hunter

    Its a shame that Mr Autumn chooses to willfully misrepresent some of the responses openly provided by the ONR. These reactors ARE safe when measured against the required standards……because the scenarios that can arise have been validated and independently examined and challenged. As in all things if you want zero risk then you cant have what you want. No buses, cars, airplanes, roads, sewer systems, hospitals etc. So please take an analytical view of the problem and of course speak up if you believe that the limits permitted on risk within society are unacceptably high. That would be a worthwhile endeavour.

  3. Pingback: Welcome to Nuclear Bristol

  4. Pingback: Issues Briefing – Hartlepool – Close Capenhurst

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