Dear Ministry for Culture and Heritage,

Nga Taonga Sound and Vision (NTSV) have stored a large quantity of Nitro-Cellulose films (Nitrate) at the Radio New Zealand AM Radio Transmission site at Whitireia Park, Titahi Bay, Wellington. In addition Archives New Zealand has leased space from NTSV to store their nitrate film collection at the same site.

Nitrate Film is a flammable/explosive hazardous substance class 4.1 = flammable solid that must be kept away from ignition sources.

The film collections are stored 520 metres from the current AM Radio Transmission mast. Soon a new mast is to be erected approximately 130 metres from the film storage location.

Radio Frequency Radiation from High Powered AM Radio Transmission stations is a known potential source of inadvertent ignition. It can create sparks when metallic objects are separated, for instance during removal of metal film can lids for inspection.

The storing of dangerous goods close to an AM Radio mast is not recommended and worldwide it has never previously been permitted. Radio New Zealand themselves recommend a safe distance from AM Radio masts to avoid problems is 1 Kilometre.

It is unknown how Wellington Regional Council as the Whitireia Park Manager and/or site owner RNZ came to approve storage of such a dangerous substance within the park.

There are three possible solutions to this problem:

1. Do nothing and just hope there is not a serious accident.
2. Relocate the AM Radio Transmission Equipment.
3. Remove the Nitrate films.

In addition to Radio Frequency Radiation there is also a danger of ignition from the indirect effects of a lightning strike to the mast. It is too risky to do nothing.

Considering the site is owned by Radio new Zealand and the National Programme AM Transmission is part of Civil Defence Critical Infrastructure, then it is very unlikely Radio Spectrum Management will instruct Radio New Zealand to reduce power/shut down then relocate their equipment elsewhere.

It is more likely NTSV will be instructed by Work Safe NZ to remove the film collection.

My question to the Ministry is will MCH be prepared to provide extra funding to NTSV for the relocation of several tons of films back to the NZ Army Ammunition Bunkers where they were previously stored?

Yours faithfully,

P L Ford

Dear Ministerial and OIA Enquiries,

Thank you for your reply. I have now received a letter from WorkSafe NZ about the storage of Nitrate Films at the Whitireia Park, Titahi Bay site. On evidence apparently supplied by Nga Taonga Sound and Vision (NTSV) plus a recent visit to the Dangerous Goods Storage Vault at Titahi Bay by an inspector, WorkSafe have concluded that the storage of the flammable Nitro-Cellulose based products owned by NTSV, Archives New Zealand and Te Papa Museum are safe and that NTSV are properly managing all risks including monitoring the state of decomposition of the Nitrate films. Obviously this means there is currently no reason for NTSV to present a case to the Ministry for relocation funding.

Unfortunately the decision by WorkSafe may not be correct. It appears they have failed to take into account the risk of inadvertent ignition from sparks caused by the site location within the strong electromagnetic field radiated from the nearby AM Radio Transmission mast. Shortly Radio New Zealand will install and energise a replacement mast considerably closer to the vault increasing this risk. There is also the possibility of damage to the vault electrical system resulting from a mast lightning strike.

Recently WorkSafe have been asked to consider the following information extracted from a symposium on the risks of Radio Frequency induced ignition:

Symposium Series NO. 154 © 2008 ABB Engineering Services
Practical Experience in Radio Frequency Induced Ignition Risk Assessment for COMAH/DSEAR compliance
Ian R Bradby, Senior Safety Consultant
ABB Engineering Services, Pavilion 9, Belasis Hall Technology Park, Billingham,
Cleveland, TS23 4YS, UK

Is your site within 30km of a radio, TV or radar transmitter? If so, radio frequency induced ignition could pose a hazard to the assets on your site. In order to comply with the Dangerous Substance and Explosive Atmosphere Regulations (DSEAR), companies handling substances capable of creating explosive atmospheres are required to carry out a formal risk assessment. This must consider the extent of foreseeable explosive atmospheres within and external to the process, and ensure that suitable equipment is installed to control all potential ignition sources. One potential ignition source arises from radio-frequency radiation, often identified during the preparation/review of company COM AH safety reports. The radio-frequency environment is becoming increasingly severe, with the proliferation of transmitting sources, increased transmitter powers and the exploitation of new techniques. Sources for radio-frequency transmissions include radio and television broadcasts, radio communications, mobile phone communications, radar and navigational equipment. These transmission sources can affect an area of up to 30km and have the potential to impinge on most operating sites. Electromagnetic waves produced by radio-frequency transmitters will induce electric currents and voltages in any conducting structure on which they impinge. The magnitude of the induced current and voltage depends upon the combination of the shape and size of the structure, the wavelength and the strength of the transmitted signal. A spark may occur if the induced voltage and currents are sufficiently large. The latest standard for the assessment of inadvertent ignition of flammable atmospheres by radio-frequency radiation, BS 6656:2002, provides detailed guidance, but currently many companies are unclear about the level of risk posed by radio-frequency induced ignition.

Radio transmissions
From Table 5 in the standard, AM radio transmissions (typical example is shown in Figure 5) can have significant vulnerable zones measured in kilometres; whereas other transmission sources, at higher frequencies, tend to have smaller zones measured in metres. Careful consideration has been given to the location of AM radio transmitter masts as listed in Table 1.

Note
The document refers to standard “BS 6656:2002”. This has since been replaced by “Assessment of Inadvertent Ignition of Flammable Atmospheres by Radio frequency Radiation Guide – PD CLC/TR 50247:2004”.

I have made an FYI OIA request for a copy of the site location compliance certificate to ascertain exactly what conditions are specified and also if WorkSafe have copies of the following two international safety documents to refer to. WorkSafe have yet to reply:

“Assessment of Inadvertent Ignition of Flammable Atmospheres by Radio frequency Radiation Guide – PD CLC/TR 50247:2004”
“Standard for the Storage and Handling of Cellulose Nitrate Film – NFPA 40”

Using the Assessment of Inadvertent ignition of Flammable Atmospheres by Radio Frequency Radiation Guide, the safe zone radius to avoid the ignition of say methane from the radiation from an AM Radio Transmission mast energised by the transmitter power levels at Titahi Bay is approximately 4 km. Unfortunately the guide makes no recommendations for flammable solids, but presumably there remains a considerable risk. Further the guide fails to provide calculation data for the situation at Titahi Bay where the vault is in the mast "near field" zone where the electromagnetic wave is still being formed and there are also strong electric and magnetic fields present. Presumably the assumption is that nobody would be foolish enough to build a dangerous goods store so close to an AM Radio mast.

WorkSafe have been given some instances of radio frequency induced events such as the sparking between drums of aviation fuel being offloaded from a ship 1 Km from a transmitter mast and the result of an incident in Australia where a builder received radio frequency burns while working 200m away from a mast energised by less than a tenth of the power levels at Titahi Bay.

NFPA-40 recommends Nitrate Films should be stored in compartments made of non-conductive material and containing no more than six cans of film in such a manner that it allows the film can lid to partially raise to release gas pressure but not come completely off. Since the vault was built this recommendation has been tightened to no more than two film cans per compartment. NFPA-40 also recommends that the only effective fire prevention method is by the installation of an automatic water deluge system.

The dangerous goods vault at Titahi Bay fails all of the above meaning there is a distinct possibility all of our pre 1950 film heritage and other valuable materials may be lost.

Hopefully WorkSafe NZ will realise they have made a serious mistake and revoke the site location compliance certificate before the RNZ replacement mast is energised. Once the certificate is revoked then NTSV will have a strong case to apply to the ministry for relocation funding.

Yours sincerely,

P L Ford