Report - Littlebrook A, B and D Power Stations

Exploring with Andy · Sep 10, 2017

Littlebrook may not be as huge as some of the stations dotted around the UK, but it's certainly much bigger than it looks from the Dartford Crossing. With the UK's fourth tallest chimney and an output of over 2 gigawatts it's certainly no baby. It pops up on here from time to time with various areas being covered individually, so here I’m aiming to bring together everything from a few visits to the site into one report, covering the entire site.

Photos are from various visits with @SpiderMonkey, A Window to yesterday and @PROJ3CTM4YH3M between 2015 - 2017.

Littlebrook C on the left, B central and A to the right

Image of all 4 power stations in the snow, as seen on display in the D station control room

Plan of the site showing the general arrangement of buildings

And an aerial view showing how the plan translates to real life

A Station

The coal-fired ‘A’ station was the first power station at Littlebrook. Built by the Kent Electric Power Company, it opened in 1939. The station was later converted to burn supplementary oil over coal, and remained in use until 1973. The station had six coal-fired boilers, 3 chain grate and 3 pulverised fuel. The steam raised in the boilers was fed to three steam receivers which in turn supplied three steam turbine generators. Two of the turbines were supplied by CA Parsons at 30 MW each driving a directly coupled air cooled alternator running at 3000 rpm. The third turbine was supplied by BTH running at 1500 rpm driving a 4-pole air cooled alternator. In its last years the 1500 4 pole alternator was decoupled from its turbine and used as a synchronous compensator thereby providing voltage regulation to its local grid.

The A station viewed from the air

One of the A station's three 30MW turbines

Facility for Reactor Engineering and Development (FRED)

The ‘A’ and ‘B’ stations had been used by Nuclear Electric, later to become BNFL as a training and development centre.

Magnox reactors were designed to be maintenance-free during their operational lifetime, however development of new techniques for working on them needed to take place before attempting new procedures on live reactors. This is where FRED came in - the Facility for Reactor Engineering and Development, where reactor inspection and repair rehearsal rigs were constructed. This is a mock-up of the reactors at Bradwell nuclear power station, used during the development of robotic equipment.

A range of mock-up nuclear reactors had been built, the ‘A’ station containing mock-ups of the reactors at Sizewell, Bradwell and Dungeness ‘A’ power stations.

Overview of the turbine hall containing the mock-up reactors

Mock-up of the reactors at Bradwell A Nuclear Power Station

Mock-up of Sizewell A reactor shell

Looking down on the Sizewell Shell

Rear of the Sizewell shell

View at the top of the rig

Some of the disused offices were suffering a lot of decay

Continued...

Exploring with Andy · Sep 10, 2017

B Station

The ‘B’ station opened between 1949 and 1950. Like the ‘A’ station, it originally burned coal, but was later converted to burn oil instead. It had a capacity of 120 MW and remained in use until 1975.

External view of the B Station's boiler house

This station featured several new concepts in power generation design; it incorporated the "unit concept" whereby boilers directly supply steam to its designated turbine-generator - previously boilers "pooled" steam via a range or receivers to any of the installed turbines. The steam cycle featured "reheat" where steam exhausting from the initial high-pressure turbine cylinder is routed back through the boiler to be reheated thereby increasing its available energy before being returned to the turbine's intermediate cylinder. Finally the 60 MW Alternator was cooled by pure hydrogen gas which has a far greater cooling effect than air. These features became common in later power station designs utilising turbine generators rated at 120 MW and over.

Staircase in the entrance hall

Looking back towards to the doors

This staircase would have led to the control room, which has now sadly been converted into bland rooms

The turbines are long gone unfortunately, and the turbine hall had been used for various activities since. Most notable were the mock-up reactors of Sizewell Nuclear Power Station that had been constructed here. More recently the mock-ups had been removed to make way for the "Exercise Unified Response" training exercise to prepare the emergency services for a large-scale disaster

The mock train disaster

Actually looks quite realistic

The turbine hall has since been cleared and is now empty

Empty turbine hall

Crane at the end of the turbine hall

The B station also contained test rigs for nuclear stations, but these have now been removed

Remains of an exhibition

The B Station boiler house

Boiler house

Another staircase in the admin block

Much of admin was flooded with light from these skylights

View of the D Station from the B stations canteen

C Station

Littlebrook C Power Station was opened between 1952 and 1956 by the Central Electricity Board, and had a total generating capacity output of 240 MW. Like the two earlier plants, it was originally coal-fired, but was converted burn fuel oil by 1958. The station continued operating until it was replaced by the D Station in 1981. This station was built in response to a rapid demand for electricity as the country emerged from austerity of the post war years. As such it utilised (a standard build) four 60 MW three cylinder non-reheat C A Parsons steam turbine generators supplied from a steam range fed by seven boilers. (The original design specified eight but the last was never built). The alternators were hydrogen cooled.

The ‘C’ station was demolished to make way for a distribution centre, so here are a few archive pictures of it...

C Station under construction

C, B and A Stations

As you can see in this aerial shot from Bing, the C Station admin block was still standing until a few years ago

D Station

Littlebrook D Station was built by the Central Electricity Generating Board from 1977 onwards with the first unit commissioned in 1981. The station was designed as a fuel oil fired station from the beginning - the diversification of fuel supplies being adopted by the CEGB in the 1970s. It incorporated the latest 660 MW, 4-cylinder re-heat design running at 3000rev/min with each turbine output therefore being larger than the combined output of the previous A, B and C station turbines. The turbine output was increased to 685 MW during commissioning with practically no additional engineering works required which is testament to the robust design standards rigorously upheld by the CEGB.

At 705ft tall, the chimney is the 4th tallest in the UK

The turbines were designed to be flexible in operation with fast responses to changes in required output. There are also 3 gas turbine units manufactured by GEC capable of 35 MW each which are capable of starting up the station should there be a complete collapse of the grid system.

Turbines

The station comprised three 660MW turbo-generator sets manufactured by GEC. The turbines are four cylinder reheat machines running at 3,000 rev/min. Each turbine has a single-flow high pressure (HP) cylinder, a double-flow intermediate pressure (IP) cylinder and two double-flow low pressure (LP) cylinders. Unit 3 had been dismantled quite some time before the closure of the station.

Turbine Schematic

Generator Schematic

Unit 1 Turbine and Generator

Unit 2 with unit 1 in the didtance

Unit 1

Units 1 and 2

Viewed from above

Low-pressure turbine blades from the now dismantled unit 3

Continued...

Exploring with Andy · Sep 10, 2017

Boilers

The boiler plant consisted of three oil fired boilers manufactured by NEI Nuclear Systems Ltd. They had an evaporation rate of 575.9kg/s at continuous maximum rating with thermal conditions of 541 deg C and 16.8 bar at the superheater outlet.