An 11% plunge in Tokyo this morning on fears of a nuclear catastrophe in Japan is set to hammer London first thing Tuesday.A third explosion at the Fukushima Daiichi nuclear power plant has raised concerns of a major radiation leak. People within 30 kilometres of the plant are being told to stay indoors. The FTSE 100 looks like losing about 110 points when trading begins, according to futures prices.Over here, sales fell at Debenhams in the first half, though by a little less than forecast, and headline profit at the department store is expected to beat last year's effort and meet estimates. Like for like sales for the 26 weeks to 26 February fell 1.5% excluding VAT, but were flat including the tax. Group gross transaction value rose 3.2%. "Higher margins and the benefits of a lower interest charge helped offset the negative impact of December weather and dual running costs associated with our investment in a new distribution centre," the retailer said.A strong showing by the banking division was not enough to offset weaker performance in other parts of the business at merchant bank Close Brothers. Operating profit before tax in the six months to 31 January dipped to £55.8m from £61.8m the year before. Excluding one-of items, profit rose to £65.4m from £62m. "Given the banking division's loan book growth in the first half, it expects a good performance in the second half of the year with a modest improvement in bad debts for the financial year as a whole," it said. Security firm G4S saw profit before interest, tax and amortisation rise 4.2% in 2010 to £527m from £506m the year before. Turnover rose 4.1% to £7.4bn from £7.1bn. Organic turnover growth was 2.1%, down from a growth rate of 3.7% in 2009.