Ganeshraj
Assume you mean Topsoe (as in Haldor Topsoe) SMR plant
10% sounds a lot, what unit load is this at?
A hydrogen unit should, when running above 75% be around 2.5 %. At turndown e.g. 40% you can reach higher numbers such as 6-8% O2.
There must be a sample position somewhere down towards the stack. Do you suspect the O2 probe to be faulty, why not replace the probe to check the result
What is the opinion of HTAS (the licensor)?