Spent fuel storage rack

A spent fuel storage rack that accommodates and stores spent fuels in a large number of cells formed in a grid pattern, the spent fuel storage rack comprising:

• a flat rectangular plate-shaped base that forms a bottom of the rack;
• columnar members having an L-like cross sectional shape that extend upward from four corners of the base;
• and
• at least a pair of upper and lower grid-shaped frame plates disposed above the base and fixed to and supported by inner surfaces of the columnar members, wherein
• each of the cells includes four flat plates, made of high boron content stainless steel having a boron density greater than 1%, assembled into a rectangular tube,
• the cells are arranged contiguously at fixed intervals in the grid-shaped frame plates,
• the four flat plates each include first slits and locking protrusions formed thereon,
• the locking protrusions are inserted into the first slits such that ends of each adjacent pair of the four flat plates that intersect each other at right angles,
• the locking protrusions of the ends of each adjacent pair of the four flat plates that intersect each other protrude outward by a common length beyond the intersection of the adjacent pair, and
• the locking protrusions are detachably engaged with the first slits such that, when the locking protrusions are engaged with the first slits, portions of the locking protrusions extend below the first slits and inward facing surfaces of the extended portions abut outward facing surfaces of the four flat plates below the first slits.