Construction of tunnels in a deep crystalline host rock for a potential High-Level Radioactive Waste(HLW) repository inevitably generates an excavation disturbed zone (EDZ). There have been a series of debates on whether a permeability in an EDZ increases or not and what would be the maximum depth of an EDZ. Recent studies show mixed opinions on permeability. However, there has been an international consensus on the thickness of an EDZ; 30 cm for TBM and 1 meter for controlled blast. One of the impacts of an EDZ is on determining the distance between adjacent deposition holes. The void gap by the excavation hinders relaxation of temperature profiles so that the current Korean reference designing distance between holes should be stretched out more to keep the maximum temperature in a buffer region below 100 degrees Celsius. The other impact of an EDZ is on the long-term post closure radiological safety. To estimate the impact, the reference scenario, the well scenario, is chosen. Released nuclides diffuse through a bentonite buffer region experiencing strong sorption and reach a fracture surrounded by a porous medium. Inside a fractured porous region, radionuclides migrate by advection and dispersion with matrix diffusion into a porous medium. Finally, they reach a well assumed to be a source of potable water for local residents. The annual individual dose is assessed on this well scenario to find out the significance of an EDZ. A profound sensitivity study was performed, but all results show that the impact is negligible. Even though the role of an EDZ turns out to be limited on overall safety assessment, still it is worthwhile to study the chemical role of an EDZ, such as a potential source for natural colloids, potential sealing of an open fracture by fine clay particles generated by the process of an EDZ, and alteration of a sorption mechanism by an EDZ in the future.

We used three-dimensional Matrigel culture system to examine the morphognesis of normal and malignant salivary glands cell in vitro including acinar cells(AC), myoepithelial cell(MC), salivary gland adenocarcinoma cells(SGT), mucoepidermoid carcinoma cells(MEC), and immortalized human salivary gland cells(HSG). For this purpose, normal and salivary gland tumor cells cultured in 3-D Matrigel, and characterized histologically and immunohistochemically, compared with same cells grown on monolayer culture and patient tissue from biopsy. 1. In three-dimensional Matrigel culture, HSG cells form acinar structure, SGT cells shows duct like structure, and other AC, MC and MEC cells dont' form any structure , and their morphology was different from that of monolayer cells. 2. Matrigel involved cell proliferation at a similar pattern to cells on plastic monolayer cell cultures, and monolayer cell revealed higher cell viability than that of Matrigel cultured cells. 3. All salivary glands cells on Matrigel or monolayer showed strong PCNA expression, and there is no expression difference in these cells. But some cells including myoepithelial cells in normal and salivary gland tumor tissue showing PCNA lavelling, so there is PCNA expression difference among normal and tumor tissue cells. 4. Actin expression was noted in AC cells on Matrigel, were rare expressed in the other cells except in MEC cells, and was present in myoepithelial cell and ductal cells of normal gland tissue. There is actin expression difference between tissue and cultured cells . 5. S-100 immunoreaction was moderateively positive in MC cells of monolayer culture, myoepithelial cells of normal tissue and pleomorphic adenoma, all cancer cells of mucoepidermoid carcinoma tissue, but significantly decreased in all salivary cells on Matrigel. 6. TGase 2 expression was prominent in MC cells of monolayer and Matrigel cultured, in myoepithelial cells of normal gland and pleomorphic adenoma, epidermoid cells of mucoepidermopid carcioma, and strong reaction in MEC and AC cells of monolayer and Matrigel cultured. 7. Expression of CK in monolayer culture showed strong reaction to CK6 in all sailvary gland cells, and mild reaction to CK10 and CK16 for all salivary cells, CK16 and CK19 expression in monolayer culture was similar to that of Matrigel culture. 8. CK6 and CK10 expression was strongest in AC and MC cells on Matrigel, and CK 4 was negative reaction in AC, SGT, MEC cells, strong reaction in MC cells but mild in SGT cells on Matrigel. Expression of CK was rare in HSG cells compared with other salivary gland cells, CK16 was prominent in SGT cells, CK10 and CK16 showed strongest expression in MEC cells of Matrigel. 9. Monolayer culture of HSG cell shwoing strong reaction to CK6, moderate to CK19 and mild to the others CK, but 3D cultured HSG cells reveal mild expression to CK16, and rare to others CK, intercallated duct in normal gland tissue showing strong to CK19, and mild to the others Ck, so there are CK expression difference in tissue, monolayer and 3-D cultured cells. 10. Monolayer culture of MEC cells represent strong reaction to CK6, mild to other CK, 3-D cells showing increased CK expression including CK6, epidermoid cells and intermediate cells in mucoepidermoid carcinoma tissue reveal positive to CK6 and CK16, mucous cell positive to CK10 and CK19, so Matrigel showed similar CK pattern compared to mucoepidermoid carcinoma tissue rather than monolThese data indicate that the interaction of salivary gland cells with basement membrane is an important factor in salivary gland development and cytodifferentiation, so this model system will be useful to study acinar or ductal differentiation in vitro.ayer cultred.