VOLCANIC HAZARD ASSESSMENT FOR CRITICAL FACILITIES: THE EXAMPLE OF THE BATAAN NUCLEAR POWER PLANT (PHILIPPINES)

As the Philippines Government asked help the International Atomic Energy Agency (IAEA) to help assess the feasibility of rehabilitating the Bataan Nuclear Power Plant, the question of the site safety with regard to volcanic hazards arises, following the statement of the Union of Concerned Scientists that the proximity of the site to the potentially active Mt. Natib volcano is a major source of concern (D'Amato and Engel, 1988).

Our analysis shows that, besides the obvious capability of Mt. Pinatubo to affect the site (BNPP experienced about 6cm of tephra fallout during the 1991 eruption of Mt. Pinatubo), both the nearby Mt. Natib and Mt. Mariveles are volcanoes capable to impact the site with a variety of volcanic phenomenon. Furthermore, we estimated the probability of an eruption of VEI 6-7 at Mt. Natib is approximately 6-9 x 10^-5 yr^-1. This yields a probability range of 2 x 10^-3 to 4 x 10^-3 for a 40 yr site performance period. Such probabilities are high compared to accepted values for many types of disruptive events at nuclear facilities.

Our conclusions show that the BNPP is within screening distances for volcanic phenomenon such as, but not restricted to, tephra fallout, pyroclastic density currents and lahars in the event of a future eruption at Mt. Natib. Mt. Mariveles and, in a lesser extent, Mt. Pinatubo are also volcanoes capable of impacting the BNPP.

Therefore, if the BNPP were to be rehabilitated, our analysis clearly indicates that the site needs a more comprehensive volcanic hazard assessment, such as the assessment the potential for new vent formation on the flanks of Mt. Natib volcano or an assessment of hazard posed by potential lava flows. Finally, we would recommend the implementation of monitoring techniques (i.e. seismic network) on both Mt. Natib and Mt. Mariveles.