CÁLCULO DE LAS VARIABLES QUE INTERVIENEN EN EL ANÁLISIS ESTADÍSITICO

The following recommendations are directed toward those actions that CSNI could take in the short term (2006-2007) to prevent the loss of key facilities in imminent danger of closure. To assess short-term concerns, the facilities in Section 3.1 were examined as to which ones are in danger of being shut down in the next 1-2 years. For the purposes of this report, that time period includes through year 2007. These facilities are shown in Table 4.1, by technical area, along with the issues and reactors they support. Also shown are their replacement cost, and relative ranking scores for that technical area. As can be seen from Table 4.1 there are a large number of facilities in danger of being shut down in the next 1-2 years. Discussed below, by technical area, are the short-term conclusions and recommendations for CSNI

consideration. These are based upon trying to preserve those facilities having high relative ranking and versatility that would be hard to replace, if lost.

In the thermal-hydraulics area, four facilities are in short-term danger. Two of these facilities support PWR thermal-hydraulic work (PKL and APEX). However, there are other facilities for PWR- T/H work not in short-term danger (e.g., ROSA). Thus no recommendation for short-term action is needed for PWR T/H facilities. For BWR T/H facilities, both existing large integral BWR thermal- hydraulic test facilities (PANDA and PUMA) are in danger of being closed in the next 1-2 years. These facilities are unique and expensive and at least one should be maintained to be available for supporting research related to current or future BWR safety issues. Accordingly, preservation of one integral BWR thermal-hydraulic test facility (either PANDA or PUMA) is considered essential for preserving a BWR thermal-hydraulic research infrastructure. SESAR is of the view that PANDA is the preferred facility for preservation due to its scale, replacement cost and versatility (i.e. it is useful in the severe accident as well as thermal-hydraulic area). Accordingly, CSNI action is recommended in the short term to support a co-operative research programme in PANDA. It should be noted that CSNI actions resulting from the SESAR/FAP report played a major role in the preservation of PANDA over the past 5 years.

In the severe accident area, most facilities supporting the resolution of the following safety issues for BWRs, PWRs, VVERs and ALWR are in danger in the short term:

x Pre-core melt conditions.

x Combustible gas control.

x Coolability of over-heated cores.

Based upon a review of the facilities in short-term danger, listed in Table 4-1, the group concluded that the following facilities should be preserved due to their importance to resolution of the above issues (as illustrated by their high relative ranking), replacement cost, versatility, and value in long-term infrastructure preservation.

x PHEBUS.

x QUENCH.

x MISTRA.

Each of these is discussed further below.

PHEBUS is a unique facility representing a substantial financial investment, capabilities and expertise. Due to the high cost of its operation and the long timeframe necessary to plan and conduct experiments, it is not considered practical to propose that the CSNI organise a co-operative research programme in PHEBUS. Accordingly, it is recommended that PHEBUS be treated as a special case, with the French authorities taking the lead to propose and organise a future research programme using PHEBUS. In this regard it should be noted that a PHEBUS Expert Group has been organised to assess future experimental programmes in PHEBUS in the areas of LOCA (fuel response to LOCAs) and of severe accidents (fuel degradation and fission product release and transport). Both separate affects and integral tests are included in the assessment. The recommendations from this group should provide valuable input for justifying and planning future programmes in PHEBUS.

The QUENCH facility has been used extensively in the past to investigate pre-core melt conditions in LWRs. Although it is a unique facility in near-term danger, the group has concluded that any effort to preserve it for the long term should be dependent upon identifying a future experimental programme that can provide useful information beyond what has already been done in QUENCH. Accordingly, it is recommended that QUENCH be treated as a special case, with the German

authorities taking the lead to propose a future research programme in QUENCH capable of generating useful new information. In this regard, it is also recommended that the appropriate CSNI Working Group (WGAMA) be requested to consider future uses for QUENCH and provide a recommendation to CSNI that can be factored into deliberations on the future of QUENCH.

The MISTRA facility has the capability for conducting experiments on combustible gas mixing and transport in multi-compartmental configurations with detailed instrumentation and helium as a simulant for H2. As such, it can measure 3-D effects useful for assessing 3-D analytical tools. MISTRA complements the THAI facility which uses H2 and can conduct experiments on H2 combustion and aerosol distribution. THAI is not in near-term danger and is recommended for long-term preservation (see below). Accordingly, it is recommended that CSNI take action to reserve the MISTRA facility (so as to maintain the complementary infrastructure and expertise) by organising and conducting a co-operative research programme in MISTRA.

In the other technical areas (fuels, and integrity of equipment and structures) no short-term CSNI actions are recommended (i.e., note, PHEBUS was being addressed under severe accidents).

It should be recognised that implementation of the above recommendations are dependent upon interest and commitment of the “host countries” to provide sufficient resources to attract participation of other interested parties and the ability to propose experimental programmes relevant to resolution of the issues and of interest to member countries.