Revision of ORE assessment for port-interfacing systems – Garching, 25.04.06Comments from EFDA Physics Integration 1

Main recommendations

Comments from EFDA Physics Integration

1. The latest reference design of the system in study should be searched and used for the assessment

2. It is important to work closely with the teams in charge of the design of the system (if possible) to assess, to make sure that the results of the assessment are representative of the system status and changes are evaluated promptly

Revision of ORE assessment for port-interfacing systems – Garching, 25.04.06Comments from EFDA Physics Integration 2

Comments from EFDA Physics Integration

1. The design of diagnostic systems is not at all sufficiently advanced to be able to accurately predict what maintenance will be required. The estimates in the report are therefore as good as any that can be made with the limited information available. However, of the 105 separate diagnostic installations a significant number will not require access or maintenance in the port cell. If the estimate for a representative diagnostic installation is appropriate, multiplying it by 105 will be an overestimation

2. Shielding (and structure) of port plugs is designed in a way that plugs meet weight limits and to be within the maximum dose rate after 11 days of shut down

3. The design of diagnostics will, if it can be justified, maximize neutron streaming to the maximum allowable level (related to possible manned access after 11 days), because:

a) for most port plugs the main neutron streaming is through the port gap, which is set by the vacuum-vessel port design and port-plug handling, on which diagnostic designers can have no influence;b) the aim is to optimize performance of the diagnostic within reasonable limits

Although this seems to be contrary to the ALARA principle, ALARA comes into play in the design of diagnostic components themselves, for example by taking measures to minimize the required manned maintenance

Diagnostics

Revision of ORE assessment for port-interfacing systems – Garching, 25.04.06Comments from EFDA Physics Integration 3

ECRH

Comments from EFDA Physics Integration

1. The design considered for the assessment is obsolete. The ECRH reference design has changed

2. The dose at the vacuum vessel closure plate is < 15Sv/h

3. In-situ replacement is foreseen for windows and ancillary systems in the port interspace

4. The work effort estimated for window replacement sounds high

5. The reduction of ECRH upper port plugs does not reduce the total number of port plugs

6. The proposal to extract the entire port plug to replace failed windows, instead of doing it with the port plug in place, does not consider the very large impact such a measure would have on machine availability and operations. It therefore seems to go against the ALARA principle because it is unreasonable. It also raises questions about the available hot-cell capacity.

Revision of ORE assessment for port-interfacing systems – Garching, 25.04.06Comments from EFDA Physics Integration 4

General comments

Comments from EFDA Physics Integration

1. The acronym ORE should be explained somewhere in the report

2. DNB is not WBS5.5

3. Any redesign that leads to lower exposure is called ALARA, whatever the reason for the redesign?

4. Some units need explanation (e.g. p-mSv/y)

5. Some conclusions are repeated many times in the report (main text, appendices, conclusions) – to ensure consistency when the document is modified, it would make sense to minimize the repetitions (especially if the repetitions are literal, instead of  given with detailed justification in one place, and summarized in the conclusions)