Shielding requirements for the baseline bunker shielding (current CATIA version ) Günter Muhrer www.europeanspallationsource.se

Shielding and activation requirement (baseline, as in CATIA) The inner ceiling height of the roof, excluding frames, shall be at least 170 cm above target center (TCS). The frame height shall be at least 150 cm above target centre. Based on input from NSS, CF designed the CF floor so that the bunker wall can start at a) 11.5 m, and b) 24.5 m from the origin of the target coordinate system (TCS). [ESS-0003382, ESS-0052649]. The dose in the freely accessible part of the instrument halls shall not exceed 3 mSv/h. The top of the bunker roof shall not be freely accessible. The instruments shall have free choice of optics inside the bunker with the following restrictions: Baseline : The maximum cross-section of the opening inside the monolith structure for the purpose of the neutronics design of the bunker shielding shall be 80 cm2. If an instrument (ESTIA) exceeds this requirement, it shall be the responsibility of the instrument team to proof compliance with this requirement. The NSS dose budget for the dose to the reference person at the site boundary, as stated in version 5 of the General Safety Objectives (GSO) [ESS-0000004], which was submitted to SSM with the 2nd application, is 5 mSv/year.

Shielding and activation requirement (baseline, as in CATIA) The physical access to the bunker shall be subdivided into two zones: an area inside R11.5 (inner side of the short wall and closer to the TCS) and an area outside R11.5. (The number is provisional, but can be used for the design, until NSS finalizes the distance.) The area outside R11.5 shall be physically accessible 1 day after beam shutdown as an unrestricted controlled area. (The number is provisional, but can be used for the design, until NSS finalizes the distance.) For the area inside R11.5, routine physical access is not envisioned, but occasional access may be necessary. In order to allow for this, the front part of the bunker shall be accessible within 3 days after beam shutdown, and the whole-body dose rates shall not exceed 0.25 mSv/h (This is needs to be communicated to target division.) (The number is provisional, but can be used for the design, until NSS finalizes the distance.) The requirement that the bunker shall not emit more radiation than 5 x 104 hadrons with energy greater than 10 MeV per square meter per second, is no longer valid for the bunker design and NSS shall address this question independent of the bunker project. The instrument teams shall show that they meet the activation requirements inside the bunker. In order to streamline the work and minimize the effort, they are strongly encouraged to stay within the boundaries and best practice described in [1]. If the instrument teams want to use materials not specified in [1] they may request ESS/NOSG to perform an activation calculation for that material, which NOSG would perform at the instrument project’s expense. [1]: https://confluence.esss.lu.se/pages/viewpage.action?pageId=220725475 The instrument shall ensure that the air activation in the bunker is limited to the level that the bunker can be operated as containment class C1.