T2K water drainage / exhaust air Yuichi Oyama (KEK) Sep-25-2014 NBI2014@Fermilab

Future Improvements for higher beam power T.Koseki in　NBI2014 このグラフは今後のビームパワー増強計画と、期待されるPOTの予想です。 赤色がビームパワーの計画で、今年にリナックのエネルギーを181MeVから400MeVに上げることで、250kW程度まで増強されます。来年には、リナックの電流を30mAから50mAまで上げることで、300kW程度まで増強される予定です。 2019年頃、MRの繰り返し時間を2.4秒から1.3秒まで短縮することで、700kWまで増強される予定です。 年間の運転時間の半分程度をニュートリノにあてると、私が定年を迎える2021年頃には、T2Kの当初の計画である9x10^21POTまで到達することができる予定です。 それに合わせて、ニュートリノビームラインでもこのようなアップグレードを予定しています。 まず、今年のメンテナンスで、電磁ホーンを3台とも新品に交換します。 また、来年、3台目のホーン電源を導入し、1ホーンに電源1台の体制にします。 また、2017年から18年には、新しい設備棟を建設し、電源室とDPタンクを増設したいと考えています。 また、2014年度より、反ニュートリノの実験も始めようを思っています。 If the budget is funded timely, 750kW beam will be delivered in JFY 2017. Upgrade plans of accelerators after 750kW are still under discussion.

Overview Although some improvements are still needed, present water drainage procedure and air exhaust system are possible to accept ~750kW beam power. See talks in NBI2012 workshop. http://indico.cern.ch/event/193710/session/14/contribution/56 for water drainage talk by Y.Oyama, and http://indico.cern.ch/event/193710/session/14/contribution/57 for exhaust air talk by T.Ishida. In this talk, progress in recent 2 years are reported. Future upgrade plans aiming at ~2MW beam operation are also presented.

Water Drainage

Cooling water systems in T2K neutrino beam line BD cooling water system TS cooling water system （DV downstream and BD,10.0m3） （TS and DV upstream, 7.8m3） Horn cooling water system (2.7m3) 3 independent cooling water systems. Horn and TS cooling water are disposed from facilities in an upstream building (NU2), and BD cooling water are disposed from downstream NU3 building. Products from Oxygen except 3H and 7Be decay within several ten minutes, or have extremely long life. Disposal scenario of only 3H (t1/2=12.3y) and 7Be (t1/2=53.3d) must be considered. Metal ions from beam-line components/pipes are resolved in water. 22Na (t1/2=2.6y), from Aluminum must be considered.

Horn cooling water system (2.7m3) TS/DV cooling water system (7.8m3) Disposal Scenario of Radioactive Cooling Water in the Target Station n beam 1 month Target Station (off-limits) Until 7Be removed satisfactory 3 days/cycle a few days ~ 10 days From 2013 maintenance clean water Ion exchangers pH control system H2SO4 NaOH clean water Horn cooling water system (2.7m3) 2011 2 Dilution tanks (42m3x 2) pH~7 pH<4 B2 tank (~4m3) Buffer tank (19.5m3) drainage TS/DV cooling water system (7.8m3) ~80% Drain tank (20.5m3) Ion exchangers 2012w Ion exchangers drain water from air-conditioner etc

Summary and Prospect for Radioactive Water Drainage FY2012 FY2013 FY201X FY202X? Beam power 3.10 x 1020pot (=149kW x 107s eqv.) 2.20 x 1020pot (=106kW x 107 sec eqv.) 15.6 x 1020pot (=750kW x 107s eqv.) 41.6 x 1020pot (=2MW x 107s eqv.) 7Be (Total) < 1200MBq per year ~180GBq  36.5MBq (by ion-exchangers) Reduction rate 99.98% ~130GBq  6.5MBq (by ion-exchangers) reduction rate > 99.99% ~920GBq  46MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed ~2500GBq  120MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed 3H < 800GBq per year (Concent.) < 60Bq/cc (< 42Bq/cc for safety) 77.6GBq (NU2) 30.0GBq(Horn) 47.6GBq(TS) 15.9GBq (NU3,BD) ----------------------------- 93.5GBq (NU2+NU3) 57.3GBq (NU2) 22.1GBq(Horn) 35.2GBq(TS) 15.1GBq (NU3,BD) ------------------------------ 73.2GBq (NU2+NU3) 390GBq (NU2) 151GBq(Horn) 239GBq(TS) 95GBq (NU3,BD) ------------------------------ 485GBq (NU2+NU3) 1040GBq (NU2) 403GBq(Horn) 637GBq(TS) 253GBq (NU3,BD) 1293GBq (NU2+NU3) Drainage and Disposal 27 times x 84m3 (NU2) and 25 times x 17m3 (NU3) 17 times x 84m3 + 3 times x 42m3 (NU2) 23 times x 17m3 (NU3) ~70 times x 84m3 (NU2) a few x 17m3 (NU3) and 12 times x ~24GBq (Tank Truck) > 100 times x ~100m3 (NU5) and Tank Truck

Summary and Prospect for Radioactive Water Drainage FY2012 FY2013 FY201X FY202X? Beam power 3.10 x 1020pot (=149kW x 107s eqv.) 2.20 x 1020pot (=106kW x 107 sec eqv.) 15.6 x 1020pot (=750kW x 107s eqv.) 41.6 x 1020pot (=2MW x 107s eqv.) 7Be (Total) < 1200MBq per year ~180GBq  36.5MBq (by ion-exchangers) Reduction rate 99.98% ~130GBq  6.5MBq (by ion-exchangers) reduction rate > 99.99% ~920GBq  46MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed ~2500GBq  120MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed 3H < 800GBq per year (Concent.) < 60Bq/cc (< 42Bq/cc for safety) 77.6GBq (NU2) 30.0GBq(Horn) 47.6GBq(TS) 15.9GBq (NU3,BD) ----------------------------- 93.5GBq (NU2+NU3) 57.3GBq (NU2) 22.1GBq(Horn) 35.2GBq(TS) 15.1GBq (NU3,BD) ------------------------------ 73.2GBq (NU2+NU3) 390GBq (NU2) 151GBq(Horn) 239GBq(TS) 95GBq (NU3,BD) ------------------------------ 485GBq (NU2+NU3) 1040GBq (NU2) 403GBq(Horn) 637GBq(TS) 253GBq (NU3,BD) 1293GBq (NU2+NU3) Drainage and Disposal 27 times x 84m3 (NU2) and 25 times x 17m3 (NU3) 17 times x 84m3 + 3 times x 42m3 (NU2) 23 times x 17m3 (NU3) ~70 times x 84m3 (NU2) a few x 17m3 (NU3) and 12 times x ~24GBq (Tank Truck) > 100 times x ~100m3 (NU5) and Tank Truck

7Be 7Be and other metal radio-nuclei can be removed by ion-exchangers. We need long circulation time to remove 7Be. For example, the volume of the buffer tank is ~20m3, and the flow rate in the ion-exchangers is ~1m3/hour. After 1 day circulation, the concentration of the radioisotopes will become only ~1/e. From 2013, the horn cooling water is circulated in the ion-exchangers in the target station even during the beam period. This improved the reduction rate drastically. In 2013, total 7Be in the drain water is only 6.5MBq, where the limit is 1200MBq. This reduction rate is satisfactory even if the beam power is upgraded to be ~2MW. Remaining problems are the lifetime and replacement of the ion-exchangers.

Y.Oyama NBI2012

Y.Oyama NBI2012 After ~5 years from the commissioning, the ion-exchangers are still alive. The lifetime of the ion-exchangers is longer than that of 22Na !

Summary and Prospect for Radioactive Water Drainage FY2012 FY2013 FY201X FY202X? Beam power 3.10 x 1020pot (=149kW x 107s eqv.) 2.20 x 1020pot (=106kW x 107 sec eqv.) 15.6 x 1020pot (=750kW x 107s eqv.) 41.6 x 1020pot (=2MW x 107s eqv.) 7Be (Total) < 1200MBq per year ~180GBq  36.5MBq (by ion-exchangers) Reduction rate 99.98% ~130GBq  6.5MBq (by ion-exchangers) reduction rate > 99.99% ~920GBq  46MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed ~2500GBq  120MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed 3H < 800GBq per year (Concent.) < 60Bq/cc (< 42Bq/cc for safety) 77.6GBq (NU2) 30.0GBq(Horn) 47.6GBq(TS) 15.9GBq (NU3,BD) ----------------------------- 93.5GBq (NU2+NU3) 57.3GBq (NU2) 22.1GBq(Horn) 35.2GBq(TS) 15.1GBq (NU3,BD) ------------------------------ 73.2GBq (NU2+NU3) 390GBq (NU2) 151GBq(Horn) 239GBq(TS) 95GBq (NU3,BD) ------------------------------ 485GBq (NU2+NU3) 1040GBq (NU2) 403GBq(Horn) 637GBq(TS) 253GBq (NU3,BD) 1293GBq (NU2+NU3) Drainage and Disposal 27 times x 84m3 (NU2) and 25 times x 17m3 (NU3) 17 times x 84m3 + 3 times x 42m3 (NU2) 23 times x 17m3 (NU3) ~70 times x 84m3 (NU2) a few x 17m3 (NU3) and 12 times x ~24GBq (Tank Truck) > 100 times x ~100m3 (NU5) and Tank Truck

 Accepting 750kW beam is not realistic ! Number of Drainages In the present drainages, we can dispose: 84m3 x 42Bq/cc = 3.53GBq in NU2 17m3 x 42Bq/cc = 0.71GBq in NU3 In FY2012, 149kWx107s beam and 27(NU2)+25(NU3) drainages. For 750kWx107s beam, 110(NU2)+130(NU3) drainages are needed. Present number of drainages are limited by: - one drainage needs 3 days for dilution, radiation measurements and drainage. Maximum number of drainages is twice per week. - Work only on business days. If facility upgrades are not assumed, the possible solutions are upgrade of the manpower. -Shorten the drainage cycle, and no weekly limit? -Work on…… …….National holidays….. ……Saturdays, …Sundays,  Accepting 750kW beam is not realistic !

Summary and Prospect for Radioactive Water Drainage FY2012 FY2013 FY201X FY202X? Beam power 3.10 x 1020pot (=149kW x 107s eqv.) 2.20 x 1020pot (=106kW x 107 sec eqv.) 15.6 x 1020pot (=750kW x 107s eqv.) 41.6 x 1020pot (=2MW x 107s eqv.) 7Be (Total) < 1200MBq per year ~180GBq  36.5MBq (by ion-exchangers) Reduction rate 99.98% ~130GBq  6.5MBq (by ion-exchangers) reduction rate > 99.99% ~920GBq  46MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed ~2500GBq  120MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed 3H < 800GBq per year (Concent.) < 60Bq/cc (< 42Bq/cc for safety) 77.6GBq (NU2) 30.0GBq(Horn) 47.6GBq(TS) 15.9GBq (NU3,BD) ----------------------------- 93.5GBq (NU2+NU3) 57.3GBq (NU2) 22.1GBq(Horn) 35.2GBq(TS) 15.1GBq (NU3,BD) ------------------------------ 73.2GBq (NU2+NU3) 390GBq (NU2) 151GBq(Horn) 239GBq(TS) 95GBq (NU3,BD) ------------------------------ 485GBq (NU2+NU3) 1040GBq (NU2) 403GBq(Horn) 637GBq(TS) 253GBq (NU3,BD) 1293GBq (NU2+NU3) Drainage and Disposal 27 times x 84m3 (NU2) and 25 times x 17m3 (NU3) 17 times x 84m3 + 3 times x 42m3 (NU2) 23 times x 17m3 (NU3) ~70 times x 84m3 (NU2) a few x 17m3 (NU3) and 12 times x ~24GBq (Tank Truck) > 100 times x ~100m3 (NU5) and Tank Truck

Tank Truck The back-end section of JAEA provides a service to take over radioactive water by a tank truck. They can dispose them in another facility. They can take over 8m3 x ~3000Bq/cc 3H by their tank truck at a time. It corresponds to ~24GBq 3H. The maximum frequency of the service is once a month. Because of the small disposal tanks in NU3, use of the tank truck service in NU3 is more effective. One tank truck can reduce more than 30 times of drainages in NU3. The first takeover by the tank truck in NU3 is planned in early next year. We may be able to negotiate about the frequency after that. About 70 drainages from NU2, a few drainages from NU3, and 12 tank truck takeovers in a year is realistic for 750kW beam.

Summary and Prospect for Radioactive Water Drainage FY2012 FY2013 FY201X FY202X? Beam power 3.10 x 1020pot (=149kW x 107s eqv.) 2.20 x 1020pot (=106kW x 107 sec eqv.) 15.6 x 1020pot (=750kW x 107s eqv.) 41.6 x 1020pot (=2MW x 107s eqv.) 7Be (Total) < 1200MBq per year ~180GBq  36.5MBq (by ion-exchangers) Reduction rate 99.98% ~130GBq  6.5MBq (by ion-exchangers) reduction rate > 99.99% ~920GBq  46MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed ~2500GBq  120MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed 3H < 800GBq per year (Concent.) < 60Bq/cc (< 42Bq/cc for safety) 77.6GBq (NU2) 30.0GBq(Horn) 47.6GBq(TS) 15.9GBq (NU3,BD) ----------------------------- 93.5GBq (NU2+NU3) 57.3GBq (NU2) 22.1GBq(Horn) 35.2GBq(TS) 15.1GBq (NU3,BD) ------------------------------ 73.2GBq (NU2+NU3) 390GBq (NU2) 151GBq(Horn) 239GBq(TS) 95GBq (NU3,BD) ------------------------------ 485GBq (NU2+NU3) 1040GBq (NU2) 403GBq(Horn) 637GBq(TS) 253GBq (NU3,BD) 1293GBq (NU2+NU3) Drainage and Disposal 27 times x 84m3 (NU2) and 25 times x 17m3 (NU3) 17 times x 84m3 + 3 times x 42m3 (NU2) 23 times x 17m3 (NU3) ~70 times x 84m3 (NU2) a few x 17m3 (NU3) and 12 times x ~24GBq (Tank Truck) > 100 times x ~100m3 (NU5) and Tank Truck

A New Building The drainage of the radioactive water is definitely limited by the capacities of the disposal tanks, 84m3 in NU2 and 17m3 in NU3. We are planning to build new facility buildings, namely NU4 and NU5, for new cooling water system, new disposal tanks and other facilities. In the primary conceptual design, we will build 6 disposal tanks, 50m3 volume each in NU5. Blank space around the neutrino beam-line is strictly limited, and this is the maximum number/volume. Since we can also use old disposal tanks in NU2, the total volume of the drainage will be improved by factor ~4. We will need ~2 years for construction, and full 1-year shutdown for the construction.

New Buildings in the neutrino beam-line Dump Primary Beam-line Extraction Point Muon Monitors 110m 280m 295km To Kamioka Main Ring Target & Horns in Target Station P p m n Decay Volume Near Neutrino Detectors RCS MLF NU5 NU4

Summary and Prospect for Radioactive Water Drainage FY2012 FY2013 FY201X FY202X? Beam power 3.10 x 1020pot (=149kW x 107s eqv.) 2.20 x 1020pot (=106kW x 107 sec eqv.) 15.6 x 1020pot (=750kW x 107s eqv.) 41.6 x 1020pot (=2MW x 107s eqv.) 7Be (Total) < 1200MBq per year ~180GBq  36.5MBq (by ion-exchangers) Reduction rate 99.98% ~130GBq  6.5MBq (by ion-exchangers) reduction rate > 99.99% ~920GBq  46MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed ~2500GBq  120MBq (by ion exchangers) *the same reduction rate as FY2013 is assumed 3H < 800GBq per year (Concent.) < 60Bq/cc (< 42Bq/cc for safety) 77.6GBq (NU2) 30.0GBq(Horn) 47.6GBq(TS) 15.9GBq (NU3,BD) ----------------------------- 93.5GBq (NU2+NU3) 57.3GBq (NU2) 22.1GBq(Horn) 35.2GBq(TS) 15.1GBq (NU3,BD) ------------------------------ 73.2GBq (NU2+NU3) 390GBq (NU2) 151GBq(Horn) 239GBq(TS) 95GBq (NU3,BD) ------------------------------ 485GBq (NU2+NU3) 1040GBq (NU2) 403GBq(Horn) 637GBq(TS) 253GBq (NU3,BD) 1293GBq (NU2+NU3) Drainage and Disposal 27 times x 84m3 (NU2) and 25 times x 17m3 (NU3) 17 times x 84m3 + 3 times x 42m3 (NU2) 23 times x 17m3 (NU3) ~70 times x 84m3 (NU2) a few x 17m3 (NU3) and 12 times x ~24GBq (Tank Truck) > 100 times x ~100m3 (NU5) and Tank Truck

Total 3H problem We have assumed that the disposal quota of 3H, 800GBq/year, means that we can dispose 3H within this limit without any special care. The total quota in J-PARC is 5000GBq/year. For ~2MW beam, we expected to borrow additional quota from other facilities. However, it was pointed out that the local government and Tokai residents must agree with the drainage even if the 3H is less than the quota. Specially, the local government addresses that why only neutrino facility must dispose such amount of 3H. The total 3H from MLF (Materials and Life Science Experimental Facility) is 1.2GBq in FY2013, much less than the neutrino facility. Persuasive explanation and tough negotiation will be needed. We will encourage MLF people to dispose much more radioactive water.

Summary : Water Drainage We will be ready for 750kW x 107sec beam by the tank truck and more frequent drainages. For ~2MW beam operation, more disposal tanks are needed. The total 3H is another serious problem.

Exhaust Air

Requirement for Exhausted Air No matter how high the radiation in the underground area is, the radiation in exhausted air from the stack should be < 0.5mBq/cc. Leakage of radioactive air through gaps Ventilation system 13000m3/h > O(1) Bq/cc in underground area

Radiation in exhaust air : Summary in NBI2012 by T.Ishida Radiation in exhausted air has been reduced by air-tightening and bypass line of the ventilation. 0.1mBq/cc at 190kW has been succeeded.

Air-tight work in Target Station Caulking between concrete shields Air-tight lamination (in future) Caulking + Air-tight sheet Protection sheet under air-tight sheet Air-tight sheet (made of the same material for balloon) The air-tightening should be done every time after moving the concrete shields for maintenance. Protection sheet (over air-tight sheet)

Bypass of Ventilation in Target Station Ventilation flow rate 13000m3/h cannot be changed Bypass line Most of the air pass through the bypass line, and ventilation rate of the ground floor reduced to be 1/10. The fraction of 41Ar (t1/2~110mins) which decay in the ground floor become ~20%  ~60% Radiation in the exhausted air become 1/3 of non-bypass mode. Further change of the bypass rate will be needed for higher beam power…

Radiation in Exhausted Air : at end of FY2013 Run ~0.3mBq/cc at stack (must be < 0.5mBq/cc. This radiation is monitored in real-time) Ventilation system 13000m3/h Negative pressure ~3mBq/cc in ground floor Leakage of radioactive air through gaps ~1000mBq/cc in machine room ~5000mBq/cc in service pit @230kW beam

Summary : Exhausted Air Careful air-tightening, including use of air-tight lamination in the future, will reduce the leakage of radiation from the underground area. In the bypass of ventilation, further change of the bypass rate will be needed for higher beam power.

Summary : Water Drainage We will be ready for 750kW x 107sec beam by the tank truck and more frequent drainages. For ~2MW beam operation, more disposal tanks are needed. The total 3H is another serious problem. Summary : Exhausted Air Careful air-tightening, including use of air-tight lamination in the future, will reduce the leakage of radiation from the underground area. In the bypass of ventilation, further change of the bypass rate will be needed for higher beam power.

End