b*s
2 楼
现在的量也就相当于一次CT,而且还是在核反应堆附近。似乎没那么吓人啊。而且穿上
辐射服,吃着碘片。
辐射服,吃着碘片。
h*s
6 楼
咨询过俺家ld了
压根儿就没嘛事儿
压根儿就没嘛事儿
s*6
7 楼
已经$640million了,疯了,一天卖了一个亿。
l*e
15 楼
This data is old. Current limit in shielding design is 0.25 mrem/hr or 2.5
uSv/hr, ~10 times lower.
Also 辐射服 can only stop alpha, beta and may be very low energy gamma decay
. its purpose is mainly to stop
radiation contamination. It is useless at a reactor site when the main
contributions are from neutrons and
gammas. Intake of 300 rem or 3 Sv could cause the body to fail within a
week or two. At Chernobyle ~60 of
2000 died due to such a dosage, though i have not confirmed on this data.
【在 b*****e 的大作中提到】![](/moin_static193/solenoid/img/up.png)
: 美国这边辐射防护的安全标准是2mR/hr,大约等于0.02mSv/hr,或者叫time average
: dose
: rate TADR,在设计屏蔽墙的时候都必须满足这一点。这张图上的12mSv/hr已经是600倍
: 了。辐射
: 服能衰减外照射,但是无法避免呼吸引入的内照射。碘片只能防止甲状腺吸收I131,但
: 是其它元素比
: 如Cs137无法避免。
:
: japan-quake-radiation/0317-web-RADIATION.jpg
uSv/hr, ~10 times lower.
Also 辐射服 can only stop alpha, beta and may be very low energy gamma decay
. its purpose is mainly to stop
radiation contamination. It is useless at a reactor site when the main
contributions are from neutrons and
gammas. Intake of 300 rem or 3 Sv could cause the body to fail within a
week or two. At Chernobyle ~60 of
2000 died due to such a dosage, though i have not confirmed on this data.
【在 b*****e 的大作中提到】
![](/moin_static193/solenoid/img/up.png)
: 美国这边辐射防护的安全标准是2mR/hr,大约等于0.02mSv/hr,或者叫time average
: dose
: rate TADR,在设计屏蔽墙的时候都必须满足这一点。这张图上的12mSv/hr已经是600倍
: 了。辐射
: 服能衰减外照射,但是无法避免呼吸引入的内照射。碘片只能防止甲状腺吸收I131,但
: 是其它元素比
: 如Cs137无法避免。
:
: japan-quake-radiation/0317-web-RADIATION.jpg
b*e
16 楼
不知道你这个数据是从哪里来的,或者还是行业不一样,标准不一样。我的数据是
NCRP151的标准,
是放疗屏蔽墙设计的标准。如果象你所说的话,还得再增加一个TVL,就是大概40cm的
混凝土。如果
这样的话,全美大多数放疗机构的设计需要重新考察。防辐射服的确对高能gamma射线
作用有限。我
们估计过,医院的防辐射服,对500KeV的射线只能阻挡10%左右。
2.5
decay
a
data.
【在 l****e 的大作中提到】![](/moin_static193/solenoid/img/up.png)
: This data is old. Current limit in shielding design is 0.25 mrem/hr or 2.5
: uSv/hr, ~10 times lower.
: Also 辐射服 can only stop alpha, beta and may be very low energy gamma decay
: . its purpose is mainly to stop
: radiation contamination. It is useless at a reactor site when the main
: contributions are from neutrons and
: gammas. Intake of 300 rem or 3 Sv could cause the body to fail within a
: week or two. At Chernobyle ~60 of
: 2000 died due to such a dosage, though i have not confirmed on this data.
NCRP151的标准,
是放疗屏蔽墙设计的标准。如果象你所说的话,还得再增加一个TVL,就是大概40cm的
混凝土。如果
这样的话,全美大多数放疗机构的设计需要重新考察。防辐射服的确对高能gamma射线
作用有限。我
们估计过,医院的防辐射服,对500KeV的射线只能阻挡10%左右。
2.5
decay
a
data.
【在 l****e 的大作中提到】
![](/moin_static193/solenoid/img/up.png)
: This data is old. Current limit in shielding design is 0.25 mrem/hr or 2.5
: uSv/hr, ~10 times lower.
: Also 辐射服 can only stop alpha, beta and may be very low energy gamma decay
: . its purpose is mainly to stop
: radiation contamination. It is useless at a reactor site when the main
: contributions are from neutrons and
: gammas. Intake of 300 rem or 3 Sv could cause the body to fail within a
: week or two. At Chernobyle ~60 of
: 2000 died due to such a dosage, though i have not confirmed on this data.
l*e
17 楼
Your standard is probably for radiation worker, mine is for general public,
though it may be conservative.
NCRP's standard always falls behind ICRP, that could be another underlying
reason.
To reduce from 2 mrem/hr to 0.25 merm/hr, depending on the radiation type
and energy, if in your case just
for 500 keV x-ray, it needs only ~15 cm concrete or ~2 cm lead. of coz, if
it is designed to stop high energy
gammas, like up to 10 MeV, it may take ~ 40 cm concrete. but u can replace
it with ~ 7 cm Pb.
【在 b*****e 的大作中提到】![](/moin_static193/solenoid/img/up.png)
: 不知道你这个数据是从哪里来的,或者还是行业不一样,标准不一样。我的数据是
: NCRP151的标准,
: 是放疗屏蔽墙设计的标准。如果象你所说的话,还得再增加一个TVL,就是大概40cm的
: 混凝土。如果
: 这样的话,全美大多数放疗机构的设计需要重新考察。防辐射服的确对高能gamma射线
: 作用有限。我
: 们估计过,医院的防辐射服,对500KeV的射线只能阻挡10%左右。
:
: 2.5
: decay
though it may be conservative.
NCRP's standard always falls behind ICRP, that could be another underlying
reason.
To reduce from 2 mrem/hr to 0.25 merm/hr, depending on the radiation type
and energy, if in your case just
for 500 keV x-ray, it needs only ~15 cm concrete or ~2 cm lead. of coz, if
it is designed to stop high energy
gammas, like up to 10 MeV, it may take ~ 40 cm concrete. but u can replace
it with ~ 7 cm Pb.
【在 b*****e 的大作中提到】
![](/moin_static193/solenoid/img/up.png)
: 不知道你这个数据是从哪里来的,或者还是行业不一样,标准不一样。我的数据是
: NCRP151的标准,
: 是放疗屏蔽墙设计的标准。如果象你所说的话,还得再增加一个TVL,就是大概40cm的
: 混凝土。如果
: 这样的话,全美大多数放疗机构的设计需要重新考察。防辐射服的确对高能gamma射线
: 作用有限。我
: 们估计过,医院的防辐射服,对500KeV的射线只能阻挡10%左右。
:
: 2.5
: decay
b*e
18 楼
这个数值只是辐射屏蔽设计的指标之一,跟公众还是放射工作人员无关的。有关的是另
外一个参数,
就是NCRP里面说得设计目标,P值,分控制和非控制区域。北美这边一般都用NCRP来计
算。在设计
屏蔽时,一般都要考虑leakage和散射,而leakage一般假设就是原始能量,比如15MeV
,18MeV
等等,所以都用高能的TVL。散射的能量的确只有500keV左右,但是一般计算以后,发
现散射比
leakage少。如果少一个数量级以上,就不用考虑了。否则再加一个HVL。加铅的问题是
,铅很软,
铅很重,弄不好很容易象一滩烂泥塌下来。而且在室内会有毒性,所以要么做成三明治
一样夹在混凝
土或者钢中间,要么卯起来,裸露部分还得涂上厚厚的油漆才行,对快中子还透明,对
10MeV以上高
能机器,本身还能产生中子,最后光子挡住了,中子生成了,得不偿失。
public,
underlying
type
coz, if
replace
【在 l****e 的大作中提到】![](/moin_static193/solenoid/img/up.png)
: Your standard is probably for radiation worker, mine is for general public,
: though it may be conservative.
: NCRP's standard always falls behind ICRP, that could be another underlying
: reason.
: To reduce from 2 mrem/hr to 0.25 merm/hr, depending on the radiation type
: and energy, if in your case just
: for 500 keV x-ray, it needs only ~15 cm concrete or ~2 cm lead. of coz, if
: it is designed to stop high energy
: gammas, like up to 10 MeV, it may take ~ 40 cm concrete. but u can replace
: it with ~ 7 cm Pb.
外一个参数,
就是NCRP里面说得设计目标,P值,分控制和非控制区域。北美这边一般都用NCRP来计
算。在设计
屏蔽时,一般都要考虑leakage和散射,而leakage一般假设就是原始能量,比如15MeV
,18MeV
等等,所以都用高能的TVL。散射的能量的确只有500keV左右,但是一般计算以后,发
现散射比
leakage少。如果少一个数量级以上,就不用考虑了。否则再加一个HVL。加铅的问题是
,铅很软,
铅很重,弄不好很容易象一滩烂泥塌下来。而且在室内会有毒性,所以要么做成三明治
一样夹在混凝
土或者钢中间,要么卯起来,裸露部分还得涂上厚厚的油漆才行,对快中子还透明,对
10MeV以上高
能机器,本身还能产生中子,最后光子挡住了,中子生成了,得不偿失。
public,
underlying
type
coz, if
replace
【在 l****e 的大作中提到】
![](/moin_static193/solenoid/img/up.png)
: Your standard is probably for radiation worker, mine is for general public,
: though it may be conservative.
: NCRP's standard always falls behind ICRP, that could be another underlying
: reason.
: To reduce from 2 mrem/hr to 0.25 merm/hr, depending on the radiation type
: and energy, if in your case just
: for 500 keV x-ray, it needs only ~15 cm concrete or ~2 cm lead. of coz, if
: it is designed to stop high energy
: gammas, like up to 10 MeV, it may take ~ 40 cm concrete. but u can replace
: it with ~ 7 cm Pb.
g*r
20 楼
没看懂。但是蓝老你作为X工作者要承受常人十倍的辐射?
没有天理呀!!!!天理呀!!!!!
,
【在 l****e 的大作中提到】![](/moin_static193/solenoid/img/up.png)
: Your standard is probably for radiation worker, mine is for general public,
: though it may be conservative.
: NCRP's standard always falls behind ICRP, that could be another underlying
: reason.
: To reduce from 2 mrem/hr to 0.25 merm/hr, depending on the radiation type
: and energy, if in your case just
: for 500 keV x-ray, it needs only ~15 cm concrete or ~2 cm lead. of coz, if
: it is designed to stop high energy
: gammas, like up to 10 MeV, it may take ~ 40 cm concrete. but u can replace
: it with ~ 7 cm Pb.
没有天理呀!!!!天理呀!!!!!
,
【在 l****e 的大作中提到】
![](/moin_static193/solenoid/img/up.png)
: Your standard is probably for radiation worker, mine is for general public,
: though it may be conservative.
: NCRP's standard always falls behind ICRP, that could be another underlying
: reason.
: To reduce from 2 mrem/hr to 0.25 merm/hr, depending on the radiation type
: and energy, if in your case just
: for 500 keV x-ray, it needs only ~15 cm concrete or ~2 cm lead. of coz, if
: it is designed to stop high energy
: gammas, like up to 10 MeV, it may take ~ 40 cm concrete. but u can replace
: it with ~ 7 cm Pb.
l*e
30 楼
i am not sure in a medical facility, u use fast neutrons. i am also
surprised u use such high energy x-ray? What
is the purpose for this. Anyway in that case, u can use steel + concrete,
just high density concrete.
15MeV
【在 b*****e 的大作中提到】![](/moin_static193/solenoid/img/up.png)
: 这个数值只是辐射屏蔽设计的指标之一,跟公众还是放射工作人员无关的。有关的是另
: 外一个参数,
: 就是NCRP里面说得设计目标,P值,分控制和非控制区域。北美这边一般都用NCRP来计
: 算。在设计
: 屏蔽时,一般都要考虑leakage和散射,而leakage一般假设就是原始能量,比如15MeV
: ,18MeV
: 等等,所以都用高能的TVL。散射的能量的确只有500keV左右,但是一般计算以后,发
: 现散射比
: leakage少。如果少一个数量级以上,就不用考虑了。否则再加一个HVL。加铅的问题是
: ,铅很软,
surprised u use such high energy x-ray? What
is the purpose for this. Anyway in that case, u can use steel + concrete,
just high density concrete.
15MeV
【在 b*****e 的大作中提到】
![](/moin_static193/solenoid/img/up.png)
: 这个数值只是辐射屏蔽设计的指标之一,跟公众还是放射工作人员无关的。有关的是另
: 外一个参数,
: 就是NCRP里面说得设计目标,P值,分控制和非控制区域。北美这边一般都用NCRP来计
: 算。在设计
: 屏蔽时,一般都要考虑leakage和散射,而leakage一般假设就是原始能量,比如15MeV
: ,18MeV
: 等等,所以都用高能的TVL。散射的能量的确只有500keV左右,但是一般计算以后,发
: 现散射比
: leakage少。如果少一个数量级以上,就不用考虑了。否则再加一个HVL。加铅的问题是
: ,铅很软,
b*e
32 楼
而且不是用中子,理论上讲8mev以上就能产生中子,实际的上10mev都很少,15mev和
18mev都会产生中子。所以在设计屏蔽墙的时候,必须考虑这一点。
【在 l****e 的大作中提到】![](/moin_static193/solenoid/img/up.png)
: i am not sure in a medical facility, u use fast neutrons. i am also
: surprised u use such high energy x-ray? What
: is the purpose for this. Anyway in that case, u can use steel + concrete,
: just high density concrete.
:
: 15MeV
18mev都会产生中子。所以在设计屏蔽墙的时候,必须考虑这一点。
【在 l****e 的大作中提到】
![](/moin_static193/solenoid/img/up.png)
: i am not sure in a medical facility, u use fast neutrons. i am also
: surprised u use such high energy x-ray? What
: is the purpose for this. Anyway in that case, u can use steel + concrete,
: just high density concrete.
:
: 15MeV
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