Ministry of Health, Labour and Welfare

Ministry of Health, Labour and Welfare

Occupational Safety and Health Department Notification No. 0517-1
17 May 2011

To:
Directors
District Labour Bureaus

From:
Director
Occupational Safety and Health Department
Labour Standards Bureau
Ministry of Health, Labour and Welfare (official seal imprinted)

Re: “An interim policy on handling sewage treatment by-products in Fukushima Prefecture”


The Nuclear Emergency Response Headquarters has released a policy paper, “An interim policy on handling sewage treatment by-products in Fukushima Prefecture” (herein after referred to as the “Policy”) as per Annex-1. In applying the policy, the points described below should be noted, and consideration shall be given to the required actions such as controlling radiation exposure of workers in order to prevent health impairment for those workers at relevant workplaces pursuant to the Ordinance on Prevention of Ionizing Radiation Hazards (hereinafter referred to as the “Ionizing Radiation Ordinance”).


It should be noted that the same content of this notice has been sent to the Governors of Fukushima, Ibaraki and Tochigi Prefectures as per Annex-2.


Notes


  1. It shall be ensured that dewatered sewage sludge and related materials generated at the sewage treatment plant that fall under the category of radioactive materials as defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance or whose effective dose rate could exceed the limits specified in Article 3, paragraph 1 in the said Ordinance (1.3mSv per three months (2.5 μSv/h)) comply with relevant provisions in the Ionizing Radiation Ordinance.
    It should also be noted that such sludge and related materials which are defined as radioactive waste may be received at workplaces as cement raw material or base coarse material etc., and the Ionizing Radiation Ordinance may be applied to those workplaces too.

  2. In order to control radiation exposures at such workplaces where sewage sludge and related materials, defined as radioactive waste, are transported or received from sewage treatment plants, information on the radiation hazard of the transported sewage sludge etc. is required to be appropriately transmitted to the employers who transport or receive the sludge and related materials. Therefore, written instructions shall be provided to the sewage treatment plants within the jurisdiction of each district which generate sewage sludge defined as radioactive material (hereinafter referred to as “detected sewage treatment plants”) as per Annex 3 to ensure that they shall inform those employers who transport or receive such sewage sludge etc. about radionuclides, quantities, concentration and so forth in the sewage sludge and related materials.

  3. Upon receiving a request for consultation about radiation exposure control and so forth from the detected sewage treatment plants or workplaces which transport or receive sewage sludge etc., appropriate action shall be taken and, if necessary, experts shall be introduced such as occupational health consultants and persons of institutes that are qualified to carry out working environment measurements (Registration No.2).




Annex1

An interim policy on handling sewage treatment by-products in Fukushima Prefecture

12 May 2011
Nuclear Emergency Response Headquarters

Radioactivity concentration as high as 446,000 Bq/kg (total radioactivity of Cs-134 and Cs-137) has been detected from the dewatered sludge and related materials from sewage treatment plants in Fukushima Prefecture and cement and molten slug both using such dewatered sludge and related materials as shown in the attachment. In response to this fact, the following policy to handle those materials for the time being was formulated by the relevant office and ministers with advice from the Nuclear Safety Committee (NSC).


1.    Basic policy for handling dewatered sludge etc.

   Dewatered sludge and related materials from sewage treatment plants shall be handled and managed properly according to its radioactivity concentration. It is important to continue the measurement of radioactivity concentration of the sludge to know the change of the situation in order to take appropriate actions.

(1)    For the dewatered sludge with high radioactivity concentration exceeding, for example, 100,000 Bq/kg, it is desirable to reduce the sludge volume by incineration and/or melting etc. and store the treated by-products appropriately within the relevant prefecture as far as possible. Especially, the incinerated ash needs to be put into sealed containers to prevent dispersion.
(2)    Dewatered sludge or the treated by-products of incinerated and/or melted dewatered sludge (other than mentioned in 1(1) above) may be stored temporarily in the sewage treatment plant or at the controlled landfill site where sewage sludge is usually disposed of within the relevant prefecture. In this case measures shall be taken, as appropriate, against dispersion during transportation.

2.    Utilization of by-products made from dewatered sludge

  
(1)    Cement produced by recycling the dewatered sludge and related materials may be utilized, provided that the radioactive concentration can be lowered below the clearance level by controlling the radioactivity concentration of the dewatered sludge etc. or mixing with or diluting it by other raw materials. However utilization of base coarse material etc. produced using slag generated by melting the dewatered sludge will need further discussion.
 
(2)    The effect of cement which had already been produced was evaluated using cement with a radioactivity concentration (Cs-134:500 Bq/kg, Cs-137:500 Bq/kg) that corresponds to that of twice larger the highest radioactive concentration measured for the cement produced in the period from 11 March 2011 to now. The result of the evaluation based on this most severe scenario used for setting the clearance level (i.e. external exposure to residents (children) when it is used as wall material) was 362 μSv per year. This value is less than the dose limit for exposures of the public from nuclear facilities (1 mSv/y), indicating that no health hazards are likely to occur by using such cement containing radioactive materials.
 
(3)    Utilization of sewage sludge as compost (manure) shall not be conducted for the time being, because it is not possible to evaluate thoroughly various farmlands and crops in a short time.

3.    General points

  
(1)    The sewage treatment plant where there is a risk that the effective dose of external radiation might exceed the limit (1.3 mSv per three months (2.5 μSv/h)) specified in Article 3, paragraph 1 in the Ordinance on Prevention of Ionizing Radiation Hazards (MHLW Ordinance No. 41, 1972 ; hereinafter referred to as the “Ionizing Radiation Ordinance” ) or a risk that sewage sludge and related materials might fall under the category of radioactive materials defined in Article 2, paragraph 2 of the said Ordinance shall conform to relevant provisions in the said Ordinance to secure safety of the workers.

It should also be noted that, in case sewage sludge and related materials might fall under the category of radioactive materials defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance, the said Ordinance might be applied to the workplaces where sewage sludge etc. are received as raw material for cement or base coarse material.
 
(2)    Measurement of Sr-90 which is based on a different method from those for other nuclides has not been conducted for dewatered sludge so far. It is much less than 10% of the radioactivity according to the results of environment monitoring in Fukushima Prefecture. Hereafter, it is desirable to measure the radioactivity of Sr-90 in the sewage sludge too.
 
(3)    The radioactivity concentration may show daily fluctuation due to regional differences and the presence of absence of rainfall. In addition, because of its nature, there is no way for sewage treatment plant operators or cement suppliers etc. to control radioactivity concentration other than by diluting the generated sludge. The upper limit defined for the radioactivity concentration is delivered simply by applying logarithmic processing on the calculation, therefore it shall be considered the limit is a guide, meaning that, even if the measured value is higher than the limit, as long as the magnitude of the measured value is the same as that of the limit, it may be considered that radiological safety will not differ significantly. Therefore appropriate action shall be taken in the case that a radioactivity concentration higher than the guide is measured, such as calculating the radiation exposure dose.

4.    Appropriate management and disposal methods

  
(1)    When the dewatered sludge and related materials are stored temporarily at the controlled landfill site etc., the relevant prefectural or other municipal authorities need to manage the temporarily stored sludge etc. properly by measuring radioactivity concentration in groundwater and in leachate treatment water to be discharged to the environment in order to check safety (though cesium is insoluble) this includes taking measures against dispersion and by controlling access as appropriate.
 
(2)    Discussions on the administrative control period etc. for the dewatered sludge and related materials (1(2) in the above) stored temporarily at the controlled landfill site and the disposal method of the sludge etc. subjected to volume reduction and stored (1(1) above) will be continued.

When radioactivity concentration significantly higher than that measured in the past is detected from dewatered sludge and related materials, ways to manage the sludge and related materials will be discussed again.





Annex1
Attachment  

Analysis results of radioactive nuclides in sludge

(1) Combined wastewater treatment plants

Facility name Municipality
where facilities
are located
Date of
analysis
Analysis results of nuclides in the
sludge (Bq/kg)
Remarks
Cs-134 Cs-137 sum of Cs I-131 sludge
Central Prefecture
Purification Center
Koriyama
City
30 Apr 13,000 13,400 28,400 --- melted slag
30 Apr 165,000 169,000 334,000 ---
Horikawa Town
Wastewater Treatment
Plant
Fukushimaa
City
2 May 158,000 168,000 328,000 5,440
4 May 216,000 230,000 446,000 6,160
Yokozuka Treatment Plant Koriyamaa
City
3 May 7,850 8,280 16,100 96 sludge collected on 2 May
3 May 3,720 3,940 7,650 89 sludge collected on 25 Apr
Haramachi Daiichi Sewage Treatment Plant Minamisomaa
City
2 May 4,560 4,820 9,380 92
Northern Purification Center Iwakia City 2 May 3,470 3,690 7,160 2,730
Eastern Purification Center Iwakia City 2 May 1,040 1,090 2,130 477

(2) Separated wastewater treatment plants

Facility name
Municipality where facilities are located
Date of analysis
Analysis results of nuclides in the sludge (Bq/kg)
Remarks
Cs-134 Cs-137 sum of Cs I-131 sludge
North Prefecture
Purification Center
Kunimi
Town
2 May 1,430 1,470 2,900 400
Adatara Seiryu Center Nihonmatsu
City
4 May 1,300 1,390 2,690 90
Hayama Seiryu Center Sukagawa
City
3 May ND ND ND ND sludge generated between Sep 2010 to 9 Apr 2011
3 May 79 85 164 25 sludge generated between 10 Apr 2010 to 2 May 2011
Ootakinemizu
Environment Center
Tamura
City
4 May 769 798 1,570 322
Shirakawa Urban
Environment Center
Shirakawa
City
2 May 813 812 1,630 48
Nishigo Village
Oodaira Purification
Center
Nishigo
Village
3 May 168 186 352 ND
Aizuwakamatsu City
Purification Plant
Aizuwakamatsu
City
3 May 1,280 1,330 2,610 61 sludge immediately after dewatering
3 May 8,500 9,230 17,700 298 sludge with chaff ripening outdoors long before the nuclear power plant accident
Kitakata Purification
Center
Kitakata
City
3 May 575 531 1,110 304
Taijima Urban
Environment Center
Minamiaizu
Town
3 May 25 37 61 ND
Central Purification
Center
Iwaki
City
3 May 857 898 1,750 448 sludge
35,700 36,800 72,500 339 soot and dust *
17,400 18,300 35,700 215 cinder generated after the nuclear power plant accident
ND ND ND ND cinder generated before the nuclear power plant accident *

* These were generated by incinerating sludge from the four wastewater treatment plants (Eastern, Northern, Southern and Central) in Iwaki City.
ND: not detected


Results of radionuclide analysis for airborne dust

(1) Combined wastewater treatment plants

Facility name Municipality
where facilities
are located
Date of
analysis
Analysis results of nuclides in airborne dust
(Bq/m3)
measurement point Cs-134 Cs-137 I-131
Horikawa Town
Wastewater
Treatment Plant
Fukushima City 2 May windward ND ND ND
downwind ND ND ND
4 May windward ND ND ND
downwind ND ND ND
Yokozuka Treatment Plant Koriyama City 3 May windward ND ND ND
downwind ND ND ND
Haramachi Daiichi
Sewage Treatment
Plant
Minamisoma City 2 May windward ND ND ND
downwind ND 0.721 ND
Northern Purification Center Iwaki City 2 May windward ND ND ND
downwind ND ND ND
Eastern Purification Center Iwaki City 2 May windward ND ND ND
downwind ND ND ND

ND: not detected


(2) Separated wastewater treatment plants

Facility name Municipality
where facilities
are located
Date of
analysis
Analysis results of nuclides in airborne dust
(Bq/m3)
measurement point Cs-134 Cs-137 I-131
North Prefecture
Purification Center
Kunimi Town 2 May windward ND ND ND
downwind ND ND ND
Adatara Seiryu Center Nihonmatsu City 4 May windward ND ND ND
downwind ND ND ND
Hayama Seiryu Center Sukagawa City 3 May windward ND ND ND
downwind ND ND ND
Ootakinemizu
Environment Center
Tamura City 4 May windward ND ND ND
downwind ND ND ND
Shirakawa Urban Environment Center Shirakawa City 2 May windward ND 0.922 ND
downwind ND 0.698 ND
Nishigo Village Oodaira Purification Center Nishigo Village 3 May windward ND ND ND
downwind ND ND ND
Aizuwakamatsu City
Purification Plant
Aizuwaka-
matsu City
3 May within the site ND ND ND
Kitakata Purification Center Kitakata City 3 May within the site ND ND ND
Tajima Urban Environment Center Minamiaizu City 3 May windward ND ND ND
downwind ND ND ND
Central Purification Center Iwaki City 3 May windward ND ND ND
downwind ND ND ND

*There is only one measurement point each for the Aizuwakamatsu City Purification Plant and the Kitakata Purification Center.
ND: not detected


(3) Rural community wastewater treatment facilities*

Facility name Municipality
where facilities
are located
Date of
analysis
Analysis results of nuclides in airborne dust
(Bq/m3)
measurement point Cs-134 Cs-137 I-131
Tamanoi Daini Otama Village 4 May windward ND ND ND
downwind ND ND ND
Motonuma Shirakawa
City
2 May windward ND 0.643 ND
downwind ND ND ND
Habuto Nishigo Village 3 May windward ND ND ND
downwind ND ND ND
Tokorozawa Yanaizu Town 4 May windward ND ND ND
downwind ND ND ND

* No analysis of radionuclides in airborne dust was undertaken because no sludge was sampled at the three facilities (Furumachi (Minamiaizu Town), Kinosaki (Sukagawa City) and Kusano (Iitate Village)).





Annex-2

Occupational Safety and Health Department Notification No.0517-2
17 May 2011

To:
Governor of Fukushima Prefecture
Governor of Ibaraki Prefecture
Governor of Tochigi Prefecture

From:
Director
Occupational Safety and Health Department
Labour Standards Bureau
Ministry of Health, Labour and Welfare

Re: “An interim policy on handling sewage treatment by-products in Fukushima Prefecture”

In response to the accident at the Fukushima Daiichi Nuclear Power Plant associated with the Great East Japan Earthquake, the Nuclear Emergency Response Headquarters released a policy paper, “ An interim policy on handling sewage treatment by-products in Fukushima Prefecture” on 12 May 2011, as per the Annex-1.

Based on this policy, it has been decided to apply the Ordinance on Prevention of Ionizing Radiation Hazards (hereinafter referred to as the “Ionizing Radiation Ordinance”) in assigning workers handling by-products from sewage treatment as described below. The contents and actions in this notification shall be made known to all the municipalities within each prefecture respectively.


Note


  1. It shall be ensured that sewage sludge and related materials generated at the sewage treatment plant that falls under the category of radioactive material as defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance or whose effective dose rate could exceed the limits specified in Article 3, paragraph 1 in the said Ordinance (1.3mSv per three months (2.5 μSv/h)) complies with relevant provisions in the Ionizing Radiation Ordinance.
    It should also be noted that such sludge and related materials which is defined as radioactive waste may be received at workplaces as raw material for cement or base coarse material etc., the Ionizing Radiation Ordinance may be applied to those workplaces too.

  2. In order to control radiation exposures at such workplaces where sewage sludge and related materials defined as radioactive waste, are transported or received from sewage treatment plants, information on the radiation hazard of the transported sewage sludge , is required to be appropriately transmitted to the employers who transport or receive the sludge and related materials. Therefore, written instructions shall be provided to the sewage treatment plants which generate sewage sludge defined as radioactive material that they shall inform those employers who transport or receive such sewage sludge etc. about radionuclides, quantities, concentration and so forth in the sewage sludge etc.




Annex-3

Sewage treatment plants that generate sewage sludge and related materials falling under the provisions in Article 2, paragraph 2 of the Ionizing Radiation Ordinance

(Note)    The information shown below is the data publicized as of the day when the notification was issued, and therefore new information may become available in the future. It is advised that attention be paid to future announcements from the sewage treatment plants within each prefectural jurisdiction. In addition, it shall be noted that cement plants which receive sewage sludge might be located outside of Fukushima Prefecture.

Fukushima Prefecture

Facility name Municipality
where facilities
are located
Date of
analysis
Analysis results of radionuclides in sludge
(Bq/kg)
Remarks
Cs-134 Cs-137 sum of Cs I-131
Central Prefecture
Purification Center
Koriyama City 30 Apr 13,000 13,400 26,400 --- sludge
30 Apr 165,000 169,000 334,000 --- molten slag
Horikawa Town Wastewater Treatment Plant Fukushima City 2 May 158,000 168,000 326,000 5,440
4 May 216,000 230,000 446,000 6,160
Yokozuka Treatment Plant Koriyama City 3 May 7,860 8,280 16,100 96 sludge sampled on 2 May
3 May 3,720 3,940 7,660 69 sludge sampled on 25 Apr
Aizuwakamatsu City
Purification Plant
Aizuwakamatsu
City
3 May 1,280 1,330 2,610 61 sludge immediately after dewatering
3 May 8,500 9,230 17,700 298 sludge with chaff ripening outdoors long before the nuclear power plant accident
Central Purification Center Iwaki City 3 May 857 896 1,750 446 sludge
35,700 36,800 72,500 339 soot and dust *
17,400 18,300 35,700 215 cinder generated after the nuclear power plant accident *
ND ND ND ND cinder generated before the nuclear power plant accident *

* Those were generated by incinerating sludge from the four wastewater treatment plants (Eastern, Northern, Southern and Central) in Iwaki City
ND: not detected




Tochigi Prefecture

Facility name Date of sampling Type of sample Total of Cs-134
and Cs-137
(Bq/kg)
Sewage Resourcing Plant
(Mobara, Utsunomiya City)
2 May incinerated ash 32,000



Ibaraki Prefecture

Facility name Date of sampling Type of sample Radioactivity (Bq/kg)
      Radioactive
Iodine
Radioactive
cesium
Naka-Kuji Purification Center 3 May dewatered sludge 290 493
3 May incinerated ash 120 17,020

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