Ministry of Health, Labour and Welfare

Ministry of Health, Labour and Welfare

Occupational Safety and Health Department Notification No.0623 No.1
23 June 2011

To:
Directors
Districts Labour Bureau

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

Interim policy on handling water and sewage treatment by-products and disaster wastes in which radioactive substances are detected

This is to inform that the Nuclear Emergency Response Headquarters released policy papers entitled “Interim policy on handling water and sewage treatment by-products in which radioactive substances are detected” and “Issues to be noted for storage, temporary placement, and transportation of dewatered sludge and related materials,” while the Ministry of Environment released a policy paper entitled “Policy on the management of disaster waste potentially contaminated with radioactive substances” (See Annex 1 -3). This paper is based on the Ordinance on Prevention of Ionizing Radiation Hazards (hereafter referred to as “Ionizing Radiation Ordinance”) that stipulates to control radiation exposure on workers in order to protect their health. The following issues shall be noted when implementing the aforementioned policies.


It should be noted that a notification per Annex 4 was sent to the governors of Miyagi, Fukushima, Ibaraki, Tochigi, Gunma, Saitama, Chiba, Tokyo, Kanagawa, and Niigata prefectures.


Accordingly, the notification entitled “Interim policy on handling sewage treatment by-products in Fukushima Prefecture” (Occupational Safety and Health Department Notification No. 0517-1, 17 May 2011) shall be repealed by the issuance of this notification.

Notes


  1. Employers need to respect applicable provisions of the Ionizing Radiation Ordinance when dewatered sludge or its incinerated or melted form, disaster wastes or its incinerated form (hereafter referred to “dewatered sludge, etc.”), generated in the sewage treatment plants, water purification plants, incineration facilities, and waste disposal facilities (hereafter referred to as “the sewage treatment plants, etc.”) fall under the radioactive substances defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance, or when the effective dose from the dewatered sludge, etc. could potentially exceed the value specified in Article 3, paragraph 1 of the Ionizing Radiation Ordinance (1.3 mSv per three months (2.5 μSv/h)).

    In addition, the Ionizing Radiation Ordinance may also be applied to workplaces where dewatered sludge, etc. falling under the radioactive substances defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance are received as the raw materials for cement or base coarse materials.

    In case of handling dewatered sludge, etc. with a concentration level near the lower limit of the concentration of the radioactive substances specified in Article 2, paragraph 2 of the Ionizing Radiation Ordinance (about 80% of the lower limit), it is advisable for employers to measure the exposure of workers according to Article 8 and 9 of the Ionizing Radiation Ordinance.

  2. In order to control radiation exposures at such workplaces where dewatered sludge, etc. defined as radioactive substances are transported or received, information concerning hazards of the transported dewatered sludge, etc. has to be appropriately disseminated to the employers who transport or receive dewatered sludge, etc. Therefore, instructions should be provided to the sewage treatment plants within your jurisdiction that generate dewatered sludge, etc. defined as radioactive substances as per Annex-5 to ensure that they inform the employers who transport or receive such dewatered sludge, etc. concerning species, quantities, concentration, and so forth of radionuclide in the dewatered sludge, etc. to be transported in a written form.

  3. Upon requests of consultation about radiation exposure dose control and related issues from the sewage treatment plants or employers who transport or receive the dewatered sludge, etc. generated in the sewage treatment plants, the Directors of District Labour Bureau are required to take appropriate actions, and if necessary, introduce experts such as industrial health consultants and staff of the institute for measuring workplace radiation (Registration No.2).




Annex1

Interim policy on handling water and sewage treatment by-products in which radioactive substances are detected

16 June 2011
Nuclear Emergency Response Headquarters

In response to the fact that radioactive substances were detected in the dewatered sludge, etc. in the sewage treatment plants in Fukushima prefecture, a policy paper entitled “Interim policy on handling sewage treatment by-products in Fukushima Prefecture” was formulated on 12 May 2011. After the formulation of the policy, radioactive substances have also been detected in water purifying sludge and sewage sludge, etc. outside Fukushima, mainly in the east Japan. Alarmed by these incidents, discussions have been held among the offices and the ministries on the interim policy on handling water purifying sludge (including those generated in the industrial water utilities) and dewatered sludge as well as incinerated/molten dewatered sludge generated from sewage treatment plants or community sewage plants (hereafter referred to as “dewatered sludge, etc.”). Based on the polices formulated above, advices were provided by the Nuclear Safety Commission (NSC), and the policy entitled “Near term policy to ensure the safety for treating and disposing contaminated waste around the site of Fukushima Daiichi Nuclear Power Plants” (NSC, 3 June 2011) (hereafter referred to as “Safety commitment”) was compiled (See Annex 1). The results of the discussions were as follows:


1. Treatment, transportation, storage, and disposal of dewatered sludge, etc.

(1)    It is important to refer to the following principles shown in the “Safety commitment” and make every effort to reduce the radiation doses to the residents around the areas and to the workers.
(a)    The radiation exposure dose received by the residents around the areas as a consequence of the treatment, transportation, and storage shall not exceed 1 mSv/y. Special attention, such as improving the environment around the treatment facilities, needs to be paid to reduce the radiation exposure dose to the residents.
(b)    It is desirable that the radiation exposure dose of the workers engaged in the treatment, etc. will not exceed 1mSv/y, if feasible. However, during work process involving handling of materials containing a relatively high radioactivity concentration, the radiation exposure dose of the workers need to be properly controlled in accordance with the “Ordinance on Prevention of Ionizing Radiation Hazards” (Ministry of Labor Order No. 41, 1972: hereafter referred to as “Ionizing Radiation Ordinance”).
(b)    The safety of disposal shall be assessed by the “reference levels,” which are 10Sv/y or less based on the reference scenarios, or 300 Sv/y or less based on the alternative scenarios on the radiation exposure dose of the residents around the areas after the administrative control of the disposal facilities.

Based on the above principles, the dewatered sludge, etc. shall be properly managed according to the radioactivity concentration levels.


  (Incineration/melting)

(2)    Whenever possible, the volume reduction by incineration or melting shall be conducted as required, while properly ensuring implementation of the aforementioned “Safety commitment.” For example, when continuously incinerating the dewatered sludge containing a high concentration of radioactive cesium (exceeding 500,000Bq/kg as a reference level), sufficient capabilities of the dust collector should be secured in the incinerating facilities. In order to avoid dispersion, incineration ash should be properly sealed in a container.

  (Storage, etc.)

(3)    The volume of dewatered sludge, etc. shall be reduced as required and stored in water utilities, sewage treatment plants, community sewage plants, or other appropriate facilities. The points of attention when storing the dewatered sludge, etc. are shown in Annex 2.

(4)    The dewatered sludge, etc. may be temporarily placed on the burial area of the controlled type landfill sites where dewatered sludge (with no radioactivity) is usually buried, as long as the distance is maintained from the boundary of the residential area as shown in the following Table, in addition to the previously introduced measures shown above. It should be noted when the total concentration of 134Cs and 137Cs in the dewatered sludge, etc. is reduced by solidification, dilution, or other methods, the concentration shall be determined after the reduction (the same shall apply hereafter).

Table 2

1st Column 2nd Column
Target distance from the boundary A total concentration of 134Cs and 137Cs
70m 100,000 Bq/kg or less
50m 70,000 Bq/kg or less
40m 60,000 Bq/kg or less
20m 40,000 Bq/kg or less
6m 20,000 Bq/kg or less
No limit 8,000 Bq/kg or less

(5)    When the total concentration of 134Cs and 137Cs in the dewatered sludge, etc. exceeds 100,000 Bq/kg, it is desirable to store the dewatered sludge, etc. in the facilities capable of shielding radiation, located within the prefecture where the dewatered sludge has been generated.

  (Disposal)

(6)    The evaluation assuming that the dewatered sludge, etc. with a total concentration of 134Cs and 137Cs of 100,000 Bq/kg or less2 is buried in the landfill under the condition that requires a long-term measures, and this site will not be used for residential purposes in the future, indicates that radiation exposure dose received by the residents around the areas will be less than 10 μSv/y. Meanwhile, each burial site with different conditions needs a long-term administrative control as well as the discussion on the future of environmental conservation. Thus, the disposal by burial of the dewatered sludge, etc., with a total concentration of 8,000Bq/kg or less3 134Cs and 137Cs was made acceptable for the time being as long as the appropriate measures, such as creating soil layers or using waterproof materials, are taken under the condition that the site will not be used for residential purposes in the future.
The disposal by burial shall also be acceptable for the cases, where a total concentration of 134Cs and 137Cs in the dewatered sludge, etc., is below 8,000Bq/kg. The disposal sites will be used for residential or agricultural purposes in the future, or the concentration is between over 8,000 Bq/kg to below 100,000 Bq/kg, provided that the results of the evaluation conducted for each of the aforementioned cases meet the “reference level” presented in “3. Disposal” in the “Safety commitment” and the long-term management methods are acceptable4.
If dewatered sludge, etc. are disposed by the burial in the aforementioned methods, the prefectural government where the controlled type landfill sites are located should take necessary measures for monitoring and/or management of the facilities until the safety of the controlled type landfill site in the future will be ensured.
In the light of the whole concept of environmental conservation, we will continue discussion on the possibility of the dewatered sludge disposal whose total concentration of 134Cs and 137Cs is between over 8,000 Bq/kg to below 100,000 Bq/kg, in the controlled type landfill sites under the condition in which the site will not be used for residential purposes in the future without an individual assessment.

(7)    In principle, the disposal of the stored dewatered sludge, etc., by the aforementioned methods in (5) shall meet the “reference level” for the disposal presented in the “Safety commitment.” Details of the disposal methods shall be discussed further.

(8)    The employers intending to dispose the dewatered sludge, etc. shall disclose the methods of disposal by burial (if the work is commissioned to other waste disposal contractors, the methods and procedures used by contractors need to be disclosed). They shall also confirm the proper implementation of disposal and periodically report the status of implementation to the prefectural government. Upon receiving the report, the prefectural government shall make a public announcement.

(9)    If the waste disposal contractor became unable to conduct the operation, the prefectural government and the disposal suppliers of dewatered sludge, etc. should take over the responsibilities of management for the buried dewatered sludge, etc.

2.    Utilization of by-products made from dewatered sludge, etc.

(1)    Employers are allowed to distribute the recycled products made from dewatered sludge, etc., in which radioactivity are maintained below a certain level by diluting6 or adding other raw materials, if the radioactivity concentration falls below the clearance level before the employers distribute the by-products to the market.

(2)    For instance, when the cement is used as ready mixed concrete or a material for improving ground, the concentration levels will be controlled to the stage where the cement is mixed with ready mixed concrete or soil. Considering that the cement is diluted with the other ready mixed concrete or soil by a factor of two, it will be acceptable to contain the radioactivity concentration two times higher than the “clearance level” in the original cement. However, if the cement is packed and sold in the original form at general retailers, the radioactivity concentration of the cement has to be lower than the clearance level before shipping to the retail stores.

(3)    The reference evaluation methods for the use of recycled gardening soil sold as merchandise have not been established. Therefore, it is appropriate to voluntarily refrain from shipping the recycled gardening soil. After the government confirmed the safety of the recycled gardening soil in the future, the shipping of the merchandise can be resumed.

(4)    In order to make a proper utilization of by-products, it is appropriate to continue with the measurement of the radioactivity concentration in the dewatered sludge, etc. in water utilities and sewage treatment plants belonging to municipalities or community sewage plants, where a certain level of radioactivity concentration has been detected.

3.    Occupational safety and health management for workers

(1)    In order to reduce the radiation exposure dose to the lowest possible level and to achieve proper burial and utilization of by-products, the radioactivity concentration in the dewatered sludge, etc., exhaust gas at incineration/melting facilities, and discharged water from the burial site should be appropriately and periodically measured. In addition, necessary measures should be taken by concerned parties as required. The employers that discharge dewatered sludge, etc. shall record the quantities and the radioactivity concentration in the temporarily placed dewatered sludge, etc.

(2)    If there is a risk of the effective dose from external radiation at the site of sewage treatment plants, water purification plants, or waste disposal facilities to exceed the criteria(1.3mSv per three months (2.5μSv/h)), which is specified in Article 3, paragraph 1 of the Ordinance on Prevention of Ionizing Radiation Hazards (Ministry of Labor Order No. 41,1972, hereafter referred to as “Ionizing Radiation Ordinance”), or if the dewatered sludge, etc. fall under the radioactive substances defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance, applicable provisions in the Ionizing Radiation Ordinance shall be endorsed in order to ensure the safety of workers.
In addition, the Ionizing Radiation Ordinance may also be applied to workplaces where dewatered sludge, etc. falling under the radioactive substances defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance, is received as raw materials for cement or base coarse materials.
In cases when dewatered sludge, etc. with the concentration level near the minimum limit of the concentration of the radioactive substances specified in Article 2, paragraph 2 of the Ionizing Radiation Ordinance is handled, it is advisable for employers to monitor the radiation exposure dose of workers in the light of “2. Treatment, transportation, and storage” in the “Safety Commitment.”

(3)    In cases when the radiation exposure dose to workers exceed 1mSv/y, the relationship between radioactivity concentration in dewatered sludge, etc., and the radiation exposure dose of workers shall be re-evaluated, approximately 6 months after the accident, based on the radioactivity concentration detected from dewatered sludge, etc. at that time in order achieve the minimum possible levels of radiation exposure to workers.

4.    Remarks

(1)    The radioactivity concentration may fluctuate daily due to regional differences and/or climatic variables such as rainfall, etc. In addition, it is difficult for sewage management companies or cement suppliers etc., to control radioactivity concentration by the method other than diluting the generated sludge. The maximum value for radioactivity concentration is calculated simply by applying logarithmic processing on the calculation. Therefore, the maximum value should be considered as a “reference level.” This means, even if the measured value is higher than the maximum value, the extent of radiological safety risks does not vary significantly as long as the digit of measured value stays the same as that of the maximum value. Thus, appropriate action could be taken in cases when radioactivity concentration higher than the “reference” value is measured through the evaluated radiation dose by detailed calculation without relying on retrieval.

(2)    If there are any changes in circumstances, such as detection of radioactivity concentration from dewatered sludge, etc., significantly higher than the previously identified levels, the newly emerged issue might be addressed by the revision of the original principle.

1This is the result of calculation based on the evaluation of the exposure from existing wastes compiled in the light of the principles formulated by the NSC called the “Technical reviews for introducing a clearance system in the Ordinance on Prevention of Ionizing Radiation Hazards,” (Technical Reviews Working Group on Clearance, Committee on Regulation of Radiation Safety, Ministry of Education, Culture, Sports, Science and Technology, January 2010, hereafter referred to as “RI Clearance Report”).

2This is the radioactivity concentration level at which the radiation exposure dose of the residents around the areas were evaluated as 10 μSv/y or less under the condition that the site will not be used as residential properties in the future based on the “RI Clearance Report.”

4The safety of the disposal shall be evaluated based on properties, quantities, type of radioactive substances, and radioactivity concentrations of “dewatered sludge, etc.” that are finally disposed by burial (including any other materials attached or containing radioactive substances temporarily placed in the controlled type landfill sites) in addition to natural and social environments unique to the particular controlled landfill site. Furthermore, the following issues need to be verified:
a) Main operator of management and monitoring of the “dewatered sludge, etc.”
b) Requirements for administrative control in the perspective of radiation protection
c) Final soil cover depth
d) Treatment methods of radioactive substances at seepage water treatment plants
e) Conditions of site use after abolition of the final disposal site
f) Other issues needed for radiation protection
g) Measures to be implemented by prefectural governments or disposal suppliers of “dewatered sludge, etc.” in order to comply to a) to f)

5Including the measurement of radioactivity concentration of seepage water and groundwater to verify that the concentration falls below the limit, specified in the Attached Table 1 of the “Notification for establishment of the Dose Limit based on the Provisions for Fabrication of Nuclear Fuels” (STA Notice No. 13, 2000).




Annex2

Issues to be noted for storage, temporary placement and transportation of dewatered sludge and related materials

For the storage or temporary placement of dewatered sludge, etc. (hereafter referred to as “temporary placement, etc.”) or its transportation, the issues described below should be considered on the premise of respecting provisions in the Waste Management and Public Cleansing Act (hereafter referred to as “Waste Management Act”) in the controlled type landfill sites, while referring to the “Basic Approaches for Safety Assessment of Radioactive Waste Management Facilities,” (NSC Decision, 27 March 1989) “Reviewing Safety of Category 2 Radioactive Waste Disposal,” (NSC Decision, 9 August 2010) as well as the “Near-term policy to ensure the safety for treating and disposing contaminated wastes around the site of the Fukushima Daiichi Nuclear Power Plants” (NSC Decision, 3 June 2011).


1.    Application of the Ordinance on Prevention of Ionizing Radiation Hazards

When the dewatered sludge, etc. fall under the radioactive substances, by presenting the sum greater than “1” of ratios for radioactivity concentration of the radioactive isotopes in the left column and the values in the right column in Attached Table, as defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance, all of the applicable provisions in the Ionizing Radiation Ordinance shall be respected.


Attached Table (extract)

Type of radioactive isotope Concentration (Bq/kg)
134Cs 1 x 104
137Cs 1 x 104
  For instance, when radioactive substances contained in the dewatered sludge, etc., constitute 4,500Bq/kg of 134Cs and 5,000Bq/kg of 137Cs:

4500
-----------
10000
+
4500
-----------
10000
 = 0.95 < 1

the dewatered sludge, etc. do not fall under the radioactive substances defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance.

2.    Enhancing the containment features

When dewatered sludge, etc. are temporarily placed or transported, the dewatered sludge, etc. should be put in containers to prevent dispersion.


3.    Radiation shielding

(1)    Sufficient radiation shielding should be provided while considering the work conditions of workers and the environment around the temporary placement facilities (hereafter referred to as the “Facilities”).
The capability of the radiation shielding is estimated to reduce the dose equivalent rate, for example, to 1/10 by shielding with a 15 cm thick concrete wall, and to approximately 1/40 by shielding with a 30 cm cover soil1.
(2)    When the dewatered sludge, etc. are temporarily placed on soil, the soil should be matted with a water-shielding sheet in advance. In addition, any objects should be wrapped with a water proof material and covered with a water-shielding sheet to keep out the rainwater. Alternatively, any appropriate measures, such as shielding with a tent or a roof, should be implemented.

4.    Radiation monitoring

(1)    Any prefectural government with the facilities (hereafter referred to as “facility located prefecture”) are responsible for measuring the dose equivalent rate outside the radiation shield or the container of the dewatered sludge, etc. and recording the rate once a day or whenever the dewatered sludge, etc. are transported to the facilities.
(2)    Approximately once a week, the facility located prefectures are responsible for measuring and recording radioactivity concentration in the exhaust air of the incineration/melting facilities.
(3)    Approximately once a week, the facility located prefectures are responsible for measuring and recording radioactivity concentration in the seeping water, influent water, and processed water in the controlled type landfill sites where the dewatered sludge, etc. are temporarily placed.
(4)    Based on the measurement results in (1) and (2), the facility located prefectures should take necessary measures, such as enhancing the radiation shield, as required.
(5)    The facility located prefectures may commission the aforementioned measurement (1) and (2) to the facility operator. The concerning prefectures should take measures in (4) with the facility operator.
(6)    The frequency of the measurement in the above (1) to (3) shall be determined flexibly according to the results of previous measurement.

5.    Establishment of management system

(1)    Employers that generate the dewatered sludge, etc. should record the weight and the degree of radioactivity per unit weight of the dewatered sludge, etc., as well as the location of the temporary placement and keep the record.
(2)    When encountering the situation that corresponds to any of the following, the facility operators should report to the facility located prefecture (if the facility is located in one of the approved cities designated by the Ordinance, in accordance with the Waste Management Act, they should report to both the prefecture and the city) immediately of the conditions and response measures. The prefecture should seek advice from the national government in addition to taking appropriate actions in cooperation with the employers that generate the dewatered sludge and the facility operators without delay.
a.    Any portion of the dewatered sludge, etc. is missing.
b.    The management of the dewatered sludge, etc. is affected by a disaster such as fire.
c.    The radioactivity concentration, as measured in the aforementioned 4. (2) and (3) exceeds the concentration limit stipulated in Article 9 of the “Notice to Establish Dose Limit Pursuant to the Provision for Establishment and Operation of the Commercial Nuclear Power Reactor” (METI Notice, No. 187, 2001).
d.    Leaking of dewatered sludge, etc. is identified in the facility.

6.    Points of attention for temporary placement in the controlled type landfill site

(1)    The employers that generate dewatered sludge, etc. or the facility operator shall temporarily place the dewatered sludge, etc. after consultation with the prefectural government where the facility is located.
(2)    The dewatered sludge, etc. shall be temporarily placed separately in bulk so that they cannot be mixed with other wastes.
(3)    Dewatered sludge, etc., may be covered by soil to avoid dispersion. When cover soil is applied, the measurement in 4 (1) should be conducted at the location 1 meter above the soil.
(4)    Considering the situations associated with potential sinking of the ground, a water-shielding sheet should be laid out in advance and the object wrapped in the water proof material should be placed over the isolation layer approximately 30 centimeters from the soil (e.g., bentonite). Appropriate measures, such as covering the soil with a water-shielding sheet, a tent, or a roof, should be taken to keep out rainwater.

Appropriate measures should be taken to ensure safety during work involving temporary placement of the dewatered sludge, etc., and protect the environment around the area from negative effects of the facility by installing degassing pipes or providing air ventilation passages when covering with a tent, etc. to vent methane gas or hydrogen sulfide that may be generated. Furthermore, measures against sinking of the cover soil should be considered.
Finally, close attention should be paid to prevent rainwater from seeping into the existing waste layers.
(5)    In cases when a waste treatment employer is unable to continue its operation, the facility located prefecture or the employer that generates the dewatered sludge, etc., should take over the management responsibilities of the temporarily placed dewatered sludge, etc.

Source: External exposure dose conversion factor for evaluation of upper concentration limit for the land disposal (Japan Atomic Energy Agency, 2008)



Annex3

Policy on the management of disaster waste potentially contaminated with radioactive substances

19 June 2011

The policy on the management of the disaster wastes in Fukushima prefecture (excluding the evacuation area and the deliberate evacuation area) potentially contaminated with radioactive substances discharged by the nuclear power plant accident was formulated as follows.


Possible management methods and the routes through which effects of radioactive substances may be transmitted were assumed in the discussion. In the light of the results of the field surveys conducted by the Ministry of the Environment and the Nuclear and Industrial Safety Agency, the effects of cesium 134 and cesium 137, which are considered as the dominant nuclides, on the residents around the areas as well as on the workers were estimated. Their safety evaluation was conducted by comparing and examining these figures with the policy described in the “Near-term policy to ensure the safety for treating and disposing contaminated waste around the site of the Fukushima Daiichi Nuclear Power Plants” concluded by the Nuclear Safety Commission on June 3 (hereafter referred to as “NSC decision”). The policy on the management of the wastes was formulated based on the results of the evaluation.


(Note 1)   The evacuation areas, deliberate evacuation areas, the Aizu region, and ten municipalities that resumed the management on 27 May are excluded from the evaluation areas.
(Note 2)   The term “management” used in this document has the same meaning as the “management” used in the Waste Management Act. Thus, management constitutes “disposal” and “recycling.”

1. Principles
The major premise in the management of the disaster wastes potentially contaminated with radioactive substances is to secure the safety of the residents around the incineration facilities and final disposal sites as well as the involved workers, in accordance with the NSC decision. Keeping that in mind, considering the enormous volume of the disaster wastes, it is desirable to treat as much wastes as possible by incineration or recycling so that the volume of buried wastes will be minimized.
Because contamination levels vastly vary and some of the disaster wastes are highly contaminated, the “reference level” presented in the NSC decision may not be achieved immediately based on the current survey results, Furthermore, it may be difficult to ensure the long-term safety of people and the environment. Therefore, the wastes can be temporarily placed by the appropriate methods while the government continues to search for the safer disposal methods as soon as possible.
In addition, collecting the data on the ambient dose rate as well as monitoring of the groundwater around the management facility, exhaust air, and the discharged water from the management facility should be continued as backup measures. In the meantime until the concerned parties shall continue to coordinate with each other to find the better solution, the management of wastes should be conducted within Fukushima prefecture except for the wastes at around the clearance levels or at the lower contamination levels.


2. Incineration of combustible materials
Safe incineration of combustible materials, such as wood debris, will be possible if an incinerator equipped with an off-gas treatment system with the sufficient capability is used.
More specifically, safe incineration will be feasible in a facility equipped with off-gas treatment system that consists of a bag filter and off-gas absorption feature. In the facilities equipped with other types of off-gas treatment system, such as electric dust collector, incineration of disaster wastes shall be conducted on a trial basis to demonstrate its safety by measuring concentration of radioactive substances in the off-gas.


3. Management of main ash and fly ash generated by incineration
The main ash and fly ash generated by incineration of combustible materials such as wood debris could be safely disposed by burial by taking measures for protecting workers from radiation as well as by restricting the future use of the landfill site. Meanwhile, issues concerning the need for long-term administrative control of various burial sites, the future of environmental conservation, and the disposal of ash shall be addressed as follows:

(1) Main ash
The main ash with radioactive cesium concentration (a total of cesium 134 and cesium 137; the same shall apply hereafter) of 8,000 Bq/kg or less may be disposed by burial at the municipal final disposal sites (controlled type final landfill site) for the usual (municipal) wastes. This rough target (8,000 Bq/kg of radioactive cesium concentration) for main ash as well as for the water and sewage treatment by-products, discussed separately by the Nuclear Emergency Response Headquarters, is at the level in which the safety of workers can be ensured. In addition, it is desirable to store the ash in a facility capable of sufficiently shielding the radiation similar to facilities for handling water and sewage treatment by-products if the concentration level exceeds100,000Bq/kg.

The radioactive cesium concentration in the main ash is affected not only by the radioactive cesium concentration in the combustible materials prior to the incineration but also by the mixing ratio of other type of wastes than the disaster wastes.
The contaminated ash should be disposed separately from other municipal wastes and the location of the buried wastes should be recorded for a precaution when wastes are disposed by burial. There should be a layer of soil between the disposed ash and the discharging system for stored water. After the completion of the burial, the landfill sites should not be used for residential purposes in the future unless the safety is ensured to full satisfaction.
When the radioactive cesium concentration exceeds 8,000Bq/kg, rather than disposing by burial, the ash shall be stored temporarily until the behavior of radioactive cesium in buried main ash is understood and the safety of its disposal is confirmed by the government. The temporary placement, a step prior to the final disposal, shall be conducted in the following manner:
(i) Storage in drums at the location that can shield radiation
(ii) Storage at the municipal waste final disposal site (controlled type final landfill site)

   a.   Separate the location of disposal from other type of wastes and record the location.
   b.   Approximately 30 cm of isolation layer of soil, such as bentonite, should be created before the ash wrapped with water proof materials can be placed.
   c.   The wastes should be covered by a water-shielding sheet, a tent, or a roof to prevent rain infiltration.
   d.   The wastes should be covered with soil on the same day.

In the case of temporary placement, the wastes should be covered more frequently. Rather than covering the wastes only once at the end of the workday, more frequent periodical covering throughout the day or covering per section will be desirable in order to minimize the negative effect of the radioactive substances on workers. In addition, the operation hours per worker who handles contaminated main ash may need to be controlled (the safety assessment was based on the assumptions that cover soil is applied on the same day, a half of the 8 work hour per day, and, 250 days per year are spent near the contaminated main ash).
Furthermore, a sufficient distance should be kept between the location of the temporary placement area and the residential area (see the notes at the end).

(2) Fly ash
The radioactive cesium, concentrated in the fly ash and accumulated in the dust collector, tends to demonstrate higher level of radioactivity than the main ash. In addition, it is reported that the radioactive cesium contained in the fly ash can be easily dissolved into water.
For these reasons, as in the case of the main ash with radioactive cesium concentration of 8,000Bq/kg or higher, the fly ash should be placed temporarily until the safety of disposal is confirmed by the national government. If the concentration level is higher than 100,000Bq/kg, they should be stored in a facility capable of sufficiently shielding the radiation.
Similarly, the fly ash generated during the melting process of the ash incineration should also be placed temporarily. In principle, molten slag should also be placed temporarily, if it is confirmed that the cesium concentration level is below 8,000Bq/kg and disposal by burial is acceptable.


4. Direct landfill of incombustibles
Incombustible disaster wastes may be safely disposed by burial in their original form or after crushing. The burial methods and future use of the site shall be the same as those described for the main ash containing radioactivity of 8,000 Bq/kg or less.
The landfill workers are required to wear a mask as in any other cases of handling municipal wastes, but any special measures against the effect of radioactive materials would not be required.


5. Recycling
Even the disaster wastes that were potentially contaminated by radioactive substances due to the effect of the accident at the nuclear power plants could be recycled as long as the concentration of radioactive substances has been appropriately maintained below the criteria of the clearance level (10μSv/y) before the products made from recycled wastes are distributed to the market.
Even if the radioactivity concentration exceeds the clearance level at the time of utilization, it would be possible to continue its use while keeping it under control and taking some measures to maintain the radiation exposure dose lower than 10 μSv/y. One of the examples for “utilization while keeping it under control” constitutes recycling the wastes into base coarse materials used in construction for the land for public use. In this example, the recycled materials should be covered with soil in order to control the radiation exposure dose.
For metals that were potentially contaminated with radioactive substances, the contamination tends to remain on the surface of the metal. Thus, metal can be used after completely removing the contamination off the surface with solution such as water. In addition, the metals that had been placed inside a building before the temporary placement could be utilized. However, directly recycling the fractured concrete debris potentially contaminated with radioactive substances as the concrete wall material for a residential building should be avoided unless the safety of the utilization is verified.
Advisability for utilization of disaster wastes in other methods or utilization after decontamination needs to be discussed further.


6. Necessary surveys
In formulating the policy for the management of disaster wastes, a safety assessment was conducted assuming possible management methods and routes though which effects of radioactive substances will be brought based on the results of the field survey conducted by the national government. Still, a survey checking the validity of the assessment will be required for confirmation. Therefore, the level of contamination in the disaster wastes placed in a temporary placement area with relatively high ambient dose rate shall be assessed for confirmation. In addition, concentration of radioactive substances in the main ash, fly ash, off-gas, and discharged water that were generated by incineration, and ambient dose rate at the boundary of the final disposal site as well as the radioactivity concentration in the discharged water shall be measured.

The tsunami deposit (sludge) is expected to be at the same level as that of the soil around the area. However, the radioactivity concentration of the tsunami deposit shall be measured to confirm the current status of conditions in the area.


7. Ordinance on Prevention of Ionizing Radiation Hazards
In order to keep the radiation exposure dose of workers as low as reasonably achievable and to properly incinerate, to dispose by burial, and to recycle the disaster wastes, radioactivity concentration in the exhaust air from the incineration/melting facilities and the discharged water from controlled type final landfill sites should be periodically measured in a proper manner. Any parties concerned should take appropriate measures whenever necessary. In addition, the manager of incineration ash should record the amount of radioactivity concentration of the ash placed temporarily.
If there is a risk of the effective dose from external radiation at the site of the disaster to exceed the criteria [1.3mSv per three months (2.5μSv/h)], specified in Article 3, paragraph 1 of the Ordinance on Prevention of Ionizing Radiation Hazards (Ministry of Labor Order No. 41, 1972, hereafter referred to as “Ionizing Radiation Ordinance”) in waste incineration facilities, controlled type final landfill site, or if the incineration ash falls under the radioactive substances defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance (for radioactive cesium, when the total of concentration of cesium 134 and cesium 137 exceeds 10,000 Bq/kg), any applicable provision in the Ionizing Radiation Ordinance shall be respected to ensure the safety of workers.
In addition, the Ionizing Radiation Ordinance may also be applied to workplaces where fractured concrete in the disaster wastes, falling under the radioactive substances, defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance, are received as base coarse materials, etc.
When incineration ash, etc. with the radioactivity concentration level near the lower limit of the concentration of the radioactive substances specified in Article 2, paragraph 2 of the Ionizing Radiation Ordinance are handled, it is advisable for employers to monitor the exposure of workers in the light of “2. Treatment, transportation, and storage” in the NSC Decision.
When the radiation exposure dose of workers exceed 1 mSv/y, the relationship between radioactivity concentration in the incineration ash, etc. and the radiation exposure dose of workers shall be re-evaluated approximately 6 months after the accident based on the radioactivity concentration detected from the incineration ash, etc. at that time in order to reduce radiation exposure dose of workers to the lowest achievable levels.


8. Management method of the disaster wastes in the evacuation areas and the deliberate evacuation areas
The results of the survey conducted on the ambient dose rate around the location of temporary placement of the disaster wastes and on the radioactivity concentration in the disaster wastes in the Hamadori and the Nakadori areas demonstrate that the variability of the concentration level tends to be small in the area where the ambient dose rate is relatively low. Since the contamination sources of the disaster wastes are assumed to be generated via atmospheric fallout, the relationship between the radioactivity concentration of the wastes and the ambient dose rate identified in this survey may be generalized to other areas of Fukushima prefecture.
Thus, even in areas within the evacuation areas or deliberate evacuation areas where the ambient dose rate is estimated to be close to equal value to the value for the area outside of those areas, disaster wastes could be treated in the same way as the above 1 to 7. In order to devise an effective management plan that allows smooth processing of disaster wastes in those areas, detailed surveys of the ambient dose rate and a preliminary investigation on the form of the disaster wastes need to be conducted.
Meanwhile, disaster waste management methods in areas with high ambient dose rates have become the issue that needs further discussion. In these areas, the radioactivity concentration will be measured and examined for each type of the disaster waste to gain understanding in the current status of the situation and to determine feasible management methods.


9. Others
(1) Monitoring
In order to confirm the safety of the management, ambient dose rate around the management facilities, groundwater near the facilities as well as effluent from the facilities, need to be continuously monitored. The monitoring should be conducted by the national, prefectural, and municipal government offices according to the purpose of each office. However, it is desirable that all offices coordinate with each other to develop the standardized methods of monitoring if practicable. In order to serve this purpose, information about monitoring techniques should be promptly collected and shared among offices to stimulate discussion on the monitoring methods.

(2) Primary operator of the facility
The discussions in this report assumed that each municipal government processes the disaster wastes at its own incineration facilities and final disposal sites. Alternatively, a municipal government may commission the work to private employers who would process the wastes in the facilities under their private management. Considering that the management of the disaster wastes potentially contaminated with radioactive substances usually needs a long-term attention, the roles of the municipal government, prefectural government or cities, designated by the ordinance as a party that commissioned the project, or authorized superintendents of the management facilities should be clarified with further discussion if management of the disaster wastes will be commissioned to a private employer.
   (Note) Temporary placement of main ash with radioactivity concentration exceeding 8,000 Bq/kg and fly ash.

When considering the location for the temporary placement of the water and sewage treatment by-products, a sufficient distance should be ensured from the boundary of the residential area to the location as shown in Table below. The distance presented in the Table is calculated based on the assumption that a large amount of sludge will be stored every day. The distance is not immediately applicable for the temporary placement of the main ash and fly ash generated by incineration of disaster waste. However, the values introduced are considered to ensure sufficient safety around the location for placement of the main ash and fly ash. Thus, these values should be used as a reference until a more appropriate equation the isolation distance between the main ash and fly ash will be developed.

Table

1st Column 2nd Column
Target distance from the boundary A total radioactivity concentration of 134 and 137Cs
70m ≤ 100,000 Bq/kg or less
50m ≤ 70,000 Bq/kg or less
40m ≤ 60,000 Bq/kg or less
20m ≤ 40,000 Bq/kg or less
6m ≤ 20,000 Bq/kg or less
No limit ≤ 8,000 Bq/kg or less


Annex4

Occupational Safety and Health Department Notification No. 0623 No.2
23 June 2011

To:
Governor of Miyagi Prefecture
Governor of Fukushima Prefecture
Governor of Ibaraki Prefecture
Governor of Tochigi Prefecture
Governor of Gunma Prefecture
Governor of Saitama Prefecture
Governor of Chiba Prefecture
Governor of Tokyo Metropolitan
Governor of Kanagawa Prefecture
Governor of Niigata Prefecture

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

Interim policy on handling water and sewage treatment by-products and disaster wastes in which radioactive substances are detected

In relation to the accident of Fukushima Daiichi Nuclear Power Plant following the Great East Japan Earthquake, the Nuclear Emergency Response Headquarters released policy papers entitled “Interim policy on handling water and sewage treatment by-products in which radioactive substances are detected” and “Issues to be noted for storage, temporary placement and transportation of dewatered sludge and related materials,” while the Ministry of the Environment released a policy paper entitled “Policy on the management of disaster waste potentially contaminated with radioactive substances” (See Annex 1 -3).
Considering these policies, we concluded to apply the Ordinance on Prevention of Ionizing Radiation Hazards (hereafter referred to as “Ionizing Radiation Ordinance”) when assigning work concerning handling water and sewage treatment by-products and disaster wastes in a manner as described as follows. Please be aware of the content of this notification and disseminate the information to all the municipalities within your prefecture.
It should be noted that the same content of the notification was also sent to Directors of Prefectural Labour Bureau.
Thank you.


Notes


1.    Employers need to respect applicable provisions in the Ionizing Radiation Ordinance when dewatered sludge or its incinerated or melted form, disaster wastes or its incinerated form (hereafter referred to “dewatered sludge, etc.”), generated in the sewage treatment plant, water purification plant, incineration facility, and waste disposal facility (hereafter referred to as “the sewage treatment plants, etc.”) fall under the radioactive substances defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance and when the effective dose rate from the dewatered sludge, etc. could potentially exceed the value specified in Article 3, paragraph 1 of the Ionizing Radiation Ordinance[1.3 mSv per three months (2.5 μSv/h)].In addition, the Ionizing Radiation Ordinance may also be applied to workplaces where dewatered sludge, etc. that fall under the radioactive substances defined in Article 2, paragraph 2 of the Ionizing Radiation Ordinance are received as raw materials for cement or base coarse materials.
When handling dewatered sludge, etc. with a concentration level near the lower limit of the concentration of the radioactive substances specified in Article 2, paragraph 2 of the Ionizing Radiation Ordinance (about 80% of the lower limit), it is advisable for employers to monitor the radiation exposure dose of workers according to Article 8 and 9 of the Ionizing Radiation Ordinance.

2.    In order to control radiation exposures at such workplaces where dewatered sludge, etc. defined as radioactive substances are transported or received, information concerning hazards of the transported dewatered sludge, etc., has to be appropriately disseminated to the employer who transports or receives dewatered sludge, etc. Therefore, instructions should be provided to the sewage treatment plants within your jurisdiction that generate dewatered sludge, etc. defined as radioactive substances as per Annex-5 to ensure that they inform the employer who transports or receives such dewatered sludge, etc. concerning species, quantities, concentration, and so forth of radionuclide in the dewatered sludge, etc. to be transported in a written form.

(Annex 1 – 4 omitted)




Annex5

Sewage treatment plants and water purification plants that generated dewatered sludge, etc. falling under the provisions in Article 2, paragraph 2 of the Ionizing Radiation Ordinance

(Note)   The information presented below is the data promulgated on the date of the issuance of the notification. Therefore, new information may become available anytime. Watch out for the announcement from the sewage treatment plants and water purification plants located within your jurisdiction. It should be noted that the waste incineration facilities may generate incineration ash that falls under the radioactive substance after the start of incineration. It should also be noted that cement plants which receive dewatered sludge, etc. might be located outside the following list of prefectures:

Miyagi Prefecture

Operator Water Purification
plant name
Sampling date Cs-134 (Bq/kg) Cs-137 (Bq/kg) Remarks
Miyagi
Prefecture
Sennan Senen
Regional Water Supply,
Nanbusan Water
Purification Plant
30 May 9,584 11,373 Water purification
deposit
14,838 17,183

Fukushima Prefecture

Facility name Municipality
where
facilities are
located
Sampling
date
Results of radionuclide analyses (Bq/kg) Remarks
Cs-134 Cs-137 A total Cs I-131
Kennaka
Purification Center
Koriyama city 30 April 13,000 13,400 26,400   Dewatered sludge
165,000 169,000 334,000   Molten slag
Horikawa-cho
Sewage Treatment
Plant
Fukushima city 2 May 158,000 168,000 326,000 5,440 Dewatered sludge
4 May 216,000 230,000 446,000 6,160
Yokozuka Sewage
Treatment Plant
Koriyama city 2 May 7,860 8,280 16,140 96 Sludge sampled
on
2 May
3 May 3,720 3,940 7,660 69 Sludge sampled
on
25 April
Aizuwakamatsu City
Purification Plant
Aizuwakamatsu city 3 May 1,280 1,330 2,610 61 Sludge sampled
immediately after dewatering
8,500 9,230 17,730 298 Sludge outside
with chaffs that
has been
fermenting since
before the
nuclear accident
Chubu Purification
Center
Iwaki city 3 May 857 896 1,750 446 Sludge
35,700 36,800 72,500 339 Dust (*)
17,400 18,300 35,700 215 Burnt residue after the nuclear accident (*)
ND ND ND ND Burnt residue before the nuclear accident (*)
(*) Generated from sludge incineration at four final disposal plants in Iwaki city (Eastern region, Northern region, Southern region, and Central region)

Operator Purification plant name Sampling date A total of
Cs-134 and Cs-137
(Bq/kg)
Remarks
Fukushima Regional Water Supply Organization Surikami
Purification
Plant
12 May 239,183 Water purification deposit

Ibaraki Prefecture

Facility name Municipality
where
facilities are
located
Sampling
date
Results of radionuclide
analyses (Bq/kg)
Remarks
A total of
radioactive Cs
A total of
radioactive I
Nakakuzi
Purification
Center
Hitachinaka
city
3 May 493 290 Dewatered sludge
17,020 120 Incineration ash
11 May 13,365 ND Incineration ash
30 May 16,800 ND

Tochigi Prefecture

Facility name Municipality
where
facilities are
located
Sampling
date
Results of radionuclide analyses (Bq/kg) Remarks
Cs-134 Cs-137 A total Cs I-131
Sewage
Treatment and
Recycle Plant
Utsunomiya
city
2 May     32,000    
Kuroiso Water
Treatment Center
Nasushiobara
city
10 May 8,630 9,490 18,120 352 Dewatered sludge
17 May 6,840 7,540 14,380 154
23 May 7,320 8,130 15,450 87

Operator Purification plant
name
Sampling
date
Cs-134
(Bq/kg)
Cs-137
(Bq/kg)
Remarks
Utsunomiya city Matsudashinden
Water Purification
Plant
10 May 7,900 8,500 Water purification
deposit
18 May 5,060 5,770
Imaichicho Water
Purification Plant
23 May 17,000 19,000

Gunma Prefecture

Facility name Municipality
where
facilities are
located
Sampling
date
Results of radionuclide analyses (Bq/kg) Remarks
Cs-134 Cs-137 A total Cs I-131
Maebashi
Water
Purification
Center
Maebashi city 9 May 19,700 21,300 41,000 ND Incineration ash
7,990 9,100 17,090 ND Molten slag
20 May 20,500 22,300 42,800 ND Incineration ash
5,930 6,970 12,900 ND Molten slag
Akutsu Water
Purification
Center
Takasaki city 9 May 7,200 7,800 15,079* 100 Incineration ash
23 May 19,000 21,000 40,110* 205  
6 June     15,000 ND  

* 79Bq/kg of Cs-136 was contained on 9 May. 110Bq/kg of Cs-136 was contained on 23 May.


Saitama Prefecture

Facility name Municipality
where
facilities are
located
Sampling
date
Results of radionuclide analyses (Bq/kg) Remarks
Cs-134 Cs-137 A total Cs I-131
Motoarakawa
Water
Circulation
Center
Okegawa city 13 May 7,200 8,000 15,200 ND Incineration ash
(dry)
Arakawa Water
Circulation
Center
Toda city 13 May 6,800 7,400 14,200 ND Incineration ash
(dry)
5,100 5,500 10,600 ND Incineration ash
(wet)
27 May 6,100 6,800 12,900 ND Incineration ash
(dry)
4,600 5,400 10,000 ND Incineration ash
(wet)

Chiba Prefecture

Facility name Municipality
where
facilities are
located
Sampling
date
Results of radionuclide analyses (Bq/kg) Remarks
Cs-134 Cs-137 A total Cs I-131
Teganuma
Terminal
Sewerage
Treatment
Plant
Abiko city 20 May 9,400 11,100 20,500 ND Incineration ash

Tokyo Metropolitan

Facility name Municipality
where
facilities are
located
Sampling
date
Results of radionuclide analyses (Bq/kg) Remarks
Cs-134 Cs-137 A total Cs I-131
Tobu Sludge
Plant
Koto-ku 12 May 8,500 9,970 18,470 ND Incineration ash
18 May 11,000 12,000 23,000 ND
Kasai Water
Reclamation
Center
Edogawa-ku 12 May 24,100 29,100 53,200 ND
18 May 26,000 29,000 55,000 ND
Miyagi Water
Reclamation
Center
Adachi-ku 12 May 6,820 8,280 15,100 ND
18 May 7,300 7,900 15,200 ND
Shingashi
Water
Reclamation
Center
Itabashi-ku 12 May 9,430 11,700 21,130 ND
18 May 11,000 12,000 23,000 ND
Nanbu Sludge
Plant
Ota-ku 10 May 4,800 5,740 10,540 ND
18 May 7,400 8,200 15,600 ND
Kitatama
Number One
Water
Reclamation Center
Fuchu city 12 May 5,880 7,140 13,020 ND
18 May 5,800 6,500 12,300 ND
Kitatama
Number Two
Water
Reclamation Center
Kunitachi city 12 May 6,740 8,220 14,960 ND
18 May 7,800 8,900 16,700 ND
Kitano Sewage
Treatment
Plant
Hachioji city 13 May 7,100 7,910 15,010 ND
Nishiki-cho
Sewage
Treatment
Tachikawa city 17 May 4,820 5,728 10,548 ND
25 May 7,994 9,669 17,663 ND
1 June 6,030 7,282 13,312 ND

Operator Purification plant name Sampling date A total of
Cs-134 and Cs-137
(Bq/kg)
Remarks
Tokyo Metropolitan
Government
Kanamachi
Water
Purification
Plant
28 March 14,650 Water purification deposit

Kanagawa Prefecture

Facility name Municipality
where
facilities are
located
Sampling
date
Results of radionuclide analyses (Bq/kg) Remarks
Cs-134 Cs-137 A total Cs I-131
IrieSaki Comprehensive
Sludge Center
Kawasaki
city
13 May 6,400 6,800 13,200 ND Incineration ash
(rain)
16 May 4,900 5,200 10,100 ND Incineration ash
(sunny)
24 May 4,870 5,240 10,110 ND Incineration ash
(rain)
31 May 5,100 5,520 10,620 ND Incineration ash
(rain)
Shitamachi
Water Purification Center
Yokosuka
city
10 May 6,190 5,780 11,970 ND Incineration
ash
19 May 5,920 5,420 11,340 ND

Niigata Prefecture

Operator Purification plant name Sampling date A total of
Cs-134 and Cs-137
(Bq/kg)
Remarks
Niigata city Manganji Water
Purification
Plant
20 May 19,377 Water purification deposit
27 May 45,544
6 June 17,003

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