Current status of J-MOX safeguards design and future prospects

Tsuyoshi Sampeia, Kazuhiko Hirutaa, Junji Shimizua, Ko Ikegamea

aMOX Fuel Fabrication Plant Construction Office,Japan Nuclear Fuel Limited, Okizuke, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori, Japan

Abstract. The construction of JNFL MOX Fuel Fabrication Plant (J-MOX) is proceeding toward active test using uranium and MOX in July 2017　and completion of construction in October 2017. Although the construction schedule is largely impacted by progress of licensing, according to domestic law, JNFL is making every effort to get necessary permission of business license and authorization of design and construction method as soon as possible. On the other hand, it is desirable that integrated safeguards approach is effective, efficient and consistent with J-MOX facility features. Discussion about the approach is going on among IAEA, Japan Safeguards Office (JSGO) and JNFL, and IAEA is planning to introduce the measures into the approach such as application of Near Real-Time Accountancy with frequent declaration from operator, Containment/Surveillance measures to storages, internal flow verification with 100%, random interim inspection (RII) and so on. RII scheme is intended to increase efficiency without compromising effectiveness and makes interruption of facility operation minimum. Also newly developed and improved safeguards equipment will be employed and it is possible to realize to increase credibility and efficiency of inspection by introduction of unattended/automatic safeguards equipment. Especially IAEA and JSGO share the development of non-destructive assay systems which meet the requirements from both parties. These systems will be jointly utilized at the flow verification, RII and PIV. JNFL will continue to provide enough design information in a timely manner toward early establishment of safeguards approach for J-MOX. Also JNFL will implement the coordination of installation and commissioning of safeguards equipment, and Design Information Verification activities for completion of construction in October 2017.

1. J-MOX construction schedule

J-MOX construction started after getting permission of business license in May 2010 and authorization of design and construction method in October 2010. Unfortunately Great East Japan Earthquake happened and JNFL had to stop the construction for about one year. The construction was resumed in April 2012 and since then it is continued. On the other hand, New Regulatory Requirements was designed in light of the lessons learned from the accident of Fukushima Dai-ichi Nuclear Power Station and was enforced in December 2013. According to domestic law JNFL submitted application document for license modification to comply with New Regulatory Requirements. At the moment, safety review by Nuclear Regulation Authority (NRA) is still on going. JNFL makes every effort so as to get permission of business license early and to keep current construction schedule. A commissioning and completion of construction are in July and October 2017 respectively in current J-MOX construction schedule revised in April 2014 as shown in Fig.1.

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Fig. 1. J-MOX construction schedule

2. Outline of J-MOX building

J-MOX is located at Rokkasho-mura Aomori prefecture in Japan which is north part of the main island. J-MOX is being constructed adjacent to Rokkasho Reprocessing Plant (RRP) and connected to MOX Product Storage Building (CB building) of RRP with underground tunnel. J-MOX consists of 3 buildings, which are Fuel Fabrication Building, Utilities Building and Administration Building. Rendering of J-MOX plant is shown in Fig.2.

Fig.2. Rendering of J-MOX plant2.1. Fuel Fabrication Building (PA building)

PA building to fabricate MOX fuel assemblies from feed MOX powder shipped from CB building is main building in J-MOX plant. It has 2 floors above ground and 3 basements with

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reinforced concrete structure. Its dimension is approximately 85m × 85m. Main production line is installed on B3F and B2F.

2.2. Utilities building (PB building)

PB building is located at west side of PA building and supplies electricity, gasses, water etc. to PA building. No nuclear material is handled. It has 2 floors above ground and its dimension is approximately 40m × 97m.

2.3. Administration building (PC building)

PC building is located at east side of PA building and is used for administration office, meeting room, metal parts inspection. No nuclear material is handled. It has 2 floors above ground and its dimension is approximately 70m × 70m.

2.4. Status of building construction

J-MOX construction has continued and the construction progress in total is about 9% as of September 2014. The progress of building construction alone has about 20% for PA, 90% for PB. As for PA building bar arrangement work for B3F is going on. Building construction of PB is near-completed. Status of building construction is shown in Fig.3.

Fig.3. Construction status of PA and PB building

3. Outline of J-MOX plant

3.1. Operating condition

Maximum design capacity is 130 t-HM/Y. J-MOX is to be operated within this capacity on condition that all amount of plutonium annually reprocessed in RRP are consumed through a series of production campaign in J-MOX. Basically operation mode under normal condition is two shifts per day and five operating days per week excluding the process of feed MOX receiving and pellet sintering.

3.2. Feed and Product material

Feed materials to J-MOX are MOX powder from RRP, UO2 powder from a re-conversion facility and UO2 fuel rods from LEU fuel fabrication facilities. The feed MOX powder is co-denitrated in RRP by using micro-wave heating technology, containing 50% plutonium and

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50% uranium. The feed UO2 powder is depleted uranium and used for dilution of MOX powder to adjust Pu content (Pu content = Pu/(Pu+U)) to required fuel specifications. The feed UO2 fuel rods are assembled with MOX fuel rods for BWR.

Product material is MOX fuel assembly for LWR (PWR and BWR). Each MOX fuel assembly consists of MOX fuel rods with different Pu contents (and U fuel rods in case of BWR MOX fuel assembly) and each MOX fuel rod consists of MOX pellets all of which are the same Pu content.

3.3. J-MOX Fabrication Process

Main processes from Powder Process to Packing & Shipping Process are shown in Fig.4.

Fig.4. Main process of J-MOX

The nuclear material handling area of J-MOX is composed of five (5) main processes and four (4) subsidiary processes as follows;

(a) Powder Process (Feed Powder Receiving and Powder Preparation)(b) Pellet Process (Pressing, Sintering, Grinding and Inspection)(c) Fuel rod Process (Pellet loading/welding and Inspection)(d) Fuel Assembling Process (Assembling and Inspection)(e) Packing and Shipment Process (Storage, Packing and Shipment)(f) Scrap Treatment (g) Test Line (h) Solid Waste Storage (i) Analytical Laboratory

3.3.1. Process description

(Feed Powder Receiving Process)

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A MOX canister that contains three MOX powder cans filled with feed MOX powder is received from CB Building of RRP through the underground trench connecting to J-MOX and temporally stored. UO2 powder is received from a re-conversion facility and stored.

(Powder Preparation Process) Necessary amounts of the feed MOX powder and the feed UO2 powder are dosed by weighing and blended through two dilution steps. MOX powder is diluted to 30% of Pu content in a primary blending and then further diluted to Pu contents (up to 16% of Pu content) in a secondary blending. All nuclear materials in this process are handled in a glove box.

(Pellet Process)The blended MOX powder is pelletized into the green pellets through the pressing machine and then sintered by sintering furnace. The sintered pellet is ground, inspected and stored as product pellet. All nuclear materials in this process are handled in a glove box.

(Fuel Rod Process)The product pellets are loaded into a cladding tube and an end-plug is welded. Up to this step, all nuclear materials are handled in glove boxes. The fuel rods go through a series of QC checks and stored.

(Fuel Assembling Process, Packing and Shipment Process)Fuel rods are bundled with UO2 fuel rods for BWR, grid-frames/spacer and other parts to form a MOX fuel assembly for BWR and PWR. The MOX fuel assembly is inspected and stored. The MOX fuel assembly is packed into a transportation container and stored until shipment to LWR.

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4. Cooperative Framework

JNFL started the consultation with the IAEA on the safeguards design for J-MOX from a very early design stage since JNFL applied MOX fuel fabrication business license in 2005. IAEA established Joint Technical Committee (JTC) under J-MOX WG in 2006 to coordinate safeguards equipment related issues. The organizational scheme shown in Fig.5 has been set up to make decisions efficiently in accordance with the content to be discussed. Especially technical meeting and JTC deal with SG approach-related issues and SG equipment respectively.

Technical meeting is the place to discuss about Operator’s declarations, verification requirements, verification methods and so on. Necessary safeguards equipment is clarified based on a discussion at technical meeting.

JTC concentrates upon effective coordination of safeguards equipment and approves all equipment owned by the inspectorates (JSGO and IAEA) and the operator at each hold-point from the design phase until the on-site test. JTC member consists of IAEA, JSGO/NMCC and JNFL and the tasks are mainly as follows. Approval of SG equipment Interface management between SG equipment and J-MOX equipment Approval of test plan for SG equipment at factory and installation site Coordination of test schedule in J-MOX construction schedule

Fig.5. Organizational Chart

5. Innovative Safeguards System

5.1. Basic Measures in Safeguards Approach

The measures currently employed in SG approach have been made clear through past discussion among IAEA/JSGO/NMCC/JNFL.

J-MOX SG approach is composed of robust combination measures and it allows the timely verification on the absence of nuclear material diversion as well as high confidence that the plant will be operated as declared. Such innovative Safeguards System is being developed by IAEA. Basic measures to be applied to J-MOX are as follows; Lifetime Design Information Verification (DIV) Sector approach with 100% unattended verification of flows between sectors under

Remote Monitoring

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Containment and Surveillance (C/S) Random Interim Inspection (RII) Near Real-Time Accountancy (NRTA) for Material Balance Evaluation Physical Inventory Verification (PIV) Common use of on-site laboratory (OSL) with RRP

5.2. Safeguards System

According to current SG approach the flow of nuclear material through the process is partitioned into the sectors where the same type of nuclear material is processed or stored and inspection activities are defined by each sector. Sectors for main process are as follow. MOX Canister Storage MOX Powder Preparation MOX Pellet Fabrication, Product Pellet Storage and Scrap Storage MOX Fuel Rod Fabrication ,Fuel Rod Storage and MOX Fuel Assembly Fabrication MOX Fuel Assembly Storage

The measures to be applied to each sector are shown in Fig.6.

Fig.6. Verification measures to be applied to each sector

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5.3. Safeguards Equipment for Non-destructive Assay

Non-destructive assay (NDA) systems to be used at each sector are being developed by IAEA, JSGO/NMCC and JNFL. NDA systems used for flow verification are designed to have unattended remote monitoring mode and 100% flow verification is achievable. All NDA systems can be operated through JTC approval at some hold points. NDA systems to be introduced to J-MOX are followings. IPCA (Improved Plutonium Canister Assay system) : all flows of feed MOX canisters

into and out of J-MOX and between sectors AMGB (Advanced Material accountancy Glove Box) : all flows of containers for MOX

powder and pellet between sectors, and into and out of C/S area GUAM (Glove box Unattended Assay and Monitoring system) : Plutonium inventory in

glove boxes FRSS (Fuel Rod Scanning Station) : Continuity of knowledge for fuel rod in process FRCA* (Fuel Rod Counting Array) : all flows of fuel rod into fuel rods storage under

C/S FRIS* (Fuel Rod Inspection System) : all flows of fuel rod into and out of fuel rods

storage under C/S FRCS* (Fuel Rod Counting System) : all flows of fuel rod from fuel rods storage under

C/S to assembling process AFAS (Advanced Fuel assembly Assay System) : all flows of fuel assembly between

sectors AVIS (Advanced Verification for Inventory Samples system) : inventory verification WPAS (Waste Package Assay System) : Inventory verification RSMC (Recyclable Scrap Multiplicity Counter) : flows of scrap material between main

process and scrap treatment processSome of above NDAs are used not only for flow verification but also inventory verification.

6. Future Prospects

Regarding approach for future construction schedule, as prolongation of safety review will largely impact on construction schedule, JNFL makes every effort to get early permission for modification of business license and in parallel to keep current construction schedule taking measures such as introduction of shiftwork, streamline of commissioning test etc.Regarding approach for future safeguards activity, JNFL will provide necessary information for appropriate implementation of DIV activities, timely coordination of interface between SG equipment and J-MOX facility. JNFL will make a precise coordination of installation, commissioning of SG equipment and DIV activities so as to be within current construction period.

These systems are under discussion.

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