SUMMARY OF THE FIRST STEP OF ACTIVE TEST AT HEAD-END FACILITY OF ROKKASHO REPROCESSING PLANT

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1 SUMMARY OF THE FIRST STEP OF ACTIVE TEST AT HEAD-END FACILITY OF ROKKASHO REPROCESSING PLANT Tanaka, S. 1, Yamamoto, Y. 1, Kawabe, S. 1 and Kamada, Y. 1 1 Japan Nuclear Fuel Ltd., Rokkasho-mura, Aomori-ken, JAPAN Abstract: During the first step of Active Test (AT) at Rokkasho Reprocessing Plant (RRP), the performances of the Head-end Facility were checked, mainly for shearing and dissolution: Shearing force and shearing time were the values as expected and Concentration of U and Pu were the values as expected. And safety requirement for acidity was satisfied. Keywords : Reprocessing, RRP, Uranium, Plutonium, Krypton, Shearing, dissolution, PWR, BWR 1. Introduction Japan Nuclear Fuel Limited (JNFL) started active test of Rokkasho Reprocessing Plant (RRP) on March 31 st 26 and shearing was started on 1 st April 26. During the first step of active test (from April to June), about 3 tons of PWR fuels have been successfully reprocessed. Fuel characteristics were low burn-up (12, to 17, MWD/tUpr)/long cooling time (2y) and medium burn-up (3, to 33, MWD/tUpr)/medium cooling time (y to 18y). For the Head-end Facility, which includes shearing, dissolution, clarification and accountability (See Figure 1), the following items have been tested and evaluated. - Continuous shearing and dissolution performance - Mechanical parameters - Chemical performances After evaluation of these test results, the next step will be started. Tilting crane Fuel assembl Shearing machine Buffer vessel after accountability Basket Transfer Cart End piece HNO 3 Chopped fuels Clarifier Relay vessel Associate d vessel End pieces rinsers Dissolver Hulls Hulls rinser 1 st iodine desorber Measuring pot 2 nd iodine desorber Recycling vessel Buffer vessel before accountability Drum Main flow Flow except for main flow Hulls and end pieces Recovery vessel of fines Accountability vessel Figure 1 Flow sheet of the head-end process

2 2. Outline of Test Test operation at RRP consists of 3 steps, which are chemical test, uranium test and active test. And active test consists of 5 steps to ensure confirmation of safety function and performances at equipment and facilities. - Line A used at first, and then line B used - PWR fuels at first, and then BWR fuels - Low burn-up fuels at first, and then higher burn-up fuels Summary of test is shown in Table 1. Table 1 Summary of test Step No. and purpose Fuel specification Throughput * 1 st step (Line A) ** To confirm - Safety function of - Performances of HOLD Point 1 Evaluation of basic safety 2 nd step (Line A) To confirm at higher burn up and BWR - Safety function of - Performances of HOLD Point 2 Evaluation of basic safety 3 rd step (Line B) To confirm, on 2 nd line - Safety function of - Performance of 4 th step (Line A) To confirm - Safety function of the entire plant - Operational performances of the entire plant 5 th step (Line B) To confirm, for BWR - Safety function of the entire plant - Operational performances of the entire plant Burn up: about 12, to 17, MWd/tUpr Cooling time: about 2 years Burn up: about 3, to 33, MWd/tUpr Cooling time: about to 18 years Burn up: about 3, to 36, MWd/tUpr Cooling time: about 2 years (BWR) Burn up: about 18, to 21, MWd/tUpr Cooling time: about 2 years (BWR) Burn up: about 15, to 25, MWd/tUpr Cooling time: about 15 to 2 years Burn up: about 16, to 47, MWd/tUpr Cooling time: about 8 to 14 years Burn up: about 36, to 47, MWd/tUpr Cooling time: about 6 to 17 years (BWR) Burn up: about 2, to 4, MWd/tUpr Cooling time: about 8 to 2 years *):" t Upr " means counted mass in ton of metallic uranium before irradiation **): The 1 st step finished on June 26 th 26. About 3t Upr About 6t Upr About 7t Upr About 1t Upr About 16t Upr During the 1 st step, Shearing and dissolution tests have been performed and the following items have been checked. - Continuous shearing and dissolution performances - Mechanical parameters - Chemical performances The test results are as follows.

3 3. Test Results and Discussions 3.1 Daily throughput Daily throughput and total amount during the 1 st step campaign are shown in Figure 2. Daily throughput itu Apr 11-Apr Daily throughput tu Total amount tu 21-Apr 1-May 11-May 21-May 31-May -Jun 2-Jun 3-Jun Total amount itu Figure 2 Shearing results of the1st Step From 1 st April to 8 th April: 8 fuel bundles were sheared. From 3 rd May to 5 th May: fuel bundles were sheared. From 13 th May to 16 th May: 18 fuel bundles were sheared During this period, shearing parameters were adjusted to get good shearing performances. (e.g. decrease of blocking risk, decrease of shearing force) After the adjustment, 31 fuel bundles were sheared continuously from 7 th June to th June. The results were as follows. - Continuous shearing and dissolution were performed without major difficulties. - Mechanical parameters showed good performances. (Details are shown in the later paragraph.) - Shearing time for one fuel bundle satisfied the expected value and the maximum daily throughput was attained over than 4 tu/d. In conclusion, continuous shearing and dissolution were performed without major difficulties during the 1 st step. 3.2 Shearing machine parameters Shearing forces of both bottom end-piece (BEP) shearing and rods shearing are shown in Figure 3 and Figure 4, compared with uranium test results [1]. These figures show that: - Shearing forces of BEP were observed as lower than UT PWR results. Only one datum was higher than UT results, but sufficiently lower than the threshold value. - Shearing forces of rod were observed as slightly lower than UT PWR results except for 6 data. In fact, for 6 fuel elements the start position of pellets was different. However, values themself were sufficiently lower than threshold value. In conclusion, it was confirmed that present parameters give good shearing performances.

4 Shearing force/max. set num ber of fuels Figure 3 BEP shearing force UT (Line A, PWR) AT (Line A, PWR) Shearing force/max.set v UT (Line A, PWR) AT (Line A, PWR) num ber of fuels Figure 4 Rods shearing force 3.3 Dissolver parameters Wheel rotation torque is shown in Figure 5, compared with the uranium test results [1]. This figure shows that: - Wheel rotation torque was slightly higher than UT PWR results. - Two torque peaks were observed, but rotation at high level torque didn t continue. - Even these peak values were lower than the threshold value. In conclusion, it was confirmed that present parameters give good wheel rotation performance.

5 Rotation torque/warning value[%] UT (Line A, PWR) AT (Line A, PWR) Number of wheel rotation Figure 5 W heel rotation torque 3.4 Chemical performances During shearing of 31fuel bundles, acidity and U / Pu concentration were followed up. Activity of 85 Kr in Shearing/Dissolution off gas was monitored. The results were as follows. - Acidity of dissolution solution in dissolver satisfied the criticality safety requirement value. U and Pu concentrations in dissolution solution satisfied the expected values. - Trend curve of 85 Kr monitor corresponded to shearing operation (See Figure 6). It means that 85 Kr monitoring is pertinent means to confirm the arrival of chopped fuel in acid in dissolver. 85 Kr activity Shearing status 85 Kr behavior During shearing FE1 1/3 bucket FE1 2/3bucket FE1 3/3bucket Out of shearing Time Figure 6 Trend curve of 85 Kr m onitor during shearing

6 3.5 Equipment soundness after campaign After the 1 st step campaign, equipment listed below were inspected by remote operation. Significant damage or abnormal situation weren t observed. - Tilting crane - Shearing machine - Dissolver - End piece rinser - Hulls rinser 4. Conclusion The 1 st step of active test of the Head-end Facility at RRP was successfully achieved. During this step, about 3 tons of fuels were sheared and following items were confirmed. - Continuous shearing and dissolution were performed without major difficulties. - Mechanical parameters allowed good shearing performances. - Shearing time for one fuel bundle satisfied the expected value. - The maximum daily throughput was attained over than 4tU/d. - Acidity of dissolution solution satisfied the criticality safety requirement value. - U and Pu concentrations of dissolution solution satisfied the expected values. - After shearing of 3 tons fuels, no significant damage was observed for main equipments. 5. Reference [1] Shuji KAWABE, Hiroaki YAMAGUCHI, Masatsugu HASHIZUMI, Yoshiro YAMAMOTO, Takashi HAMADA, Uranium Test on the Head-end Facility at Rokkasho Reprocessing Plant, Proceeding of GLOBAL 25 Tsukuba, Japan, Oct 9-13, 25, Paper No. 398