5. SHIP PROPULSION NUCLEAR REACTORS, ATTENDED ENTERPRISES, WASTE STORAGES, SUNK NUCLEAR SHIPS

5.1. General

5.1.1. Objects of Navy and the Ministry of Economy of Russian Federation

The main sources of radiation hazards and environmental contamination of the Navy and the Ministry of Economy (the Department of Defence Industry):

1. submarines and surface ships with ship propulsion reactors (SPR);
2. technical vessels supporting the nuclear powered ships:
   technical tankers;
   technical depot ships for reloading reactors;
   "Amur" type technical tankers;
3. bases of the ships with SPR;
4. places of storage up and utilizing the ships with SPR put out of operation;
5. places of temporary storing the "fresh" and spent nuclear fuel (SNF):
   technical coastal bases and depot ships;
   bases of technical property;
   depot technical ships for reloading reactors of nuclear ships;
6. ship repairing and ship building factories of RF Ministry of Economy, where repairing the nuclear ships and reloading the reactor core take place;
7. radioisotope energy sources.

Radiation hazard also is concerned with consequences of tests of nuclear and radiological weapons and irregular situations with it. In addition, reactor operation and dismantling at the training centre of Paldisky (Estonia) and reactor operation at the Sevastopol Higher Naval Engineering school (at present it belongs to the Ukraine) are of concern.

As of the beginning of 1995 about 140 NS were withdrawn from operation. By 2000 156 NS will be removed from the Navy stock, including 95 and 61 NS from the Northern and the Pacific navies, respectively.

In the Russian Federation the concept for dismantling the nuclear submarines (NS) has been adopted and is being implemented. However, the potentialities of the industry for accomplishing these works are far from being sufficient. The mass withdrawal of NS of the second generation from operation in accordance with the international large-scale commitments of RF under disarmament agreements has been superimposed on the planned withdrawal of . NS of the first generation from operation because of their wear and tear. Meanwhile the accumulation of the NS is under way. They are stored for a long time. The first delay is waiting for the SNF removal, then - cutting out, sealing and prolonged storing the reactor compartment to allow decreasing the ionizing radiations levels by natural radionuclide decay and reducing the radiation hazard of the subsequent works on reactor unit dismantling. The long-term storage of reactor compartments has not been put into operation yet.

The great number of decommissioned NS with unloaded reactors and reactors containing the SNF as well as the increasing number of reactor compartments cut out gives rise to the problem of ensuring the radiation safety under conditions quite different from those of normal NS operation.

At present up to 2/3 of decommissioned NS are being stored with SNF aboard. The storied ships are dispersed geographically. The NS are being gradually sent to ship-repairing yards. The enhanced dispersion of NS is noted in Severodvinsk. In March of 1995 16 NS, to be utilized and repaired with 32 nuclear reactors still containing nuclear fuel were within the precincts of this town with 240000 population.

Since July 4, 1992 the experimental utilization of 13 NS has been underway with the following distribution of submarines by four ship-repairing yards:

PO "Sevmashpredpriyatie" (Severodvinsk) - 3,

GMP "Zvezdochka" (Severodvinsk) - 4,

DVZ "Zvezda" (B.Kamen,Primorsk Land) - 4,

SRZ "Nerpa" (Snezhnogorsk, Murmansk region) - 2.

The works were completed in 1995-1996.

A strong tendency to the accumulation of SNF in Severodvinsk remains as the actual Navy potentiality of SNF discharge in the Northern region is not more than three NS per year. The liquid radioactive wastes (LRW) reprocessing has not been balanced yet: their accumulation exceeds about 2,0-2,5 thous. m³ per year, whereas the capacity of the reprocessing installations is somewhat more than 1 thous. m³ per year.

In the Far East the NS utilization is effected at DVZ "Zvezda" with the capacity of 2-3 NS per year instead of the assumed capacity of 5-6 NS per year.

Earlier, 20 cores were annually delivered to the reprocessing plants. Currently, in view of the change-over to such new transport containers as TUK-18, the shipping capabilities are reduced because of the insufficient quantity of new containers and other reasons.

5.1.2. Objects of civil marine fleet

At present eight civil nuclear ships are in operation in Russia. These are seven nuclear ice-breakers and lighter "Sevmorput" belonging to the Murmansk marine steamship line (MMS). The first nuclear ice-breaker "Lenin" was put out of service in 1990. The spent nuclear fuel therewith was unloaded from the reactors. The other data about activity and radionuclide content for SPR equipment as well as circuit surfaces of ship reactors are unavailable. Now ice-breaker "Lenin" is in an "Atomflot" base which is engaged in repairing the reactor facilities of MMS, storing the SNF, collecting, storing and reprocessing the radioactive wastes provided during the operation of ships.

Here too in 1988 the decommissioned floating technological base "Lepse", serving as a storage of defective spent nuclear fuel, is laid up.

5.2. Characteristic of radioactive materials (RM) and radioactive wastes (RW) accumulated

5.2.1. Quantity, composition, storing and reprocessing conditions of RM and RW of RF Navy

The summarized data on radioactive wastes stored at the Naval objects and RF Minoboronprom's factories are presented in Table 5.1. More recent data haven’t been published.

Solid radioactive wastes are presented by constructional materials of the nuclear reactors, fuel elements of the damaged submarines, spent ion exchange resins used in the water purification filters of primary circuit, radioactive sediments formed during accidents of SPRs.

In the NS reactors without SNF the radionuclides of two groups are potentially hazardous. These are radionuclides of the activation origin and radioactive fission products. In the first radionuclide group the hazard is determined by accidental spread of ⁵⁵Fe (half-life is 2.7 yrs), ⁶⁰Co (5.27 yrs), ⁶³Ni (96 yrs) as well as sometimes ¹⁵²Eu-(13.3 yrs), ¹⁵⁴Eu-154 (8.8 yrs) and ¹⁵⁵Eu (4.96 yrs). In the second group the main dose responsible radionuclides are as follows: ⁹⁰Sr (29 yrs), ¹³⁴Cs (2.06 yrs) and ¹³⁷Ce (30 yrs). Europium radionuclides are formed in the control rods of some nuclear reactors, as it is not necessery. The fission products may be present in the reactor coolant circuit in the form of sediments on the inner surfaces as a result of the reactor operation with failed (nonsealing) fuel rods.

The decommissioned NS differ by the modes of previous operation. The most conservative supposition (operation at power equal to 20% of nominal for 200 thous. hrs) is appropriate to the accumulation of the following radionuclides in metal structures inside the reactor: ⁵⁵Fe about 1.5x10⁵ Bq (4x10^-4 Ci), ⁶⁰Co about 1.4x10⁵ Bq (3.8x10^-4 Ci) and ⁶³Ni no more than 0.3x10⁵ Bq (0.9x10^-4 Ci). These figures refer to the holdup within two years since the reactor shutdown. In the conservative supposition one would expect an availability of long-lived ⁹⁰Sr and ¹³⁷Cs up to 1.9x10¹¹ Bq (5 Ci) in the sediments inside the primary circuit.

The NS reactors unloading is accompanied by formation of liquid and solid radioactive wastes (LRW and SRW, respectively), of which LRW are the most mobile and, accordingly, the most potentially hazardous. Their total amount accompanying the recharging of one reactor is about 50 m³ at a radionuclide concentration not exceeding, as a rule, 3.7x10⁵ Bq/l (10^-5 Ci/l). Such LRW are referred to the low specific activity waste category.

Liquid radioactive wastes produced by Naval installations, have specific activity from 3.7x10³ to 3.7x10⁸ Bq/l, of which about 30 % is due to slightly salty drainage waters of 1,2,3 circuits and 70% - on highly salty (decontaminated waters due to operating and repairing SPRs). Depending on the project and the submarine generation in the reload of one reactor of a nuclear submarine, from 100 m³ up to 150 m³ of LRW are produced in the average, of which approximately 50% have specific activity more than 3.7x10⁵ Bqi/l, including about 10% which have activity of higher than 3.7x10⁶ Bq/l. The volume of decontaminated waters is about 60 m³, 8-10 m³ of them with a specific activity of more than 3.7x10⁵ Bq/l.

Liquid radioactive wastes produced in the process of operating, repairing and utilizing the Navy atomic ships are stored in the coastal and floating tanks, on the floating technical bases of recharging and the technical tankers. The existing Naval SNF and RW storages were built in the 60s.

Table 5.1

The characteristics of radioactive wastes stored at the Navy objects and the RF Ministry of Economy enterprises as of 01.01.94¹

¹- there are no published data for the lattest period of time (1995-1997)

The Navy possesses the following objects for storing and reprocessing the liquid radioactive wastes:

• At the Northern Fleet:
• coastal storages of total capacity 5.300 m³;
• floating storages of total capacity 3.700 m³;
• the station for reprocessing the radioactive water of the technical transport "Amur" (before 10.01.95 under repair).
• At the Pacific Fleet:
• coastal storages of total capacity of 3.500 m³;
• floating storages of total capacity of 3.000 m³;
• the radioactive water reprocessing station of the technical transport "Pinega";
• two experimental mobile plants "Sharya M" (having been in experimental operation since August, 1994).

At present, up to 30% of coastal and floating tanks are not in service because of expired operational guaranty or the lack of leak-tightness. The remaining part of coastal and floating reservoirs is practically completely filled (100%). Their construction is inconsistent with the international recommendations, as well as national and departmental requirements of ensuring the radiation safety at storing the LRW. Temporary storages of radioactive wastes are not built at the Fleets for the lack of financing.

The Northern and Pacific navies have one ship (the above-mentioned "Amur" and "Pinega"), each for RW transportation and reprocessing. Each ship carries about 800 tons of liquid radioactive wastes and has a station of radioactive waters reprocessing designed to purify up to 5 m³ of water per hour with decontamination factor equal to 100. These facilities are not operated owing to impossibility of the subsequent hardening of radioactive sludge, a product of liquid radioactive waste reprocessing. Specifications of modernizing the ships' LRWs reprocessing stations have been developed. Moreover, there exist three ships (two - at the Northern and one at the Pacific navies) for recharging the NS reactors with a system of purifying the primary coolant with a capacity of 10 m³ per hour. These mentioned systems are not used for their technological drawbacks.

The LRW reprocessing at the Northern Fleet is temporarily carried out at the repair-technological enterprise "ATOMFLOT" (in 1994 and 1995 it received 1.000 m³ of LRWs to reprocess), the LRW reprocessing at the Pacific Fleet is performed by two experimental plants "Sharya M" with a capacity of 1-1,5 m³ per day.

All spent nuclear fuel from the bases of the Northern and Pacific Fleets is scheduled to be removed for reprocessing at Minatom’s facilities. SNF, used in the reactors of the training center situated in the town of Paldisky, was removed completely. Works on conservation of other reactors’ RW at the site, including vessels of ship propulsion reactors, were completed.

At present, the problems of handling SNF not subject to reprocessing, as well as fuel of the damaged nuclear submarines' reactors have not been solved.

The accidental situation with the ingress of sea water into the primary circuit of SPR is accompanied by the destruction of sediments on the inner surfaces accumulated in the process of reactor operation and subsequent escape of radionuclides to the water. At the release of radioactive materials into the environment the content of these sediments makes a contribution comparable with that of radionuclides from metal structures, although the absolute quantities of nuclides accumulated are quite different. Higher by some orders the ⁶⁰Co content in the vessel structures proves to be comparable to the release of small quantities of ⁹⁰Sr and ¹³⁷Cs from the sediments in radiation hazard. In this case the main factor proves to be the very low rate of metal corrosion in sea water. This can greatly enhance the advantageous radioactive decay of ⁶⁰Co in comparison with its release to water due to corrosion. The accidental release of radionuclides to the sea water due to corrosion is estimated as ⁵⁵Fe and ⁶⁰Co release, about 6.29x10¹⁰ Bq/yr and ⁶³Ni - 1.48x10¹⁰ Bq/yr. Altogether 4.81x10¹¹ Bq of ⁶⁰Co, 4.44x10¹¹ Bq of ⁶³Ni and approximately 1.85x10¹¹ Bq of ⁹⁰Sr and ¹³⁷Ce would enter the water during all the post-accident period. Radiation doses produced in this case are not hazardous from the standpoint of radiation impact on environmental objects.

A more serious situation is due to the accidental sinking of NS with the reactors containing SNF. Then, the potential hazard of the release of the radionuclides accumulated in fuel or from the core fuel rods to the sea water arises. For a 2 year holding since the reactor shutdown the total radionuclide radioactivity in SNF is characterized by a level of about 7.4x10¹⁵ Bq (2x10⁵ Ci), where the following radionuclides make the main contribution: ¹⁴⁴Ce (2.2x10¹⁶ Bq), ¹⁴⁷Pm (1.2x10¹⁵ Bq), ¹³⁴Cs, ¹³⁷Cs and ⁹⁰Sr (each by 0.4x10¹⁵ Bq), as well as ¹⁰⁶Ru (0.2x10¹⁵ Bq). Both ¹⁴⁴Ce and ¹⁰⁶Ru have relatively short half-lives: 0.78 yr and a year, respectively. The half-lives of ¹³⁴Cs and ¹⁴⁷Pm are somewhat longer: 2.06 yr and 2.64 yr, respectively. ⁹⁰Sr and ¹³⁷Cs have the highest half-lives - about 30 yr. Their radioactivity in the SNF is by 2000 times higher than was predicted for possible surface sediments in the ship propulsion reactor with unloaded fuel. Data cited in this chapter indicate much greater radiation hazard of the NS sinking with SNF remaining in the reactor.

It follows from the experimental data obtained in Murmansk at the "Atomflot base" that the rate of the strontium-90 release from the fuel rods to the sea water will not exceed 1% a year from the activity accumulated in the SNF. For burnup adopted above the ⁹⁰Sr release (3.7x10¹² Bq/yr) conforms to this, that is a factor of 20 higher than the previous estimate for the reactor sinking without SNF.

On the whole, it is reasonable to suppose that the accident associated with the NS sinking without SNF aboard practically doesn’t cause any serious radiation consequences. In parallel with this an additional quantitative analysis of radioecological consequences of the accident with the sinking of the NS with SNF in the reactor is needed. The conservative approach commonly used for such calculations in full measure takes no account of the complexity of migration paths of radionuclides from their source (the fuel rods with SNF) to the environment - the sea around the NS sunk. There isn’t any reason to think that the sea water ingress to the reactor gives rise to rapid mass cladding failure with favourable conditions for large-scale interaction of the sea water with the fuel rod kernels. It has been experimentally determined that corrosive destruction of the fuel rods doesn’t create an extensive zone of direct contact of the kernels with water. In fact, radionuclides penetrating into the primary circuit of the reactor are brought into stagnant water. Its exchange with the environment cannot be active; it takes place with the retardation of the nuclides first in the reactor volume, then in the reactor unit equipment compartment and, finally, in the RW volume outside this compartment. Precipitation of the nuclides occurs in all these volumes due to their transport retardation. 5-year full-scale observations of the ¹³⁷Cs release from the reactor of the sunk NS "Komsomolets" using high-sensitive equipment points to the low rate of this radionuclide transport out of the NS hull - no more than 3.7x10¹⁰-3.7x10¹¹ Bq/yr.

Along with the accidents associated with the NS sinking and penetration of sea water into the ship propulsion reactor the reactivity accidents resulting in the initiating the fission chain reaction should also be mentioned. However, when the NS is laid up, any reactivity changes in the reactors with fuel are blocked by reliable mechanical fixing the positions of all operation units, subject to reactivity. Ship propulsion reactors of NS withdrawn from operation are under deep subcritical conditions.

In the RRC "Kurchatov Institute" and Navy's archives the relatively detailed information is available only for one of the accidents on nuclear submarines, accompanied by considerable release of radionuclides to the environment. This is the reactivity accident which took place on August 10, 1985 at one of the Pacific Fleet's submarines in the Chazhma Bay (set.Shkotovo-22, Primorsky land).

At the completion of works on reloading the reactors, a spontaneous chain reaction was initiated in the left board reactor because of violation of the nuclear safety requirements and the technology of reactor's cover explosion. In response to the thermal explosion the bow and the after body apparatus compartments were destroyed, a part of "fresh fuel" was thrown out of the reactor's vessel, the reloading facility was demolished (its roof was thrown out by explosion by 70-80 m and fell into the water at 30 m from the coast ), the submarine received damages of the strong hull in the after-body part of the reactor compartment. Immediately after the explosion a fire in the reactor compartment arose, which was localized in 4 h.

It is found that the formed combustion products together with both fission and activation products and the particles of unreacted fuel composition (in the form of coarse-dispersed particles and slag) fell out around the damaged submarine in a zone of radius 50-100 m. In 7,5 h after the accident the exposure dose rate in the accident area reached 250-500 mrem/h, surface density of radioactive contaminations - (0.5-4)x10⁶ dist. / ( min/ cm²).

The gaseous radioactive cloud originated by the accident crossed the Peninsula Danube in north-west direction and went to the coast of Ussuriysky Gulf. The results of full-scale studies of sea water and bottom sediments allowed a conclusion to be made that at further moving of the radioactive cloud over Ussuriysky Gulf area (width of 28-30 km) the density of fallout decreased to the background level and did not influence the radiation situation in Vladivostok and its beach zone. On evidence, 1989-1991 the exposure dose rate near the coastal line of the Shamora Bay was equal to 6-8 mrem/h.

The weather conditions at the moment of the accident were favorable for the fact that settlement Shkotovo-22 located at 1.5 km from the place of submarine mooring did not suffer from the radioactive fallout. The main part of radioactivity fell primarily to the territory of factory adjacent to the Chazhma Bay water area and the uninhabited part of the Peninsula Danube.

According to estimates, the release of the radioactive short-lived radioactive noble gases comprised approximately 7.4x10¹⁰ MBq, and of the other volatile fission (basically of the iodine isotopes) and activation ( predominantly ⁶⁰Co and ⁵⁴Mn) products was about 1.85x10¹¹ MBq.

The radiation monitoring of the environment revealed that the highest density of fallout was concentrated in a forest tract, on a narrow area 3.5 km in lenght and 200-650 m wide of the total area of 2 km². In 5-7 months the radiation situation was normalized over the whole territory of the factory. In 2 months after the accident the contents of radionuclides in the sea water decreased to the initial background levels.

The radioactive trace on the Danube Peninsula was due to ⁶⁰Co activity 95-99 % and to a considerably smaller degree due to ¹³⁷Cs activity. This trace has a spotty character. In one of the trace sections a temporary near-surface storage for the contaminated factory equipment was built. The storage and the main part of the trace on the uninhabited territory were fenced with barbed wire. A long-standing analysis of the measurement dynamics of environmental radioactive contamination has shown that radionuclides are primarily strongly sorbed on to the soil. Their total removal with the surface waters to the Chazhma Bay is assessed as 1.85x10⁸ - 7.4x10¹⁰ Bq/year.

As a result of the accident the center of the long-lived radioactive contamination of the Chazhma Bay bottom sediments was formed primarily by ⁶⁰Co ( 96-99 % ) and partially by ¹³⁷Cs. The area of radioactive contamination is about 0.1 km². In the middle of the center the exposure dose rate reaches 20-40 mR/h (maximum 117 mR/h as of 1992 ).

The maximum specific activity of ⁶⁰Co in the bottom sediments in the place of the accident amounts to 7.77x10⁴ Bq/kg, in the sea hydrobionts - up to 6.66x10⁵ Bq/kg. The movement of the contaminated bottom sediments from the Chazhma Bay to the western passage of the Arrows Gulf is observed. Contamination of the eastern part of the Ussuriysky Gulf water area in radius of 3-5 km from the place of the coastal radioactive trace exit causes excess of the exposure dose rate over the background within the limits of 1-8 mR/h.

The concentration of radionuclides in the Chazhma Bay sea water, the western passage of the Arrows Gulf and the eastern part of the Ussuriysky Gulf is at the level of background values, characteristic of other regions of the Pacific coast.

The observable tendency to the transport of the radioactive contamination in the natural layer and its dispersion over the Chazhma Bay will not lead to serious ecological consequences, as the general activity of ⁶⁰Co in the bottom sediments is comparitively low ( about 1.85x10¹¹ Bq).

The radiation safety service of the factory carries out constant monitoring of the radioecological situation in the accident area and on the radioactive trace. The chemical and medical services of the Pacific navy, seaside fleets, regional sanitary and epidemiological station and hydrometeorological organizations carry out periodic measurements of radionuclide contents in environmental objects.

The results of the full-scale observations and numerous radioecological inspections indicate that the accident on the submarine in the Chazhma Bay in 1985 had not a measurable radiation effect on Vladivostok, its beach zone and settlement Shkotovo-22. The residual long-lived radioactive pollution of the environment and bottom sediments in the Chazhma Bay region has been reliably localized and would not lead to serious radioecological consequences.

At present the Navy has 4 damaged submarines, of which three are in the Far East, in the Pavlovski Bay (project 675, serial No. 175 and 541 and project 671, serial No. 610) and one - in the North (project 675, serial No. 533). The cores of submarines No. 541 and 533 are planned to be discharged.

The technical measures of ensuring the nuclear and radiation safety are provided at the points of NS storing. However, the risk of accidental release of radioactive materials into the environment has a very small, but the finite value. In this connection the information about the reactor compartments as potential sources of radionuclides is very important.

With consideration for a number of works performed at the first stages of NS decommissioning procedure it is reasonable to believe that the NS with discharged spent nuclear fuel should be stored not earlier than two years after the shutdown of the nuclear reactors. Thus the potential hazard of an accident at the NS transferred to the storage conditions with a reduced operational personnel is determined by radionuclides with long half-lives (See 5.2.1).

5.2.3. Quantity, composition, storing and reprocessing conditions of RW of civil marine fleet

The radioactivity of the wastes produced in operation of the civil ships of the icebreaker’s fleet of Russia with SPR and the temporarily stored on the special crafts and in the coastal RTE "Atomflot" facilities is specified by both the neutron activation and fission products.

Integrated data about radioactive wastes stored at the civil nuclear fleet objects are listed in Table 5.2 as of the end of 1995. More recent data haven’t been published in open press. Such information is presented in annual reports of Radiation Safety Service of MMS, which are regulary delivered to the Department of Marine Fleet of the Transport Ministry of RF.

Table 5.2

Characteristics of radioactive wastes stored at the RTE "Atomflot"

As pointed out above, the most part of these RW is grouped on the floating base "Lepse" containing the damaged SNF. As of 01.01.95 the total activity in this storage amounted to about 2.78x10¹⁶ Bq, the fraction of ¹³⁷Cs and ⁹⁰Sr being 70% and that of actinides (²³⁸Pu, ²³⁹Pu, ²⁴¹Am and ²⁴⁴Cm) - no more than 3% of the total activity. Solving the problem of "Lepse" base handling was incorporated into "Federal target program on RW and spent nuclear materials handling, their utilization and disposal for a period from 1993 to 1995 and up to the 2005". Moreover, the problem outlined is reflected in the plans of activities of the Euroarctic (Barents) region.

Because of the frequency of ship movements in the water area of the Kola Bay the possibility of collision of ships with the "Lepse" base cannot be ruled out as well as the sinking of the latter because of progressing aging of the hull. This may involve a very hazardous contamination of the environment.

Development of solutions for the complex handling the "Lepse" base is also of interest from the viewpoint of handling Navy auxiliary ships and compartments with SPR with the unremovable SNF

In Murmansk on the RTE "Atomflot" a sorption installation of a capacity of about 2.5 m³/h designed for decontamination of LRW from nuclear icebreaker’s fleet is in operation. This is the only installation in the country capable of decontamination of LRW of all types formed in operation of the transport nuclear power plants to levels of the radionuclide contents suiting the requirements of "Norms of radiation safety( NRS-76 / 87)".

To the present more than 8000 m³ of LRW of different types has been decontaminated on the special water treatment installation of the RTE "Atomflot". The capacity of this installation permits an essential part of LRW of low specific activity formed in operating and repairing the Northern navy's ships and the nuclear ships of the MMS to be reprocessed. For the complete solving of the problem on decontamination of all kinds and volumes of LWR produced in the Northern Fleet, it is necessary to equip the existing water treatment installation with additional tools.

5.2.4. Marine RW disposal, sunk nuclear ships

SRW of low and medium specific activity, dumped in the sea are either enclosed in containers or if nonsealed are composed of polyethylene films, clothes, footwear, tools, as well as faulty equipment accessories - valves, pipes, circulation pumps, steam generators, ion exchange filter casings, contaminated in the process of repairing. Most of radionuclides is concentrated in the equipment and its corrosion films. These are primarily short-half-life activation products, such as ⁶⁰Co. The films also contain a quantity of fission products. In the whole this mixed composition of radionuclides is typical for SRW. It is impossible to separate them and give an adequate quantitative evaluation of each group. It has been admitted to be inexpedient to carry out the further refinement of activity and radionuclide content in connection with the small contribution of SRW to the total quantity of sunk wastes, as well as with the local character of water masses and bottom sediments. In the immediate vicinity of sunk SRW this was specifically demonstrated by the results of International Russian-Norvegian expeditions to the Kara Sea in 1992-1995.

The analysis and generalization of the information characterizing RW sunk in the Arctic regions or removed into the near surface layer of water of the Barents and the Kara Seas, have shown, that the long-lived radionuclides contained in SNF and ship propulsion reactors sunk in the bays of the eastern coast and in the vicinity of the Novaya Zemlya archipelago may be a maximum potential radiation hazard.

For these reactors sunk with SNF and without it, the considerable body of the information was obtained by the beginning of work under the "Radleg" project. In addition to the materials of "White Book - 93" in the framework of IASAP International Program the experts from RRC "Kurchatov Institute" and Institute of Energy Physics (Obninsk) of the Minatom estimated the radionuclide composition and activity in all 10 ship propulsion reactors sunk, as well as in 7 kits of SNF sunk. It has been shown that the main part of activity is determined by the container with SNF of the nuclear ship "Lenin": it’s comparable to the activity of all other sunk reactors including the reactors of damaged NS with SNF (Table 5.3).

It has been also established that the essential mistakes were made at publishing the first official document: gross activity of RW sunk overrated a 2.5 times in comparison with the true one. This activity has never exceeded 2.59x10¹⁶ Bq (700 kCi) with regard to the decay of relatively short-half-life radionuclides. At present, the gross activity of radionuclides in the sunk SPR and SNF doesn’t exceed 4.81x10¹⁵ Bq (130 kCi). It’s many times less than the gross activity of long-lived radionuclides sunk by the states of West Europe in Northen Atlantic in the process of implementing the London convention of 1972.

After publishing the data about sinking the NS with SNF and other RW in the northern seas in 1993 the open inspection of gulfs of the Novaya Zemlya archipelago began. The first expedition was organized by RF Navy on the "V.Kavraysky" ship in August - September 1993. The specialists of RPE "The Khlopin Radium Institute", RRC "Kurchatov Institute", Navy and Central testing site of the Ministry of Defence took part in this expedition. Gulfs of Ambrosimov, Stepovoi, Tsivolki, Oga, Sedov, Techenii and Blagopoluchie, and also Novaya Zemlya's depression were inspected. In each gulf 2-3 stations were set up with the dose rate measurements on the water surface, at different depths and in the near bottom, as well as with determining the radionuclide activity by immersed gamma-spectrometer and sampling the water and sediment deposits for radiochemical analyses. The investigations performed didn’t reveal any deviation from background radiation situation due to natural radionuclides and global fallouts.

In 1993-1995 the International Russian-Norwegian marine expeditions inspected all the above-mentioned Novaya Zemya’s gulfs, as well as Novaya Zemlya’s depression. A correlation between the data obtained and the results of Navy expedition shows reasonable agreement. The general conclusion is that the radiation doses are low here and the radionuclides concentrations outside of the gulfs are no different from concentrations in open regions of the Kara Sea. Higher concentrations of ¹³⁷Cs and ¹⁵²Eu revealed in some points of Stepovoy and Ambrosimov gulfs have been accepted not attendant upon the radionuclide release from both sunk NS and container with SNF.

Table 5.3

Activity of long-lived radionuclides at the ship propulsion reactors, sunk in the vicinity of Novaya Zemlya as of the end of 1994

5.2.5. Radiation situation in the area of wreck of nuclear submarine Komsomolets

In 1989 in the Sea of Norway, as a result of accident, the nuclear submarine "Komsomolets" sank at a depth of about 1700 m with a ship propulsion nuclear reactor and two rockets with nuclear warheads aboard. Before the accident SPR of NS "Komsomolets" produced about 580 Gwt*hour. To such nuclear fuel burnup there is the following gross activity of both long-lived fission and activation products accumulated in the reactor core: ¹³⁷Cs 3.1x10¹⁵ Bq (83 kCi), ⁹⁰Sr 2.8x10¹⁵ Bq (75 kCi), ²³⁹Pu 4.4x10¹² Bq (118 kCi), ²⁴⁰Pu 1.7x10¹² Bq (46 kCi).

Two nuclear warheads by activity of 1.48x10¹³ Bq (664 kg ²³⁹Pu) are also aboard the NS. Thus, the gross activity of ^239+240Pu comprises 564 Ci (2.1x10¹³ Bq) aboard.

The correlation with other sources of the antropogenic long-lived radionuclides in the North Atlantic (Table 5.4) points to low relative radiation hazard of NS "Komsomolets" for the sea: activity of ¹³⁷Cs, ⁹⁰Sr, ^239+240Pu, the source of which is the NS, is tens times lower than that due to global fallouts and discharges of Western-European radiochemical plants as well as RW sunk earlier.

Table 5.4

Long-lived artificial radionuclides in the north Atlantic

In 1991-1995 the Special Design Bureau of Marine Engineering (SDBME) "Rubin" together with other organizations (The Khlopin Radium Institute, RRC "Kurchatov Institute", etc.) realized a number of marine expeditions aimed at obtaining the objective information about the radiation situation in the region of NS wreck in connection with possible radionuclides release into the sea.

For solving this problem the critical analysis used methods of radionuclide concentrating from large volumes of sea water (including using the selective sorbents), procedures of gamma-spectrometric and radiochemical analysis of the sea water, and samples of bottom sediments and hydrobionts was conducted. The reability of the results obtained has been confirmed taking into account the extreme heterogeneity of the fields of radionuclides of artificial and natural origin in the inspected region.

According to calculations performed it was found that NS and SPR, as a result of the impact of NS against the reactor bottom, lost sealing and radioactive substances gained access to the environment. The rate of the radionuclides release depends on the character of destruction of primary circuit reactor, ship structures, residual heat, state of nuclear warheads and other conditions.

Fission products (¹⁴⁴Ce, ¹³⁷Cs, ⁹⁰Sr, ¹⁰⁶Ru), material activation products of ⁶⁰Co, ⁵⁹Co, ⁵⁴Mn and tritium (3H), as well as plutonium, are the main radionuclides determining the radiation-ecological situation in the area of the NS submersion.

The results of field work, executed in 1991-1995, showed the release of insignificant quantities of a number radionuclides of artificial origin from the damaged NS hull. In the sorbent samples placed directly on the NS hull in addition to ¹³⁷Cs, ¹³⁴Cs is recorded; in the sorbent sample placed in the ventilating trunk - ⁵⁴Mn and ⁶⁰Co. In samples of water, taken by bathometers of deep-sea apparatus "Mir", higher values of tritium concentration as compared with the background levels were found.

In 1994-1995 in the framework of marine expedition on the research ship "Academician Mstislav Keldysh" an extended complex of work on determining the degree of radioactive pollution and radionuclides content of bottom sediments, water and bioobjects was carried in the NS wreck area. The works performed can be divided into two categories:

• executed far from the NS for obtaining the data about background values of the radionuclide concentrations;
• executed near to possible sources of activity release from reactors and nuclear charges onboard the NS.

It has been found from a wealth of serial measurements that the higher concentration of ¹³⁷Cs in the sea water of ~6x10^-10 Ci/l or about 20 Bq/l has been seen only close to outlet hole of ventilation sytem of reactor compartment. According to NRB-76/87 the permissible concentration of ¹³⁷Cs in drinking water is equal to 5.55x10² Bq/l. Thus, the content of this long-lived radionuclide in the sea water is 100 times lower than its permissible concentration in drinking water.

According to the 1991-1994 data the volumetric activity of sea water by ^239,240Pu in the surface layer both in the background points and in the region of the main works was practically identical. The similar picture was also observed for ¹³⁷Cs and for ⁹⁰Sr. In 1991-1994 the bottom-dwelling waters were characterized by approximately identical values of volumetric activity of sea water by ^239,240Pu. The analysis of sea water samples for ⁹⁰Sr and ¹³⁷Cs did not show any results different from the background values.

The performed radiochemical analysis of bottom sediments samples taken during the 1991-1995 field works showed that the variations of the specific activity of ⁹⁰Sr in surface layers of bottom sediments (0 - 2) cm were 0,9 - 2,2 Bq/kg.

The results of determining the specific activity of ^239,240Pu in the surface samples of bottom sediments, taken in close proximity to the NS from the deep-water inhabited apparatus "Mir" show that since 1991 till 1994 the character of plutonium distribution remains practically unchanged. For example, in surface horizons (0 - 1 cm) of bottom sediments investigated the variations of specific activity of plutonium were in 1991 - (0,1 - 1,6) Bq/kg, in 1992 - (0,1 - 1,5)Bq/kg, in 1993 - (0,1 - 1,1) Bq/kg and in 1994 - (0,04 - 1,1) Bq/kg and are within the variations due to "global" fallouts.

Investigating the hydrobionts has shown that samples taken close to or away from NS don’t vary in content of radionuclides in them.

Localization of radionuclide source of reactor origin, as well as measurement of specific activity have made possible the estimation of ¹³⁷Cs release from the reactor compartment into the sea water. It doesn’t exceed 3.7x10¹¹ Bq/year, that is 30 times less than background content of natural radioactive ⁴⁰K in 1 km³ of sea water.

5.3. The characteristic of available data

In the Ministry of Defence are the data on sources and places of producing the radioactive wastes (RW), the technological operations leading to RW formation, the accumulated wastes volumes, their isotope and chemical composition, specific and volumetric activity, reprocessing technology as well as on the environmental contamination, resulting from the Navy activities.

The information, concerning radioactive wastes are not classified. The part of the data, concerning "fresh" and spent nuclear fuel (SNF) is classified. The automated database on the problems of radioactive waste and nuclear material handling is not available. The existing information allows a database to be created, however, at present, it is in an odd state.

Data on the power output of the reactors, radionuclide content in the damaged NS and radiation situation in the compartments are left classified at present.

In three joint reports of the RRC "Kurchatov Institute" and the Navy the detailed primary information on the scale of the accident in the Chazhma Bay and the accompanying radiation situation has been collected. The analysis of this information has allowed the conclusions about providing a means for classifying the main massive of available data without violation of the RF law "On protection of State secret" and in the course of further works on Project 245 to prepare for publishing the monograph "The radiation accident in the Chazhma Bay and its radioecological consequences" of about 7 author's sheets.

The data on character, methods, volumes and activity of RW dumped by the RF Navy for a period from the beginning of 60's to 1992 to the Barents Sea, Kara Sea, Sea of Japan and Sea of Okhotsk has been presented in the report materials of the Governmental commission on the questions connected with marine RW disposal, so called "White Book-93". In the Ministry of Defence there is evidence of regions of marine RW disposal (the radiological and hydrological characteristics of these regions ), as well as summary reports on the radioactive effluents into the sea from the objects of Navy. The data on activity of solid radioactive wastes (SRW) sunk in the sea are inherently approximate, as the calculation of the activity of SRW dumped was made by the simplified procedure and has been expressed in conventional terms of so-called ⁹⁰Sr equivalent. However, the information may be considered reasonable for estimating the radioecological situation and its forecasting.

REFERENCES

5.1. Facts and problems, connected with radioactive wastes dumping in the seas, surrounding the territory of the russian federation, Russian President's administration, Moscow, 1993

5.2. O.I.Petrov, "Radioactive wastes generated by boat nuclear power plants", In Assessment of actual and potentiial consequences of dumping of radioactive wastes into Arctic seas, Vienna, IAEA, 1993, pp.71-74

5.3. Yu.V.Sivintsev, "Monitoring of the Radioactive Contamination near Sunken Submarines". Ibid., 1993, pp.75-80.

5.4. O.I.Petrov, "Environmental and sanitation problems related to radioactive waste dumping into the Arctic Seas", In Environmental Radioactivity in Arctic and Antarctic, Ed. H.Strand and E.Holm. Osteras, 1993, p.97-102.

5.5. Yu.V.Kuznetsov, N.A.Nosov, V.K.Legin, "Dumping of radioactive waste in the sea environment: Scientific and practical aspects", Ibid., 1993, pp. 37-53.

5.6. Yu.V.Kuznetsov, V.K.Legin, "The radioactive contamination of the Northern Seas: approaches to the assessment of the impact on the marine environment. In: Radioactivity and Environmental Security in the Oceans." Woods Hole Oceanographic Institution, Woods Hole, USA, 1993, pp. 379-394.

5.7. G.A.Gladkov, Yu.V.Sivintsev, "The radiation situation in the area of nuclear submarine "Komsomolets" sunk", Atom. Energ., 1994, v.77, N 5, p.379-386

5.8. Radioactive contamination at dumping sites for nuclear waste in the Kara Sea. Results from the Russian-Norwegian 1993 expedition to the Kara Sea. ISBN 82-993079-3-7, November 1994.

5.9. Yu.V.Sivintsev, V.L.Vysotsky, V.A.Danilyan, "Ecological consequences of the radiation accident on the nuclear submarine in the Chazhma Bay", Atom. Energ., 1994, v.76, N 2, pp.158-160

5.10. Report at the scietific practical conference in Severodvinsk, March 15-16, 1995, "Development of plans and specifications for utilizing the operating, damaged and newly built nuclear submarines". SDBME "Rubin"

5.11. O.E.Kiknadze, Yu.V.Sivintsev, "Radioecological danger of long-lived radionuclides in nuclear reactor, dumped in Arctic", In: Environmental Radioactivity in the Arctic, Osteras, 1995, pp.152-155.

5.12. O.E.Kiknadze, Yu.V.Sivintsev, "Radioecological danger of long-lived radionuclides in nuclear reactor, dumped in Arctic", Atom. Energ., 1995, v.79, N 3, pp.204-211

5.13. A.Yu.Kazennov, "Monitoring of sea contamination", I Aleksandrov readings, M.: RRC "Kurchatov Institute", 1995, p.14-25

5.14. V.A.Danilyan, V.L.Vysotsky,. "Safety Issues when Handling Spent Nuclear Fuel and Radioactive Waste in the Pacific Fleet of the Russian Federation". In: "Nuclear Submarine Decommissioning and Related Problems", Ed. by L.L.LeSage and A.A.Sarkisov, NATO ASI Series, Kluwer Academic Publishers, Dordecht, 1996, pp.201 - 208.

5.15. V.A.Danilyan, V.L.Vysotsky, "Radioecological Situation at Bases and Sites for Refueling and Recycling of Nuclear Submarines in the Russian Federation Pacific Fleet" Ibid., 1996, pp.321 - 330.

5.16. A.P.Kuznetsov et al, "Radionuclides in the Benthofauna in the Region of Location of the Nuclear Submarine "Komsomolets", Biology Bull., Vol.23, No.4, 1996, pp.387 - 390.

5.17. Oceanologic researches and submarine technical works at the place of NS "Komsomolets" wreck,. (By edit. M.E.Vinogradov), Moscow: "Nauka", 1996, 362 p.