**\[DNFSB LETTERHEAD\]**

June 18, 2004

The Honorable Kyle E. McSlarrow

Deputy Secretary of Energy

1000 Independence Avenue, SW

Washington, DC 20585-1000

Dear Mr. McSlarrow:

In response to a letter from the Defense Nuclear Facilities Safety Board
(Board) dated March 24, 2004, the Department of Energy (DOE) briefed the
Board on April 27, 2004, regarding its plans for management and
disposition of radioactive wastes at the Savannah River Site (SRS). The
program plan outlined during the briefing is sound and incorporates many
of the principles and insights imparted to DOE by the Board during the
last several years, including early demonstration of decontamination
technologies, minimal reliance on the unproven Low Curie Salt initiative
and elimination of recycle waste from the Defense Waste Processing
Facility with an acid-side evaporator. If executed, this plan offers a
high probability of successfully alleviating shortages of compliant tank
space that both threaten vital site risk-reduction activities and lead
to operational strategies involving increased safety risks.

Unfortunately, DOE suspended execution of this plan in early 2004 and
withheld associated funding. On June 7, 2004, in light of certain
legislative developments and the serious consequences of additional
delays, DOE re-authorized this funding.

The Board believes that the safety impacts of delaying the radioactive
waste disposition activities at SRS, as discussed in the enclosed
report, are unacceptable. Given the significant safety consequences of
delaying radioactive waste disposition at SRS, it is imperative that DOE
execute this program in a timely manner.

Sincerely,

***John T. Conway***

***Chairman***

c: The Honorable Jessie Hill Roberson

Mr. Mark B. Whitaker, Jr.

Enclosure

**DEFENSE NUCLEAR FACILITIES SAFETY BOARD**

**Staff Issue Report**

May 19, 2004

**MEMORANDUM FOR:** J. K. Fortenberry, Technical Director

**COPIES:** Board Members

**FROM:** T. D. Bums

> J. S. Contardi

**SUBJECT:** Safety Impacts of Suspending Salt Disposition at the
Savannah River Site

The status of compliant tank space in the high-level waste (HLW) tank
farms at the Savannah River Site (SRS) is currently worse than when the
Defense Nuclear Facilities Safety Board (Board) issued Recommendation
2001-1, *High-Level Waste Management at the Savannah River Site*, in
March 2001. Although it was recognized that working space in compliant
tanks would continue to decrease until salt removal capabilities had
been developed and implemented, the salt disposition program was
expected to proceed in a manner that would enable space gains through
salt removal before compliant working space had decreased to the point
of hindering vital site risk-reduction activities, such as sludge
vitrification and stabilization of nuclear materials.

Recent programmatic decisions by the Department of Energy (DOE) to
suspend the development of salt decontamination capabilities at SRS have
called into question the ability of the salt disposition program to
provide the compliant tank space necessary to execute accelerated
cleanup plans for site-wide risk reduction and avoid a significant
increase in the risks associated with operational activities at the tank
farms. To avoid significant safety risks and major increases in the
life-cycle cost of waste cleanup at SRS, the salt disposition program as
currently envisioned and briefed to the Board by DOE on April 27, 2004,
needs to be executed without interruption.

**Background.** SRS has 51 HLW tanks that store approximately 36 million
gallons of waste generated from the production of defense nuclear
materials. The tanks are located in two separate locations, known as the
H-Area Tank Farm and the F-Area Tank Farm. There are four different
types of tanks---Types I through IV. Only Type III tanks meet modern
requirements for secondary containment as stipulated by the
Environmental Protection Agency for leak protection. The Type I tanks
are the oldest and were constructed between 1952 and 1953. The Type III
tanks are the newest and entered service between 1969 and 1986. Many of
the HLW tanks are already well beyond their nominal 30-year design life.

*Waste Characteristics*---The waste stored in the tanks includes
insoluble metal hydroxide sludges and soluble salt supernate.
Evaporators are used to reduce the volume of the supernate. If
concentrated enough, the soluble salts in the supernate will reach their
solubility limit and precipitate out of the supernate. The precipitated
salts are commonly referred to as salt cake.

The sludge component of the HLW represents approximately 3 million
gallons of the total 36 million gallons stored in the tanks. However,
the vast majority of the long-lived (half-life \>1,000 years)
radionuclides (i.e., actinides) are contained in the sludge. The sludge
is currently being stabilized in the Defense Waste Processing Facility
(DWPF) through vitrification for disposal in a deep geologic repository.

The major radioactive constituent in salt waste is the relatively
short-lived (30-year half-life) cesium-137 nuclide, although lower
levels of actinide contamination are present.

Depending on the particular waste stream (e.g., canyon wastes, basin
effluents), the concentration of cesium may vary. The precipitation of
salts following evaporation can also change the cesium concentration.
The concentration of cesium is much lower than that of the
nonradioactive salts in the wastes, such as sodium nitrate and nitrite;
therefore, the cesium does not reach its solubility limit and will not
precipitate. As a result, the concentration of cesium in the salt cake
is much lower than that in the supernate.

*Historical Waste Management Operations and Planning*---The failure of
the In-Tank Precipitation (ITP) process for salt waste decontamination
in 1998 resulted in an inability to remove and dispose of salt waste
from the SRS tank farms, which in turn led to serious shortages of space
in compliant Type III waste tanks. Subsequent reliability issues with
the three HLW evaporators exacerbated the tank space problems to such a
degree that imprudent operational strategies were considered, and in
some cases implemented, to maintain the ability of the tank farms to
support site activities related to vitrification and nuclear material
processing. An example of these questionable operational strategies is
the transfer of waste into noncompliant Type I single-shell tanks. The
first tanks used in this manner, Tanks 5 and 6, leaked almost
immediately.

Given the clear safety risks associated with the operational strategies
implemented at SRS to deal with insufficient compliant tank space, the
Board issued Recommendation 2001-1 in March 2001. In Recommendation
2001-1, the Board pointed out the reduction in safety margins arising
from short-sighted operational strategies at SRS and recommended that
DOE vigorously accelerate the only true solution to the tank space
problem-a salt waste decontamination and disposal capability to replace
the failed ITP process. DOE accepted Recommendation 2001-1 and provided
an implementation plan committing to the expedited development and
implementation of a salt waste decontamination and disposal capability.
When DOE announced its accelerated cleanup program for reducing risks
associated with legacy nuclear materials, facilities, and wastes in
2002, it was recognized that timely development and implementation of a
salt waste decontamination and disposal capability was key to the
program's success.

As part of its strategy, DOE planned to capitalize on the expected low
concentration of cesium in the salt cake. Based on limited data, DOE
decided to pursue a Low Curie Salt (LCS) initiative, in which salt cake
would be drained of supernate, dissolved, processed in an existing
facility to remove actinides (if needed), then disposed on site in
near-surface saltstone monoliths. The LCS initiative was optimistically
expected to dispose of two-thirds of all salt waste. The concentrated
supernate and other salt waste containing high cesium and actinide
concentrations would be processed for decontamination through a new Salt
Waste Processing Facility (SWPF) prior to on-site disposal. SWPF would
incorporate a new caustic-side solvent extraction technology for cesium
removal and produce a decontaminated low-level waste stream that would
meet Class A requirements. The cesium and actinides extracted at SWPF
would be sent to DWPF for vitrification.

*Revised Salt Processing Program Plan*---The viability of the LCS
initiative was called into question when initial salt cake
characterization samples indicated that cesium and actinide
concentrations exceeded the levels previously assumed. In response to
this technical difficulty, the DOE's Savannah River Operations Office
developed a revised salt waste disposition strategy that minimized
reliance on the LCS initiative while still meeting the risk-reduction
goals of the accelerated cleanup program. The revised strategy calls for
the majority of the salt waste to be processed for decontamination
through either SWPF or a new near-term SWPF pilot facility. To handle
the increased processing requirements, the throughput capacity of SWPF
was increased nearly twofold through process optimization and prudent
technology selection. An acid-side evaporator was also chosen for
implementation at DWPF to preserve working space in compliant Type III
tanks by minimizing the volume of recycle waste returning to the tank
farms.

The revised salt waste disposition strategy is sound and incorporates
many of the principles and insights that the Board has imparted to DOE
during the last several years,

including early demonstration of decontamination technologies, minimal
reliance on the unproven LCS initiative, and elimination of DWPF recycle
waste with an acid-side evaporator. If executed, this revised strategy
offers a high probability of successfully alleviating shortages of
compliant tank space that both threaten vital risk-reduction activities
at the site and lead to operational strategies involving increased
safety risks. Unfortunately, DOE suspended execution of this plan in
early 2004 and withheld associated funding.

**Safety Impacts of Suspending Salt Disposition Activities.** If not
addressed, the shortage of compliant Type III tank space will increase
the risks inherent in HLW processing and management. As the available
tank space dwindles, it will become necessary to decide whether to
continue important activities associated with sludge vitrification and
stabilization of nuclear materials at the cost of employing undesirable
operational strategies in the tank farms, or suspend these vital
risk-reduction activities altogether. These decisions will be very
difficult since delays in these risk-reduction activities could result
in extended storage of liquid radioactive materials in facilities well
beyond their design life, with safety controls that in many cases are
less than ideal and rely heavily on compensatory measures. Some of the
proposed operational strategies are similar to those that led the Board
to issue Recommendation 2001-1 in March 2001. Outlined below are a few
examples of undesirable operational strategies that either have been
implemented or are being considered, along with the associated safety
implications.

*Increased Complexity of Waste Transfer*---The storage of tank farm
space forces more frequent and complex waste transfers. The increase in
waste transfers can be readily observed from historical transfer data.
Between 1987 and 1996, there were no inter-area transfers between the F
and H tank farms; by contrast, the shortage of available space mean that
more than nine such transfers are expected in 2005 alone. Moreover, the
total volume of waste transferred in a year now far exceeds the entire
waste volume stored in the tank farms. This increase in the number of
transfers and the total volume transferred are the result of the lack of
available tank space. For large transfers to take place, a space equal
to the transfer volume must be cleared. Sometimes this requires sending
waste from one tank to multiple receiving tanks. As an example, the
waste in Tank 49 was removed to provide a feed tank for the LCS program.
Thirteen individual transfers totaling more than 3 million gallons of
waste were required to remove the waste from this one tank. The
increased transfer volumes and rates increase the probability of
transfer errors and leaks in facilities already beyond their expected
design life.

*Reduction in Contingency Tank Space*---Previously, 1.3 million gallons
of compliant Type III tank space was kept free in both F and H tank
farms (total of 2.6 million gallons of space) to provide contingency
space in the event of a leaking tank. Keeping space free in both tank
farms reflected the difficulty associated with transferring waste
between the F and H tank farms in a timely manner. Recently, the
decision was made to reduce the contingency tank space requirement by
one-half such that a total of only 1.3 million gallons of space would be
held free. The allotted space is not within a single tank, but is spread
among multiple tanks in both tank farms. If a tank containing a large
volume of waste were to leak, the reduction in contingency space could
significantly hamper emergency response operations by greatly increasing
the number and complexity of the transfers needed to empty the leaking
tank.

*Expanded Use of Noncompliant Tanks without Secondary
Containment*---Eight of the 51 HLW tanks at SRS are Type IV tanks. These
tanks were constructed during 1958-1962, have a single steel wall, and
are beyond their design life. Two of the tanks have known cracks that
may have been caused by corrosion due to groundwater. Two of the tanks
have been operationally closed by being filled with grout. To create
more space in the compliant Type I11 tanks, short-term storage of
concentrated salt waste may be initiated in Type IV tanks. The
concentrated salt waste contains radionuclide concentrations more than
an order of magnitude greater than those of the DWPF recycle waste
currently stored in the Type IV tanks. A previous attempt to expand the
use of old-style tanks resulted in leakage and precipitated the issuance
of the Board's Recommendation 2001-1.

*Use of 3H Evaporator for D WPF Recycle Waste*---As a result of
vitrification operations, DWPF annually produces approximately 1.45
million gallons of recycle waste that is transferred to the tank farms.
This recycle waste is segregated from canyon waste and concentrated in
separate evaporators for criticality safety reasons. Specifically, when
recycle waste, with high silica content, and canyon waste, with high
aluminum content, are mixed and evaporated, deposits that contain
significant concentrations of uranium form in the evaporator. Removal of
the deposits can result in accumulation of solutions with elevated
uranium concentrations in unfavorable geometries. Currently, the 2H
evaporator system is used exclusively for recycle waste, and 3H is used
exclusively for canyon wastes. A nonsegregated evaporator usage regime
would allow more waste to be processed through the higher-capacity 3H
evaporator and would serve to increase the tank space recovered by waste
concentration. However, the enrichment of the uranium in the 3H system
is higher than that of the uranium in the 2H system, further
exacerbating the criticality risks associated with the formation of
deposits. Despite the increased criticality risks, this compensatory
measure will likely be pursued if the development of salt
decontamination and disposal capabilities is suspended.

*Redefinition of Tank 49 and 50 Process Missions*---Tank 49 was
previously used for storage of filtrate from the canceled ITP process.
The organic waste in Tank 49 has been treated and the waste
dispositioned. Tank 49 was to have been used as the feed tank for salt
decontamination activities. However, Tank 49 may now be used to support
sludge preparation to prevent near-term disruptions of DWPF operations.
Tank 50 is the feed tank for the Saltstone Production Facility (SPF).
Since SPF stabilizes only low-level waste, Tank 50 has not been used for
storage of HLW. As with Tank 49, Tank 50 may be used to support sludge
preparation to prevent near-term disruptions of DWPF operations.
Redefining the storage missions for Tanks 49 and 50 may alleviate some
near-term tank space issues but will significantly impair future salt
disposition activities. SRS estimates that this strategy would delay
overall cleanup of the HLW by at least 3 years and increase life-cycle
costs by an estimated \$1.5 billion.

**Summary and Conclusions.** The safety implications of exacerbating the
shortage of compliant tank space at SRS by failing to proceed with the
development of salt waste removal and decontamination capabilities are
significant. Vital risk-reduction activities at the site, such as sludge
vitrification and stabilization of nuclear materials, would be delayed,
extending the time during which liquid radioactive waste will be stored
in facilities well beyond their design life, with safety controls that
in many cases are less than ideal and rely heavily on compensatory
measures. Additionally, more aggressive operational strategies with
increased safety risks would be required to manage an increasingly full
HLW system.

A revised salt waste disposition strategy has been developed for SRS
that addresses many of the Board's previously identified issues and
incorporates many of the Board's previous insights. The revised strategy
is robust and, if executed, has a high probability of successfully
alleviating compliant tank space shortages that both threaten vital site
risk-reduction activities and lead to operational strategies with
increased safety risks. This revised salt disposition strategy should be
executed without delay.