Kosiewicz, apparently from his letter, a key leader in establishing the design basis for WIPP, says he retired from LANL 11 years ago. It would have served readers well if he had not relied on memory before commenting on our analysis of the barrel incident and our “errors and omissions.”
Among his misstatements:
- He writes, “In our experiments, the major gases produced from radiolysis of cellulosics were carbon dioxide, and carbon monoxide with lesser amounts of hydrogen.” However Fig. 10 of Zerwechk’s 1979 LANL experiment for dry cellulosics shows more hydrogen than any other gas. Fig. 13 on wet cellulosics showed far more hydrogen than any other gas. Fig. 12 containing cellulosics, plastics, and rubbers also showed more hydrogen than other gases.
- He writes, “Large portions of the waste inventory consist of other matrices including plastics, inorganic sludges, cemented wastes, metals, etc.” Alpha radiolysis of plastics produces gases also. Zerwechk’s experiment on polyethylene in his Fig. 11 shows prolific hydrogen. Radiolysis produces gases in all plastics although they are not released rapidly because they do not have the natural growth channels present in every cellulosic material. I expect that sludges contain water in which case there will certainly be hydrogen and oxygen from radiolysis. Although the number of barrels with only metals and cement might be “large”, I expect that they are a small percentage of the 500,000 barrels now in WIPP.
- He writes, “Radiolysis is such a slow process that in our experiments, we had to use much higher levels of plutonium….so we could get enough gas in a few years….”The pressure in Zerwechk’s cylinder containing wet cellulose (corresponding to wet kitty litter) doubled in only 21 days. The experiments he refers to yielded the same rates of explosive gas production as our measurements at Duke on kitty litter. We do not think this gas production rate is slow. We calculate that the D7R7 room where the barrel exploded, now walled off and without ventilation, is building up gases from its other 10,000 barrels at rates that threaten a much larger explosion before WIPP is finally closed.
We had examined the Molecke paper Kosiewicz referred to long before our Santa Fe presentation. It addresses the distant time (1,000 years?) when the salt has totally enveloped the barrels, the barrels are being corroded by the small amount of water in the salt, the cellulosic material is rotting, and radiolytic gas production is assumed to have died away except for gas production from alpha radiolysis of the small amount of water in the salt that has accessed the barrel interior. We generally concur with Molecki’s description of what ADNA Corporation calls this “forever” period.
But getting to “forever” is the problem. Zerwechk’s measurements showed that the gas production rate will decrease from its maximum by a factor of about two in about 200 years. Zerwechk shows that during this time, the pressure in any WIPP barrel loaded with the maximum permitted plutonium in wet kitty litter would increase its pressure by 14.7 psi about 100 times to about 1,470 psi. Zerwechk’s high pressure gases would be confined to the barrel or its immediate surroundings by the hermetically sealing salt. If a barrel such as this were accidentally drilled into with grinding causing the gas to explode, the gas pressure would rise to about 10,000 psi (at about 2000 C) compared to the pressure from the salt overburden of about 2,000 psi. The explosion would spread to neighboring barrels and perhaps throughout WIPP. We will not try to predict the consequences.
In any case, this level of gas production in the “near” period is far more than WIPP was designed to accommodate. DOE-EM has already acknowledged the seriousness of the alpha-particle-induced poisonous gas generation impeding the Hanford tank waste cleanup and is seeking a solution. DOE-EM should acknowledge the much more serious consequences of an unanticipated explosion from alpha-particle-induced gases in WIPP and seek a solution there also. Fortunately mitigation methods are probably available to save WIPP for its intended purpose.