Apparatus and method for chemically decontaminating a PWR reactor coolant system

United States Patent m

Stenger

[54] APPARATUS AND METHOD FOR

CHEMICALLY DECONTAMIN ATING A
PWR REACTOR COOLANT SYSTEM

[75] Inventor: William J. Stenger, Penn Township, Westmoreland County, Pa.

[73] Assignee: Westinghouse Electric Corp., Pittsburgh, Pa.

[21] Appl. No.: 999,343

[22] Filed: Dec. 31,1992

[51] Int. C1.5 G21C 9/00

[52] UJS. CI 376/305; 376/310;

376/313

[58] Field of Search 376/305, 306, 310, 313

[56] References Cited

U.S. PATENT DOCUMENTS

3,783,268 1/1974 Neeb et al 250/83.3 R

4,684,494 8/1987 Dagard 376/313

4,699,755 10/1987 Dagard et al 376/313

4,842,812 6/1989 Panson et al 376/306

5,082,618 1/1992 Dagard 376/219

Primary Examiner—Donald P. Walsh

US005377244A

[ii] Patent Number: 5,377,244 [45] Date of Patent: Dec. 27,1994

Assistant Examiner—Frederick H. Voss

[57] ABSTRACT

The reactor coolant system (RCS) of a pressurized water reactor (PWR) is chemically decontaminated and cleaned utilizing apparatus which is comprised of components designed to operate at low pressures while still utilizing installed reactor coolant pumps and/or the residual heat removal pumps to generate the high flow rates required for the process. A high volume diverted flow of reactor coolant from the RCS is passed through letdown valves to reduce the high pressure produced by the installed pumps. Chemical decontamination and cleaning agents are mixed with the low pressure diverted flow and returned to the RCS by high head injection pumps. Contamination solubilized by the decontamination and cleaning agents is removed as the reactor coolant is recirculated through demineralizers. Filters remove particulates, and fines from the demineralizer resins. A surge tank, which may or preferably is not, in the path of the diverted flow provides reactor coolant for backwashing the demineralizers and filters and downloading the demineralizer resins.

14 Claims, 3 Drawing Sheets