Method and apparatus for controlling a nuclear reactor

A method for preventing the violation of a Nuclear Steam Supply System design limit said system having a nuclear reactor with a core and having fuel pins and channels therein through which a coolant is circulated, said method comprising the steps of;

• a. continuously generating a multiplicity of electrical parametric signals which are commensurate with a multiplicity of Nuclear Steam Supply System parameters, said parameters including the parameters used in calculating the DNBR of said reactor core;
• b. periodically sampling said parametric signals;
• c. generating from said periodic samples of said parametric signals a periodic DNBR electrical signal commensurate with the DNBR of said reactor core at the time of said sampling;
• d. continuously comparing one of said continuously generated parametric signals to the periodically sampled signal of the same parameter used to generate the next previous periodic DNBR signal;
• e. generating an electrical signal commensurate with the change in DNBR due to the change in said parameter;
• f. continuously generating an updated DNBR signal responsive to the electrical signal commensurate with the periodic DNBR of said reactor core at the time of said sampling and said electrical signal commensurate with the net change in DNBR due to the change in said parameter to continuously generate an electrical signal commensurate with the actual DNBR of said reactor core;
• and
• g. correctively regulating said Nuclear System when the continuously generated DNBR signal indicates a design limit violation.

An improved Nuclear Power System Protection Apparatus for the prevention of the violation of a nuclear power system design limit the proximity to which is indicated by an index, the improvement comprising:

• a. means for determining a time derivative of said index or a component part thereof;
• b. means responsive to said time derivative for multiplying said time derivative by a positive time period (T) to generate an electrical signal commensurate with a projection of said index into the future over said time period (T);
• and
• c. means responsive to said electrical signal commensurate with a projection of said index for correctively regulating said nuclear power system.

An improved method for the protection against violation of a nuclear power system design limit the proximity to which is indicated by an index, the improvement comprising:

• a. determining a time derivative of said index or a component part thereof;
• b. multiplying said time derivative by a positive time period (T) to generate an electrical signal commensurate with a projection of said index into the future over said time period (T);
• and
• c. correctively regulating said nuclear power system in response to said electrical signal commensurate with a projection of said index.

A method for preventing the violation of a nuclear steam supply system design limit said system having a nuclear reactor with a core and having fuel pins and channels therein through which a coolant is circulated, said method comprising the steps of:

• a. generating a multiplicity of electrical parametric signals which are commensurate with a multiplicity of nuclear steam supply system parameters, said parameters including the parameters used in calculating the DNBR of said reactor core;
• b. generating from said parametric signals of step (a) an electrical signal commensurate with a projection of DNBR over a predetermined time period (T), said projection generating step including the steps of determining from said parametric signals a time derivative and multiplying said time derivative by a positive value of said time period (T);
• c. generating an electrical set point signal commensurate with the minimum allowable DNBR value;
• d. comparing said signal commensurate with said projection of DNBR and said signal commensurate with the minimum allowable DNBR value;
• and
• e. correctively regulating said reactor when said signal commensurate with said projected DNBR equals or falls below said signal commensurate with the minimum allowable DNBR value.

An improved Nuclear Power System fuel damage projection apparatus for the prevention of the violation of a fuel design limit, said apparatus being of the type which utilizes an index which is representative of the proximity of the violation of said design limit, said index being mathematically represented by an equation which defines the functional relationship between said index and a multiplicity of system parameters, said apparatus including means for continuously generating a multiplicity of electrical signals which each vary as a function of one of said multiplicity of system parameters and means responsive to said multiplicity of said electrical signals for generating an electrical signal commensurate with said index, the improvement comprising:

• a. means responsive to one of said continuously generated electrical parametric signals for generating an electrical signal commensurate with a projection of said index due to the projected change of said one electrical parametric signal over a projected time period (T), said means for generating an electrical signal commensurate with a projection of said index including means responsive to the rate of change of said one parametric signal for generating a signal commensurate with a projected change of index due to the projected change of said one parametric signal over a projected time period (T);
• and
• b. means for summing said signal commensurate with a projected change of index and said electrical signal commensurate with said index for generating an electrical signal commensurate with a projected index due to the change of said one parametric signal over a projected timer period (T).
• c. means responsive to said electrical signal commensurate with a projection of said index for correctively regulating said Nuclear Power System.

An improved Nuclear Power System fuel damage protection apparatus for the prevention of the violation of a fuel design limit, said apparatus being of the type which utilizes an index which is representative of the proximity of the violation of said design limit, said index being mathematically represented by an equation which defines the functional relationship between said index and a multiplicity of system parameters, said apparatus including means for continuously generating a multiplicity of electrical signals which each vary as the function of one of said multiplicity of system parameters and means responsive to said multiplicity of electrical signals for generating an electrical signal commensurate with said index, wherein said index is Departure From Nucleate Boiling Ratio (DNBR) and wherein said apparatus includes means responsive to one of said continuously generated electrical parametric signals for generating an electrical signal commensurate with a projection of said index due to the project change of said one electrical parametric signal over a projected time period (T), and wherein the improvement comprises:

• 1. means responsive to one of said parametric signals commensurate with a Nuclear Power System parameter for generating an electrical signal commensurate with a change in DNBR due to the change of said one parameter with respect to the long term average value of said parameter, said average value constrained to be equal to or less limiting on DNBR than the continously generated value of said parameter;
• 2. means for generating an electrical signal commensurate with a preselected value of DNBR which is higher by a predetermined margin than the minimum allowable value of DNBR for which a critical heat flux is exceeded;
• 3. means responsive to said signals of elements (1) and (2) for summing said signals to generate a signal commensurate with an updated DNBR margin;
• 4. means responsive to said updated DNBR margin signal of element (3) and to said electrical signal commensurate with said index (DNBR index) for selecting the larger of the two signals;
• 5. means responsive to said one parametric signal for generating an electrical signal commensurate with a projected change of said parameteric signal over a projected time period (T), said projected change being limited to negative values;
• 6. means responsive to said larger signal of element (4) and to said signal commensurate with a projected change of DNBR due to the projected change of said parametric signal over a projected time period (T) of element (5) for summing said signals of elements (5) and (4) to produce a signal commensurate with the projected value of the DNBR;
• and
• 7. means responsive to said electrical signal commensurate with the projected value of DNBR for correctively regulating said Nuclear Power System when the projected value of the DNBR violates a design limit.