Patent Number: 
Section: claims

1. A water jet peening apparatus, comprising:a nozzle arranged in water and includes a mouth from which water is jetted out;a detecting device arranged in the water and detects sound in at least a part of a period during which the water is being jetted out from the mouth;a processing device determining presence or absence of abnormality in the nozzle based on a result of the detection by the detecting device; anda first covering member disposed on at least a part of region between the detecting device and the nozzle, whereinthe processing device compares the sound detected by the detecting device to a reference sound obtained beforehand by using the nozzle in a normal state, and determines presence or absence of the abnormality in the nozzle based on a change in a sound pressure level at a predetermined frequency. 2. The water jet peening apparatus according to claim 1, wherein the processing device determines a type of the abnormality based on a frequency of the sound that has changed in sound pressure level thereof. 3. The water jet peening apparatus according to claim 1, wherein the abnormality of the nozzle includes wearing of the nozzle. 4. The water jet peening apparatus according to claim 1, whereinan internal space between the first covering member and the detecting device is filled with water. 5. The water jet peening apparatus according to claim 4, wherein the first covering member includes a hole which opens an internal surface of the first covering member and an external surface of the first covering member, and connects the internal space with an external space of the first covering member. 6. The water jet peening apparatus according to claim 5, further comprising:a lid member arranged in the hole. 7. The water jet peeing apparatus according to claim 4, further comprising:a second covering member that is arranged to cover the external surface and the internal surface of the first covering member and made of rubber. 8. The water jet peening apparatus according to claim 1, whereinthe nozzle and the detecting device are arranged in the water inside a nuclear reactor vessel,the nozzle jets out the water from the mouth at a deepest portion of the nuclear reactor vessel, andthe detecting device detects sound from an arbitrary water depth including the deepest portion of the nuclear reactor vessel. 9. The water jet peeing apparatus according to claim 1, wherein the first covering member has a spherical shape. 10. The water jet peeing apparatus according to claim 1, whereinthe processing device determines presence or absence of the abnormality in the nozzle based on a change in the sound pressure level within a predetermined frequency range. 11. A water jet peening method, comprising:providing a covering member on at least a part of region between a detecting device and a nozzle;jetting out water from a mouth of the nozzle in a state where the mouth and a target to be processed that are arranged in water are opposite to each other;detecting sound by a detecting device arranged in the water in at least a part of a period during which the water is being jetted out from the mouth; anddetermining presence or absence of abnormality in the nozzle based on a result of the detection by the detecting device, whereinthe determining step compares the sound detected in the detecting step to a reference sound obtained beforehand by using the nozzle in a normal state, and determines the presence of absence of an abnormality in the nozzle based on a change in a sound pressure level at a predetermined frequency. 12. The water jet peening method according to claim 11, wherein a type of the abnormality is determined based on a frequency of the sound that has changed in sound pressure level thereof. 13. The water jet peening method according to claim 11, wherein the abnormality in the nozzle includes wearing of the nozzle. 14. The water jet peening method according to claim 11, whereinthe nozzle and the detecting device are arranged in the water inside a nuclear reactor vessel,the target to be processed includes the nuclear reactor vessel,the nozzle jets out the water from the mouth at a deepest portion of the nuclear reactor vessel, andthe detecting device detects sound from an arbitrary water depth including the deepest portion of the nuclear reactor vessel. 15. The water jet peening method according to claim 11, wherein the providing step includes,providing the covering member having a spherical shape. 16. The water jet peening method according to claim 11, further comprising:filling an internal space between the covering member and the detecting device with water. 17. The water jet peening method according to claim 11, whereinthe determining step determines the presence of absence of an abnormality in the nozzle based on a change in the sound pressure level within a predetermined frequency range. 18. A method of evaluating a nozzle of a water jet peening apparatus having a mouth from which water is able to be jetted out, the method comprising:providing a covering member on at least a part of region between a detecting device and the nozzle;jetting out water from the mouth of the nozzle in a state where the nozzle is arranged in water;detecting sound by a detecting device arranged in the water in at least a part of a period during which the water is being jetted out from the mouth; anddetermining presence or absence of abnormality in the nozzle based on a result of the detection by the detecting device, whereinthe determining step compares the sound detected in the detecting step to a reference sound obtained beforehand by using the nozzle in a normal state, and determines the presence or absence of the abnormality in the nozzle based on a change in a sound pressure level at a predetermined frequency. 19. The method of evaluating a nozzle according to claim 18, wherein a type of the abnormality is determined based on a frequency of the sound that has changed in sound pressure level thereof. 20. The method of evaluating a nozzle according to claim 18, wherein the abnormality of the nozzle includes wearing of the nozzle. 21. The method of evaluating a nozzle according to claim 18, wherein the providing step includes,providing the covering member having a spherical shape. 22. The water jet peening method according to claim 18, further comprising:filling an internal space between the covering member and the detecting device with water. 23. The water jet peening method according to claim 18, whereinthe determining step determines the presence of absence of an abnormality in the nozzle based on a change in the sound pressure level within a predetermined frequency range.